Prof. Dr. Javier Campos

Publications

Books and Collections:

All references:
BibTeX file. PDF file. Google Scholar profile. My Co-Authors/Co-Editors.

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R. J. Rodríguez and J. Campos, “On Throughput Approximation of Resource-Allocation Systems by Bottleneck Regrowing,” IEEE Transactions on Control Systems Technology, vol. 27, iss. 1, pp. 370-377, 2019.
[Bibtex]

@ARTICLE{RC-TCST-19,
author = {R.J. Rodr\'{i}guez and J. Campos},
title = {On Throughput Approximation of Resource-Allocation Systems by Bottleneck Regrowing},
journal = {IEEE Transactions on Control Systems Technology},
year = {2019},
volume = {27},
pages = {370-377},
number = {1},
month = {January},
abstract = {Complex systems, such as manufacturing, logistics, or Web services, are commonly modeled as discrete event systems dealing with the resource-allocation problem. In particular, Petri nets (PNs) are a widely used formalism to model these systems. Although their functional properties have been extensively studied in the literature, their nonfunctional properties (such as throughput) have usually been ignored. In this brief, we focus on a PN subclass useful for modeling concurrent sequential processes with shared resources, termed S4PR nets. For these nets, we present an iterative strategy that makes intensive use of mathematical programming problems to approximate system throughput. Initially, our strategy selects the slowest part (a subsystem) of the net. Then, the next slowest parts are considered. In each step, the throughput is computed solving analytically the underlying continuous-time Markov chain when feasible (or by simulation, otherwise). Since only certain subsystems are considered, the state-explosion problem inherent to the increasing net size is mitigated. We evaluate our strategy in a set of randomly generated S4PR nets. Our findings show that the throughput improves the upper throughput bound computation by almost 20% and that small portions of the net are enough to approximate system throughput.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/rc-tcst-19.pdf},
doi={10.1109/TCST.2017.2768512}
}

R. J. Rodríguez and J. Campos, “Extended Abstract: On Throughput Approximation of Resource-Allocation Systems by Bottleneck Regrowing,” in Actas de las XXV Jornadas de Concurrencia y Sistemas Distribuidos, Toledo, Spain, 2018.
[Bibtex]

@INPROCEEDINGS{RC-JCSD18,
author = {R.J. Rodr\'{i}guez and J. Campos},
title = {Extended Abstract: On Throughput Approximation of Resource-Allocation Systems by Bottleneck Regrowing},
booktitle = {Actas de las {XXV} Jornadas de Concurrencia y Sistemas Distribuidos},
year = {2018},
address = {Toledo, Spain},
month = {June},
publisher = {Universidad Complutense de Madrid y Universidad de Castilla-La Mancha},
abstract = {Complex systems, such as manufacturing, logistics, or Web services, are commonly modeled as discrete event systems dealing with the resource-allocation problem. In particular, Petri nets (PNs) are a widely used formalism to model these systems. Although their functional properties have been extensively studied in the literature, their nonfunctional properties (such as throughput) have usually been ignored. In this brief, we focus on a PN subclass useful for modeling concurrent sequential processes with shared resources, termed S4PR nets. For these nets, we present an iterative strategy that makes intensive use of mathematical programming problems to approximate system throughput. Initially, our strategy selects the slowest part (a subsystem) of the net. Then, the next slowest parts are considered. In each step, the throughput is computed solving analytically the underlying continuous-time Markov chain when feasible (or by simulation, otherwise). Since only certain subsystems are considered, the state-explosion problem inherent to the increasing net size is mitigated. We evaluate our strategy in a set of randomly generated S4PR nets. Our findings show that the throughput improves the upper throughput bound computation by almost 20% and that small portions of the net are enough to approximate system throughput.},
note = {See the paper \cite{RC-TCST-19}},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/rc-jcsd18.pdf},
doi={}
}

S. Pérez, J. Campos, H. Facchini, and A. Dantiacq, “Experimental Study of Unicast and Multicast Video Traffic using WAN Test Bed,” in Proceedings of the 2016 IEEE Biennial Congress of Argentina (ARGENCON’16), Buenos Aires, Argentina, 2016, pp. 1-6.
[Bibtex]

@INPROCEEDINGS{PCFD-ARGENCON-16,
author = {S. P{\'e}rez and J. Campos and H. Facchini and A. Dantiacq},
title = {Experimental Study of Unicast and Multicast Video Traffic using {WAN} Test Bed},
booktitle = {Proceedings of the 2016 IEEE Biennial Congress of Argentina {(ARGENCON'16)}},
year = {2016},
pages = {1-6},
address = {Buenos Aires, Argentina},
month = {June},
publisher = {IEEE Computer Society},
abstract = {The deployment of IP multicast protocols in each
router in the path is needed to access the benefits of the
multicast. IP multicast exists today mainly in LAN networks
and in small areas of highly controlled interconnected
networks. In fact, some companies started to offer tailored
solutions to try to overcome these limitations. On the other
hand, over the last decade, the multimedia applications have
expanded rapidly, and in particular in video applications.
There are Internet sites that offer movies on-line; and it is
common for users to upload and download videos with sites
like YouTube (\copyright Google Inc.). The video call via the Internet is
common with applications, such as Skype (\copyright Microsoft). The
growth of video traffic should be taken into account when
designing a network. Understanding the behavior of the video
traffic and the requirements for the network helps network
administrators to improve the traffic planning. In this work, a
quantitative analysis is performed by experimentation, in
order to evaluate the behavior and impact of video traffic on
WAN networks. We propose a WAN test bed composed by a
video traffic server and several client stations that allows
injecting unicast and multicast video traffic, compressed with
several codecs. From capturing video traffic, we identified
several interesting unicast and multicast performance metrics,
such as: throughput, number of frames, delays, jitter, and
interframe spaces and frame sizes distributions. Several
factors have been taken into account: the video resolution
configuration, the type of video, and restrictions on the
bandwidth, as in a corporate real WAN link of some few
Mbps. This study facilitates the comparison of the results with
those obtained from analytical and modelling studies for
different contexts.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pcfd-argencon-16.pdf},
doi={10.1109/ARGENCON.2016.7585260}
}

S. Pérez, H. Facchini, J. Campos, C. Taffernaberry, F. Hidalgo, and S. Méndez, “Behavior of Codecs for Multicast Video Traffic using WAN Test Bed,” in Proceedings of the 2015 Chilean Conference on Electrical, Electronics Engineering, Information and Communication Technologies (CHILECON’15), Santiago, Chile, 2015, pp. 269-274.
[Bibtex]

@INPROCEEDINGS{PFCTHM-CHILECON-15,
author = {S. P{\'e}rez and H. Facchini and J. Campos and C. Taffernaberry and F. Hidalgo and S. M{\'e}ndez},
title = {Behavior of Codecs for Multicast Video Traffic using {WAN} Test Bed},
booktitle = {Proceedings of the 2015 Chilean Conference on Electrical, Electronics Engineering, Information and Communication Technologies {(CHILECON'15)}},
year = {2015},
pages = {269-274},
address = {Santiago, Chile},
month = {October},
publisher = {IEEE Computer Society},
abstract = {In recent years there has been an exponential
increase in the growth in multimedia applications, and in
particular in video applications. Understanding the behavior of
the video traffic and the requirements for the network helps
network administrators to improve the traffic. In this work, a
quantitative analysis is performed by experimentation, in order
to evaluate the behavior and impact of video traffic on WAN
networks. We propose a WAN test bed composed by a video
traffic server and several client stations. This article introduces a
scenario that allows to inject multicast video traffic, compressed
with several codecs. From capturing video traffic, we identified
several interesting performance metrics, such as multicast
throughput, interframe space and frame size distributions, and
the number of frames. We include detailed contributions on the
impact produced by several factors, such as the configuration of
the resolution of the video, the video class, the codec used for the
compression, and the use of multicast traffic when there are
restrictions on the bandwidth, as in a corporate real WAN link of
some few Mbps. This study facilitates the comparison of the
results with those obtained from analytical studies and modelling
for different contexts.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pfcthm-chilecon-15.pdf},
doi={10.1109/Chilecon.2015.7400387}
}

Quantitative Evaluation of Systems, J. Campos and B. Haverkort, Eds., Springer, 2015, vol. 9259. [Publisher URL]
[Bibtex]

@Book{QEST2015,
Title = {Quantitative Evaluation of Systems},
Year = {2015},
Editor = {J. Campos and B. Haverkort},
Publisher = {Springer},
Series = {Lecture Notes in Computer Science},
Volume = {9259},
Note = {Proceedings of the 12th International Conference on Quantitative Evaluation of Systems (QEST 2015), Madrid, Spain, September 1-3, 2015},
url = {http://www.springer.com/us/book/9783319222639},
doi={10.1007/978-3-319-22264-6}
}

S. Pérez, H. Facchini, A. Dantiacq, G. Cangemi, and J. Campos, “Analysis of Impact in the Wi-Fi QoS of the EDCA Parameters,” Journal of Computer Science & Technology, vol. 15, iss. 1, pp. 8-14, 2015.
[Bibtex]

@ARTICLE{PFDCC-JCST-15,
author = {S. P{\'e}rez and H. Facchini and A. Dantiacq and G. Cangemi and J. Campos},
title = {Analysis of Impact in the {Wi-Fi QoS} of the {EDCA} Parameters},
journal = {Journal of Computer Science \& Technology},
year = {2015},
volume = {15},
pages = {8-14},
number = {1},
month = {April},
abstract = {With the continuing development of the wireless technologies
(Wi-Fi, 3G, 4G, WiMax and Bluethooth), the study of wireless multimedia
transmissions has gained lately more attention. For example, the expectations
of the company leaders on the growth of Wi-Fi video traffic has updated the
lines of research on the standard IEEE 802.11e introduced to provide QoS
(Quality of Service) to WLAN (Wireless LAN ) networks. In this paper we
updated with greater accuracy, using other resources and the experience
gained since the emergence of the standard, the work carried out previously
on the quantitative impact of each EDCA (Enhanced Distributed Channel Access)
parameter on the overall performance of the mechanisms MAC. A quantitative
analysis of the optimizations that can be achieved has been performed by
simulation. We use a node model EDCA 802.11e with the tool M{\"o}bius of the
University of Illinois, which supports an extension of SPN (Stochastic Petri
Networks), known as HSAN (Hierarchical Stochastic Activity Networks), what
favors the contrast with other tools or mathematical resources. We use a
realistic scenario formed by Wi-Fi stations with the capacity to transmit
voice, video and best effort traffic. The results show that the default
setting of EDCA parameters is not optimal, and that with an appropriate
selection, very significant improvements can be obtained.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pfdcc-jcst-15.pdf},
doi={}
}

S. Pérez, H. Facchini, A. Dantiacq, G. Cangemi, and J. Campos, “An Evaluation of QoS for intensive video traffic over 802.11e WLANs,” in Proceedings of the 25th International Conference on Electronics, Communications and Computers (CONIELECOMP’15), Puebla, Mexico, 2015, pp. 8-15.
[Bibtex]

@INPROCEEDINGS{PFDCC-CONIELECOMP-15,
author = {S. P{\'e}rez and H. Facchini and A. Dantiacq and G. Cangemi and J. Campos},
title = {An Evaluation of {QoS} for intensive video traffic over 802.11e {WLANs}},
booktitle = {Proceedings of the 25th International Conference on Electronics, Communications and Computers {(CONIELECOMP'15)}},
year = {2015},
pages = {8-15},
address = {Puebla, Mexico},
month = {February},
publisher = {IEEE Computer Society},
abstract = {With the continuing development of the wireless
technologies (Wi-Fi, 3G, 4G, WiMax and Bluethooth), the study
of wireless multimedia transmissions has gained lately more
attention. For example, the expectations of the company leaders
on the growth of Wi-Fi video traffic has updated the lines of
research on the standard IEEE 802.11e introduced to provide
QoS (Quality of Service) to WLAN (Wireless LAN ) networks. A
quantitative analysis has been performed by simulation. We use a
node model EDCA (Enhanced Distributed Channel Access)
802.11e with the tool M{\"o}bius of the University of Illinois, which
supports an extension of SPN (Stochastic Petri Networks), known
as HSAN (Hierarchical Stochastic Activity Networks). This
formalism favors the comparison of the results with those
obtained from other tools, based mainly on simulation languages,
for Wi-Fi stations with the capacity to transmit voice, video or
best effort traffic in presence of error. This article introduces
novel scenario that varies the load by increasing the number of
active stations from 5 to 45 but maintaining their relative traffic
proportion. The proportion of traffic injected by stations is 65\%
video, 2\% voice, and 33\% best effort. Measured performance
metrics were absolute or direct performance, relative
performance, average delay of queue, and average queue size.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pfdcc-conielecomp-15.pdf},
doi={10.1109/CONIELECOMP.2015.7086933}
}

Formal Methods in Manufacturing, J. Campos, C. Seatzu, and X. Xie, Eds., CRC Press, 2014. [Publisher URL]
[Bibtex]

@BOOK{CSX-FMM-Book-2014,
title = {Formal Methods in Manufacturing},
publisher = {CRC Press},
year = {2014},
editor = {J. Campos and C. Seatzu and X. Xie},
abstract = {Design and operation of manufacturing systems and their supply chains is a domain of significant
research worldwide. The complexity of this domain stems from the large dimension of such systems
that are highly parallel and distributed, from significant sources of uncertainties and from the degrees
of flexibility. Formal methods are mathematical techniques, often supported by tools, for developing
man-made systems. Formal methods and mathematical rigor enable manufacturing engineers to
handle fundamental design principles, such as abstraction or modular and hierarchical development,
and to deal with typical engineering problems and quality goals, like reliability, flexibility, and
maintainability. Formal methods can provide both a deep understanding of the system, thus helping
to cover holes in the specification, and an improved system reliability, through verification and
validation of the desired properties. Automata, statecharts, queueing networks, Petri nets, min-max
algebras, process algebras, and temporal logic-based models are becoming more and more used for
an integrated view of design specification, validation, performance evaluation, planning, scheduling
and control of manufacturing systems and their supply chains.
This book presents some of the most significant works representing the state of the art in the
area of formal methodologies for manufacturing systems, combining fundamentals and advanced
issues. It is divided into four main parts, each devoted to a specific issue: modelling and simulation,
supervisory control (including deadlock prevention), performance evaluation (including scheduling
and optimization), and fault diagnosis and reconfiguration. Several formalisms are considered,
including finite state automata, Petri nets (discrete, timed, continuous, and hybrid), process algebra
and max-plus algebra, exemplifying the advantages of each of them in the solution of a specific
problem.Within each part, more detailed problems are considered, and themost significant solutions
are discussed and illustratedwith a series of interesting and significant examples in themanufacturing
area. Individual chapters are written by leading experts in the field. Each topic is illustrated in detail,
its significance in manufacturing systems is underlined, and the most important contributions
in that specific area are surveyed.
The book is intended for researchers, postgraduate students and engineers interested in problems
occurring in manufacturing systems. In particular, it provides a comprehensive overview of the most
important formal model-based solutions to a series of major problems in manufacturing systems and
their supply chains, which are based on formal and rigorous modelling of the underlying system.
Each chapter in the book aims at providing a balance mixture of (1) fundamental theory, giving
the reader a clear introduction to the most important formalisms used for the modelling, analysis
and control of manufacturing systems; (2) tutorial value, providing the state of the art on a series
of problems that occur in manufacturing systems, such as deadlock prevention, supervisory control,
performance evaluation and fault diagnosis; and (3) applicability, presenting a series of case studies
and applications taken from the industrial world, that make it particularly appealing to practitioners.
A brief description of the book is as follows. Part I (Chapters 1 through 5) concerns modelling
and simulation of manufacturing systems. Chapter 1 focuses on Petri nets (untimed and timed) and
shows how these can be effectively used to represent manufacturing systems in a bottom-up and
modular fashion. Chapter 2 deals with a particular class of manufacturing systems for which a
linear representation in an algebraic structure called dioids can be given. Chapters 3 and 4 deal
with hybrid models of manufacturing systems. In particular, Chapter 3 focuses on hybrid Petri nets
(HPNs), a formalism that combines fluid and discrete event dynamics. Particular attention is devoted
to first-order hybrid Petri nets (FOHPNs) whose continuous dynamics are piecewise constant. It is
shown how FOHPNs can be effectively used to model both manufacturing systems and inventory
control systems. Chapter 4 focuses on stochastic flow models (SFMs) that preserve the essential
features needed to design effective controllers and potentially optimize performance without any need
to estimate the corresponding optimal performance value with accuracy. An overview of recently
developed general frameworks for infinitesimal perturbation analysis (IPA) is also presented, through
which unbiased performance sensitivity estimates of typical manufacturing performance measures
can be obtained in such SFMs with respect to various controllable parameters of interest. Finally,
Chapter 5 deals with a problem occurring in many real manufacturing systems, namely, freight
transportation. It reviews the established transportation system modelling, including theory and
applications of transportation supply models, trip demand models and dynamic traffic assignment
methods, both for passenger and freight transportation, and also points out the characteristics of
freight transportation that influence the logistic chain performance.
Part II (Chapters 6 through 12) is devoted to the supervisory control of manufacturing systems.
In particular, Chapters 6 through 8 introduce deadlock avoidance/prevention policies; Chapters 9
through 12 deal with supervisory control problems. Chapter 6 addresses the problem of deadlock
avoidance in flexibly automated manufacturing systems through the modelling abstraction of the
(sequential) resource allocation system (RAS). The pursued analysis uses concepts and results from
the formalmodelling framework of finite state automata (FSA). Chapter 7 investigates the problem of
deadlock prevention in the Petri net framework. After an overview of the classical approaches based
on the addition of monitors that prevent siphons to become empty, a novel methodology is presented.
Chapter 8 also deals with Petri nets. Here the digraph theory is used to effectively derive control
laws that avoid deadlocks in single unit RAS, that is, systems where each part requires a single unit
of a single resource for each operation. In Chapter 9, Petri nets are used to solve supervisory control
problems of manufacturing systems. Different problem statements, depending on the considered
specifications, and different solutions are considered, in particular based on the theory of monitor
places and on the theory of regions. Extended finite automata (EFA), that is, automata augmented
with bounded discrete variables, and updates of these variables on the transitions, are introduced
in Chapter 10 and effectively used to automatically synthesize a supervisor. Decentralized control
and modular control problems are discussed in Chapter 11. Finally, Chapter 12 discusses how
manufacturing systems can often be modeled as max-plus-linear (MPL) systems and controlled via
model predictive control (MPC).
Part III (Chapters 13 through 20) addresses the issue of performance evaluation of manufacturing
systems and supply chains. Chapter 13 discusses approaches based on coloured Petri nets and
state space analysis. Performance evaluation and control of manufacturing systems using fluid (i.e.,
continuous) Petri nets are discussed in Chapter 14. Chapter 15, discusses how timed process algebra
called bounded true concurrency (BTC) can be effectively used for performance evaluation of flexible
manufacturing systems. The problem of designing the lean, that is, the smallest buffers necessary and
sufficient to achieve the desired line performance, is addressed in Chapter 16. Chapter 17 deals with
the issue of inventory allocation and cycle time improvement in manufacturing systems and supply
chains. Chapter 18 covers timed weighted event graphs, a subclass of Petri nets whose transitions
are associated with workshops or specific treatments and whose places represent storages between
the transitions. It deals with the minimization of the overall capacities of places, under throughput constraints.
Chapter 19 focuses on the application of Petri nets to the scheduling of semiconductor manufacturing systems.
To this aim, a hierarchical coloured timed Petri net (HCTPN) is proposed and genetic algorithms
are extended and then embedded into the constructed HCTPN to find optimal/suboptimal schedules.
Finally, Chapter 20 focuses on organization problems of health-care systems, presenting a Petri
net-based software for health-care service modelling and simulation called MedPRO. Resource
planning and scheduling are also in the scope of the tool.
Finally, Part IV (Chapters 21 through 23) illustrates fault diagnosis approaches for discrete event
systems that can be successfully applied to manufacturing systems. In particular, in Chapters 21 and
22 finite state automata and interpreted Petri nets, respectively, are used as reference formalisms.
In both chapters, diagnosability analysis is also performed. Chapter 21 also discusses the problem
of sensor selection for diagnosability and the problem of cooperative diagnosis for systems with
decentralized information. Chapter 23 addresses a problem strictly related to fault diagnosis occurring
in automated manufacturing systems, namely, that of online control reconfiguration.},
url = {http://www.crcpress.com/product/isbn/9781466561557},
doi={10.1201/b16529}
}

S. Pérez, J. Campos, H. Facchini, and L. Bisaro, “Tuning Mechanism for IEEE 802.11e EDCA Optimization,” IEEE Latin America Transactions, vol. 11, iss. 4, pp. 1134-1142, 2013.
[Bibtex]

@ARTICLE{PCFB-LAT-13,
author = {S. P{\'e}rez and J. Campos and H. Facchini and L. Bisaro},
title = {Tuning Mechanism for {IEEE 802.11e EDCA} Optimization},
journal = {IEEE Latin America Transactions},
year = {2013},
volume = {11},
pages = {1134-1142},
number = {4},
month = {June},
abstract = {The overall performance of a WLAN 802.11e is
determined, among other things, by the Enhanced Distributed
Channel Access (EDCA) parameters, typically configured with
default and static values. The same does not vary according to
the dynamic requirements of Quality of Service (QoS) of the
network. To achieve significant improvements in the
performance of the network, and simultaneously comply with the
specifications of QoS, a new algorithm of tuning is proposed to
make the adjustment of these parameters dynamically, which we
call Algorithm for the Differentiation of Traffic Multiple
(MTDA). The algorithm has been evaluated in realistic scenarios
with noise, reaching a initialization effective, rapid convergence,
and the differentiation of effective multiple wireless traffic (voice,
video and best effort with Pareto distribution). It adopted a
model of wireless station implemented in Hierarchical Stochastic
Activities Networks (HSANs), which runs on the simulator
M{\"o}bius.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pcfb-lat-13.pdf},
doi={10.1109/TLA.2013.6601760}
}

S. Bernardi and J. Campos, “A min-max problem for the computation of the cycle time lower bound in interval-based Time Petri Nets,” IEEE Transactions on Systems, Man, and Cybernetics: Systems, vol. 43, iss. 5, pp. 1167-1181, 2013.
[Bibtex]

@ARTICLE{BC-TSMC-13,
author = {S. Bernardi and J. Campos},
title = {A min-max problem for the computation of the cycle time lower bound in interval-based {Time} {Petri} {Nets}},
journal = {IEEE Transactions on Systems, Man, and Cybernetics: Systems},
year = {2013},
volume = {43},
pages = {1167-1181},
number = {5},
month = {September},
abstract = {The Time Petri Net with firing frequency intervals (TPNF) is a modeling formalism used
to specify system behavior under timing and frequency constraints.
Efficient techniques exist to evaluate the performance of TPNF models based on the
computation of bounds of performance metrics (e.g., transition throughput, place marking).
In this paper, we propose a min-max problem to compute the cycle time of a transition
under optimistic assumptions. That is, we are interested in computing the lower bound.
We will demonstrate that such a problem is related to a maximization linear programming
problem (LP-max) previously stated in the literature,
to compute the throughput upper bound of the transition.
The main advantage of the min-max problem compared to the LP-max is that, besides the
optimal value, the optimal solutions provide useful feedback to the analyst
on the system behavior (e.g., performance bottlenecks).
We have implemented two solution algorithms, using CPLEX APIs,
to solve the min-max problem, and have
compared their performance using a benchmark of TPNF models,
several of these being case studies.
Finally, we have applied the min-max technique for the vulnerability
analysis of a critical infrastructure, i.e., the Saudi Arabian crude-oil distribution network.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/bc-tsmc-13.pdf},
doi = {10.1109/TSMCA.2012.2226442}
}

S. Bernardi and J. Campos, “A min-max problem for the computation of the cycle time lower bound in interval-based Time Petri Nets,” in Actas de las XXI Jornadas de Concurrencia y Sistemas Distribuidos, San Sebastián, Spain, 2013.
[Bibtex]

@INPROCEEDINGS{BC-JCSD13,
author = {S. Bernardi and J. Campos},
title = {A min-max problem for the computation of the cycle time lower bound in interval-based {Time} {Petri} {Nets}},
booktitle = {Actas de las {XXI} Jornadas de Concurrencia y Sistemas Distribuidos},
year = {2013},
address = {San Sebasti{\'a}n, Spain},
month = {June},
publisher = {Universidad del Pa\'{\i}s Vasco},
abstract = {The Time Petri Net with firing frequency intervals (TPNF) is a modeling formalism used
to specify system behavior under timing and frequency constraints.
Efficient techniques exist to evaluate the performance of TPNF models based on the
computation of bounds of performance metrics (e.g., transition throughput, place marking).
In this paper, we propose a min-max problem to compute the cycle time of a transition
under optimistic assumptions. That is, we are interested in computing the lower bound.
We will demonstrate that such a problem is related to a maximization linear programming
problem (LP-max) previously stated in the literature,
to compute the throughput upper bound of the transition.
The main advantage of the min-max problem compared to the LP-max is that, besides the
optimal value, the optimal solutions provide useful feedback to the analyst
on the system behavior (e.g., performance bottlenecks).
We have implemented two solution algorithms, using CPLEX APIs,
to solve the min-max problem, and have
compared their performance using a benchmark of TPNF models,
several of these being case studies.
Finally, we have applied the min-max technique for the vulnerability
analysis of a critical infrastructure, i.e., the Saudi Arabian crude-oil distribution network.},
note = {See the paper \cite{BC-TSMC-13}},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/bc-jcsd13.pdf},
doi={}
}

S. Pérez, H. Facchini, G. Mercado, L. Bisaro, and J. Campos, “Throughput Quantitative Analysis of EDCA 802.11e in Different Scenarios,” Journal of Computer Science & Technology, vol. 13, iss. 1, pp. 16-23, 2013.
[Bibtex]

@ARTICLE{PFMBC-JCST-13,
author = {S. P{\'e}rez and H. Facchini and G. Mercado and L. Bisaro and J. Campos},
title = {Throughput Quantitative Analysis of {EDCA} 802.11e in Different Scenarios},
journal = {Journal of Computer Science \& Technology},
year = {2013},
volume = {13},
pages = {16-23},
number = {1},
month = {April},
abstract = {This document presents a quantitative analysis of the direct and relative throughput of IEEE 802.11e.
The global throughput of an 802.11e WLAN is determined by EDCA (Enhanced Distributed Channel Access)
parameters, among other aspects, that are usually configured with predetermined and static values. This
study carefully evaluates the Quality of Service (QoS) of Wi-Fi with EDCA in several realistic scenarios with noise
and a blend of wireless traffic (e.g., voice, video, and best effort, with Pareto distribution). The metrics of the
benefits obtained in each case are compared, and the differentiated impact of network dynamics on each case is
quantified. The results obtained show that the default settings are not optimal, and that with an appropriate
selection, can be achieved improvements of the order of 25%, according to the type of traffic. In addition, it could
be shown the quantitative impact of each parameter EDCA on the overall performance. This study proposes a new
experimental scenario based on the relative proportion of traffic present in the network. Stations have been
simulated using the M{\"o}bius tool, which supports an extension of SPN (Stochastic Petri Networks), known as
HSAN (Hierarchical Stochastic Activity Networks).},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pfmbc-jcst-13.pdf},
doi={}
}

S. Pérez, H. Facchini, G. Mercado, L. Bisaro, and J. Campos, “EDCA 802.11e performance under different scenarios. Quantitative analysis,” in Proceedings of the 27th International Conference on Advanced Information Networking and Applications (AINA’13), Barcelona, Spain, 2013, pp. 802-807.
[Bibtex]

@INPROCEEDINGS{PFMBC-AINA-13,
author = {S. P{\'e}rez and H. Facchini and G. Mercado and L. Bisaro and J. Campos},
title = {{EDCA} 802.11e performance under different scenarios. Quantitative analysis},
booktitle = {Proceedings of the 27th International Conference on Advanced Information Networking and Applications {(AINA'13)}},
year = {2013},
pages = {802-807},
address = {Barcelona, Spain},
month = {March},
publisher = {IEEE Computer Society},
abstract = {The global throughput of an 802.11e WLAN is determined by EDCA (Enhanced Distributed Channel Access) parameters, among other aspects, that are usually configured with predetermined and static values. This study carefully evaluates the Quality of Service (QoS) of Wi-Fi with EDCA in several realistic scenarios with noise and a blend of wireless traffic (e.g., voice, video, and best effort, with Pareto distribution). The metrics of the benefits obtained in each case are compared, and the differentiated impact of network dynamics on each case is quantified. This study proposes a new experimental scenario based on the relative proportion of traffic present in the network. Stations have been implemented using HSANs (Hierarchical Stochastic Activity Networks) and simulated using the M\"obius tool.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pfmbc-aina-13.pdf},
doi={10.1109/AINA.2013.20}
}

S. Bernardi, J. Campos, and J. Merseguer, “Timing-failure risk assessment of UML design using Time Petri Net bound techniques,” IEEE Transactions on Industrial Informatics, vol. 7, iss. 1, pp. 90-104, 2011.
[Bibtex]

@ARTICLE{BCM-TII-11,
author = {S. Bernardi and J. Campos and J. Merseguer},
title = {Timing-failure risk assessment of {UML} design
using {Time} {Petri} {Net} bound techniques},
journal = {IEEE Transactions on Industrial Informatics},
year = {2011},
volume = {7},
pages = {90-104},
number = {1},
month = {February},
abstract = {Software systems that do not meet their timing constraints
can cause risks. In this work we propose a comprehensive
method for assessing the risk of timing failure by evaluating the
software design. We show how to apply best practises in software engineering
and well-known Time Petri Net (TPN) modeling and analysis
techniques, and we demonstrate the effectiveness of the
method with reference to a case study in the domain of realtime
embedded systems. The method customizes the Australian standard risk
management process, where the system context is the UML-based
software specification, enriched with standard MARTE profile
annotations to capture non-functional system properties. During
the risk analysis, a TPN is derived, via model transformation,
from the software design specification and TPN bound techniques
are applied to estimate the probability of timing failure. TPN
bound techniques are also exploited, within the risk evaluation
and treatment steps, to identify the risk causes in the software
design.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/bcm-tii-11.pdf},
doi = {10.1109/TII.2010.2098415}
}

J. Campos, “Guest Editorial: Special Section on Formal Methods in Manufacturing,” IEEE Transactions on Industrial Informatics, vol. 6, iss. 2, pp. 125-126, 2010.
[Bibtex]

@ARTICLE{Cam-TII-10,
author = {J. Campos},
title = {Guest Editorial: {Special Section on Formal Methods in Manufacturing}},
journal = {IEEE Transactions on Industrial Informatics},
year = {2010},
volume = {6},
pages = {125-126},
number = {2},
month = {May},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cam-tii-10.pdf},
doi={10.1109/TII.2010.2042529}
}

Proceedings of the 14th IEEE International Conference on Emerging Technologies and Factory Automation, A. Grau, J. Campos, and G. Oliver, Eds., Palma de Mallorca, Spain: IEEE Industrial Electronics Society, 2009. [Publisher URL]
[Bibtex]

@Book{ETFA-09,
title = {Proceedings of the 14th IEEE International Conference on Emerging
Technologies and Factory Automation},
year = {2009},
editor = {Antoni Grau and Javier Campos and Gabriel Oliver},
address = {Palma de Mallorca, Spain},
publisher = {IEEE Industrial Electronics Society},
month = {September},
url = {http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=5340902},
doi={}
}

S. Bernardi and J. Campos, “Computation of Performance Bounds for Real-Time Systems Using Time Petri Nets,” IEEE Transactions on Industrial Informatics, vol. 5, iss. 2, pp. 168-180, 2009.
[Bibtex]

@ARTICLE{BC-TII-09,
author = {S. Bernardi and J. Campos},
title = {Computation of Performance Bounds for Real-Time Systems Using Time
{Petri} Nets},
journal = {IEEE Transactions on Industrial Informatics},
year = {2009},
volume = {5},
pages = {168-180},
number = {2},
month = {May},
abstract = {Time Petri Nets (TPNs) have been widely used for the verification
and validation of real-time systems during the software development
process. Their quantitative analysis consists in applying enumerative
techniques that suffer the well known state space explosion problem.
To overcome this problem several methods have been proposed in the
literature, that either provide rules to obtain equivalent nets with
a reduced state space or avoid the construction of the whole state
space. In this paper, we propose a method that consists in computing
performance bounds to predict the average operational behavior of
TPNs by exploiting their structural properties and by applying operational
laws. Performance bound computation was first proposed for Timed
(Timed PNs) and Stochastic Petri nets (SPNs). We generalize the results
obtained for Timed PNs and SPNs to make the technique applicable
to TPNs and their extended stochastic versions: TPN with firing frequency
intervals (TPNFs) and Extended TPNs (XTPNs). Finally, we apply the
proposed bounding techniques on the case study of a robot-control
application taken from the literature.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/bc-tii-09.pdf},
doi = {10.1109/TII.2009.2017201}
}

C. J. Pérez-Jiménez, J. Campos, and M. Silva, “Approximate Throughput Computation of Stochastic Weighted T-Systems,” IEEE Transactions on Systems, Man, and Cybernetics. Part A: Systems and Humans, vol. 37, iss. 3, pp. 431-444, 2007.
[Bibtex]

@ARTICLE{PJCS-TSMC-07,
author = {C.J. P{\'e}rez-Jim{\'e}nez and J. Campos and M. Silva},
title = {Approximate Throughput Computation of Stochastic Weighted {T}-Systems},
journal = {IEEE Transactions on Systems, Man, and Cybernetics. Part A: Systems
and Humans},
year = {2007},
volume = {37},
pages = {431-444},
number = {3},
month = {May},
abstract = {A general iterative technique for approximate throughput computation
of stochastic live and bounded weighted T-systems is presented. It
generalizes a previous technique on stochastic marked graphs. The
approach has two basic foundations. First, a deep understanding of
the qualitative behaviour of weighted T-systems leads to a general
decomposition technique. Second, after the decomposition phase, an
iterative response time approximation method is applied for the throughput
computation. Existence of convergence points for the iterative approximation
method can be proved. Experimental results generally have an error
of less than 5%. The state space is usually reduced by more than
one order of magnitude; therefore, the analysis of otherwise intractable
systems is possible.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pjcs-tsmc-07.pdf},
doi={10.1109/TSMCA.2007.893455}
}

J. Campos and J. Merseguer, “On the integration of UML and Petri nets in software development,” Lecture Notes in Computer Science, vol. 4024, pp. 19-36, 2006.
[Bibtex]

@ARTICLE{CM-LNCS-06,
author = {J. Campos and J. Merseguer},
title = {On the integration of {UML} and {Petri} nets in software development},
journal = {Lecture Notes in Computer Science},
year = {2006},
volume = {4024},
pages = {19-36},
note = {Invited paper},
abstract = {Software performance engineering deals with the consideration of quantitative
analysis of the behaviour of software systems from the early development
phases in the life cycle. This paper summarizes in a semiformal and
illustrative way our proposal for a suitable software performance
engineering process. We try to integrate in a very pragmatic approach
the usual object oriented methodology ---supported with UML language
and widespread CASE tools--- with a performance modelling formalism,
namely stochastic Petri nets. A simple case study is used to describe
the whole process. More technical details should be looked up in
the cited bibliography.},
booktitle = {Petri Nets and Other Models of Concurrency - ICATPN 2006: 27th International
Conference on Applications and Theory of Petri Nets and Other Models
of Concurrency, Turku, Finland, June 26-30, 2006},
editor = {S. Donatelli and P. S. Thiagarajan},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cm-lncs-06.pdf},
doi={10.1007/11767589_2}
}

S. Bernardi, J. Campos, S. Donatelli, and J. Merseguer, GSPN Compositional Semantics for UML Statecharts and Sequence Diagrams, 2005.
[Bibtex]

@UNPUBLISHED{BCDM-05,
author = {S. Bernardi and J. Campos and S. Donatelli and J. Merseguer},
title = {{GSPN} Compositional Semantics for {UML} Statecharts and Sequence
Diagrams},
note = {Submitted for publication},
year = {2005},
abstract = {Software performance engineering (SPE) is proposed as a method for
the performance evaluation of software systems early in the development
process. The generic approach of the SPE consists of deriving performance
models from UML specifications. This paper, following the SPE principles,
addresses the UML StateCharts (SCs) and the Sequence Diagrams (SDs)
as UML specifications, while performance models are specified with
Generalized Stochastic Petri Nets. The proposed derivation, actually
the authors interpretation of the SC and SD, provides these two kinds
of UML diagrams with a formal semantics. The interpretation is based
on the UML semi-formal semantics. A software fault tolerance mechanism
is used as an example to illustrate how, following the proposal,
the SC and the SD are automatically converted into GSPNs. Another
contribution of the work is the consistency study among the SC and
the SD, since they are used in a combined manner to obtain the target
performance model. The approach presented in this paper allows to
derive two kinds of performance models: one representing the behaviour
of the whole system and another representing the particular execution
described by a SD.}
}

C. J. Pérez-Jiménez, J. Campos, and M. Silva, Approximate Throughput Computation of Deterministic Systems of Sequential Processes: Application to Manufacturing Systems, 2005.
[Bibtex]

@UNPUBLISHED{PJCS-05,
author = {C.J. P{\'e}rez-Jim{\'e}nez and J. Campos and M. Silva},
title = {Approximate Throughput Computation of Deterministic Systems of Sequential
Processes: Application to Manufacturing Systems},
note = {Submitted for publication},
year = {2005},
abstract = {A general iterative technique for approximate throughput computation
of stochastic live and bounded Deterministic Systems of Sequential
Processes (DSSPs, a subclass of Petri nets) is presented. It generalizes
a previous technique on stochastic weighted T-systems. The approach
has two basic foundations. First, a deep understanding of the qualitative
behaviour of DSSPs leads to a general decomposition technique. Second,
after the decomposition phase, an iterative response time approximation
method is applied for the throughput computation. We apply the obtained
technique to the performance evaluation of manufacturing systems
modelled with Petri nets. Experimental results generally have an
error of less than 5 %. The state space is usually reduced by more
than one order of magnitude; therefore, the analysis of otherwise
intractable systems is possible.}
}

J. Merseguer and J. Campos, “Software Performance Modelling Using UML and Petri Nets,” Lecture Notes in Computer Science, vol. 2965, pp. 265-289, 2004.
[Bibtex]

@ARTICLE{MC-LNCS-04,
author = {J. Merseguer and J. Campos},
title = {Software Performance Modelling Using {UML} and {Petri} Nets},
journal = {Lecture Notes in Computer Science},
year = {2004},
volume = {2965},
pages = {265-289},
note = {Invited paper},
abstract = {Software systems are today one of the most complex artifacts, they
are simultaneously used by hundred-thousand of people sometimes in
risk real time operations, such as auctions or electronic commerce.
Nevertheless, it is a common practice to deploy them without the
expected performance. Software Performance Engineering has emerged
as a discipline to complement Software Engineering research in order
to address this kind of problems. In this work, we survey some recent
contributions in the field of Software Performance Engineering. The
approach surveyed has as main features that it uses the UML diagrams
to specify the functional and performance requeriments of the system
and the stochastic Petri nets formalism to analyse it.},
booktitle = {Performance Tools and Applications to Networked Systems, Revised
Tutorial Lectures from {MASCOTS} 2003},
editor = {M.C. Calzarossa and E. Gelenbe},
publisher = {Springer-Verlag},
series = {Tutorials},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mc-lncs-04.pdf},
doi={10.1007/978-3-540-24663-3_13}
}

S. Bernardi and J. Campos, “On Performance Bounds for Interval Time Petri Nets,” in Proceedings of the 1st International Conference on Quantitative Evaluation of Systems (QEST’04), Enschede, The Netherlands, 2004, pp. 50-59.
[Bibtex]

@INPROCEEDINGS{BC-QEST-04,
author = {S. Bernardi and J. Campos},
title = {On Performance Bounds for Interval Time {Petri} Nets},
booktitle = {Proceedings of the 1st International Conference on Quantitative Evaluation
of Systems {(QEST'04)}},
year = {2004},
pages = {50-59},
address = {Enschede, The Netherlands},
month = {September},
publisher = {IEEE Computer Society},
abstract = {Interval time Petri Nets are Petri nets in which time intervals are
associated to transitions. Their quantitative analysis basically
consists in applying enumerative techniques that suffer the well
known state space explosion problem. To overcome this problem several
methods have been proposed in the literature, that either allow to
obtain equivalent nets with a reduced state space or avoid the construction
of the whole state space. The alternative method proposed here consists
in computing performance bounds to partially characterize the quantitative
behavior of interval time Petri Nets by exploiting their structural
properties and/or by applying operational laws. The performance bound
computation is not a new technique: it has been proposed for timed
Petri nets. In this paper we present the results obtained from a
preliminary investigation on the applicability of bounding techniques
of timed Petri nets to interval time Petri Nets.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/bc-qest-04.pdf},
doi = {10.1109/QEST.2004.1348019}
}

C. González-Buesa and J. Campos, “Solving the Mobile Robot Localization Problem Using String Matching Algorithms,” in Proceedings of the 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS’04), Sendai, Japan, 2004, pp. 2475-2480.
[Bibtex]

@INPROCEEDINGS{GBC-IROS-04,
author = {C. Gonz{\'a}lez-Buesa and J. Campos},
title = {Solving the Mobile Robot Localization Problem Using String Matching
Algorithms},
booktitle = {Proceedings of the 2004 {IEEE/RSJ} International Conference on Intelligent
Robots and Systems {(IROS'04)}},
year = {2004},
pages = {2475-2480},
address = {Sendai, Japan},
month = {September},
abstract = {In this paper we address the mobile robot localization using some
techniques borrowed from the Computational Biology community. The
specific problem studied here is also known as the kidnapped robot
problem. Our proposal is to solve this problem by string matching
algorithms, which have experienced a large advance in the last years
due to (for example) the Genoma Project. The paper uses three different
algorithms to solve the mentioned problem and shows their advantages,
such as the robustness of the results and the memory and time efficiency.
These results are validated by real experimentation using panoramic
images of indoor buildings, and compared and discussed with existing
techniques that have been used over the same test-bed.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/gbc-iros-04.pdf},
doi={10.1109/IROS.2004.1389780}
}

J. P. López-Grao, J. Merseguer, and J. Campos, “From UML Activity Diagrams to Stochastic Petri Nets: Application to Software Performance Engineering,” in Proceedings of the Fourth International Workshop on Software and Performance (WOSP’04), Redwood City, California, USA, 2004, pp. 25-36.
[Bibtex]

@INPROCEEDINGS{LGMC-WOSP04,
author = {J.P. L{\'o}pez-Grao and J. Merseguer and J. Campos},
title = {From {UML} Activity Diagrams to Stochastic {Petri} Nets: Application
to Software Performance Engineering},
booktitle = {Proceedings of the Fourth International Workshop on Software and
Performance {(WOSP'04)}},
year = {2004},
pages = {25-36},
address = {Redwood City, California, USA},
month = {January},
publisher = {ACM},
note = {Also in ACM SIGSOFT Software Engineering Notes, Vol. 29, no. 1, January
2004.},
abstract = {Over the last decade, the relevance of performance evaluation in the
early stages of the software development life-cycle has been steadily
rising. We honestly believe that the integration of formal models
in the software engineering process is a must, in order to enable
the application of well-known, powerful analysis techniques to software
models. In previous papers the authors have stated a proposal for
SPE, dealing with several UML diagram types.The proposal formalizes
their semantics, and provides a method to translate them into (analyzable)
GSPN models. This paper focuses on activity diagrams, which had not
been dealt with so far. They will be incorporated in our SPE method,
enhancing its expressivity by refining abstraction levels in the
statechart diagrams. Performance requirements will be annotated according
to the UML profile for schedulability, performance and time. Last
but not least, our CASE tool prototype will be introduced. This tool
deals with every model element from activity diagrams and ensures
an automatic translation from ADs into GSPNs strictly following the
process related in this paper.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/lgmc-wosp04.pdf},
doi={10.1145/974044.974048}
}

J. Merseguer, J. Campos, and E. Mena, “Analysing Internet Software Retrieval Systems: Modeling and Performance Comparison,” Wireless Networks: The Journal of Mobile Communication, Computation and Information, vol. 9, iss. 3, pp. 223-238, 2003.
[Bibtex]

@ARTICLE{MCM-WINET03,
author = {J. Merseguer and J. Campos and E. Mena},
title = {Analysing Internet Software Retrieval Systems: Modeling and Performance
Comparison},
journal = {Wireless Networks: The Journal of Mobile Communication, Computation
and Information},
year = {2003},
volume = {9},
pages = {223-238},
number = {3},
month = {May},
abstract = {Nowadays, there exist web sites that allow users to retrieve and install
software in an easy way. The performance of these sites may be poor
if they are used in wireless networks; the reason is the inadequate
use of the net resources that they need. If this kind of systems
are designed using mobile agent technology the previous problem might
be avoided. In this paper, we present a comparison between the performance
of a software retrieval system especially designed to be used in
a wireless network and the performance of a software retrieval system
similar to the well-known Tucows.com web site. In order to compare
performance, we make use of a software performance process enriched
with formal techniques. The process has as important features that
it uses UML as a design notation and it uses stochastic Petri nets
as formal model. Petri nets provide a formal semantics for the system
and a performance model.},
publisher = {Kluwer Academic Publishers},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mcm-winet03.pdf},
doi={10.1023/A:1022825210932}
}

J. Merseguer and J. Campos, “Exploring Roles for the UML Diagrams in Software Performance Engineering,” in Proceedings of the 2003 International Conference on Software Engineering Research and Practice (SERP’03), Las Vegas, Nevada, USA, 2003, pp. 43-47.
[Bibtex]

@INPROCEEDINGS{MC-SERP03,
author = {J. Merseguer and J. Campos},
title = {Exploring Roles for the {UML} Diagrams in Software Performance Engineering},
booktitle = {Proceedings of the 2003 International Conference on Software Engineering
Research and Practice {(SERP'03)}},
year = {2003},
pages = {43-47},
address = {Las Vegas, Nevada, USA},
month = {June},
publisher = {CSREA Press},
abstract = {It is not an overstatement to say that the gap between software design
and performance evaluation techniques has caused the misuse of the
last ones by software engineers. The UML profile for schedulability,
performance and time arose from the intention to close both fields,
software engineering and performance analysis. Nevertheless the gap
remains, since it is difficult for software engineers to devise which
parts of their designs are suitable to represent performance requirements.
The profile has started to study this problem from a scenarios viewpoint.
In this work, we explore other viewpoints to deal with performance
requirements at software design level.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mc-serp03.pdf},
doi={}
}

J. Merseguer, J. Campos, and E. Mena, “A Pattern-Based Approach to Model Software Performance Using UML and Petri Nets: Application to Agent-Based Systems,” in Proceedings of the 7th World Multiconference on Systemics, Cybernetics and Informatics, Orlando, Florida, USA, 2003, pp. 307-313.
[Bibtex]

@INPROCEEDINGS{MCM-SCI03,
author = {J. Merseguer and J. Campos and E. Mena},
title = {A Pattern-Based Approach to Model Software Performance Using {UML}
and {Petri} Nets: Application to Agent-Based Systems},
booktitle = {Proceedings of the 7th World Multiconference on Systemics, Cybernetics
and Informatics},
year = {2003},
volume = {IX},
pages = {307-313},
address = {Orlando, Florida, USA},
month = {July},
publisher = {IIIS Press},
abstract = {Software design and implementation using mobile agents are nowadays
involved in a scepticism halo. There are researchers who question
its utility because it could be a new technology that does provide
new skills but it could introduce new problems. Security and performance
are the most critical aspects for this new kind of software. In this
paper we present a formal approach to analyse performance for this
class of systems, which is integrated in the early stages of the
software development process. We propose to model the software system
in a pragmatic way using as a design technique the well-known design
patterns; from these models, the corresponding formal performance
model, in terms of Petri nets, is obtained semi-automatically by
applying a set of translation rules. Therefore, the formal performance
model is obtained as a by-product of the software life-cycle, preserving
the benefits of the software design techniques. Finally, the formal
performance model is analysed, using analytical techniques, in order
to study the performance of the system. Moreover, another benefit
of the proposal is that it is possible to predict the behaviour of
the system without the necessity of implementing it. To illustrate
the proposal, we apply it to a software retrieval service system
designed using mobile agents.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mcm-sci03.pdf},
doi={}
}

A. González-Uzábal, C. Galé, and J. Campos, “Desarrollo de una herramienta de optimización binivel utilizando CPLEX y MATLAB y generación de problemas de prueba,” in Actas del 27 Congreso Nacional de Estadística e Investigación Operativa, Lleida, Spain, 2003, pp. 2931-2944.
[Bibtex]

@INPROCEEDINGS{GUGC-SEIO03,
author = {A. Gonz{\'a}lez-Uz{\'a}bal and C. Gal{\'e} and J. Campos},
title = {Desarrollo de una herramienta de optimizaci\'on binivel utilizando
{CPLEX} y {MATLAB} y generaci\'on de problemas de prueba},
booktitle = {Actas del 27 Congreso Nacional de Estad\'{\i}stica e Investigaci\'on
Operativa},
year = {2003},
pages = {2931-2944},
address = {Lleida, Spain},
month = {April},
organization = {Sociedad de Estad\'{\i}stica e Investigaci\'on Operativa de Espa\~na
y Departament de Matem\`atica de la Universidad de Lleida},
publisher = {Edicions de la Universitat de Lleida},
note = {In Spanish},
abstract = {En este trabajo se presenta el desarrollo de una herramienta para
resolver problemas de optimizaci\'on binivel y en particular de un
nivel, tanto con objetivos lineales como lineales fraccionarios,
implementada en CPLEX y en MATLAB. La herramienta permite seleccionar
entre varios algoritmos de resoluci\'on y obtener medidas de evaluaci\'on
del rendimiento de cada uno. Se presenta tambi\'en un m\'etodo para
la generaci\'on autom\'atica de problemas binivel de prueba que ayude
a evaluar este tipo de herramientas. Mediante una serie de transformaciones
de la matriz de coeficientes tecnol\'ogicos y la funci\'on objetivo
de segundo nivel, se asegura la factibilidad del problema y que la
soluci\'on del problema binivel no sea la trivial.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/gugc-seio03.pdf},
doi={}
}

J. P. López-Grao, J. Merseguer, and J. Campos, “Performance Engineering Based on UML and SPNs: A Software Performance Tool,” in Proceedings of the Seventeenth International Symposium on Computer and Information Sciences, Orlando, Florida, USA, 2002, pp. 405-409.
[Bibtex]

@INPROCEEDINGS{LGMC-02c,
author = {J.P. L{\'o}pez-Grao and J. Merseguer and J. Campos},
title = {Performance Engineering Based on {UML} and {SPNs}: A Software Performance
Tool},
booktitle = {Proceedings of the Seventeenth International Symposium on Computer
and Information Sciences},
year = {2002},
pages = {405-409},
address = {Orlando, Florida, USA},
month = {October},
organization = {University of Central Florida},
publisher = {CRC Press},
abstract = {The increasing relevance of UML as a semi-formal modelling paradigm
has entailed the need for an adjustment of the classical performance
evaluation methods within the scope of the new working environment.
Under these circumstances, a formal semantics for the UML language
and a strong mathematical substratum are required in order to be
able to compute performance estimates and validate logical properties
in the first stages of the software life-cycle. We believe that stochastic
Petri nets are specially suited for this aim. A compositional approach
for the translation of several UML diagrams into analyzable Petri
net models has there fore been considered in previous papers. Following
this ap proach, we will focus here in the depiction of a model case
study from the perspective of our new performance-oriented CASE tool.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/lgmc-02c.pdf},
doi={}
}

J. Merseguer, S. Bernardi, J. Campos, and S. Donatelli, “A Compositional Semantics for UML State Machines Aimed at Performance Evaluation,” in Proceedings of the 6th International Workshop on Discrete Event Systems, Zaragoza, Spain, 2002, pp. 295-302.
[Bibtex]

@INPROCEEDINGS{MBCD-wodes02,
author = {J. Merseguer and S. Bernardi and J. Campos and S. Donatelli},
title = {A Compositional Semantics for {UML} State Machines Aimed at Performance
Evaluation},
booktitle = {Proceedings of the 6th International Workshop on Discrete Event Systems},
year = {2002},
editor = {M. Silva and A. Giua and J.M. Colom},
pages = {295-302},
address = {Zaragoza, Spain},
month = {October},
publisher = {IEEE Computer Society Press},
abstract = {Unified Modeling Language (UML) is gaining widespread acceptance as
an effective way to describe the behaviour of systems. As such it
has also attracted the attention of researchers that are interested
in deriving, automatically, performance evaluation models from system's
descriptions. A required step to automatically produce a performance
model (as any executable model) is that the semantics of the description
language is formally defined. Among the various models of UML we
concentrate on States Machines and we build a semantics for them
in terms of Generalized Stochastic Petri Nets, a well established
modelling formalism for the performance evaluation of distributed
systems. The paper introduces rules that allow to derive from a description
of a system, expressed as a set of State Machines, an executable
GSPN model. The semantics is compositional since the executable GSPN
model is obtained by composing, using standard Petri Net operators,
the GSPN models of the single State Machines, and each GSPN model
is obtained by composition of submodels for State Machine basic features
such as internal and outgoing transitions, states, actions, and events.},
institution = {Departamento de Inform\'atica e Ingenier\'{\i}a de Sistemas, Universidad
de Zaragoza},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mbcd-wodes02.pdf},
doi={10.1109/WODES.2002.1167702}
}

J. P. López-Grao, J. Merseguer, and J. Campos, “On the Use of Formal Models in Software Performance Evaluation,” in Actas de las X Jornadas de Concurrencia, Jaca, Spain, 2002, pp. 367-387.
[Bibtex]

@INPROCEEDINGS{LGMC-02b,
author = {J.P. L{\'o}pez-Grao and J. Merseguer and J. Campos},
title = {On the Use of Formal Models in Software Performance Evaluation},
booktitle = {Actas de las {X} Jornadas de Concurrencia},
year = {2002},
pages = {367-387},
address = {Jaca, Spain},
month = {June},
publisher = {Universidad de Zaragoza},
abstract = {Importance of performance evaluation at first stages of the software
development life-cycle has been progressively rising. We believe
that the need for integration of formal models in the software engineering
process is a must in order to apply well-known analysis techniques
to software models. In previous papers it has been stated our proposal
of extension of UML semantics for some diagram types and a complete
method to translate them into GSPN models. Here we will focus on
activity diagrams: a new translation method for them will be presented,
while we explain their link with other UML diagrams such as statecharts
so as to amplify the expressivity at system description. Last but
not least, our CASE tool prototype will be introduced. As it will
be seen, every modeling aspect for these diagrams will be covered
and, thanks to it, the translation process will be automatically
performed.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/lgmc-02b.pdf}
}

Actas de las X Jornadas de Concurrencia, J. Campos, J. Ezpeleta, J. Júlvez, J. Merseguer, C. J. Pérez-Jiménez, and F. Tricas, Eds., Zaragoza: Ed. Kronos. ISBN 84-88502-98-2, 2002. [Publisher URL]
[Bibtex]

@Book{JC-02,
title = {Actas de las {X} Jornadas de Concurrencia},
year = {2002},
editor = {J. Campos and J. Ezpeleta and J. J{\'u}lvez and J. Merseguer and C.J. P{\'e}rez-Jim{\'e}nez and F. Tricas},
address = {Zaragoza},
publisher = {Ed. Kronos. ISBN 84-88502-98-2},
month = {June},
url = {http://webdiis.unizar.es/jjcc02/}
}

J. Campos, J. Casanovas, J. M. Colom, G. Martín, J. Martínez, A. Pont, R. Puigjaner, A. Robles, and M. R. Sancho, Informe sobre la adaptación de los estudios de TIC a la Declaración de BoloniaBarcelona, Spain: , 2002.
[Bibtex]

@UNPUBLISHED{CCCMMPPRS-02,
author = {J. Campos and J. Casanovas and J.M. Colom and G. Mart\'{i}n and J. Mart\'{i}nez and A. Pont and R. Puigjaner and A. Robles and M.R. Sancho},
title = {Informe sobre la adaptaci\'on de los estudios de {TIC} a la {D}eclaraci\'on de {B}olonia},
note = {In Spanish},
address = {Barcelona, Spain},
year = {2002},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cccmmpprs-02.pdf}
}

J. Merseguer, J. Campos, and E. Mena, “A Performance Engineering Case Study: Software Retrieval System,” Lecture Notes in Computer Science, vol. 2047, pp. 317-332, 2001.
[Bibtex]

@ARTICLE{MCM-LNCS-01,
author = {J. Merseguer and J. Campos and E. Mena},
title = {A Performance Engineering Case Study: Software Retrieval System},
journal = {Lecture Notes in Computer Science},
year = {2001},
volume = {2047},
pages = {317-332},
abstract = {This chapter presents a case study in performance engineering. The
case study consists of a Software Retrieval System based on agents.
The system is modelled in a pragmatic way using the Unified Modeling
Language and in a formal way using stochastic Petri Nets. Once the
system has been modelled, performance figures are obtained from the
formal model. Finally, some concluding remarks are obtained from
our experience in the software performance process.},
address = {Heidelberg},
booktitle = {Performance Engineering. State of the Art and Current Trends},
editor = {R. Dumke and C. Rautenstrauch and A. Schmietendorf and A. Scholz},
publisher = {Springer-Verlag},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mcm-lncs-01.pdf},
doi={10.1007/3-540-45156-0_20}
}

J. Merseguer, J. Campos, and E. Mena, “Web-Based Versus Mobile Agent-Based Software Retrieval Systems: Performance Comparison,” in Actas de las IX Jornadas de Concurrencia, Sitges, Spain, 2001, pp. 299-312.
[Bibtex]

@INPROCEEDINGS{MCM-JJCC-01,
author = {J. Merseguer and J. Campos and E. Mena},
title = {Web-Based Versus Mobile Agent-Based Software Retrieval Systems: Performance
Comparison},
booktitle = {Actas de las {IX} Jornadas de Concurrencia},
year = {2001},
pages = {299-312},
address = {Sitges, Spain},
month = {June},
publisher = {Universitat Ramon Llull},
abstract = {Nowadays, there exist web sites that allow users to retrieve and install
software in an easy way. The performance of these sites may be poor
if they are used in wireless networks; the reason is the inadequate
use of the net resources they need. If this kind of systems are designed
using mobile agent technology the previous problem might be avoided.
In this paper, we present a comparison between the performance of
a software retrieval system especially designed to be used in wireless
networks (e.g., mobile computers) and the performance of a software
retrieval system similar to the well-known Tucows.com or Download.com
web sites. In order to compare performance, we make use of a software
performance process enriched with formal techniques. The process
has as important features that it uses UML as a design notation and
it uses stochastic Petri nets as formal model. Petri nets provide
a formal semantics for the system and a performance model.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mcm-jjcc-01.pdf}
}

J. Campos, “Evaluación de Prestaciones de Sistemas Concurrentes Modelados con Redes de Petri,” in Actas de la XI Escuela de Verano de Informática de la Universidad de Castilla-La Mancha, Universidad de Castilla-La Mancha, Albacete, Spain, 2001, pp. 141-156.
[Bibtex]

@INPROCEEDINGS{Cam-EVI-01,
author = {J. Campos},
title = {Evaluaci\'on de Prestaciones de Sistemas Concurrentes Modelados con
Redes de {Petri}},
booktitle = {Actas de la {XI} Escuela de Verano de Inform\'atica de la Universidad
de Castilla-La Mancha},
year = {2001},
pages = {141-156},
address = {Universidad de Castilla-La Mancha, Albacete, Spain},
month = {July},
publisher = {Departamento de Inform\'atica},
note = {In Spanish},
abstract = {Formal methods are the most suitable way to model and analyze several
kinds of software systems. However, conventional methods are gaining
placed in Software Engineering field because they can be easily applied
in all the stages of the software life cycle. The combination of
formal and conventional methods could be an interesting approach
to describe and analyze some software aspects, as for example, the
performance of the system. In this way, we make use of a software
performance process enriched with formal techniques. The process
has as important features that it uses UML as a design notation and
it uses stochastic Petri nets as formal model. Petri nets provide
a formal semantics for the system and a performance model, while
UML supplies the framework and tools to document the system. The
process is used in this article to present a performance comparison
between software retrieval systems. Nowadays, there exist web sites
that allow users to retrieve and install software in an easy way.
The performance of these sites may be poor if they are used in wireless
networks; the reason is the inadequate use of the net resources they
need. In this article, we show that if this kind of systems are designed
using mobile agent technology the previous problem might be avoided.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cam-evi-01.pdf}
}

J. Merseguer, J. Campos, and E. Mena, “Performance Analysis of Internet Based Software Retrieval Systems Using Petri Nets,” in Proceedings of the 4th ACM International Workshop on Modeling, Analysis and Simulation of Wireless and Mobile Systems, within the 7th International Conference on Mobile Computing and Networking, Rome, Italy, 2001, pp. 47-56.
[Bibtex]

@INPROCEEDINGS{MCM-MSWiM-01,
author = {J. Merseguer and J. Campos and E. Mena},
title = {Performance Analysis of Internet Based Software Retrieval Systems
Using {Petri} Nets},
booktitle = {Proceedings of the 4th {ACM} International Workshop on Modeling,
Analysis and Simulation of Wireless and Mobile Systems, within the
7th International Conference on Mobile Computing and Networking},
year = {2001},
editor = {M. Meo and T. Dahlberg and L. Donatiello},
pages = {47-56},
address = {Rome, Italy},
month = {July},
publisher = {ACM},
abstract = {Nowadays, there exist web sites that allow users the retrieval and
installation of software in an easy way. The performance of this
task may be poor because of an inadequate use of the net resources.
If these kind of systems were designed using mobile agent technology
this problem might be avoided. In this paper, we present a comparison
between the performance of a software retrieval system designed using
mobile agents and the performance of a software retrieval system
similar to the well-known Tucows or Download.com web sites. In order
to compare performance, we make use of a software performance process
enriched with formal techniques. The process has as important features
that it uses UML as a design notation and it uses Petri nets as formal
model. Petri nets provide a formal semantic for the system and a
performance model.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mcm-mswim-01.pdf},
doi={10.1145/381591.381604}
}

J. Merseguer, J. Campos, and E. Mena, “A Pattern-Based Approach to Model Software Performance,” in Proceedings of the Second International Workshop on Software and Performance, Ottawa, Canada, 2000, pp. 137-142.
[Bibtex]

@INPROCEEDINGS{MCM-WOSP-00,
author = {J. Merseguer and J. Campos and E. Mena},
title = {A Pattern-Based Approach to Model Software Performance},
booktitle = {Proceedings of the Second International Workshop on Software and
Performance},
year = {2000},
pages = {137-142},
address = {Ottawa, Canada},
month = {September},
publisher = {ACM},
abstract = {The use of the object-oriented paradigm in the software industry is
nowadays a reality. Approximations like frameworks, components, workflows
or patterns are gaining place, sometimes to complement object-oriented
development. Like the object-oriented paradigm of these approaches
make special emphasis on the reuse of the software as a way to increase
productivity. But the performance of software systems is not as good
as desired. Thus, techniques to predict it are subject of research.
Software Performance Engineering is concerned with these problems.
Here we present an approach to reuse performance models developed
in the early stages of the software development process. The approach
has as a goal the use of formal models to predict performance.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mcm-wosp-00.pdf},
doi={10.1145/350391.350421}
}

J. Merseguer, J. Campos, and E. Mena, “Evaluating Performance on Mobile Agents Software Design,” in Actas de las VIII Jornadas de Concurrencia, Cuenca, Spain, 2000, pp. 291-307.
[Bibtex]

@INPROCEEDINGS{MCM-JJCC-00,
author = {J. Merseguer and J. Campos and E. Mena},
title = {Evaluating Performance on Mobile Agents Software Design},
booktitle = {Actas de las VIII Jornadas de Concurrencia},
year = {2000},
editor = {D. Cazorla},
pages = {291-307},
address = {Cuenca, Spain},
month = {June},
publisher = {Universidad de Castilla-la Mancha},
abstract = {Software design and implementation using mobile agents are nowadays
involved in a scepticism halo. There exist researchers who question
its utility because it could be a new technology which no new skills
but could introduce new problems. Security and performance are the
most critical aspects for this new kind of software. In this contribution
we present a formal approach to analyze performance for this class
of systems. Our approach is integrated in the early stages of the
software development process. In this way, it is possible to predict
expected behaviour without the necessity of carry out the complete
implementation phase. To show the approach, we model a software retrieval
service system in a pragmatic way, after the corresponding formal
model is obtained and analyzed in order to study performance.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mcm-jjcc-00.pdf}
}

J. Merseguer, J. Campos, and E. Mena, “Performance Evaluation for the Design of Agent-Based Systems: A Petri Net Approach,” in Proceedings of the Workshop on Software Engineering and Petri Nets, within the 21st International Conference on Application and Theory of Petri Nets, Aarhus, Denmark, 2000, pp. 1-20.
[Bibtex]

@INPROCEEDINGS{MCM-SEPN-00,
author = {J. Merseguer and J. Campos and E. Mena},
title = {Performance Evaluation for the Design of Agent-Based Systems: A {Petri}
Net Approach},
booktitle = {Proceedings of the Workshop on Software Engineering and Petri Nets,
within the 21st International Conference on Application and Theory
of Petri Nets},
year = {2000},
editor = {Mauro Pezz{\'e} and Sol M. Shatz},
pages = {1-20},
address = {Aarhus, Denmark},
month = {June},
publisher = {University of Aarhus},
abstract = {Software design and implementation using mobile agents are nowadays
involved in a scepticism halo. There exist researchers who question
its utility because it is a new technology that could provide no
new skills but it could introduce new problems. Security and performance
are the most critical aspects for this new kind of software. In this
contribution we present a formal approach to analyze performance
for this class of systems. Our approach is integrated in the early
stages of the software development process. In this way, it is possible
to predict expected behaviour without the necessity to carry out
the complete implementation phase. To show the approach, we model
a software retrieval service system in a pragmatic way, after the
corresponding formal model is obtained and analyzed in order to study
performance.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/mcm-sepn-00.pdf},
doi={}
}

J. Campos, “Petri Nets,” Departamento de Informática e Ingeniería de Sistemas, Universidad de Zaragoza, Internal Report , 2000.
[Bibtex]

@TECHREPORT{C-RR-00-00,
author = {J. Campos},
title = {{Petri} Nets},
institution = {Departamento de Inform\'atica e Ingenier\'{\i}a de Sistemas},
year = {2000},
type = {Internal Report},
address = {Universidad de Zaragoza},
month = {February},
abstract = {A brief introduction (3 pages) to the topic for an Encyclopedia.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/c-rr-00-00.pdf}
}

J. Campos, “PNPM’99-PAPM’99-NSMC’99 Tutorial: Properties and Bounds on P/T Nets,” in Tutorials of the 8th International Workshop on Petri Nets and Performance Models, 7th International Workshop on Process Algebra and Performance Modelling, and 3rd International Meeting on Numerical Solution of Markov Chains, Zaragoza, Spain, 1999.
[Bibtex]

@INPROCEEDINGS{C-Zaragoza-99,
author = {J. Campos},
title = {{PNPM'99-PAPM'99-NSMC'99 Tutorial}: Properties and Bounds on {P/T}
Nets},
booktitle = {Tutorials of the 8th International Workshop on Petri Nets and Performance
Models, 7th International Workshop on Process Algebra and Performance
Modelling, and 3rd International Meeting on Numerical Solution of
Markov Chains},
year = {1999},
address = {Zaragoza, Spain},
month = {September},
abstract = {A complementary approach to exact or approximation techniques for
the analysis of timed or stochastic Petri net models is the computation
of bounds for their performance measures. Performance bounds are
useful in the preliminary phases of the design of a system, in which
many parameters are not known accurately. Several alternatives for
those parameters should be quickly evaluated, and rejected those
that are clearly bad. Exact (and even approximate) solutions would
be computationally very expensive. Bounds become useful in these
instances since they usually require much less computation effort.
In this tutorial, net-driven techniques for the computation of bounds
for the main performance indices of timed Petri net models are considered.
Special attention is given tothe intimate relationship between qualitative
and quantitative aspects of Petri nets. In particular, the intensive
use of structure theory of net models allows to obtain very efficient
computation techniques.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/c-zaragoza-99.pdf}
}

C. J. Pérez-Jiménez and J. Campos, “On State Space Decomposition for the Numerical Analysis of Stochastic Petri Nets,” in Proceedings of the 8th International Workshop on Petri Nets and Performance Models, Zaragoza, Spain, 1999, pp. 32-41.
[Bibtex]

@INPROCEEDINGS{PJC-PNPM99,
author = {C.J. P{\'e}rez-Jim{\'e}nez and J. Campos},
title = {On State Space Decomposition for the Numerical Analysis of Stochastic
{Petri} Nets},
booktitle = {Proceedings of the 8th International Workshop on Petri Nets and Performance
Models},
year = {1999},
pages = {32-41},
address = {Zaragoza, Spain},
month = {September},
publisher = {IEEE Computer Society Press},
abstract = {Net-driven decomposition techniques are considered in this paper in
order to reduce the state explosion problem for the computation of
performance indices of stochastic Petri nets. Basically, the idea
is to represent (or partially represent) in a decomposed manner the
reachability graph of the model so it can be used for exact and/or
approximated performance analysis. In that way, the complete storing
of the graph is avoided and, for the case of approximate analysis,
the solution of the isomorphous continuous time Markov chain is substituted
by the solution of smaller components. The techniques are applied
to a couple of non-trivial models.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pjc-pnpm99.pdf},
doi={10.1109/PNPM.1999.796530}
}

J. Campos, S. Donatelli, and M. Silva, “Structured Solution of Asynchronously Communicating Stochastic Modules,” IEEE Transactions on Software Engineering, vol. 25, iss. 2, pp. 147-165, 1999.
[Bibtex]

@ARTICLE{CDS-TSE-99,
author = {J. Campos and S. Donatelli and M. Silva},
title = {Structured Solution of Asynchronously Communicating Stochastic Modules},
journal = {IEEE Transactions on Software Engineering},
year = {1999},
volume = {25},
pages = {147-165},
number = {2},
month = {March},
abstract = {Asynchronously Communicating Stochastic Modules (SAM) are Petri nets
that can be seen as a set of modules that communicate through buffers,
so they are not (yet another) Petri net subclass, but they complement
a net with a structured view. This paper considers the problem of
exploiting the compositionality of the view to generate the state
space and to find the steady-state probabilities of a stochastic
extension of SAM in a net-driven, efficient way. Essentially, we
give an expression of an auxiliary matrix, G, which is a supermatrix
of the infinitesimal generator of a SAM. G is a tensor algebra [Davio
1981] expression of matrices of the size of the components for which
it is possible to numerically solve the characteristic steady-state
solution equation pi.G = 0, without the need to explicitly compute
G. Therefore, we obtain a method that computes the steady-state solution
of a SAM without ever explicitly computing and storing its infinitesimal
generator, and therefore without computing and storing the reachability
graph of the system. Some examples of application of the technique
are presented and compared to previous approaches.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cds-tse-99.pdf},
doi={10.1109/32.761442}
}

C. J. Pérez-Jiménez and J. Campos, “On State Space Decomposition for the Numerical Analysis of Stochastic Petri Nets,” in Actas de las VII Jornadas de Concurrencia, Gandía, Spain, 1999, pp. 249-268.
[Bibtex]

@INPROCEEDINGS{PJC-JJCC99,
author = {C. J. P{\'e}rez-Jim{\'e}nez and J. Campos},
title = {On State Space Decomposition for the Numerical Analysis of Stochastic
{Petri} Nets},
booktitle = {Actas de las VII Jornadas de Concurrencia},
year = {1999},
editor = {J.M. Bernab{\'e}u and F.D. Mu{\~n}oz},
pages = {249-268},
address = {Gand{\'{\i}}a, Spain},
month = {June},
publisher = {Universidad Polit{\'e}cnica de Valencia},
abstract = {Stochastic Petri nets is a well-known formalism adequate for the design,
validation, and performance evaluation of discrete event systems,
computer systems, manufacturing systems, telecommunication networks,
and so on. In this paper, we deal with three different techniques
to decompose the state space of a general stochastic Petri net that
can be used to decrease the time and memory requirements of numerical
analysis algorithms. The presented techniques are based on the divide
and conquer principle to compute from the original model several
submodels. These submodels can be used for a functional analysis,
structural analysis and performance evaluation (exact and approximate).
In this paper we apply the techniques to approximate throughput computation.}
}

J. Campos, “Performance Bounds” in Performance Models for Discrete Event Systems with Synchronizations: Formalisms and Analysis Techniques, G. Balbo and M. Silva, Eds., Zaragoza, Spain: Editorial KRONOS, 1998, pp. 587-635.
[Bibtex]

@INCOLLECTION{C-MATCH17-98,
author = {J. Campos},
title = {Performance Bounds},
booktitle = {Performance Models for Discrete Event Systems with Synchronizations:
Formalisms and Analysis Techniques},
publisher = {Editorial KRONOS},
year = {1998},
editor = {G. Balbo and M. Silva},
chapter = {17},
pages = {587-635},
address = {Zaragoza, Spain},
month = {September},
abstract = {A complementary approach to exact or approximation techniques for
the analysis of queueing network models is the computation of bounds
for their performance measures. Performance bounds are useful in
the preliminary phases of the design of a system, in which many parameters
are not known accurately. Several alternatives for those parameters
should be quickly evaluated, and rejected those that are clearly
bad. Exact (and even approximate) solutions would be computationally
very expensive. Bounds become useful in these instances since they
usually require much less computation effort. In this chapter, we
concentrate in net-driven techniques for the computation of bounds
for the main performance indices of timed Petri net models. Previous
works on bounds computation for classical queueing networks are not
included here and the interested reader is referred to the bibliographic
remarks in Section 17.5. The presented techniques are characterized
by their interest in stressing the intimate relationship between
qualitative and quantitative aspects of Petri nets. In particular,
the intensive use of structure theory of net models allows to obtain
very efficient computation techniques. The organization of the chapter
is the following. In Section 17.1, a general approach for the computation
of upper and lower bounds for arbitrary linear functions of average
marking of places and throughput of transitions of both timed Place/Transition
nets and timed Well-Formed Coloured nets is presented. Section 17.2
includes a more intuitive approach for the computation of throughput
upper bounds, even if it is valid only for restricted Petri net subclasses.
The relation of this technique with the general approach and the
attainability of the bound for a particular subclass of nets is included.
In Section 17.3, two possible improvements of upper and lower throughput
bounds are presented using implicit places and liveness bounds of
transitions, respectively. All the bounds computed in Sections 17.1,
17.2 and 17.3 are insensitive to the timing probability distributions
since they are based only on the knowledge of the average service
times. Section 17.4 includes a brief overview of three additional
techniques for the improvement of the bounds. Since some additional
assumptions on the form of the probability distribution functions
associated to the service of transitions or on the conflict resolution
policies are done, the obtained bounds are non-insensitive. Finally,
some bibliographic remarks are included in Section 17.5.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/c-match17-98.pdf}
}

J. Campos, “Response Time Approximation for Stochastic Marked Graphs” in Performance Models for Discrete Event Systems with Synchronizations: Formalisms and Analysis Techniques, G. Balbo and M. Silva, Eds., Zaragoza, Spain: Editorial KRONOS, 1998, pp. 797-817.
[Bibtex]

@INCOLLECTION{C-MATCH23-98,
author = {J. Campos},
title = {Response Time Approximation for Stochastic Marked Graphs},
booktitle = {Performance Models for Discrete Event Systems with Synchronizations:
Formalisms and Analysis Techniques},
publisher = {Editorial KRONOS},
year = {1998},
editor = {G. Balbo and M. Silva},
chapter = {23},
pages = {797-817},
address = {Zaragoza, Spain},
month = {September},
abstract = {A general iterative technique for approximate throughput computation
of strongly connected stochastic marked graphs (SMG's) is presented
in this Chapter. We consider SMG's with time and marking independent
exponentially distributed service times associated with transitions.
The approach has two basic foundations. First, it is deeply based
on qualitative theory of MG's. More precisely, given an arbitrary
cut (subset of places producing a net partition), a structural decomposition
technique is developed that allows us to split a strongly connected
MG into two aggregated subsystems and a basic skeleton system. And
what is more important, the behaviours of the subsystems, including
steps, language of firing sequences and reachable markings, are equivalent
to the whole system behaviour (projected on the corresponding subsets
of nodes). Second, after the decomposition phase, an iterative response
time approximation method is applied for the computation of the throughput.
Experimental results on several examples generally have an error
of less than 3%. The state space is usually reduced by more than
one order of magnitude; therefore the analysis of otherwise intractable
systems is possible. The Chapter is organized as follows. In Section
23.1, some fundamental properties on MG's and implicit places are
presented. Section 23.2 includes the structural decomposition of
MG's used in the rest of the Chapter. The iterative technique for
approximate throughput computation is described in Section 23.3.
Section 23.4 includes several application examples to illustrate
the introduced technique. Finally, some bibliographic remarks are
included in Section 23.5.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/c-match23-98.pdf}
}

J. Campos, “Performance Measures and Basic Properties” in Performance Models for Discrete Event Systems with Synchronizations: Formalisms and Analysis Techniques, G. Balbo and M. Silva, Eds., Zaragoza, Spain: Editorial KRONOS, 1998, pp. 285-304.
[Bibtex]

@INCOLLECTION{C-MATCH8-98,
author = {J. Campos},
title = {Performance Measures and Basic Properties},
booktitle = {Performance Models for Discrete Event Systems with Synchronizations:
Formalisms and Analysis Techniques},
publisher = {Editorial KRONOS},
year = {1998},
editor = {G. Balbo and M. Silva},
chapter = {8},
pages = {285-304},
address = {Zaragoza, Spain},
month = {September},
abstract = {A goal of performance modelling with timed Petri nets (TPN's) is the
estimation of some quantifiable performance measures of the system
under consideration by the simulation or analysis of the model of
the system behaviour. In order to do that, responsiveness and utilization
performance measures of the system must be described in terms of
average values of operational quantities defined on the TPN model,
like the average marking of a place or the firing frequency of a
transition. In Section 8.1, the usual average performance indices
for TPN models are derived operationally from the basic observable
events that were defined in Chapter 3. Sections 8.2 and 8.3 are devoted
to exploit the operational approach for the definition of performance
measures. In Section 8.2, operational analysis techniques are used
to partially characterize the behaviour of TPN models. Classical
operational laws, like Little's law are stated in Petri net terms.
Additionally, some operational inequalities are derived that are
typical of the presence of synchronization and that have not been
considered before in the framework of queueing networks models. Section
8.3 illustrates another aspect of the deep gap, from the analytical
point of view, existing between classical monoclass product-form
queueing networks and TPN's. While in Gordon-Newell networks the
vector of visit ratios to the stations can be easily (efficiently)
computed from the routing information, in the case of bounded TPN's
the computability of such index is a quite complex problem. This
problem leads to a classification of net models attending to the
dependency of the visit ratios on the net structure and the probabilistic
routing, on the initial marking, and on the firing time of transitions.
Since few operational analysis techniques can presently be used to
compute the performance indices of interest, the classical approach
based on stochastic processes must be considered. Section 8.4 introduces
also the definition of performance parameters on the TPN model as
expected values of the random variables that characterize the behaviour
of the model, under some stochastic assumptions. As the reader surely
knows, under ergodicity conditions the average (operationally defined)
performance indices are equal to the expected (stochastically defined)
indices, thus the techniques that will be presented later on for
the computation of expected values will be useful to compute the
average performance measures of interest. Some bibliographic remarks
are summarized in Section 8.5.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/c-match8-98.pdf}
}

M. Silva and J. Campos, “Introduction to Net-Driven Decomposition Techniques” in Performance Models for Discrete Event Systems with Synchronizations: Formalisms and Analysis Techniques, G. Balbo and M. Silva, Eds., Zaragoza, Spain: Editorial KRONOS, 1998, pp. 693-718.
[Bibtex]

@INCOLLECTION{SC-MATCH20-98,
author = {M. Silva and J. Campos},
title = {Introduction to Net-Driven Decomposition Techniques},
booktitle = {Performance Models for Discrete Event Systems with Synchronizations:
Formalisms and Analysis Techniques},
publisher = {Editorial KRONOS},
year = {1998},
editor = {G. Balbo and M. Silva},
chapter = {20},
pages = {693-718},
address = {Zaragoza, Spain},
month = {September},
abstract = {As stated in previous chapters, a fundamental question in the use
of stochastic Petri net models for performance evaluation, even under
Markovian stochastic interpretation, is the so called state explosion
problem. A general approach to deal with (computational) complexity
is to use a divide and conquer strategy, what requires the definition
of a decomposition method and the subsequent composition of partial
results to get the full solution. On the other hand, the trade-off
between computational cost and accuracy of the solution leads to
the use of approximation or bounding techniques (for instance, throughput
bounds can be computed in polynomial time on the number of transitions
and places, see Chapter 17). In this context, a pragmatic compromise
to be handled by the analyzer of a system concerns the definition
of faithful models, that may be very complex to exactly analyse (what
may lead to the use of approximation or just bounding techniques),
or simplified models, for which exact analysis can be, eventually,
accomplished. Divide and conquer strategies can be used with exact,
approximate, or bounding techniques. The techniques for performance
evaluation present in the literature consider either implicit or
explicit decomposition of net models. In [7] (see Chapter 17), an
implicit decomposition into P-semiflows is used for computing throughput
bounds for arbitrary pdf of time durations. In [19] (see Chapter
12), a decomposition into disjoint modules (usually subnets generated
by P-semiflows) is defined by the analyzer or provided by model construction;
the computational technique uses directly the information provided
by the modules to compute exact global limit probability distribution
vector. In [8], a decomposition into modules (connected through buffers)
should also be provided. In this case, the modules are complemented
with an abstract view of their environment in the full model, and
the approximate solution is computed through an iterative technique
looking for a fixed point (details will be presented in Chapter 23).
In the sequel of this Chapter and in a general context, components
will refer to (eventually) complemented modules. They are just the
elements used to build the full solution. In order to get efficient
techniques, the decomposition and, eventually, complementation process
should be net-driven (i.e., derived at net level). For this, we shall
use PN's structure theory concepts and techniques (e.g., P-semiflows,
implicit places, etc.). The Chapter is organised as follows. The
main ideas behind net-driven decompositions of PN's are introduced
in Section 20.1: the conservative and consistent components (Section
20.1.1), an example of implicit search technique into conservative
components (Section 20.1.2), an explicit decomposition of nets, designating
the modules to be used (Section 20.1.3), and the complementation
of modules to get components (that include information from the environment),
using implicit places (Section 20.1.4). A taxonomy for net-driven
decomposition techniques is proposed in Section 20.2, providing a
framework for the consideration of a significant number of performance
evaluation methods. Several representative examples of techniques
present in the literature are briefly overviewed and classified according
with the classification criteria. Some concluding remarks are included
in Section 20.3.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/sc-match20-98.pdf}
}

M. Silva and J. Campos, “Performance Evaluation of DEDS with Conflicts and Synchronizations: Net-Driven Decomposition Techniques,” in Proceedings of the 4th International Workshop on Discrete Event Systems, Cagliari, Italy, 1998, pp. 398-413.
[Bibtex]

@INPROCEEDINGS{SC-wodes98,
author = {M. Silva and J. Campos},
title = {Performance Evaluation of {DEDS} with Conflicts and Synchronizations:
Net-Driven Decomposition Techniques},
booktitle = {Proceedings of the 4th International Workshop on Discrete Event Systems},
year = {1998},
pages = {398-413},
address = {Cagliari, Italy},
month = {August},
publisher = {IEE Control},
abstract = {A fundamental question in performance evaluation, even under Markovian
interpretation, is the so called state explosion problem, what arises
if no closed solution exists (e.g., a product-form). In order to
deal with computationally complex problems, divide and conquer strategies
are sometimes successful. Here we focus on the applicability of net
structure theory to the decomposition phase. A taxonomy using two
criteria allows to situate many performance evaluation techniques
in the literature. The solution or composition phase may employ techniques
as different as Kronecker algebra, response time approximation or
bottleneck analysis.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/sc-wodes98.pdf},
doi={}
}

C. J. Pérez-Jiménez and J. Campos, “A Response Time Approximation Technique for Stochastic General P/T Systems,” in Proceedings of the 2nd IMACS International Multiconference on Computational Engineering in Systems Applications (CESA’98), Hammamet, Tunisia, 1998.
[Bibtex]

@INPROCEEDINGS{PJC-98,
author = {C.J. P{\'e}rez-Jim{\'e}nez and J. Campos},
title = {A Response Time Approximation Technique for Stochastic General {P/T}
Systems},
booktitle = {Proceedings of the 2nd IMACS International Multiconference on Computational
Engineering in Systems Applications (CESA'98)},
year = {1998},
address = {Hammamet, Tunisia},
month = {April},
abstract = {Stochastic Petri nets is a well-known formalism adequate for the design,
validation, and performance evaluation of discrete event and manufacturing
systems. In this paper, we deal with steady-state throughput approximation
of complex concurrent systems modelled with stochastic Petri nets.
More precisely, we generalize to arbitrary stochastic P/T systems
a response time approximation technique that was firstly proposed
for special net subclasses. The presented technique is based on the
divide and conquer principle and it is achieved in two steps. The
first one, a net-driven decomposition of the model into several subsystems
and the second one, an iterative solution algorithm that computes
a throughput approximation of the original model transitions based
on the solution of the embedded continuous time Markov chain of the
subsystems. Experimental results on several examples generally have
an error of less than 5%, and the state space is usually reduced
by more than one order of magnitude.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pjc-98.pdf},
doi={}
}

B. Baynat and J. Campos, “PNPM’97 Tutorial: Approximate Methods Based on Net-Driven Decompositions,” in Tutorials of the 7th International Workshop on Petri Nets and Performance Models, Saint Malo, France, 1997.
[Bibtex]

@INPROCEEDINGS{BC-StMalo-97,
author = {B. Baynat and J. Campos},
title = {{PNPM'97 Tutorial}: Approximate Methods Based on Net-Driven Decompositions},
booktitle = {Tutorials of the 7th International Workshop on Petri Nets and Performance
Models},
year = {1997},
address = {Saint Malo, France},
month = {June},
abstract = {A major drawback for the practical use of stochastic Petri net models
lies in the state explosion problem originated when the exact solution
of the associated continuous time Markov chain is achieved. This
tutorial presents some ideas an examples on approximation techniques
that try to overcome the state explosion problem within a divide
and conquer strategy and with a strong exploitation of structural
(qualitative) knowledge of the underlying Petri net model for both
the decomposition and the solution phases.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/bc-stmalo-97.pdf}
}

J. Campos, S. Donatelli, and M. Silva, “Structured Solution of Stochastic DSSP Systems,” in Proceedings of the 7th International Workshop on Petri Nets and Performance Models, Saint Malo, France, 1997, pp. 91-100.
[Bibtex]

@INPROCEEDINGS{CDS-StMalo-97,
author = {J. Campos and S. Donatelli and M. Silva},
title = {Structured Solution of Stochastic {DSSP} Systems},
booktitle = {Proceedings of the 7th International Workshop on Petri Nets and Performance
Models},
year = {1997},
pages = {91-100},
address = {Saint Malo, France},
month = {June},
publisher = {IEEE Computer Society Press},
abstract = {Deterministically Synchronized Sequential Processes (DSSP) are essentially
states machines that communicate, may be in complex forms but under
some restricted patterns, through buffer places; their definition
is compositional by nature. This paper considers the problem of exploiting
this compositionality to generate the state space and to find the
steady state probabilities of a stochastic extension of DSSP in a
net-driven, efficient way. Essentially, we give an expresion of an
auxiliary matrix, G, which is a supermatrix of the infinitesimal
generator of a DSSP. G is a tensor algebra expression of matrices
of the size of the components for which it is possible to numerically
solve the characteristic equation pi.G = 0, without the need to explicitly
compute G. Therefore, we obtain a method that computes the steady
state solution of a DSSP without ever explicitly computing and storing
its infinitesimal generator, and therefore without computing and
storing the reachability graph of the system.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cds-stmalo-97.pdf},
doi={10.1109/PNPM.1997.595540}
}

C. J. Pérez-Jiménez, J. Campos, and M. Silva, “Approximate Throughput Computation of a Class of Cooperating Sequential Processes,” in Proceedings of the Rensselaer’s Fifth International Conference on Computer Integrated Manufacturing and Automation Technology (CIMAT’96), Grenoble, France, 1996, pp. 382-389.
[Bibtex]

@INPROCEEDINGS{PJCS-96b,
author = {C.J. P{\'e}rez-Jim{\'e}nez and J. Campos and M. Silva},
title = {Approximate Throughput Computation of a Class of Cooperating Sequential
Processes},
booktitle = {Proceedings of the Rensselaer's Fifth International Conference on
Computer Integrated Manufacturing and Automation Technology (CIMAT'96)},
year = {1996},
pages = {382-389},
address = {Grenoble, France},
month = {May},
abstract = {We concentrate on a family of Discrete Event Dynamic Systems (DEDS),
modelled with Petri nets and obtained from a simple modular design
principle, that include in a controlled way primitives to deal with
concurrency, decisions, synchronization, blocking, and bulk movements
of jobs. Many assembly systems with complex behaviours at the machine
level can be described with the class of DEDS under study. We present
a structure based decomposition technique and use a fixed-point search
iterative process based on response time preservation of subsystems
to approximate the throughput. An extensive battery of numerical
experiments has shown that the error is less than 3%, and that the
state space is usually reduced by more than one order of magnitude.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pjcs-96b.pdf},
doi={}
}

C. J. Pérez-Jiménez, J. Campos, and M. Silva, “On Approximate Performance Evaluation of Manufacturing Systems Modelled with Weighted T-Systems,” in Proceedings of the IMACS/IEEE-SMC Multiconference on Computational Engineering in Systems Applications (CESA’96), Lille, France, 1996, pp. 201-207.
[Bibtex]

@INPROCEEDINGS{PJCS-96c,
author = {C.J. P{\'e}rez-Jim{\'e}nez and J. Campos and M. Silva},
title = {On Approximate Performance Evaluation of Manufacturing Systems Modelled
with Weighted {T}-Systems},
booktitle = {Proceedings of the IMACS/IEEE-SMC Multiconference on Computational
Engineering in Systems Applications (CESA'96)},
year = {1996},
pages = {201-207},
address = {Lille, France},
month = {July},
abstract = {Approximate throughput computation of a class of discrete event systems
(DES) modelled with stochastic weighted T-systems is considered.
Stochastic weighted T-systems are the weighted extension of well
known stochastic marked graphs Petri net subclass and are usually
presented as a useful model to deal with bulk consumptions or productions
of resources in manufacturing systems working on a cyclic basis.
The iterative response time approximation technique that we present
is deeply based on a previous structural decomposition and aggregation
of the net model. Experimental results on several examples generally
have and error of less than 5%. The state space is usually reduced
by more than one order of magnitude; therefore, the analysis of otherwise
intractable systems is possible.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pjcs-96c.pdf},
doi={}
}

C. J. Pérez-Jiménez, J. Campos, and M. Silva, “State Machine Reduction for the Approximate Performance Evaluation of Manufacturing Systems Modelled with Cooperating Sequential Processes,” in Proceedings of the 1996 IEEE International Conference on Robotics and Automation, Minneapolis, Minnesota, USA, 1996, pp. 1159-1165.
[Bibtex]

@INPROCEEDINGS{PJCS-96a,
author = {C.J. P{\'e}rez-Jim{\'e}nez and J. Campos and M. Silva},
title = {State Machine Reduction for the Approximate Performance Evaluation
of Manufacturing Systems Modelled with Cooperating Sequential Processes},
booktitle = {Proceedings of the 1996 IEEE International Conference on Robotics
and Automation},
year = {1996},
pages = {1159-1165},
address = {Minneapolis, Minnesota, USA},
month = {April},
abstract = {We concentrate on a family of discrete event systems obtained from
a simple modular design principle that include in a controlled way
primitives to deal with concurrency, decisions, synchronization,
blocking, and bulk movements of jobs. Due to the functional complexity
of such systems, reliable throughput approximation algorithms must
be deeply supported on a structure based decomposition technique.
We present a decomposition technique and a fixed-point search iterative
process based on response time preservation of subsystems. An extensive
battery of numerical experiments has shown that the error is less
than 3%, and that the state space is usually reduced by more than
one order of magnitude.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pjcs-96a.pdf},
doi={10.1109/ROBOT.1996.506864}
}

J. Campos, Estructuras de Datos y Algoritmos, Pedro Cerbuna, 12, Zaragoza, Spain: Prensas Universitarias de Zaragoza, 1995. [Publisher URL]
[Bibtex]

@BOOK{EDA-book-95,
title = {Estructuras de Datos y Algoritmos},
publisher = {Prensas Universitarias de Zaragoza},
year = {1995},
author = {J. Campos},
series = {Colecci{\'o}n Textos Docentes},
address = {Pedro Cerbuna, 12, Zaragoza, Spain},
note = {In Spanish},
abstract = {La abstracci\'on de acciones es la base de la metodolog\'{\i}a de
dise\~no descendente por refinamientos sucesivos, \'util para la
resoluci\'on de peque\~nos problemas de tratamiento de informaci\'on.
Sin embargo, para afrontar la construcci\'on de programas en media
y gran escala es necesaria una metodolog\'{\i}a de dise\~no modular,
que permita la partici\'on del trabajo en unidades de programa que
puedan ser desarrolladas independientemente del resto. El prop\'osito
de estos apuntes es presentar los principios b\'asicos de una metodolog\'{\i}a
de dise\~no modular basada en la abstracci\'on de datos. Este material
ha sido elaborado para servir como soporte de la asignatura Estructuras
de datos y algoritmos, que se imparte en el tercer semestre de los
estudios de Ingenier\'{\i}a Inform\'atica en el Centro Polit\'ecnico
Superior de la Universidad de Zaragoza. Los alumnos que cursan dicha
asignatura han seguido previamente dos semestres de programaci\'on
en los que han debido aprender a especificar formalmente y dise\~nar
programas en peque\~na escala, utilizando tipos de datos sencillos
(como los predefinidos en un lenguaje de programaci\'on de la familia
del Pascal); los alumnos conocen t\'ecnicas de dise\~no recursivo
e iterativo, as\'{\i} como las herramientas b\'asicas para poder
medir la eficiencia de los algoritmos (atendiendo a su tiempo de
ejecuci\'on). No obstante, el material presentado puede ser \'util
tambi\'en para un segundo nivel en todos aquellos planes de estudios
en los que se incluyan dos cursos de programaci\'on de computadores.
Pueden encontrarse en las librer\'{\i}as varios trabajos (muchos
de ellos ya cl\'asicos) con t\'{\i}tulos similares o iguales a \'este.
Sin embargo, y \'esta es la raz\'on para la existencia de uno nuevo,
la aproximaci\'on al tema que se pretende desarrollar es bien diferente.
De hecho, el t\'{\i}tulo que el autor habr\'{\i}a elegido, en caso
de no haber optado por mantener el nombre de la asignatura antes
mencionada, hubiese sido m\'as bien "Tipos abstractos de datos y
algoritmos" o mejor "Introducci\'on a la programaci\'on con tipos
abstractos de datos". La diferencia estriba en el \'enfasis que se
pretende dar en las p\'aginas que siguen a la especificaci\'on formal
de los tipos (de ah\'{\i} el t\'ermino "tipos abstractos de datos")
como herramienta fundamental para el dise\~no modular de programas,
en lugar de limitarse a presentar las estructuras de datos necesarias
para representar los valores de los tipos definidos. El comentario
anterior no debe hacer pensar al lector que el material que sigue
es original del autor. Nada m\'as lejos de la realidad. \'Unicamente
nos hemos limitado a enlazar las excelentes aproximaciones existentes
en la literatura a la definici\'on y conceptos relacionados con los
tipos abstractos de datos y su especificaci\'on algebraica (v\'eanse,
por ejemplo, los dos \'ultimos cap\'{\i}tulos de la obra de Ricardo
Pe\~na titulada Dise\~no de Programas. Formalismo y Abstracci\'on)
con los trabajos m\'as cl\'asicos sobre estructuras de datos y algoritmos
de manipulaci\'on (como, por ejemplo, Estructuras de Datos y Algoritmos,
de Aho, Hopcroft y Ullman). Los apuntes est\'an estructurados en
lecciones, agrupadas en grandes temas. En el primero de ellos, titulado
"Tipos abstractos de datos", se presentan los conceptos fundamentales
sobre los tipos abstractos de datos, su especificaci\'on formal (algebraica)
y su utilizaci\'on en el dise\~no modular de programas. El segundo
tema, "Tipos de datos lineales", introduce tres de los tipos abstractos
lineales m\'as representativos y \'utiles en programaci\'on: las
pilas, las colas y las listas con acceso por posici\'on. Para cada
nuevo tipo presentado se incluyen su especificaci\'on formal, una
o varias soluciones para la representaci\'on de sus valores, la implementaci\'on
de las operaciones m\'as importantes, su coste computacional y algunos
ejemplos de aplicaci\'on. El tercer tema, titulado "\'Arboles y esquemas
algor\'{\i}tmicos", incluye los detalles sobre algunos de los tipos
de \'arboles m\'as frecuentemente utilizados, como los \'arboles
binarios, \'arboles ordenados, \'arboles de b\'usqueda, mont\'{\i}culos,
..., y ejemplos de aplicaci\'on. Adem\'as se introducen los algoritmos
de vuelta atr\'as y las heur\'{\i}sticas voraces. Los dos \'ultimos
temas, sobre "Tipos de datos funcionales" (o tablas) e "Introducci\'on
a los grafos", no se desarrollan con la misma extensi\'on que los
anteriores por razones diferentes. En el caso de las tablas, tras
las definiciones formales convenientes, se hace hincapi\'e en la
representaci\'on mediante tablas dispersas basadas en la utilizaci\'on
de una funci\'on de localizaci\'on (hashing, en ingl\'es) y en las
tablas multidimensionales representadas mediante estructuras de listas
m\'ultiples, pues otras representaciones posibles basadas en listas
lineales o \'arboles de b\'usqueda no precisan mayor explicaci\'on
tras el estudio de los temas previos. En cuanto a los grafos, los
alumnos de Ingenier\'{\i}a Inform\'atica (a quienes va dirigida preferentemente
esta obra) han cursado previamente una asignatura titulada "Matem\'atica
discreta", en la que se les ha presentado el concepto de grafo y
una buena colecci\'on de algoritmos para su manipulaci\'on. Por ello,
y atendiendo a razones de completitud, se presentan s\'olo las especificaciones
formales y varias alternativas de representaci\'on, junto a algunas
consideraciones sobre el efecto que la elecci\'on de la representaci\'on
tiene en el coste de los algoritmos de manipulaci\'on. Por \'ultimo,
un comentario sobre las notaciones empleadas y los lenguajes de programaci\'on
que pueden servir como soporte de pr\'acticas. Para la especificaci\'on
algebraica de tipos abstractos, se utiliza una sintaxis similar a
la del lenguaje OBJ, pero en espa\~nol. En cuanto a los m\'odulos,
estructuras de datos y algoritmos, se emplea una notaci\'on algor\'{\i}tmica,
tambi\'en en espa\~nol, que consiste en una extensi\'on modular de
la notaci\'on utilizada en los apuntes sobre Introducci\'on a la
programaci\'on, elaborados por Javier Mart\'{\i}nez y Javier Campos
como soporte a la asignatura de igual nombre existente en el curriculum
de Ingenier\'{\i}a Inform\'atica del CPS. En cuanto al lenguaje de
programaci\'on soporte de las pr\'acticas, el autor desaconseja la
utilizaci\'on de las extensiones modulares de Pascal (incluido el
Modula 2), pues carecen de la posibilidad de definir tipos opacos
y tipos gen\'ericos, siendo ambos mecanismos fundamentales en la
metodolog\'{\i}a desarrollada. As\'{\i}, un lenguaje apropiado resulta
ser el Ada, dotado de la posibilidad de definici\'on de tipos opacos
y tipos gen\'ericos, con una sintaxis y sem\'antica bien pensadas
y una dificultad de aprendizaje similar al Pascal, si se limita su
presentaci\'on a la parte secuencial. Otras alternativas pueden encontrarse
en lenguajes de programaci\'on orientados a objetos (como, por ejemplo,
C++), dada la cercan\'{\i}a de los conceptos de "clase" y "tipo abstracto
de dato".},
url = {http://puz.unizar.es/catalogo/detalle.php?l=467},
doi={}
}

J. Campos, J. M. Colom, H. Jungnitz, and M. Silva, “Approximate Throughput Computation of Stochastic Marked Graphs” in Quantitative Methods in Parallel Systems, F. Baccelli, A. Jean-Marie, and I. Mitrani, Eds., Springer, 1995, pp. 175-188.
[Bibtex]

@INCOLLECTION{CCHS-QMIPSbook-95,
author = {J. Campos and J.M. Colom and H. Jungnitz and M. Silva},
title = {Approximate Throughput Computation of Stochastic Marked Graphs},
booktitle = {Quantitative Methods in Parallel Systems},
publisher = {Springer},
year = {1995},
editor = {F. Baccelli and A. Jean-Marie and I. Mitrani},
series = {Esprit Basic Research Series},
pages = {175-188},
abstract = {A general iterative technique for approximate throughput computation
of stochastic strongly connected marked graphs is presented. It generalizes
a previous technique based on net decomposition through a single
input-single output cut, allowing the split of the model through
any cut. The approach has two basic foundations. First, a deep understanding
of the qualitative behaviour of marked graphs leads to a general
decomposition technique. Second, after the decomposition phase, an
iterative response time approximation method is applied for the computation
of the throughput. Experimental results on several examples generally
have an error of less than 3%. The state space is usually reduced
by more than one order of magnitude; therefore the analysis of otherwise
intractable systems is possible.},
doi={10.1007/978-3-642-79917-4_12}
}

G. Chiola, C. Anglano, J. Campos, J. M. Colom, and M. Silva, “Operational Analysis of Timed Petri Nets and Application to the Computation of Performance Bounds” in Quantitative Methods in Parallel Systems, F. Baccelli, A. Jean-Marie, and I. Mitrani, Eds., Springer, 1995, pp. 161-174.
[Bibtex]

@INCOLLECTION{CACCM-QMIPSbook-95,
author = {G. Chiola and C. Anglano and J. Campos and J.M. Colom and M. Silva},
title = {Operational Analysis of Timed {Petri} Nets and Application to the
Computation of Performance Bounds},
booktitle = {Quantitative Methods in Parallel Systems},
publisher = {Springer},
year = {1995},
editor = {F. Baccelli and A. Jean-Marie and I. Mitrani},
series = {Esprit Basic Research Series},
pages = {161-174},
abstract = {We use operational analysis techniques to partially characterize the
behaviour of timed Petri nets under very weak assumptions on their
timing semantics. New operational inequalities are derived that are
typical of the presence of synchronization and that were therefore
not considered in queueing network models. We show an interesting
application of the operational laws to the statement and the efficient
solution of problems related to the estimation of performance bounds
insensitive to the timing probability distributions. The results
obtained generalize and improve in a clear setting results that were
derived in the last few years for several different subclasses of
timed Petri nets. In particular the extension to Well-Formed Coloured
nets appears straightforward and allows an efficient exploitation
of models symmetries.},
doi={10.1007/978-3-642-79917-4_11}
}

E. Teruel, M. Silva, J. M. Colom, and J. Campos, “Functional and Performance Analysis of Cooperating Sequential Processes” in Quantitative Methods in Parallel Systems, F. Baccelli, A. Jean-Marie, and I. Mitrani, Eds., Springer, 1995, pp. 52-65.
[Bibtex]

@INCOLLECTION{TSCC-QMIPSbook-95,
author = {E. Teruel and M. Silva and J.M. Colom and J. Campos},
title = {Functional and Performance Analysis of Cooperating Sequential Processes},
booktitle = {Quantitative Methods in Parallel Systems},
publisher = {Springer},
year = {1995},
editor = {F. Baccelli and A. Jean-Marie and I. Mitrani},
series = {Esprit Basic Research Series},
pages = {52-65},
abstract = {This paper presents some results concerning the functional and performance
analysis of sequential proceses connected through buffers using structural
analysis techniques, mainly linear algebraic ones. From the functional
point of view the following properties are considered: boundedness,
deadlock-freeness, liveness and the existence of home states. From
the performance point of view the considered properties are marking
ergodicity, computation of visit ratios and computation of insensitive
throughput bounds.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/tscc-qmipsbook-95.pdf},
doi={10.1007/978-3-642-79917-4_4}
}

C. J. Pérez-Jiménez, J. Campos, and M. Silva, “On Approximate Throughput Computation of Deterministic Systems of Sequential Processes,” in Actas de las IV Jornadas de Concurrencia, El Escorial, Spain, 1995, pp. 156-171.
[Bibtex]

@INPROCEEDINGS{PJCS-95,
author = {C.J. P{\'e}rez-Jim{\'e}nez and J. Campos and M. Silva},
title = {On Approximate Throughput Computation of Deterministic Systems of
Sequential Processes},
booktitle = {Actas de las IV Jornadas de Concurrencia},
year = {1995},
pages = {156-171},
address = {El Escorial, Spain},
month = {June},
publisher = {Universidad Complutense de Madrid},
abstract = {We concentrate on a family of discrete event systems obtained from
a simple modular design principle that include in a controlled way
primitives to deal with concurrency, decisions, synchronization,
blocking, and bulk movements of jobs. Due to the functional complexity
of such systems, reliable throughput approximation algorithms must
be deeply supported on a structure based decomposition technique.
We present two complementary decomposition techniques and a fixed-point
search iterative process based on response time preservation of subsystems.
An extensive battery of numerical experiments has shown that the
error is less than 3%, and that the state space is usually reduced
by more than one order of magnitude.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/pjcs-95.pdf}
}

M. Silva and J. Campos, “Structural Performance Analysis of Stochastic Petri Nets,” in Proceedings of the IEEE International Computer Performance and Dependability Symposium, Erlangen, Germany, 1995, pp. 61-70.
[Bibtex]

@INPROCEEDINGS{SC-Erlangen-95,
author = {M. Silva and J. Campos},
title = {Structural Performance Analysis of Stochastic {Petri} Nets},
booktitle = {Proceedings of the IEEE International Computer Performance and Dependability
Symposium},
year = {1995},
pages = {61-70},
address = {Erlangen, Germany},
month = {April},
publisher = {IEEE-Computer Society Press},
note = {Invited paper},
abstract = {Structure performance analysis theory and techniques is an essay to
avoid the computational complexity problem associated to Markovian
and discrete event simulation techniques. Even if a finished conceptual
and technical framework is not yet available, important benefits
have been obtained not only from performance but also from correctness
analysis point of view. In this survey we overview some of the achievements
developed by the authors and collaborators towards a structure theory
for performance evaluation of net based models. Concepts and techniques
for the computation of performance bounds and approximate and exact
evaluation are described in a semi-formal/illustrative way through
a selected collection of examples.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/sc-erlangen-95.pdf},
doi={10.1109/IPDS.1995.395816}
}

F. Baccelli, G. Balbo, R. J. Boucherie, J. Campos, and G. Chiola, “Annotated Bibliography on Stochastic Petri Nets” in Performance Evaluation of Parallel and Distributed Systems: Solution Methods, O. J. Boxma and G. M. Koole, Eds., Amsterdam: Centrum voor Wiskunde en Informatica, 1994, vol. 105, pp. 25-44.
[Bibtex]

@INCOLLECTION{BBBCC-QMIPS-94,
author = {F. Baccelli and G. Balbo and R.J. Boucherie and J. Campos and G.
Chiola},
title = {Annotated Bibliography on Stochastic {Petri} Nets},
booktitle = {Performance Evaluation of Parallel and Distributed Systems: Solution
Methods},
publisher = {Centrum voor Wiskunde en Informatica},
year = {1994},
editor = {O.J. Boxma and G.M. Koole},
volume = {105},
series = {Tract},
pages = {25-44},
address = {Amsterdam},
abstract = {An annotated bibliography on stochastic Petri nets is given.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/bbbcc-qmips-94.pdf},
doi={}
}

J. Campos, J. M. Colom, H. Jungnitz, and M. Silva, “A General Iterative Technique for Approximate Throughput Computation of Stochastic Marked Graphs” in Performance Evaluation of Parallel and Distributed Systems: Solution Methods, O. J. Boxma and G. M. Koole, Eds., Amsterdam: Centrum voor Wiskunde en Informatica, 1994, vol. 106, pp. 265-283.
[Bibtex]

@INCOLLECTION{CCJS-QMIPS-94,
author = {J. Campos and J.M. Colom and H. Jungnitz and M. Silva},
title = {A General Iterative Technique for Approximate Throughput Computation
of Stochastic Marked Graphs},
booktitle = {Performance Evaluation of Parallel and Distributed Systems: Solution
Methods},
publisher = {Centrum voor Wiskunde en Informatica},
year = {1994},
editor = {O.J. Boxma and G.M. Koole},
volume = {106},
series = {Tract},
pages = {265-283},
address = {Amsterdam},
abstract = {A general iterative technique for approximate throughput computation
of stochastic strongly connected marked graphs is presented. It generalizes
a previous technique based on net decomposition through a single
input-single output cut, allowing the split of the model through
any cut. The approach has two basic foundations. First, a deep understanding
of the qualitative behaviour of marked graphs leads to a general
decomposition technique. Second, after the decomposition phase, an
iterative response time approximation method is applied for the computation
of the throughput. Experimental results on several examples generally
have an error of less than 3%. The state space is usually reduced
by more than one order of magnitude; therefore the analysis of otherwise
intractable systems is possible.},
doi={}
}

J. Campos, J. M. Colom, M. Silva, and E. Teruel, “Functional and Performance Analysis of Cooperating Sequential Processes” in Performance Evaluation of Parallel and Distributed Systems: Solution Methods, O. J. Boxma and G. M. Koole, Eds., Amsterdam: Centrum voor Wiskunde en Informatica, 1994, vol. 106, pp. 233-251.
[Bibtex]

@INCOLLECTION{CCST-QMIPS-94,
author = {J. Campos and J.M. Colom and M. Silva and E. Teruel},
title = {Functional and Performance Analysis of Cooperating Sequential Processes},
booktitle = {Performance Evaluation of Parallel and Distributed Systems: Solution
Methods},
publisher = {Centrum voor Wiskunde en Informatica},
year = {1994},
editor = {O.J. Boxma and G.M. Koole},
volume = {106},
series = {Tract},
pages = {233-251},
address = {Amsterdam},
abstract = {This paper presents some results concerning the functional and performance
analysis of sequential proceses connected through buffers using structural
analysis techniques, mainly linear algebraic ones. From the functional
point of view the following properties are considered: boundedness,
deadlock-freeness, liveness and the existence of home states. From
the performance point of view the considered properties are marking
ergodicity, computation of visit ratios and computation of insensitive
throughput bounds.},
doi={}
}

G. Chiola, C. Anglano, J. Campos, J. M. Colom, and M. Silva, “Operational Analysis of Timed Petri Nets and Application to the Computation of Performance Bounds” in Performance Evaluation of Parallel and Distributed Systems: Solution Methods, O. J. Boxma and G. M. Koole, Eds., Amsterdam: Centrum voor Wiskunde en Informatica, 1994, vol. 106, pp. 197-213.
[Bibtex]

@INCOLLECTION{CACCS-QMIPS-94,
author = {G. Chiola and C. Anglano and J. Campos and J.M. Colom and M. Silva},
title = {Operational Analysis of Timed {Petri} Nets and Application to the
Computation of Performance Bounds},
booktitle = {Performance Evaluation of Parallel and Distributed Systems: Solution
Methods},
publisher = {Centrum voor Wiskunde en Informatica},
year = {1994},
editor = {O.J. Boxma and G.M. Koole},
volume = {106},
series = {Tract},
pages = {197-213},
address = {Amsterdam},
abstract = {We use operational analysis techniques to partially characterize the
behaviour of timed Petri nets under very weak assumptions on their
timing semantics. New operational inequalities are derived that are
typical of the presence of synchronization and that were therefore
not considered in queueing network models. We show an interesting
application of the operational laws to the statement and the efficient
solution of problems related to the estimation of performance bounds
insensitive to the timing probability distributions. The results
obtained generalize and improve in a clear setting results that were
derived in the last few years for several different subclasses of
timed Petri nets. In particular the extension to Well-Formed Coloured
nets appears straightforward and allows an efficient exploitation
of models symmetries.},
doi={}
}

E. Teruel, M. Silva, J. M. Colom, and J. Campos, “Functional and Performance Analysis of Cooperating Sequential Processes,” Lecture Notes in Control and Information Sciences, vol. 199, pp. 169-175, 1994.
[Bibtex]

@ARTICLE{TSCC-LNCIS-94,
author = {E. Teruel and M. Silva and J.M. Colom and J. Campos},
title = {Functional and Performance Analysis of Cooperating Sequential Processes},
journal = {Lecture Notes in Control and Information Sciences},
year = {1994},
volume = {199},
pages = {169-175},
abstract = {A class of Petri nets suitable for modelling sequential processes
cooperating by means of message passing is presented. Some functional
(boundedness, liveness, home states) and performance (ergodicity,
computation of visit ratios and throughput bounds) aspects are considered
from a structure theory perspective.},
address = {London},
booktitle = {Analysis and Optimization of Systems: Discrete Event Systems},
editor = {G. Cohen and J.P. Quadrat},
publisher = {Springer-Verlag},
doi={10.1007/BFb0033545}
}

J. Campos, J. M. Colom, H. Jungnitz, and M. Silva, “Approximate Throughput Computation of Stochastic Marked Graphs,” IEEE Transactions on Software Engineering, vol. 20, iss. 7, pp. 526-535, 1994.
[Bibtex]

@ARTICLE{CCJS-TSE-94,
author = {J. Campos and J.M. Colom and H. Jungnitz and M. Silva},
title = {Approximate Throughput Computation of Stochastic Marked Graphs},
journal = {IEEE Transactions on Software Engineering},
year = {1994},
volume = {20},
pages = {526-535},
number = {7},
month = {July},
abstract = {A general iterative technique for approximate throughput computation
of stochastic strongly connected marked graphs is presented. It generalizes
a previous technique based on net decomposition through a single
input-single output cut, allowing the split of the model through
any cut. The approach has two basic foundations. First, a deep understanding
of the qualitative behaviour of marked graphs leads to a general
decomposition technique. Second, after the decomposition phase, an
iterative response time approximation method is applied for the computation
of the throughput. Experimental results on several examples generally
have an error of less than 3%. The state space is usually reduced
by more than one order of magnitude; therefore the analysis of otherwise
intractable systems is possible.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/ccjs-tse-94.pdf},
doi={10.1109/32.297941}
}

G. Balbo, M. Silva, G. Chiola, J. Campos, and others, “The Timed (Coloured) Petri Net Formalism: Position Paper” in Workshop on Formalisms, Principles, and State-of-the-Art, Erlangen, Germany: Arbeitsberichte des Instituts für Mathematische Maschinen und Datenverarbeitung (Informatik), 1993, vol. 14, pp. 3-60.
[Bibtex]

@INCOLLECTION{State-of-the-art-93,
author = {G. Balbo and M. Silva and G. Chiola and J. Campos and others},
title = {The Timed (Coloured) {Petri} Net Formalism: Position Paper},
booktitle = {Workshop on Formalisms, Principles, and State-of-the-Art},
publisher = {Arbeitsberichte des Instituts f{\"u}r Mathematische Maschinen und
Datenverarbeitung (Informatik)},
year = {1993},
volume = {14},
series = {Band 26},
pages = {3-60},
address = {Erlangen, Germany},
abstract = {This paper presents the point of view of the groups of the universities
of Torino and Zaragoza on the timed Petri net formalism. Coloured
and non coloured models are covered at the same time, the latter
making sense in case of systems without symmetries. We argue that
Petri net formalisms allow more freedom than other established formalisms
in the choices regarding the trade off between structural model complexity
and interpretation of the graph. Some considerations are made on
coloured Petri nets that could suggest them as a superior modelling
formalism. The main comparison term that we selected are BCMP type
queueing networks.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/state-of-the-art-93.pdf},
doi={}
}

J. Campos, B. F. Plo, and M. San Miguel, “Boundedness on Stochastic Petri Nets,” Revista Matemática de la Universidad Complutense de Madrid, vol. 6, iss. 1, pp. 123-136, 1993.
[Bibtex]

@ARTICLE{CPSM-RMUCM-93,
author = {J. Campos and B.F. Plo and San Miguel, M.},
title = {Boundedness on Stochastic {Petri} Nets},
journal = {Revista Matem{\'a}tica de la Universidad Complutense de Madrid},
year = {1993},
volume = {6},
pages = {123-136},
number = {1},
abstract = {Stochastic Petri nets generalize the notion of queueing systems and
are a useful model in performance evaluation of parallel and distributed
systems. We give necessary and sufficient conditions for the boundedness
of a stochastic process related to these nets.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cpsm-rmucm-93.pdf},
doi={}
}

G. Chiola, J. Campos, J. M. Colom, and M. Silva, “Operational Analysis of Timed Petri Nets,” in Proceedings of the 16th International Symposium on Computer Performance Modelling, Measurement and Evaluation (Performance’93), Roma, Italy, 1993.
[Bibtex]

@INPROCEEDINGS{CCCS-Roma-93,
author = {G. Chiola and J. Campos and J.M. Colom and M. Silva},
title = {Operational Analysis of Timed {Petri} Nets},
booktitle = {Proceedings of the 16th International Symposium on Computer Performance
Modelling, Measurement and Evaluation (Performance'93)},
year = {1993},
address = {Roma, Italy},
month = {September},
abstract = {Operational analysis is a conceptually very simple way of deriving
mathematical equations relating measurable quantities in queueing
systems [DB 78]. In [DC 92] the reader can find some nice examples
of how the application of operational analysis techniques can help
in explaining and proving fundamental results in queueing network
analysis. Here we apply operational analysis techniques to derive
linear equations and inequalities relating interesting performance
measures in timed Petri net models. The main conceptual difference
between queueing and Petri net models is the presence of a synchronization
primitive in the latter. New operational inequalities are derived
for synchronization elements that have no counterpart in operational
laws for queueing networks. In addition to the mathematical interest
of these derivations, the results can be immediately used for the
computation of performance bounds based on linear programming techniques.},
doi={}
}

J. Campos, J. M. Colom, H. Jungnitz, and M. Silva, “A General Iterative Technique for Approximate Throughput Computation of Stochastic Marked Graphs,” in Proceedings of the 5th International Workshop on Petri Nets and Performance Models, Toulouse, France, 1993, pp. 138-147.
[Bibtex]

@INPROCEEDINGS{CCJS-Toulouse-93,
author = {J. Campos and J.M. Colom and H. Jungnitz and M. Silva},
title = {A General Iterative Technique for Approximate Throughput Computation
of Stochastic Marked Graphs},
booktitle = {Proceedings of the 5th International Workshop on Petri Nets and Performance
Models},
year = {1993},
pages = {138-147},
address = {Toulouse, France},
month = {October},
publisher = {IEEE-Computer Society Press},
abstract = {A general iterative technique for approximate throughput computation
of stochastic strongly connected marked graphs is presented. It generalizes
a previous technique based on net decomposition through a single
input-single output cut, allowing the split of the model through
any cut. The approach has two basic foundations. First, a deep understanding
of the qualitative behaviour of marked graphs leads to a general
decomposition technique. Second, after the decomposition phase, an
iterative response time approximation method is applied for the computation
of the throughput. Experimental results on several examples generally
have an error of less than 3%. The state space is usually reduced
by more than one order of magnitude; therefore the analysis of otherwise
intractable systems is possible.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/ccjs-toulouse-93.pdf},
doi={10.1109/PNPM.1993.393427}
}

G. Chiola, C. Anglano, J. Campos, J. M. Colom, and M. Silva, “Operational Analysis of Timed Petri Nets and Application to the Computation of Performance Bounds,” in Proceedings of the 5th International Workshop on Petri Nets and Performance Models, Toulouse, France, 1993, pp. 128-137.
[Bibtex]

@INPROCEEDINGS{CACCS-Toulouse-93,
author = {G. Chiola and C. Anglano and J. Campos and J.M. Colom and M. Silva},
title = {Operational Analysis of Timed {Petri} Nets and Application to the
Computation of Performance Bounds},
booktitle = {Proceedings of the 5th International Workshop on Petri Nets and Performance
Models},
year = {1993},
pages = {128-137},
address = {Toulouse, France},
month = {October},
publisher = {IEEE-Computer Society Press},
abstract = {We use operational analysis techniques to partially characterize the
behaviour of timed Petri nets under very weak assumptions on their
timing semantics. New operational inequalities are derived that are
typical of the presence of synchronization and that were therefore
not considered in queueing network models. We show an interesting
application of the operational laws to the statement and the efficient
solution of problems related to the estimation of performance bounds
insensitive to the timing probability distributions. The results
obtained generalize and improve in a clear setting results that were
derived in the last few years for several different subclasses of
timed Petri nets. In particular the extension to Well-Formed Coloured
nets appears straightforward and allows an efficient exploitation
of models symmetries.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/caccs-toulouse-93.pdf},
doi={10.1109/PNPM.1993.393428}
}

A. Ramírez, J. Campos, and M. Silva, “On Optimal Scheduling in DEDS,” in Proceedings of the 1993 IEEE International Conference on Robotics and Automation, Atlanta, USA, 1993, pp. 821-826.
[Bibtex]

@INPROCEEDINGS{RCS-Atlanta-93,
author = {A. Ram{\'{\i}}rez and J. Campos and M. Silva},
title = {On Optimal Scheduling in {DEDS}},
booktitle = {Proceedings of the 1993 IEEE International Conference on Robotics
and Automation},
year = {1993},
pages = {821-826},
address = {Atlanta, USA},
month = {May},
abstract = {In this paper we present the Local Optimality (LO) property for Discrete
Event Dynamic Systems modeled using Petri Nets (PN's). If a system
is divided into independent subsystems and if the optimal behaviour
of these subsystems guarantees the optimal behaviour of whole system,
then this system possesses the LO property. The main advantage of
this approach is that we can find an optimal schedule for this class
of systems in less time, because we are determining the optimal behaviour
of small problems. A characterization of systems exhibiting the LO
property is given, as well as one procedure to divide them into subsystems.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/rcs-atlanta-93.pdf},
doi={10.1109/ROBOT.1993.292246}
}

J. Campos and M. Silva, “Embedded Product-Form Queueing Networks and the Improvement of Performance Bounds for Petri Net Systems,” Performance Evaluation, vol. 18, iss. 1, pp. 3-19, 1993.
[Bibtex]

@ARTICLE{CS-PE-93,
author = {J. Campos and M. Silva},
title = {Embedded Product-Form Queueing Networks and the Improvement of Performance
Bounds for {Petri} Net Systems},
journal = {Performance Evaluation},
year = {1993},
volume = {18},
pages = {3-19},
number = {1},
month = {July},
abstract = {This paper addresses the computation of upper bounds for the steady-state
throughput of stochastic Petri net systems with immediate and generally
distributed timed transitions. It is achieved through the use of
a kind of decomposition of the whole net system. Results are obtained
deeply bridging stochastic Petri net theory to untimed Petri net
and queueing network theories. Previous results are improved by considering
some embedded product-form queueing networks (generated by the support
of some left annullers of the incidence matrix of the net). The obtained
results for the case of live and bounded free choice systems are
of special interest. In this case, the subnets generated by the minimal
left annullers of the incidence matrix always have a topology of
product-form closed monoclass queueing networks.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cs-pe-93.pdf},
doi={10.1016/0166-5316(93)90024-O}
}

M. Silva and J. Campos, “Performance Models Based on Petri Nets,” in Proceedings of the IMACS/IFAC Second International Symposium on Mathematical and Intelligent Models in System Simulation, 1993, p. xiv-xxi.
[Bibtex]

@INPROCEEDINGS{SC-Brussels-93,
author = {M. Silva and J. Campos},
title = {Performance Models Based on {Petri} Nets},
booktitle = {Proceedings of the IMACS/IFAC Second International Symposium on Mathematical
and Intelligent Models in System Simulation},
year = {1993},
pages = {xiv-xxi},
month = {April},
publisher = {Brussels, Belgium},
note = {Invited paper},
abstract = {Petri Nets (PNs) is a well suited formalism to model and analyze parallel
and distributed discrete event dynamic systems. Provided with adequate
timed interpretation, PNs allow to build performance models in which
true concurrence can be described together with synchronization and
sharing phenomena. This survey paper gives a fast overview of some
major topics related to net performance models, obtained through
stochastically timed interpretation of PNs. Analysis of net models,
pointing out the importance of the logical and performance perspectives,
and some relations between queueing networks and PN models are briefly
considered.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/sc-brussels-93.pdf},
doi={}
}

J. Campos, J. M. Colom, and M. Silva, “Improving Throughput Upper Bounds for Net Based Models of Manufacturing Systems” in Robotics and Flexible Manufacturing Systems, J. C. Gentina and S. G. Tzafestas, Eds., Amsterdam, The Netherlands: Elsevier Science Publishers B.V. (North-Holland), 1992, pp. 281-294.
[Bibtex]

@INCOLLECTION{CCS-RFMS-92,
author = {J. Campos and J.M. Colom and M. Silva},
title = {Improving Throughput Upper Bounds for Net Based Models of Manufacturing
Systems},
booktitle = {Robotics and Flexible Manufacturing Systems},
publisher = {Elsevier Science Publishers B.V. (North-Holland)},
year = {1992},
editor = {J.C. Gentina and S.G. Tzafestas},
pages = {281-294},
address = {Amsterdam, The Netherlands},
abstract = {This paper addresses the improvement of throughput upper bounds for
live and bounded stochastic Petri nets, presented by the authors
in previous works. The introduction of a greater amount of structural
information, traps and implicit places, allows to improve the bounds
using linear programming problems defined on the net structure, on
the routing probabilities, and on the mean service time of transitions.
The obtained bounds can be applied for the analysis of manufacturing
systems modelled by means of stochastic Petri nets. An example is
presented and evaluated using the introduced techniques.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/ccs-rfms-92.pdf},
doi={}
}

J. Campos and M. Silva, “Structural Techniques and Performance Bounds of Stochastic Petri Net Models,” Lecture Notes in Computer Science, vol. 609, pp. 352-391, 1992.
[Bibtex]

@ARTICLE{CS-LNCS-92,
author = {J. Campos and M. Silva},
title = {Structural Techniques and Performance Bounds of Stochastic {Petri}
Net Models},
journal = {Lecture Notes in Computer Science},
year = {1992},
volume = {609},
pages = {352-391},
abstract = {In this paper we overview some recent results obtained by the authors
and collaborators on the performance bounds analysis of some stochastic
Petri net systems. The mathematical model can be seen either as a
result of the addition of a particular random timing interpretation
to an "autonomous'' Petri net or as a generalization of classical
queueing networks with the addendum of a general synchronization
primitive. It constitutes an adequate tool for both the validation
of logical properties and the evaluation of performance measures
of concurrent and distributed systems. Qualitative and quantitative
understandings of Petri net models are stressed here making special
emphasis on structural techniques for the analysis of logical and
performance properties. Important aspects from the performance point
of view, such as relative throughput of stations (transitions), and
number of servers present at them, are related to Petri net concepts
like P- or T-semiflows or liveness bounds of transitions. For the
particularly interesting case of Markovian Petri net systems, some
improvements of the bounds can be achieved. Marked graphs and free
choice are net subclasses for which the obtained results have special
quality, therefore an additional attention is focussed on them.},
address = {Berlin},
booktitle = {Advances in Petri Nets 1992},
editor = {G. Rozenberg},
publisher = {Springer-Verlag},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cs-lncs-92.pdf},
doi={10.1007/3-540-55610-9_178}
}

M. Silva, J. M. Colom, and J. Campos, “Linear Algebraic Techniques for the Analysis of Petri Nets” in Recent Advances in Mathematical Theory of Systems, Control, Networks, and Signal Processing II, Tokyo, Japan: Mita Press, 1992, pp. 35-42.
[Bibtex]

@INCOLLECTION{SCC-Mita-91,
author = {M. Silva and J.M. Colom and J. Campos},
title = {Linear Algebraic Techniques for the Analysis of {Petri} Nets},
booktitle = {Recent Advances in Mathematical Theory of Systems, Control, Networks,
and Signal Processing II},
publisher = {Mita Press},
year = {1992},
pages = {35-42},
address = {Tokyo, Japan},
abstract = {One of the indigenous techniques for the analysis of Petri Net system
models is based on its non-negative state equation, bridging convex
goemetry and linear programming theories to the theory of Petri Nets.
This invited survey briefly overviews some recent developments in
the use of linear algebraic techniques for the qualitative (i.e.,
logical) and quantitative (i.e., performance) analysis of Petri Net
system models, dealing with properties like deadlock-freeness, structural
liveness or throughput bounds.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/scc-mita-91.pdf},
doi={}
}

J. Campos, G. Chiola, J. M. Colom, and M. Silva, “Properties and Performance Bounds for Timed Marked Graphs,” IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, vol. 39, iss. 5, pp. 386-401, 1992.
[Bibtex]

@ARTICLE{CCCS-CAS-92,
author = {J. Campos and G. Chiola and J.M. Colom and M. Silva},
title = {Properties and Performance Bounds for Timed Marked Graphs},
journal = {IEEE Transactions on Circuits and Systems I: Fundamental Theory and
Applications},
year = {1992},
volume = {39},
pages = {386-401},
number = {5},
month = {May},
abstract = {A class of synchronized queueing networks with deterministic routing
is identified to be equivalent to a subclass of timed Petri nets
called marked graphs. First some structural and behavioral properties
of marked graphs are recalled and used to show interesting properties
of this class of performance models. In particular, ergodicity is
derived from boundedness and liveness of the underlying Petri net
representation, which can be efficiently computed in polynomial time
on the net structure. In case of unbounded (i.e., non-strongly-connected)
marked graphs, ergodicity is computed as a function of the average
transition firing delays. Then the problem of computing both upper
and lower bounds for the steady-state performance of timed and stochastic
marked graphs is studied. In particular, linear programming problems
defined on the incidence matrix of the underlying Petri nets are
used to compute tight (i.e., attainable) bounds for the throughput
of transitions for marked graphs with deterministic or stochastic
time associated with transitions. These bounds depend on the initial
marking and the mean values of the delays but not on the probability
distribution functions (thus including both the deterministic and
the stochastic cases). The benefits of interleaving qualitative and
quantitative analysis of marked graph models are shown.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cccs-cas-92.pdf},
doi={10.1109/81.139289}
}

J. Campos, “Performance Analysis of Live and Bounded Free Choice Systems” in Design Methods Based on Nets, E. Best and J. Esparza, Eds., Sankt Augustin, Germany: , 1991, pp. 38-48.
[Bibtex]

@INCOLLECTION{C-DEMON-91,
author = {J. Campos},
title = {Performance Analysis of Live and Bounded Free Choice Systems},
booktitle = {Design Methods Based on Nets},
year = {1991},
editor = {E. Best and J. Esparza},
series = {GMD-Studien Nr. 198},
pages = {38-48},
address = {Sankt Augustin, Germany},
month = {September},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/c-demon-91.pdf},
doi={}
}

J. Campos, J. M. Colom, and M. Silva, “Improving Throughput Upper Bounds for Net Based Models,” in Proceedings of the IMACS-IFAC International Symposium on Modeling and Control of Technological Systems, Lille, France, 1991, pp. 573-582.
[Bibtex]

@INPROCEEDINGS{CCS-Lille-91,
author = {J. Campos and J.M. Colom and M. Silva},
title = {Improving Throughput Upper Bounds for Net Based Models},
booktitle = {Proceedings of the IMACS-IFAC International Symposium on Modeling
and Control of Technological Systems},
year = {1991},
pages = {573-582},
address = {Lille, France},
month = {May},
abstract = {This paper addresses the improvement of throughput upper bounds for
live and bounded stochastic Petri nets, presented by the authors
in previous works. The introduction of a greater amount of structural
information, traps and implicit places, allows to improve the bounds
using linear programming problems defined on the net structure, on
the routing probabilities, and on the mean service time of transitions.
The obtained bounds can be applied for the analysis of manufacturing
systems modelled by means of stochastic Petri nets. An example is
presented and evaluated using the introduced techniques.},
doi={}
}

J. Campos and J. M. Colom, “A Reachable Throughput Upper Bound for Live and Safe Free Choice Nets,” in Proceedings of the Twelfth International Conference on Application and Theory of Petri Nets, Gjern, Denmark, 1991, pp. 237-256.
[Bibtex]

@INPROCEEDINGS{CC-Gjern-91,
author = {J. Campos and J.M. Colom},
title = {A Reachable Throughput Upper Bound for Live and Safe Free Choice
Nets},
booktitle = {Proceedings of the Twelfth International Conference on Application
and Theory of Petri Nets},
year = {1991},
pages = {237-256},
address = {Gjern, Denmark},
month = {June},
organization = {EATCS},
publisher = {IBM Deutschland},
abstract = {This paper addresses the computation of upper bounds for the throughput
of transitions of live and safe deterministically or stochastically
timed free choice nets. The obtained results are extensions of the
marked graph case, presented by the authors in previous works. Polynomial
complexity algorithms are derived using linear programming techniques.
The obtained values are tight in the sense that, with the only knowledge
of the net topology, the mean service times of transitions, and the
routing rates at conflicts, is not possible to improve the bounds.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cc-gjern-91.pdf},
doi={}
}

M. Silva, J. M. Colom, and J. Campos, “Linear Algebraic Techniques for the Analysis of Petri Nets,” in Proceedings of the International Symposium on the Mathematical Theory of Networks and Systems, Kobe, Japan, 1991, pp. 413-415.
[Bibtex]

@INPROCEEDINGS{SCC-Kobe-91,
author = {M. Silva and J.M. Colom and J. Campos},
title = {Linear Algebraic Techniques for the Analysis of {Petri} Nets},
booktitle = {Proceedings of the International Symposium on the Mathematical Theory
of Networks and Systems},
year = {1991},
pages = {413-415},
address = {Kobe, Japan},
month = {June},
abstract = {One of the indigenous techniques for the analysis of Petri Net system
models is based on its non-negative state equation, bridging convex
goemetry and linear programming theories to the theory of Petri Nets.
This invited survey briefly overviews some recent developments in
the use of linear algebraic techniques for the qualitative (i.e.,
logical) and quantitative (i.e., performance) analysis of Petri Net
system models, dealing with properties like deadlock-freeness, structural
liveness or throughput bounds.},
doi={}
}

J. Campos, G. Chiola, and M. Silva, “Ergodicity and Throughput Bounds of Petri Nets with Unique Consistent Firing Count Vector,” IEEE Transactions on Software Engineering, vol. 17, iss. 2, pp. 117-125, 1991.
[Bibtex]

@ARTICLE{CCS-TSE-91,
author = {J. Campos and G. Chiola and M. Silva},
title = {Ergodicity and Throughput Bounds of {Petri} Nets with Unique Consistent
Firing Count Vector},
journal = {IEEE Transactions on Software Engineering},
year = {1991},
volume = {17},
pages = {117-125},
number = {2},
month = {February},
abstract = {This paper addresses ergodicity and throughput bounds characterizations
for a subclass of timed and stochastic Petri nets, interleaving qualitative
and quantitative theories. The considered nets represent an extension
of the well known subclass of marked graphs, defined as having a
unique consistent firing count vector, independently of the stochastic
interpretation of the net model. In particular, persistent and mono-T-semiflow
nets subclasses are considered. Upper and lower throughput bounds
are computed using linear programming problems defined on the incidence
matrix of the underlying net. The bounds proposed here depend on
the initial marking and the mean values of the delays but not on
the probability distributions (thus including both the deterministic
and the stochastic cases). From a different perspective, the considered
subclasses of stochastic nets can be viewed as special classes of
synchronized queueing networks, thus the proposed bounds can be applied
to these networks.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/ccs-tse-91.pdf},
doi={10.1109/32.67593}
}

J. Campos, G. Chiola, and M. Silva, “Properties and Performance Bounds for Closed Free Choice Synchronized Monoclass Queueing Networks,” IEEE Transactions on Automatic Control, vol. 36, iss. 12, pp. 1368-1382, 1991.
[Bibtex]

@ARTICLE{CCS-TAC-91,
author = {J. Campos and G. Chiola and M. Silva},
title = {Properties and Performance Bounds for Closed Free Choice Synchronized
Monoclass Queueing Networks},
journal = {IEEE Transactions on Automatic Control},
year = {1991},
volume = {36},
pages = {1368-1382},
number = {12},
month = {December},
abstract = {Several proposals exist for the introduction of synchronization constraints
into Queueing Networks (QN). We show that many monoclass QN with
synchronizations can naturally be modelled with a subclass of Petri
Nets (PN) called Free Choice nets (FC), for which a wide gamut of
qualitative behavioural and structural results have been derived.
We use some of these net theoretic results to characterize the ergodicity,
boundedness and liveness of closed Free Choice Synchronized Queueing
Networks (FCSQN). Moreover we define upper and lower throughput bounds
based on the mean value of the service times, without any assumption
on the probability distributions (thus including both the deterministic
and the stochastic cases). We show that monotonicity properties exist
between the throughput bounds and the parameters of the model in
terms of population and service times. We propose (theoretically
polynomial and practically linear complexity) algorithms for the
computation of these bounds, based on linear programming problems
defined on the incidence matrix of the underlying FC net. Finally,
using classical laws from queueing theory, we provide bounds for
mean queue lengths and response time.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/ccs-tac-91.pdf},
doi={10.1109/9.106153}
}

J. Campos and M. Silva, “Throughput Upper Bounds for Markovian Petri Nets: Embedded Subnets and Queueing Networks,” in Proceedings of the 4rd International Workshop on Petri Nets and Performance Models, Melbourne, Australia, 1991, pp. 312-321.
[Bibtex]

@INPROCEEDINGS{CS-Melbourne-91,
author = {J. Campos and M. Silva},
title = {Throughput Upper Bounds for {Markovian} {Petri} Nets: Embedded Subnets
and Queueing Networks},
booktitle = {Proceedings of the 4rd International Workshop on Petri Nets and Performance
Models},
year = {1991},
pages = {312-321},
address = {Melbourne, Australia},
month = {December},
publisher = {IEEE-Computer Society Press},
abstract = {This paper addresses the computation of upper bounds for the steady-state
throughput of stochastic Petri nets with immediate and exponentially
distributed service times of transitions. We try to deeply bridge
stochastic Petri net theory to untimed Petri net and queueing network
theories. Previous results for general service time distributions
are improved for the case of Markovian nets by considering the slowest
embedded subnet (generated by the support of left annullers of the
incidence matrix of the net). The obtained results for the case of
live and bounded free choice nets are of special interest. For such
nets, the subnets generated by the left annullers of the incidence
matrix can be seen as embedded product-form closed monoclass queueing
networks, and efficient algorithms exist for their analysis.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cs-melbourne-91.pdf},
doi={10.1109/PNPM.1991.238789}
}

J. Campos, B. Sánchez, and M. Silva, “Throughput Lower Bounds for Markovian Petri Nets: Transformation Techniques,” in Proceedings of the 4rd International Workshop on Petri Nets and Performance Models, Melbourne, Australia, 1991, pp. 322-331.
[Bibtex]

@INPROCEEDINGS{CSS-Melbourne-91,
author = {J. Campos and B. S{\'a}nchez and M. Silva},
title = {Throughput Lower Bounds for {Markovian} {Petri} Nets: Transformation
Techniques},
booktitle = {Proceedings of the 4rd International Workshop on Petri Nets and Performance
Models},
year = {1991},
pages = {322-331},
address = {Melbourne, Australia},
month = {December},
publisher = {IEEE-Computer Society Press},
abstract = {This paper addresses the computation of lower bounds for the steady-
state throughput of stochastic Petri nets with immediate and exponentially
distributed service times of transitions. We try to deeply bridge
stochastic Petri net theory to untimed Petri net and queueing networks
theories. Previous results for general service time distributions
are improved for the case of Markovian nets by considering some pessimistic
transformation rules operating locally on the net structure, its
initial marking, and stochastic interpretation. Special interest
have the obtained results for the case of live and bounded free choice
nets and live marked graphs systems.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/css-melbourne-91.pdf},
doi={10.1109/PNPM.1991.238788}
}

J. Campos and M. Silva, “Steady-State Performance Evaluation of Totally Open Systems of Markovian Sequential Processes” in Decentralized Systems, M. Cosnard and C. Girault, Eds., Amsterdam, The Netherlands: Elsevier Science Publishers B.V. (North-Holland), 1990, pp. 427-438.
[Bibtex]

@INCOLLECTION{CS-DS-90,
author = {J. Campos and M. Silva},
title = {Steady-State Performance Evaluation of Totally Open Systems of {Markovian}
Sequential Processes},
booktitle = {Decentralized Systems},
publisher = {Elsevier Science Publishers B.V. (North-Holland)},
year = {1990},
editor = {M. Cosnard and C. Girault},
pages = {427-438},
address = {Amsterdam, The Netherlands},
abstract = {Totally open systems of Markovian sequential processes are defined
as a subclass of stochastic Petri nets. They can be viewed as a generalization
of a subclass of queueing networks in which complex sequential servers
can be synchronized according to some particular schemes. Structural
analysis of these nets is considered for avoiding the state explotion
problem of the embedded Markov chain. Some qualitative properties
interesting from a performance point of view are presented. In particular,
a "potential ergodicity'' property is characterized by means of two
structural properties: consistency and synchronic distance relation.
Necessary and sufficient ergodicity conditions and the computation
of steady-state performance measures are studied.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cs-ds-90.pdf},
doi={}
}

J. Campos, “Performance Bounds for Synchronized Queueing Networks,” PhD Thesis, Research Report GISI-RR-90-20, 1990.
[Bibtex]

@PHDTHESIS{Campos-thesis-90,
author = {J. Campos},
title = {Performance Bounds for Synchronized Queueing Networks},
school = {Departamento de Ingenier{\'{\i}}a El{\'e}ctrica e Inform{\'a}tica,
Universidad de Zaragoza, Spain},
year = {1990},
address = {Research Report GISI-RR-90-20},
month = {October},
abstract = {Product form queueing networks have long been used for the performance
evaluation of computer systems. Their success has been due to their
capability of naturally expressing sharing of resources and queueing,
that are typical situations of traditional computer systems, as well
as to their efficient solution algorithms, of polynomial complexity
on the size of the model. Unfortunately, the introduction of synchronization
constraints usually destroys the product form solution, so that general
concurrent and distributed systems are not easily studied with this
class of models. Petri nets have been proved specially adequate to
model parallel and distributed systems. Moreover, they have a well-founded
theory of analysis that allows to investigate a great number of qualitative
properties of the system. In the original definition, Petri nets
did not include the notion of time, and tried to model only the logical
behaviour of systems by describing the causal relations existing
among events. This approach showed its power in the specification
and analysis of concurrent systems in a way independent of the concept
of time. Nevertheless the introduction of a timing specification
is essential if we want to use this class of models for the performance
evaluation of distributed systems. One of the main problems in the
actual use of timed and stochastic Petri net models for the quantitative
evaluation of large systems is the explosion of the computational
complexity of the analysis algorithms. In general, exact performance
results are obtained from the numerical solution of a continuous
time Markov chain, whose dimension is given by the size of the state
space of the model. Structural computation of exact performance measures
has been possible for some subclasses of nets such as those with
state machine topology. These nets, under certain assumptions on
the stochastic interpretation are isomorphic to Gordon and Newell's
networks, in queueing theory terminology. In the general case, efficient
methods for the derivation of performance measures are still needed.
Two complementary approaches to the derivation of exact measures
for the analysis of distributed systems are the utilization of approximation
techniques and the computation of bounds. Approximate values for
the performance parameters are in general more efficiently derived
than the exact ones. On the other hand, "exactness'' only exists
in theory! In other words, numerical algorithms must be applied in
practice for the computation of exact values, therefore making errors
is inevitable. Performance bounds are useful in the preliminary phases
of the design of a system, in which many parameters are not known
accurately. Several alternatives for those parameters should be quickly
evaluated, and rejected those that are clearly bad. Exact (and even
approximate) solutions would be computationally very expensive. Bounds
become useful in these instances since they usually require much
less computation effort. The computation of upper and lower bounds
for the steady-state performance of timed and stochastic Petri nets
is considered in this work. In particular, we study the throughput
of transitions, defined as the average number of firings per time
unit. For this measure we try to compute upper and lower bounds in
polynomial time on the size of the net model, by means of proper
linear programming problems defined from the incidence matrix of
the net (in this sense, we develop structural techniques). These
bounds depend only on the mean values and not on the higher moments
of the probability distribution functions of the random variables
that describe the timing of the system. The independence of the probability
distributions can be viewed as a useful generalization of the performance
results, since higher moments of the delays are usually unknown for
real cases, and difficult to estimate and assess. From a different
perspective, the obtained results can be applied to the analysis
of queueing networks extended with some synchronization schemes.
Monoclass queueing networks can be mapped on stochastic Petri nets.
On the other hand, stochastic Petri nets can be interpreted as monoclass
queueing networks augmented with synchronization primitives. Concerning
the presentation of this manuscript, it should be mentioned that
chapter 1 has been written with the object of giving the reader an
outline of the stochastic Petri net model: its definition, terminology,
basic properties, and related concepts, together with its deep relation
with other classic stochastic network models. Chapter 2 is devoted
to the presentation of the net subclasses considered in the rest
of the work. The classification presented here is quite different
from the one which is usual in the framework of Petri nets. The reason
lies on the fact that our classification criterion, the computability
of visit ratios for transitions, is introduced for the first time
in the field of stochastic Petri nets in this work. The significance
of that criterion is based on the important role that the visit ratios
play in the computation of upper and lower bounds for the performance
of the models. Nevertheless, classical important net subclasses are
identified here in terms of the computability of their visit ratios
from different parameters of the model. Chapter 3 is concerned with
the computation of reachable upper and lower bounds for the most
restrictive subclass of those presented in chapter 2: marked graphs.
The explanation of this fact is easy to understand. The more simple
is the model the more accessible will be the techniques an ideas
for the development of good results. Chapter 4 provides a generalization
for live and bounded free choice nets of the results presented in
the previous chapter. Quality of obtained bounds is similar to that
for strongly connected marked graphs: throughput lower bounds are
reachable for bounded nets while upper bounds are reachable for 1-bounded
nets. Chapter 5 considers the extension to other net subclasses,
like mono-T-semiflow nets, FRT-nets, totally open deterministic systems
of sequential processes, and persistent nets. The results are of
diverse colours. For mono-T-semiflow nets and, therefore, for general
FRT-nets, it is not possible (so far) to obtain reachable throughput
bounds. On the other hand, for bounded ordinary persistent nets,
tight throughput upper bounds are derived. Moreover, in the case
of totally open deterministic systems of sequential processes the
exact steady-state performance measures can be computed in polynomial
time on the net size. In chapter 6 bounds for other interesting performance
measures are derived from throughput bounds and from classical queueing
theory laws. After that, we explore the introduction of more information
from the probability distribution functions of service times in order
to improve the bounds. In particular, for Coxian service delay of
transitions it is possible to improve the throughput upper bounds
of previous chapters which held for more general forms of distribution
functions. This improvement shows to be specially fruitful for live
and bounded free choice nets. Chapter 7 is devoted to case studies.
Several examples taken from literature in the fields of distributed
computing systems and manufacturing systems are modelled by means
of stochastic Petri nets and evaluated using the techniques developed
in previous chapters. Finally, some concluding remarks and considerations
on possible extensions of the work are presented.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/campos-thesis-90.pdf},
doi={}
}

J. Campos, J. M. Colom, and M. Silva, “Performance Evaluation of Repetitive Automated Manufacturing Systems,” in Proceedings of the Rensselaer’s Second International Conference on Computer Integrated Manufacturing, Rensselaer Polytechnic Institute, Troy, NY, USA, 1990, pp. 74-81.
[Bibtex]

@INPROCEEDINGS{CCS-Rensselaer-90,
author = {J. Campos and J.M. Colom and M. Silva},
title = {Performance Evaluation of Repetitive Automated Manufacturing Systems},
booktitle = {Proceedings of the Rensselaer's Second International Conference on
Computer Integrated Manufacturing},
year = {1990},
pages = {74-81},
address = {Rensselaer Polytechnic Institute, Troy, NY, USA},
month = {May},
publisher = {IEEE-Computer Society Press},
abstract = {Steady-state performance evaluation of some repetitive automated manufacturing
systems modelled by means of stochastic or deterministic timed Petri
nets is considered. Basically, concepts and techniques developed
by the authors in other works are applied to repetitive manufacturing
systems in this paper. Linear programming problems defined on the
incidence matrix of the underlying Petri nets are used to compute
tight upper and lower bounds for the performance measures of job-shop
systems and decision-free kanban systems in polynomial time on the
net structure. The results can be extended to other models in which
some decisions are allowed, such as producer-consumer systems with
mutual exclusion. Exact performance measures for a class of systems
containing sequential processes can be computed in polynomial time.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/ccs-rensselaer-90.pdf},
doi={10.1109/CIM.1990.128074}
}

J. M. Colom, J. Campos, and M. Silva, “On liveness analysis through linear algebraic techniques,” in Proceedings of the Annual General Meeting of ESPRIT Basic Research Action 3148 Design Methods Based on Nets (DEMON), Paris, France, 1990.
[Bibtex]

@INPROCEEDINGS{CCS-DEMON-90,
author = {J.M. Colom and J. Campos and M. Silva},
title = {On liveness analysis through linear algebraic techniques},
booktitle = {Proceedings of the Annual General Meeting of ESPRIT Basic Research
Action 3148 Design Methods Based on Nets (DEMON)},
year = {1990},
address = {Paris, France},
month = {June},
abstract = {Proving properties of Place/Transition Nets through Linear Algebraic
Techniques is very interesting because of the polynomial complexity
of the algorithms used for this purpose. In this sense, many works
have been devoted to the linear analysis of marking related properties
(e.g. boundedness of the state space, mutual exclusions, etc.). Nevertheless,
few results exist related to linear analysis of liveness properties.
In this note, we investigate some applications of linear techniques
to partial characterization of liveness properties. First, a necessary
condition for structural liveness in structural bounded nets is presented.
It is based on the rank of the incidence matrix. Finally, given an
initial marking, some sufficient conditions for dead transitions
and for deadlock-freeness are presented.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/ccs-demon-90.pdf}
}

J. Campos, G. Chiola, J. M. Colom, and M. Silva, “Tight Polynomial Bounds for Steady-State Performance of Marked Graphs,” in Proceedings of the 3rd International Workshop on Petri Nets and Performance Models, Kyoto, Japan, 1989, pp. 200-209.
[Bibtex]

@INPROCEEDINGS{CCCS-Kyoto-89,
author = {J. Campos and G. Chiola and J.M. Colom and M. Silva},
title = {Tight Polynomial Bounds for Steady-State Performance of Marked Graphs},
booktitle = {Proceedings of the 3rd International Workshop on Petri Nets and Performance
Models},
year = {1989},
pages = {200-209},
address = {Kyoto, Japan},
month = {December},
publisher = {IEEE Computer Society Press},
abstract = {The problem of computing both upper and lower bounds for the steady-state
performance of timed and stochastic Marked Graphs is studied. In
particular, Linear Programming problems defined on the incidence
matrix of the underlying Petri nets are used to compute tight (i.e.,
reachable) bounds for the throughput of transitions for live and
bounded Marked Graphs with time associated with transitions. These
bounds depend on the initial marking and the mean values of the delays
but not on the probability distributions (thus including both the
deterministic and the stochastic cases). Connections between results
and techniques typical of qualitative and quantitative analysis of
Petri models are stressed.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/cccs-kyoto-89.pdf},
doi={10.1109/PNPM.1989.68553}
}

J. Campos, G. Chiola, and M. Silva, “Properties and Steady-State Performance Bounds for Petri Nets with Unique Repetitive Firing Count Vector,” in Proceedings of the 3rd International Workshop on Petri Nets and Performance Models, Kyoto, Japan, 1989, pp. 210-220.
[Bibtex]

@INPROCEEDINGS{CCS-Kyoto-89,
author = {J. Campos and G. Chiola and M. Silva},
title = {Properties and Steady-State Performance Bounds for {Petri} Nets with
Unique Repetitive Firing Count Vector},
booktitle = {Proceedings of the 3rd International Workshop on Petri Nets and Performance
Models},
year = {1989},
pages = {210-220},
address = {Kyoto, Japan},
month = {December},
publisher = {IEEE Computer Society Press},
abstract = {The problem of computing both upper and lower bounds for the steady-state
performance of timed and stochastic Petri nets is studied. In particular,
Linear Programming problems defined on the incidence matrix of underlying
Petri net are used to compute bounds for the throughput of transitions
for live and bounded nets with a unique possibility of steady-state
behaviour. These classes of nets are defined and their characteristics
are studied. The bounds proposed here depend on the initial marking
and the mean values of the delays but not on the probability distributions
(thus including both the deterministic and the stochastic cases);
moreover they can be computed also for non-ergodic models. Connections
between results and techniques typical of qualitative and quantitative
analysis of Petri models are stressed.},
url = {http://webdiis.unizar.es/~jcampos/wordpress/wp-content/plugins/papercite/pdf/ccs-kyoto-89.pdf},
doi={10.1109/PNPM.1989.68554}
}

J. Campos and M. Silva, “Steady-State Performance Evaluation of Totally Open Systems of Markovian Sequential Processes,” in Proceedings of the Working Conference on Decentralized Systems, Lyon, France, 1989, pp. 559-585.
[Bibtex]

@INPROCEEDINGS{CS-Lyon-89,
author = {J. Campos and M. Silva},
title = {Steady-State Performance Evaluation of Totally Open Systems of {Markovian}
Sequential Processes},
booktitle = {Proceedings of the Working Conference on Decentralized Systems},
year = {1989},
pages = {559-585},
address = {Lyon, France},
month = {December},
publisher = {International Federation for Information Processing W.G.~10.3},
abstract = {Totally open systems of Markovian sequential processes are defined
as a subclass of stochastic Petri nets. They can be viewed as a generalization
of a subclass of queueing networks in which complex sequential servers
can be synchronized according to some particular schemes. Structural
analysis of these nets is considered for avoiding the state explotion
problem of the embedded Markov chain. Some qualitative properties
interesting from a performance point of view are presented. In particular,
a "potential ergodicity'' property is characterized by means of two
structural properties: consistency and synchronic distance relation.
Necessary and sufficient ergodicity conditions and the computation
of steady-state performance measures are studied.},
doi={}
}

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