Manuel silva
University of Zaragoza, Ingeniería Industrial, Faculty Member
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... more
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 ...
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... disregarded, either because other restric-tions guarantee the integrality of the marking or becausemixed integer linear ... marking to a greater or equal one (equal in case of boundedness) involving every transition, the firing ... If... more
... disregarded, either because other restric-tions guarantee the integrality of the marking or becausemixed integer linear ... marking to a greater or equal one (equal in case of boundedness) involving every transition, the firing ... If S is a live P/T system then A/" is structurally repetitive. ...
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UK PubMed Central (UKPMC) is an archive of life sciences journal literature.
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Two Heuristics for the Improvement of a ... Univ. of Zaragoza Techn. Univ. Berlin Univ. of Zaragoza ... Abstract - The Optimization of Man.ufacturing Sys-tems is computationally expensiue in most cases. A meta-heuristic (Simulated... more
Two Heuristics for the Improvement of a ... Univ. of Zaragoza Techn. Univ. Berlin Univ. of Zaragoza ... Abstract - The Optimization of Man.ufacturing Sys-tems is computationally expensiue in most cases. A meta-heuristic (Simulated Annealing) is considered here to control the onerall ...
The local optimality (LO) property for discrete event dynamic systems (DEDS) modeled using Petri nets (PNs) is presented. If a system is divided into independent subsystems and if the optimal behavior of these subsystems guarantees the... more
The local optimality (LO) property for discrete event dynamic systems (DEDS) modeled using Petri nets (PNs) is presented. If a system is divided into independent subsystems and if the optimal behavior of these subsystems guarantees the optimal behavior of the whole system, then this system possesses the LO property. The main advantage of this approach is that it is possible to find an optimal schedule for this class of systems in less time. A characterization of systems exhibiting the LO property, as well as a ...
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... JC Mugarza H. Camus J.-C. Gentina E. Teruel M. Silva Dpto. de Electrhica Lab. ... For scheduling problems, ie. controlling performance of the modelled system, a timed model is used. Thie firing of transitions is controlled in such a... more
... JC Mugarza H. Camus J.-C. Gentina E. Teruel M. Silva Dpto. de Electrhica Lab. ... For scheduling problems, ie. controlling performance of the modelled system, a timed model is used. Thie firing of transitions is controlled in such a way that some “optimal” behaviour is reached. ...
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Steady-state performance evaluation of some repetitive automated manufacturing systems previously modeled by means of stochastic or deterministic timed Petri nets is considered. Concepts and techniques previously developed by the authors... more
Steady-state performance evaluation of some repetitive automated manufacturing systems previously modeled by means of stochastic or deterministic timed Petri nets is considered. Concepts and techniques previously developed by the authors are applied to repetitive manufacturing systems. 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 ...
Research Interests: Operations Research, Linear Programming, Computer Aided Manufacturing, Petri Nets, Proceedings, and 13 moreStochastic processes, Performance Evaluation, computer Integrated manufacturing, Steady state, Petri Net, Job Shop, Mutual Exclusion, Manufacturing System, Polynomials, Performance Measure, LINEAR PROGRAM, Time measurement, and Polynomial Time
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Research Interests: Behavior, Risk, Adolescent, Portugal, Pregnancy, and 4 moreHumans, Female, Newborn Infant, and Maternal Age
Forrester diagrams (FD) and Petri nets (PN) are formalisms introduced in the sixties to model complex systems. This paper explores similarities and differences between FDs and the continuous relaxation of the originally discrete PNs.... more
Forrester diagrams (FD) and Petri nets (PN) are formalisms introduced in the sixties to model complex systems. This paper explores similarities and differences between FDs and the continuous relaxation of the originally discrete PNs. Historically speaking, the approaches were quite different: the PNs paradigm was introduced at a very abstract level, without timing interpretation, while FDs led to a modelling methodology where the systematic simulation of a set of differential equations was the goal. Strict flow conservation around valves, non explicit fork and join operations, separation of information and material flows, are peculiarities of FDs. In PN models the existence of global conservation laws is a potential for structural analysis
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Petri nets is a well-know formalism for studying discrete event systems. Applications include performance evaluation in communication networks, production systems, supply chains, and the implementation of sequence controllers. Timed... more
Petri nets is a well-know formalism for studying discrete event systems. Applications include performance evaluation in communication networks, production systems, supply chains, and the implementation of sequence controllers. Timed Continuous Petri Net (TCPN) systems are continuous-state models that can approximate the dynamical behavior of discrete Markovian Petri nets (MPN). Based on this, an estimator-based control structure is introduced here for
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In the area around the estuary of the Sado River the steel casing of some wells is corroded or deteriorat- ed due to the corrosive environment in the salty Pliocene aquifer. The casing rupture allows water from this aquifer to communicate... more
In the area around the estuary of the Sado River the steel casing of some wells is corroded or deteriorat- ed due to the corrosive environment in the salty Pliocene aquifer. The casing rupture allows water from this aquifer to communicate directly with the underlying fresh water Miocene aquifer and contaminate it through a process known as interaquifer exchange. Groundwater vertical movement occurs under natural hydraulic gradients induced by the fresh water abstrac- tion. Electric resistance and temperature logging of the water column in the wells were the methods used to identify ruptures in the well casing and to provide infor- mation on the movement of water through the wells.
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Résumé La zone étudiée fait partie des zones arides du Maroc, avec des précipitations inférieures à 300mm. Elle est située à une quarantaine de kilomètres au sud d'Essaouira. Elle s'étend depuis l'anticlinal d'Amsittène au... more
Résumé La zone étudiée fait partie des zones arides du Maroc, avec des précipitations inférieures à 300mm. Elle est située à une quarantaine de kilomètres au sud d'Essaouira. Elle s'étend depuis l'anticlinal d'Amsittène au nord à l'oued Igouzoullene au sud, sur 100 km 2 et compte environ 40 000 habitants répartis en plusieurs villages.L'étude des affleurements (lithologie et structure) ainsi que celle des sondages mécaniques a permis de distinguer plusieurs niveaux aquifères dans la zone côtière d'Essaouira. Parmi les unités hydrostratigraphiques, l'Hautérivien reste l'un des niveaux les plus importants par ses caractéristiques lithologiques et structurales. Sur le plan hydrodynamique, l'impact de la sécheresse qu'a connu le Maroc ces deus dernières décennies n'a pas eu le même effet sur l'aquifère Hautérivien en comparaison avec d'autres aquifères de la région étudiée où on a assisté à une baisse généralisée des niveaux piézom...
In the urban area of Estoril, a Portuguese tourist village 20 km westward from Lis-bon, hot mineral waters (thermal waters) spout out from natural springs which have been known since the 19th century. The thermal waters are of the sodium... more
In the urban area of Estoril, a Portuguese tourist village 20 km westward from Lis-bon, hot mineral waters (thermal waters) spout out from natural springs which have been known since the 19th century. The thermal waters are of the sodium chloride type, with total dissolved solids and temperatures higher than the ones of the regional waters. Iso-topic data are consistent with a meteoric origin for both the regional and thermal waters of the Estoril area: 8 18 0 (%0), --4.16 to -3.52 and 8 2 H (%0), -25.5 to -18.7. The thermal water composition can be derived from the regional water composition assuming the dis-solution of evaporite minerals, cation exchange and precipitation of calcite. The thermal water flow system has probably the recharge area somewhere in between Estoril and the Sintra mountain. The elevation difference between the recharge area and the sea pro-vides the driving force for groundwater movement to the Estoril area where the upward movement of the mineralised and wa...
Research Interests: Geology()
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Le Système aquifère TEJO-SADO est le plus grand aquifère et de loin le plus important du Portugal. Il occupe la partie basse tertiaire des deux fleuves Tejo et Sado, sur une superficie approximative de 8550 km2 et comprend un système... more
Le Système aquifère TEJO-SADO est le plus grand aquifère et de loin le plus important du Portugal. Il occupe la partie basse tertiaire des deux fleuves Tejo et Sado, sur une superficie approximative de 8550 km2 et comprend un système multicouche constitué de dépots tertiaires surmontés par des dépots quaternaires. Au sein de cet aquifère, il y a des captages importants qui pourvoient en eau, aussi bien industrielle, qu’agricole et domestique, notamment pour la métropole Lisboa. Le bilan du système aquière, proposé par GESTÁGUA (1996), et calculé par un modèle en différences finis, a un débit total de 29,55 m3/s. Les dépôts sédimentaires cénozoiques de Tejo-Sado ont une épaisseur presque 800 mètres á dominanace détritique, d’origine continentale, avec quelques intercalations de dépots marins carbonatés. Le bassin sédimentaire du bas Tejo corespond á une dépression tectonique qui a résulté des subsidents controlés par des failles durant le néogène. Il se présente comme grosso-modo un ...
Neste artigo pretende-se analisar as práticas criminais de indivíduos de etnia cigana, através do estudo das suas trajetórias de vida. Com base em 25 entrevistas a reclusos/as ciganos/as, analisou-se as suas condições de vida objetivas e... more
Neste artigo pretende-se analisar as práticas criminais de indivíduos de etnia cigana, através do estudo das suas trajetórias de vida. Com base em 25 entrevistas a reclusos/as ciganos/as, analisou-se as suas condições de vida objetivas e experiências criminais, à luz da interseção de variáveis de classe, género e etnia. Concluímos que os crimes neste grupo étnico resultam da articulação de processos de exclusão ou desigualdades sociais, de preconceitos ou racismo, e que as interseções de classe, género e etnia coestruturam fortemente as suas condições objetivas de vida e o seu envolvimento criminal. Palavras-chave: criminalidade; etnia cigana; trajetórias de vida. Life Conditions and trajectories of male and female Roma prisoners in Portugal This paper aims to analyze the criminal practices of Roma individuals through the study of their life histories. Based on 25 interviews addressed to male and female Roma prisoners, we analyzed their objective life conditions and criminal experie...
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Situated about 900 km southwest of mainland Portugal, in the North Atlantic, Madeira is the bigger and more populated island of the archipelago with the same name. It has a total area of 747 km2 and its northern slope forms a barrier that... more
Situated about 900 km southwest of mainland Portugal, in the North Atlantic, Madeira is the bigger and more populated island of the archipelago with the same name. It has a total area of 747 km2 and its northern slope forms a barrier that opposes the prevailing north-easterly trade winds, thus resulting in a very frequent windward fog belt, between 800-1600 a.s.l. Madeira has a 125 km2 area of indigenous altitude forests inside the windward fog belt, between 800-1600 a.s.l. (Prada et al., 2008). This area is characterized by very steep slopes, mainly exposed to the prevailing winds. When combined, factors like steep slopes, great exposure to the humid trade winds and presence of forest vegetation facilitate fog precipitation. This is why we assume that fog precipitation is a generalized phenomenon throughout Madeira's northern slope area. To ascertain whether or not fog water contributes to groundwater recharge, a study on the stable isotopic composition was made. For that purpo...
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... 10801089. 10. WN Hubbard, DW Scott and G. Waddington. In: FD Rossini, Editor, Experimental Thermochemistry, Interscience, New York (1956). 11. ... 19. JB Pedley, RD Naylor and SP Kirby. Thermochemical Data of Organic Compounds,... more
... 10801089. 10. WN Hubbard, DW Scott and G. Waddington. In: FD Rossini, Editor, Experimental Thermochemistry, Interscience, New York (1956). 11. ... 19. JB Pedley, RD Naylor and SP Kirby. Thermochemical Data of Organic Compounds, Chapman and Hall, London (1986). ...
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Ingenieria de Sistemas e InformAtica ETS de Ingenieros Industriales, Universidad de Zaragoza Maria Zambrano 50 (Actur), 50015 Zaragoza (Spain) ... Abstract: This paper discusses the design of the coordination subsystem of a Flexible... more
Ingenieria de Sistemas e InformAtica ETS de Ingenieros Industriales, Universidad de Zaragoza Maria Zambrano 50 (Actur), 50015 Zaragoza (Spain) ... Abstract: This paper discusses the design of the coordination subsystem of a Flexible Manufacturing System (FMS) and its ...
Research Interests: Automatic Control, Petri Nets, Control Systems, Stochastic processes, Model validation, and 11 moreProduction Systems, Real Time Systems, Real Time Scheduling, Software Implementation, expert System, Colored Petri Net, Job shop scheduling, Integrated Motion Control, Genetic analysis for qualitative and quantitative traits of crop plants, Production System, and Robotics Automation
Petri nets (PNs) constitute a formal paradigm for discrete systems. Some discrete models can be relaxed into continuous models. Infinite server semantics continuous Petri nets (ISSCPNs) is one of the most relevant timed interpretation of... more
Petri nets (PNs) constitute a formal paradigm for discrete systems. Some discrete models can be relaxed into continuous models. Infinite server semantics continuous Petri nets (ISSCPNs) is one of the most relevant timed interpretation of Continuous PNs. ISSCPNs can be seen as piecewise linear systems. Forrester Diagrams (FD) are specific modelling tools inside System Dynamics, a methodology for the analysis
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Haloketones (HKs) are unregulated volatile disinfection by-products that show some potential risk even at low concentrations. While EPA Method 551.1 involves conventional liquid-liquid extraction and a complex series of steps, the simple... more
Haloketones (HKs) are unregulated volatile disinfection by-products that show some potential risk even at low concentrations. While EPA Method 551.1 involves conventional liquid-liquid extraction and a complex series of steps, the simple scientific principles of solid-phase microextraction (SPME) in the headspace (HS) mode can be applied to ensure a solvent-free method to control these substances at appropriate levels. The 14 HKs (12mL of water at pH∼1.5) were extracted on a DVB/CAR/PDMS fibre in 15min. After extraction, the analytes were desorbed at 250°C in the GC-MS inlet. Parameters affecting the extraction/desorption steps were investigated to select the most favourable conditions in short times. The HS-SPME/GC-MS method demonstrated high extraction efficiency with low limits of detection of between 15 and 600ng/L, good linearity in the range 0.05-2μg/L to 100-2000μg/L, and good repeatability (RSD below 7%, n=11). The green method was validated with EPA 551.1, used for determining halogenated VOCs in water, with noticeable advantages in terms of sensitivity, simplicity and solvent consumption. The results obtained from the analysis of water taken from a treatment plant employing chlorine dioxide and chloramines as disinfectants showed that two HKs were formed after pre-oxidation and that the subsequent steps in the plant were ineffective for their removal. Finally, the analysis of tap and swimming pool water exhibited that the concentration and number of species formed is higher in the latter, which is in accordance with its higher concentration of residual chlorine and organic matter.
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Paper about urbanization and urbanists in XIX century Spain. The paper research on the two regards upon urban spaces in several ways: inner cities reform vs outside planned expansion, engineers cartography and town planning against... more
Paper about urbanization and urbanists in XIX century Spain. The paper research on the two regards upon urban spaces in several ways: inner cities reform vs outside planned expansion, engineers cartography and town planning against architectural regards; public infraestructures and municipal monuments, The founder of urbnization concept and Ildefons Cerdà,, author of the Barcelona Expansion, (Eixample) is rerviewed