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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Computational model for engineering design and development

Chuang, Wei Kuo January 1998 (has links)
No description available.
2

Contribution à la modélisation et à la commande des feux de signalisation par réseaux de Petri hybrides / Contribution to the modeling and control of traffic lights with hybrid Petri nets

Sammoud, Bassem 04 September 2015 (has links)
Le trafic routier entraine de nombreux effets néfastes, dont la pollution, l'insécurité et la congestion. La plupart de méthodes développées, pour la régulation du trafic urbain au niveau des carrefours, cherche à réduire les temps d’attente et les longueurs des files d'attente. Ces méthodes se fixent principalement comme objectif l’optimisation des cycles de feu sur un horizon fini.Pour la description du trafic, nous adoptons une modélisation par les réseaux de Pétri Hybrides (RdPH), qui représente, simultanément, deux niveaux de représentation complémentaires : l'évolution continue des files d'attente et l'évolution discrète des feux tricolores. Ces deux niveaux sont, respectivement, articulés autour des réseaux de Pétri à vitesses variables et des réseaux de Pétri discrets temporisés.Nous élaborons en plus, une nouvelle stratégie pour résoudre le problème de la régulation du trafic urbain intervenant d'une manière adaptée au niveau des feux de signalisation. Nous cherchons à éviter, en premier lieu,la congestion et la sursaturation des files d'attente, qui ne doivent pas dépasser l'optimum des capacités des voies de l'intersection et, en second lieu, à réduire le temps d'évacuation des véhicules au niveau du carrefour et surtout les temps d'attente des conducteurs.Dans ce sens, un premier algorithme est élaboré pour calculer les longueurs des files d'attente, utilisant une approche qui se base sur la simplification de la modélisation d'un carrefour. Pour optimiser le temps moyen d’attente et le temps total d'évacuation sont, considérés et appliqués, avec succès, une heuristique de contrôle et une stratégie de régulation à feux fixe et à feux variables, suite à la détermination de la durée de feu vert correspondante à la situation de l'intersection en temps réel.Nous envisageons, de généraliser les résultats de nos travaux exploitant le modèle RdPH aux intersections plus complexes pour des situations réelles d'un réseau de carrefour. / Road traffic causes many adverse effects, including pollution, insecurity and congestion. Most of the developedmethods for regulation of urban traffic at crossroads, seeking to reduce wait times and lengths of queues. Thesemethods are mainly set objective optimization fire cycles over a finite horizon.To describe the composition of traffic, we opted for a traffic modeling by hybrid Petri nets, representingsimultaneously two complementary levels of representation: the continuing evolution of queues and discreetchanging traffic lights. These two levels are respectively articulated about Petri nets variable speed and discretetimed Petri nets.We chose, as well, for a new strategy to solve the problem of urban traffic control intervening in an appropriatemanner to the level of the signal lights. We sought to avoid first, congestion and the super saturation of queues,which must not exceed the optimum capacity of the intersection of routes studied and, second, to reduce theevacuation time of vehicles at the crossroads and especially waiting times for drivers.In this sense, a first algorithm is developed to calculate the lengths of queues, using a modeling simplificationapproach to a junction. To optimize the average waiting time and the total evacuation time are considered andapplied successfully by a heuristic control lights and a fixed control strategy and floating lights, following thedetermination of the duration of corresponding green light to the situation in real time intersectionWe plan to generalize the results of our work exploiting RDPH model to complex intersections for real situations of acrossroads network.
3

Estudo e experimentação de uma linguagem de modelagem de sistemas baseada em redes de petri e orientação a objetos. / Study and experimentation of a system modeling language based on petri nets and object orientation.

CANEDO, Edna Dias. 18 September 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-18T16:35:32Z No. of bitstreams: 1 EDNA DIAS CANEDO - DISSERATAÇÃO PPGCC 2002..pdf: 967964 bytes, checksum: aee05fbebc2049f4cd9fb4dea8a9aa1d (MD5) / Made available in DSpace on 2018-09-18T16:35:32Z (GMT). No. of bitstreams: 1 EDNA DIAS CANEDO - DISSERATAÇÃO PPGCC 2002..pdf: 967964 bytes, checksum: aee05fbebc2049f4cd9fb4dea8a9aa1d (MD5) Previous issue date: 2002-08-29 / A integração da teoria de redes de Petri com os conceitos da Orientação Objetos surgiu como uma solução para a decomposição e estruturação de modelos em Redes de Petri. Neste trabalho é apresentado um estudo e experimentação de uma linguagem de modelagem baseada em redes de Petri e Orientação a Objetos (RPOO). RPOO foi definida integrando esses dois formalismos em uma perspectiva ortogonal, permitindo que o sistema modelado tenha duas visões: uma visão do ponto de vista de redes de Petri e uma visão do ponto de vista da Orientação a Objetos. O estudo e experimentação da notação RPOO é efetuado através da sua aplicação na modelagem de sistemas de software real. Para tanto, foram desenvolvidos alguns experimentos de modelagem. Assim, os experimentos desenvolvidos serão utilizados na validação da linguagem RPOO como alternativa para a estruturação e decomposição de modelos em redes de Petri, quando da modelagem de sistemas de software distribuídos e concorrentes. / The integration of Petri nets theory and object oriented-object concepts has emerged as a solution to decompose and structure Petri net models. In this work it is presented a study and experimentation of a modeling language based on Petri nets and oriented-object concepts(RPOO). RPOO was defined by integrating these two formalisms on an orthogonal perspective, allowing that the modeled system has two visions: one Petri net visionand one OO vision. The study and experimentation of RPOO notation is accomplished through its application on the modeling of real software systems. Some experiments of modeling had been developed. These experiments will be used to validate RPOO as an alternative for the structure and decomposition of Petri nets models, when modeling distributed and concurrent software systems.

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