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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.
191

Modelling and programming embedded controllers with timed automata and synchronous languages

Bourke , Timothy Peter, Computer Science & Engineering, Faculty of Engineering, UNSW January 2009 (has links)
Embedded controllers coordinate the behaviours of specialised hardware components to satisfy broader application requirements. They are difficult to model and to program. One of the greatest challenges is to express intricate timing behaviours???which arise from the physical characteristics of components???while not precluding efficient implementations on resource-constrained platforms. Aspects of this challenge are addressed by this thesis through four distinct applications of timed automata and the synchronous languages Argos and Esterel. A novel framework for simulating controllers written in an imperative synchronous language is described. It includes a transformation of synchronous models into timed automata that accounts for timing properties which are important in constrained implementations but ignored by the usual assumption of synchrony. The transformation provides an interface between the discrete time of synchronous programs and a continuous model of time. This interface is extended to provide a way for simulating Argos programs within the widely-used Simulink software. Timed automata are well-suited for semantic descriptions, like the aforementioned transformation, and for modelling abstract algorithms and protocols. This thesis also includes a different type of case study. The timing diagram of a small-scale embedded component is modelled in more detail than usual with the aim of studying timing properties in this type of system. Multiple models are constructed, including one of an assembly language controller. Their interrelations are verified in Uppaal using a construction for timed trace inclusion testing. Existing constructions for testing timed trace inclusion do not directly address recent features of the Uppaal modelling language. Novel solutions for the problems presented by selection bindings, quantifiers, and channel arrays in Uppaal are presented in this thesis. The first known implementation of a tool for automatically generating a timed trace inclusion construction is described. The timed automata case study demonstrates one way of implementing application timing behaviours while respecting implementation constraints. A more challenging, but less detailed, example is proposed to evaluate the adequacy of Esterel for such tasks. Since none of the standard techniques are completely adequate, a novel alternative for expressing delays in physical time is proposed. Programs in standard Esterel are recovered through syntactic transformations that account for platform constraints.
192

Μελέτη και κατασκευή συστήματος μετατροπής της τάσεως εξόδου συστοιχίας κυψελών καυσίμου σε τριφασική εναλλασσόμενη για τον έλεγχο σύγχρονης μηχανής με μόνιμο μαγνήτη

Μώρος, Αντώνιος 07 December 2010 (has links)
Αντικείμενο της εργασίας είναι η μελέτη και κατασκευή διάταξης μετατροπής συνεχούς τάσης σε τριφασική εναλλασσόμενη, προκειμένου να χρησιμοποιηθεί για τον έλεγχο σύγχρονης μηχανής με μόνιμο μαγνήτη. Συγκεκριμένα, χρησιμοποιήθηκε μια μηχανή «brushless» με μόνιμο μαγνήτη ως κινητήρας και ως φορτίο αυτής μια δεύτερη μηχανή, συνεχούς ρεύματος με μόνιμο μαγνήτη, που λειτούργησε ως γεννήτρια. Ο έλεγχος της πρώτης μηχανής πραγματοποιήθηκε με έναν ηλεκτρονικό μετατροπέα ισχύος συνεχούς τάσης σε τριφασική εναλλασσόμενη. Αναλυτικά, στο κεφάλαιο 1 γίνεται αναφορά στους μόνιμους μαγνήτες που χρησιμοποιούνται στην κατασκευή μηχανών «brushless». Αναλύονται θεμελιώδεις μαγνητικές έννοιες και μαγνητικές ιδιότητες των υλικών. Στο κεφάλαιο 2 γίνεται εκτενής περιγραφή της λειτουργίας μιας μηχανής «brushless» με μόνιμο μαγνήτη. Αναλύονται τα κατασκευαστικά χαρακτηριστικά της, οι διαφορές της από άλλες κλασσικές μηχανές, καθώς και η αρχή λειτουργίας της. Στο κεφάλαιο 3 αναλύεται το μαθηματικό μοντέλο που διέπει τη λειτουργία της μηχανής: τα μαγνητικά πεδία της, οι σκεδάσεις, οι τάσεις εξ’επαγωγής και οι ηλεκτρομαγνητικές ροπές. Στο κεφάλαιο 4 περιγράφεται το σύστημα τροφοδοσίας και ελέγχου της μηχανής. Στο κεφάλαιο 5 προσομοιώνεται το υπό μελέτη σύστημα μέσω του προγράμματος simulink. Αρχικά προσομοιώνεται η απόκριση της μηχανής «brushless» υπό διαφορετικές ροπές φορτίου και εν τέλει γίνεται προσομοίωση του συστήματος που περιλαμβάνει αντιστροφέα με διαμόρφωση παλμών PWM και τη μηχανή. Στο κεφάλαιο 6 αναλύεται η πειραματική διάταξη που χρησιμοποιήθηκε για την πραγματοποίηση των μετρήσεων και παρουσιάζονται τα αποτελέσματα από τις μετρήσεις. Κυρίως παρουσιάζονται τα παλμογραφήματα τα οποία προέκυψαν κατά τη λειτουργία του συστήματος. Τέλος, καταγράφεται η βιβλιογραφία που χρησιμοποιήθηκε και στα παραρτήματα ενσωματώνονται τα φυλλάδια των κατασκευαστών των μηχανών που χρησιμοποιήθηκαν για τη συγκρότηση του υπό μελέτη πειραματικού συστήματος. / -
193

Υπερτάσεις σε δίκτυα χαμηλής τάσης λόγω πτώσης κεραυνών

Μπριζόλης, Αλέξανδρος 24 October 2012 (has links)
Στην παρούσα διπλωματική εργασία εξετάζεται το φαινόμενο του κεραυνού και οι επιπτώσεις αυτού του φαινομένου στα δίκτυα ηλεκτρικής ενέργειας. Για καλύτερη κατανόηση των διαφόρων ηλεκτρικών φαινομένων μοντελοποιήθηκε ένα τριφασικό δίκτυο μέσης και χαμηλής τάσης έτσι ώστε να εξαχθούν μετρήσεις που αντικατοπτρίζουν τις επιπτώσεις που έχουν τα κεραυνικά πλήγματα στον εξοπλισμό και στο φορτίο του δικτύου. Στο Κεφάλαιο 1 γίνεται μία σύντομη εισαγωγή στο φαινόμενο του κεραυνού. ΣτοΚεφάλαιο 2 δίνεται ένας ορισμός για να περιγραφεί ακριβέστερα το φαινόμενο του κεραυνού και παρουσιάζονται τα διάφορα είδη του. Στο Κεφάλαιο 3 μελετούνται τα ηλεκτρικά χαρακτηριστικά ενός κεραυνού οπότε παρουσιάζονται λεπτομερώς θέματα που έχουν να κάνουν με το ρεύμα, την τάση και το φορτίο που μπορεί να οδηγήσει ένας κεραυνός. Στο Κεφάλαιο 4 μελετούνται οι επιπτώσεις που προκαλούνται από κεραυνούς τόσο στη φύση όσο και στις τεχνικές υποδομές της περιοχής όπου πέφτει ο κεραυνός. Στο Κεφάλαιο 5 εισάγεται ο αναγνώστης στη θεωρία δικτύων ηλεκτρικής ενέργειας ενώ στο Κεφάλαιο 6 γίνεται εισαγωγή στη θεωρία υπερτάσεων. Στο Κεφάλαιο 7 παρουσιάζεται αναλυτικά το μοντέλο προσομοιώσεων που αναπτύχθηκε στα πλαίσια της εργασίας χρησιμοποιώντας το περιβάλλον προσομοίωσης Matlab/Simulink, παρατίθενται οι μετρήσεις που εξήχθησαν και παρουσιάζονται τα τελικά συμπεράσματα του πρακτικού μέρους της εργασίας. / This thesis examines the phenomenon of lightning and the effectsof this phenomenon in electricity networks. For a better understanding of the various electrical phenomena modeled a three-phase network medium and low voltage so as to extract measurements that reflect the impact of the lightning strike on equipment and network load. Chapter 1 gives a brief introduction to the lightning strike. Chapter 2 gives a definition to describ eaccurately the lightning strike and presents the various types of this. In Chapter 3 we study the electrical characteristics of a lightning strike. Are presented in detail issues that have to do with the current, voltage and the load can lead thunder bolt. In Chapter 4 we study the effects caused by lightning strike in both nature and the technical infrastructure of the area where the lightning falls. Chapter 5 introduces the reader to the theory of electricity networks while Chapter 6 is introduced in the theory over voltages. Chapter 7 presents detailed simulation model developed in this thesis using the simulation environment Matlab / Simulink, given the measurements obtained are presented and the final conclusions of the practical part of the work.
194

Modelación de un Compensador Estático para el Control de Generación Distribuida con Energías Renovables

Díaz Duarte, Christian Alejandro January 2009 (has links)
El presente trabajo consiste en la modelación de un compensador estático para el control de generación distribuida con energías renovables. El objetivo es que esta modelación represente una microred básica en la cual se pueda observar el comportamiento de un pequeño medio de generación, como por ejemplo una micro turbina hidráulica, en un ambiente de generación distribuida. El modelo debe ser capaz de simular requerimientos violentos de potencia y, también, el control, como por ejemplo un compensador estático, diseñado para mitigar los efectos negativos que esto trae, como por ejemplo problemas de frecuencia y voltaje. Se busca obtener un modelo sencillo e implementarlo con el software Matlab a través de su herramienta de simulación con entorno gráfico Simulink con la ayuda de las herramientas disponibles en el Toolbox SimPowerSystems. Con el fin de contextualizar los conceptos de generación distribuida, energías renovables y equipos de compensación estáticos, se hace una revisión del contexto mundial sobre el problema energético y las medidas que se han adoptado en otros países como la liberalización del mercado energético para la integración de generación distribuida. Se presentan las alternativas comunes que se utilizan hoy en día para el control de generación desde las más sencillas hasta las más elaboradas. También se revisan los distintos tipos de equipos de compensación FACTS, en particular los equipos de compensación de potencia activa y los sistemas de almacenamiento de energía, existentes en el mercado. Para poder introducir el modelo en Matlab-Simulink, se presentan algunos esquemas de control típicos para equipos STATCOM y SVC en los que está basada la modelación y los bloques que conforman el sistema de control simulado. El modelo diseñado, fue ajustado para trabajar en una microred en presencia de una carga resistiva y una carga inductiva que es conectada a la microred mediante un interruptor trifásico. La carga inductiva fue conectada 0.5 segundos después del inicio de la simulación provocando una baja de tensión en la línea hasta los 0.92[pu] que es restablecida hasta su valor unitario en aproximadamente 0.16[s] por la acción del dispositivo modelado. Se concluye que el esquema de STATCOM basado en inversores VSI presentan características operativas atractivas para la generación distribuida dada su rapidez de respuesta y la posibilidad de aportar su capacidad nominal en condiciones severas de funcionamiento.
195

Desenvolvimento da ferramenta MS2PSOC: Tradução de modelos descritos no matlab/simulink para o ambiente psoc creator

Almeida, Alexandre Araujo Amaral de [UNESP] 02 September 2015 (has links) (PDF)
Made available in DSpace on 2015-12-10T14:22:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-09-02. Added 1 bitstream(s) on 2015-12-10T14:28:53Z : No. of bitstreams: 1 000854162.pdf: 1819878 bytes, checksum: 183fc5505e1e32f889ee3f7f7e59324e (MD5) / Usualmente, realiza-se a modelagem de um sistema no Simulink e, posteriormente, no PSoC Creator para implement ́a-lo no hardware PSoC. Neste trabalho apresenta-se a ferramenta computacional denominada MS 2 PSoC que analisa um modelo desenvolvido em alto n ́ıvel de abstra ̧c a ̃ o no ambiente Matlab/Simulink e o traduz para o ambiente PSoC Creator. A tradu ̧c a ̃ o tem por finalidade a implementa ̧c ̃ao do modelo no sistema embarcado utilizando a tecnologia PSoC. No processo de tradu ̧c a ̃ o, a ferramenta MS 2 PSoC tamb ́em gera a estrutura de arquivos necess ́aria para que o modelo traduzido seja aberto no ambiente PSoC Creator. A inova ̧c a ̃ o deste trabalho ́e permitir que o modelo possa ser simulado antes de ser implementado em hardware, haja vista que o ambiente PSoC Creator n ̃ao disp ̃oe de simulador. Como estudo de casos utilizou-se o c ́odigo de linha MLT-3, um modelo de conversor D/A Ladder R-2R e um sistema de controle de temperatura veicular. Os sistemas estudados foram implementados em hardware e avaliados, comparando-os com os resultados obtidos nas simula ̧c ̃oes no Simulink. Com os resultados obtidos concluiu- se que a ferramenta MS 2 PSoC traduz corretamente os modelos descritos no ambiente Matlab/Simulink para o ambiente PSoC Creator, automatizando a implementa ̧c a ̃ o de modelos no sistema embarcado PSoC / Usually, a system is modeled in Simulink and later in PSoC Creator to deploy it in hardware PSoC. We present in this work a computational tool called MS 2 PSoC which analyses a model developed at a high level of abstraction in Matlab/Simulink and translates it to the PSoC Creator software. The goal of this translation is to implement the model in embedded system with PSoC technology. In the translation process, the MS 2 PSoC tool also generates the file structure needed for the translated model to be open in PSoC Creator. The innovation of this work is to allow the model to be simulated before it is implemented in hardware, given that the PSoC Creator software has no simulator. As a case study was used a MLT-3 line code, a D/A converter Ladder R-2R and a temperature control system for vehicles. The systems were implemented in PSoC hardware and evaluated by comparing them with the results obtained in the Simulink simulations. With the results it was concluded that the tool MS 2 PSoC correctly translates the models described in Matlab/Simulink environment for PSoC Creator, automating the deployment models in embedded system PSoC
196

The vulnerability of laser warning systems against guided weapons based on low power lasers

Al-Jaberi, Mubarak January 2006 (has links)
Laser assisted weapons, such as laser guided bombs, laser guided missiles and laser beam-riding missiles pose a significant threat to military assets in the modern battlefield. Laser beam-riding missiles are particularly hard to detect because they use low power lasers. Most laser warning systems produced so far can not detect laser beam-riding missiles because of their weak emissions which have signals less than 1% of laser range finder power . They are even harder to defeat because current counter-measures are not designed to work against this threat. The aim of this project is to examine the vulnerability of laser warning systems against guided weapons, to build an evaluation tool for laser warning sensors (LWS) and seekers, and try to find suitable counter-measures for laser beam-riding missiles that use low power lasers in their guidance systems. The project comes about because of the unexpected results obtained from extensive field trials carried out on various LWRs in the United Arab Emirates desert, where severe weather conditions may be experienced. The objective was to help find a solution for these systems to do their job in protecting the tanks and armoured vehicles crews from such a threat. In order to approach the subject, a computer model has been developed to enable the assessment of all phases of a laser warning receiver and missile seeker. MATLAB & SIMULINK software have been used to build the model. During this process experimentation and field trials have been carried out to verify the reliability of the model. This project will enable both the evaluation and design of any generic laser warning receiver or missile seeker and specific systems if various parameters are known. Moreover, this model will be used as a guide to the development of reliable countermeasures for laser beam-riding missiles.
197

Controle multivariável aplicado a uma coluna de destilação propano-propeno utilizando a técnica de separações de sinais / Multivariable control applied to a distillation column propane-propene utilizing the technique of signal separation.

ALVES, Alain Charles de Melo. 12 April 2018 (has links)
Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-12T14:56:31Z No. of bitstreams: 1 ALAIN CHARLES DE MELO ALVES - DISSERTAÇÃO (PPGEQ) 2017.pdf: 2958576 bytes, checksum: da6d8a9342aea19b0bd4eb2403563d7c (MD5) / Made available in DSpace on 2018-04-12T14:56:31Z (GMT). No. of bitstreams: 1 ALAIN CHARLES DE MELO ALVES - DISSERTAÇÃO (PPGEQ) 2017.pdf: 2958576 bytes, checksum: da6d8a9342aea19b0bd4eb2403563d7c (MD5) Previous issue date: 2017-02-17 / Capes / Os processos indústrias em sua maioria são multivariáveis e apresentam uma grande interação entre suas variáveis. A fim de reduzir essas interações algumas técnicas têm sido desenvolvidas. Análise de Componentes Independentes (ICA) tem sido uma técnica bastante promissora quando se deseja reduzir ou até mesmo eliminar o acoplamento entre as variáveis. Essa técnica é usada na separação de fontes desconhecidas. Embora já existam diversos trabalhos recentes sobre a aplicação do ICA em processos industriais, poucos são voltados para aplicação da técnica em colunas de destilação. Este trabalho estabelece uma estratégia de controle aplicado a uma coluna de destilação de alta pureza com recompressão de vapor utilizando o ICA. Além disso, o trabalho estabeleceu uma estratégia de controle para as composições de base e topo. Para tanto foi feita uma comunicação entre o Aspen Plus DynamicsTM e o Simulink/Matlab®. A comunicação foi estabelecida por meio do bloco AMSimulation. Duas estratégias de controle foram comparadas: MPC com o ICA e MPC sem o ICA. Os resultados da estratégia MPC com ICA se apresentaram mais promissoras mostrando que a técnica ICA é uma ferramenta desacoplante útil para sistemas com forte acoplamento. / The industrial processes are in its majority are multivariable and show a high number of interactions between its variables. Some techniques have been developed to target the reduction of these interactions. Independent Component Analysis (ICA) has been a very promising technique when it is desired to reduce or even eliminate the coupling between variables. The ICA technique has been utilized on the separation of unknown sources. Although there are several different studies targeting the application of ICA in industrial processes, just a few of them geared for technical applications in distillation columns. This dissertation attempts to establish a control strategy applied to a high purity distillation column with vapor recompression using the ICA. In addition, the dissertation proposes to establish a control strategy for the bottom and top of compositions. For this will be a communication between the Aspen Plus DynamicsTM and Simulink / Matlab®. The communication will be established through the AMSimulation block. Two control strategies were compared: MPC with ICA and MPC without MPC. The results of the MPC with ICA strategy were shown to be more promising, showing that the ICA technique is a useful decoupling tool for systems with strong coupling.
198

Control and protection analysis for power distribution in a distributed generation system

Aljadid, Abdolmonem Ibrahim January 2016 (has links)
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology. / Distributed Generation systems based on renewable energy sources, such as wind or solar are mostly intermittent sources, due to their dependency on the weather, whereas those based on other primary energy sources are non-intermittent. All of them are specially designed to be integrated into distribution systems, in order to improve the power demand of consumers. In the last few decades of the twentieth century, several different factors have played a key role in increasing interest in systems. Distributed Generation (DG) is gaining more and more attention worldwide as an alternative to large-scale central generating stations. The aim of this research project is to investigate the contribution of distributed generation in fault current level in a power distribution system. The simulation results indicate that DG can have a positive or negative impact, on the fault current level in distribution network systems. The DG location and size affect the fault level. The second aim of this research was to suggest a model-based method for design, and implementation of a protection scheme for power distribution systems, by establish algorithms in a hardware environment. The overcurrent relay was chosen for the model development because it is considered a simple and popular protection scheme, and it is a common scheme in relaying applications. The proposed relay model was tested for fault conditions applied on a simple power system in different scenarios. The overcurrent relay model was implemented in MATLAB/Simulink, by using MATLAB programming languages and the SimPowerSystem (SPS) Tool. MATLAB/SIMULINK software is applicable to the modelling of generation, transmission, distribution and industrial grids, and the analysis of the interactions of these grids. This software provides a library of standard electrical components or models such as transformers, machines, and transmission lines. Therefore, the modelling and simulations are executed using MATLAB/Simulink version 2014b
199

Design e validação formal de sistemas de controle de voo fly-by-wire

JESUS JUNIOR, Joabe Bezerra de 31 January 2009 (has links)
Made available in DSpace on 2014-06-12T15:56:13Z (GMT). No. of bitstreams: 2 arquivo2770_1.pdf: 3435334 bytes, checksum: c4ebc011cd6476e268421539acd59c8c (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Associação para Promoção da Excelência do Software Brasileiro / O gerenciamento e o projeto de sistemas de engenharia complexos é um desafio interessante. A engenharia de sistemas é um campo interdisciplinar da engenharia focado na melhoria da qualidade de projetos de sistemas. Ela encoraja o uso de métodos e ferramentas como simulação, otimização, análise de confiabilidade e análise estatística para aumentar o conhecimento do sistema, frequentemente representado como um conjunto de modelos. Uma enorme variedade de sistemas dinâmicos precisa ser controlada e pode ser modelada usando os princípios da Teoria de Controle, a base da disciplina de engenharia de controle. Em particular, a engenharia de controle objetiva criar leis de controle para o sistema, que são modeladas usando diagramas de bloco (também chamados de diagramas de leis de controle) e validadas/verificadas usando simulação. Entretanto, a maior parte das validações de leis de controle realizadas na indústria é feita usando ferramentas de simulação como o Simulink, e simulações não cobrem todos os comportamentos do modelo. Além disso, não é fácil modelar uma arquitetura complexa na qual redundância e monitoramento são comumente usados para se obter segurança. Neste trabalho, nós apresentamos três principais contribuições: (1) um conjunto de regras de tradução de modelos Simulink para a algebra de processos CSP (Communicating Sequential Processes), incluindo uma infraestrutura para suportar vários blocos discretos de Simulink; (2) uma estratégia para validar a integração de uma proposta de arquitetura com as leis de controle; e (3) a validação de um sistema de controle de voo dos profundores de um avião produzido pela Embraer. Os resultados mostram que a estratégia pode ser aplicada a modelos complexos através do uso das técnicas formais de abstração de dados e verificação de modelos. Ademais, a estratégia proposta aprimora o processo de desenvolvimento padrão (modelo V) seguido pela indústria por encontrar potenciais defeitos em fases de especificação do projeto, reduzindo tempo de desenvolvimento e custos
200

The vulnerability of laser warning systems against guided weapons based on low power lasers

Al-Jaberi, Mubarak 28 April 2006 (has links)
Laser assisted weapons, such as laser guided bombs, laser guided missiles and laser beam-riding missiles pose a significant threat to military assets in the modern battlefield. Laser beam-riding missiles are particularly hard to detect because they use low power lasers. Most laser warning systems produced so far can not detect laser beam-riding missiles because of their weak emissions which have signals less than 1% of laser range finder power . They are even harder to defeat because current counter-measures are not designed to work against this threat. The aim of this project is to examine the vulnerability of laser warning systems against guided weapons, to build an evaluation tool for laser warning sensors (LWS) and seekers, and try to find suitable counter-measures for laser beam-riding missiles that use low power lasers in their guidance systems. The project comes about because of the unexpected results obtained from extensive field trials carried out on various LWRs in the United Arab Emirates desert, where severe weather conditions may be experienced. The objective was to help find a solution for these systems to do their job in protecting the tanks and armoured vehicles crews from such a threat. In order to approach the subject, a computer model has been developed to enable the assessment of all phases of a laser warning receiver and missile seeker. MATLAB & SIMULINK software have been used to build the model. During this process experimentation and field trials have been carried out to verify the reliability of the model. This project will enable both the evaluation and design of any generic laser warning receiver or missile seeker and specific systems if various parameters are known. Moreover, this model will be used as a guide to the development of reliable countermeasures for laser beam-riding missiles.

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