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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.
31

Caractérisation de matériaux plasmas pour la conception de fonctions hyperfréquences / Characterization of plasma media for the design of hyperfrequency functions

Chruszez, Olivier 04 February 2015 (has links)
Afin de mettre à profit les propriétés des plasmas pour développer des fonctions hyperfréquences originales, le milieu plasma doit d’abord être caractérisé dans cette gamme de fréquence car son expansion et sa densité, supposée homogène, sont des paramètres mal maîtrisés. Une méthode de mesure de la constante diélectrique du plasma a donc été développée pour déterminer une permittivité relative complexe moyenne dans les conditions d’utilisation et d’excitation. A partir d’un modèle basé sur une méthode modale, et de la mesure de fréquence de résonance d’un résonateur, on caractérise un milieu plasma (permittivité, fréquence de coupure plasma) généré au sein d’une ligne microruban multicouches. Cette thèse, à l’intersection entre deux disciplines, plasmas et micro-ondes, valide l’utilisation de plasma localisé au sein d’une technologie planaire multicouches pour dimensionner des lignes d’impédance et/ou longueur de ligne variables. Elle met également en avant les difficultés rencontrées en termes de réalisation, pour générer des plasmas reproductibles et stables. / In order to take profits of the plasma properties to develop new hyperfrequency funtioncs, the plasma media must be first characterize in this frequency range because his expansion and density, supposed homogeneous, are parameters not well known. A method of measurement of the plasma’s dielectric constant have been developped to determine an average relative complexe permittivity in the condition of use and excitation. From this method based on a modal method, and from the measurement of the resonant frequency, we can characterize the plasma media (permittivity, cut-off frequency of the plasma) generated within a multilayer microstrip line. This thesis, which verge on the junction between two major fields : microwaves and plasma physics, allowed us to ascertain on the local use of plasma media within multilayer planar technology, in order to design lines with variable impedance and/or variable electrical length. It also highlights on the major difficulties with the generation of stable and reproductible plasma.
32

Técnicas de reconfigurabilidade dos FPGAs da família APEX 20K - Altera. / Reconfigurability technics for the FPGAs of family APEX 20K - Altera.

Marco Antonio Teixeira 26 August 2002 (has links)
Os dispositivos lógicos programáveis pertencentes à família APEX 20K, são configurados no momento da inicialização do sistema com dados armazenados em dispositivos especificamente desenvolvidos para esse fim. Esta família de FPGAs possui uma interface otimizada, permitindo também que microprocessadores os configure de maneira serial ou paralela, síncrona ou assíncronamente. Depois de configurados, estes FPGAs podem ser reconfigurados em tempo real com novos dados de configuração. A reconfiguração em tempo real conduz a inovadoras aplicações de computação reconfigurável. Os dispositivos de configuração disponíveis comercialmente, limitam-se a configurar os FPGAs apenas no momento da inicialização do sistema e sempre com o mesmo arquivo de configuração. Este trabalho apresenta a implementação de um controlador de configuração capaz de gerenciar a configuração e reconfiguração de múltiplos FPGAs, a partir de vários arquivos distintos de configuração. Todo o projeto é desenvolvido, testado e validado através da ferramenta EDA Quartus™ II, que propicia um ambiente de desenvolvimento integrado de projeto, compilação e síntese lógica, simulação e análise de tempo. / The APEX 20K programmable logic devices family, are configured at system power-up with data stored in a specific serial configuration device. This family of FPGAs contain an optimized interface that permits microprocessors to configure APEX 20K devices serially or in parallel, and synchronously or asynchronously. After configured, it can be reconfigured in-circuit by resetting the device and loading new data. Real-time changes lead to innovative reconfigurable computing applications. The commercial available configuration devices limit to configure the APEX 20K devices only on the system power-up and always with the same configuration data file. This work shows a configuration controller implementation that can manage the configuration and reconfiguration of several FPGAs from multiple configuration files. The entire project is developed, tested and validated through the EDA tool Quartus™ II, that provide a integrated package with HDL and schematic design entry, compilation and logic synthesis, full simulation and worst-case timing analysis.
33

Conception et analyse d'un robot flexible à rigidité active au moyen d'un alliage à mémoire de forme / Design and analysis of a compliant robot with active stiffness by means of shape memory alloy

Mekaouche, Adel 08 March 2016 (has links)
La rigidité est un des objectifs de performance les plus importants pris en compte lors de la conception de systèmes robotiques. Le contrôle de la raideur physique en cours de tâche est une problématique scientifique en plein essor dans le cadre de la conception innovante de robots à forte polyvalence. L’association d’une structure robotique compliante et d’un composant en alliage à mémoire de forme (AMF) est réalisée dans le but d’obtenir des cartes de compliance variables dans le temps sur un même espace de travail. Les AMF sont en effet des matériaux actifs qui possèdent des caractéristiques comportementales pouvant être exploitées dans cette application. La structure considérée pour l’étude n’a pas de degré de liberté interne mais sa déformation permet de créer un pseudo-espace de travail. Celui-ci diffère selon l’état activé/non-activé de l’AMF. L’intersection des deux espaces obtenus représente alors les positions de l’effecteur où il est possible d’avoir des valeurs de compliance différentes. Les cartes obtenues montrent des caractéristiques intéressantes pour la perspective de la conception de robots polyvalents ayant une nouvelle forme de reconfigurabilité basée sur le changement de propriétés matérielles. / The rigidity is one of the most important performance targets which is taken into account for the design of robotic systems. The control of the physical stiffness during industrial tasks is a scientific issue which is rapidly expanding in the context of the innovative design of highly polyvalent robots. The combination of a compliant robotic structure and a shape memory alloy (SMA) component is carried out in the aim of obtaining variable compliance maps over time and in the same workspace. SMAs are actually active materials with specific thermomechanical properties which can be used in this application. The considered structure has no internal degree of freedom, but the deformation of the arms allows the creation of a “Pseudo-Workspace” (PWS). This PWS varies as a function of the activated/non-activated state of the SMA component. The intersection of the two obtained PWSs represents the effector’s positions where it is possible to have different compliance values. Generated maps show interesting characteristics in the perspective of the design of polyvalent robots based on a new type of reconfigurability (change of material properties).
34

Conception et déploiement des Systèmes de Production Reconfigurables et Agiles (SPRA) / Design and deployment of Reconfigurable and Agile Manufacturing Systems (RAMS)

Chalfoun, Imad 26 September 2014 (has links)
L'industrie est aujourd'hui, comme elle a toujours été, une pierre angulaire de l'économie pour chaque pays développé. Avoir une base solide en entreprises industrielles est très important parce qu’elles poussent et stimulent tous les autres secteurs de l'économie, et offrent également une grande variété d'emplois qui apporte des bonnes conditions de vie dans de nombreux secteurs de la société. L’augmentation de la concurrence mondiale, l’évolution rapide du marché, la nécessité de créer des entreprises stables avec des usines rentables obligent la mise en oeuvre d’une démarche globale prenant en compte à la fois les aspects techniques, économiques, logistiques et sociétaux lors de la conception d’un système de production innovant. L’objectif de cette thèse est de contribuer au développement d’un concept innovant de Systèmes de Production Reconfigurables et Agiles (SPRA) permettant de s'adapter rapidement et efficacement aux exigences imposées du marché, des clients, de la technologie des procédés, de l’environnement et de la société afin que l’entreprise soit dynamique, compétitive et rentable. Dans ces travaux de thèse, la proposition d'un modèle générique et la caractérisation de ce nouveau type de système de production ont été décrits en utilisant le langage de modélisation des systèmes complexes (SysML : Systems Modeling Language). Ensuite, nous avons développé un processus de reconfiguration qui représente une démarche à suivre pour concevoir et implanter une nouvelle configuration. De plus, un pilotage opérationnel adapté au SPRA a été introduit. Enfin, quelques travaux développés au cours de cette thèse ont été partiellement déployés sur un démonstrateur industriel au sein de la plate-forme AIP-PRIMECA Auvergne. / Industry is, today as it has always been, a cornerstone of the economy for any developed country. Having a strong manufacturing base is very important because it impels and stimulates all the other sectors of the economy. It provides a wide variety of job, which bring higher standards of living to many sectors of society, and builds a strong middle class. Increasing global competition, rapid changes in the marketplace and the need to create stable companies with profitable plants require the implementation of a global approach, taking into account technical, economic, logistic and societal aspects in the design of an innovative manufacturing system. The aim of this dissertation is to contribute to the development of an innovative concept of Reconfigurable and Agile Manufacturing Systems (RAMS) to adapt quickly and effectively to the requirements imposed by markets, customers, technology processes, the environment and society, to ensure that the enterprise is dynamic, competitive and profitable. In this thesis work, the characterization and proposal of a generic model for this new type of manufacturing system have been described using the language of complex systems modeling (SysML: Systems Modeling Language). We have developed a reconfiguration process that represents the approach to follow in the design and implementation of a new configuration. In addition, the operational control of a RAMS has been introduced. Finally, some works developed in this thesis have been partially deployed on an industrial demonstrator within the AIP-PRIMECA Auvergne organisation.
35

Novel Reconfigurable Folded-Slot Antenna Application

Zhao, Jincheng 15 June 2020 (has links)
No description available.
36

Increasing process reconfigurability and quality in HMLV assembly lines using Industry 4.0 : A case study in the automotive industry / Ökning av rekonfigurerbarhet och kvalitet i processer hos HMLV-monteringslinor genom Industri 4.0 : En fallstudie inom fordonsindustrin

Bazarkhuu, Dagvadorj, Dannert, Evelina January 2023 (has links)
The automotive industry is responsible for substantial emissions and is therefore transitioning to the new market of electromobility. With changing market conditions and uncertain demand, frequent product launches and customization are increasingly common. Responsiveness has also gained importance, which is why one way to manage the constant change is to use High-Mix-Low-Volume (HMLV) assembly lines. These produce multiple products but at lower volumes, and are characterized by their reconfigurability, i.e., capability to adapt their capacity as well as functionality. The HMLV assembly lines often have high product and process complexity. As a result, standardization and automation of the processes become difficult to realize. Instead, they are dependent on multi-skilled operators and flexible equipment to ensure high quality. Still, the industry continues progressing towards automation and connectivity. Industry 4.0 may facilitate this objective, as well as enhanced reconfigurability and quality in assembly, but despite the increasing interest in the field on Industry 4.0 and related concepts, there is limited research on its potential application for HMLV assembly lines. This report therefore studies the potential of Industry 4.0 to be implemented as a way to combine the strive for increased digitalization with the demand for customization and responsiveness. More specifically, the aim was to provide insights on how Industry 4.0 can improve process reconfigurability and quality in HMLV assembly lines, and to investigate the enablers and barriers to its implementation. To do this, a semi-structured literature review and a multi-case study were conducted. In total, six cases of varying characteristics were investigated through a series of unstructured and semi-structured interviews, site visits and direct observations. Industry 4.0 is built on Cyber-Physical Systems (CPS), which revolves around the integration of physical and digital assets in the manufacturing process. It was found that Industry 4.0 components could improve the reconfigurability and quality at HMLV assembly lines. The literature review presented a framework consisting of six features of reconfigurability: modularity, customization, scalability, convertibility, integrability and diagnosability. Most of these could directly or indirectly be enhanced by Industry 4.0 applications. For example, standardized interfaces in hardware and software were deemed essential for integrability. Mobile modular workstations such as AGVs (Automated Guided Vehicles) were examples of a key asset for scalability and convertibility. Availability, accessibility, and accuracy in data from operations, and effective analytics of the data, could improve modularity and customization. It could also improve diagnosability through predictive maintenance. Connectivity was a prerequisite for systematic data management which could also positively impact the quality. Data enabled a better understanding of processes and was the first step towards improvement. Having real-time data and visualizing it could lead to optimized planning and to addressing issues such as deviations close to the source. Another technology which could improve quality was for example augmented reality for operator training. Several enablers and barriers for Industry 4.0 implementation were identified. The most important enablers were the current paradigm shift towards digitalization, the alignment with agile working ways, collaboration between IT (agile) and production (waterfall/lean), and the synergy between reconfigurable systems and Industry 4.0 implementation. The most prevalent barriers were the lack of IT resources in production, legacy systems and equipment with established ways of working, and the integration of a segregated portfolio of systems. Finally, a recommendation is that all parts of the production system should be reconfigurable: equipment, systems and operators, and the way of working should be compatible with the philosophy. / Fordonsindustrin står för omfattande utsläpp och genomgår därför en övergång till den nya marknaden e-mobilitet. Med förändrande marknadsvillkor och osäker efterfrågan är frekventa produktlanseringar och specialanpassade produkter vanligt förekommande. Responsivitet har också blivit allt viktigare, varför en vanlig lösning för att möta konstant förändring är genom användandet av monteringslinor med hög mix och låg volym (HMLV). Dessa linor producerar flera olika produkter av lägre volym och karaktäriseras av sin rekonfigurerbarhet, det vill säga deras förmåga att anpassa sin kapacitet såväl som funktionalitet. Denna typ av monteringslinor har ofta hög produkt- och processkomplexitet vilket resulterar i att standardisering och automation av processerna blir svårt att realisera. Istället är de beroende av skickliga operatörer samt flexibel utrustning för att säkerställa hög kvalitet. Trenden är dock att industrin går mot högre nivåer av automation och uppkoppling. Industri 4.0 skulle kunna möjliggöra dessa mål, samt bidra till ökad rekonfigurerbarhet och kvalitet i montering, men trots det ökande intresset inom området Industri 4.0 och relaterade koncept är forskningen gällande dess potentiella tillämpning i HMLV monteringslinor begränsad. Denna rapport studerar därför potentialen för Industri 4.0 att tillämpas som ett sätt att kombinera strävan mot digitalisering med efterfrågan av specialanpassade produkter och responsivitet. Mer specifikt ämnar rapporten ge inblick i hur Industri 4.0 kan förbättra rekonfigurerbarheten och kvaliteten i monteringslinor med hög mix och låg volym, och att utreda både möjliggörande och hindrande faktorer för dess implementering. Metoden som använts för att göra detta har varit en semistrukturerad litteraturstudie samt en flerfallsstudie. Totalt studerades sex fall genom en serie ostrukturerade och semistrukturerade intervjuer, studiebesök och observationer. Industri 4.0 bygger på principen om cyberfysiska system, vilket handlar om integration av fysiska och digitala komponenter i tillverkningsprocessen. Det visade sig att komponenter av Industri 4.0 på flera sätt kan förbättra rekonfigurerbarhet och kvalitet för HMLV monteringslinor. Litteraturstudien presenterade ett ramverk bestående av sex egenskaper för att uppnå rekonfigurerbarhet. Dessa var: modularitet, specialanpassning, skalbarhet, konverterbarhet, integrerbarhet och diagnostiserbarhet. Majoriteten av dessa kunde direkt eller indirekt främjas med hjälp av Industri 4.0-applikationer. Exempelvis bedömdes standardiserade gränssnitt i hård- och mjukvara vara väsentligt för integrerbarhet. Mobila, modulära arbetsstationer såsom AGVer (Automatic Guided Vehicles) var exempel på en nyckeltillgång för skalbarhet och konverterbarhet. Tillgång till giltig data och effektiv analys av datan kunde förbättra modularitet och specialanpassning. Det kunde också förbättra diagnostiserbarheten genom proaktivt underhållsarbete av maskiner. Uppkoppling sågs som en förutsättning för systematisk datahantering vilket också kunde ha en positiv inverkan på kvaliteten. Data möjliggjorde ökad förståelse för processer och var därmed ett första steg mot förbättringar. Med hjälp av realtidsdata och visualisering av denna kunde planering optimeras och avvikelser adresseras nära källan. Ytterligare teknik som kunde förbättra kvalitet var exempelvis augmented reality (AR) för effektiv träning av operatörer. Ett flertal möjliggörande och hindrande faktorer för tillämpning av Industri 4.0 identifierades. De viktigaste möjliggörarna var den rådande digitaliseringen, samarbete mellan IT (agilt) och produktion (waterfall/lean), synergier mellan rekonfigurerbara system och Industri 4.0-implementering samt mellan Industri 4.0 och agila arbetssätt. De viktigaste barriärerna var brist på IT-resurser i produktion, utdaterade system och utrustning, samt integreringen mellan en uppsjö av skilda system. Slutligen presenterades rekommendationer, varav ett centralt råd var att alla delar av ett produktionssystem, det vill säga utrustning, system och operatörer, bör göras rekonfigurerbara.
37

On circularity in production systems : Exploring the realization through circularity practices

Skärin, Filip January 2023 (has links)
The manufacturing industry stands in front of huge challenges. Negative environmental impacts must be drastically reduced and new sustainable products must be introduced at an accelerating pace. Coping with these challenges are significant in order to deal with the increasingly emerging climate crisis. To slow down the climate crisis, the approach of circularity wherein the utilization and lifetimes of resources and materials are maximised with the aim to achieve a near perpetual closed material loop has gained a significant increase in attention. However, most research within circularity has emphasised on the product, especially practices occurring after being produced. A seldomly studied perspective involves exploring the realization of circularity within the production system. A clear description is lacking regarding what circularity in production systems actually constitutes of, and how this can be realized. Therefore, the purpose of this thesis is to expand the knowledge regarding the realization of circularity in production systems. To fulfil the purpose, this research was initiated by a literature review and a document study, which were conducted in order to describe which circularity practices exist in production systems, both form an academic and practical point of view. Subsequently were workshops with industrial experts within production systems held in order to identify challenges with realizing circularity in production systems. The literature review, document study, and workshops laid the foundation for support development, which was the final phase in the thesis. This included supporting the longevity of production systems by adopting circularity theories to cover production system, as well as investigating how to analyse and evaluate circularity in production systems. The results from this were incorporated in a conceptual framework for circular production systems and in a tool for rapid assessment of circularity in production systems. / Tillverkningsindustrin står inför enorma utmaningar. Miljöpåverkan måste drastiskt minska och nya hållbara produkter måste introduceras i allt snabbare takt. Att hantera dessa utmaningar är betydande för att hantera den alltmer framväxande klimatkrisen. För att bromsa klimatkrisen har cirkularitet, där utnyttjandet och livslängden för resurser och material maximeras med målet att uppnå en nästan evig sluten materialslinga, fått en betydande uppmärksamhet. Hittills har forskning inom cirkularitet fokuserat på produkterna som tillverkas, framför allt under användningen av produkten. Ett sällan studerat perspektiv innebär att undersöka hur cirkularitet i produktionssystem kan uppnås. En tydlig beskrivning saknas gällande vad cirkularitet i produktionssystem egentligen innebär och hur detta kan realiseras. Därför är syftet med denna avhandling att utöka kunskapen om realiseringen av cirkularitet i produktionssystem. För att uppfylla syftet initierades denna forskning av en litteraturgenomgång och en dokumentstudie. Dessa genomfördes för att beskriva arbetssätt kopplat till realiseringen av cirkularitet inom produktionssystem, både från en akademisk och praktisk ståndpunkt. Vidare hölls även workshops med experter inom produktionssystem för att identifiera utmaningar med att uppnå cirkularitet inom produktionssystem. Litteraturgenomgången, dokumentstudien och workshops lade grunden för stödutveckling, som var den sista fasen i avhandlingen. Denna inkluderade att stödja produktionssystemens livslängd genom att anpassa existerande teorier om cirkularitet till produktionssystem, samt att undersöka hur man analyserar och utvärderar cirkularitet i produktionssystem. Resultaten från detta införlivades i ett konceptuellt ramverk för cirkulära produktionssystem och i ett verktyg för snabb utvärdering av cirkularitet i produktionssystem.
38

Design and Implementation of Reconfigurable and MIMO Antennas for Future Heterogeneous Wireless Systems

Mshwat, Widad F.A.G.A. January 2022 (has links)
Libyan Ministry of Higher Education. / The full text will be available at the end of the embargo: 28th Nov 2024 / Subtitle: Simulation and Measurement of Reconfigurable Antennas for Cognitive Radio, UWB Applications, Investigation of Antenna Gain and Efficiency, Frequency Tuneable Range, Antenna Radiation Performance and Antenna Design Optimization using Parametric Studies as well as using MIMO antenna for wireless body area networks
39

Interface radio IR-UWB reconfigurable pour les réseaux de microsystèmes communicants / Reconfigurable IR-UWB radio interface for wireless sensor networks

Lecointre, Aubin 01 October 2010 (has links)
Les travaux présentés lors de cette thèse s’inscrivent dans le cadre des réseaux de microsystèmes communicants dont les réseaux de capteurs sont l’exemple le plus connu. La problématique adressée est la conception d’une interface radio communicante répondant aux besoins spécifiques des microsystèmes communicants : simplicité, faible coût, faible consommation, faible encombrement, haut débit et reconfigurabilité. Les technologies actuelles sans fil comme le WiFi, le Bluetooth, et Zigbee ne sont pas en mesure de répondre à ces contraintes spécifiques. L’étude se focalise sur la technologie IR-UWB (Impulse Radio Ultra-WideBand). Dans un premier temps, une étude conjointe sur la capacité du canal et l’implémentation matérielle est menée pour déterminer l’architecture optimale des émetteurs-récepteurs en IR-UWB. Cette étude propose l’utilisation d’une architecture multi bandes IR-UWB (MB-IR-UWB) à implémentation mixte à 60 GHz avec des antennes directives. Cette solution est optimisée sur les critères de débit et puissance consommée. Afin de supporter l’ensemble des besoins des applications des réseaux de microsystèmes communicants et l’évolution de l’environnement d’opération, la reconfigurabilité doit être implémentée dans les émetteur-récepteurs proposés. Ces travaux présentent une proposition de reconfigurabilité par paramètres, qui permet de supporter la plus grande gamme de reconfigurabilités multi propriétés (débit, taux d’erreur, portée, puissance consommée, …) de l’état de l’art. Enfin, pour valider par la mesure les travaux sur la reconfigurabilité et sur les architectures d’émetteur-récepteurs IR-UWB, des implémentations FPGA et ASIC sont réalisées. Un nouveau procédé de synchronisation et démodulation conjointe reconfigurable est proposé dans le récepteur IR-UWB BPSK S-Rake. Les mesures montrent que le circuit de traitement proposé améliore les performances en synchronisation, démodulation, efficacité, débit du réseau, consommation et complexité du circuit. L’émetteur-récepteur IR-UWB reconfigurable proposé atteint un débit et une gamme de reconfigurabilité supérieure à l’état de l’art. / The research work presented in this thesis is situated in the framework of wireless sensor networks (WSNs). The issue addressed is the design of a radio interface answering the specific needs of WSNs: simplicity, low cost, low power, small size, high data rate and reconfigurability. Current wireless technologies like WiFi, Bluetooth, and Zigbee are not able to respond to these requirements. Thus this study focuses on Impulse Radio Ultra-WideBand (IR-UWB) technology. At first, a joint study of the channel capacity and the hardware implementation is carried out to determine the optimal architecture of IR-UWB transceivers. This study proposes an architecture using multi-band IR-UWB (MB-UWB-IR) with a mixed implementation at 60 GHz with directional antennas. This solution is optimized according to the criteria of data rate and power consumption. To support the all the needs of WSN applications and to adapt to the evolution of the WSN’s environment, reconfigurability must be implemented in the proposed IR-UWB transceiver. This thesis presents a new solution: the reconfigurability by parameters. It supports the widest range of multi-property reconfigurability (with respect to data rate, bit error rate, radio range, power consumption, ...) of the state of the art. Finally, to validate these techniques by measurements, FPGA and ASIC implementations are realized by using the reconfigurability and the IR-UWB transceiver architecture proposed. A new method for joint synchronization and demodulation is proposed for a reconfigurable IR-UWB BPSK S-Rake receiver. The measurements show that the proposed technique improves the circuit performance: synchronization, demodulation, efficiency, network throughput, power consumption and complexity of the circuit. The proposed IR-UWB reconfigurable transceiver achieves a data rate and a wider range of reconfigurability compared to the state of the art
40

Design of Ultra-Compact and Low-Power sub-10 Nanometer Logic Circuits with Schottky Barrier Contacts and Gate Work-Function Engineering

Canan, Talha Furkan 23 May 2022 (has links)
No description available.

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