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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.
11

Modelación y Simulación de DSP TI TMS320C55 Genérico

Brugnoli González, Sebastián January 2009 (has links)
No autorizada por el autor para ser publicada a texto completo / Este proyecto consiste en la modelación e implementación de un simulador de conjunto de instrucciones, funcional atemporal, de la unidad de procesamiento de un DSP Texas Instruments TMS320C55. Este simulador tiene por objetivo proveer de una herramienta de desarrollo de software independiente del diseño y elaboración del hardware, para no retrasar la primera por la indisponibilidad del último. Importante es que el usuario tenga una experiencia, en cuanto a capacidades y tiempos de respuesta, lo más cercana al producto final. Esto se logra mediante la abstracción de las características irrelevantes del hardware y emulación de lo mínimo necesario para la correcta operación del software. Para desarrollar este simulador se utiliza la herramienta ArchC en conjunto con la documentación técnica del DSP. Considerando las características de estos, se realiza una evaluación sobre que elementos del DSP es necesario, factible y prioritario implementar en el marco de tiempo. Durante el trascurso del proyecto, para verificar que cada instrucción opere acorde a lo especificado por la documentación oficial, se somete cada una de estas a pequeñas pruebas, cuyos resultados son contrastados con los ejemplos encontrados en la especificación de cada instrucción. Así, en este caso particular se obtuvo como resultado un simulador con un soporte parcial del total del ISA pero que abarca un gran número de funcionalidades. Este ha sido evaluado mediante la verificación de sus operaciones en valor y modificación del estado. En términos concretos esto se traduce en 115 instrucciones implementadas, de las cuales 78 pasan exitosamente todas las pruebas. Adicionalmente, el código y sus métodos se han estructurado de tal forma que la definición de nuevas instrucciones se pueda realizar mediante la concatenación simple de métodos y se han dejado programadas una serie de funciones que abarcan la gran mayoría de operaciones definidas en el hardware, dejando una base solida para trabajos futuros. En conclusión, se tienen dos aportes en este trabajo: una metodología para la abstracción de hardware y un simulador de conjunto de instrucciones, funcional atemporal, operativo. Estos dan pie para futuros trabajos en el perfeccionamiento del propio proyecto o en trabajos análogos en las áreas de electrónica digital y desarrollo de software.
12

Phlebitis Rates in Trauma Patients: Peripheral Intravenous Catheters Started In or Outside the Emergency Department

Zarate, Ligia J. 17 July 2007 (has links)
Ligia J. Zarate College of Nursing Master of Science Peripheral catheter-related phlebitis is the inflammation of a superficial vein that can lead to infection or thrombus formation if untreated. About 150 million peripheral intravenous catheters (PIVC) are inserted in the United States each year with phlebitis rates reported between 5% and 70%. Many PIVCs are started on trauma patients, but the rate of phlebitis in trauma patients whether the PIVC is started outside the emergency department (ED) or inside the ED is unknown. Therefore, the purpose of this pilot study was to determine phlebitis rates in trauma patients when PIVC's are started inside or outside the emergency department. Variables investigated, which may influence phlebitis rates were duration of time the catheter was in place, the anatomical placement site of the PIVC, the catheter gauge, where the PIVC initially was placed (inside or outside the ED), and the injury severity score (ISS). This was a prospective descriptive design. Results indicated 432 catheters were placed inside or outside the ED in trauma patients that met the inclusion criteria. The overall phlebitis rate was 5.79 %. The rate of phlebitis when the PIVC was started inside the ED was 2.92%. The rate of phlebitis when the PIVC was started outside the ED was 6.94%. If the PIVC was started outside the ED by EMTs the rate was 6.09%. When the PIVC was started outside the ED by paramedics the rate was 7.78%. There was no significant difference in rates of phlebitis according to where the PIVC was started when a Chi Square analysis was performed. No variables predicted phlebitis no matter where the PIVC was started when regression analyses were conducted. The rate of phlebitis in PIVCs started in the ED, or by EMTs or Paramedics outside the ED in this study was similar to and low according to the literature. The Center for Disease Control and Prevention (CDC) suggests removal of the PIVC within 48 hours if placed under emergency situations. However in this study, phlebitis rates of trauma patients meet the benchmark of best practice and perhaps removal of the PIVC within 48 hours should be reconsidered. Complete documentation of medical records was 87.4%. However, best practice of recording information and patient response to treatment should be higher.
13

Distribution and Transportation of Sand and Potential Sand Source Materials on Titan: Implications for the Geologic History

Lake, Benjamin Dean 09 August 2022 (has links)
Titan is an important planetary body for aeolian research because of the vast equatorial sand seas that span 20% of its surface. Previous studies have determined the general margins of sand and sand seas on Titan, and have speculated about the source of Titan's sand. Little research has been done concerning where sand collects in the sand seas. Additionally, the relationships be-tween material distributions as observed by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) and the history of erosion and transportation of sediments across equatorial latitudes is not fully understood. This work focuses on an in depth evaluation of sand distribution and abundance across the sand seas, and presents evidence for an alternative sand source. This work also addresses a potential stratigraphy for the equatorial regions based on the excavation of materials from impact craters. We mapped the extent of relative sand abundances by comparing different Cassini image datasets, largely by mapping where the Imaging Science Subsystems (ISS) regions were darkest, in-dicating the presence of more sand. Our results revealed that greater abundances of sand accumu-late near the eastern margins of sand seas. This is in agreement with previous studies that demon-strated general W to E transport, and fits a general model of sand transport across the sand seas to collect at the downwind margins, perhaps ahead of topographic obstacles that mark the eastern ends of the sand seas. Additionally, we found that the largest continuous expanse of abundant sand de-posits lie across Belet, a large sand sea that occupies a broad equatorial lowland. Another sand sea of interest is Shangri-La, which has a recessed SE margin adjacent to the broad, albedo-bright de-pression Xanadu. We also found abundant sand deposits within Shangri-La across a corridor be-tween highlands and along the SE boundary of the sand sea. Dune crest orientations across eastern Shangri-La indicate WNW to ESE transport in the region. We propose that the low topography of Xanadu, coupled with the strong gradient in albedo between Shangri-La and Xanadu would gener-ate atmospheric disturbances similar to those responsible for transporting sand across positive changes in elevation on Mars, and may be responsible for the distinct boundary. VIMS-blue materials are generally associated with water ice mixed with organic com-pounds. We found that VIMS-blue surfaces across equatorial latitudes tend to be directly adjacent to and upwind of sand seas. This, coupled with geomorphological observations of erosional charac-teristics and examination of material properties, suggests that sand could at least in part be derived from VIMS-blue materials. We propose 3 environments (alluvial fans, dry lakebeds, and ejecta from impact craters) for sand production using this interpretation and making comparisons with SAR, ISS, and VIMS imagery. Modeling suggests that Titan's lithosphere significantly thickened 500 m.y. ago. We inter-pret an elongate exposure of VIMS-blue materials adjacent to Aztlan to be a rift caused by a thick-ening of the lithosphere, similar to many of the other icy bodies of the solar system. Our interpreta-tion is further supported by the distribution of cryovolcanic features alongside the proposed rift. Anomalous VIMS-blue and bright regions within eastern Xanadu are distributed in a pattern that resembles a multi-ringed impact basin. Additionally, when a value threshold was applied to ISS imagery, a bright circular feature was revealed within western Xanadu. These observations suggest two large impacts may have been significantly responsible for creating Xanadu. Comparisons of impact crater models with VIMS imagery of Paxsi, Menrva, Sinlap, Selk, and other craters suggest alternating layers of VIMS-bright and VIMS-blue cover much of the equatorial latitudes of Titan. We completed ground penetrating radar (GPR) and global positioning system (GPS) surveys across margins of the Kelso Dunes to evaluate the effects of fluvial interaction on sand depth. Our terres-trial model was compared to sand seas on Titan that appear to also have interactions with fluvial channels. Distributions of sand suggest that in both the Kelso Dunes and on Titan, fluvial obstruc-tion is temporary and on Titan isolated across small regions. This work leads to a better understanding of sand production, accumulation and transport on Titan and in sand seas in general, and reveals a basic stratigraphy of the equatorial regions of Titan. This region is of particular interest because it is the landing site of the Dragonfly mission, now in design.
14

Outils ensemblistes d'analyse et de synthèse des lois de commande robustes pour des systèmes incertains. / Invariant sets techniques for analysis and synthesis of robust control laws for uncertain systems

Luca, Anamaria 26 September 2011 (has links)
Le travail de recherche concrétisé par ce mémoire de thèse se trouve à l’intersection de deux domaines importants, la commande robuste des systèmes linéaires (LTI, LPV, en commutation) à temps discret affectés par des perturbations permanentes bornées et des contraintes et les ensembles invariants ellipsoïdaux maximal ou minimal. La première partie de ce mémoire se focalise sur l’analyse de la stabilité entrée-état (en anglais ISS) du système par rapport à une perturbation bornée et le calcul des ensembles invariants ellipsoïdaux minimal ou maximal (ou sous forme d’ellipsoïdes tronqués) satisfaisant les contraintes. La deuxième partie envisage la synthèse d’une commande par retour d’état ISS stable et robuste vis-à-vis de perturbations bornées, garantissant l’ellipsoïde invariant maximal satisfaisant les contraintes ; puis la synthèse d’une loi decommande par retour d’état et observateur ISS stable vis-à-vis de perturbations bornées, garantissant une certaine performance ; enfin la synthèse d’un paramètre de Youla afin de garantir la projection maximale sur le sous-espace de l’état initial. La projection obtenue possède alors un volume plus grand que celui obtenu sans le paramètre de Youla d’où une amélioration en termes de robustesse. Une dernière étape vise à obtenirun compromis entre la robustesse et la performance en utilisant des critères basés sur le placement de pôles ou sur la vitesse de décroissance de la fonction de Lyapunov. Tous les résultats théoriques obtenus sont exprimés sous forme d’inégalités matricielles et sont validés en simulation et de façon expérimentale dans le cadre de la commande d’un convertisseur de puissance. / The research concretized in this memory is located at the intersection of two important fields, the robust control of discrete-time linear systems (LTI, LPV, switched) affected by bounded disturbances and constraints and the ellipsoidal invariant sets theory.The first part of this memory focuses on the analysis of input-to-state stability (ISS) over a bounded perturbation and the computation of the maximal or minimal invariant ellipsoidal (or truncated ellipsoidal) set satisfying the constraints. The second part is considering the synthesis of a control state feedback law ISS stable and robust over bounded disturbances, ensuring the maximal ellipsoidal invariant set satisfying the constraints, then the synthesis of an observer-based control law ISS stable over bounded disturbances,ensuring a certain performance, and finally the design of a Youla parameter guaranteeing the maximal ellipsoidal projection on the initial state subspace. The resulting projection has a volume greater than the one obtained without the Youla parameter resulting an improvement in terms of robustness. A final step is to obtain a compromise between robustness and performance using criteria based on poles placement or on theLyapunov function decreasing rate. The theoretical results are expressed as matrix inequalities and are validated in simulation and and experimentally on a Buck DC-DC converter.
15

Exploring Megaproject Governance with Regard to Collaboration : The case of the International Space Station / Utforska megaprojektstyrning med hänsyn till samarbete : Fallet med den internationella rymdstationen

Gabor, Tatar January 2021 (has links)
Our society is more dependent on global problem-solving than ever before. Megaprojects are one way of solving this challenge. Even though some of them are supposed to give answers to the direst problems of our time, our knowledge about them is paradoxically poor that leads to economic losses. The areas that especially demand attention are the project architecture, relationships, and innovative governance solutions that promote collaboration. The purpose of the thesis is to explore how megaprojects are governed in regard to collaboration through the case of a science-focused intergovernmental megaproject. The report builds an understanding of megaprojects, governance, and collaboration. Then it attempts to identify how governance affects collaboration over the paradox of control and flexibility within the case of the International Space Station (ISS) as one of the most recognized examples of megaprojects. It has been found that contractual and relational governance should be both present within megaproject governance. Because historically contractual arrangements are dominating governance, additional focus is required on the relational counterpart. The five main parts of the ISS governance, legal framework, organizational structure, goals, roles, and funding system, are mainly related to contractual governance, facilitating control. However, they also feature mechanisms that promote flexibility, thus providing a platform for collaborative practices to be formed. The top tier of the legal framework provides stability but the lower tiers offer opportunities to implement changes in the program. The goals of the ISS serve as a strong motivator that puts the common goals in front of the individual agendas of the partner countries. Furthermore, concerning funding, the in-kind contributions system provides a different set of incentives through bartering, compared to the traditionally used financing, and supports the collaborative environment by building closer relationships with industry partners. The example of the ISS revealed valuable lessons to better understand intergovernmental megaprojects and solve the challenges of the future affecting us. / Vårt samhälle är mer beroende av problemlösning på en globalnivå där specifikt Megaprojekt är en form för att lösa denna utmaning. Även om vissa av dem ska ge svar på de allvarligaste problemen i vår tid, är vår kunskap om dem paradoxalt dålig vilket leder till ekonomiska förluster. De områden som särskilt kräver uppmärksamhet är projektarkitekturen, relationer och innovativa styrningslösningar som främjar samarbete. Syftet med denna masteruppsats är att undersöka hur megaprojekt styrs gällande samarbetet mellan vetenskapligt fokuserat mellanstatliga projekt. Uppsatsen skapar en ökad förståelse av megaprojekt, styrning och samarbete. Därefter identifieras hur styrning påverkar samarbetet över motsägelserna mellan kontroll och flexibilitet inom den International Space Station (ISS). ISS är ett av de mest erkända exemplen på megaprojekt. Man har funnit att både avtals- och relationell styrning bör vara närvarande inom megaprojektstyrning. Eftersom historiskt avtalsmässiga arrangemang är dominansstyrning krävs mer fokus på den relationella motsvarigheten. Den fem huvuddelarna av ISS styrning, rättsligt ramverk, organisationsstruktur, mål, roller och finansieringssystem är huvudsakligen relaterade till avtalsstyrning vilket underlättar kontroll. Delarna visas även ha mekanismer som främjar flexibilitet vilket skapar en plattform för kommande samarbetsmetoder. Den högsta nivån i den rättsliga ramen ger stabilitet medan de lägre nivåerna främjar möjligheter att genomföra förändringar i programmet. Målen med ISS fungerar som en stark motivator som sätter de gemensamma målen framför partnerländernas individuella dagordningar. Gällande finansiering tillhandahåller systemet med naturbidrag genom byteshandel en annan uppsättning incitament jämfört med den traditionellt använda finansieringen och stöder vidare samarbetsmiljön genom att bygga närmare relationer med industripartners. Exemplet på ISS avslöjade värdefulla lärdomar för att bättre förstå mellanstatliga megaprojekt och lösa framtidens utmaningar som påverkar oss.
16

O critério material da hipótese de incidência do imposto sobre serviços / The Cof the hypothesis of tax incidence over services

Dacomo, Natalia De Nardi 11 April 2005 (has links)
Made available in DSpace on 2016-04-26T20:25:11Z (GMT). No. of bitstreams: 1 iss2005.pdf: 1124516 bytes, checksum: 715c2432b36d257eab548dc7aea4adde (MD5) Previous issue date: 2005-04-11 / The present paper aims to construct the sense and the reach of the material criterion of the hypothesis of tax incidence over services, established by the constitutional competence norm, comparing the concept of services rendered and the infra-constitutional legislation. We must emphasize that the material criterion of the tax incidence of hypothesis over services involves both the concept of services rendered and the services list function and that both have been an object of controversy between legal doctrine and jurisprudence. In view of this, we have proposed the adoption of a new concept of service rendered: the logical-semantic, where to render service is the legal relation that has as aim the action or the effect of serve, provide, give, concede, excuse, give oneself something in activity form, to execute an intellectual work or material construction. Regarding the services list, we have elaborated the comprehension that its function is to establish the criteria so that the events of the real world can be identified by law operators as legal facts. As it composes the incidence hypothesis of an abstract and general norm, the list describes the criteria to the identification of a fact, in other words, connotative. To realize the proposed task on a scientific way, we have started from the analysis of law general categories, stipulating the comprehension of relevant subjects to investigation, as the concepts of Science of Law, positive law, legal system, legal norm and tributary incidence. We have elected the semiotics as theoretical instrument to realize the logical-semantic and pragmatic analysis of the concept of services rendered, list services function and the items described by this list. Finally, we have established the material criterion of the hypothesis of tax incidence as being the legal relation to render services described by the services list introduced on legal ordinance by the Complementary law n. 116/03. / O presente trabalho tem por objetivo construir o sentido e o alcance do critério material da hipótese de incidência do imposto sobre serviços, estabelecido pela norma de competência constitucional, cotejando o conceito de prestação de serviços e a legislação infraconstitucional. Convém ressaltar que o critério material da hipótese de incidência do imposto sobre serviços envolve tanto o conceito de prestação de serviços quanto a função da lista de serviços e que ambos têm sido objeto de polêmica entre a doutrina jurídica e a jurisprudência. Em vista disso propomos a adoção de um novo conceito de prestação de serviço: o lógico semântico, segundo o qual prestar serviços é a relação jurídica que tem como objeto a ação ou o efeito de servir, propiciar, dar, conceder, dispensar, dar de si algo em forma de atividade, executar trabalho intelectual ou obra material. Quanto à lista de serviços, elaboramos o entendimento de que sua função é a de estabelecer os critérios para que os eventos do mundo real possam ser identificados pelos operadores do direito como fatos jurídicos. Na medida em que compõe a hipótese de incidência de uma norma geral e abstrata, a lista descreve critérios para identificação de um fato, ou seja, é conotativa. Para que a tarefa proposta pudesse ser realizada de modo científico, partimos da análise das categorias gerais do direito, estipulando o entendimento sobre temas relevantes para a investigação como os conceitos de Ciência do Direito, direito positivo, sistema jurídico, norma jurídica e incidência tributária. Elegemos a semiótica como instrumental teórico para realizar a análise lógico-semântica e pragmática do conceito de prestação de serviços, da função da lista de serviços e dos itens descritos por essa lista. Finalmente, estabelecemos o critério material da hipótese de incidência tributária como sendo a relação jurídica de prestar serviços descrita pela lista de serviços introduzida no ordenamento
17

Applications of information sharing for code generation in process virtual machines

Kyle, Stephen Christopher January 2016 (has links)
As the backbone of many computing environments today, it is important that process virtual machines be both performant and robust in mobile, personal desktop, and enterprise applications. This thesis focusses on code generation within these virtual machines, particularly addressing situations where redundant work is being performed. The goal is to exploit information sharing in order to improve the performance and robustness of virtual machines that are accelerated by native code generation. First, the thesis investigates the potential to share generated code between multiple threads in a dynamic binary translator used to perform instruction set simulation. This is done through a code generation design that allows native code to be executed by any simulated core and adding a mechanism to share native code regions between threads. This is shown to improve the average performance of multi-threaded benchmarks by 1.4x when simulating 128 cores on a quad-core host machine. Secondly, the ahead-of-time code generation system used for executing Android applications is improved through the use of profiling. The thesis investigates the potential for profiles produced by individual users of applications to be shared and merged together to produce a generic profile that still provides a lot of benefit for a new user who is then able to skip the expensive profiling phase. These profiles can not only be used for selective compilation to reduce code-size and installation time, but can also be used for focussed optimisation on vital code regions of an application in order to improve overall performance. With selective compilation applied to a set of popular Android applications, code-size can be reduced by 49.9% on average, while installation time can be reduced by 31.8%, with only an average 8.5% increase in the amount of sequential runtime required to execute the collected profiles. The thesis also shows that, among the tested users, the use of a crowd-sourced and merged profile does not significantly affect their estimated performance loss from selective compilation (0.90x-0.92x) in comparison to when they they perform selective compilation with their own unique profile (0.93x). Furthermore, by proposing a new, more powerful code generator for Android’s virtual machine, these same profiles can be used to perform focussed optimisation, which preliminary results show to increase runtime performance across a set of common Android benchmarks by 1.46x-10.83x. Finally, in such a situation where a new code generator is being added to a virtual machine, it is also important to test the code generator for correctness and robustness. The methods of execution of a virtual machine, such as interpreters and code generators, must share a set of semantics about how programs must be executed, and this can be exploited in order to improve testing. This is done through the application of domain-aware binary fuzzing and differential testing within Android’s virtual machine. The thesis highlights a series of actual code generation and verification bugs that were found in Android’s virtual machine using this testing methodology, as well as comparing the proposed approach to other state-of-the-art fuzzing techniques.
18

Coordinated Control of Marine Craft

Ihle, Ivar-Andre Flakstad January 2006 (has links)
<p>This thesis contains new results on the problem of coordinating a group of vehicles. The main motivation driving this work is the development of control laws that steer individual members of a formation, such that desired group behavior emerges. Special attention is paid to analysis of coordination issues, in particular formation control of marine craft where robustness to unknown environmental forces is important. Coordinated control applications for marine craft include: underway replenishment, maintaining a formation for increased safety during travel and instrument resolution, and cooperative transportation. A review of formation control structures is given, together with a discussion of special issues that arise in coordination of independent vehicles.</p><p>The main contributions of this thesis may be grouped into two categories:</p><p>• Path-following designs for controlling a group of vehicles</p><p>• Multi-body motivated formation modeling and control</p><p>A previously developed path following design is used to control a group of vehicles by synchronizing the individual path parameters. The path following design is advantageous since the path parameter, i.e., that parameter which determines position along a path, is scalar; hence coordination is achieved with a little amount of real-time communication. The path following design is also extended to the output-feedback case for systems where only parts of the state vector are known. The path following scheme is exploited further in a passivity-based design for coordination where the structural properties render an extended selection of functions for synchronization available. Performance and robustness properties in different operational conditions can be enhanced with a careful selection of these functions. Two designs are presented; a cascaded interconnection where a consensus system provides synchronized path parameters as input to the individual path following systems renders time-varying formations possible and increases robustness to communication problems; a feedback interconnection which is more robust to vehicle failures. Both designs are extended to sampled-data designs where plant and controller dynamics are updated in continuous-time and path parameters are exchanged over a communication network where transmission occurs at discrete intervals. Bias estimation is included to provide integral action against slowlyvarying environmental forces and model uncertainties.</p><p>A scheme for formation modeling and control, inspired by analytical mechanics of multi-body systems and Lagrangian multipliers, is proposed. In this approach to formation control, various formation behaviors are determined by imposing constraint functions on group members. Several examples illustrate these formation behaviors. The stabilization scheme presented is made more robust with respect to unknown time-varying disturbances. In addition, the scheme is extended towards adaptive estimation of unknown plant and parameters. Furthermore, it can be applied with no major modifications to the case of position control for a single vehicle.</p><p>The formation control scheme is such that it may be used in combination with a set of position control laws for a single vessel, thus enabling the designer to choose from a large class of control laws available in the literature. The input-to-state stability (ISS) framework is utilised to investigate robustness to environmental and communication disturbances. A loop-transform, together with the ISS framework, yields an upper bound on the inter-vessel time delay below which formation stability is maintained.</p>
19

Coordinated Control of Marine Craft

Ihle, Ivar-Andre Flakstad January 2006 (has links)
This thesis contains new results on the problem of coordinating a group of vehicles. The main motivation driving this work is the development of control laws that steer individual members of a formation, such that desired group behavior emerges. Special attention is paid to analysis of coordination issues, in particular formation control of marine craft where robustness to unknown environmental forces is important. Coordinated control applications for marine craft include: underway replenishment, maintaining a formation for increased safety during travel and instrument resolution, and cooperative transportation. A review of formation control structures is given, together with a discussion of special issues that arise in coordination of independent vehicles. The main contributions of this thesis may be grouped into two categories: • Path-following designs for controlling a group of vehicles • Multi-body motivated formation modeling and control A previously developed path following design is used to control a group of vehicles by synchronizing the individual path parameters. The path following design is advantageous since the path parameter, i.e., that parameter which determines position along a path, is scalar; hence coordination is achieved with a little amount of real-time communication. The path following design is also extended to the output-feedback case for systems where only parts of the state vector are known. The path following scheme is exploited further in a passivity-based design for coordination where the structural properties render an extended selection of functions for synchronization available. Performance and robustness properties in different operational conditions can be enhanced with a careful selection of these functions. Two designs are presented; a cascaded interconnection where a consensus system provides synchronized path parameters as input to the individual path following systems renders time-varying formations possible and increases robustness to communication problems; a feedback interconnection which is more robust to vehicle failures. Both designs are extended to sampled-data designs where plant and controller dynamics are updated in continuous-time and path parameters are exchanged over a communication network where transmission occurs at discrete intervals. Bias estimation is included to provide integral action against slowlyvarying environmental forces and model uncertainties. A scheme for formation modeling and control, inspired by analytical mechanics of multi-body systems and Lagrangian multipliers, is proposed. In this approach to formation control, various formation behaviors are determined by imposing constraint functions on group members. Several examples illustrate these formation behaviors. The stabilization scheme presented is made more robust with respect to unknown time-varying disturbances. In addition, the scheme is extended towards adaptive estimation of unknown plant and parameters. Furthermore, it can be applied with no major modifications to the case of position control for a single vehicle. The formation control scheme is such that it may be used in combination with a set of position control laws for a single vessel, thus enabling the designer to choose from a large class of control laws available in the literature. The input-to-state stability (ISS) framework is utilised to investigate robustness to environmental and communication disturbances. A loop-transform, together with the ISS framework, yields an upper bound on the inter-vessel time delay below which formation stability is maintained.
20

Instruction-set-simulator-less Virtual Prototype Framework for Embedded Software Development

Ni, Nick 15 December 2011 (has links)
With continuous advancement in silicon technology and high feature demands on consumer electronics, the complexity of embedded software has led the software development effort to dominate System-On-Chip (SoC) design. Virtual Prototype (VP) addresses the problem by enabling early software development before hardware arrival. However, VP still poses challenges: 1) Instruction Set Simulator (ISS) degrades simulation time, 2) Development is restricted to embedded processor specific tools and 3) Applications and drivers are dependent on system software completion. In this work, we propose an abstraction framework which: 1) Removes ISS from VP, achieving native host software execution time, 2) Activates rich suites of desktop development tools in host by compiling embedded software in host binary and 3) Allows system software independent application and driver development. With this framework, we successfully demonstrated up to 2000% speed-up in VP run-time over conventional VP and improved software development productivity significantly.

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