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1
Wang, Bo. "Analysis and implementation of time-delay systems and networked control systems". Thesis, University of South Wales, 2008. https://pure.southwales.ac.uk/en/studentthesis/analysis-and-implementation-of-timedelay-systems-and-networked-control-systems(f54e4378-db9b-443d-b505-88b4af5bb72a).html.
Testo completoAbstract (sommario):
Systems with delays frequently appear in engineering. The presence of delays makes system analysis and control design much more complicated. Networked control systems where the delays are often random are typical cases of such systems. For one particular category of time-delays systems, integral processes with dead time (IPDTs), the control limits that a PI controller can achieve are discussed in this thesis. These limits include the region of the control parameters to guarantee the system stability, the control parameters to achieve the given gain and/or phase margins (GPMs), the constraint on achievable gain and phase margins, the performance of set point tracking and disturbance rejection. Three types of PI controllers, namely typical PI controller, single tuning-parameter PI controller and PI controller under two-degree-of-freedom (2-DOF) structure, are studied. In control schemes of the modified Smith predictor (MSP) where the controller usually includes a distributed delay, the system implementation is not trivial because of the inherent hidden unstable poles. This thesis provides an estimation of the minimal number of implementation steps for the distributed delay in linear control laws. This is obtained by solving an inequality with respect to the number of implementation steps. A coarse estimation is given as the initial value to solve the inequality using bisection algorithms. A minimization process as well as some other techniques are also introduced to further improve the estimation. In networked control systems, the network-transmission delay and data dropout are combinedly represented by a network-induced delay. By designing a data pre processing mechanism, the network-induced delay can be assigned. Such delay as signment is applied to networked predictive control schemes, which alleviates systemstability limits on the network-induced delay. Two stability criteria are given for the closed-loop system with random network-induced delay, and a resulting implementation algorithm is also provided. The control and implementation of a magnetic levitation system over the network is studied in this thesis. Firstly, a test-rig which is suitable to implement control over a network is set up. Feedback linearization and direct local linearization methods for the nonlinear MagLev system are presented. In order to improve the control performance, a networked predictive method is employed, where the system model is identified in real-time. Local control and networked control are implemented on this test-rig, including networked predictive control. Model predictive control demonstrates a clear performance advantage over the networked control strategies which does not incorporate compensation for the network-induced delay. In order to quickly implement networked control systems (NCSs) by simulation or practical application, a MATLAB/Simulink based NCS toolbox is developed. This toolbox incorporates basic parts of a general NCS, that is, network simulation, network interface, plant interface and typical control schemes. With the NCS toolbox, users can focus on the study of new control schemes.
2
Koo, Kevin C. K. (Kevin Cheng Keong). "Investigating Army systems and Systems of Systems for value robustness". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59253.
Testo completoAbstract (sommario):
Thesis (S.M. in System Design and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 243-250).
This thesis proposes a value robustness approach to architect defense systems and Systems of Systems (SoS). A value robust system or SoS has the ability to provide continued value to stakeholders by performing well to meet the mission intent under a variety of future contexts. The proposed approach encompasses three methods, namely "Needs to Architecture" framework, Multi-Attribute Tradespace Exploration (MATE) and Epoch-Era Analysis. The architecting approach will commence with the "Needs to Architecture" framework. Stakeholders' needs are elicited and design concepts will be formulated. MATE is then used to screen, evaluate and select suitable design concepts. Subsequently, Epoch-Era Analysis is used to guide system architects to anticipate changes across foreseeable epochs, which are time periods of fixed needs and context. The tradespace analysis is repeated across all these epochs. Pareto Trace and Filtered Outdegree metrics will be used to identify passive and active value robust designs. The proposed value robustness approach is demonstrated conceptually using an Intelligence, Surveillance and Reconnaissance (ISR) system and an Army SoS case study. The proposed value robustness approach offers a potential methodology to design and evaluate complex defense systems such that they continue to be valuable to stakeholders over time. The method is also complementary to existing architecting methods such as modeling and simulation. The end product of applying this approach is a cost efficient defense system, which might be passively or actively value robust. High switching and modification costs might be avoided even if changes to the active value robust defense system are required. Through the use of the Army SoS case study discussion, the author suggests that a value robust defense SoS architecture is one that encompasses the desired ilities of changeability and interoperability.
by Kevin C.K. Koo.
S.M.in System Design and Management
3
Shah, Nirav Bharat 1979. "Influence strategies for systems of systems". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79341.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from department-submitted PDF version of thesis.
Includes bibliographical references (p. 141-149).
Distributed decision making has been identified as a source of managerial complexity for leaders of systems of systems (SoS). A new framework, AIR (Anticipation-Influence-Reaction), is proposed to capture the feedback relationships between the decisions made by constituents and those made by the managers of the SoS. AIR is then used to develop a five-member set of basic influences that can bring about changes in constituent behavior thus modifying the SoS. These influences, the 5 Is, are Incentives, Information, Infrastructure, Integration, and Institutions. AIR and the influences are demonstrated through qualitative application to real-world SoSs and quantitatively through simulation of an inter-modal freight transport network. It is found that cooperation between competing constituents, i.e., rail and truck carriers, can be quite fragile and sensitive to the SoS context. Careful, dynamic planning of influence strategies is needed to maintain SoS behavior in the face of constituents who are driven by self-interest and a limited, local perspective of the SoS.
by Nirav Bharat Shah.
Ph.D.
4
Wolf, Robert A. "Multiobjective collaborative optimization of systems of systems". Thesis, Cambridge, Massachusetts, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/10945/37786.
Testo completoAbstract (sommario):
CIVINSConcept studies for warship designs typically focus on ship performance characteristics by setting design goals for such things as speed, range, and cost. However, warships generally operate as part of a larger battle or strike group. Therefore, the designs should be evaluated as part of a system of multiple ship systems since designing each ship individually may result in underutilized and excess equipment and capability; in other words an inefficient design of the system of systems. This thesis examines the simultaneous design of several ships using the sea base concept as an example application of a network of ships working together. The number and characteristics of these ships determine the mission performance of the sea base. To properly design any of the sea base ships, the interrelationships must be included. A mission simulation is used to combine the performance characteristics of different ship designs into a singleperformance objective: the time to deliver a brigade size force to its assigned objectives. To enable the design of multiple ships, collaborative optimization, a multilevel optimization approach, was used to decompose the problem into individual ship design optimizations with system level interfaces controlled by a system of systems optimization algorithm. This allowed each ship to use techniques and algorithms best suited to reach an optimal design without impacting the design approaches used used by the other ships. The classical collaborative optimization approach was relaxed to include multiple objectives such as performance and cost, thus developing a range of solutions which represent the tradeoff between these objectives.
5
Wolf, Robert A. (Robert Allen). "Multiobjective collaborative optimization of systems of systems". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33596.
Testo completoAbstract (sommario):
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, 2005.Includes bibliographical references (p. 85-88).
Concept studies for warship designs typically focus on ship performance characteristics by setting design goals for such things as speed, range, and cost. However, warships generally operate as part of a larger battle or strike group. Therefore, the designs should be evaluated as part of a system of multiple ship systems since designing each ship individually may result in underutilized and excess equipment and capability; in other words an inefficient design of the system of systems. This thesis examines the simultaneous design of several ships using the sea base concept as an example application of a network of ships working together. The number and characteristics of these ships determine the mission performance of the sea base. To properly design any of the sea base ships, the interrelationships must be included. A mission simulation is used to combine the performance characteristics of different ship designs into a single performance objective: the time to deliver a brigade size combat force to its assigned objectives.
(cont.) To enable the design of multiple ships, collaborative optimization, a multilevel optimization approach, was used to decompose the problem into individual ship design optimizations with system level interfaces controlled by a system of systems optimization algorithm. This allowed each ship to use techniques and algorithms best suited to reach an optimal design without impacting the design approaches used by the other ships. The classical collaborative optimization approach was relaxed to include multiple objectives such as performance and cost, thus developing a range of solutions which represent the tradeoff between these objectives.
by Robert A. Wolf.
S.M.
Nav.E.
6
Bashar, Abusaksaka Aolo Bashar Ali. "Properties of delay systems and diffusive systems". Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/10553/.
Testo completoAbstract (sommario):
In this thesis, we investigate questions about the properties of delay systems and diffusive systems as well as Hankel and weighted Hankel operators. After detailing the necessary background in Chapter 1, in Chapter 2 the focus is on the development of methods to study the stability of delay and fractional systems. This analysis is carried forward using some BIBO and H∞ stability tests. Generalisation of the Walton-Marshall method [38] enable us to move from the single and multi-delay cases to fractional delay systems. This method gives procedures for finding stability windows as the delay varies. Chapter 3 is concerned with diffusive systems. Via convenient adaptations of some tests due to Howland [19], it becomes possible to give necessary and sufficient conditions for the Hankel operator and the weighted Hankel operator to be nuclear. Also, in this Chapter we introduce more general weighted Hankel operators and discuss their boundedness. Here the reproducing kernel test plays an essential role in testing boundedness. Some fundamental examples are given to support our work. In Chapter 4 here we investigate questions regarding approximating infinitedimensional linear system by finite-dimensional ones. Moreover, we develop more research on the rate of decay of singular values of the associated Hankel operator. In Chapter 5 we mainly focus on diffusive systems defined by holomorphic distributions and measures on a half plane. In particular we look at the nuclearity (trace class) and Hilbert-Schmidt properties of such systems. Moreover, we begin further study of explicit examples of weighted Hankel operators for which we did not know whether they were bounded, those examples already introduced in Chapter 3. In Chapter 6 the boundedness of weighted Hankel corresponding to diffusive systems is analysed using the theory of Carleson measures. Chapter 7 gives some suggestions for further work.
7
Johnson, Philip. "Evaluating systems of systems against mission requirements". Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/9116.
Testo completoAbstract (sommario):
This thesis investigates the nature of systems problems and the need for an open viewpoint to explain a system by viewing it as part of a larger whole and explaining its role in terms of that larger whole. The problem this research investigates is wicked and hence is unique in each instance. Therefore, an empirical proof would only hold for that particular instantiation of the problem, not the problem as a whole. After exposing some of the limitations of traditional systems engineering to this type of problem it is clear that a new approach is needed. The approach taken in the thesis is model driven and it is the architecture of this approach that is the stable artefact rather than the artefacts of a particular solution. The approach developed in this research has been demonstrated to be practicable. Specifically, this research has developed and demonstrated a novel approach for a decision support system that can be used to analyse a system of systems as part of a larger whole from both open and closed viewpoints in order to support the decision of which systems to use to conduct a particular military mission. Such planning decisions are wicked due to the uncertain and unique nature of military missions. Critical rationalism was used to validate the model driven approach and to falsify a parametric approach representative of traditional systems engineering through historical case studies. The main issue found with the parametric approach was the entanglement of functionality with the individual systems selected to implement the system of systems. The advantage of the model driven approach is that it separates functionality from implementation and uses model transformation for systems specification. Thus, although wicked problems do not have an exhaustively describable set of potential solutions this thesis has shown that they are not unapproachable.
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Abdalla, Gabriel. "Establishment of an ontology for Systems-of-Systems". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-10112017-160820/.
Testo completoAbstract (sommario):
Systems-of-Systems (SoS) represent an emerging research field in the Software Engineering area. In particular, SoS refer to systems that make possible the interoperability of distributed, complex systems, cooperating among them to reach a common mission. Several SoS have already been developed and used, but there is no consensus about diverse terms and concepts in this field, what can make difficult the communication among different stakeholders involved in the development and evolution of SoS, besides lacking of a standardization and common understanding among researchers and practitioners. This Masters project established OntoSoS, an ontology to formalize terms and concepts in the SoS field, expliciting and allowing sharing and reuse of knowledge contained in such ontology. As a result, this project intends to contribute to the field of SoS, also supporting activities related to SoS Engineering. It is also expected that this ontology can serve as a learning material in courses related to SoS.Sistemas-de-Sistemas (do inglês, Systems-of-Systems ou simplesmente SoS) representam um campo emergente de pesquisa na Engenharia de Software. Em particular, SoS referem-se a sistemas que possibilitam a interoperabilidade de sistemas complexos, distribuídos, cooperando entre si para atingir uma missão comum. Diversos SoS têm sido desenvolvidos e utilizados, mas não há um consenso sobre os diversos termos e conceitos nesse campo, o que pode dificultar a comunicação entre os diferentes interessados envolvidos no desenvolvimento e evolução dos SoS, além da falta de padronização e entendimento comum entre pesquisadores e profissionais. Este projeto de Mestrado estabeleceu a OntoSoS, uma ontologia para formalizar termos e conceitos no campo de SoS, explicitando e permitindo o compartilhamento e reúso do conhecimento contido na ontologia. Como resultado, este projeto pretende contribuir para o campo de SoS, auxiliando também nas atividades relacionadas à Engenharia de SoS. É também esperado que essa ontologia possa servir como um material de ensino em cursos relacionados à Engenharia de SoS.
9
Hanic, Dzana, e Amer Surkovic. "An Attack Model of Autonomous Systems of Systems". Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-39810.
Testo completoAbstract (sommario):
Context: In order to provide more functionalities and services, systems collaborate with each other creating more complex systems called Systems of Systems. Exploiting security vulnerabilities in such complex systems has an impact over system safety and it is not sufficient to analyze them separately in the development process. Observing these safety and security interdependencies together can be done via the process of attack modeling where attack models deploy a model for detecting vulnerabilities and possible mitigation strategies while observing system security from an adversary point of view. Objective: The aim of the thesis is to explore the interdependencies between safety and security concerns, to provide details on attack model(s) and affected safety requirements of given system, to argument that the system is acceptably safe to operate, and to contribute to the identified business challenges. Method: The thesis work consists of: (i) a literature survey on interdependencies between safety and security, and a literature survey on the existing attack models; (ii) a demonstration on a use case where the argument that the given system is acceptably safe with respect to the selected attack model has been provided using Goal Structuring Notation (GSN). Conclusion: The first literature survey conducted on the topic of interdependencies between safety and security has resulted in a number of papers addressing the importance of investigating safety and security together. Reviewed papers have been focused either on proposing new approaches or extending the existing ones in different industry domains like automotive, railway, industrial, etc. The literature survey on existing attack models has resulted in a number of papers elaborating attack models in general and showing domain-specific attack models such as those in control systems, vehicles, Cloud Computing, IoT, networks, RFID, Recommender Systems, etc. To provide an argument that the given system is acceptably safe by using GSN, investigated results from the selected attack model showed how to protect system while observing it from an adversary point of view. Including security countermeasures, i.e. data and identity authentication and implementation of access control in the system development process can produce an acceptably safe system, whilst, at the same time, affect different business aspects by introducing latency and delay to the system. However, avoiding such mitigation techniques may have catastrophic impact on the system and its environment when attacks are launched.
10
Rodríguez, Lina María Garcés. "A reference architecture of healthcare supportive home systems from a systems-of-systems perspective". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-16102018-111654/.
Testo completoAbstract (sommario):
Population ageing has been taking place all over the world, being estimated that 2.1 billion people will be aged 60 or over in 2050. Healthcare Supportive Home (HSH) Systems have been proposed to overcome the high demand of remote home care for assisting an increasing number of elderly people living alone. Since a heterogeneous team of healthcare professionals need to collaborate to continually monitor health status of chronic patients, a cooperation of pre-existing e-Health systems, both outside and inside home, is required. However, current HSH solutions are proprietary, monolithic, high coupled, and expensive, and most of them do not consider their interoperation neither with distributed and external e-Health systems, nor with systems running inside the home (e.g., companion robots or activity monitors). These systems are sometimes designed based on local legislations, specific health system configurations (e.g., public, private or mixed), care plan protocols, and technological settings available; therefore, their reusability in other contexts is sometimes limited. As a consequence, these systems provide a limited view of patient health status, are difficult to evolve regarding the evolution of patients health profile, do not allow continuous patients monitoring, and present limitations to support the self-management of multiple chronic conditions. To contribute to solve the aforementioned challenges, this thesis establishes HomecARe, a reference architecture for supporting the development of quality HSH systems. HomecARe considers HSH systems as Systems-of-Systems (SoS) (i.e., large, complex systems composed of heterogeneous, distributed, and operational and managerial independent systems), which achieve their missions (e.g., improvement of patients quality of life) through the behavior that emerges as result of collaborations among their constituents. To establish HomecARe, a systematic process to engineer reference architectures was adopted. As a result, HomecARe presents domain knowledge and architectural solutions (i.e., architectural patterns and tactics) described using conceptual, mission, and quality architectural viewpoints. To assess HomecARe, a case study was performed by instantiating HomecARe to design the software architecture of DiaManT@Home, a HSH system to assist at home patients suffering of diabetes mellitus. Results evidenced HomecARe is a viable reference architecture to guide the development of reusable, interoperable, reliable, secure, and adaptive HSH systems, bringing important contributions for the areas of e-Health, software architecture, and reference architecture for SoS.O envelhecimento da população é um fenômeno mundial e estima-se que no ano 2050, 2,1 bilhões de pessoas terão 60 anos ou mais. Sistemas de casas inteligentes para o cuidado da saúde (em inglês Healthcare Supportive Home - HSH systems) têm sido propostos para atender a alta demanda de serviços de monitoramento contínuo do número cada vez maior de pacientes que vivem sozinhos em suas residências. Considerando que o monitoramento do estado de saúde de pacientes crônicos requer a colaboração de equipes formadas por profissionais de várias especialidades, é fundamental que haja cooperação entre sistemas eletrônicos de saúde (por exemplo, sistemas de prontuário eletrônico ou sistemas de atenção de emergência), sendo eles externos ou internos à residência. Entretanto, as soluções de HSH existentes são comerciais, monolíticas, altamente acopladas e de alto custo. A maioria delas não considera a interoperabilidade entre sistemas distribuídos e exteriores ou internos à residência dos pacientes, como é o caso de robôs de companhia e monitores de atividade. Além disso, os sistemas de HSH muitas vezes são projetados com base em legislações locais, na estrutura do sistema de saúde (por exemplo, público, privado ou misto), nos planos de cuidados nacionais e nos recursos tecnológicos disponíveis; portanto, a reusabilidade desses sistemas em outros contextos é não é uma tarefa trivial. Em consequência, os sistemas de HSH existentes oferecem uma visão restrita do estado de saúde do paciente, são difíceis de evoluir acompanhando as mudanças no perfil de saúde do paciente, impossibilitando assim seu monitoramento contínuo e limitando o suporte para o paciente na autogestão de suas múltiplas condições crônicas. Visando contribuir na resolução dos desafios apresentados, esta tese estabelece a HomecARe, uma arquitetura de referência para apoiar o desenvolvimento de sistemas de HSH de qualidade. A HomecARe considera os sistemas de HSH como Sistemas-de-Sistemas (do inglês Systems-of-Systems - SoS) (ou seja, sistemas grandes e complexos formados por outros sistemas heterogêneos, distribuídos e que apresentam independência em seu gerenciamento e operação), que cumprem suas missões (por exemplo, melhoria da qualidade de vida do paciente) mediante o comportamento que emerge resultante da colaborações entre seus sistemas constituintes. Para estabelecer a HomecARe, foi adotado um processo sistemático que apoia a engenharia de arquiteturas de referência. Como resultado, a HomecARe contém o conhecimento do domínio, bem como soluções arquiteturais (por exemplo, padrões arquiteturais e táticas) que são descritas usando os pontos de vista conceitual, de missão e de qualidade. A HomecARe foi avaliada por meio da condução de um estudo de caso em que a arquitetura de referência foi instanciada para projetar o DiaManT@Home, um sistema de HSH que visa apoiar pacientes diagnosticados com diabetes mellitus na autogestão de sua doença. Os resultados obtidos evidenciaram que a HomecARe é uma arquitetura de referência viável para guiar o desenvolvimento de sistemas de HSH reusáveis, interoperáveis, confiáveis, seguros e adaptativos, trazendo importantes contribuições nas áreas de saúde eletrônica, arquitetura de software e arquiteturas de referência para SoS.
11
Chattopadhyay, Debarati. "A method for tradespace exploration of systems of systems". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50607.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.Includes bibliographical references (p. 211-215).
Systems of Systems (SoS) are a current focus of many organizations interested in integrating assets and utilizing new technology to create multi-component systems that deliver value over time. The dynamic composition of SoS along with the managerial independence of their component systems necessitates systems engineering considerations and methods beyond those of traditional systems engineering, particularly for SoS concept design. Qualitative and heuristic-based guidance is available in the literature, but there is a need for a method that will allow decision makers to quantitatively compare diverse multi-concept SoS designs on an equal basis in order to select value robust designs during concept exploration. Development of a quantitative method for SoS conceptual design will enable the consideration of many more architecture options than is possible through qualitative methods alone, facilitating a more complete exploration of a SoS design space. In this thesis, a quantitative method for SoS conceptual design, known as System of Systems Tradespace Exploration Method (SoSTEM), is presented. This method is based on the existing Dynamic Multi-Attribute Tradespace Exploration (MATE) which is a formal methodology for tradespace exploration during system design that allows the decision maker to make trades between both stakeholder preferences and systems early in the design process and includes the consideration of dynamic issues such as unarticulated stakeholder preferences and changing system context.
(cont.) In SoSTEM, SoS-level performance attributes are generated through a combination of component system attributes and system latent value, allowing the generation of SoS tradespaces where multi-concept architectures can be compared on the same performance and cost basis. This method allows the SoS designer to distinguish between component systems having high likelihood of participation in the SoS and those with lower likelihood of participation, based on the level of 'Effective Managerial Authority' that the SoS designer has over the component. SoSTEM is demonstrated through application to two case studies, an Operationally Responsive System for Disaster Surveillance and Satellite Radar.
by Debarati Chattopadhyay.
S.M.
12
Migliorini, Gabriele 1970. "Renormalization-group studies of disordered magnetic systems, strongly correlated electonic systems, and polymeric systems". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85333.
Testo completo
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Moro, Puppi Wanderley Gregory. "A framework for facilitating the development of systems of systems". Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2425/document.
Testo completoAbstract (sommario):
Le développement de Systèmes de Systèmes a pris de l'ampleur dans de nombreux domaines. Aujourd'hui, les applications complexes nécessitent que plusieurs systèmes développés indépendamment coopèrent ensemble, ce qui conduit au concept de Systèmes de Systèmes. Malgré une telle popularité, aucun consensus n'y a pas encore pu être atteint sur une définition précise de ce que sont les Systèmes de Systèmes. De plus, le nœud du problème est que la plupart des applications sont encore construites à la main et développées de manière ad hoc, c'est-à-dire, sans contraintes et sans être guidées par une structure prédéfinie. Développer un système de systèmes à la main est une tâche herculéenne pour un architecte informatique, en lui demandant de créer un entrelacement de connexions entre les systèmes composant du Système de Systèmes pour qu'ils puissent coopérer. En raison d'un tel entrelas, la complexité et le couplage serré augmentent, et l'évolution des Systèmes de Systèmes devient plus difficile, nécessitant des efforts substantiels. Pour trancher le nœud gordien auquel font face les architectes de Systèmes de Systèmes, nous proposons dans cette recherche un « framework » générique pour faciliter le développement de Systèmes de Systèmes dans le cadre de l'ingénierie des systèmes. Notre approche introduit une nouvelle architecture que nous appelons MBA pour Memory-Broker-Agent. Pour tester notre framework, nous avons construit un système de systèmes dans le domaine du développement collaboratif de logiciel. Les résultats montrent que notre approche réduit la difficulté et l'effort de développement. Sur la base de ces résultats, nous avons créé une méthode originale pour construire un système de systèmes à travers notre framework. Nous avons testé le potentiel de notre méthode ainsi que les caractéristiques génériques de notre framework, en construisant avec succès et avec plus de précision un nouveau système de systèmes dans le domaine de la SantéBuilding Systems of Systems (SoS) has gained momentum in various domains. Today, complex applications require to let several systems developed independently cooperate, leading to the moniker of SoS. Despite such popularity, no consensus has yet been reached about a precise definition of what SoS are. Moreover, the crux of the matter is that most applications are still handcrafted, being developed in an ad hoc fashion, i.e., freely and without being constrained by a predefined structure. Handcrafting SoS is an Herculean task for architects, requiring them to create an interwoven set of connections among SoS constituent systems for allowing cooperation. Because of the large number of interconnections, the complexity and tight coupling increase in SoS, and their evolution becomes more difficult, requiring substantial efforts from architects. To sever the Gordian knot faced by SoS architects, we propose in this research a generic framework for facilitating the development of SoS from a systems engineering perspective. Our approach is based on a novel architecture we call MBA for Memory-Broker-Agent. To test our framework we built an SoS for developing software collaboratively. Results show that our approach reduces the difficulty and effort for developing a SoS. Based on such results, we created an original method for building a SoS using our framework. We tested the potential of our method along with the generic features of our framework, by building a new SoS in the Health Care domain successfully and more accurately
14
Despotou, Georgios. "Managing the evolution of dependability cases for systems of systems". Thesis, University of York, 2007. http://etheses.whiterose.ac.uk/11059/.
Testo completoAbstract (sommario):
Dependability is a composite property consisting of attributes such as reliability, availability, safety and security. The achievement of these attributes is often essential for the operational success of systems undertaking critical and complex tasks. Assurance that the final system will demonstrate the required dependability qualities, can be crucial to the acceptance of the system into service. Safety cases are a well established concept used to establish assurance about the safety properties of a system. However, safety cases focus only on one attribute of dependability. The principles and processes of creating an integrated dependability case - that assures all aspects of dependable system behaviour - are less well understood. A number of challenges are faced when attempting to support dependability case development. These include the systematic elicitation of dependability goals, the management and justification of trade-offs, and the evolution of multi-attribute arguments in step with the design process. This thesis addresses these challenges by defining a rigorous framework, accompanied by a set of methods, for establishing dependability cases. Firstly, a method for eliciting dependability requirements is defined by extending existing safety deviational analysis techniques. Secondly, a method for systematically identifying and managing justified trade-offs is presented. Thirdly, the thesis describes the co-evolution of dependability case arguments alongside system development - using a dependability case architecture that corresponds to system structures. Finally, the thesis unifies these contributions by defining a metamodel that captures and interrelates the concepts underlying the proposed methods. Evaluation of the work is presented by means of peer review, pilot studies and industrial examples.
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Alvsvåg, Øyvind. "HVAC-systems : Modeling, simulation and control of HVAC-systems". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13821.
Testo completoAbstract (sommario):
It is of interest for companies to keep the annual operating cost of their buildings as low as possible. A substantial share of the annual operating costs are due to the large amount of energy needed for heating of the ventilated air and heating of the rooms inside the buildings. Also much of the electrical energy in the world today is created using fossil fuel or charcoal. This has an environmental aspect and the consumers of energy becomes more and more aware of this. Thus reducing the energy used by a buildings HVAC system can save the users for considerable expenditures and also has an environmental aspect.To find an estimate of the energy consumption a mathematical model representing a building and its HVAC system have been made. This model has been made up of several smaller models representing each component present in the building. These models have then been implemented in verb|Simulink| and the response of the system has been simulated for different scenarios. From these simulations the energy consumption has been extracted and compared to each other. Thus the amount of energy saved for each scenario has been found. The models include two type of controllers to see whether or not the choice of controller design affects the energy efficiency of the system. These two controller designs are the PID controller and the MPC control scheme. Also a discretized and simplified model of the building to be used together with the MPC controller has been found using system identification. In addition to this a Kalman filter that estimates unknown states and filter out disturbances are included in the MPC control scheme.The results from the simulations using a PID controller indicates a possible annual saving of substantial amounts. Thus this report shows that the annual energy consumption in a building can be greatly reduced by introducing simple and relatively cheap modifications to the HVAC system. The results from the simulations using the MPC scheme indicates that even more energy can be saved using this advanced control scheme. However, in order to verify this the MPC controller needs to be fine tuned and several more experiments needs to be reviewed.
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Shen, Hao. "Embeddings of Simple Triple Systems and Resolvable Triple Systems". Doctoral thesis, Universite Libre de Bruxelles, 2001. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211561.
Testo completo
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Wedgwood, Kyle. "Dynamical systems techniques in the analysis of neural systems". Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13599/.
Testo completoAbstract (sommario):
As we strive to understand the mechanisms underlying neural computation, mathematical models are increasingly being used as a counterpart to biological experimentation. Alongside building such models, there is a need for mathematical techniques to be developed to examine the often complex behaviour that can arise from even the simplest models. There are now a plethora of mathematical models to describe activity at the single neuron level, ranging from one-dimensional, phenomenological ones, to complex biophysical models with large numbers of state variables. Network models present even more of a challenge, as rich patterns of behaviour can arise due to the coupling alone. We first analyse a planar integrate-and-fire model in a piecewise-linear regime. We advocate using piecewise-linear models as caricatures of nonlinear models, owing to the fact that explicit solutions can be found in the former. Through the use of explicit solutions that are available to us, we categorise the model in terms of its bifurcation structure, noting that the non-smooth dynamics involving the reset mechanism give rise to mathematically interesting behaviour. We highlight the pitfalls in using techniques for smooth dynamical systems in the study of non-smooth models, and show how these can be overcome using non-smooth analysis. Following this, we shift our focus onto the use of phase reduction techniques in the analysis of neural oscillators. We begin by presenting concrete examples showcasing where these techniques fail to capture dynamics of the full system for both deterministic and stochastic forcing. To overcome these failures, we derive new coordinate systems which include some notion of distance from the underlying limit cycle. With these coordinates, we are able to capture the effect of phase space structures away from the limit cycle, and we go on to show how they can be used to explain complex behaviour in typical oscillatory neuron models.
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Heng, Jiin Shyang. "On systems engineering processes in system-of-systems acquisition". Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5689.
Testo completoAbstract (sommario):
Approved for public release; distribution is unlimited.S results show that a low-risk SoS acquisition could continue with the current SE process as the benefits derived from an extensive front-end SE process are limited. Conversely, a high-risk SoS acquisition should adopt the SoS SE process proposed herein to enhance the SoS acquisition program's chance of success. It is highrisk SoS acquisitions such as the US Army's Future Combat System, the US Coast Guard's Deep Water System, the Joint Tactical Radio System (JTRS), and Homeland Security's SBInet that would likely benefit from the proposed SoS SE process.
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Kingston, Kenneth Samuel. "Applications of complex adaptive systems approaches to coastal systems". Thesis, University of Plymouth, 2003. http://hdl.handle.net/10026.1/474.
Testo completoAbstract (sommario):
This thesis investigates the application of complex adaptive systems approaches (e.g. Artificial Neural Networks and Evolutionary Computation) to the study of coastal hydrodynamic and morphodynamic behaviour. Traditionally, nearshore morphological coastal system studies have developed an understanding of those physical processes occurring on both short temporal, and small spatial scales with a large degree of success. The associated approaches and concepts used to study the coastal system at these scales have primarily been linear in nature. However, when these approaches to studying the coastal system are extended to investigating larger temporal and spatial scales, which are commensurate with the aims of coastal management, results have had less success. The lack of success in developing an understanding of large scale coastal behaviour is to a large extent attributable to the complex behaviour associated with the coastal system. This complexity arises as a result of both the stochastic and chaotic nature of the coastal system. This allows small scale system understanding to be acquired but prevents the larger scale behaviour to be predicted effectively. This thesis presents four hydro-morphodynamic case studies to demonstrate the utility of complex adaptive system approaches for studying coastal systems. The first two demonstrate the application of Artificial Neural Networks, whilst the latter two illustrate the application of Evolutionary Computation. Case Study #1 considers the nature of the discrepancy between the observed location of wave breaking patterns over submerged sandbars and the actual sandbar locations. Artificial Neural Networks were able to quantitatively correct the observed locations to produce reliable estimates of the actual sand bar locations. Case Study #2 considers the development of an approach for the discrimination of shoreline location in video images for the production of intertidal maps of the nearshore region. In this case the system modelled by the Artificial Neural Network is the nature of the discrimination model carried out by the eye in delineating a shoreline feature between regions of sand and water. The Artificial Neural Network approach was shown to robustly recognise a range of shoreline features at a variety of beaches and hydrodynamic settings. Case Study #3 was the only purely hydrodynamic study considered in the thesis. It investigated the use of Evolutionary Computation to provide means of developing a parametric description of directional wave spectra in both reflective and nonreflective conditions. It is shown to provide a unifying approach which produces results which surpassed those achieved by traditional analysis approaches even though this may not strictly have been considered as a fiddly complex system. Case Study #4 is the most ambitious application and addresses the need for data reduction as a precursor when trying to study large scale morphodynamic data sets. It utilises Evolutionary Computation approaches to extract the significant morphodynamic variability evidenced in both directly and remotely sampled nearshore morphologies. Significant data reduction is achieved whilst reWning up to 90% of the original variability in the data sets. These case studies clearly demonstrate the ability of complex adaptive systems to be successfully applied to coastal system studies. This success has been shown to equal and sometimess surpass the results that may be obtained by traditional approaches. The strong performance of Complex Adaptive System approaches is closely linked to the level of complexity or non-linearity of the system being studied. Based on a qualitative evaluation, Evolutionary Computation was shown to demonstrate an advantage over Artificial Neural Networks in terms of the level of new insights which may be obtained. However, utility also needs to consider general ease of applicability and ease of implementation of the study approach. In this sense, Artificial Neural Networks demonstrate more utility for the study of coastal systems. The qualitative assessment approach used to evaluate the case studies in this thesis, may be used as a guide for choosing the appropriateness of either Artificial Neural Networks or Evolutionary Computation for future coastal system studies.
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Sinclair, Jane. "Action systems, determinism and the development of secure systems". Thesis, Open University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389245.
Testo completo
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Ozbayrak, M. "Design of tool management systems for flexible manufacturing systems". Thesis, Loughborough University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359905.
Testo completo
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Maree, Charl. "Diagnostic monitoring of dynamic systems using artificial immune systems". Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1780.
Testo completoAbstract (sommario):
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2006.The natural immune system is an exceptional pattern recognition system based on memory and learning that is capable of detecting both known and unknown pathogens. Artificial immune systems (AIS) employ some of the functionalities of the natural immune system in detecting change in dynamic process systems. The emerging field of artificial immune systems has enormous potential in the application of fault detection systems in process engineering. This thesis aims to firstly familiarise the reader with the various current methods in the field of fault detection and identification. Secondly, the notion of artificial immune systems is to be introduced and explained. Finally, this thesis aims to investigate the performance of AIS on data gathered from simulated case studies both with and without noise. Three different methods of generating detectors are used to monitor various different processes for anomalous events. These are: (1) Random Generation of detectors, (2) Convex Hulls, (3) The Hypercube Vertex Approach. It is found that random generation provides a reasonable rate of detection, while convex hulls fail to achieve the required objectives. The hypercube vertex method achieved the highest detection rate and lowest false alarm rate in all case studies. The hypercube vertex method originates from this project and is the recommended method for use with all real valued systems, with a small number of variables at least. It is found that, in some cases AIS are capable of perfect classification, where 100% of anomalous events are identified and no false alarms are generated. Noise has, expectedly so, some effect on the detection capability on all case studies. The computational cost of the various methods is compared, which concluded that the hypercube vertex method had a higher cost than other methods researched. This increased computational cost is however not exceeding reasonable confines therefore the hypercube vertex method nonetheless remains the chosen method. The thesis concludes with considering AIS’s performance in the comparative criteria for diagnostic methods. It is found that AIS compare well to current methods and that some of their limitations are indeed solved and their abilities surpassed in certain cases. Recommendations are made to future study in the field of AIS. Further the use of the Hypercube Vertex method is highly recommended in real valued scenarios such as Process Engineering.
23
Stockton, Nicklas O. "Hybrid Genetic Fuzzy Systems for Control of Dynamic Systems". University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1523635312922039.
Testo completo
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Bouziat, Teddy. "A Cooperative Architecting Procedure for Systems of Systems Based on Self-Adaptive Multi-Agent Systems". Thesis, Toulouse 1, 2017. http://www.theses.fr/2017TOU10069.
Testo completoAbstract (sommario):
Depuis la seconde guerre mondiale, l’ingénierie des systèmes a permis le développement de méthodologies pour contrôler le développement de systèmes et de projets de plus en plus complexes. En 1990, la chute de l’URSS a provoqué un changement de doctrine militaire aux Etats-Unis en passant d’une confrontation bipolaire à une mondialisation des conflits comportant une grande variété de menaces. Sa nouvelle doctrine était de faire collaborer ses systèmes de défense existants pour produire un système de défense de haut niveau, décentralisé, adaptable et composé de systèmes indépendants. C’est l’apparition du concept de Système de Systèmes (SdS).Cette thèse de doctorat propose un nouveau modèle de SdS appelé SApHESIA (SoS ArchitectingHEuriStIc based on Agent), ainsi qu’une nouvelle méthodologie d’architecture. Cette nouvelle méthodologie est basée sur une coopération complète entre tous les composants du SdS, lui permettant d’évoluer de lui-même afin de faire face à des événements inattendus de son environnement tels que des menaces. Enfin, ce travail est testé à travers 4exemples issus de différents domaines (militaire, logistique et exploratoire)Since the World War II, researchers have tended to develop methodologies and tools tobuild and control the development of more and more complex systems and projects. Thisinter-disciplinary research area has been called Systems Engineering (SE) and continues tobe developed nowadays. In 1990, the fall of USSR led the US Department of Defense (DoD)to re-think its defense doctrine and to switch from a one opponent confrontation to a globalizationof conflicts with a huge variety of scenarios. Its idea was to re-use and join itsdefense systems by producing a huge, decentralized and adaptive defense system that iscomposed of existing and independents (complex) systems. This is the apparition of theSystem of Systems (SoS) concept. After 2000’s, this concept spreads in civil domains suchas crisis management or logistic systems. More precisely, a SoS is a complex system characterizedby the particular nature of its components: these latter, which are systems, tend tobe managerially and operationally independent as well as geographically distributed. Thisspecific characterization led to re-think research areas of classic SE such as definition, taxonomy,modeling, architecting and so on. SoS architecting focuses on the way independentcomponents of a SoS can be dynamically structured and can change autonomously theirinteractions in an efficient manner to fulfill the goal of the SoS and to cope with the highdynamics of the environment. This PhD thesis mainly focuses on two SoS research areas: 1)SoS modeling and 2) SoS architecting. To achieve the first point, we propose a new modelcalled SApHESIA (SoS Architecting HEuriStIc based on Agent). We have used set theoryand ABM (Agent-Based Model) paradigm to define this model that takes into account thecharacteristics of SoS. Secondly, we propose a new SoS architecting procedure based on theAdaptive Multi-Agent System (AMAS) approach that advocates full cooperation betweenall the components of the SoS through the concept of criticality. This criticality is a metricthat represents the distance between the current state of a component and its goals. In thisprocedure, the SoS architecture evolves over time to self-adapt to the dynamics of the environmentin which it is plunged, while taking into account the respective local goals of itscomponents. Finally we instantiate this model and this procedure through 4 examples fromdifferent domains (military, logistics and exploratory missions) and validate the feasibility,the efficiency, the effectiveness and the robustness of the SoS architecting procedure we havedeveloped and proposed
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Larsson, Erik. "SYSTEMS OF INTERPRETATION". Thesis, Konstfack, Institutionen för Konst (K), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:konstfack:diva-2990.
Testo completoAbstract (sommario):
Every image locates intelligence.1 I decided to become an artist due to this premise. Mostof my childhood was spent in front of a TV-screen. By channel surfing across the rangeof our satellite dish I created new narratives of my own, based on the different channelsexisting images. The disappearance of images became as important as their appearance.Art offered me a way of preserving and study these transient images of contemporaryculture.
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Chernyakova, Irina. "Systems of valuation". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81659.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 69-75).
The 1972 publication of The Limits to Growth marked a watershed moment in ongoing environmental debates among politicians, economists, scientists, and the public in the postwar period. Sponsored by the Club of Rome, an influential think-tank established in 1968, the report was published against the backdrop of the progressive activism of the 1960s, and prefigured the neo-conservative politics of the 1980s. It represented a decisive moment in that it appeared to reconcile critiques of consumerism and capitalism by linking the limits of global consumption to a finite totality of resources on the planet. As a pre-history to current systems of valuation, this thesis looks at some of the intellectual tendencies that under-girded mindsets such as those manifest in the report. More importantly, it follows the intricate logics and narratives buried within the enigmatic web of geometric symbols and snaking lines that suffuse the writings of systems thinkers, tracing a genealogy of this mode of thought that begins with semiotic language of ecologists Eugene and Howard T. Odum, and of Jay Wright Forrester and the Systems Dynamics Group at MIT, to its manifold ends. These actors will ground the implications of systems theory-in-practice, its implications, and its biases. In doing so, the thesis reconstructs how "environment" was first defined and captured by systems thinking. Navigating through a series of international conferences in which these principles were substantiated, the thesis looks at the ramifications of systems thinking in the present.
by Irina Chernyakova.
S.M.
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McKee, Andrew. "Multipliers of dynamical systems". Thesis, Queen's University Belfast, 2017. https://pure.qub.ac.uk/portal/en/theses/multipliers-of-dynamical-systems(65b93a06-6e7b-420b-ae75-c28d373f8bdf).html.
Testo completoAbstract (sommario):
Herz–Schur multipliers of a locally compact group have a well developed theory coming from a large literature; they have proved very useful in the study of the reduced C∗-algebra of a locally compact group. There is also a rich connection to Schur multipliers,which have been studied since the early twentieth century, and have a large number of applications. We develop a theory of Herz–Schur multipliers of a C∗-dynamical system, extending the classical Herz–Schur multipliers, making Herz–Schur multiplier techniques available to study a much larger class of C∗-algebras. Furthermore, we will also introduce and study generalised Schur multipliers, and derive links between these two notions which extend the classical results describing Herz–Schur multipliers in terms of Schur multipliers. This theory will be developed in as much generality as possible, with reference to the classical motivation. After introducing all the necessary concepts we begin the investigation by defining generalised Schur multipliers. The main result is a dilation type characterisation of these multipliers; we also show how such multipliers can be represented using HilbertC∗-modules. Next we introduce and study generalised Herz–Schur multipliers, first extending a classical result involving the representation theory of SU(2), before studying how such functions are related to our generalised Schur multipliers. We give a characterisation of generalised Herz–Schur multipliers as a certain class of the generalised Schur multipliers, and obtain a description of precisely which Schur multipliers belong to this class. Finally, we consider some ways in which the generalised multipliers can arise; firstly, from the classical multipliers which provide our motivation, secondly, from the Haagerup tensor product of a C∗-algebra with itself, and finally from positivity considerations. We show that our theory behaves well with respect to positivity and give conditions under which our multipliers are automatically positive in a natural sense.
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Ed-Daoui, Ilyas. "Towards systems-of-systems structural resilience assessment Resilience assessment as a foundation for systems-of-systems safety evaluation : application to an economic infrastructure An approach to systems-of-systems structural analysis through interoperability assessment : application on Moroccan Case A study of an adaptive approach for systems-of-systems integration A contribution to systems-of-systems concept standardization Unstructured peer-to-peer systems : towards swift Routing A deterministic approach for systems-of-systems resilience quantification Vers des systèmes de systèmes robustes Security enhancement architectural model for IMS based networks Towards reliable IMS-based networks". Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR07.
Testo completoAbstract (sommario):
De nos jours, nous attendons des systèmes de systèmes d'être plus que simplement fonctionnel, mais aussi fiable, de préserver leurs performances, de mener les actions requises et, surtout, d'anticiper d'éventuelles défaillances. La résilience fait partie des nombreuses approches d'évaluation de la fiabilité. Elle est directement liée aux conséquences de perturbations et incertitudes. Il s'agit des conséquences en cas de perturbations et des incertitudes associées. La résilience est définie comme la capacité des systèmes à résister à une perturbation majeure selon paramètres de dégradation et à récupérer dans un délai, des coûts et des risques acceptables. Dans cette thèse, deux approches complémentaires sont proposées pour tenter d'analyser la résilience structurelle des systèmes de systèmes. La première est liée à l'extensibilité qui est une caractéristique des systèmes de systèmes puisqu'ils sont en continuelle évolution. L'un des principaux objectifs est d'évaluer la résilience structurelle en tenant compte de l'aspect dynamique et moyennant une évaluation de l'interopérabilité. D'autre part, un examen de la structure d'un système de systèmes et des flux internes représente la deuxième approche. Cela conduit à une évaluation de la résilience structurelle grâce à un ensemble d'indicateurs. Les deux approches proposées sont déterministes et peuvent être utilisées pour évaluer l'état courant de la structure du système de systèmes ou pour anticiper sa résilience dans des scénarios futurs. Un démonstrateur a été développé pour l'évaluation de la résilience structurelle. Dans la considération de territoires, il a servi à l'évaluation d'infrastructures industrielles réelles selon une approche systèmes de systèmesNowadays, we expect of SoS (systems-of-systems) more than just to be functional, but also to be reliable, to preserve their performance, to complete the required fonctions and rnost importantly to anticipate potential defects. The relationship with resilience is among the numerous perspectives tackling reliability in the context of SoS. It is about the consequences in case of disturbances and associated uncertainties. Resilience is defined as the ability of systems to withstand a major disruption within acceptable degradation parameters and to recover within an acceptable time, composite costs and risks. In this thesis, two complementary approaches are proposed in an attempt to analyze SoS structural resilience. First is related to extensibility which is a specific characteristic of SoS as they are in continuous evolvement and change. A major focus is to evaluate SoS structural resilience with regards to its dynamic aspect and through interoperability assessment. On the other hand, a consideration of the SoS structure and inner workflow pathways represents the second approach. This perspective leads to structural resilience assessment through a set of indicators. Both proposed approaches are deterministic and can be used to evaluate the current state of SoS structure or to anticipate its resilience in future scenarios. Futhermore, a prototype is designed in order to process the structural resilience assessment. Considering spatial objects, it has been used to conduct experiments on real-based industrial infrastructures approached as SoS
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Germanos, Vasileios. "Model checking of mobile systems and diagnosability of weakly fair systems". Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/3059.
Testo completoAbstract (sommario):
This thesis consists of two independent contributions. The rst deals with model checking of reference passing systems, and the second considers diagnosability under the weak fairness assumption. Reference passing systems, like mobile and recon gurable systems are everywhere nowadays. The common feature of such systems is the possibility to form dynamic logical connections between the individual modules. However, such systems are very di cult to verify, as their logical structure is dynamic. Traditionally, decidable fragments of -calculus, e.g. the well-known Finite Control Processes (FCP), are used for formal modelling of reference passing systems. Unfortunately, FCPs allow only `global' concurrency between processes, and thus cannot naturally express scenarios involving `local' concurrency inside a process. This thesis proposes Extended Finite Control Processes (EFCP), which are more convenient for practical modelling. Moreover, an almost linear translation of EFCPs to FCPs is developed, which enables e cient model checking of EFCPs. In partially observed systems, diagnosis is the task of detecting whether or not the given sequence of observed labels indicates that some unobservable fault has occurred. Diagnosability is an associated property, stating that in any possible execution an occurrence of a fault can eventually be diagnosed. In this thesis, diagnosability is considered under the weak fairness (WF) assumption, which intuitively states that no transition from a given set can stay enabled forever - it must eventually either re or be disabled. A major aw in a previous approach to WF-diagnosability in the literature is identi ed and corrected, and an e cient method for verifying WF-diagnosability based on a reduction to LTL-X model checking is presented.
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Becker, Basil. "Architectural modelling and verification of open service-oriented systems of systems". Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/7015/.
Testo completoAbstract (sommario):
Systems of Systems (SoS) have received a lot of attention recently. In
this thesis we will focus on SoS that are built atop the techniques of
Service-Oriented Architectures and thus combine the benefits and
challenges of both paradigms. For this thesis we will understand SoS
as ensembles of single autonomous systems that are integrated to a
larger system, the SoS. The interesting fact about these systems is
that the previously isolated systems are still maintained, improved
and developed on their own. Structural dynamics is an issue in SoS, as
at every point in time systems can join and leave the ensemble. This
and the fact that the cooperation among the constituent systems is not
necessarily observable means that we will consider these systems as open systems.
Of course, the system has a clear boundary at each point in time, but
this can only be identified by halting the complete SoS. However,
halting a system of that size is practically impossible. Often SoS
are combinations of software systems and physical systems. Hence a
failure in the software system can have a serious physical impact what
makes an SoS of this kind easily a safety-critical system.
The contribution of this thesis is a modelling approach that extends
OMG's SoaML and basically relies on collaborations and roles as an
abstraction layer above the components. This will allow us to describe
SoS at an architectural level. We will also give a formal semantics
for our modelling approach which employs hybrid graph-transformation
systems. The modelling approach is accompanied by a modular
verification scheme that will be able to cope with the complexity
constraints implied by the SoS' structural dynamics and size. Building such autonomous systems as SoS without evolution at the architectural level --- i. e. adding and removing of components and services --- is inadequate. Therefore our approach directly supports the modelling and verification of evolution.Systems of Systems (SoS) sind ein seit längerem bekanntes Konzept, das jedoch in letzter Zeit vermehrt Aufmerksamkeit erhielt. Das Hauptaugenmerk dieser Arbeit wird auf SoS liegen, die mit Hilfe von Techniken aus Service-Orientierten Architekturen erstellt werden. Somit vereinen die hier betrachteten SoS die Vorteile und Herausforderungen beider Paradigmen. SoS können definiert werden als Zusammenschlüsse einzelner, autonomer Systeme, die zu einem größeren System integriert werden. In diesem Zusammenhang interessant ist, dass die ehemals isolierten Systeme nach wie vor isoliert voneinander weiterentwickelt und gewartet werden. Desweiteren kommt der Strukturdynamik innerhalb des SoS eine beachtliche Bedeutung zu, da jederzeit Systeme dem SoS beitreten und es verlassen können. Zusammen mit der Tatsache, dass die Kooperationen zwischen den konstituierenden Systemen nicht immer beobachtbar sind, führt dies dazu, dass wir diese Systeme als offene Systeme bezeichnen. Wobei das System natürlich jederzeit eine klar definierte Grenze besitzt, diese aber nur durch ein Anhalten des Systems zu bestimmen ist. Dies jedoch ist, von einer praktischen Perspektive aus betrachtet, unmöglich. Häufig stellen SoS eine Kombination aus Softwaresystemen und pyhsikalischen Systemen dar mit der Folge, dass ein Fehler in der Software eine SoS schnell eine immense physikalische Wirkung entwickeln kann. Von daher fallen SoS leicht in die Klasse der sicherheitskritischen Systeme. In dieser Arbeit werden wir einen Modellierungsansatz vorstellen, der die Sprache SoaML der OMG erweitert. Die grundlegenden Konzepte dieses Ansatzes sind die Modellierung mit Kollaborationen und Rollen als Abstraktionsebene über Komponenten. Der vorgestellte Ansatz erlaubt es uns SoS auf einer architekturellen Ebene zu betrachten. Die formale Semantik unseres Modellierungsansatzes ist durch hybride Graphtransformationssysteme gegeben. Abgestimmt auf die Modellierung werden wir ebenfalls ein Verfahren zu Verifikation von SoS vorstellen, welches trotz der inhärenten Komplexität von SoS, diese zu verifizieren. Die Modellierung und Verifikation von Evolution wird von unserem Ansatz direkt unterstützt.
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Owarish, Miles I. "Concepts of integration of fire safety systems with building services systems". Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/523.
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GOMES, GEORGIA REGINA RODRIGUES. "INTEGRATION OF REPOSITORIES OF DIGITAL LIBRARY SYSTEMS AND LEARNING MANAGEMENT SYSTEMS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9944@1.
Testo completoAbstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCom o uso generalizado das tecnologias de informação no apoio ao ensino, é comum disponibilizar conteúdos digitais, seja através de Sistemas de Bibliotecas Digitais (DLMS) ou de Sistemas de Gerência de Aprendizagem (LMS). No entanto, estes sistemas funcionam de forma independente, têm características diferentes e manipulam tipos diferentes de materiais, sendo seus repositórios com dados e metadados heterogêneos e distribuídos. Os conteúdos destes repositórios seriam melhor aproveitados se estivessem integrados a um ambiente comum, ou fossem acessados de modo integrado a partir dos ambientes de de DLMS e LMS. Nesta tese é apresentada uma visão homogênea dos conteúdos de DLMS e LMS. Para esta homogeneização utilizou-se uma extensão da arquitetura de mediadores e tradutores que trata a integração de metadados, assim como ontologias para tratamento semântico. Foram consideradas ontologias locais para descrever os metadados de cada repositório e uma ontologia global para a integração. No entanto, os documentos dos repositórios dos DLMS tendem a ser monolíticos e não têm um enfoque na reutilização( reuso). Assim, foram definidas regras para extração dos conteúdos mais importantes destes documentos, o que possibilita a reutilização. Esta extração envolve técnicas de mineração de texto e utiliza regras para descobrir as definições contidas nos documentos. Foi desenvolvido um protótipo que demonstra a viabilidade do processo. Para facilitar o entendimento do trabalho, é apresentado um estudo de caso que utiliza a técnica proposta e o protótipo desenvolvido. O trabalho facilita e enriquece o desenvolvimento de materiais de aprendizagem, uma vez que torna os conteúdos de documentos das bibliotecas digitais reutilizáveis e integrados aos Objetos de Aprendizagem (LO) existentes.
With the widespread use of Information Technology for teaching support, it is usual to made digital content available through Digital Library Systems (DLMS) or Learning Management Systems (LMS).These systems, however, work independently, have different characteristics and manipulate different types of materials, and their data and metadata repositories are heterogeneous and distributed. The content of repositories would be better used if it was integrated in the same environment or accessed in an integrated way from DLMS and LMS. This thesis presents a homogeneous view of DLMS and LMS content. In order to provide such homogenization, it is proposed an extension of the mediator and wrapper architecture for dealing with metadata integration and ontologies for treating semantics. Local ontologies are used for describing each metadata repository, and a global ontology for the integration. As documents of DLMS repositories tend to be monolithic and not to follow a reuse approach, rules for extracting the most important content from these documents were developed in order to make them reusable. This extraction includes text mining techniques as well as rules for discovering definitions embedded in the documents. A prototype was developed which implements the extraction and proves the feasibility of this approach. In order to make the work easier to understand, it is presented a case study that uses the proposed technique and the prototype. The work described in this thesis facilitates and enriches the development of learning material by making the content of digital library documents reusable and integrated to existing learning objects.
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Mitchell, Tami Lee. "A New Method for the Examination of Policy Systems of Systems". Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/29506.
Testo completoAbstract (sommario):
This dissertation examines multi-agency policy environments as a policy system of systems (SoS). The research conducted for this dissertation establishes the need to develop a method of analysis suitable for the analysis of a policy SoS that allows for the examination of individual policy relationships while maintaining a holistic perspective of the entire SoS. The Three-Dimensional Policy Design Structure (3DPDS) is proposed as a method of analysis suitable for examination of a policy SoS. This dissertation focuses on application of the 3DPDS to three specific areas of space launch policy that impact space launch capacity: (1) policies related to space launch vehicles, (2) policies related to space launch facilities, and (3) the potential impacts of the cancellation of the Ares 1 launch vehicle. The first two applications of the 3DPDS provide a retrospective analysis of the policy relationships within the space launch policy SoS. The final application uses the results of the examination of policies related to space launch vehicles to systematically examine a current issue. The results of the first two applications, when compared against data gathered from subject matter experts during the interview process, provided a much more complete and holistic perspective of the policy relationships within the SoS, including identification of policy outliers. The third application enabled a systematic review of a current policy issue that incorporated information from formal policy documents with information provided by subject matter experts during the interview process.Ph. D.
34
Karlsson, Ingvar. "Applying Systems Approach to the Process of Designing Information Systems". Thesis, University of Skövde, Department of Computer Science, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-593.
Testo completoAbstract (sommario):
Designing information systems is a complex task. The purpose of this work is to contribute to an improved understanding of the design conditions in order to alleviate the problems that occur due to complexity in the design process. To possibly increase the understanding of the conditions for the design of interactive information systems, this dissertation concerns applying systems approach to the design situation. This is done in order to obtain understanding, but also to be able to identify the consequences and possible benefits of doing so. A literature survey and two extensive interviews have been performed. The material has been analysed, and tentative models of the design situation and its components are presented. These models can be considered general to the design situation and consequences are deduced from them. The result of this work is manifested in the tentative models, which describe the design situation, the designer, the user, the customer and the design. The concepts of complexity and communication have also been thoroughly dealt with.
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Wernstedt, Fredrik. "Multi-agent systems for distributed control of district heating systems /". Karlskrona : Blekinge Institute of Technology, 2005. http://www.bth.se/fou/Forskinfo.nsf/allfirst2/51e3dfb98bb6ba6bc1257107002f6d29?OpenDocument.
Testo completo
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Abdul, Samad Alaa. "Application of kinetic energy storage systems to power systems operation". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81523.
Testo completoAbstract (sommario):
This thesis analyzes some potential applications of kinetic energy (KE) storage systems in power systems operation. The goal was to take advantage of the KE stored in the existing rotating machines in a power system such as synchronous generators and motors by "borrowing" some of the stored KE when electricity prices are high and "returning" this energy to the rotating masses when the prices are down. As shown in this thesis, this operation can be performed from the control center by optimally scheduling the set points of the generators under automatic generation control (AGC) over a given time horizon. This coordination of KE was also tested with other types of rotating machines, namely synchronous and asynchronous flywheels.The specific impact of this optimum coordination of KE storage has been tested from the perspective of power systems economics and security by investigating the method's potential to reduce the marginal price of electricity and to alleviate network congestion. In addition, this thesis examines the potential of KE storage systems to produce fast (10-30 second) reserve to be used during primary frequency regulation following the forced outage of a generating unit.
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Bogdan, Paul. "Theoretical Foundations of Multicore Systems Design: A Dynamical Systems Perspective". Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/183.
Testo completoAbstract (sommario):
The proliferation of complex phenomena and the tightening competition for limited resources are two fundamental challenges for the modeling, analysis, and optimization of dynamical processes taking place in networked environments/architectures. Modes of collective and competitive behavior can be noticed across a wide array of social, biological, and technological contexts. From urban crowds to bacterial colonies, from brain neurons to human cells and even electron-hole interactions in semiconductors, dynamical phase transitions influence the macroscopic behavior of complex networks. To address these challenges, we focus on understanding, modeling, analyzing, and optimizing large-scale interconnected systems, such as future thousand-core Networks-on-Chip (NoC), biologically propelled Cyber-Physical Systems (CPS) consisting of micro-robotic swarms, or biological networks of stem cells, for performance, power, or fault-tolerance.
Enabled by recent advances in CMOS technology, the integration of tens and soon thousands of heterogeneous processing cores communicating via the NoC paradigm brings into the discussion the traffic modeling problem. Traffic modeling is of crucial importance for both static and dynamic NoC design and optimization problems such as topology selection and resource allocation, mapping, scheduling, routing or power management. The approaches proposed so far exhibit major limitations. For example, many of the queuing theory based modeling and optimization approaches proposed for NoC architectures ignore the traffic characteristics (e.g., non-stationarity, fractality). In many situations, these models lead to buffer overflow or deadline missing situations and so poor (non-optimal) performance levels.
In this thesis, we show how this state of affairs can be changed by embracing a statistical physics inspired approach in order to insure accurate network traffc characterization. By using an analogy between a thermodynamic gas and a networked multicore architecture, our model captures the relevant traffc characteristics (e.g., fractality, non-stationarity) via a dynamical master equation. Our approach not only leads to a more accurate estimation of performance metrics over Markovian models, but also helps at defining new state space model for dynamical systems that can be used for online optimization. Besides being an important contribution by itself, this radically new approach enhances the efficiency of resource allocation in nanoscale networks and overcomes the prior limitations of performance analysis approaches based on queuing models.
Building on statistical physics grounds, we model and analyze a biologically inspired communication protocol, namely the stochastic communication protocol. Under the stochastic communication protocol aiming at mitigating the nanoscale challenges (e.g., particle hits, cross-talk) in multi-core platforms, each node in the network disseminates packets multiple times via multiple paths. Hence, fault-tolerance is enforced at system-level by exploiting path diversity. To characterize such a dynamic behavior, we concentrate on estimating various performance metrics via a master equation approach capturing communication events such as packet duplication, packet transmission, and packet corruption. The proposed statistical physics model allows us to identify the benefits of this protocol for future communication fabrics.
To address the power consumption issues in large scale on-chip networks, we formulate the power and peak temperature management of heterogeneous NoC platforms as constrained finite horizon fractal optimal control problem. We show not only that fractal characteristics can be accounted for via fractional calculus state space models, but also that the online controller can be reduced to a linear program and efficiently computed via parallel algorithms. Our approach not only leads to significant power savings, but it also opens new avenues for dynamic optimization of large-scale systems exhibiting fractal dynamics.
Based on the proposed framework for modeling, analysis, and optimization of dynamical processes taking place on networked architectures, we formulate general guidelines for CPS design. As a concrete CPS example, we consider the design problem of the control algorithm of a pacemaker, which takes into account at run-time the fractal characteristics exhibited by heart rate variability.
In summary, this thesis offers a statistical physics view on using the network-paradigm in multicore and cyber-physical system design. The results and discussion presented herein can be further extended to other classes of systems and applications. One research direction is represented by modeling and optimization of bacteria propelled micro-robotic swarms. Another research direction concerns the modeling of human dynamic processes such as car traffic, which can enable road structure optimization. Moreover, by relying on this statistical physics inspired framework, we can define models for biological communication and heterogeneous population growth with applications in regenerative medicine.
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Wicht, Anthony C. (Anthony Charles). "Acquisition strategies for commonality across complex aerospace systems-of-systems". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68411.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 184-195).
Commonality is a system architecting strategy widely used to improve affordability and reliability of families of products. However not all commonality is beneficial, and organizations must balance commonality benefits and commonality costs to pursue a successful strategy. The existing literature on commonality assumes that all commonality decisions are made within a single organization. This is not the case for NASA's human exploration architectures which are acquired through a network of prime contractors and sub-contractors. This thesis examines how the acquisition strategies chosen for NASA's human exploration architectures affect the realization of commonality in those architectures, and suggests ways in which acquisition architectures can be planned to improve commonality outcomes. The thesis synthesizes the requirements of NASA's exploration architectures and commonality best practice from existing literature. It also examines the Federal Acquisition Regulations in detail to assess the limitations on government acquisition structures in the United States, and postulates a range of acquisition structures open to NASA. New research data is presented which specifically targets the interplay between acquisition and commonality. An assessment of practitioners' views on acquisition strategies for commonality examines three detailed case studies as well as summarizing a broad range of shorter interviews across NASA and DOD projects. Each of the postulated acquisition structures is evaluated against the NASA acquisition requirements and the synthesized commonality best practice. The evaluation demonstrates that current NASA acquisition strategies are geared towards commonality through reuse of existing components and systems, and forward-thinking investment in future commonality opportunities is unlikely. New strategies which involve less emphasis on competition between contractors in favor of greater continuity with experienced contractors are recommended to improve commonality. However, the commonality advantages from such strategies may be offset in a wider perspective by the costs of using such noncompetitive acquisition structures.
by Anthony C. Wicht.
S.M.
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Wachtel, Amanda M. (Amanda Marie). "A scalable methodology for modeling cities as systems of systems". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82418.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 144-146).
As cities evolve in size and complexity, their component systems become more interconnected. Comprehensive modeling and simulation is needed to capture interactions and correctly assess the impact of changes. This thesis presents a methodology for modeling cities from a systems of systems perspective. The framework supplies general modeling guidelines and key steps. Also addressed are the importance of stakeholder interactions, creating the model structure, using smart city sensor data, and applying the methodology to larger, traditional cities. As an initial step, four city modeling including CityNet, CityOne, Sim City 4, and SoSAT software programs were evaluated from both a user and mathematical perspective. From the assessments, a list was developed of features critical to successful city modeling software including visualization, a streamlined user interface, accurate mathematics, the ability to specify systems and attributes, and the ability to model interconnections between systems. SoSAT was selected as the modeling tool for the case study, which involved modeling the Army's Base Camp Integration Laboratory. A model of the camp's baseline configuration was built and the camp was simulated for 30 days with results recorded at one hour intervals. 100 trials were run with averaged results presented by time intervals and for the total simulation time. Results were presented at all levels of structural aggregation. Two sensitivity analyses were conducted to analyze the impact of maintenance personnel and the frequency of potable water deliveries. Adding or subtracting a maintenance person impacted the availability of the generator systems that were being serviced, in turn impacting the performance of the micro grid. Extending the time between deliveries by 24 and 48 hours revealed two systems experienced resource depletions. Lastly, two technology insertions cases were conducted to assess the impact of adding a laundry water reuse system (LWRS) and a solar powered hot water heater (SHWH). The LWRS provided 70% of the laundry system's water needs, significantly reducing dependency upon deliveries. The SHWH was expected to decrease electricity consumption and increase fuel consumption. However, the reduction in energy demand meant fewer generators were needed to power the micro grid and both electricity and fuel consumption decreased.
by Amanda M. Wachtel.
S.M.
40
Zeigler, Bernard P. "Contrasting emergence: In systems of systems and in social networks". SAGE PUBLICATIONS INC, 2017. http://hdl.handle.net/10150/621270.
Testo completoAbstract (sommario):
This article considers emergence in the context of systems of systems, examining the earlier proposed tri-layered architecture in some depth. In contrast with healthcare reform, a social media phenomenon, the emergence of topics in the Twitter user community, is shown not to satisfy a critical condition of the architecture. Nevertheless, detection of topic emergence is shown to offer insights into the design of Emergence Behavior Observers.
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Yamamoto, Kazusa. "Control of electromechanical systems, application on electric power steering systems". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT069/document.
Testo completoAbstract (sommario):
De nos jours, la plupart des véhicules sont équipés de Directions Assistées Electriques (DAE). Ce type de systèmes d'aide à la conduite permet de réduire les efforts que le conducteur doit fournir pour tourner les roues. Ainsi, grâce à un moteur électrique, la DAE applique un couple additionnel en accord avec le comportement du conducteur et la dynamique du véhicule. Il est donc nécessaire de développer une commande en couple basée en particulier sur le signal provenant d'un capteur mesurant le couple agissant au niveau de la barre de torsion (correspondant à une image du couple conducteur). Ce composant est donc essentiel au fonctionnement de la DAE. Or, une défaillance de ce capteur entraine le plus souvent une coupure de l'assistance, pouvant mener à un risque d'accidents. Au regard de la sécurité fonctionnelle, un développement d'un mode de sécurité est recommandé, par de plus en plus de constructeurs automobiles. D'autre part, le marché des équipementiers automobiles reste un secteur très concurrentiel où une baisse des coûts de production est un challenge constamment recherché afin de gagner de nouvelles parts de marchés. Cet aspect de réduction du nombre de capteurs et d'analyse de la dynamique du véhicule s'inscrit donc dans le prolongement de la stratégie de sécurité. Cette thèse, menée au sein de JTEKT Europe, aborde ces divers enjeux. Après une présentation des différents systèmes de directions assistés électriques, des modèles sont présentés pour être utilisés lors de la conception de lois de commande et d'estimateurs. Ensuite deux méthodes d'estimation du couple conducteur sujet aux perturbations de la route et aux bruits de mesures sont proposées : la première est un observateur proportionnel intégral (PI) à synthèse mixte $H_infty/H_2$, et la seconde une approche par filtrage $H_infty$. Puis plusieurs stratégies de commande sont proposées suivant deux cas de figures distincts, soit en utilisant un observateur PI qui estime les états du système et le couple conducteur (LQR, commande LPV par retour d'état), soit en faisant abstraction d'estimateur de couple conducteur (commande $H_infty$ par retour de sortie dynamique). Ce dernier aspect présente l'avantage de nécessiter moins de mesures que le précédent. Ces approches ont été validées en simulation et mises en œuvre sur un véhicule prototype où des résultats prometteurs ont été obtenusNowadays, modern vehicles are equipped with more and more driving assistance systems, among them Electric Power Steering (EPS) helps the driver to turn the wheels. Indeed, EPS provides through an electric motor, an additional torque according to the driver's behaviour and the vehicle's dynamics to reduce the amount of effort required to the driver. Therefore, a torque control is developed based on the torque sensor signal which measures in practice the torsion bar torque (corresponding to an image of the driver torque). Consequently, this component is essential to the functioning of EPS systems.Indeed, a torque sensor failure usually leads to shut-off the assistance which may increase the risk of accident. Regarding functional safety, a back-up mode is recommended and required by more and more car manufacturers. On the other hand, a major challenge for automotive suppliers is to reduce cost production in order to meet growing markets demands and manage in the competitive sector. This issue considering a reduction of sensors' numbers and analysis of vehicle's dynamics is therefore an extension of applying the safety strategy. This thesis, carried out within JTEKT Europe, addresses these various issues.After introducing an overview of the different EPS systems, some models used for the design of controllers and estimators are presented. Then, two methods to estimate the driver torque subject to road disturbances and noise measurements are proposed: the first is a proportional integral observer (PI) with mixed synthesis $H_infty / H_2 $, whereas the second is an $ H_infty $ filtering approach. Then, several control strategies are proposed according to two different cases, either by using a PI observer which estimates the system states and the driver torque (LQR, LPV feedback control) or by not taking into account the driver torque estimation ($ H_infty $dynamic output feedback control). This latter approach has the advantage to require less measurements than the previous one. These approaches have been validated in simulation and implemented on a prototype vehicle where promising results have been obtained
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Kumar, Prem. "Applications of superconducting magnetic energy storage systems in power systems". Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44118.
Testo completoAbstract (sommario):
A Superconducting Magnetic Energy Storage (SMES) system is a very efficient storage device capable of storing large amounts of energy. The primary applications it has been considered till now are load-leveling and system stabilization.This thesis explores new applications/benefits of SMES in power systems. Three areas have been identified.
â ¢ Using SMES in conjunction with PV systems.SMES because of their excellent dynamic response and PV being an intermittent source complement one another.A scheme for this hybrid system is developed and simulation done accordingly.
Using SMES in an Asynchronous link between Power Systems. SMES when used in a series configuration between two or more systems combines the benefits of asynchronous connection, interconnection and energy storage. A model of such a scheme has been developed and the control of such a scheme is demonstrated using the EMTP. The economic benefits of this scheme over pure power interchange, SMES operation alone and a battery/dc link is shown.
Improvement of transmission through the use of SMES. SMES when used for diurnal load leveling provides additional benefits like reduced transmission losses, reduced peak loading and more effective utilization of transmission facility, the impact of size and location on these benefits were studied, and if used as an asynchronous link provides power flow control.Master of Science
43
Scott, Michael Chase. "Viability of waste milk pasteurization systems for calf feeding systems". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/42348.
Testo completoAbstract (sommario):
The objective of this study was to determine amount and composition of waste milk (WM) generated by 13 dairy farms and to measure effectiveness of on-farm pasteurizers. Waste milk was sampled bi-weekly from three farms located in North Carolina (NC) for 28 weeks and twice from ten farms in California (CA) in June 2005 and Jan. 2006. Amount of waste milk generated ranged from 2.48 â 9.84 L/calf/d. Standard plate count (SPC) of waste milk before pasteurization averaged 17 million cfu/ml on NC farms and 1.6 million cfu/ml on CA farms. Pasteurizers failed to deactivate alkaline phosphatase in 16%, and <5% of the time in NC and CA. California WM had lower post pasteurized SPC (13,000 cfu/ml) than NC farms (430,000 cfu/ml).
A feeding trial was conducted to evaluate supplementing WM with 28% protein: 20% fat milk replacer (28:20) when WM is insufficient relative to calf demands. Treatment (TRT) 1 calves received M for 28d and then 28:20 until weaning at 56d. Treatment 2 calves received 28:20 for 28d and then milk until weaning. Treatment 3 calves received 28:20 for the entire period Four periods of time were evaluated; the total period, first four weeks (P1), transition period (TP), in which calves were switching diets, and until weaning (P2). Treatment 1 ADG was higher during TP as compared to TRT 2. Results demonstrated that similar growth rates through 8 weeks of age was achieved with either combination of M and 28:20 or only 28:20 fed on an isocaloric basis.Master of Science
44
Touati, Lyes. "Internet of things security : towards a robust interaction of systems of systems". Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2311/document.
Testo completoAbstract (sommario):
Cette thèse traite des problèmes et des défis de sécurité dans l’Internet des Objets (IdO). L’évolution de l’Internet classique vers l’Internet des Objets crée de nombreux challenges dans la manière de sécuriser les communications et soulève des problèmes liés au contraintes de l’internet des objets à savoir : objets à faibles ressources d’énergie et de calculs, hétérogénéité nuisant à l’interopérabilité des objets, taille du réseau de plus en plus grande, ... etc. En effet, Internet s’est développé d’un réseau d’ordinateurs personnels et de serveurs vers un immense réseau connectant des milliards d’objets intelligents communicants. Ces objets seront intégrés dans des systèmes complexes et utiliseront des capteurs et actionneurs pour observer et interagir avec leur environnement physique. Les exigences des interactions entre objets communicants en termes de sécurité dépendent du contexte qui évolue dans l’espace et le temps. Par conséquent, la définition de la politique de sécurité doit être adaptative et sensible au contexte. Un des problèmes auxquels nous nous sommes intéressés est le contrôle d’accès efficace à base de cryptographie d’attributs : « Attributes Based Encryption (ABE) ». Les schémas ABE (CP-ABE et KP-ABE) présentent plusieurs atouts pour l’implémentation d’un contrôle d’accès cryptographique. Par contre, ces schémas posent des défis opérationnels à cause de leurs complexités et leur surcoût élevé en termes de temps d’exécution et consommation énergétique. Pour pallier cet inconvénient, nous avons exploité l’hétérogénéité d’environnement Internet des Objets pour proposer des versions collaboratives et distribuées de ces schémas de contrôle d’accès cryptographique. Nos solutions réduisent considérablement le coût en termes d’énergie nécessaire à l’exécution. Le deuxième inconvénient des schémas ABE est l’inexistence de mécanismes efficaces de gestion de clés. Nous avons proposé des solutions pour le problème de révocation d’attributs dans le schéma CP-ABE, Ces solutions, en plus de leur efficacité, répondent à des exigences de sécurité différentes selon le cas d’applications. Nous avons proposé également, une solution à base de CP-ABE pour le problème du « grouping proof ». Le « grouping proof » consiste à fournir une preuve sur la coexistence, dans le temps et l’espace, d’un ensemble d’objets. Parmi les applications de notre solution, on peut citer le payement NFC et la sécurisation de l’accès aux locaux sensiblesIn this thesis, we deal with security challenges in the Internet of Things. The evolution of the Internet toward an Internet of Things created new challenges relating to the way to secure communications given the new constraints of IoT, namely: resource constrained objects, heterogeneity of network components, the huge size of the network, etc. Indeed, the Internet evolved from a network of computers and servers toward a huge network connecting billions of smart communicating objects. These objects will be integrated into complex systems and use sensors and actuators to observe and interact with their physical environment. The security requirements of the interactions between smart objects depend on the context which evolves in time and space. Consequently, the definition of the security policies should be adaptive and context-aware. In this thesis, we were interested in the problem of access control in IoT relying on Attribute based Encryption (ABE). Indeed, ABE schemes present many advantages in implementing a cryptographic fine-grained access control. However, these schemes raise many implementation challenges because of their complexity and high computation and energy overheads. To overcome this challenge, we leveraged the heterogeneity of IoT to develop collaborative and distributed versions of ABE schemes. Our solutions reduce remarkably the overhead in terms of energy consumption and computation. The second limitation of ABE schemes is the absence of efficient attribute/key revocation techniques. We have proposed batch based mechanisms for attribute/key revocation in CP-ABE. We demonstrated the efficiency of the proposed solutions through simulations. Finally, we have proposed a CP-ABE based solution for the problem of grouping proof. This problem consists of providing the proof that a set of objects are present simultaneously (same time and same location). The propose solution has many applications such as enforcing the security of NFC based payments and the access to sensitive locations
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Jones, Wyatt Elizabeth Ann. "A reliability-based measurement of interoperability for conceptual-level systems of systems". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52317.
Testo completoAbstract (sommario):
The increasing complexity of net-centric warfare requires assets to cooperate to achieve mission success. Such cooperation requires the integration of many heterogeneous systems into an interoperable system-of-systems (SoS). Interoperability can be considered a metric of an architecture, and must be understood as early as the conceptual design phase. This thesis approaches interoperability by first creating a general definition of interoperability, identifying factors that affect it, surveying existing models of interoperability, and identifying fields that can be leveraged to perform a measurement, including reliability theory and graph theory.
The main contribution of this thesis is the development of the Architectural Resource Transfer and Exchange Measurement of Interoperability for Systems of Systems, or ARTEMIS methodology. ARTEMIS first outlines a quantitative measurement of system pair interoperability using reliability in series and in parallel. This step incorporates operational requirements and the capabilities of the system pair. Next, a matrix of interoperability values for each resource exchange in an operational process is constructed. These matrices can be used to calculate the interoperability of a single resource exchange, IResource, and layered to generate a weighted adjacency matrix of the entire SoS. This matrix can be plugged in to a separate model to link interoperability with the mission performance of the system of systems. One output of the M&S is a single value ISoS that can be used to rank architecture alternatives based on their interoperability. This allows decision makers to narrow down a large design space quickly using interoperability as one of several criteria, such as cost, complexity, or risk.
A canonical problem was used to test the methodology. A discrete event simulation was constructed to model a small unmanned aircraft system performing a search and rescue mission. Experiments were performed to understand how changing the systems' interoperability affected the overall interoperability; how the resource transfer matrices were layered; and if the outputs could be calculated without time- and computationally-intensive stochastic modeling. It was found that although a series model of reliability could predict a range of IResource, M&S is required to provide exact values useful for ranking. Overall interoperability ISoS can be predicted using a weighted average of IResource, but the weights must be determined by M&S.
Because a single interoperability value based on performance is not unique to an architecture configuration, network analysis was conducted to assess further properties of a system of systems that may affect cost or vulnerability of the network. The eigenvalue-based Coefficient of Networked Effects (CNE) was assessed and found to be an appropriate measure of network complexity. Using the outputs of the discrete event simulation, it was found that networks with higher interoperability tended to have more networked effects. However, there was not enough correlation between the two metrics to use them interchangeably. ARTEMIS recommends that both metrics be used to assess a networked SoS.
This methodology is of extreme value to decision-makers by enabling trade studies at the SoS level that were not possible previously. It can provide decision-makers with information about an architecture and allow them to compare existing and potential systems of systems during the early phases of acquisition. This method is unique because it does not rely on qualitative assessments of technology maturity or adherence to standards. By enabling a rigorous, objective mathematical measurement of interoperability, decision-makers will better be able to select architecture alternatives that meet interoperability goals and fulfill future capability requirements.
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Pafford, Michael E., e Lyle V. Munn. "A comparison of information systems and non-information systems personnel working in non-information systems organizational departments". Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/24277.
Testo completoAbstract (sommario):
A survey was conducted to investigate motivational and satisfaction differences between Information Systems (IS) and non-IS personnel working in various non-IS organizational departments. The motivational factors of Motivating Potential Score (MPS), Growth Need Strength (GNS), Social Need Strength (SNS), Average Psychological Score (APS), and Overall Satisfaction Score (OSS) were measured. Control for occupational group differences was achieved by classifying survey respondents into one of two job categories: Managerial or Professional/Technical. Significant differences were found in the GNS scores and SNSs of the two job categories. Several implications of the research findings are discussed and recommendations are made with respect to future studies.
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Elders, Ian Michael. "The use of intelligent systems in control and management of power systems". Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248724.
Testo completo
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Argunsah, Bayram Hande. "Biomechanics of Prosthetic Knee Systems: Role of Dampening and Energy Storage Systems". Cleveland State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=csu1371689387.
Testo completo
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Ahmad, Bashar I. "Applications of nonuniform sampling in wideband multichannel communication systems". Thesis, University of Westminster, 2011. https://westminsterresearch.westminster.ac.uk/item/8zwv9/applications-of-nonuniform-sampling-in-wideband-multichannel-communication-systems.
Testo completoAbstract (sommario):
This research is an investigation into utilising randomised sampling in communication systems to ease the sampling rate requirements of digitally processing narrowband signals residing within a wide range of overseen frequencies. By harnessing the aliasing suppression capabilities of such sampling schemes, it is shown that certain processing tasks, namely spectrum sensing, can be performed at significantly low sampling rates compared to those demanded by uniform-sampling-based digital signal processing. The latter imposes sampling frequencies of at least twice the monitored bandwidth regardless of the spectral activity within. Aliasing can otherwise result in irresolvable processing problems, as the spectral support of the present signal is a priori unknown. Lower sampling rates exploit the processing module(s) resources (such as power) more efficiently and avoid the possible need for premium specialised high-cost DSP, especially if the handled bandwidth is considerably wide. A number of randomised sampling schemes are examined and appropriate spectral analysis tools are used to furnish their salient features. The adopted periodogram-type estimators are tailored to each of the schemes and their statistical characteristics are assessed for stationary, and cyclostationary signals. Their ability to alleviate the bandwidth limitation of uniform sampling is demonstrated and the smeared-aliasing defect that accompanies randomised sampling is also quantified. In employing the aforementioned analysis tools a novel wideband spectrum sensing approach is introduced. It permits the simultaneous sensing of a number of nonoverlapping spectral subbands constituting a wide range of monitored frequencies. The operational sampling rates of the sensing procedure are not limited or dictated by the overseen bandwidth antithetical to uniform-sampling-based techniques. Prescriptive guidelines are developed to ensure that the proposed technique satisfies certain detection probabilities predefined by the user. These recommendations address the trade-off between the required sampling rate and the length of the signal observation window (sensing time) in a given scenario. Various aspects of the introduced multiband spectrum sensing approach are investigated and its applicability highlighted.
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Abdel-Hadi, Yasser Abdel-Fattah. "Development of optical concentrator systems for directly solar pumped laser systems". [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978527569.
Testo completo