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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

MaSTA: a text-based machine learning approach for systems-of-systems in the big data context / MaSTA: uma abordagem de aprendizado de máquina orientado a textos para sistemas-de-sistemas no contexto de big data

Bianchi, Thiago 11 April 2019 (has links)
Systems-of-systems (SoS) have gained a very important status in industry and academia as an answer to the growing complexity of software-intensive systems. SoS are particular in the sense that their capabilities transcend the mere sum of the capacities of their diverse independent constituents. In parallel, the current growth in the amount of data collected in different formats is impressive and imposes a considerable challenge for researchers and professionals, characterizing hence the Big Data context. In this scenario, Machine Learning techniques have been increasingly explored to analyze and extract relevant knowledge from such data. SoS have also generated a large amount of data and text information and, in many situations, users of SoS need to manually register unstructured, critical texts, e.g., work orders and service requests, and also need to map them to structured information. Besides that, these are repetitive, time-/effort-consuming, and even error-prone tasks. The main objective of this Thesis is to present MaSTA, an approach composed of an innovative classification method to infer classifiers from large textual collections and an evaluation method that measures the reliability and performance levels of such classifiers. To evaluate the effectiveness of MaSTA, we conducted an experiment with a commercial SoS used by large companies that provided us four datasets containing near one million records related with three classification tasks. As a result, this experiment indicated that MaSTA is capable of automatically classifying the documents and also improve the user assertiveness by reducing the list of possible classifications. Moreover, this experiment indicated that MaSTA is a scalable solution for the Big Data scenarios in which document collections have hundreds of thousands (even millions) of documents, even produced by different constituents of an SoS. / Sistemas-de-sistemas (SoS) conquistaram um status muito importante na indústria e na academia como uma resposta à crescente complexidade dos sistemas intensivos de software. SoS são particulares no sentido de que suas capacidades transcendem a mera soma das capacidades de seus diversos constituintes independentes. Paralelamente, o crescimento atual na quantidade de dados coletados em diferentes formatos é impressionante e impõe um desafio considerável para pesquisadores e profissionais, caracterizando consequentemente o contexto de Big Data. Nesse cenário, técnicas de Aprendizado de Máquina têm sido cada vez mais exploradas para analisar e extrair conhecimento relevante de tais dados. SoS também têm gerado uma grande quantidade de dados e informações de texto e, em muitas situações, os usuários do SoS precisam registrar manualmente textos críticos não estruturados, por exemplo, ordens de serviço e solicitações de serviço, e também precisam mapeá-los para informações estruturadas. Além disso, essas tarefas são repetitivas, demoradas, e até mesmo propensas a erros. O principal objetivo desta Tese é apresentar o MaSTA, uma abordagem composta por um método de classificação inovador para inferir classificadores a partir de grandes coleções de texto e um método de avaliação que mensura os níveis de confiabilidade e desempenho desses classificadores. Para avaliar a eficácia do MaSTA, nós conduzimos um experimento com um SoS comercial utilizado por grandes empresas que nos forneceram quatro conjuntos de dados contendo quase um milhão de registros relacionados com três tarefas de classificação. Como resultado, esse experimento indicou que o MaSTA é capaz de classificar automaticamente os documentos e também melhorar a assertividade do usuário através da redução da lista de possíveis classificações. Além disso, esse experimento indicou que o MaSTA é uma solução escalável para os cenários de Big Data, nos quais as coleções de documentos têm centenas de milhares (até milhões) de documentos, até mesmo produzidos por diferentes constituintes de um SoS.
52

A multi-level trade-off methodology for analyzing collaborative system-of-system alternatives

Molino, Nicholas Anthony 08 June 2015 (has links)
As unmanned vehicle capabilities have matured, the design and development of autonomous collaborative Systems-of-Systems (SoS) has gained increased attention. This has been motivated by the indication that significant improvements in overall effectiveness may be possible by employing many systems in cooperation with one another. However, as the potential combinations of vehicles, subsystems, and operational concepts becomes increasingly large, a systematic approach is needed for designing and analyzing alternatives. Furthermore, the discrete nature of the problem can cause variations in effectiveness that are counter-intuitive, such as a point of diminishing returns as the number of systems grows. Systems-of-systems are hierarchical in nature, consisting of top-level mission requirements that are decomposed into system- and subsystem-level performance measures. The overarching research objectives of this dissertation are to show that the analysis of alternatives should be performed at varying levels of the SoS hierarchy and to provide novel means for performing those analyses. In particular, it has been postulated that a formulation built on an energy-based approach to multi-level analysis of SoS components will enable more accurate and transparent subsystem and system trade-offs. Various steps of the design process are established and argued for or against, and significant focus is placed on the analysis of alternatives. The foundation of the new method is laid on structured SoS engineering principles. The full substance comes together by incorporating unique aspects developed within this dissertation. A new virtual experimentation approach is presented for creating sensor performance representations that are functions of vehicle operations. The sonar equation is used as a baseline sensor model for comparison against the new virtual experimentation method. Dozens of forward-looking and side-scan sonar experiments are designed, and data is provided to show the extent to which typical sensor modeling over-predicts performance without vehicle operations considered. In addition, comparisons are made between possible representations of vehicle performance. An underwater vehicle sizing and synthesis process is developed to enable comparisons between system-level component modeling approaches. The experiments attest to significant gaps in accuracy when performing sensor and operational trade-offs without energy-based modeling of the collaborative vehicles. Finally, a heuristic path-planning algorithm is formulated, and mixed-integer linear programming is used to choose between alternative SoS designs. The developed method is demonstrated through a representative example problem: a group of unmanned underwater vehicles (UUVs) operating in a collaborative fashion to search for underwater objects. The example scenario provides an application for illustrating the phenomenon discussed in regards to the analysis of alternatives of collaborative SoS. The significance of providing more or less analytic detail is traced and the effect on mission requirements is quantified. Counter-intuitive results are highlighted, such as the observation that the increased energy required for systems to effectively collaborate can often out-weigh the benefits gained in overall mission effectiveness.
53

A system-of-systems modeling methodology for strategic general aviation design decision-making

Won, Henry Thome 17 November 2008 (has links)
A methodology for modeling general aviation transportation systems from a system of systems perspective is presented. The completed framework aids the conceptual design process by providing capability-based metrics to the design engineer, as opposed to the traditional performance and cost, system-level metrics. The methodology is applied to two example problems representing promising future general aviation aircraft: the general aviation piston (GAP) and jet (GAJ). Results are presented in an array of formats, and the decision-making strategies that are now apparent in light of the capability-based metrics are described. The findings suggest that the system of systems framework might act as an analytical surrogate to the conventional problem definition process, providing indications of market preferences when that information is not immediately available through the conventional means. Implementation of this methodology can afford engineers a more autonomous perspective in the concept exploration process, providing dynamic feedback about a design's potential success in specific market segments. The method also has potential to strengthen the connection between design and business departments, as well as between manufacturers, service providers, and infrastructure planners - bringing information about how the respective systems interact, and what might be done to improve synergism of systems.
54

Les rôles : médiateurs dynamiques entre modèles système et modèles de simulation / Roles : dynamic mediators between system models and simulation models

Schneider, Jean-Philippe 25 November 2015 (has links)
Les systèmes actuels tendent à être intégrés les uns avec les autres. Mais cette intégration n'est pas forcément prévue à l'origine du système. Cette tendance créée des systèmes de systèmes. Un système de système de systèmes est un système constitué de systèmes qui sont gérés par des équipes indépendantes, qui sont fonctionnellement indépendants, qui collaborent, qui évoluent et qui sont géographiquement distribués. La communication entre les différentes équipes facilite la conception d'un système de systèmes. Cette communication peut être réalisée par l'utilisation de modèles et de simulation. Cependant, la modélisation du système de systèmes et la modélisation des simulations ne reposent pas sur les mêmes langages. Pour assurer la cohérence des modèles, il faut pouvoir créer les modèles de simulation à partir des modèles système. Cependant, il faut tenir compte des contraintes liées aux propriétés des systèmes de systèmes. Il faut être capable de manipuler des modèles systèmes réalisés dans des langages différents, de réaliser des simulations de natures différentes et suivre les évolutions des langages de modélisation et des outils de simulation. Pour répondre à ces problématiques, nous avons défini l'environnement Role4AII pour la manipulation de modèles systèmes réalisés dans des langages hétérogènes. Role4AII est basé sur la notion de rôles. Les rôles permettent de créer des simulations en accédant aux informations contenues dans des éléments de modèles indépendamment de leur type. Role4AII est capable de prendre en entrée des modèles sérialisés par différents outils grâce à l'utilisation de parsers combinateurs. Ces derniers apportent modularité et extensibilité aux fonctionnalités d'import. L'environnement Role4AII a été utilisé sur un exemple de système de systèmes : l'observatoire sous-marin MeDON. / Current Systems tend to become integrated with each others. However, this intégration may not be designed for the System. This trend raises the concept of System of Systems. A System of Systems is a System made of Systems which are managed independently, functionaly independent, collaborating, evolving and geographically distributed. The communication among the different teams eases the design of the System of Systems. This communication may be made through the use of models and simulation.However, System of Systems models and simulation models do not rely on the same modeling languages. In order to ensure coherency between the two types of models, simulation models should be obtained from System models. But this approach should take into account the constraints coming from the properties of System of Systems. System models made in different modeling languages should be handled, simulation of different kinds should be generated and the evolution of both modeling languages and simulation tools should be managed.In order to tackle these issues, we defined the Role4AII environment to manipulate System models made in heterogeneous modeling languages. Role4AII is based on the concept of rôles. Rôles enable to create simulations by accessing to information stored in model éléments despite their types differences. Role4AII is able to take as input serialized models from different modeling tools by using parser combinators. Parser combinators bring modularity and extensibility to the import features. Role4AII has been used on a System of System example: the MeDON seafloor observatory.
55

System-of-systems modeling and simulation for the risk analysis of industrial installations and critical infrastructures / Simulation et modélisation de système des systèmes pour l’analyse des risques des installations industrielles et des infrastructures critiques

Ferrario, Elisa 10 September 2014 (has links)
Le travail de recherche propose et développe un cadre de système des systèmes (SdS) pour l’analyse de risques des installations industrielles et des infrastructures critiques. Les méthodes pour la représentation, la modélisation et la simulation d’un système sont développées pour identifier les particularités du SdS quant à leur vulnérabilité et leur résilience physique à des défaillances aléatoires et risques naturels. Plusieurs techniques de représentation, telles que l’arbre de défaillances, le Muir Web, la modélisation hiérarchique, le Goal Tree Success Tree – Dynamic Master Logic Diagram, sont étudiées et approfondies depuis l’origine pour s’adapter aux objectifs de l’analyse de SdS. Une méthode de représentation est développée ex novo, à savoir, le graphe hiérarchique. Dans ces cadres de représentation, des états binaires et multiples sont utilisés pour modéliser les performances des SdS à analyser. La simulation Monte Carlo et l’analyse d’intervalle sont combinées pour évaluer quantitativement des modèles de SdS en présence d’incertitude (due à la variabilité naturelle d’un phénomène ou au manque d’information). La mise en oeuvre de ces approches est illustrée dans deux domaines d’application : l’évaluation du risque d’événements externes et la vulnérabilité d’infrastructures critiques. / This thesis propounds and develops a system-of-systems (SoS) framework for the risk analysis of industrial installations and critical infrastructures. System representation, modeling and simulation methods are developed to capture the peculiar features of SoS, with respect to their vulnerability and physical resilience to random failures and natural hazards. Several representation techniques of literature, i.e., Fault Tree, Muir Web, Hierarchical Modeling, Goal Tree Success Tree – Dynamic Master Logic Diagram, are explored and originally extended/tailored to fit the purpose of SoS analysis. One representation method is developed ex-novo, namely the Hierarchical Graph. Within these representation frameworks, binary and multiple states are used to model the performances of the SoS under analysis. Monte Carlo simulation and interval analysis are combined for the quantitative evaluation of the SoS models in presence of uncertainty (due to both randomness and lack of knowledge). Examples of analyses are carried out within two application areas: external event risk assessment and vulnerability of critical infrastructures.
56

A System-of-Systems Framework for Assessment of Resilience in Complex Construction Projects

Zhu, Jin 14 July 2016 (has links)
Uncertainty is a major reason of low efficiency in construction projects. Traditional approaches in dealing with uncertainty in projects focus on risk identification, mitigation, and transfer. These risk-based approaches may protect projects from identified risks. However, they cannot ensure the success of projects in environments with deep uncertainty. Hence, there is a need for a paradigm shift from risk-based to resilience-based approaches. A resilience-based approach focuses on enhancing project resilience as a capability to cope with known and unknown uncertainty. The objective of this research is to fill the knowledge gap and create the theory of resilience in the context of complex construction project systems. A simulation approach for theory development was adopted in this research. The simulation framework was developed based on theoretical elements from complex systems and network science. In the simulation framework, complex projects are conceptualized as meta-networks composed of four types of nodes: human agents, information, resources, and tasks. The impacts of uncertainty are translated into perturbations in nodes and links in project meta-networks. Accordingly, project resilience is investigated based on two components: project vulnerability (i.e., the decrease in meta-network efficiency under uncertainty) and adaptive capacity (i.e., the speed and capability to recover from uncertainty). Simulation experiments were conducted using the proposed framework and data collected from three complex commercial construction project cases. Different scenarios related to uncertainty-induced perturbations and planning strategies in the cases were evaluated through the use of Monte Carlo simulation. Three sets of theoretical constructs related to project resilience were identified from the simulation results: (1) Project vulnerability is positively correlated with exposure to uncertainty and project complexity; (2) Project resilience is positively correlated with adaptive capacity, and negatively correlated with vulnerability; (3) Different planning strategies affect project resilience either by changing the level of vulnerability or adaptive capacity. The effectiveness of a planning strategy is different in different projects. Also, there is a diminishing effect in effectiveness when adopting multiple planning strategies. The results highlighted the significance of the proposed framework in providing a better understanding of project resilience and facilitating predictive assessment and proactive management of project performance under uncertainty.
57

Bridging software engineering gaps towards system of systems development / Preenchendo lacunas da Engenharia de Software rumo ao desenvolvimento de sistema de sistemas

Marcelo Augusto Ramos 07 May 2014 (has links)
While there is a growing recognition of the importance of System of Systems (SoS), there is still little agreement on just what they are or on by what principles they should be constructed. Actually, there are numerous SoS definitions in the literature. The difficulty in specifying what are the constituent systems, what they are supposed to do, and how they are going to do it frequently lead SoS initiatives to complete failures. Guided by a sample SoS that comprises all the distinguishing SoS characteristics and a generic SoS Engineering (SoSE) process, this thesis explores the SoS development from different Software Engineering (SE) perspectives that include requirements, analysis, design, and reengineering. For the Requirements Engineering (RE), we propose a scene-based RE approach to describe the SoS progressively as an arrangement of elementary but meaningful related behaviors named scenes. The objective is making easier the description and the understanding of the SoS dynamism. For the analysis, we propose extensions to statecharts to visually improve the modeling of systems interactions. They are symbolic notations that result from an analogy with multi-layer Printed Circuit Boards (PCB). The resulting diagrams are named PCBstatecharts. For the design, we propose an extension to the conventional SPLE process in such a way that SPL can become a natural source of SoS members. Domain engineering is extended to deliver components able to share abilities in SoS environments. Then, application engineers can design families of products that comply with different SoS requirements and still improve their products using the abilities of other SoS members. For the reengineering, we propose an approach extension to evolve legacy systems to SPL and then to SoS members. We demonstrate that when legacy systems are reengineered properly, they can share useful abilities, work cooperatively, and compose SoS / Apesar do crescente reconheciimento da importância de Sistemas de Sistemas (SoS) ainda não há um consenso sobre o que eles são um para que princípios devem ser construídos. De fato, existem várias definições de SoS na literatura. A dificuldade de especificar quais são os sistemas constituintes, as suas tarefas e como eles irão realizá-las frequentemente conduzem iniciativas de SoS ao completo fracasso. Guiados por um exemplo que inclui todas as características distintas de um SoS e um processo genérico de engenharia de SoS (SoSE), esta tese explora o desenvolvimento de SoS a partir de diferentes perspectivas da engenharia de software (SE), que incluem requisitos, análise, projeto e reengenharia. Para a engenharia de requisitos (RE) é proposta uma abordagem para descrever progressivamente um SoS como um arranjo de comportamentos mais simples, porém significativos, denominados \'cenas\'. O objetivo é facilitar a descrição e o entendimento do SoS e seu dinamismo. Para a análise, propõe-se as extensões de statecharts para melhorar a modelagem das interações entre sistemas. Elas são notações simbólicas que resultam de uma analogia com placas de circuito impresso multi camadas (PCB). Os diagramas resultantes são denominados PCB-statecharts. Para o projeto, é proposta uma extensão para o processo convencional de engenharia de linha de produtos (SPLE), de tal forma que linhas de produto (SPL) possam se tornar uma fonte natural de membros para SoS. A engenharia de domínio é estendida para prover componentes capazes de compartilhar habilidades em ambientes de SoS. Desta forma, engenheiros de aplicação podem projetar famílias de produtos complacentes com diferentes requisitos de SoS e ainda melhorar seus produtos usando habilidades de outros membros de um SoS. Para a reengenharia propõe-se extensão de uma abordagem existente para evoluir legados para SPL e depois para membros de um SoS. O objetivo é demonstrar que quando sistemas legados são tratados apropriadamente, eles podem compartilhar habilidades úteis, trabalhar de maneira cooperativa e compor SoS
58

Ontology Information Processing toMatrix-Based Approaches for ConceptualDesign

Karpur, Anoop January 2021 (has links)
This thesis aims to develop a methodology to translate an ontology to a matrixbased methods that is case independent. In the larger picture this is one of manycomplexities in systems engineering approach. The focus in this work is in the domainof conceptual design, hence, matrix based methods that are most suitable for it areinvestigated. The flexible nature of the ontology always allows for expansion withnew information about the concepts, and from that perspective a parsing scriptwas developed to extract information from the ontology, it was also designed to beflexible. The script can be used to extract any desired type of information by alteringa few keywords as inputs. The advantage is that the same structure of the script canbe used to extract information from many different ontologies.Using this method the matrices relevant for conceptual design were formulated.These matrices were further compared to each other. Also, a few recommendationswere given for the improvement of the method to adapt towards high fidelity. Thecurrent method is capable of solving problems with low fidelity, however this formsa basis to expand the method to high fidelity problems.
59

Systems Geometry: A Methodology For Analyzing Emergent System Of Systems Behaviors

Bouwens, Christina 01 January 2013 (has links)
Recent advancements in technology have led to the increased use of integrated ‘systems of systems’ (SoS) which link together independently developed and usable capabilities into an integrated system that exhibits new, emergent capabilities. However, the resulting SoS is often not well understood, where secondary and tertiary effects of tying systems together are often unpredictable and present severe consequences. The complexities of the composed system stem not only from system integration, but from a broad range of areas such as the competing objectives of different constituent system stakeholders, mismatched requirements from multiple process models, and architectures and interface approaches that are incompatible on multiple levels. While successful SoS development has proven to be a valuable tool for a wide range of applications, there are significant problems that remain with the development of such systems that need to be addressed during the early stages of engineering development within such environments. The purpose of this research is to define and demonstrate a methodology called Systems Geometry (SG) for analyzing SoS in the early stages of development to identify areas of potential unintended emergent behaviors as candidates for the employment of risk management strategies. SG focuses on three dimensions of interest when planning the development of a SoS: operational, functional, and technical. For Department of Defense (DoD) SoS, the operational dimension addresses the warfighter environment and includes characteristics such as mission threads and related command and control or simulation activities required to support the mission. The functional dimension highlights different roles associated with the development and use of the SoS, which could include a participant warfighter using the system, an analyst collecting data iv for system evaluation, or an infrastructure engineer working to keep the SoS infrastructure operational to support the users. Each dimension can be analyzed to understand roles, interfaces and activities. Cross-dimensional effects are of particular interest since such effects are less detectable and generally not addressed with conventional systems engineering (SE) methods. The literature review and the results of this study have identified key characteristics or dimensions that should be examined during SoS analysis and design. Although many methods exist for exploring system dimensions, there is a gap in techniques to explore cross-dimensional interactions and their effect on emergent SoS behaviors. The study has resulted in a methodology for capturing dimensional information and recommended analytical methods for intra-dimensional as well as cross-dimensional analysis. A problem-based approach to the system analysis is recommended combined with the application of matrix methods, network analysis and modeling techniques to provide intra- and cross-dimensional insight. The results of this research are applicable to a variety of socio-technical SoS analyses with applications in analysis, experimentation, test and evaluation and training
60

Architectural approach for Autonomous System of Systems Interoperability

Paniagua, Cristina January 2019 (has links)
The current technological environment is evolving increasingly fast, and the development of new devices, technologies, and architectures has opened an emergent era where the digital and physical world work together. The implementation and use of systems based on a service-oriented architecture (SOA) in conjunction with the Internet of Things (IoT) and cyberphysical systems (CPS) have been extended during the last decades in numerous scenarios in industry and other domains. However, some of the major barriers to this approach are the lack of interoperability and the amount of engineering effort required for their integration.   The research presented in this thesis targets issues related to digitalization and automation. It is framed by the Industry 4.0 paradigm, which promotes the rise of efficiency and sustainability on industrial production. The interoperability between heterogeneous systems and different domains is one of the main challenges of Industry 4.0. The quest for solutions that help to increase interoperability is an important part of this research.   This thesis proposes a set of architectural design principles and tools in order to reduce engineering effort by means of finding solutions that enable autonomous integration and increase interoperability without human intervention. The research is focused on the IoT field, taking into account resource-constrained devices, system of systems integration, and data models.   A detailed investigation of various interoperability mismatch problems is presented in this thesis. The proposed solution is an adapter system that can aid in the generation of new service consumer interfaces at both compile-time and run-time. The proposed approach requires a new point of view in the service description field that can provide a holistic description of the information required for the generation of consumer interfaces. In addition, aspects related to interoperability, such as the multiple IoT frameworks in the current market, naming conventions, syntactic modeling and translation, and security, are also partially analyzed.   On a separate track, service composition in resource-constrained devices  is analyzed in terms of latency, using the orchestration provided by the Arrowhead Framework.

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