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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.
1

Parallélisation de simulateur DEVS par métamodélisation et transformation de modèle / DEVS simulator parallelization by metamodeling and model transformation

Togo, Hamidou 23 December 2015 (has links)
Cette thèse propose une approche d’ingénierie consistant à paralléliser des simulateurs DEVS existants, sans être obligé de modifier les algorithmes de l’implémentation initiale, mais en injectant des composants additionnels adaptés au protocole de communication intercomposants en vigueur. Les algorithmes de simulation de ces nouveaux composants appelés « Manteaux », sont définis. Une démarche d’ingénierie permettant de systématiser le passage d’une implémentation à sa contrepartie parallèle et distribuée est ensuite proposée. Cette démarche s’appuie sur les principes de méta modélisation et de transformation de modèles inspirés de l’Ingénierie Dirigée par les Modèles (IDM). Sa généricité en garantit la réutilisabilité avec tout simulateur séquentiel DEVS. / This thesis proposes an engineering approach to parallelize existing DEVS simulators without having to modify the algorithms of the initial implementation, but by injecting additional components suitable for inter-component communication protocol into force. The simulation algorithms of these new components called "Coats" are defined.An engineering approach to systematize the passage from one implementation to its counterpart parallel and distributed is then proposed. This approach is based on metamodeling and models transformation principles inspired of Model Driven Engineering (MDE). Its genericity guarantees the reusability with any sequential DEVS simulator.
2

Challenges in International Joint Venture of Clothing Retail Industry : Marks & Spencer in Taiwan

Santosa, Budianto 19 June 2010 (has links)
When deciding to internationalize, companies face the need to develop a foreign market strategy and a foreign market expansion strategy especially when the foreign country has very different culture from home country. Most research of company process of internationalization nevertheless is based on entry mode and mostly successful businesses. Here, the failure of joint venture between Marks and Spencer (M&S), one of the biggest of British Retail Company and Uni-President Corporation, the biggest food and drink enterprise in Taiwan is examined. Its recent large-scale withdrawal from such activity is also measured to some extend of theories about internationalization and marketing failure. The qualitative method and a case study were carried out. In addition, in-depth interviews with Uni-President representative, M&S Visual Display Manager and two groups of M&S customers and non M&S customers are the primary resources of data. The research suggested the joint venture between the two companies created many problems due to two extremely different cultures and lack of understanding of the local market. M&S marketing strategy did not draw Taiwanese consumers¡¦ interest. The products and stores are not attractive or follow the fashion trend. The promotion also did not appeal the consumers. The complexities of Taiwanese consumers¡¦ perspective toward M&S brand and country-of-origin, cultural differences and the potential reasons of M&S exited Taiwan are as well emphasized.
3

Lithium-Ion Battery Electrolyte Evaporation

Dylan Michael Poe (15348418) 29 April 2023 (has links)
<p> Energy storage has received much attention due to the increasing use of energy, especially renewable energy. Lithium-ion batteries have great characteristics for electrical energy storage. Higher specific energy density, cycle life, cell voltage, shorter charge times gives lithium-ion batteries favorable energy storage characteristics over other battery chemistries. Although lithium-ion batteries are increasing in use for electrical energy storage, their safety still poses an engineering problem. When lithium-ion batteries are abused, they can enter thermal runaway. This event is dangerous as it can eject hot gases and shrapnel. Previous studies focused on different aspects of thermal runaway, for example, heat generation from chemical reactions, propagation to other cells, and the physics of gas venting. One phenomenon that has not received much attention is the evaporation of the electrolyte out of a failed lithium-ion battery. Understanding the effect of electrolyte evaporation is key to having a more complete understanding of thermal runaway. In this thesis, the physics of electrolyte evaporation is studied with the purpose of developing more accurate thermal abuse models. An evaporation model was developed, based on porous drying theory and a 1-D liquid diffusion process. Experiments were conducted to identify the liquid diffusion coefficient which governs the rate of electrolyte transport within the porous separator within the battery. The 1-D liquid diffusion model was then implemented into an existing thermal abuse model and exercised for a typical oven test scenario. Results showed that the physics-based evaporation model resulted in excellent agreement with experimental data at different oven temperatures.</p>
4

DEVELOPMENT OF AN OPEN-SOURCE TOOLBOX FOR DESIGN AND ANALYSIS OF ACTIVE DEBRIS REMEDIATION ARCHITECTURES

Joshua David Fitch (16360641) 15 June 2023 (has links)
<p> Orbital Debris is a growing challenge for the Space Industry. The increasing density of derelict objects in high-value orbital regimes is resulting in more conjunction warnings and break-up events with cascading repercussions on active satellites and spacecraft. The recent rapid growth of the commercial space industry, in particular proliferated satellite constellations, has placed orbital debris remediation at the forefront of Space Industry efforts. The need to remove existing debris, combined with a growing demand for active satellite life extension services, has created an emerging market for space logistics, in particular spacecraft capable of rendezvous and docking, orbital refueling, debris deorbiting, or object relocation. This market has seen numerous companies emerge with multi-purpose on-orbit servicing platforms. This ecosystem poses technological, economical, and policy questions to decision-makers looking to acquire platforms or invest in technologies and requires a System-of-Systems approach to determine mission and system concepts of merit. An open-source modeling, analysis, and simulation software toolbox has been developed which enables rapid early-stage analysis and design of diverse fleets of on-orbit servicing platforms, with a specific emphasis on active debris removal applications. The toolbox provides fetching and processing of real-time orbital catalog data, clustering and scoring of high-value debris targets, flexible and efficient multi-vehicle multi-objective time-varying routing optimization, and fleet-level lifecycle cost estimation. The toolbox is applied to a diverse sample of promising commercial platforms to enable government decision-makers to make sound investment and acquisition decisions to support the development of ADR technologies, missions, and companies. </p>
5

An Agile Roadmap for Live, Virtual and Constructive-Integrating Training Architecture (LVC-ITA): A Case Study Using a Component based Integrated Simulation Engine

Park, Tae Woong 01 January 2015 (has links)
Conducting seamless Live Virtual Constructive (LVC) simulation remains the most challenging issue of Modeling and Simulation (M&S). There is a lack of interoperability, limited reuse and loose integration between the Live, Virtual and/or Constructive assets across multiple Standard Simulation Architectures (SSAs). There have been various theoretical research endeavors about solving these problems but their solutions resulted in complex and inflexible integration, long user-usage time and high cost for LVC simulation. The goal of this research is to provide an Agile Roadmap for the Live Virtual Constructive-Integrating Training Architecture (LVC-ITA) that will address the above problems and introduce interoperable LVC simulation. Therefore, this research describes how the newest M&S technologies can be utilized for LVC simulation interoperability and integration. Then, we will examine the optimal procedure to develop an agile roadmap for the LVC-ITA. In addition, this research illustrated a case study using an Adaptive distributed parallel Simulation environment for Interoperable and reusable Model (AddSIM) that is a component based integrated simulation engine. The agile roadmap of the LVC-ITA that reflects the lessons learned from the case study will contribute to guide M&S communities to an efficient path to increase interaction of M&S simulation across systems.
6

TELEMETRY PROCESSING SYSTEMS DESIGN TRENDS

Yates, James William 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / Current changes in the way that large flight test systems are utilized have affected the industry’s methodology in both the early design phases and in the implementation of nextgeneration hardware and software. The reduction of available RF spectrum, the implementation of packet telemetry methods and systems, and a desire to implement commercial-off-the-shelf (COTS) hardware are only some of the considerations that telemetry systems integrators and product houses have to face. This paper describes how test methodology changes affect current large systems design at both government test ranges and at airframe/missile manufacturer test facilities. In addition, consideration is given to the area of increased processing power as it affects hardware and software design, the leveraging of such current and future telecommunications technology as network switch technology and compression, cross utilization, standardized technology, and the movement toward platform-independent software.
7

USING REINFORCEMENT LEARNING FOR ACTIVE SHOOTER MITIGATION

Robert Eugen Bott (11791199) 20 December 2021 (has links)
This dissertation investigates the value of deep reinforcement learning (DRL) within an agent-based model (ABM) of a large open-air venue. The intent is to reduce civilian casualties in an active shooting incident (ASI). There has been a steady increase of ASIs in the United States of America for over 20 years, and some of the most casualty-producing events have been in open spaces and open-air venues. More research should be conducted within the field to help discover policies that can mitigate the threat of a shooter in extremis. This study uses the concept of dynamic signage, controlled by a DRL policy, to guide civilians away from the threat and toward a safe exit in the modeled environment. It was found that a well-trained DRL policy can significantly reduce civilian casualties as compared to baseline scenarios. Further, the DRL policy can assist decision makers in determining how many signs to use in an environment and where to place them. Finally, research using DRL in the ASI space can yield systems and policies that will help reduce the impact of active shooters during an incident.

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