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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

A general inspection-repair-replacement model for systems with unobservable states.

January 1996 (has links)
by Siu-Keung Wan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 69-70). / Chapter Chapter 1 --- Introduction and Review / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Review --- p.3 / Chapter Chapter 2 --- A general IRR model for a system with unobservable states / Chapter 2.1 --- Model and assumptions --- p.8 / Chapter 2.2 --- Long-run average cost per unit time incurred in a replacement cycle --- p.14 / Chapter Chapter 3 --- The Algorithm / Chapter 3.1 --- The key point and the local turning point of the average cost --- p.16 / Chapter 3.2 --- A finite algorithm --- p.23 / Chapter Chapter 4 --- Numerical examples and sensitivity analysis with discussion / Chapter 4.1 --- Weibull Distribution Case --- p.25 / Chapter 4.2 --- Gamma Distribution Case --- p.28 / Chapter 4.3 --- Exponential Distribution Case --- p.30 / Chapter 4.4 --- Sensitivity analysis --- p.32 / Chapter 4.5 --- Conclusion and further development --- p.38 / Figures --- p.40 / Tables --- p.46 / References --- p.69
2

Optimal availability allocation in series-parallel maintained systems

Lie, Chang Hoon January 2011 (has links)
Digitized by Kansas Correctional Industries
3

Can the use of RPM be justified without services? / Can the use of resale price maintenance be justified without services? / CUHK electronic theses & dissertations collection

January 2015 (has links)
Regarding most law cases of resale price maintenance (RPM), non-pricing strategies (mostly termed ”services”) that were first brought by Tesler (1960) are usually applied to justify RPM. However, if cases are rarely involved with non-pricing strategies or the significance of services is hard to judge, it would be difficult for lawyers to defend for RPM under the traditional services framework. This paper addresses this problem using a model with one manufacturer and two retailers. The retailers choose their own prices but nothing else. If retailers differ, the model can generate equilibria– only with a uniform wholesale price, the retailers will choose the prices lower than those that would maximize the profit of the supply chain. By imposing minimum RPM, this underpricing problem could be resolved without requiring services to be any significant determinants of the demands faced by retailers. Under certain conditions, the use of RPM could even increase the welfare of both the supply chain and consumer. / 在大部分关于涉及到转售价格维持协议(简称RPM)的法律案件中,我们通常会使用非价格策略(大部分称为“服务”因素)来证明RPM是合法的。非价格策略是Telsor(1960)第一个提出的。然而,如果案件很少涉及非价格策略或者服务的显著性难以衡量,律师在传统的服务因素框架下为RPM辩护会变得很难。本文通过构建一个包含一个厂商和两个零售商的模型来解决这个问题。在模型中,零售商只能选择定产品的价格。如果两个零售商是不相同的,本文模型会得到一个均衡——在只有一个批发价的情况下,零售商选择的售价会低于使得整个供应链获利最多的价格。通过RPM的设置,这个定价过低的问题可以得到解决,而且不需要服务成为零售商需求函数的显著决定因素。在某一些条件下,使用RPM甚至可以增加供应链和消费者的福利。 / Mao, Wenzheng. / Thesis M.Phil. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 36-37). / Abstracts also in Chinese. / Title from PDF title page (viewed on 24, October, 2016). / Detailed summary in vernacular field only.
4

Optimal scheduled maintenance policy based on multiple criteria decision making

Wei, Wen-Kuo,M.S. January 1978 (has links)
Call number: LD2668 .T4 1978 W44 / Master of Science
5

An algebraic model of software evolution

Keller, Benjamin J. 12 March 2009 (has links)
A model of the software evolution process, called the Abstraction Refinement Model, is described which builds on the algebraic influence of the Laws of Programming and the transformational Draco Paradigm. The result is an algebraic structure consisting of the states of the software product (system descriptions) ordered by a relation of relative correctness with transformations defined between the system descriptions. This structure is interpreted as the software evolution space, with the intended semantics given by a model combining axiomatic semantics and the Lindenbaum algebra of a first-order logic. Using this interpretation, software evolution can be represented as a sequence of transformations on system descriptions. The primary contributions of the characterization of software evolution are to the understanding of maintenance and its relationship to development. The influence of development on maintenance is shown as the transfer of a "descriptive context" for the software system. This context is used as an information source during maintenance, and is progressively modified by maintenance activities. These activities are characterized by balanced forward and reverse transformations. The use of reverse transformations explaining the role of reverse engineering in maintenance for information gathering and document reconstruction. Additionally, the form of maintenance affects the performance of the activity, with adaptive maintenance differing from corrective, perfective and preventive maintenance. These factors contribute to the descriptive nature and utility of the Abstraction Refinement Model in defining methodologies for maintenance. / Master of Science
6

Essays in economic theory

Tirole, Jean January 1981 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Economics, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY. / Includes bibliographies. / by Jean Tirole. / Ph.D.
7

Contribution aux approches probabilistes pour le pronostic et la maintenance des systèmes contrôlés / Contribution to probabilistic approaches for prognosis and maintenance of controlled system

Nguyen, Danh Ngoc 24 March 2015 (has links)
Les systèmes de contrôle-commande jouent un rôle important dans le développement de la civilisation et de la technologie moderne. La perte d’efficacité de l’actionneur agissant sur le système est nocive dans le sens où elle modifie le comportement du système par rapport à celui qui est désiré. Cette thèse est une contribution au pronostic de la durée de vie résiduelle (RUL) et à la maintenance des systèmes de contrôle-commande en boucle fermée avec des actionneurs soumis à dégradation. Dans une première contribution, un cadre de modélisation à l'aide d’un processus markovien déterministe par morceaux est considéré pour modéliser le comportement du système. Dans ce cadre, le comportement du système est représenté par des trajectoires déterministes qui sont intersectées par des sauts d'amplitude aléatoire se produisant à des instants aléatoires et modélisant le phénomène de dégradation discret de l'actionneur. La deuxième contribution est une méthode de pronostic de la RUL du système composée de deux étapes : estimation de la loi de probabilité de l'état du système à l'instant de pronostic par le filtre particulaire et calcul de la RUL qui nécessite l'estimation de la fiabilité du système à partir de cet instant. La troisième contribution correspond à la proposition d’une politique de maintenance à structure paramétrique permettant de prendre en compte dynamiquement les informations disponibles conjointement sur l'état et sur l'environnement courant du système et sous la contrainte de dates d'opportunité / The automatic control systems play an important role in the development of civilization and modern technology. The loss of effectiveness of the actuator acting on the system is harmful in the sense that it modifies the behavior of the system compared to that desired. This thesis is a contribution to the prognosis of the remaining useful life (RUL) and the maintenance of closed loop systems with actuators subjected to degradation. In the first contribution, a modeling framework with piecewise deterministic Markov process is considered in order to model the overall behavior of the system. In this context, the behavior of the system is represented by deterministic trajectories that are intersected by random size jumps occurring at random times and modeling the discrete degradation phenomenon of the actuator. The second contribution is a prognosis method of the system RUL which consists of two steps: the estimation of the probability distribution of the system state at the prognostic instant by particle filtering and the computation of the RUL which requires the estimation of the system reliability starting from the prognostic instant. The third contribution is the proposal of a parametric maintenance policy which dynamically take into account the available information on the state and on the current environment of the system and under the constraint of opportunity dates
8

Maintenance of monitored systems with multiple deterioration mechanisms in dynamic environments : application to wind turbines / Modèles de maintenance des systèmes à détériorations multiples en environnement dynamique : application aux éoliennes

Zhu, Wenjin 17 February 2014 (has links)
Les travaux présentés contribuent à la modélisation stochastique de la maintenance de systèmes mono- ou multi-composants à détériorations et à modes de défaillances multiples en environnement dynamique. Dans ce cadre, les contributions portent d'une part sur la modélisation des processus de défaillance, et d'autre part sur la proposition de structures de décision de maintenance intégrant les différents types d'information de surveillance en ligne disponible sur le système (état de détérioration mesuré ou reconstruit, état de l'environnement, ...) et le développement des modèles mathématiques d'évaluation associés. Les modèles de détérioration et de défaillances proposés pour les systèmes mono-composants permettent de rendre compte de sources de détérioration multiples (chocs et détérioration graduelle) et d'intégrer les effets de l'environnement sur la dégradation. Pour les systèmes multi-composants, on insiste sur les risques concurrents, indépendants ou dépendants et sur l'intégration de l'environnement. Les modèles de maintenance développés sont adaptés aux modèles de détérioration proposés et permettent de prendre en compte la contribution de chaque source de détérioration dans la décision de maintenance, ou d'intégrer de l'information de surveillance indirecte dans la décision, ou encore de combiner plusieurs types d'actions de maintenance. Dans chaque cas, on montre comment les modèles développés répondent aux problématiques de la maintenance de turbines et de parcs éoliens / The thesis contributes to stochastic maintenance modeling of single or multi-components deteriorating systems with several failure modes evolving in a dynamic environment. In one hand, the failure process modeling is addressed and in the other hand, the thesis proposes maintenance decision rules taking into account available on-line monitoring information (system state, deterioration level, environmental conditions …) and develops mathematical models to measure the performances of the latter decision rules.In the framework of single component systems, the proposed deterioration and failure models take into account several deterioration causes (chocks and wear) and also the impact of environmental conditions on the deterioration. For multi-components systems, the competing risk models are considered and the dependencies and the impact of the environmental conditions are also studied. The proposed maintenance models are suitable for deterioration models and permit to consider different deterioration causes and to analyze the impact of the monitoring on the performances of the maintenance policies. For each case, the interest and applicability of models are analyzed through the example of wind turbine and wind turbine farm maintenance

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