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Untersuchung von Resonanzproblemen am MEYRA E-Rollstuhl 9506 CompactStegemann, Patrick 12 May 2011 (has links)
Der Vortrag zeigt die einzelnen notwendigen Schritte auf, die zur Lösung des Resonanzproblems an der Vorderradaufhängung eines E-Rollstuhls der Firma MEYRA-ORTOPEDIA notwendig waren. Alle Lösungsschritte wurden mit Creo Elements/Pro und seinen Modulen Mechanism Design Option (MDO) und Advanced Mechanica erarbeitet.
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Mathematical contributions for the optimization and regulation of electricity production / Contributions mathématiques pour la régulation et l’optimisation de laproduction d’électricitéHeymann, Benjamin 23 September 2016 (has links)
Nous présentons notre contribution sur la régulation et l’optimisation de la production d’électricité.La première partie concerne l’optimisation de la gestion d’un micro réseau. Nous formulons le programme de gestion comme un problème de commande optimal en temps continu, puis nous résolvons ce problème par programmation dynamique à l’aide d’un solveur développé dans ce but : BocopHJB. Nous montrons que ce type de formulation peut s’étendre à une modélisation stochastique. Nous terminons cette partie par l’algorithme de poids adaptatifs, qui permet une gestion de la batterie du micro réseau intégrant le vieillissement de celle-ci. L’algorithme exploite la structure à deux échelles de temps du problème de commande.La seconde partie concerne des modèles de marchés en réseaux, et en particulier ceux de l’électricité. Nous introduisons un mécanisme d’incitation permettant de diminuer le pouvoir de marché des producteurs d’énergie, au profit du consommateur. Nous étudions quelques propriétés mathématiques des problèmes d’optimisation rencontrés par les agents du marché (producteurs et régulateur). Le dernier chapitre étudie l’existence et l’unicité des équilibres de Nash en stratégies pures d’une classe de jeux Bayésiens à laquelle certains modèles de marchés en réseaux se rattachent. Pour certains cas simples, un algorithme de calcul d’équilibre est proposé.Une annexe rassemble une documentation sur le solveur numérique BocopHJB. / We present our contribution on the optimization and regulation of electricity produc- tion.The first part deals with a microgrid Energy Management System (EMS). We formulate the EMS program as a continuous time optimal control problem and then solve this problem by dynamic programming using BocopHJB, a solver developed for this application. We show that an extension of this formulation to a stochastic setting is possible. The last section of this part introduces the adaptative weights dynamic programming algorithm, an algorithm for optimization problems with different time scales. We use the algorithm to integrate the battery aging in the EMS.The second part is dedicated to network markets, and in particular wholesale electricity markets. We introduce a mechanism to deal with the market power exercised by electricity producers, and thus increase the consumer welfare. Then we study some mathematical properties of the agents’ optimization problems (producers and system operator). In the last chapter, we present some pure Nash equilibrium existence and uniqueness results for a class of Bayesian games to which some networks markets belong. In addition we introduce an algorithm to compute the equilibrium for some specific cases.We provide some additional information on BocopHJB (the numerical solver developed and used in the first part of the thesis) in the appendix.
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Identification of Macro- and Micro-Compliant Mechanism Configurations Resulting in Bistable BehaviorJensen, Brian D. 24 June 2003 (has links) (PDF)
The purpose of this research is to identify the configurations of several mechanism classes which result in bistable behavior. Bistable mechanisms have use in many applications, such as switches, clasps, closures, hinges, and so on. A powerful method for the design of such mechanisms would allow the realization of working designs much more easily than has been possible in the past. A method for the design of bistable mechanisms is especially needed for micro-electro-mechanical systems (MEMS) because fabrication and material constraints often prevent the use of simple, well-known bistable mechanism configurations. In addition, this knowledge allows designers to take advantage of the many benefits of compliant echanisms, especially their ability to store and release energy in their moving segments. Therefore, an analysis of a variety of mechanism classes has been performed to determine the configurations of compliant segments or rigid-body springs in a mechanism which result in bistable behavior. The analysis revealed a relationship between the placement of compliant segments and the stability characteristics of the mechanism which allows either analysis or synthesis of bistable mechanisms to be performed very easily. Using this knowledge, a method of type synthesis for bistable mechanisms has been developed which allows bistable mechanisms to be easily synthesized. Several design examples have been presented which demonstrate the method. The theory has also been applied to the design of several bistable micromechanisms. In the process of searching for usable designs for micro-bistable mechanisms, a mechanism class was defined, known as "Young" mechanisms, which represent a feasible and useful way of achieving micro-mechanism motion similar to that of any four-bar mechanism. Based on this class, several bistable micro-mechanisms were designed and fabricated. Testing demonstrated the ability of the mechanisms to snap between the two stable states. In addition, the mechanisms showed a high degree of repeatability in their stable positions.
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Optimal Consumer-Centric Delay-Efficient Security Management in Multi-Agent Networks: A Game and Mechanism Design Theoretic ApproachSchlake, Farimehr 01 May 2012 (has links)
The main aspiration behind the contributions of this research work is the achievement of simultaneuos delay-efficiency, autonomy, and security through innovative protocol design to address complex real-life problems. To achieve this, we take a holistic approach. We apply theoretical mathematical modeling implementing implications of social-economic behavioral characteristics to propose a cross-layer network security protocol. We further complement this approach by a layer-specific focus with implementations at two lower OSI layers.
For the cross-layer design, we suggest the use of game and mechanism design theories. We design a network-wide consumer-centric and delay-efficient security protocol, DSIC-S. It induces a Dominant Strategy Incentive Compatible equilibrium among all rational and selfish nodes. We prove it is network-wide socially desirable and Pareto optimal. We address resource management and delay-efficiency through synergy of several design aspects. We propose a scenario-based security model with different levels. Furthermore, we design a valuation system to integrate the caused delay in selection of security algorithms at each node without consumer's knowledge of the actual delays. We achieve this by incorporating the consumer's valuation system, in the calculation of the credit transfers through the Vickrey-Clarke-Groves (VCG) payments with Clarke's pivotal rule. As the utmost significant contribution of this work, we solve the revelation theorem's problem of misrepresentation of agents' private information in mechanism design theory through the proposed design. We design an incentive model and incorporate the valuations in the incentives. The simulations validate the theoretical results. They prove the significance of this model and among others show the correlation of the credit transfers to actual delays and security valuations.
In the layer-specific approach for the network-layer, we implement the DSIC-S protocol to extend current IPsec and IKEv2 protocols. IPsec-O and IKEv2-O inherit the strong properties of DSIC-S through the proposed extensions.
Furthermore, we propose yet another layer-specific protocol, the SME_Q, for the datalink layer based on ATM. We develop an extensive simulation software, SMEQSIM, to simulate ATM security negotiations. We simulate the proposed protocol in a comprehensive real-life ATM network and prove the significance of this research work. / Ph. D.
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Duality theory for optimal mechanism designGiannakopoulos, Ioannis January 2015 (has links)
In this work we present a general duality-theory framework for revenue maximization in additive Bayesian auctions involving multiple items and many bidders whose values for the goods follow arbitrary continuous joint distributions over some multi-dimensional real interval. Although the single-item case has been resolved in a very elegant way by the seminal work of Myerson [1981], optimal solutions involving more items still remain elusive. The framework extends linear programming duality and complementarity to constraints with partial derivatives. The dual system reveals the natural geometric nature of the problem and highlights its connection with the theory of bipartite graph matchings. We demonstrate the power of the framework by applying it to various special monopoly settings where a seller of multiple heterogeneous goods faces a buyer with independent item values drawn from various distributions of interest, to design both exact and approximately optimal selling mechanisms. Previous optimal solutions were only known for up to two and three goods, and a very limited range of distributional priors. The duality framework is used not only for proving optimality, but perhaps more importantly, for deriving the optimal mechanisms themselves. Some of our main results include: the proposal of a simple deterministic mechanism, which we call Straight-Jacket Auction (SJA) and is defined in a greedy, recursive way through natural geometric constraints, for many uniformly distributed goods, where exact optimality is proven for up to six items and general optimality is conjectured; a scheme of sufficient conditions for exact optimality for two-good settings and general independent distributions; a technique for upper-bounding the optimal revenue for arbitrarily many goods, with an application to uniform and exponential priors; and the proof that offering deterministically all items in a single full bundle is the optimal way of selling multiple exponentially i.i.d. items.
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Essays in Dynamic ContractingMettral, Thomas 17 April 2019 (has links)
Diese Arbeit enthält drei unabhängige Kapitel, jedes davon im Bereich der Dynamischen Vertragstheorie.
Kapitel I zeigt, dass deterministische dynamische Prinzipal-Agenten-Verträge immer mindestens so ertragreich sind wie stochastische, falls die sogenannte Methode erster Ordnung des dynamischen Mechanismus-Designs erfüllt ist. Meine Ergebnisse legen dar, dass die in der Literatur übliche Einschränkung auf deterministische Verträge zulässig ist, so lange die Methode erster Ordnung gültig ist.
Kapitel II basiert auf einer gemeinsamen Arbeit mit Ilia Krasikov und Rohit Lamba. Ein Großanbieter (Prinzipal) handelt mit einer kleinen Firma (Agent) einen wiederkehrenden Geschäftsvertrag aus, wobei sich der Agent als ungeduldiger erweist. Der optimale Vertrag wird durch zwei Schlüsseleigenschaften beschrieben: Neustart und Abbruch, die vielerlei Eigenschaften der angebotenen Verträge darlegen.
Kapitel III basiert schließlich auf einer gemeinsamen Arbeit mit Rohit Lamba. Darin besitzt der Agent dynamische private Information, die einem Markovprozess folgt. Ein monopolistischer Prinzipal verkauft dem Agenten ein nicht-dauerhaftes Gut und er verpflichtet sich in jeder Periode an den ursprünglich ausgehandelten Vertrag. Die entstehenden Informationskosten verhindern erst-beste Verträge bei auftretender Persistenz im Typ des Agenten.
Diese Arbeit stellt einen Weg bereit, wie man den optimalen deterministischen Vertrag in dynamischen Prinzipal-Agenten-Modellen erhält. Der gewöhnliche Weg mit lediglich lokal nach unten bindenden Anreizverträglichkeitsbedingungen misslingt bei hoher Persistenz der Typrealisierungen und bei stark differenzierender Diskontierung. Zudem zeigt die Arbeit wann mit Gewissheit stochastische Verträge ausgeschlossen werden können. / This dissertation consists of three independent chapters, each in the field of dynamic contracting.
Chapter I shows that deterministic dynamic contracts between a principal and an agent are always at least as profitable to the principal as stochastic ones, if the so-called first-order approach in dynamic mechanism design is satisfied. My results demonstrate that the usual restriction in the literature to deterministic contracts is admissible, as long as the first-order approach is valid.
Chapter II is based on joint work with Ilia Krasikov and Rohit Lamba. We consider a large supplier (principal) who contracts with a small firm (agent) to repeatedly provide working capital in return for payments. The agent is less patient than the principal. The optimal contract is characterized by two key properties: restart and shutdown, which capture various aspects of contracts offered in the marketplace.
Finally, Chapter III is based on joint work with Rohit Lamba. We consider the problem of optimal contracting where the agent has dynamic private information, which follows a Markov process. In each period, a monopolistic principal sells a nondurable good to the agent and she commits to the contract she made in the initial period. The emerging information costs prevent first-best contracts whenever there is persistency in the agent’s type.
This thesis provides a strategy on how to obtain the optimal deterministic contract in dynamic principal-agent models with Markovian type realizations. We see that the usual approach with only local downward binding incentive compatibility constraints does not work for highly persistent type realizations and for large differences in discounting. Furthermore, I show in which situations we with certainty can exclude stochastic contracts.
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From Personal to Impersonal Exchange in Ideas : Experimental Study of Trade in Organized Markets for PatentsUllberg, Eskil January 2009 (has links)
The patent system has developed over a period of over 500 years. The initial motivation was a desire to import privately held technology to advance economic development, offering excluding and transferrable rights through licensing to “inventors” for the disclosure and perfection of their “contrivance” (invention). These rights have gradually developed to internationally accepted private property rights on technology and are today in many wayssimilar to physical assets, establishing, since 1883, the basis for an international system for trade in technology in its own rights. The thesis is a dual study of contract and mechanism design for experimental trading with patents. Experimental economics is used as a method to gather data on behavior, varying environmental and institutional parameters. An informal price theory is developed and tested. The experimental research adds to the static analysis literature by using a dynamic analysis in a behaviorally rich experimental system of specialized agents and competitive demand-side bidding on a linear contract, the “patent product.” The microeconomic system has primary and secondary markets, traders, and a linear contract on patents with limitedvalidity and uncertain values. The main results show that risks are shifted away from invention to innovation through demand-side bidding, including traders, creating incentives for increased technologycompetition and economic growth. When a linear contract – fixed fee plus royalty – is used totrade the patents, the fixed fee approaches the blocking value of the patent, in support of theproposed price theory (blocking formally similar to insurance). Such shift in risk bearing maybe beneficial for developing nations in leveraging their human capital through education andincreasing global market access through the patent system. The competitive bidding increasesthe dynamic market efficiency considerably, clearly indicating the dynamic value of the patentsystem. Market efficiency is however still low compared to other typical auction markets,suggesting further experiments to increase efficiency before it will be possible to provide helpful advice about what to do in the field. Dynamic gains increase with increased demandsidebidding and high patent validity. Tentative policy proposals are made for patent,development and innovation policy. The experiments have been carried out at the Interdisciplinary Center for Economic Science, George Mason University, USA. / QC 20100813
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Essays on contracts and social preferencesZubrickas, Robertas January 2009 (has links)
This thesis deals with the problems of optimal grading, employee performance evaluation by unaccountable managers, and the evolution of inequity-averse preferences. The purpose is to explain certain stylized facts related to these problems, and this is attempted with the help of contract-theoretic models. Chapter 1 of this thesis studies a teacher-student relationship as a principal-agent model with a costless reward structure. The model shows that the stylized fact of a mismatch and low correlation between students' abilities and their grades can be the expected-effort-maximizing outcome of teachers' optimal grading. Chapter 2 presents a three-tier model of a firm's economic organization, which is centered on the observation that managers do not fully internalize the payroll expenses they incur. With the idea that the degree of manager accountability varies inversely with firm size, the model predicts that the compression of ratings, the large-firm wage premium, and the inverse relationship between wage dispersion and firm size can actually be equilibrium outcomes. The last chapter presents an evolutionary argument for the endogeneity of people's preferences with respect to market exposure. It shows that aversion to income inequality observed empirically could have evolved as an optimal response to merchants' price discrimination. / <p>Diss. Stockholm : Handelshögskolan, 2009</p>
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Outils numériques pour la conception de mécanismes / Numerical tools for mechanism designHentz, Gauthier 18 September 2017 (has links)
Dans le contexte médico-chirurgical, la robotique peut être d’un grand intérêt pour des procédures plus sûres et plus précises. Les contraintes d’encombrement sont cependant très fortes et des mobilités complexes peuvent être nécessaires. A ce jour, la conception de mécanismes non conventionnels dédiés est alors difficile à réaliser faute d’outils génériques permettant une évaluation rapide de leurs performances. Cette thèse associe la continuation de haut-degré et la différentiation automatique pour répondre à cette problématique en introduisant une méthode de modélisation et un formalisme génériques pour la conception de mécanismes. Nos contributions concernent en particulier le développement d’outils numériques pour l’évaluation de l’espace de travail, et de la localisation et la nature des singularités d’un mécanisme, et une analyse de sensibilité de haut-degré. Ceux-ci sont évalués sur des mécanismes de référence. / In the medical and surgical background, robotics can be of great interest for safer and more accurate procedures. Size constraints are however strong and complex movements may be necessary. To date, the design of dedicated non-conventional mechanisms is then a difficult task because of a lack of generic tools allowing a fast evaluation of their performances. This thesis combines higher-order continuation and automatic differentiation to adress this issue through the introduction of a generic modelling method and a generic formalism for mechanism design. Our contributions especially concern the development of numerical tools for the evaluation of the workspace, of the singularity localization and nature, and for a higher-order sensitivity analysis. These tools are evaluated on reference mechanisms.
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Essais sur la liquidité, la banque centrale et ses actions en dernier ressort / Essays on liquidity, the central bank and its actions of last resortRieu-Foucault, Anne-Marie 22 November 2017 (has links)
Cette thèse comprend trois essais sur le futur des banques centrales et sur la manière dont elles doivent réguler la liquidité. Réguler la liquidité pour le futur, nécessite pour les banques centrales, de justifier et de concevoir une politique de la liquidité. Cette politique de la liquidité existe de fait sous la forme des mesures non conventionnelles mais n’est pas formalisée. L’apport de cette thèse est de proposer une conceptualisation de la politique de la liquidité, comme élément marquant du futur des banques centrales et comme fondation théorique des rôles en dernier ressort des banques centrales. La thèse montrera qu’il s’agit en fait d’une politique des liquidités du fait de l’existence de différents types de liquidités. Elle l’illustrera par la proposition d’un modèle théorique et mettra en relation théorie et pratique des liquidités. La thèse traite le rôle de la banque centrale sur la liquidité tout d’abord sous la forme d’un preneur de risque en dernier ressort puis ensuite sous la forme d’un agent central agissant sur les différentes formes de liquidité. Les deux premiers essais couvrent la problématique de la banque centrale, preneur de risque en dernier ressort, sous un aspect positif dans le premier essai puis sous un aspect normatif dans le deuxième. Le dernier essai intègre le concept de preneur de risque en dernier ressort dans un ensemble plus large d’actions de la banque centrale, couvrant les différentes formes de liquidité. / This PhD thesis includes three essays on the future of central banks and how they should regulate liquidity. Regulating liquidity for the future, requires for central banks to justify and design a liquidity policy. This policy of liquidity actually exists in the form of unconventional measures but is not formalized. The contribution of this thesis is to propose a conceptualization of a liquidity policy as a key element for the future of central banks and as a theoretical foundation for the roles of central banks as last resorts. The thesis will show that it is actually a policy of liquidities because of the existence of different types of liquidity. It will illustrate it by proposing a theoretical model and by linking theory and practice of liquidity. The thesis deals with the role of the central bank on liquidity, first in the form of a risk taker of last resort and then in the form of a central agent acting on the various forms of liquidities. The first two essays cover the problem of the central bank as risk taker of last resort, under a positive aspect in the first essay and then under a normative aspect in the second. The last essay incorporates the concept of risk taker of last resort into a broader set of central bank actions covering different forms of liquidities.
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