The goal of the research of this Dissertation is using actuation redundancy to reduce backlash in parallel manipulators (PMs.) Initially, 3-RRR and 3-RPR PM layouts where 3 is the number of branches, R is a revolute joint and P is a prismatic joint, are introduced. Actuated joints will later be underlined in the PM desciptions. A method for determining PM working area for rotated payload platforms, based on a mechanism inversion, is presented. Force solutions for non-redundantly actuated 3-RRR, 3-RRR, 3-RPR and 3-RPR PMs are formulated in terms of screw coordinates. The reciprocal product of screw coordinates is demonstrated to be invarient under changes in reference location and orientation. As examples, the PMs execute basic circle, logarithmic spiral and arc displacement and force trajectories. All non-redundantly-actuated PMs, encounter two backlash-prone zero-actuator-output configurations when executing any of the trajectories. Therefore, non-redundantly actuated PMs are found inadequate for precision applications. Force-uncertainties, where PMs cannot sustain or apply forces in uncertain directions, are examined. For typically actuated 3-RRR and 3-RPR PMs, force uncertainties are identified using screw system arguments based on the existance of 3 actuated forces forming degenerate (rank = 2) planar pencils of forces. These degenerate force pose make arbitrary force and moment application impossible and cause singularities in the force solutions. The working area of the 3-RRR PM is found compatible with all trajectories. This compatibility is due to zero minimum branch length being possible with the limitless angular displacements possible with stacked R joints. In comparison, the 3-RPR PM with minimum joint lengthes imposed on the P joints, has a smaller working area, and is not compatible with any of the trajectories. A P joint modification allowing relative length minimums of zero and a compatible working area identical to the 3-RRR PM, is considered. To address inadequacies, symmetric actuation-redundant 3-RRR and 3-RPR PMs are considered. Pseudo (right Moore-Penrose) inverse of the 3×6 ARS (associated reciprocal screw) matrix is considered to solve for the required actuation. This solution, while providing a minimum 2-norm of the vector of required actuator outputs, does not reduce backlash-prone configurations with all actuators still having two backlash-prone zero-output configurations. An algorithm for reducing backlash, using MATLAB’s constrained optimization routine FMINCON is applied. Minimizing the 2-norm of the vector of actuator outputs, subject to the backlash-free constraint of having outputs ≥ 0 or ≤ 0 depending on the initial values, is considered. Actuators providing the best conditioned ARS matices are utilized for the particular solutions. / Graduate

Structured document retrieval (SDR) systems minimize the effort users spend to locate relevant information by retrieving sub-documents (i.e., parts of, as opposed to entire, documents) to focus the user's attention on the relevant parts of a retrieved document. SDR search tasks are differentiated by the multiplicity of ways that users prefer to spend effort and gain relevant information in SDR. The sub-document retrieval paradigm has required researchers to undertake costly user studies to validate whether new IR measures, based on gain and effort, accurately capture IR performance. We propose the Extended Structural Relevance (ESR) framework as a way, akin to classical set-based measures, to formulate SDR measures that share the common basis of our proposed pillars of SDR evaluation: relevance, navigation and redundancy. Our experimental results show how ESR provides a flexible way to formulate measures, and addresses the challenge of testing measures across related search tasks by replacing costly user studies with low-cost simulation.

国立情報学研究所で電子化したコンテンツを使用している。

Thesis (M.S.)--Ohio University, August, 1998. / Title from PDF t.p.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 33-38). Also available via the Internet.

by Edward Y. Chow, Alan S. Willsky. / "October, 1982." / Bibliography: p. 43-44. / Office of Naval Research Contract No. N00014-77-C-0224 NASA Ames Research Center Grant No. NGL-22-009-124

Two well-known methods of improving the reliability of a system are (i) provision of redundant units, and (ii) repair maintenance. In a redundant system more units made available for performing the system function when fewer are required actually. There are two major types of redundancy - parallel and standby. In this dissertation we are concerned with both these types. Some of the typical assumptions made in the analysis of redundant systems are (i) the repair facility can take up a failed unit for repair at any time, if no other unit is undergoing repair (ii) the system under consideration is needed all the time However, we frequently come accross systems where one or more assumptions have to be relaxed. This is the motivation for the detailed study of the models presented in this dissertation. In this dissertation we present models of redundant systems relaxing one or more of these assumptions simultaneously. More specifically it is a study of stochastic models of redundant systems with 'vacation period' for the repair facility (both standby and parallel systems), and intermittently used systems. The dissertation contains five chapters. Chapter 1 is introductory in nature and contains a brief description of the mathematical techniques used in the analysis of redundant systems. In Chapter 2 assumption (i) is relaxed while studying a model of cold standby redundant system with 'vacation period' for the repair facility. In this model the repair facility is not available for a random time immediately after each repair completion. Integral equations for the reliability and availability functions of the system are derived under suitable assumptions. In Chapter 3, once again assumption (i) is relaxed while studying a model of parallel redundant systems with the same 'vacation period' for the repair facility, explained in the above paragraph. In Chapter 4, the detailed review of intermittently used systems have been studied. In Chapter 5, assumption (ii) is relaxed. This chapter is devoted to the study of an intermittently used 2-unit cold standby system with a single repair facility. This study was carried out using the 'correlated alternating renewal process' and the joint forward recurrence times. All the above models have been studied, when some of the underlying distributions have a non-Markovian nature. They have been analysed using a regeneration point technique. / Mathematical Sciences / M. Sc. (Statistics)

The dissertation discusses problems of redundancy payments and other forms of compensation under labour law. Its focus is to describe in depth the current Czech law system's range of compensation which is related to employment termination. Every termination of employment comes with certain rights as well as obligations for either the employer or the employee. Among some of the obligations, provisions of different types of compensation are found, to which the rights are gained by termination of labour relations that are implied by the law as well as the agreement made by both sides. This dissertation is divided into five chapters. The introduction describes the labour law in general, because labour relations are ones of the most fundamental law relations in the life of almost every person. In the second chapter, we encounter the main topic of this dissertation - redundancy payments issues, what is their purpose, how one's rights to the payment are gained, on what legal grounds, what is the amount paid in specific cases of employment termination, and how it is calculated. The third chapter focuses on a specific clause and qualification agreement on improvement and deepening knowledge, and related labour compensation. Subsequently, in the fourth chapter, I discuss the severance issues as another...

In this Master's thesis there is discussed the subject of redundancy payment and other forms of compensation in labour-law relations. In individual chapters there are described different types of compensation, which the current labour law knows and at the same time there are mentioned even compensations for which employees shall have the right according to the previous legislation. Only marginally there are mentioned compensation provided within the civil service. The Master's thesis is divide into seven chapters. In the first chapter there is performed the systematic classification of compensations, which corresponds with the content of this thesis. Second chapter is focused on the general matters connected with severance payment such as the origin of claim for redundancy payment, difference between contractual and statutory redundancy payment, paying of redundancy payment or return of redundancy payment. There is perform also the comparison with redundancy payment according to the Act No. 65/1965 Coll., Labour Code in effect until 31st December 2006. Third chapter is focused on manners of the termination of labour relation establishing the claim for redundancy payment. In detail there are analysed manners of the termination of labour relation by an employer and termination of labour relation by...

Abstract In industry there is a high demand for algorithms that can efficiently solve search problems. Evolutionary Computing (EC) belonging to a class of heuristics are proven to be well suited to solve search problems, especially optimization tasks. They arrived at that location because of their flexibility, scalability and robustness. However, despite their advantages and increasing popularity, there are numerous opened questions in this research area, many of them related to the design and tuning of the algorithms. A neutral technique called Pseudo Redundancy and related concepts such as Updated Objective Grid (UOG) is proposed to tackle the mentioned problem making an evolutionary approach more suitable for ''real world'' applications while increasing its robustness and efficiency. The proposed UOG technique achieves neutral search by objective function transformation(s) resulting several advantageous features. (a) Simplifies the design of an evolutionary solver by giving population sizing principles and directions to choose the right selection operator. (b) The technique of updated objective grid is adaptive without introducing additional parameters, therefore no parameter tuning required for UOG to adjust it for different environments, introducing robustness. (c) The algorithm of UOG is simple and computationally cheap. (d) It boosts the performance of an evolutionary algorithm on high dimensional (constrained and unconstrained) problems. The theoretical and experimental results from artificial test problems included in this thesis clearly show the potential of the proposed technique. In order to demonstrate the power of the introduced methods under "real" circumstances, the author additionally designed EAs and performed experiments on two industrial optimization tasks. Although, only one project is detailed in this thesis while the other is referred. As the main outcome of this thesis, the author provided an evolutionary method to compute (optimal) daily water pump schedules for the water distribution network of Sopron, Hungary. The algorithm is currently working in industry.