• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1091
  • 239
  • 152
  • 123
  • 76
  • 51
  • 35
  • 24
  • 24
  • 23
  • 18
  • 16
  • 8
  • 7
  • 7
  • Tagged with
  • 2218
  • 322
  • 217
  • 175
  • 171
  • 169
  • 169
  • 163
  • 130
  • 128
  • 120
  • 118
  • 115
  • 112
  • 108
  • 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.
161

Betting on the Unexpected: The Effect of Expectation Matching on Choice Strategies in a Binary Choice Task

James, Greta January 2012 (has links)
Probability matching is the tendency to predict outcomes in accordance with their actual contingencies in a binary choice task. It is, however, a suboptimal response if the aim is to maximize correct predictions. I review two theories that attempt to explain why probability matching occurs: the pattern-search hypothesis and dual-systems theory. These theories are tested in two studies which suggest that dual-systems theory provides a better account of probability matching behavior. Studies 3, 4, and 5 then provide evidence for an extension of the dual-systems theory, called expectation matching, which is intended to explain why probability matching is the intuitive response to a binary choice problem.
162

Production Optimization Of A Gas Condensate Reservoir Using A Black Oil Simulator And Nodal System Analysis:a Case Study

Mindek, Cem 01 June 2005 (has links) (PDF)
In a natural gas field, determining the life of the field and deciding the best production technique, meeting the economical considerations is the most important criterion. In this study, a field in Thrace Basin was chosen. Available reservoir data was compiled to figure out the characteristics of the field. The data, then, formatted to be used in the commercial simulator, IMEX, a subprogram of CMG (Computer Modeling Group). The data derived from the reservoir data, used to perform a history match between the field production data and the results of the simulator for a 3 year period between May 2002 and January 2005. After obtaining satisfactory history matching, it was used as a base for future scenarios. Four new scenarios were designed and run to predict future production of the field. Two new wells were defined for the scenarios after determining the best region in history matching. Scenario 1 continues production with existing wells, Scenario 2 includes a new well called W6, Scenario 3 includes another new well, W7 and Scenario 4 includes both new defined wells, W6 and W7. All the scenarios were allowed to continue until 2010 unless the wellhead pressure drops to 500 psi. None of the existing wells reached 2010 but newly defined wells achieved to be on production in 2010. After comparing all scenarios, Scenario 4, production with two new defined wells, W6 and W7, was found to give best performance until 2010. During the scenario 4, between January 2005 and January 2010, 7,632 MMscf gas was produced. The total gas production is 372 MMscf more than Scenario 2, the second best scenario which has a total production of 7,311MMscf. Scenario 3 had 7,260 MMscf and Scenario 1 had 6,821 MMscf respectively. A nodal system analysis is performed in order to see whether the initial flow rates of the wells are close to the optimum flow rates of the wells, Well 1 is found to have 6.9 MMscf/d optimum production rate. W2 has 3.2 MMscf/d, W3 has 8.3 MMscf/d, W4 has 4.8 MMscf/d and W5 has 0.95 MMscf/d optimum production rates respectively.
163

Acuity of force appreciation in the osteoarthritic knee joint

Brereton, Helen P Unknown Date (has links)
Osteoarthritis and ageing have been shown to induce changes in the number and health of peripheral mechanoreceptors. Whilst position and movement awareness in the osteoarthritic knee have been studied extensively, little work to date has been produced on muscle force awareness in this subject group. Poor force acuity may contribute to muscle and joint pain and dysfunction, and additionally hinder rehabilitation efforts in an osteoarthritic population. Overestimation of the muscles forces required for a given task, resulting in greater joint compression forces, may aggravate and inflame osteoarthritic symptoms. Underestimation of required muscle forces may amplify existing joint instability, increasing the risk of injury in an osteoarthritic population. Additionally, both under and overloading of muscles during the rehabilitation process can delay the return to full function after injury.When regarding the neurological process of force coding, current debate centres on the relative importance of centrally generated motor command mediated 'sense of effort' versus the peripheral mechanoreceptor signalled 'sense of tension' as the dominant coding process, with central mechanisms favoured in the majority of studies published to date. The purpose of this study was to investigate muscle force awareness in the knee extensors and flexors and hands of subjects with and without knee joint osteoarthritis. Twenty one subjects with knee joint osteoarthritis and 23 age and gender matched subjects with no known knee pathology were evaluated. All subjects performed ipsilateral isometric force estimation and force matching tasks, at levels scaled to individual maximum voluntary capacity (MVC). Errors in estimation and matching acuity were normalised to reference targets (comparison force/reference force) giving a relative score (RS) to allow comparison across submaximal force levels with RS less than 1.0 indicating that subjects produced insufficient force and vice versa.Maximal voluntary capacity tests revealed significantly lower (p<0.05) peak knee extension torque (111.2 Nm versus 145.3 Nm), but similar peak knee flexion torque (46.1 Nm versus 45.4 Nm for osteoarthritis and control subjects respectively). A pattern of overestimation at low reference levels and underestimation at high reference levels was demonstrated by all subjects. In the lower limb, force appreciation differed significantly between muscle groups regardless of knee condition, with knee extensors demonstrating greater overall accuracy than knee flexors. There was a significant difference (p<0.05) in force estimation ability and a trend to significance (p=0.066) for force matching acuity across groups at the 10% MVC test level. A significant (p<0.05) group difference in grip force estimation ability between the lowest and highest target levels was demonstrated.It can be concluded that there are small differences in force acuity in osteoarthritis subjects at lower submaximal force targets when compared to healthy age matched peers. The notion of information redundancy, whereby no new proprioceptive inputs, regardless of origin, are able to effect an improvement in force acuity in a given situation has been demonstrated in previous studies that reported relatively stable force matching acuity at forces between 30% and 60% of maximal capacity. The poor comparative force perception demonstrated in this study by the osteoarthritis group at the lower submaximal test levels supports the notion that centrally generated copies of motor commands do not provide sufficient data to adequately encode force magnitude at low levels of force generation, evoking a greater reliance data received from peripheral mechanoreceptors. This has significant implications for this subject group given that the majority of daily tasks require only low levels of force generation. Given that perceptive acuity in a variety of sensory modalities has been shown to improve with training there may be a role for force perception training in older adults with osteoarthritis.
164

3D surface matching from range images using multiscale local features.

Ho, Huy Tho January 2009 (has links)
Object recognition is one of the most important problems in computer vision. Traditional object recognition techniques are usually performed on optical images that are 2D projections of the 3D world. Information about the depth of objects in the scene is not provided explicitly in these images and thus, it makes 2D object recognition techniques sensitive to changes in illumination and shadowing. As surface acquisition methods such as LADAR or range scanners are becoming more popular, there is an increasing interest in the use of three-dimensional geometric data in object recognition to overcome these limitations. However, the matching of 3D free-form surfaces is also a difficult problem due to the shape and topological complexity of 3D surfaces. In addition, the problem is further complicated by other issues such as variations in surface sampling resolution, occlusion, clutter and sensor noise. The huge amount of information required to describe a 3D surface is also another challenge that 3D surface matching techniques have to deal with. This thesis investigates the problems of 3D surface matching that include 3D surface registration and object recognition from range images. It focuses on developing a novel and efficient framework for aligning 3D surfaces in different coordinate systems and from this, recognizing 3D models from scenes with high levels of occlusion and clutter using multi-scale local features. The first part of the thesis presents two different schemes for extracting salient geometric features from 3D surfaces using surface curvature measures known as the curvedness and shape index. By deriving the scale-space representation of the input surface, surface positions with high local curvature or high local shape variations are selected as features at various degrees of scale. One advantage of the proposed approaches is their applicability to both 3D meshes with connectivity information and unstructured point clouds. In the second part of the thesis, an application of the multi-scale feature extraction framework to 3D surface registration and object recognition is proposed. A Delaunay tetrahedrization is performed on the features extracted from each input range image to obtain a set of triangles. Possible correspondences are found by matching all possible pairs of triangles between the scene and model surfaces. From these correspondences, possible transformations between the two surfaces can be hypothesized and tested. In order to increase the accuracy and efficiency of the algorithm, various surface geometric and rigidity constraints are applied to prune unlikely correspondences. By finding the match that aligns the largest number of features between the two surfaces, the best transformation can be estimated. In the case of surface registration, this transformation can be used to coarse-align two different views of the same object. In the case of 3D object recognition, it provides information about the possible pose (location and orientation) of the model in the scene surface. Experimental results on a variety of 3D models and real scenes are shown to verify the effectiveness and robustness of the approach. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474505 / Thesis (M.App.Sc.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2009
165

A Unified Approach to Adapting and Retrieving Formally Specified Components for Reuse

Hemer, David George Unknown Date (has links)
This thesis presents an approach to reusing components which alleviates some of the main problems encountered in component-based reuse; in particular modifying components to suit user's specific needs, and locating suitable components within a library. The focus of the thesis is on components described using a formal language (in other words components with a formal interface specification). The main reason for this is the concise and precise nature of formal languages, which can be exploited in developing more sophisticated methods and tools which take advantage of the semantics of the component. The solution is presented in two main stages: firstly a framework for adapting components is defined; secondly a framework for retrieving components based on matching component interfaces is defined. Both of these frameworks take advantage of the formal nature of the component interfaces, as a result more sophisticated tools can be developed. For generality it is proposed that formal languages used to represent interfaces are partitioned into three separate levels of granularity - expressions, units and modules - and solutions to adaptation and retrieval are developed separately at each level. An important consideration in developing these frameworks is to ensure that certain component properties are preserved when adapting and retrieving components. Having proposed these general frameworks, algorithms for adapting and retrieving components are defined in a more concrete and detailed sense within the CARE system. CARE was chosen because the language is relatively simple and compact, yet contains many of the features found in other formal languages, including: variables; functions; predicates; binders; application; typing; parameters; inputs and outputs (and their types); preconditions and postconditions; textual and formal parameters; separation of specification and implementation; case statements; modules; applicability conditions; encapsulation; and information hiding. These techniques for adapting and retrieving components have been prototyped as extensions to existing CARE tools. As a means of illustrating the value that these extensions have added to the overall CARE system, several example developments using the extended tools are presented at the end of the thesis. The approach to component reuse presented in this thesis represents a significant advance on other similar approaches. The approach given here is far more general than other approaches, particularly with respect to the scope of components and their interfaces that are considered. Also the adaptation framework goes beyond other approaches which have typically been restricted to parameter instantiation.
166

On the likely number of stable marriages

Lennon, Craig, January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 123-124).
167

On the likely number of stable marriages /

Lennon, Craig, January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Includes vita and abstract. Includes bibliographical references (leaves 123-124). Also available online via OhioLINK's ETD Center http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1194991095
168

Three Essays in Economics

January 2011 (has links)
abstract: This dissertation presents three essays in economics. Firstly, I study the problem of allocating an indivisible good between two agents under incomplete information. I provide a characterization of mechanisms that maximize the sum of the expected utilities of the agents among all feasible strategy-proof mechanisms: Any optimal mechanism must be a convex combination of two fixed price mechanisms and two option mechanisms. Secondly, I study the problem of allocating a non-excludable public good between two agents under incomplete information. An equal-cost sharing mechanism which maximizes the sum of the expected utilities of the agents among all feasible strategy-proof mechanisms is proved to be optimal. Under the equal-cost sharing mechanism, when the built cost is low, the public good is provided whenever one of the agents is willing to fund it at half cost; when the cost is high, the public good is provided only if both agents are willing to fund it. Thirdly, I analyze the problem of matching two heterogeneous populations. If the payoff from a match exhibits complementarities, it is well known that absent any friction positive assortative matching is optimal. Coarse matching refers to a situation in which the populations into a finite number of classes, then randomly matched within these classes. The focus of this essay is the performance of coarse matching schemes with a finite number of classes. The main results of this essay are the following ones. First, assuming a multiplicative match payoff function, I derive a lower bound on the performance of n-class coarse matching under mild conditions on the distributions of agents' characteristics. Second, I prove that this result generalizes to a large class of match payoff functions. Third, I show that these results are applicable to a broad class of applications, including a monopoly pricing problem with incomplete information, as well as to a cost-sharing problem with incomplete information. In these problems, standard models predict that optimal contracts sort types completely. The third result implies that a monopolist can capture a large fraction of the second-best profits by offering pooling contracts with a small number of qualities. / Dissertation/Thesis / Ph.D. Economics 2011
169

Alocação de estudantes aos centros de pós-graduação em economia no Brasil: um experimento natural em organização de mercado / On the allocation of students to postgraduate programs in economics in Brazil: a natural experiment in market organization

Felipe Palmeira Bardella 29 November 2005 (has links)
Apresentamos a teoria sobre mercados de dois lados, centralizados e descentralizados, para analisar o mercado de admissão de estudantes aos Centros de Pós-graduação em Economia no Brasil ao longo dos últimos 15 anos. Iniciamos descrevendo a história da organização deste mercado até a época atual. As falhas do sistema descentralizado e as hipóteses sobre o insucesso do procedimento centralizado de 1997 são discutidas. Observações empíricas são utilizadas para propor um modelo teórico que represente aproximadamente o atual mecanismo descentralizado e explique a aparente duradoura aplicação desse mecanismo. Por fim, tecemos considerações a respeito das possibilidades de aprimoramento deste mercado com modificações do mecanismo existente. / We present the theory of two-sided matching markets, with centralized and decentralized mechanisms, in order to analyze a Brazilian market in which graduated students seek positions in postgraduate programs in economics. We first describe the institutional history of this market. The failures of the decentralized procedure and the hypothesis about the failure of the 1997 centralized mechanism are discussed. Empirical observations are used to propose a theoretical model that represents the actual decentralized matching procedure of the market. Based in this model we explain the apparent long-lasting use of this decentralized mechanism. Finally, we make considerations about the possibilities of developments in this market by modifying the mechanism used today.
170

Problemas de emparelhamentos estáveis / Stable matching problems

Sambinelli, Maycon, 1988- 25 August 2018 (has links)
Orientador: Orlando Lee / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-25T09:16:09Z (GMT). No. of bitstreams: 1 Sambinelli_Maycon_M.pdf: 1793287 bytes, checksum: 11aee090fa90d75328e5caf25578f7da (MD5) Previous issue date: 2014 / Resumo: Problemas de emparelhamentos estáveis consistem em dividir um ou mais grupos de agentes em pares, onde cada agente possui uma lista de preferências ordenada, e deseja-se encontrar uma emparelhamento entre eles que respeite um critério de estabilidade que é baseado nas suas preferências. Estes problemas são importantes pois possuem muitas aplicações práticas, tais como associação de residentes de medicina à hospitais, alocação de recursos em comunicação sem fio e doação de rins. Devido à importância do tema, esta dissertação apresenta um survey descrevendo os problemas mais importantes junto com seus principais resultados / Abstract: Stable matching problems consist of dividing one or more groups of agents in pairs, where each agent has an ordered preference list, and one wish to find a matching between them which respects a stability criterion that is based on their preferences. These problems are important because they have many practical applications, such as association of medical residents to hospitals, resource allocation in wireless communication and kidney donation. Due to the importance of the topic, this dissertation presents a survey describing the most important problems along with its main results / Mestrado / Ciência da Computação / Mestre em Ciência da Computação

Page generated in 0.3153 seconds