979 resultados para Constraint Satisfaction Problem


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L’objectif de ce mémoire est d’étudier l’impact différencié de la satisfaction envers les bonis individuels et les bonis collectifs sur l’intention de rester (au sein d’une entreprise donnée) des travailleurs du secteur des technologies de l’information et des communications. Afin d’étudier cette question, trois hypothèses de recherche ont été émises à l’aide des théories suivantes : 1- la théorie de l’agence, 2- la théorie des attentes et 3- la théorie de l’échange social de Blau (1964). Selon la première hypothèse, la satisfaction envers les bonis individuels contribue à accroître l’intention de rester des travailleurs du secteur des TIC. La seconde hypothèse avance que la satisfaction envers les bonis collectifs contribue à accroître l’intention de rester des travailleurs du secteur des TIC. Enfin, la dernière hypothèse soutient que la satisfaction envers les bonis individuels a un impact plus important sur l’intention de rester des travailleurs du secteur des TIC que la satisfaction envers les bonis collectifs. Les données utilisées pour valider nos hypothèses ont été recueillies dans le cadre d'une enquête portant sur « les relations entre la rémunération, la formation et le développement des compétences avec l’attraction et la rétention des employés clés ». Ces données de nature longitudinale, proviennent d'une entreprise canadienne du secteur des TIC. La population étudiée regroupe les nouveaux employés embauchés entre le 1er avril 2009 et le 30 septembre 2010. Nos résultats confirment l’Hypothèse 1 voulant que la satisfaction envers les bonis individuels contribue à accroître l’intention de rester des travailleurs du secteur des TIC. À l’inverse, ces résultats infirment l’Hypothèse 2. La satisfaction envers les bonis collectifs n’a donc pas d’impact significatif sur l’intention de rester. Malgré un problème de colinéarité, nos résultats suggèrent de confirmer l’Hypothèse 3 voulant que la satisfaction envers les bonis individuels ait un impact plus important sur l’intention de rester des travailleurs du secteur des TIC que la satisfaction envers les bonis collectifs. Les résultats indiquent également que le niveau de scolarité et l’engagement organisationnel ont un impact positif sur l’intention de rester des travailleurs. Les analyses longitudinales révèlent que les différences entre les caractéristiques des travailleurs expliquent davantage l’intention de rester, que les différences à travers les temps chez un même travailleur.

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Female genital pain is a prevalent condition that can disrupt the psychosexual and relational well-being of affected women and their romantic partners. Despite the intimate context in which the pain can be elicited (i.e., during sexual intercourse), interpersonal correlates of genital pain and sexuality have not been widely studied in comparison to other psychosocial factors. This review describes several prevailing theoretical models explaining the role of the partner in female genital pain: the operant learning model, cognitive-behavioral and communal coping models, and intimacy models. The review includes a discussion of empirical research on the interpersonal and partner correlates of female genital pain and the impact of genital pain on partners’ psychosexual adjustment. Together, this research highlights a potential reciprocal interaction between both partners’ experiences of female genital pain. The direction of future theoretical, methodological, and clinical research is discussed with regard to the potential to enhance understanding of the highly interpersonal context of female genital pain

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The underlying assumptions for interpreting the meaning of data often change over time, which further complicates the problem of semantic heterogeneities among autonomous data sources. As an extension to the COntext INterchange (COIN) framework, this paper introduces the notion of temporal context as a formalization of the problem. We represent temporal context as a multi-valued method in F-Logic; however, only one value is valid at any point in time, the determination of which is constrained by temporal relations. This representation is then mapped to an abductive constraint logic programming framework with temporal relations being treated as constraints. A mediation engine that implements the framework automatically detects and reconciles semantic differences at different times. We articulate that this extended COIN framework is suitable for reasoning on the Semantic Web.

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The underlying assumptions for interpreting the meaning of data often change over time, which further complicates the problem of semantic heterogeneities among autonomous data sources. As an extension to the COntext INterchange (COIN) framework, this paper introduces the notion of temporal context as a formalization of the problem. We represent temporal context as a multi-valued method in F-Logic; however, only one value is valid at any point in time, the determination of which is constrained by temporal relations. This representation is then mapped to an abductive constraint logic programming framework with temporal relations being treated as constraints. A mediation engine that implements the framework automatically detects and reconciles semantic differences at different times. We articulate that this extended COIN framework is suitable for reasoning on the Semantic Web.

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The underlying assumptions for interpreting the meaning of data often change over time, which further complicates the problem of semantic heterogeneities among autonomous data sources. As an extension to the COntext INterchange (COIN) framework, this paper introduces the notion of temporal context as a formalization of the problem. We represent temporal context as a multi-valued method in F-Logic; however, only one value is valid at any point in time, the determination of which is constrained by temporal relations. This representation is then mapped to an abductive constraint logic programming framework with temporal relations being treated as constraints. A mediation engine that implements the framework automatically detects and reconciles semantic differences at different times. We articulate that this extended COIN framework is suitable for reasoning on the Semantic Web.

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The underlying assumptions for interpreting the meaning of data often change over time, which further complicates the problem of semantic heterogeneities among autonomous data sources. As an extension to the COntext INterchange (COIN) framework, this paper introduces the notion of temporal context as a formalization of the problem. We represent temporal context as a multi-valued method in F-Logic; however, only one value is valid at any point in time, the determination of which is constrained by temporal relations. This representation is then mapped to an abductive constraint logic programming framework with temporal relations being treated as constraints. A mediation engine that implements the framework automatically detects and reconciles semantic differences at different times. We articulate that this extended COIN framework is suitable for reasoning on the Semantic Web.

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The estimation of camera egomotion is a well established problem in computer vision. Many approaches have been proposed based on both the discrete and the differential epipolar constraint. The discrete case is mainly used in self-calibrated stereoscopic systems, whereas the differential case deals with a unique moving camera. The article surveys several methods for mobile robot egomotion estimation covering more than 0.5 million samples using synthetic data. Results from real data are also given

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Les restriccions reals quantificades (QRC) formen un formalisme matemàtic utilitzat per modelar un gran nombre de problemes físics dins els quals intervenen sistemes d'equacions no-lineals sobre variables reals, algunes de les quals podent ésser quantificades. Els QRCs apareixen en nombrosos contextos, com l'Enginyeria de Control o la Biologia. La resolució de QRCs és un domini de recerca molt actiu dins el qual es proposen dos enfocaments diferents: l'eliminació simbòlica de quantificadors i els mètodes aproximatius. Tot i això, la resolució de problemes de grans dimensions i del cas general, resten encara problemes oberts. Aquesta tesi proposa una nova metodologia aproximativa basada en l'Anàlisi Intervalar Modal, una teoria matemàtica que permet resoldre problemes en els quals intervenen quantificadors lògics sobre variables reals. Finalment, dues aplicacions a l'Enginyeria de Control són presentades. La primera fa referència al problema de detecció de fallades i la segona consisteix en un controlador per a un vaixell a vela.

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The purpose of this paper is to investigate several analytical methods of solving first passage (FP) problem for the Rouse model, a simplest model of a polymer chain. We show that this problem has to be treated as a multi-dimensional Kramers' problem, which presents rich and unexpected behavior. We first perform direct and forward-flux sampling (FFS) simulations, and measure the mean first-passage time $\tau(z)$ for the free end to reach a certain distance $z$ away from the origin. The results show that the mean FP time is getting faster if the Rouse chain is represented by more beads. Two scaling regimes of $\tau(z)$ are observed, with transition between them varying as a function of chain length. We use these simulations results to test two theoretical approaches. One is a well known asymptotic theory valid in the limit of zero temperature. We show that this limit corresponds to fully extended chain when each chain segment is stretched, which is not particularly realistic. A new theory based on the well known Freidlin-Wentzell theory is proposed, where dynamics is projected onto the minimal action path. The new theory predicts both scaling regimes correctly, but fails to get the correct numerical prefactor in the first regime. Combining our theory with the FFS simulations lead us to a simple analytical expression valid for all extensions and chain lengths. One of the applications of polymer FP problem occurs in the context of branched polymer rheology. In this paper, we consider the arm-retraction mechanism in the tube model, which maps exactly on the model we have solved. The results are compared to the Milner-McLeish theory without constraint release, which is found to overestimate FP time by a factor of 10 or more.

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The Team Formation problem (TFP) has become a well-known problem in the OR literature over the last few years. In this problem, the allocation of multiple individuals that match a required set of skills as a group must be chosen to maximise one or several social positive attributes. Speci�cally, the aim of the current research is two-fold. First, two new dimensions of the TFP are added by considering multiple projects and fractions of people's dedication. This new problem is named the Multiple Team Formation Problem (MTFP). Second, an optimization model consisting in a quadratic objective function, linear constraints and integer variables is proposed for the problem. The optimization model is solved by three algorithms: a Constraint Programming approach provided by a commercial solver, a Local Search heuristic and a Variable Neighbourhood Search metaheuristic. These three algorithms constitute the first attempt to solve the MTFP, being a variable neighbourhood local search metaheuristic the most effi�cient in almost all cases. Applications of this problem commonly appear in real-life situations, particularly with the current and ongoing development of social network analysis. Therefore, this work opens multiple paths for future research.

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I dagens samhälle är det allt viktigare för företag att behålla sina existerande kunder då konkurrensen blir allt hårdare. Detta medför att företag försöker vidta åtgärder för att vårda relationer med sina kunder. Detta problem är även högst relevant inom IT-branschen. Inom IT-branschen är det vanligt att arbeta agilt i IT-projekt. Vår samarbetspartner har sett ett ökat behov av att mäta servicekvalitet på ett återkommande sätt inom IT-projekt, detta för att mäta relevanta variabler som sträcker sig utanför kravspecifikationen. För att mäta framgång gällande detta arbetssätt vill man kunna mäta Nöjd Kund Index (NKI) för att kunna jämföra IT-projekt internt i företaget. Då tidigare forskning visat avsaknad av modeller innehållande både mätning av servicekvalitet samt NKI har lämplig litteratur studerats där det framkommit att modellen SERVQUAL är vedertagen för mätning av servicekvalitet och modellen American Customer Satisfaction Index (ACSI) är vedertagen för mätning av NKI. Detta har legat till grund för arbetets problemformulering och syfte. Syftet med arbetet är att skapa en vidareutvecklad modell för mätning av NKI för att jämföra IT-projekt internt samt återkommande mätning av servicekvalitet inom IT-projekt. Framtagande av denna modell har sedan skett genom forskningsstrategin Design and Creation. Intervjuer har genomförts för kravfångst till den vidareutvecklade modellen. Resultatet av denna forskningsstrategi blev sedan en vidareutvecklad modell baserad på ovan nämnda modeller med återkommande förhållningssätt för mätning av servicekvalitet inom IT-projekt och mätning av NKI för att jämföra IT-projekt internt i företaget. Den framtagna modellen har sedan verifierats genom ytterligare intervjuer med respondenter som innehar god erfarenhet från kundsidan av IT-projekt. Från dessa intervjuer kunde sedan slutsats dras att denna modell är att anse som applicerbar i empirin gällande IT-projekt.

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This paper proposes a new approach and coding scheme for solving economic dispatch problems (ED) in power systems through an effortless hybrid method (EHM). This novel coding scheme can effectively prevent futile searching and also prevents obtaining infeasible solutions through the application of stochastic search methods, consequently dramatically improves search efficiency and solution quality. The dominant constraint of an economic dispatch problem is power balance. The operational constraints, such as generation limitations, ramp rate limits, prohibited operating zones (POZ), network loss are considered for practical operation. Firstly, in the EHM procedure, the output of generator is obtained with a lambda iteration method and without considering POZ and later in a genetic based algorithm this constraint is satisfied. To demonstrate its efficiency, feasibility and fastness, the EHM algorithm was applied to solve constrained ED problems of power systems with 6 and 15 units. The simulation results obtained from the EHM were compared to those achieved from previous literature in terms of solution quality and computational efficiency. Results reveal that the superiority of this method in both aspects of financial and CPU time. (C) 2011 Elsevier Ltd. All rights reserved.

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The transmission network planning problem is a non-linear integer mixed programming problem (NLIMP). Most of the algorithms used to solve this problem use a linear programming subroutine (LP) to solve LP problems resulting from planning algorithms. Sometimes the resolution of these LPs represents a major computational effort. The particularity of these LPs in the optimal solution is that only some inequality constraints are binding. This task transforms the LP into an equivalent problem with only one equality constraint (the power flow equation) and many inequality constraints, and uses a dual simplex algorithm and a relaxation strategy to solve the LPs. The optimisation process is started with only one equality constraint and, in each step, the most unfeasible constraint is added. The logic used is similar to a proposal for electric systems operation planning. The results show a higher performance of the algorithm when compared to primal simplex methods.

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In this paper, the concept of Matching Parallelepiped (MP) is presented. It is shown that the volume of the MP can be used as an additional measure of `distance' between a pair of candidate points in a matching algorithm by Relaxation Labeling (RL). The volume of the MP is related with the Epipolar Geometry and the use of this measure works as an epipolar constraint in a RL process, decreasing the efforts in the matching algorithm since it is not necessary to explicitly determine the equations of the epipolar lines and to compute the distance of a candidate point to each epipolar line. As at the beginning of the process the Relative Orientation (RO) parameters are unknown, a initial matching based on gradient, intensities and correlation is obtained. Based on this set of labeled points the RO is determined and the epipolar constraint included in the algorithm. The obtained results shown that the proposed approach is suitable to determine feature-point matching with simultaneous estimation of camera orientation parameters even for the cases where the pair of optical axes are not parallel.

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A new approach to solving the Optimal Power Flow problem is described, making use of some recent findings, especially in the area of primal-dual methods for complex programming. In this approach, equality constraints are handled by Newton's method inequality constraints for voltage and transformer taps by the logarithmic barrier method and the other inequality constraints by the augmented Lagrangian method. Numerical test results are presented, showing the effective performance of this algorithm. © 2001 IEEE.