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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.
631

Tupel von TVL als Datenstruktur für Boolesche Funktionen

Kempe, Galina 17 December 2009 (has links) (PDF)
In der vorliegenden Arbeit wird eine Datenstruktur zur Darstellung einer Booleschen Funktion "TVL-Tupel" präsentiert, die im Ergebnis einer Kombination der bekannten Datenstrukturen Entscheidungsgraph und Ternärvektorliste entsteht. Zuerst wird untersucht, wie lokale Phasenlisten sich als Elemente des Tupels eignen. Weiterhin wird die neue Dekompositionsart ("Tupel-Dekomposition") einer Boolesche Funktion in drei bzw. vier Teilfunktionen vorgestellt. Die Besonderheit der Teilfunktionen der Dekomposition besteht in ihrer Orthogonalität zueinander. Der Vorteil der Dekomposition von Funktionen mit einer hohen Anzahl von Konjunktionen besteht im geringeren Speicherplatzbedarf. Des weiteren wurden Algorithmen für Realisierung der Operationen entwickelt, die für eine Handhabung der zerlegten Funktionen erforderlich sind. Der detaillierte Vergleich der Berechnungszeiten für die Operationen erbringt den Nachweis, dass eine Verringerung des Zeitbedarfs als Folge der Zerlegung zu erwarten ist. Weiterhin bietet die Dekomposition einen Ansatz für den Entwurf von Algorithmen, die eine parallele Bearbeitung auf der Grundlage verteilter Rechentechnik zulassen. Die Erkenntnisse der Untersuchungen der Tupel-Dekomposition einschließlich der Verwendung der verteilen Verarbeitung können beispielsweise für die Suche der Variablenmengen der OR-Bi-Decomposition verwendet werden.
632

A Portable DARC Fax Service / En Bärbar Faxtjänst För DARC

Husberg, Björn January 2002 (has links)
<p>DARC is a technique for data broadcasting over the FM radio network. Sectra Wireless Technologies AB has developed a handheld DARC receiver known as the Sectra CitySurfer. The CitySurfer is equipped with a high-resolution display along with buttons and a joystick that allows the user to view and navigate through various types of information received over DARC. </p><p>Sectra Wireless Technologies AB has, among other services, also developed a paging system that enables personal message transmission over DARC. The background of this thesis is a wish to be able to send fax documents using the paging system and to be able to view received fax documents in the CitySurfer. </p><p>The presented solution is a central PC-based fax server. The fax server is responsible for receiving standard fax transmissions and converting the fax documents before redirecting them to the right receiver in the DARC network. The topics discussed in this thesis are fax document routing, fax document conversion and fax server system design.</p>
633

Designing Urban Road Congestion Charging Systems : Models and Heuristic Solution Approaches

Ekström, Joakim January 2008 (has links)
<p>The question of how to design a congestion pricing scheme is difficult to answer and involves a number of complex decisions. This thesis is devoted to the quantitative parts of designing a congestion pricing scheme with link tolls in an urban car traffic network. The problem involves finding the number of tolled links, the link toll locations and their corresponding toll level. The road users are modeled in a static framework, with elastic travel demand.</p><p>Assuming the toll locations to be fixed, we recognize a level setting problem as to find toll levels which maximize the social surplus. A heuristic procedure based on sensitivity analysis is developed to solve this optimization problem. In the numerical examples the heuristic is shown to converge towards the optimum for cases when all links are tollable, and when only some links are tollable.</p><p>We formulate a combined toll location and level setting problem as to find both toll locations and toll levels which maximize the net social surplus, which is the social surplus minus the cost of collecting the tolls. The collection cost is assumed to be given for each possible toll location, and to be independent of toll level and traffic flow. We develop a new heuristic method which is based on repeated solutions of an approximation to the combined toll location and level setting problem. Also, a known heuristic method for locating a fixed number of toll facilities is extended, to find the optimal number of facilities to locate. Both heuristics are evaluated on two small networks, where our approximation procedure shows the best results.</p><p>Our approximation procedure is also employed on the Sioux Falls network. The result is compared with different judgmental closed cordon structures, and the solution suggested by our method clearly improves the net social surplus more than any of the judgmental cordons.</p>
634

Morphologie des homéomorphismes des surfaces et méthodes géométriques en hydrodynamique

Kolev, Boris 08 June 2006 (has links) (PDF)
Les travaux présentés dans ce mémoire, portent essentiellement sur la théorie géométrique des systèmes dynamiques. Ils sont regroupés dans deux sections distinctes qui couvrent l'essentiel de mes recherches :<ul><li> L'étude de la dynamique et de la morphologie des homéomorphismes des surfaces,</li><li>L'utilisation de méthodes géométriques dans l'étude de certaines équations aux dérivées partielles apparaissant en mécanique et en hydrodynamique.</li></ul>Ce mémoire récapitule les travaux de dix-neuf articles groupés par thèmes et présentés dans l'ordre chronologique de leur élaboration.
635

CONTRIBUTIONS A L'ETUDE DES BOBINAGES SUPRACONDUCTEURS :<br />LE PROJET DGA DU SMES HTS IMPULSIONNEL

Bellin, Boris 29 September 2006 (has links) (PDF)
Dans le contexte d'un contrat de la Délégation Générale pour l'Armement (DGA) avec la société Nexans, le CRTBT-CNRS a développé une bobine supraconductrice de stockage d'énergie, ou SMES Superconducting Magnetic Energy Storage), avec des rubans PIT Bi-2212 pour un fonctionnement à 20 K. L'utilisation d'un bobinage supraconducteur permet de stocker l'énergie électrique sous forme magnétique sans conversion d'énergie, ceci pendant des temps très longs. Le bobinage stocke 800!kJ à décharger en 1 s pour atteindre une puissance de 500 kW sur la charge, ce qui génère une tension maximale de 5 kV. La cryogénie est réalisée avec des pièces en cuivre qui relient les cryoréfrigérateurs et le bobinage, avec différence de température de 2 K au maximum. L'interface HT (Haute Tension) entre les drains et le bobinage a une tenue diélectrique de 5 kV et permet de refroidir efficacement les amenées de courant et les 26 galettes, soit 40 km de ruban. L'énergie dissipée dans le cuivre et le bobinage pendant la décharge représente 1 l'énergie stockée. Des mesures thermiques à 20 K ont été réalisées sur des échantillons pour mesurer l'interface!HT par exemple, puis sur un bobinage de dimensions réduites pour valider les solutions retenues. Le procédé de coétamage des rubans supraconducteurs développés par Nexans permet d'adapter la géométrie du conducteur à sa situation dans le bobinage. Les essais des dix premières galettes bobinées a validé la cryogénie développée. L'étude d'extrapolation pour un SMES de 20 MJ présente une géométrie torique adaptée à un refroidissement par thermosiphon avec un câble bi-étagé Rutherford / 6+1 en fils ronds de Bi-2212.
636

THE SHORT GRIT SCALE: A DIMENSIONALITY ANALYSIS

Li, Caihong 01 January 2015 (has links)
This study aimed to examine the internal structure, score reliability, scoring, and interpretation of the Short Grit Scale (Grit-S; Duckworth & Quinn, 2009) using a sample of engineering students (N = 610) from one large southeastern university located in the United States. Confirmatory factor analysis was used to compare four competing theoretical models: (a) a unidimensional model, (b) a two-factor model, (c) a second-order model, and (d) a bi-factor model. Given that researchers have used Grit-S as a single factor, a unidimensional model was examined. Two-factor and second-order models were considered based upon the work done by Duckworth, Peterson, Matthew, and Kelly (2007), and Duckworth and Quinn (2009). Finally, Reise, Morizot, and Hays (2007) have suggested a bi-factor model be considered when dealing with multidimensional scales given its ability to aid researches about the dimensionality and scoring of instruments consisting of heterogeneous item content. Findings from this study show that Grit-S was best represented by a bi-factor solution. Results indicate that the general grit factor possesses satisfactory score reliability and information, however, the results are not entirely clear or supportive of subscale scoring for either consistency of effort subscale or interest. The implications of these findings and future research are discussed.
637

A cavity-backed coplanar waveguide slot antenna array

Mcknight, James W 01 June 2009 (has links)
In this thesis, a cavity-backed slot antenna array is designed for relatively wide instantaneous bandwidth, high gain and low sidelobes. The array consists of four, rectangular, slot elements, arranged side-by-side in a linear array and developed around 5GHz. Two feed points, at opposing sides of the printed array, each excite two of the slot elements through a series feed. This bidirectional feed presents symmetry to the design and prevents the tendency of beam-drift versus frequency as is common with many series-fed arrays. While being fed in-phase, the array will maintain boresight at broadside over the entire operating bandwidth. Also, the additional port allows for the potential introduction of a phase offset and, therefore, beam tilt. Finally, the printed array is designed to function within a quarter-wave, metallic cavity to achieve unidirectional radiation and improve gain.
638

Scheduling optimization of cellular flowshop with sequence dependent setup times

Ibrahem, Al-mehdi Mohamed M. 30 April 2014 (has links)
In cellular manufacturing systems, minimization of the completion time has a great impact on the production time, material flow, and productivity. An effective scheduling is crucial to attaining the advantages of cellular manufacturing systems. This dissertation attempts to solve the Flowshop Manufacturing Cell (cellular flowshop) Scheduling Problem with Sequence Dependent Setup Times (FMCSP with SDSTs) considering two performance measures: the total flow time as a mono objective, and the makespan and total flow time combined as a bi-criteria scheduling problem. The proposed problem is known to be the NP-hard problem because of its complexity. Several metaheuristic algorithms based on Genetic Algorithm (GA), Simulated Annealing (SA), and Particle Swarm Optimization (PSO) are developed for scheduling part families as well as jobs within each part family for FMCSP with SDSTs to minimize the total flow time. A local search method based on SA combined with PSO (named as PSO-SA) is proposed to enhance the intensification and improve the quality of the solution obtained by pure PSO. The effectiveness and efficiency of the proposed metaheuristics are evaluated based on the Relative Percentage Deviation (RPD) from its lower bound, and the robustness. Results indicate PSO-SA is performed similar to best available algorithms for small and medium size test problems. Yet, there is a very small deviation from best results for large problems. A Multi-objective Particle Swarm Optimization (MPSO) and a Multi-objective Simulated Annealing (MOSA) Algorithm are further proposed to solve the bi-criteria optimization problem to minimize the total flow time and makespan simultaneously. An improved PSO is combined with Threshold Acceptance (TA) algorithm to improve effectiveness of the proposed MPSO (named as IMPSO-TA) for the convergence of the obtained Pareto Front. The proposed algorithms are evaluated using several Quality Indicators (QI) measures for multiobjective optimization problems. The proposed algorithms can generate approximated Pareto Fronts in a reasonable CPU time. The proposed IMPSO-SA outperforms MOSA algorithm in terms of CPU time and minimizing the objective functions. / October 2015
639

Location and Capacity Modeling of Network Interchanges

Fabregas, Aldo D. 11 February 2013 (has links)
Network design decisions, especially those pertaining to urban infrastructure, are made by a central authority or network leader, and taking into consideration the network users or followers. These network decision problems are formulated as non-linear bi-level programming problems. In this work, a continuous network design problem (CNDP) and discrete network design problem (DNDP) bi-level optimization programs are proposed and solved in the context of transportation planning. The solution strategy involved reformulation and linearization as a single-level program by introducing the optimality conditions of the lower level problem into the upper level problem. For the CNDP, an alternative linearization algorithm (modified least squares partitioning, MLSPA) is proposed. MLSPA takes into consideration the current arc capacity and potential expansion to find a reduced set of planes to generalize the flow-capacity surface behavior. The concepts of flow capacity surface was introduced as a way to model of congested network and capture the effect of capacity on travel time/cost. It was found that the quality of the linear approximation depends on the goodness of fit the bottleneck arcs. The proposed approach was tested with well-known benchmark problems in transportation which yielded promising results in terms of efficiency, without sacrificing solution quality.
640

Assessing the influence of diagenesis on reservoir quality: Happy Spraberry Field, Garza County, Texas

Mazingue-Desailly, Vincent Philippe Guillaume 30 September 2004 (has links)
In the Permian Basin, strata of Leonardian age typically consist of interbedded carbonates and siliciclastics interpreted to be turbidite deposits. Happy Spraberry Field produces from a 100-foot thick carbonate section in the Lower Clear Fork Formation (Lower Leonardian) on the Eastern Shelf of the Midland Basin. Reservoir facies include oolitic- to-skeletal grainstones and packstones, rudstones and in situ Tubiphytes bindstones. Depositional environments vary from open marine reefs to shallow marine oolitic shoal mounds. Best reservoir rocks are found in the oolitic-skeletal packstones. Diagenesis occurred in several phases and includes (1) micritization, (2) stabilization of skeletal fragments, (3) recrystallization of lime mud, (4) intense and selective dissolution, (5) precipitation of four different stages of calcite cement, (6) mechanical compaction, (7) late formation of anhydrite and (8) saddle dolomite and (9) replacement by chalcedony. Oomoldic porosity is the dominant pore type in oolitic grainstones and packstones. Incomplete dissolution of some ooids left ring-shaped structures that indicate ooids were originally bi-mineralic. Bacterial sulfate reduction is suggested by the presence of (1) dissolved anhydrite, (2) saddle dolomite, (3) late-stage coarse-calcite cement and (4) small clusters of pyrite. Diagenetic overprinting on depositional porosity is clearly evident in all reservoir facies and is especially important in the less-cemented parts of the oolitic grainstones where partially-dissolved ooids were subjected to mechanical compaction resulting in "eggshell" remnants. Pore filling by late anhydrite is most extensive in zones where dissolution and compaction were intense. Finally, a porosity-permeability model was constructed to present variations in oolitic packstone- rudstone-bindstone reservoir rocks. The poroperm model could not be applied to oolitic grainstone intervals because no consistent trends in the spatial distribution of porosity and permeability were identified. Routine core analysis did not produce any reliable value of water saturation (Sw). An attempt to take advantage of wireline log data indicates that the saturation exponent (n) may be variable in this reservoir.

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