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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.
21

A multi-disciplinary conceptual design methodology for assessing control authority on a hybrid wing body configuration

Garmendia, Daniel Charles 07 January 2016 (has links)
The primary research objective was to develop a methodology to support conceptual design of the Hybrid Wing Body (HWB) configuration. The absence of a horizontal tail imposes new stability and control requirements on the planform, and therefore requiring greater emphasis on control authority assessment than is typical for conceptual design. This required investigations into three primary areas of research. The first was to develop a method for designing an appropriate amount of redundancy. This was motivated widely varying numbers of trailing edge elevons in the HWB literature, and inadequate explanations for these early design decisions. The method identifies stakeholders, metrics of interest, and synthesizes these metrics using the Breguet range equation for system level comparison of control surface layouts. The second area of research was the development trim analysis methods that could accommodate redundant control surfaces, for which conventional methods performed poorly. A new measure of control authority was developed for vehicles with redundant controls. This is accomplished using concepts from the control allocation literature such as the attainable moment subset and the direct allocation method. The result is a continuous measure of remaining control authority suitable for use during HWB sizing and optimization. The final research area integrated performance and control authority to create a HWB sizing environment, and investigations into how to use it for design space exploration and vehicle optimization complete the methodology. The Monte Carlo Simulation method is used to map the design space, identify good designs for optimization, and to develop design heuristics. Finally, HWB optimization experiments were performed to discover best practices for conceptual design.
22

Generation of semantic layouts for interactive multidimensional data visualization / Geração de layouts semânticos para a visualização interativa de dados multidimensionais

Erick Mauricio Gomez Nieto 24 February 2017 (has links)
Visualization methods make use of interactive graphical representations embedded on a display area in order to enable data exploration and analysis. These typically rely on geometric primitives for representing data or building more sophisticated representations to assist the visual analysis process. One of the most challenging tasks in this context is to determinate an optimal layout of these primitives which turns out to be effective and informative. Existing algorithms for building layouts from geometric primitives are typically designed to cope with requirements such as orthogonal alignment, overlap removal, optimal area usage, hierarchical organization, dynamic update among others. However, most techniques are able to tackle just a few of those requirements simultaneously, impairing their use and flexibility. In this dissertation, we propose a set of approaches for building layouts from geometric primitives that concurrently addresses a wider range of requirements. Relying on multidimensional projection and optimization formulations, our methods arrange geometric objects in the visual space so as to generate well-structured layouts that preserve the semantic relation among objects while still making an efficient use of display area. A comprehensive set of quantitative comparisons against existing methods for layout generation and applications on text, image, and video data set visualization prove the effectiveness of our approaches. / Métodos de visualização fazem uso de representações gráficas interativas embutidas em uma área de exibição para exploração e análise de dados. Esses recursos visuais usam primitivas geométricas para representar dados ou compor representações mais sofisticadas que facilitem a extração visual de informações. Uma das tarefas mais desafiadoras é determinar um layout ótimo visando explorar suas capacidades para transmitir informação dentro de uma determinada visualização. Os algoritmos existentes para construir layouts a partir de primitivas geométricas são tipicamente projetados para lidar com requisitos como alinhamento ortogonal, remoção de sobreposição, área usada, organização hierárquica, atualização dinâmica entre outros. No entanto, a maioria das técnicas são capazes de lidar com apenas alguns desses requerimentos simultaneamente, prejudicando sua utilização e flexibilidade. Nesta tese, propomos um conjunto de abordagens para construir layouts a partir de primitivas geométricas que simultaneamente lidam com uma gama mais ampla de requerimentos. Baseando-se em projeções multidimensionais e formulações de otimização, os nossos métodos organizam objetos geométricos no espaço visual para gerar layouts bem estruturados que preservam a relação semântica entre objetos enquanto ainda fazem um uso eficiente da área de exibição. Um conjunto detalhado de comparações quantitativas com métodos existentes para a geração de layouts e aplicações em visualização de conjunto de dados de texto, imagem e vídeo comprova a eficácia das técnicas propostas.
23

Storage Format Selection and Optimization for Materialized Intermediate Results in Data-Intensive Flows

Munir, Rana Faisal 01 February 2021 (has links)
Modern organizations produce and collect large volumes of data, that need to be processed repeatedly and quickly for gaining business insights. For such processing, typically, Data-intensive Flows (DIFs) are deployed on distributed processing frameworks. The DIFs of different users have many computation overlaps (i.e., parts of the processing are duplicated), thus wasting computational resources and increasing the overall cost. The output of these computation overlaps (known as intermediate results) can be materialized for reuse, which helps in reducing the cost and saves computational resources if properly done. Furthermore, the way such outputs are materialized must be considered, as different storage layouts (i.e., horizontal, vertical, and hybrid) can be used to reduce the I/O cost. In this PhD work, we first propose a novel approach for automatically materializing the intermediate results of DIFs through a multi-objective optimization method, which can tackle multiple and conflicting quality metrics. Next, we study the behavior of different operators of DIFs that are the first to process the loaded materialized results. Based on this study, we devise a rule-based approach, that decides the storage layout for materialized results based on the subsequent operation types. Despite improving the cost in general, the heuristic rules do not consider the amount of data read while making the choice, which could lead to a wrong decision. Thus, we design a cost model that is capable of finding the right storage layout for every scenario. The cost model uses data and workload characteristics to estimate the I/O cost of a materialized intermediate results with different storage layouts and chooses the one which has minimum cost. The results show that storage layouts help to reduce the loading time of materialized results and overall, they improve the performance of DIFs. The thesis also focuses on the optimization of the configurable parameters of hybrid layouts. We propose ATUN-HL (Auto TUNing Hybrid Layouts), which based on the same cost model and given the workload and characteristics of data, finds the optimal values for configurable parameters in hybrid layouts (i.e., Parquet). Finally, the thesis also studies the impact of parallelism in DIFs and hybrid layouts. Our proposed cost model helps to devise an approach for fine-tuning the parallelism by deciding the number of tasks and machines to process the data. Thus, the cost model proposed in this thesis, enables in choosing the best possible storage layout for materialized intermediate results, tuning the configurable parameters of hybrid layouts, and estimating the number of tasks and machines for the execution of DIFs. / Moderne Unternehmen produzieren und sammeln große Datenmengen, die wiederholt und schnell verarbeitet werden müssen, um geschäftliche Erkenntnisse zu gewinnen. Für die Verarbeitung dieser Daten werden typischerweise Datenintensive Prozesse (DIFs) auf verteilten Systemen wie z.B. MapReduce bereitgestellt. Dabei ist festzustellen, dass die DIFs verschiedener Nutzer sich in großen Teilen überschneiden, wodurch viel Arbeit mehrfach geleistet, Ressourcen verschwendet und damit die Gesamtkosten erhöht werden. Um diesen Effekt entgegenzuwirken, können die Zwischenergebnisse der DIFs für spätere Wiederverwendungen materialisiert werden. Hierbei müssen vor allem die unterschiedlichen Speicherlayouts (horizontal, vertikal und hybrid) berücksichtigt werden. In dieser Doktorarbeit wird ein neuartiger Ansatz zur automatischen Materialisierung der Zwischenergebnisse von DIFs durch eine mehrkriterielle Optimierungsmethode vorgeschlagen, der in der Lage ist widersprüchliche Qualitätsmetriken zu behandeln. Des Weiteren wird untersucht die Wechselwirkung zwischen verschiedenen peratortypen und unterschiedlichen Speicherlayouts untersucht. Basierend auf dieser Untersuchung wird ein regelbasierter Ansatz vorgeschlagen, der das Speicherlayout für materialisierte Ergebnisse, basierend auf den nachfolgenden Operationstypen, festlegt. Obwohl sich die Gesamtkosten für die Ausführung der DIFs im Allgemeinen verbessern, ist der heuristische Ansatz nicht in der Lage die gelesene Datenmenge bei der Auswahl des Speicherlayouts zu berücksichtigen. Dies kann in einigen Fällen zu falschen Entscheidung führen. Aus diesem Grund wird ein Kostenmodell entwickelt, mit dem für jedes Szenario das richtige Speicherlayout gefunden werden kann. Das Kostenmodell schätzt anhand von Daten und Auslastungsmerkmalen die E/A-Kosten eines materialisierten Zwischenergebnisses mit unterschiedlichen Speicherlayouts und wählt das kostenminimale aus. Die Ergebnisse zeigen, dass Speicherlayouts die Ladezeit materialisierter Ergebnisse verkürzen und insgesamt die Leistung von DIFs verbessern. Die Arbeit befasst sich auch mit der Optimierung der konfigurierbaren Parameter von hybriden Layouts. Konkret wird der sogenannte ATUN-HL Ansatz (Auto TUNing Hybrid Layouts) entwickelt, der auf der Grundlage des gleichen Kostenmodells und unter Berücksichtigung der Auslastung und der Merkmale der Daten die optimalen Werte für konfigurierbare Parameter in Parquet, d.h. eine Implementierung von hybrider Layouts. Schließlich werden in dieser Arbeit auch die Auswirkungen von Parallelität in DIFs und hybriden Layouts untersucht. Dazu wird ein Ansatz entwickelt, der in der Lage ist die Anzahl der Aufgaben und dafür notwendigen Maschinen automatisch zu bestimmen. Zusammengefasst lässt sich festhalten, dass das in dieser Arbeit vorgeschlagene Kostenmodell es ermöglicht, das bestmögliche Speicherlayout für materialisierte Zwischenergebnisse zu ermitteln, die konfigurierbaren Parameter hybrider Layouts festzulegen und die Anzahl der Aufgaben und Maschinen für die Ausführung von DIFs zu schätzen.
24

Use of Electrical Coolant Pumps in Scania’s Cooling System / Användning av elektriska kylvätskepumpar i Scanias kylsystem

Srikanth, Sai Aswin January 2019 (has links)
The automotive industry is currently traversing through the electrification wave. Numerous manufacturers are directing focus to electrify their lineup and reduce emissions. In the frontier of heavy duty diesel trucks, electrification of auxiliary units remains an unexplored potential. An optimized cooling system functioning in sync with a controllable electric coolant pump attempts to reduce parasitic losses and emissions. The cooling flow requirements in challenging conditions may also be fulfilled. Although electric coolant pumps are found increasingly in passenger cars, the implication of independently operating them in a heavy duty diesel truck is an important objective to be explored. The purpose of this project is to generate different cooling system layouts coupled with electrical coolant pumps. The performance of these layouts is compared with the volume flows in a standard cooling system. Refined layouts which fulfill the cooling system requirements are chosen for verification. 1-D Simulation is used to correlate and verify the trends of the test rig data. The results show an adequate gain in the total volume flow across distinct layouts with the electric coolant pumps. However, numerous challenges are required to be overcome. / Bilindustrin befinner sig mitt i en våg av elektrifiering. Flertalet tillverkare fokuserar på att elektrifiera sitt produktutbud och att minska utsläppen. Inom forskningen kring tunga transporter med dieseldrivna lastbilar, är elektrifiering av kylsystemet ett outforskat område. Ett optimerat kylsystem som är reglerbart med en elektrisk kylvätskepump skulle potentiellt kunna minska energiförluster och utsläpp. Kravet på flödet av kylvätska vid utmanande driftsfall skulle också kunna bli bättre uppfyllda än för dagens system. Trots att det blir allt vanligare att personbilar har elektriska kylvätskepumpar, så har det inte utforskats vad det innebär att ha reglerbara elektriska kylvätskepumpar i dieseldriva lastbilar. Därför är detta ett viktigt område att utforska. Målet med detta projekt är att skapa olika kylsystemskoncept, där den elektriska kylvätskepumpen är en systemkomponent. Prestandan hos dessa principlösningar jämförs sedan med volymflödet i ett standard kylvätskesystem. Koncept som uppfyller kraven för kylvätskesystemet kommer att bli utvalda för vidare verifiering. 1-D simuleringar används för att hitta samband och verifiera mot trenderna som hittas i resultat från en testrigg. Resultaten visar en förbättring i det totala volymflödet för flera av lösningarna, som har en elektrisk kylvätskepump. Men det finns fortfarande flera utmaningar som behöver övervinnas.
25

Empirical Assessment of UML Class Diagram Layouts Based on Architectural Importance

Sharif, Bonita 19 April 2010 (has links)
No description available.
26

L'évolution du cadre juridique de protection de l'environnement en algérie / The evolution of legal framework of environnement

Saidane, Aness 08 June 2016 (has links)
Le droit de l'environnement a pour objet l'étude ou l'élaboration de règles juridiques concernant, la protection, l'utilisation, la gestion, la compréhension ou la restauration de l'environnement. La protection juridique de l'environnement est considérée comme un instrument mis en place par les sociétés pour interdire, orienter ou conseiller les comportements des administrations, des opérateurs économiques et des citoyens en vue de la protection des différents éléments de l'environnement. L’ Algérie commençait à s’intéresser à la dégradation de l’environnement depuis les années 80, La loi n°83-03 du 5 février 1983 relative à la protection de l'environnement repose sur des principes essentiels de protection de 1'environnement, notamment la protection contre les différentes nuisances et pollutions et sur l'intégration de la protection de l'environnement dans la planification nationale. Deux décennies après la promulgation de la loi de 1983, le constat est négatif et aucune amélioration notable n'a été enregistrée en matière de protection de l’environnement, comme, il ressort des travaux préparatoires de la loi relative à la protection de l'environnement promulguée en 2003 que l'Algérie ne possède pas une stratégie à la fois nationale et globale, en matière de protection de l'environnement, de nature à garantir une gestion efficace des ressources naturelles et leur protection contre toutes les formes de pollutions dues aux facteurs économiques, naturels et humains. La loi de 2003 marque ainsi une importante évolution législative, dans le domaine de la protection de 1'environnement. C'est dans ce cadre qu'a été adopté la loi n°03-10 du 19 juillet 2003 relative à la protection de 1'environnement dans le cadre de développement durable, dans un contexte international caractérisé par l'importance accordé aux problèmes de l'environnement à l'échelle mondiale. Cette loi a été élaborée sur la base des nouveaux principes internationaux régissant l'environnement et le développement et le développement durable. Parmi les objectifs de la loi figure également la détermination du rôle des différents intervenants dans le domaine de la protection de l'environnement, notamment l'administration publique et les opérateurs économiques. Donc le but recherché et de définir une politique environnementale et proposer des éléments et proposer des mesures institutionnelles et juridiques pour renforcer les capacités de leur prise en charge ensuite élaborer un cadre de l’environnement fondé, ou la notion de partage de responsabilité, et la participation de tous les acteurs économiques à son application. / The environmental law aims to study and to develop legal rules to protect, use, manage, understand or restore the environment. Algeria begins to be interested in degradation of environment since the 80's years. The law No. 83-03 of 5 February 1983 on the protection of the environment based on key principles of protection of environment including protection against various damages and pollution and on integration of environment protection into national planning. After two decades from the enactment of the law of 1983, the result is negative and no significant improvement was recorded in the field of environmental protection. The preparation work for the Law on environment protection enacted in 2003, revealed that Algeria does not have a strategy at both national and global conceming environment protection, such as ensure effective management of natural resources and their protection against all forms of pollution due to economic, natural and human factors. The Law of 2003 was an important legislative development in the field of protection of environment. In this context, was adopted the Law No. 03-10 of 19 July 2003 on protection of environment as part of sustainable development, in an international context characterized by the importance given to global problems of environment. Among the purposes of the law, there is also definition of the role of different stakeholders in the field of environment protection, including public administration and economic operators. The purpose is to define an environmental policy and propose elements and legal and institutional measures to strengthen the capacity of their taking care, then develop a framework of environmental basis, or a notion of shared responsibility, and participation of all economic actors to its application.
27

Search-Optimized Disk Layouts For Suffix-Tree Genomic Indexes

Bhavsar, Rajul D 08 1900 (has links) (PDF)
Over the last decade, biological sequence repositories have been growing at an exponential rate. Sophisticated indexing techniques are required to facilitate efficient searching through these humongous genetic repositories. A particularly attractive index structure for such sequence processing is the classical suffix-tree, a vertically compressed trie structure built over the set of all suffixes of a sequence. Its attractiveness stems from its linearity properties -- suffix-tree construction times are linear in the size of the indexed sequences, while search times are linear in the size of the query strings. In practice, however, the promise of suffix-trees is not realized for extremely long sequences, such as the human genome, that run into the billions of characters. This is because suffix-trees, which are typically an order of magnitude larger than the indexed sequence, necessarily have to be disk-resident for such elongated sequences, and their traditional construction and traversal algorithms result in random disk accesses. We investigate, in this thesis, post-construction techniques for disk-based suffix-tree storage optimization, with the objective of maximizing disk-reference locality during query processing. We begin by focusing on the layout reorganization in which the node-to-block assignments and sequence of blocks are reworked. Our proposed algorithm is based on combining the breadth-first layout approach advocated in the recent literature with probabilistic techniques for minimizing the physical distance between successive block accesses, based on an analysis of node traversal patterns. In our next step, we consider techniques for reducing the space overheads incurred by suffix-trees. In particular, we propose an embedding strategy whereby leaf nodes can be completely represented within their parent internal nodes, without requiring any space extension of the parent node's structure. To quantitatively evaluate the benefits of our reorganized and restructured layouts, we have conducted extensive experiments on complete human genome sequences, with complex and computationally expensive user queries that involve finding the maximal common substring matches of the query strings. We show, for the first time, that the layout reorganization approach can be scaled to entire genomes, including the human genome. In the layout reorganization, with careful choice of node-to-block assignment condition and optimized sequence of blocks, search-time improvements ranging from 25% to 75% can be achieved with respect to the construction layouts on such genomes. While the layout reorganization does take considerable time, it is a one-time process whereas searches will be repeatedly invoked on this index. The internalization of leaf nodes results in a 25% reduction in the suffix-tree space occupancy. More importantly, when applied to the construction layout, it provides search-time improvements ranging from 25% to 85%, and in conjunction with the reorganized layout, searches are speeded up by 50% to 90%. Overall, our study and experimental results indicate that through careful choice of node implementations and layouts, the disk access locality of suffix-trees can be improved to the extent that upto an order-of-magnitude improvements in search-times may result relative to the classical implementations.
28

Optimisation of dynamic and stochastic production scheduling systems after random disruptions

Mapokgole, Johannes Bekane 20 May 2013 (has links)
M. Tech. (Department of Industrial Engineering and Operations Management, Faculty of Engineering), Vaal University of Technology. / The current business environments in many companies are characterized by markets facing tough competitions, from which customer requirements and expectations are becoming increasingly high in terms of quality, cost and delivery dates, etc. These emerging expectations are even getting stronger due to rapid development of new information and communication technologies that provide direct connections between companies and their clients. As a result, companies should have powerful control mechanisms at their disposal. To achieve this, companies rely on a number of functions including production scheduling. This function has always been present within companies, but today, it is facing increasing complexities because of the large number of jobs that must be executed simultaneously. Amongst many factors, it is time driven. This study demonstrates that several disciplines can be married into one model (i.e. a unified model) to solve scheduling problems after disruptions, and clears the way for future multi-disciplinary research efforts. Scheduling problem is modeled as follows: Ito’s stochastic differential rule is used to analyse the time evolution of random or stochastic processes. Multifactor productivity is used to unify various disruption factors. Theory of line balancing is also employed to determine the required number of resources to minimize bottleneck. Reliability: disruptions are considered to be equivalent to system failure. The failure rate of the system is translated to the reliability of the system mathematically. The probabilities of failure are used as indicators of disruptions, and the theory of reliability is then applied. Bernoulli’s principle is also employed to relate pressure to production flow and aid in managing bottleneck situations. Results indicate that the amount of resources needed after disruption depends on the nature of disruption, and that the scheduler should plan to increase number of facilities following a trend that is only predicted by the nature of disruptions. It is also shown that disruption of one type may not greatly affect productivity of a certain company layout, whilst similar disruptions can have devastating effect on another type. It is further concluded that impacts of disruption are dependent on the type of company layouts.

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