• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 700
  • 456
  • 453
  • 241
  • 143
  • 93
  • 89
  • 66
  • 66
  • 57
  • 53
  • 15
  • 15
  • 10
  • 10
  • Tagged with
  • 2788
  • 323
  • 291
  • 248
  • 247
  • 242
  • 208
  • 186
  • 183
  • 183
  • 179
  • 176
  • 170
  • 148
  • 147
  • 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.
411

An heuristic approach for the improvement of aircraft departure scheduling at airports

Teixeira, Roberto de Barros January 1992 (has links)
This work considers the management in the short run of aircraft departures from their parking stands at major airports where traffic congestion is noticeable. At the ground level, congestion is patent when carefully designed departure time tables become unworkable, causing ever increasing delays which penalize heavily passengers, airlines and the airport surrounding community. The study is composed of two parts: First an overall analysis of the considered problem is performed to provide background knowledge and to display basic principles for the management of aircraft ground movements at modem airports. Physical components as well as current operational rules are discussed and their interdependence is revealed. A particular importance is given to new and foreseeable developments in communication and guidance technology which allow an improved prediction of runway occupancy times or gaps. Capacity issues are also discussed with respect to aircraft ground activities and the airfield capacity is analysed. This first part of the work ends with the description of levels of fuel consumption and of pollution emission by aircraft ground operations and thus shows the relevance of the problem considered in this study. The second part of this work is devoted to the design of a just-in-time clearance policy which should minimise environment, fuel and pollution levels and made possible a delay-free ground traffic for departing aircraft A mathematical formulation of the considered decision problem, characterized as a real time scheduling problem, is built up. Then possible solution strategies are appraised and an "ad hoc" heuristic solution algorithm is designed. This solution is first compared in theoretical terms with a First Come First Served policy showing that in an error-free situation the proposed solution cannot be worse than its competitor. Then a simulation study is performed which confirms in practical terms the above result The influence of the main design parameters of the solution algorithm on its performance are also examined giving some insights in relation to necessary communication and prediction aids. Finally, possible extensions of the proposed method and its integration in a global aircraft traffic management system are discussed.
412

Beset by secrecy and beleaguered by rivals : the Special Operations Executive and military operations in Western Europe 1940-1942, with special reference to Operation Frankton

Keene, Thomas Edward January 2011 (has links)
The intention of this thesis is to investigate the circumstances and background surrounding the early development and deployment of the Special Operations Executive (SOE), Britain's clandestine secret service created by Winston Churchill in 1940 to 'set Europe ablaze.' It will examine the climate in which SOE was created, the feasibility of the tasks it was expected to perform and the relationships it established with Churchill, the Cabinet Office, the Chiefs of Staff, the Foreign Office, the Admiralty and Army, the Secret Intelligence Service (SIS) and Combined Operations. It will examine how these organisations succeeded or failed to work towards a common wartime objective. The focus of the thesis is concerned primarily with the political moves and counter-moves in London that dominated the early years of SOE's six year existence. It will concentrate therefore upon 1940-1942, the critical early years before planning for the Second Front 'militarised' SOE's clandestine role. There is thus little reference to SOE in The Balkans, in Holland or the Middle East or to the actual deployment and modus operandi of SOE agents in the field. Their stories of courage and betrayal, of penetration, capture or evasion are mentioned only in so far as they illuminate the struggle to establish a wider SOE credibility in London. The single exception to this is Operation Frankton, the 'Cockleshell Heroes' raid on Bordeaux shipping in December 1942. The planning, execution and result of this raid were determined by Combined Operations' relationship with SOE and led to an outcome that was shaped by SOE's sense of secrecy, rivalry and political encirclement. This thesis will attempt to unravel those critical and complex relationships.
413

Finding Power Within the Language : - a securitization study of operation EUNAVFOR MED

Smith, Josefine January 2016 (has links)
This research paper takes departure from the contradictions of understandings regarding the purpose of operation EUNAVFOR Med, which operates in the Mediterranean aiming at disrupting the business model of human smugglers. The alteration of opinions concerns the question(s) regarding, to what extent the operation should be considered a securitization, and if so, of what? Research has consequently been drawn from the Copenhagen’s School theory of securitization, looking deeper into the involvement of the main actors in the operation, the EU, the human smugglers and the migrants, in order to identify if this operation could indeed be considered a securitization act. By placing the main actors of the operation in the center of the theoretical framework this research has been able to identify how this operation can be understood from a securitization theory and also what has been securitized. The methodological approach is based upon Norman Fairclough’s critical discourse analysis, framing both the structure and the analytical apparatus of the research paper, enabling an even broader understanding of the case. The result showed that there are indeed indicators demonstrating that operation EUNAVFOR Med could be considered a successful securitization of human smugglers. Also, in line with this operation, there are several indicators that shows how the EU has managed to pull a securitization move of migration, arguing that the migrants has formed an ‘uncontrolled problem’ for the EU.
414

Solutions for Dynamic Channel Assignment and Synchronization Problem for Distributed Wireless Multimedia System

Hong, SungBum 08 1900 (has links)
The recent advances in mobile computing and distributed multimedia systems allow mobile hosts (clients) to access wireless multimedia Data at anywhere and at anytime. In accessing multimedia information on the distributed multimedia servers from wireless personal communication service systems, a channel assignment problem and synchronization problems should be solved efficiently. Recent demand for mobile telephone service have been growing rapidly while the electro-magnetic spectrum of frequencies allocated for this purpose remain limited. Any solution to the channel assignment problem is subject to this limitation, as well as the interference constraint between adjacent channels in the spectrum. Channel allocation schemes provide a flexible and efficient access to bandwidth in wireless and mobile communication systems. In this dissertation, both an efficient distributed algorithm for dynamic channel allocation based upon mutual exclusion model, and an efficient distributed synchronization algorithm using Quasi-sink for wireless and mobile multimedia systems to ensure and facilitate mobile client access to multimedia objects are proposed. Algorithm's performance with several channel systems using different types of call arrival patterns is determined analytically. A set of simulation experiments to evaluate the performance of our scheme using message complexity and buffer usage at each frame arrival time.
415

Patienternas upplevelse av att vara vaken under operation : - en litteraturstudie

Österman, Veronica, Sofie, Hillman January 2017 (has links)
Bakgrund: Det blir allt vanligare att patienter opereras i vaket tillstånd med hjälp av regionalanestesi och detta har visat sig ge bättre återhämtning efter operationen. Det finns dock kunskapsluckor om hur dessa patienter upplever situationen i den intraoperativa fasen då till exempel miljön kan ge många olika sinnesintryck. Det är bland annat operationssjuksköterskans ansvar att tillsammans med operationsteamet se till att patienten upplever ett gott välbefinnande under pågående operation. Syfte: Att beskriva patienters upplevelser av att vara vaken under operation. Metod: En litteraturstudie baserat på kvalitativa samt kvantitativa artiklar valdes för att ge en överblick över samtida forskningsartiklar inom detta område. Artiklarna analyserades utifrån Evans innehållsanalys. Sjutton artiklar valdes där majoriteten blev kvalitativa artiklar då syftet handlar om upplevelser. Resultat: Resultatet påvisar att patienten önskar få information både före och under pågående operation för att minska oron, ångesten samt smärtan. Det hjälpte även att hålla någon i handen för att minska oron och ångesten. Musik kan även vara en hjälpande faktor för patienten att slappna av samtidigt som vissa kände att de tappade kontrollen om de fick lyssna på musik. För att patienten skulle känna sig delaktig visade resultatet att det var viktigt att etablera en god kommunikation. Slutsats: För att kunna ge god omvårdnad till de patienter som opereras i vaket tillstånd krävs det att operationssjuksköterskan ser patienten som en unik individ och får tid att anpassa sin omvårdnad för att säkerställa god vård.
416

Permanent establishment dilemma in the digital economy

13 October 2014 (has links)
M.Com. (South African and International Taxation) / The concept of permanent establishment (PE) is a fundamental concept in international tax law, as it establishes the right to tax business profits of non-resident entities in the country where business activities are carried out. This study was motivated by the challenges governments and business entities face in the allocation of taxing rights in the digital economy. This study considers the history and the meaning of the current Organisation for Economic Co-Operation and Development (OECD) permanent establishment concept, and analyses its effectiveness in the digital economy. The digital economy and the event of e-commerce have changed the way in which business transactions are conducted and how multinational entities are structured. The digital economy has created different means of value creation for business entities, and new challenges are being confronted internationally regarding the taxation of such value created. This directly affects revenue collection by governments globally. A largely qualitative approach was undertaken in conducting the research. This included a detailed reading on the topic to support any inferences and conclusions. This study finds that the current OECD concept of permanent establishment is no longer an effective concept in the current digital economy. The event of e-commerce is challenging the core elements of “physical presence” and “fixed place of business”. Large multinational entities have low effective tax rates on their profits, and governments are being deprived of tax revenue that would normally have resulted from increased productivity. Data and data collection are important value creators in the digital economy, and there is an increasing need to tax digital company profits. The OECD Base Erosion and Profit Shifting (BEPS) Project announced in 2013, means to address resultant issues, such as tax-base erosion, tax abuse, and artificial avoidance of permanent establishment status. This study concludes that either the concept of permanent establishment needs to be redefined to ensure its effectiveness in the digital economy, or a completely new concept needs to be created.
417

Operation barras : Kan principerna överraskning & Hastighet förklara det taktiska genomförandet?

Cidrér, Pontus January 2016 (has links)
On 10 September 2000, the British Special Forces conducted Operation Barras that aimed to free seven soldiers from the Royal Irish Regiment held hostage by a guerrilla group during the civil war in Sierra Leone. The problem that the study aims to explain is if the tactical execution was significant in the success of the operation and, if so, what was successful. The purpose of this study is to explain what made Operation Barras successful by studying its tactical execution. To do this, the principles of speed and surprise from McRavens theory of relative superiority have been used to conduct a qualitative case study. The results of the survey show that the principles are used and that they contributed to the success of the tactical execution. It was primarily the principle of surprise that could explain why the execution was successful. The principle of speed was used in the initial stage but this declined because of a strong-willed opponent. Those principles provide two perspectives on studying the operation and its complexity. The study can fill part of the gap found in research on what it was that made operation Barras successful and contribute to further understanding within the area of special operations.
418

Real-Time and Data-Driven Operation Optimization and Knowledge Discovery for an Enterprise Information System

Duan, Qing January 2014 (has links)
<p>An enterprise information system (EIS) is an integrated data-applications platform characterized by diverse, heterogeneous, and distributed data sources. For many enterprises, a number of business processes still depend heavily on static rule-based methods and extensive human expertise. Enterprises are faced with the need for optimizing operation scheduling, improving resource utilization, discovering useful knowledge, and making data-driven decisions. </p><p>This thesis research is focused on real-time optimization and knowledge discovery that addresses workflow optimization, resource allocation, as well as data-driven predictions of process-execution times, order fulfillment, and enterprise service-level performance. In contrast to prior work on data analytics techniques for enterprise performance optimization, the emphasis here is on realizing scalable and real-time enterprise intelligence based on a combination of heterogeneous system simulation, combinatorial optimization, machine-learning algorithms, and statistical methods. </p><p> </p><p>On-demand digital-print service is a representative enterprise requiring a powerful EIS.We use real-life data from Reischling Press, Inc. (RPI), a digit-print-service provider (PSP), to evaluate our optimization algorithms.</p><p>In order to handle the increase in volume and diversity of demands, we first present a high-performance, scalable, and real-time production scheduling algorithm for production automation based on an incremental genetic algorithm (IGA). The objective of this algorithm is to optimize the order dispatching sequence and balance resource utilization. Compared to prior work, this solution is scalable for a high volume of orders and it provides fast scheduling solutions for orders that require complex fulfillment procedures. Experimental results highlight its potential benefit in reducing production inefficiencies and enhancing the productivity of an enterprise.</p><p>We next discuss analysis and prediction of different attributes involved in hierarchical components of an enterprise. We start from a study of the fundamental processes related to real-time prediction. Our process-execution time and process status prediction models integrate statistical methods with machine-learning algorithms. In addition to improved prediction accuracy compared to stand-alone machine-learning algorithms, it also performs a probabilistic estimation of the predicted status. An order generally consists of multiple series and parallel processes. We next introduce an order-fulfillment prediction model that combines advantages of multiple classification models by incorporating flexible decision-integration mechanisms. Experimental results show that adopting due dates recommended by the model can significantly reduce enterprise late-delivery ratio. Finally, we investigate service-level attributes that reflect the overall performance of an enterprise. We analyze and decompose time-series data into different components according to their hierarchical periodic nature, perform correlation analysis,</p><p>and develop univariate prediction models for each component as well as multivariate models for correlated components. Predictions for the original time series are aggregated from the predictions of its components. In addition to a significant increase in mid-term prediction accuracy, this distributed modeling strategy also improves short-term time-series prediction accuracy. </p><p>In summary, this thesis research has led to a set of characterization, optimization, and prediction tools for an EIS to derive insightful knowledge from data and use them as guidance for production management. It is expected to provide solutions for enterprises to increase reconfigurability, accomplish more automated procedures, and obtain data-driven recommendations or effective decisions.</p> / Dissertation
419

The Trial of Harry Dexter White: Soviet Agent of Influence

Adams, Tom 17 December 2004 (has links)
The Red Scare of the late 1940s and 1950s was fueled by claims of governmental espionage from former members of the communist underground. Harry Dexter White, Assistant Secretary of the Treasury was accused of being a Soviet agent of influence. This paper will analyze the current issues in the discussion of Soviet espionage and focus on White's activities in this regard. The evidence on White is clear enough to show that he did pass sensitive information to the Soviets. He also succeeded in subverting American policy to favor Soviet interests over U.S. interests. White's activities in government service suggest that American government officials passed on vital government information to the Soviet Union and subversive activity went on in the U.S. in the 1930s and 1940s.
420

Relationship between the Sludge Settling Characteristics and the Parameters of the Activated Sludge System

Rojas, Jose Angel 17 December 2004 (has links)
The activated sludge process is one of the most commonly employed domestic and industrial waste treatment process. Different types of mathematical models have been proposed for design and operation of this process, most of which do not consider the relationship between the sludge settling characteristics and the aeration unit performance. This project studies the validity of a model developed by La Motta (2004b) which links the operating parameters of an activated sludge system and the classical limiting flux sludge settling theory. Favorable results were obtained demonstrating that the model predicts very similar values of the parameters of the system in comparison with the parameters observed in an activated sludge pilot plant that is located within installations of the Marrero Wastewater Treatment Plant, New Orleans, Louisiana. This research also demonstrated that the model is a helpful tool for the design and operation of an activated sludge system.

Page generated in 0.0694 seconds