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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.
51

Calibration of fundamental diagrams for travel time predictions based on the cell transmission model

Seybold, Christoph January 2015 (has links)
Road traffic increases constantly and the negative consequences in the form of traffic jams can be realized especially in urban areas. In order to provide real time traffic information to road users and traffic managers, accurate computer models gain relevance. A software called Mobile Millennium Stockholm (MMS) was developed to estimate and predict travel times and has been implemented on a 7km test stretch in the north of Stockholm. The core of the software is the cell transmission model (CTM) which is a macroscopic traffic flow model based on aggregated speed observations. This thesis focuses on different calibration techniques of the so called fundamental diagram as an important input factor to the CTM. The diagrams illustrate the mathematical function which defines the relation between traffic flow, density and speed. The calibration is performed in different scenarios based on the least square (LS) and total least square (TLS) error minimization. Furthermore, sources, representing the traffic demand, and sinks, representing the surrounding of the modeled network, are implemented as dynamic parameters to model the change in traffic behavior throughout the day. Split ratios, as a representation of the drivers‘ route choice in the CTM are estimated and implemented as well. For the framework of this work, the MMS software is run in a pure prediction mode. The CTM is based on the source, sink, split and fundamental diagram parameters only and run forward in time. For each fundamental diagram calibration scenario an independent model run is performed. The evaluation of the scenarios is based on the output of the model. The results are compared to existing Bluetooth travel time measurements for the test stretch, which are used as ground truth observations, and a mean average percentage error (MAPE) is calculated. This leads to a most reasonable technique for the fundamental diagram calibration – the total least square error minimization.
52

Real time highway traffic prediction based on dynamic demand modeling

Bernhardsson, Viktor, Ringdahl, Rasmus January 2014 (has links)
Traffic problems caused by congestion are increasing in cities all over the world. As a traffic management tool traffic predictions can be used in order to make prevention actions against traffic congestion. There is one software for traffic state estimations called Mobile Millennium Stockholm (MMS) that are a part of a project for estimate real-time traffic information.In this thesis a framework for running traffic predictions in the MMS software have been implemented and tested on a stretch north of Stockholm. The thesis is focusing on the implementation and evaluation of traffic prediction by running a cell transmission model (CTM) forward in time.This method gives reliable predictions for a prediction horizon of up to 5 minutes. In order to improve the results for traffic predictions, a framework for dynamic inputs of demand and sink capacity has been implemented in the MMS system. The third part of the master thesis presents a model which adjusts the split ratios in a macroscopic traffic model based on driver behavior during congestion.
53

Thermally Conductive Polymer Composites for Electronic Packaging Applications

Khan, Muhammad Omer 20 July 2012 (has links)
Advancements in the semiconductor industry have lead to the miniaturization of components and increased power densities, resulting in thermal management issues. In response to this shift, finding multifunctional materials with excellent thermal conductivity and tailored electrical properties are becoming increasingly important. For this research thesis, three different studies were conducted to develop and characterize thermally conductive polymer composites. In the first study, a PPS matrix was combined with different types of carbon-based fillers to determine the effects of filler’s size, shape, and orientation on thermal conductivity. In the second study, effects of adding ceramic- and carbon- based fillers on the tailored thermal and electrical properties of composites were investigated. Lastly, the possibility of improving the thermal conductivity by introducing and aligning polymer fibers in the composites was investigated. The composites were characterized with respect to their physical, thermal, and electrical properties to propose possibilities of application in the electronic packaging industries.
54

Thermally Conductive Polymer Composites for Electronic Packaging Applications

Khan, Muhammad Omer 20 July 2012 (has links)
Advancements in the semiconductor industry have lead to the miniaturization of components and increased power densities, resulting in thermal management issues. In response to this shift, finding multifunctional materials with excellent thermal conductivity and tailored electrical properties are becoming increasingly important. For this research thesis, three different studies were conducted to develop and characterize thermally conductive polymer composites. In the first study, a PPS matrix was combined with different types of carbon-based fillers to determine the effects of filler’s size, shape, and orientation on thermal conductivity. In the second study, effects of adding ceramic- and carbon- based fillers on the tailored thermal and electrical properties of composites were investigated. Lastly, the possibility of improving the thermal conductivity by introducing and aligning polymer fibers in the composites was investigated. The composites were characterized with respect to their physical, thermal, and electrical properties to propose possibilities of application in the electronic packaging industries.
55

Fouling in silicon microchannel designs used for IC chip cooling and its mitigation /

Perry, Jeffrey L. January 2008 (has links)
Thesis (Ph.D.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 170-176).
56

Investigation of the long term physiological response of Huon pine (Lagarostrobos franklinii) to changes in atmospheric CO2 and climate using stable isotopes

Pepper, David A. January 1999 (has links)
Thesis (Ph. D.)--University of Sydney, 2000. / Title from title screen (viewed February 12, 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Biological Sciences, Faculty of Science. Degree awarded 2000; thesis submitted 1999. The 2 in the title is in subscript. Includes bibliographical references. Also available in print form.
57

Fabrication and characterization of nanostructured surfaces for enhanced heat transfer /

Choi, Changho. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 69-73). Also available on the World Wide Web.
58

Single-phase liquid flow and heat transfer in plain and enhanced silicon microchannels /

Steinke, Mark E. January 2005 (has links)
Thesis (Ph.D.)--Rochester Institute of Technology, 2005. / Typescript. Includes bibliographical references (leaves 179-189).
59

Experimental study of flow boiling heat transfer and critical heat flux in microchannels /

Kuan, Wai Keat. January 2006 (has links)
Thesis (Ph.D.)--Rochester Institute of Technology, 2006. / Typescript. Includes bibliographical references (leaves 270-275).
60

Desenvolvimento de massas cerâmicas para grés sanitários utilizando resíduo de vidro plano como fundente em substituição parcial ao feldspato.

CAVALCANTI, Maria do Socorro Lopes. 21 September 2018 (has links)
Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-09-21T20:55:37Z No. of bitstreams: 1 MARIA DO SOCORRO LOPES CAVALCANTI – DISSERTAÇÃO (PPGEP) 2010.pdf: 3984539 bytes, checksum: 9f61ce1d3e54382bd0b138b1af04b9b9 (MD5) / Made available in DSpace on 2018-09-21T20:55:37Z (GMT). No. of bitstreams: 1 MARIA DO SOCORRO LOPES CAVALCANTI – DISSERTAÇÃO (PPGEP) 2010.pdf: 3984539 bytes, checksum: 9f61ce1d3e54382bd0b138b1af04b9b9 (MD5) Previous issue date: 2010 / A preocupação com o meio ambiente tem sido a mola propulsora para reavaliação de vários dos processos produtivos em toda a sociedade. A população mundial tem se voltado para os conceitos de sustentabilidade e desta forma vários segmentos ligados à ciência e tecnologia vem buscando alternativas para controlar ou minimizar danos causados pelo consumo indiscriminado de matéria-prima e energia, além do alto volume de resíduos gerados. Nesta perspectiva este trabalho teve como objetivo estudar a possibilidade da incorporação de resíduos de vidro plano, oriundos das vidraçarias e do lixão de Campina Grande/PB, em massas cerâmicas para grés sanitários em substituição parcial ao feldspato. As matérias-primas foram caracterizadas através dos ensaios de análise química; análise granulométrica; difração de raios-X; espectroscopia vibracional de absorção no infravermelho; termogravimetria e análise térmica diferencial. Foram formuladas através do programa REFORMIX massas cerâmicas sem e com resíduos de vidro plano nos percentuais de 5%, 7% e 10%, e posteriormente avaliadas suas propriedades reológicas. Os corpos cerâmicos foram inicialmente secados em estufa a 110ºC, e em seguida queimados nas temperaturas de 1.000ºC, 1.100ºC, 1.200ºC e 1.250ºC. Foram caracterizados os corpos cerâmicos através dos seguintes ensaios físicomecânicos: absorção de água; porosidade aparente; massa específica aparente; ensaio de flexão em três pontos e retração linear, todos seguindo as recomendações de Sousa Santos e as normas da ABNT. Os resultados evidenciaram que os corpos cerâmicos obtidos com resíduos de vidro plano apresentaram propriedades físicomecânicas que atendem os padrões recomendados para uso em grés sanitários, sendo tecnologicamente viável a sua utilização. / The concern with the environment has been the propeller spring for reevaluation of several of the productive processes in all the society. The world-wide population has if come back toward the concepts of sustainability and thus some segments related to science and technology it comes searching alternatives to control or to minimize damages caused by the indiscriminate consumption of raw materials and energy, beyond the high volume of generated residues. In this perspective this work had as objective to study the possibility of the incorporation of plan glass residues, deriving of the glass factories and the landfills of Campina Grande/PB, in ceramic masses for sanitary stonewares in partial substitution to the feldspar. The raw materials were characterized through the assays of Chemical Analysis; Grain Sized Analysis; X-ray Diffraction; Vibrational Spectroscopy of the Infrared Absorption; Termogravimetry and Differential Thermal Analysis. Were formulated through program REFORMIX ceramic masses with and without plain glass residues in the percentages of 5%, 7% and 10%, and posteriorly evaluated its rheological properties. The ceramic bodies were initially dried in heater at 110ºC, and after burned at temperatures of 1000ºC, 1100ºC, 1200ºC and 1250ºC. We characterized the ceramic bodies through the following assays physicist-mechanics: water absorption; apparent porosity; apparent specific mass; assay of flexion in three points and linear retraction, all following the recommendations of Sousa Santos and the norms of the ABNT. The results evidenced that the ceramic bodies obtained with plain glass residues presented physicist-mechanical properties that attend the recommended patterns for use in sanitary stonewares, being technologically viable its use.

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