• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 568
  • 322
  • 109
  • 82
  • 78
  • 49
  • 37
  • 22
  • 18
  • 18
  • 15
  • 8
  • 7
  • 6
  • 4
  • Tagged with
  • 1547
  • 504
  • 306
  • 278
  • 274
  • 173
  • 169
  • 160
  • 156
  • 152
  • 112
  • 109
  • 101
  • 94
  • 93
  • 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.
91

Ultrakurzzeitdynamik von Fulleriden in Lösung und suspendierten, längenselektierten Kohlenstoffnanoröhren

Brands, Helge January 2007 (has links)
Zugl.: Karlsruhe, Univ., Diss., 2007 / Hergestellt on demand. - Auch im Internet unter der Adresse http://uvka.ubka.uni-karlsruhe.de/shop/isbn/978-3-86644-211-5 verfügbar
92

Ultrakurzzeitdynamik von Fulleriden in Lösung und suspendierten, längenselektierten Kohlenstoffnanoröhren

Brands, Helge January 2007 (has links)
Zugl.: Karlsruhe, Univ., Diss., 2007
93

Emissionsdetektierte Femtosekunden-Spektroskopie an polyatomaren Molekülen

Nilsson, Qingrui An. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2004--München.
94

Ultraschnelle zeitaufgelöste Pump-Probe-Photoelektronenspektroskopie an isolierten und massenselektierten Anionen

Ehrler, Oli T. January 2006 (has links)
Zugl.: Karlsruhe, Universiẗat, Diss., 2006.
95

Projeto e construção de uma bomba de pistões axiais tipo Swashplate de vazão variável /

Azevedo, Glauco José Rodrigues de. January 2009 (has links)
Orientador: João Zangrandi Filho / Banca: João Alberto de Oliveira / Banca: Mauro Pedro Peres / Banca: Rosinei Batista Ribeiro / Banca: Gilbert Silva / Resumo: O desenvolvimento do projeto e a manufatura das máquinas de pistões axiais de vazão variável são atividades desenvolvidas por poucas empresas no mundo. Uma pesquisa para obter informações sobre o projeto deste tipo de equipamento, revelou pouquíssimas informações técnicas sobre este assunto. Talvez pela falta de uma literatura específica sobre o projeto e o funcionamento deste tipo de equipamento, as empresas brasileiras ainda não conseguiram desenvolver um projeto totalmente nacional. Este tipo de máquina tem grande aplicação na área industrial, móbile e aeronáutica. A importância do desenvolvimento deste trabalho justifica-se pela conquista de uma tecnologia dominada apenas por empresas estrangeiras, causando nas indústrias brasileiras que utilizam esta máquina, uma dependência tecnológica. Sendo assim, este trabalho visa oferecer às empresas brasileiras especializadas em bombas hidráulicas, informações sobre o funcionamento e também uma metodologia detalhada sobre o dimensionamento desta máquina. Calcular e desenhar uma determinada máquina não garante o seu perfeito funcionamento e também não assegura um sucesso sob o ponto de vista mercadológico. Portanto, foi realizado um estudo minucioso, além de uma discussão sobre o assunto com técnicos e engenheiros sobre a melhor forma de usinagem e montagem. Esta etapa precisa ser considerada tão importante quanto necessária. No desenvolvimento deste trabalho há uma apresentação sobre as bombas hidrostáticas disponíveis no mercado. Após a fundamentação teórica sobre o funcionamento da máquina swashplate, descrevendo detalhadamente cada um dos seus componentes, é apresentada uma metodologia para o dimensionamento dos principais parâmetros deste equipamento. Apresenta-se finalmente uma aplicação do método desenvolvido com um exemplo prático, discutindo os resultados alcançados. / Abstract: Designing and manufacturing of axial piston swashplate machines are activities that few companies have developed around the world. A research in order to obtain information about the design of this kind of machine has revealed only a small amount of technical bulletins. Maybe because of the lacking of a specific literature about designing and how this kind of machine works, brazilian industries have not yet developed a true national design. This machine has many application in the industrial, mobile and aeronautical area. How important this work is justified by the conquering of technology in a world where only foreign industries have it. In this way the present work offers to the brazilian industries that deals with hydraulics, information about how these machines run and a methodology teaching the way how to calculate the machine elements.. Calculating and drawing are not sufficient steps to have a machine running and are not a guarantee of success in the market too. That is why a detailed study, besides a discussing with machine operators and industry engineers was conducted in order to obtain better machining and assembling processes. This step must be considered as important as necessary. Therefore in the way to have this work accomplished, at first, the pumps available in the market are described. The work itself presents the theory related to this kind of machine, a way to explain how it works and describes in detail each part together with a methodology to calculate the machine main parameters. Finally an example of the application of the method is developed. / Doutor
96

Efficiency comparison between Heat Pump andMicro CHP located in two different location inSweden

Al-samuraaiy, Omar January 2016 (has links)
Efficiency of a ground source heat pump with thermal capacity of 6 kW determined in two differentlocations in Sweden. In the north side with low average temperature which could go down to -10 ᵒCand in the south side, with low average temperature with +2 ᵒC. The heat pump has refrigerantR407c, which could be connected to both, ground source heat feeding methods the horizontal, andthe vertical model. The heat pump give heat for both space heating and domestic hot watercompared the micro CHP which has thermal capacity of 12.5 kW and electrical capacity of 4.4 kW. Ithas IC engine which means the engine has internal combustion work. It also works with two kinds offuel, natural gas and propane MOZ 92; the energy and exergy of the fuel in micro CHP feeding thethermal process by heat. That heat used for space heating and domestic hot water after going outthe process for the cooling which keep the heat in storage tank and it heat the liquid to the gas to beused in the turbine to produce the electricity. The two locations in the north and south of Swedenwill influence the thermal operation and that influence power used for compressor for heat pumpand somehow the pump in the micro CHP. The study shows that the different in exergy and energyefficiency between these two heat technologies by located them in the locations. Higher efficiencyof the micro CHP which give the advantage of use Micro CHP some technology give the benefit byusing the fuel for producing the heating and electricity , the benefit which give the customer manybenefit shows in the study. That’s comparing with the heat pump which is large use in Sweden. Inthis paper will introduce Micro CHP as heating technology which has been used in the rest of Europecould be used in Sweden for future heating technology with electricity producing, shall change thecostumer from energy consumption costumer to producing costumer.
97

Ultrafast relaxation of hot phonons in graphene-hBN heterostructures

Golla, Dheeraj, Brasington, Alexandra, LeRoy, Brian J., Sandhu, Arvinder 01 May 2017 (has links)
Fast carrier cooling is important for high power graphene based devices. Strongly coupled optical phonons play a major role in the relaxation of photo-excited carriers in graphene. Heterostructures of graphene and hexagonal boron nitride (hBN) have shown exceptional mobility and high saturation current, which makes them ideal for applications, but the effect of the hBN substrate on carrier cooling mechanisms is not understood. We track the cooling of hot photo-excited carriers in graphene-hBN heterostructures using ultrafast pump-probe spectroscopy. We find that the carriers cool down four times faster in the case of graphene on hBN than on a silicon oxide substrate thus overcoming the hot phonon bottleneck that plagues cooling in graphene devices. (C) 2017 Author(s).
98

Efficacy of Dexmedetomidine Compared to Propofol in Pain Pump Placement Procedures

Haun,Cameron, Schwehr, Rebecca, Green-Boesen, Kelly, Boesen, Kevin January 2011 (has links)
Class of 2011 Abstract / OBJECTIVES: To compare the use of propofol to dexmedetomidine hydrochloride (Precedex®) in patients undergoing pain pump placements at University Physicians Hospital. METHODS: A retrospective chart review was performed evaluating anesthesia charts from December 2009 through February 2011. Heart rate (HR), blood pressure (BP), respiratory rate (RR), surgery time, and length of stay in the PACU were collected for both treatment groups. Demographic variables were also collected including age, sex, medical condition for which they are having a procedure performed, other co-morbid conditions and concurrent medications. RESULTS: Charts were reviewed for 8 dexmedetomidine patients and 16 propofol patients. There was no statistical difference among the groups with regard to demographics. The groups had similar procedural average systolic blood pressures, diastolic blood pressures, and heart rate (p = 0.93; p = 0.56, p = 0.37 respectively). The procedure time and recovery time in the PACU were similar between the dexmedetomidine group and propofol group (p = 0.52; p = 0.25, respectively). The endpoint respiratory rate was significantly lower in the propofol group (p = 0.05). There was no difference in additional sedative-analgesic medication use. CONCLUSION: Dexmedetomidine does not offer any clinical advantages to propofol when used as anesthesia for pain pump placement.
99

On site measurements of kraft pulp pump system efficiency

Kuhn, Reinaldo 05 1900 (has links)
With increasing energy costs and competitive pressures, interest has increased in surveying installed pumps for potential energy savings. Field pump efficiency tests are required to assess pumping performance and help to identify improvement opportunities. This work concerns the on-site measurements of pulp-suspension pumping efficiency. This involves the measurement of pump head, flow rate and power consumption. Provided that consistent flow measurements are available, it is possible to reliably and non-invasively measure actual pump system efficiencies in pulp suspension flow, with a minimum process disturbance. As part of a most appropriate measurement-procedure study, four portable nonintrusive flow meters were evaluated on site for pulp suspension flow. The Fast Fourier Transform Doppler was found to be the most suitable for a pulp mill pump survey. Efficiency measurements were performed on six pump systems with motors between 100 and 700 HP. It is shown that as-installed pump efficiency can be used to help predict the degradation of the pump and also its effect on the pumping system’s operation. A system approach analysis was performed in each case, which can be effective in assessing system performance and finding potential enhancements. The use of variable speed drives allows the operating point to move along the system curve, requiring less energy to drive the pump. VSD of larger motors are expensive and their profitability compared to other modification alternatives should always be carefully checked by calculations based on accurate on site measurements and life cycle costs. Finally, in this survey of six pump systems, significant potential savings of around 30% of present power consumption were found. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate
100

Strategies to Foster Appropriate Proton Pump Inhibitor Use

Thompson, Wade January 2017 (has links)
This thesis examines strategies to address the inappropriate proton pump inhibitor (PPI) use. A scoping review was conducted to examine patient preferences and values towards PPI initiation and continued treatment, as well as their attitudes towards reducing PPI use (deprescribing). Symptom control (reflux, heartburn) was a driver for patients to seek treatment. Patients were concerned about symptoms returning if they reduced their PPI use but were interested in using less medication if possible. Patients were open to discussing PPI reduction and valued clear communication about rationale and potential benefits/harms. As such, shared and informed decision-making (including eliciting patient values) is important in the choice to continue a PPI or try deprescribing. A decision-support tool for clinicians, aimed at the decision to continue a PPI versus try deprescribing, was implemented over 12 months in one long-term care home in Ottawa. The tool led to a non-statistically significant decrease in PPI use after it was implemented, but PPI usage began to gradually increase after six months. Strategies to sustain use of deprescribing initiatives are needed. Finally, a consult patient decision aid (PtDA) was developed and piloted in three Ottawa area clinics, and aimed to facilitate shared decision-making surrounding the decision to continue or try to reduce a PPI during a healthcare visit. Based on a sample of 12 patients, the consult PtDA increased knowledge about the decision and increased decisional confidence. After receiving the consult PtDA, 8/12 (75%) patients chose to reduce their PPI use and 4/12 (25%) chose to continue their PPI.

Page generated in 0.0307 seconds