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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.
41

Vliv provozního režimu traktoru na činnost systému selektivní katalytické redukce

Karásek, Tomáš January 2016 (has links)
This thesis called "Influence of an operation mode of a tractor on function of selective catalytic reduction system" describes various operation modes of the tractor, when aqueous solution of urea (AdBlue) was injected into selective catalytic reduction system. The first part jkdeals with particular pollutants in exhaust fumes. Formation of pollutants and their impact on humans and environment is described in this chapter. The second part describes individual technical systems used to lower harmful components, especially selective catalytic reduction system. The last part concentrates on practical measuring of operating parameters of the tractor, particularly consumption of aqueous solution of urea conducted in different modes of a motor. Part of the experimental measuring is graphic and verbal evaluation.
42

Estudo de viabilidade técnica aplicado ao desenvolvimento do conceito de plataforma ULFPSO com utilização de riser rígido em catenária livre. / Technical feasibility study applied to the ULFPSO platform concept with steel catenary riser.

Eduardo Marçal Vilameá 14 June 2017 (has links)
A exploração de bacias petrolíferas do pré-sal, principalmente campos gigantes como o campo de Libra, na bacia de Santos, traz consigo demandas por sistemas capazes de operar com poços de alta capacidade de produção e em grandes profundidades. Nesse cenário, linhas de produção ou injeção (risers) rígidas em catenária livre apresentam a forma mais simples de solução para essas demandas. A utilização de risers rígidos em catenária livre, como já sabido, permite uma maior produtividade por linha devido a possibilidade de utilização de dutos de maiores diâmetros, ao mesmo tempo em que resistem a maiores pressões, possibilitando a exploração de forma mais eficiente de poços em grandes profundidades. No entanto, este tipo de solução, devido a sua natureza de maior rigidez quando comparado com dutos flexíveis, é submetida a esforços dinâmicos elevados impostos no topo do riser pela grande movimentação da embarcação, principalmente em operações em águas profundas, inviabilizando sua aplicação em unidades do tipo FPSOs convencionais, construídos a partir da conversão de um navio petroleiro. Este problema dinâmico é agravado pelas condições ambientais da região, que são mais severas do que as observadas na Bacia de Campos, tornando difícil a aplicação das tecnologias existentes. A alta produtividade dos poços do pré-sal da Bacia de Santos também estimula a utilização de plantas de processo de alta capacidade de processamento de óleo, maiores do que as utilizadas até hoje no offshore brasileiro. Estimativas iniciais mostram que estas plantas gigantes demandam uma área de convés muito maior do que as plataformas convencionais, e, mais do que isso, de uma maior largura (boca) da embarcação. Para atender requisitos tão conflitantes, foi desenvolvido o conceito ULFPSO (Unidade Flutuante de Produção, Armazenamento e Alívio Ultra-Larga), que se caracteriza por sua proa e popa circulares e pela presença do moonpool, de forma a viabilizar a conexão dos risers mais próximos ao centro de gravidade da plataforma, reduzindo assim o esforço dinâmico. Adicionalmente a forma do casco é otimizada para redução do nível de movimentos verticais, reduzindo os esforços dinâmicos nos risers. Nesta dissertação de mestrado serão apresentados os estudos relativos à comprovação de viabilidade do conceito, dividido em três etapas: A primeira com foco no entendimento do problema e dimensionamento preliminar da unidade; A segunda focada na avaliação experimental do conceito; E finalmente, a terceira, com objetivo de avaliar o modelo de síntese para otimização do projeto do casco, com base nos resultados obtidos nas fases anteriores. / The offshore exploitation of oil fields in the pre-salt, especially giant fields such as Libra, in the Santos basin, brings with it demands for systems capable of operating with high capacity production wells and at ultra-deep waters. In this scenario production or injection steel catenary risers present the simplest solution for these demands. As known in industry, the use of steel catenary risers in free-hanging configuration allows greater productivity per line due to the possibility of using pipes of larger diameters, at the same time withstand higher pressures, allowing for more efficient wells operation at great depths. However, due to its nature more rigid compared to flexible pipe, this kind of solution is subjected to high dynamic forces imposed on the top of the riser by the large movement of the vessel, especially in deepwater operations, impeding their application in FPSO conventional units, constructed from the conversion of an oil tanker. This dynamic problem is compounded by environmental conditions of the region, which are harsher than those observed in the Campos Basin, making it difficult to apply other extant technologies. The high productivity of the pre-salt of Santos Basin wells stimulate the use of plants to high-capacity oil processing process, larger than those used today in the Brazilian offshore. Initial estimates show that these plants require a much larger deck area than conventional platforms and, more than that, a greatest width (breadth) of the vessel. To satisfy such conflicting requirements, the ULFPSO (Ultra Large Floating Production, Storage and Offloading) concept was developed, which is characterized by its circular bow and stern and the presence of the moonpool, to enable the connection of the risers closest to the platform\'s center of gravity, thereby reducing the dynamic tension. Additionally, the hull shape is optimized to reduce vertical movements, reducing dynamic stresses on the riser. In this master\'s thesis will be presented studies on the proof of concept viability, divided into three stages: The first focused on understanding the problem and preliminary sizing of the unit; The second focused on the experimental evaluation of the concept; And finally, the third, to evaluate the synthesis model for optimizing hull design, based on the results obtained in the previous phases.
43

Solvency II: solventnost v pojišťovnictví / Solvency II: solvency in insurance

Čáha, Pavel January 2017 (has links)
This thesis is dedicated to Solvency II, a regulatory framework for insurance and reinsurance companies effective in European Union. Firstly, it explains the notion solvency and also describes the principles of the regulation itself. Another part is focused on the calculation of solvency capital requirement and minimal capital requirement, using standard formula. The capital requirements are derived on the level of risk modules and their submodules. Furthermore, the topic of technical reserves is discussed and emphasis is placed on the derivation of mean square error of prediction. Described methods are Chain-Ladder and Bornhuetter-Ferguson. The last part of the thesis includes the calculation of capital requirements for real data. A program SolvencyII.xlsx that shows particular derivations is enclosed.
44

Study of SCR using Cu-Zeolite catalysts on a light-duty diesel engine under steady state and transient conditions

Gall, M. January 2015 (has links)
The recognition of the negative impact of NOx resulted in increasingly tighter automotive emission regulations. Companies are under pressure to develop methods, which can meet the legislative demands. After treatment solutions, and especially Selective Catalytic Reduction, became the focus of research and have shown so far promising results. However, more in depth understanding of the SCR process under different conditions is needed. This thesis describes an investigation of the SCR performance using gas and urea injections under steady state and transient conditions undertaken on a light duty diesel engine using a 1D exhaust system designed for uniform flow across the catalyst. Under steady state conditions, the SCR performance was examined for low and high temperature conditions. Ammonia was supplied either as 5% ammonia gas or in form of urea injection. The engine was operating at 1500 rpm and 6 and 8 bar BMEP to provide an exhaust gas temperature of 210 °C and 265 °C respectively. Also, the effect of SCR brick length on the NOx conversion was investigated using SCR catalysts of length 30, 45 and 75 mm. To measure the influence of NO2:NOx ratio on the SCR performance, different sizes of standard DOC were used. NH3:NOx dosage levels included; α~0.5 - deficient ammonia, α~1.0 - stoichiometric ammonia, α~1.25 - excess ammonia. Gas emissions were measured before and after the SCR catalysts with a Horiba FTIR analyser during steady state and long transient tests. It was found that conditions such as temperature and NO2:NOx had the biggest impact on the SCR performance. During the steady state engine conditions, at α~1.0 ammonia dosing and NO2:NOx ratio of 0, only 17% of NO was converted in the first 30 mm of the SCR brick length. The conversion was improved at high temperature (263 °C) to 31%. A fast response CLD analyser was used during short transient testing to sample emissions with a high resolution. The short transient test with standard 0.5 and 1 DOC, and fixed ammonia dosing, showed that NOx conversion was reduced during the ramp event due to deficient ammonia and a drop in the supplied NO2:NOx ratio. During urea injection experiments, urea was injected either through an oblique pipe arrangement with a mixer device placed downstream or directly into a mixing can. In this case the mixer device was replaced with a straight pipe. A 75mm SCR was fitted and to ensure that supplied NO2:NOx ratio was zero, a palladium only DOC was used post a DPF. It was found that a large proportion of urea decomposition and hydrolysis was occurring on the surface of the SCR catalyst. Comparing NOx performance between urea injection and ammonia gas dosing experiment, more NO was converted for a given NH3:NOx ratio when ammonia was supplied in the form of gas. That was true for low and high temperature tests. For most studies, a long 10 degree diffuser was used in front of the SCR to provide uniform gas distribution across the catalyst. In addition SCR performance was investigated with a 180 degree sudden expansion diffuser in order to measure the influence of temperature and velocity profiles. During this study, a 45 mm SCR catalyst was used to provide a moderate amount of NO conversion and ammonia slip. The results showed that the flow and temperature distribution upstream of the SCR catalyst will have an effect on the NOx conversion, and that gas velocity has bigger impact on NOx conversion than gas temperature.
45

Bosch DNOX 5.x - optimalizace zkoušek / Optimization of Bosch DNOX 5.x Pump Module Testing Matrix

Friedl, Michal January 2015 (has links)
Táto diplomová práca sa zaoberá optimalizáciou validačných testov pre produkt firmy Robert Bosch určený na úpravu výfukových plynov vznetových motorov, tzv. Denoxtronic 5.x, konkrétne jeho najkomplikovanejšiu časť – Pump Module. Zhrnutím a analyzovaním porúch objavujúcich sa v reálnej prevádzke tak poskytuje spätnú väzbu pre oddelenie vývoja a navrhuje, akým mechanizmom by mali byť v budúcnosti validačné testy optimalizované.
46

Modelování a návrh ESD ochran v integrovaných obvodech / Modelling and Design of the IC`s ESD Protection Structures

Běťák, Petr January 2009 (has links)
The thesis introduces new semiconductor structures that are used as protections against Electrostatic Discharge occuring in integrated circuits. The fundamental structure for modeling and simulation has been lateral Silicon Controlled Rectifier. This SCR structure has been modificated to enable tuning of the triggering and holding voltages by changing geometrical mask dimensions. On the base of modeling and simulation the new proposed structures have been published. Also several protection structures have been designed to be manufactured and measured on a testchip. The final electrical behavior has been verified by measurement. Finally, the focus has been aided to protection circuit with bipolar transistor. This approach has been also simulated and verified by measurement. Advantages and disadvantages of the proposed protection structures are commented in the thesis.
47

Studies on Transition Metal Oxide Catalysts for Waste Gas Treatment / 排ガス処理用遷移金属酸化物触媒に関する研究

Kuma, Ryoji 23 March 2021 (has links)
京都大学 / 新制・論文博士 / 博士(工学) / 乙第13403号 / 論工博第4189号 / 新制||工||1761(附属図書館) / (主査)教授 田中 庸裕, 教授 江口 浩一, 教授 阿部 竜 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
48

The Harmonic Distortion Reduction of Phase-Angle Fired SCRs Feeding a Resistive Load using Fuzzy Logic

Clark, Matthew A. 15 April 2010 (has links)
No description available.
49

REDOX CATALYSIS FOR ENVIRONMENTAL APPLICATIONS

Gawade, Preshit Vilas 13 August 2012 (has links)
No description available.
50

Kapitálové požadavky kladené na pojišťovny v Solvency II a jejich kvantifikace / Capital requirements for insurance companies under Solvency II and its quantification

Kožár, Martin January 2011 (has links)
This thesis studies project Solvency II, which is focused on the integrated regulation of insurance market in the European Union. It presents basic division and capital requirements arising from it. It describes division of the project into the three areas, refered to as pillars in practice. The thesis summarizes the basic methods for measuring the risk (Value at Risk, Tail Value at Risk), necessary in the calculation of the solvency capital requirements. The thesis studies the method of calculation of the solvency capital requirement SCR and the minimum capital requirement MCR. The calculation of the SCR is focused mainly on the method of the calculation of the capital requirement using the standard formula. Lastly, capital requirements are calculated using concrete data set.

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