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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.
281

[en] USE OF MULTIVARIED ANALYSIS TO DETERMINE THE GASOLINE COMPOSITION FROM THE FT-RAMAN SPECTROSCOPY AND GASEOUS CHROMATOGRAPHY / [pt] USO DE ANÁLISE MULTIVARIADA PARA DETERMINAR A COMPOSIÇÃO DE GASOLINA A PARTIR DA ESPECTROSCOPIA FT-RAMAN E CROMATOGRAFIA GASOSA

MARCOS ANTONIO GONZALEZ FERREIRA 15 June 2005 (has links)
[pt] A determinação de componentes da gasolina, e a contribuição destes na qualidade e desempenho final, tem levado há um grande número de estudos que possam criar rotinas para o monitoramento deste combustível. O objetivo deste trabalho é identificar e quantificar os principais grupos de compostos que compõem a gasolina comercial distribuída em parte da região sudeste, através de análise multivariada de dados de espectroscopia FT-Raman, através de regressão por Mínimos Quadrados Parciais (PLS - Partial Least Squares) e utilizando à análise dos componentes principais (PCA). Foram utilizadas 120 amostras aleatórias, do laboratório de combustíveis da PUC-Rio no período de janeiro a junho de 2004, as quais fazem parte do programa de controle de combustível. Todas as amostras foram submetidas à análise por cromatografia gasosa (CG) e espectroscopia FT-Raman no mesmo dia. Foram coletados todos os espectros FTRaman, e foram determinados a concentração dos principais grupos componentes da composição das gasolinas comerciais pelo método PONA/PEONA para parafinas(P), olefinas(O), naftênicos(N), aromáticos(A) e etanol(E). Os dados obtidos foram tratados por PLS/PCA de modo a se obter uma correlação de cada região específica dos espectros FT-Raman com os resultados obtidos por CG através dos métodos PONA/PEONA. / [en] The determination of the gasoline components, and the contribution of these in the quality and final performance, had in the past a great number of studies that can create routines for the monitoramento of this fuel. The objective of this work is to identify and to quantify the main groups of composites that compose the distributed commercial gasoline in part of the Southeastern region, through multivaried analysis of data of FT-Raman spectroscopy, through regression for Squared Minimums Partial (PLS - Partial Least Squares) using for the analysis of the main components (PCA), 120 random samples of the fuel laboratory of PUC-Rio in the period of January the June of 2004, which is part of the program of fuel control. All the samples had been submitted to the analysis for gaseous chromatography (GC) and FT-Raman spectroscopy in the same day. The FTRaman spectra had been all collected, and had been determined the concentration of the main component groups of the composition of the commercial gasolinas for method PONA/PEONA for paraffin(P), olefin(O), naphthene(N), aromatic(A) and ethanol(E). The experimental data had been treated by PLS/PCA in order to get a correlation of each specific region of the FT-Raman spectra with the results giving for GC through methods PONA/PEONA.
282

Experimental investigation of DME assisted gasoline CAI combustion with re-breathing valve strategy

Seo, Kangwoo January 2015 (has links)
Controlled auto-ignition (CAI), also known as HCCI combustion in a gasoline engine has been extensively researched due to their potential of improved engine efficiency and low NOx emission. However, the combustion timing and the phasing of conventional CAI combustion depend on the in-cylinder condition, such as temperature and combustible mixture strength and thus cannot be directly controlled. In this study, direct DME (Dimethyl Ether) injection was adopted to increase the ignitability of premixed gasoline/air charge and to trigger the auto ignition of premixed charge. Re-breathing valve strategies were used to obtain hot internal EGR to eliminate a need of intake heating. Firstly, the pilot valve opening event, including its opening and closing timing, valve lift and dwell duration between the main valve event, was analysed by the WAVE simulation. Based on the analysis a re-breathing cam lobe was manufactured and installed on a Ricardo E6 engine to achieve the intake rebreathing and exhaust rebreathing operations. The intake re-breathing was realised by the pilot intake valve opening during the exhaust stroke and the exhaust re-breathing was achieved by the secondary exhaust valve opening during the intake stroke. Effects of the pilot intake valve open timing, 2nd DME injection timing, split DME injection ratio, air/fuel ratio and compression ratio were examined during the intake rebreathing operation. Then the performance and emission characteristics of DME assisted gasoline CAI combustion were examined during the exhaust re-breathing operation. Finally, results of the intake and exhaust re-rebreathing operations were compared to the conventional SI operation. The experimental study found that both the intake and the exhaust re-breathing operations provided enough heat to initiate DME assisted gasoline CAI combustion. The direct DME injection enabled to control the start of combustion and phasing. The quantity of the first DME injection showed greater effect than its timing, whereas the injection timing of 2nd DME injection had more dominant effect than its quantity. The exhaust re-breathing strategy provided stratified and hotter internal EGR that does not impact negatively on the volumetric efficiency because exhaust gas was re-breathed from the exhaust port during the intake stroke. High load of both CAI and SI baseline operations were limited by knocking combustion and their low load were limited by incomplete combustion. Exhaust re-breathing operation extended substantially the operational range of the DME assisted gasoline CAI combustion. Extremely low NOx emissions were obtained by DME/gasoline CAI operations. Most importantly, the exhaust rebreathing method produced dramatically improved overall efficiency of 43% compared to 28% of SI operation at a typical part-load operation of 4.0-5.0bar IMEP. It was also found that slightly improved efficiency and the extended operation range could be obtained by 33%:67% split DME injection ratio at higher load, while 67%:33% split DME injection ratio at lower load.
283

Modélisation de la combustion et des polluants dans la ligne d'échappement d'un moteur / Modelling of the combustion and the polluants in the exhaust line of an IC-engine

Anderlohr, Jörg-Michel 16 December 2009 (has links)
L'objectif de ce travail de thèse est le développement d'un modèle numérique prédictif pour la simulation des phénomènes de postoxydation dans la ligne d’échappement d’un moteur à combustion interne. Le modèle a été écrit pour reproduire le processus d'auto inflammation des hydrocarbures durant la postoxydation, mais également l'évolution des polluants et des produits de combustion en général. Ceci a nécessité de mettre au point un schéma cinétique détaillé qui tienne compte de la chimie à basse température des hydrocarbures et de l'influence sur cette chimie des différentes espèces majeures présentes dans les gaz brûlés à postoxyder. Ces espèces sont le CO2, le H2O et le N2, qui agissent comme diluants, mais également des polluants tels que le CO ou les NOx. Ces derniers, même en faibles concentrations, peuvent avoir un effet important sur l’oxydation des hydrocarbures qui doit aussi être prise en compte dans le modèle chimique.Afin de considérer, en plus de la chimie, et les phénomènes physiques de la postoxydation, tels que la turbulence et les effets de mélange, ce schéma cinétique a été couplé à un modèle de combustion turbulente adapté à l'utilisation dans un code CFD 3D moteur. Ce couplage a été effectué via une tabulation a priori de la chimie, méthode qui permet de réduire considérablement le temps de calcul, tout en décrivant l'ensemble des phénomènes liés à la chimie détaillée. Une technique de tabulation de la cinétique chimique a donc été développée et implantée dans un code CFD. Une configuration permettant de représenter les phénomènes caractéristiques de la postoxydation dans la ligne d'échappement d'un moteur à combustion interne a été simulée. Les résultats permettent de mieux appréhender ces phénomènes et de proposer des solutions technologiques visant à leur optimisation / The aim of this PhD thesis is the development of a predictive numerical model capable of simulating hydrocarbon postoxidation in an IC engine exhaust line. The model should reproduce the auto-ignition of hydrocarbons, as well as the evolution of pollutants and combustion products under postoxidation conditions. For this purpose, a detailed kinetic reaction model was developed. It should be valid at low temperatures and under highly diluted conditions. The model should also take into account the effects of the major components of engine exhaust gas on hydrocarbon postoxidation. These are CO2, H2O, and N2, acting as diluting species, but also CO and NOx, which even in small amounts, may strongly impact hydrocarbon oxidation kinetics. These species must hence be considered for postoxidation modelling.In order to gather chemical and physical effects such as turbulence and mixing, the chemical kinetic mechanism was coupled with a turbulent combustion model designed for CFD 3D engine computations. An a priori tabulation methodology was developed, minimizing computational effort and the developed tabulation technique was validated under postoxidation conditions in an IC-engine exhaust line. The coupled chemical kinetics tabulation and turbulent mixing model was implemented in the CFD code IFP-C3D. Simulations were performed on a configuration representative of the physical phenomena characteristic of hydrocarbon postoxidation in exhaust lines. Results improved the understanding of postoxidation phenomena in an IC-engine exhaust line and propose technical solutions for an enhanced postoxidation control
284

[en] CAVITY RING-DOWN SPECTROSCOPY AS A TOOL FOR THE DETERMINATION OF CARBON ISOTOPE DISTRIBUTION / [pt] ESPECTROSCOPIA DE CAVIDADE RESSONANTE DO TIPO RING-DOWN (CRDS) COMO FERRAMENTA PARA A DETERMINAÇÃO DA DISTRIBUIÇÃO ISOTÓPICA DE CARBONO

JULIANNA MARIA DE ALMEIDA MARTINS 14 January 2013 (has links)
[pt] A análise isotópica vem crescendo a cada ano devido à sua grande área de atuação nas diversas áreas da ciência. Existem diversas técnicas utilizadas para realizar a determinação das concentrações naturais dos isótopos e suas variações, sendo que a mais utilizada é a espectrometria de massa de razões isotópicas (EMRI). Uma técnica analítica que vem ganhando espaço no mercado é a espectroscopia de cavidade ressonante do tipo ring-down (ECRRD) (Cavity Ring-Down Spectroscopy - CRDS), que é uma técnica baseada em laser. Ao contrário dos espectrômetros de massa, estes analisadores exigem pouco ou nenhum tratamento da amostra, diminuindo com isso o tempo de análise. O presente trabalho tem como objetivo obter a assinatura isotópica 13C/12C em amostra sólidas e líquidas, empregando um analisador a laser. Foi desenvolvido e implementado um método de análise isotópica empregando um analisador de carbono orgânico total acoplado a um espectrômetro de cavidade ressonante do tipo ring-down (iTOC-CRDS). Os resultados obtidos foram comparados com os obtidos através de um EMRI. O desempenho do método foi avaliado através dos parâmetros de linearidade; exatidão, pela utilização de materiais de referência certificados; precisão, pela repetitividade e reprodutibilidade; além dos cálculos das incertezas associadas. Foram analisadas amostras de açúcar, biomassas, bio-óleo, biocombustível, metanol e gasolina. / [en] The use of isotopic analyses grows each year, due to large area of expertise in several science areas. Several techniques are used to perform the determination of natural isotope concentrations and their variations, with isotopic ratio mass spectroscopy (IRMS) being the most widely used. An analytical technique that is gaining market space is the cavity ring-down spectroscopy. Unlike mass spectrometers, these analyzers require little or no sample treatment, thereby reducing the analysis time. The present study aimed to obtain the 13C/12C isotopic signature in solid and liquid samples using a laser analyzer. An isotopic analysis method using a total organic carbon analyzer coupled to a cavity ring-down spectrometer (iTOC-CRDS) was developed and implemented. The results were compared with those obtained by IRMS. The method performance was evaluated by the parameters of linearity; accuracy, using standard reference materials; precision, using parameters of repeatability and reproducibility and by calculating the associated uncertainties. The analyzed samples were sugar, biomass, bio-oil, biofuel, methanol and gasoline.
285

Diagnostická jednotka pro motorku / The motorcycle diagnostic unit

Smola, Tomáš January 2018 (has links)
This thesis deals with problematics of air/fuel mixture diagnosis od older carburetor motors. Especially for motors with more than one cylinder. In this thesis are informations about commercial product for diagnosis, brief informations about function of CV caburetor and best setup of fuel mixture. The next step in this thesis will be design, construction and testing of device for the diagnosis air/fuel mixture in practical use. Device will be able to measure mixture and other values witch can be used for best carburetor setup.
286

Implementación y operación de una Estación de Servicio

Alcántara Villanueva, Walter Manuel, Alvarado Villar, Karim Verónica, García Narváez, Paul Adolfo, Mikkelsen Siete, Rene José Joaquin, Toiro Zegarra, Aldo Valdomero 07 April 2021 (has links)
En la actualidad se observa que la venta de vehículos nuevos de transporte pesado, en particular los camiones y tractocamiones, en enero y febrero de 2021 tuvieron un crecimiento de 22.7% respecto al mismo periodo del 2020, en una coyuntura en la que diversas actividades ligadas al transporte de bienes, insumos y mercancías continuaron operando con relativa normalidad pesar de la pandemia. De otro lado, la comercializaron de unidades de vehículos livianos observó una contracción anual del 17% como consecuencia del comportamiento del consumidor frente al aumento del número de casos de COVID-19, nuevas medidas de restricción dictadas por el Gobierno para contener el avance de la segunda ola, y un mercado laboral que se recupera lentamente. Inversiones Estrella S.A.C. es una empresa que busca incursionar en el sector, para ello cuenta con socios con capacidad de solvencia necesaria para iniciar el negocio de operar una EDS ubicada en la Panamericana Sur, dado que se ha analizado el sector. El presente proyecto propone la creación de una propuesta de valor diferenciada y centrada en: precios bajos y atención al cliente. La inversión inicial es S/ 440,695, (100% capital social), determinando un COK de 11.9%, por lo que luego de la evaluación económico-financiera se obtiene un VAN positivo, una TIR mayor al COK y un periodo de recuperación dentro del periodo de análisis. Por tanto, se concluye que el proyecto es viable, por lo que se recomienda su implementación. / At present it is observed that the sale of new heavy transport vehicles, in particular trucks and tractors, in January and February 2021 had a growth of 22.7% compared to the same period of 2020, in a situation in which various related activities transportation of goods, supplies and merchandise, continued to operate with relative normality despite the pandemic. On the other hand, the commercialization of light vehicle units observed an annual contraction of 17% as a consequence of consumer behavior in the face of the increase in the number of COVID-19 cases, new restriction measures dictated by the Government to contain the advance of the second wave, and a slowly recovering labor market. Inversiones Estrella S.A.C. is a company that seeks to enter the sector, for this it has partners with the necessary solvency capacity to start the business of operating an EDS located in the Panamericana Sur, since the sector has been analyzed. This project proposes the creation of a differentiated value proposition focused on: low prices and customer service. The initial investment is S / 440,695, (100% capital stock), determining a COK of 11.9%, so after the economic-financial evaluation a positive NPV is obtained, an IRR greater than the COK and a recovery period within the Analysis period. Therefore, it is concluded that the project is viable, so its implementation is recommended. / Trabajo de investigación
287

Benzen v benzinech z hlediska ochrany zdraví / Benzene in petroleum-derived products and health protection

Bílková, Karolina January 2008 (has links)
Benzene is very toxic compound, which has carcinogenic and mutagenic effects. Result of these effects is significant reduction of its use and also low hygienic limits in occupational environment and environment. The aim of this diploma thesis was to map out possible exposure to benzene and checking of clasification correctness of motor gasoline and benzine (cleaners, thinners etc.). Determination of benzene was carried out by gas chromatography with flame ionisation detector (GC/FID) and high performance liquid chromatography with diod array detector (HPLC/DAD). Marginally, the diploma thesis was focused on determination of toluene (in june 2007 became effective ordinance no.284/2006 Sb., which forbid to sell products that contain more than 0,1 % of toluene to small consumers). Toluene was determined by same methods as benzene.
288

Contribution à l'étude de l'impact de la cavitation sur les processus physiques de l'atomisation primaire des jets d'injecteurs essence / Contribution to the cavitation impact study on the physical processes of jet primary atomization for gasoline direct injection

Makhlouf, Samir 20 May 2015 (has links)
Afin de se rapprocher des conditions du mélange homogène du moteur essence, plusieurs fluides sont injectés dans l'atmosphère à une pression amont et une température variées. Cinq prototypes d'injecteurs réels trois-trous de Continental ont été utilisés. En augmentant la pression d'injection, l'écoulement passe par quatre régimes où le niveau de développement de cavitation varie. Le coefficient de décharge Cd dépend essentiellement du nombre de cavitation. Au point critique de cavitation, deux corrélations ont été obtenues reliant respectivement Cd et le nombre de cavitation critique au nombre de Reynolds correspondant. Le jet en champ proche est gouverné par trois nombres sans dimensions : celui de Weber, de Reynolds et de cavitation. L'effet de chacun d'eux sur l'angle du jet à la sortie a été obtenu. La comparaison des résultats entre deux injecteurs a montré que le rapport entre la longueur et le diamètre de l'orifice est d'une influence d'ordre 1 sur l'angle du jet. / In order to get closer to the homogeneous mixture conditions of a gasoline engine, different fluids are injected into the atmosphere at varying upstream pressure and temperature. Five three-hole real injector prototypes from Continental were used. When injection pressure is increased, the internal flow goes through four regimes where the cavitation development level varies from one to another. The discharge coefficient Cd was found mainly dependent on the cavitation number. At the cavitation critical point, two correlations between Cd and the critical cavitation number on one side respectively, and the correspondent Reynolds number on the other side were found. The near field jet is ruled by three dimensionless numbers : Weber, Reynolds and cavitation. The effect of each one of them on the jet angle at the orifice outlet was obtained. By comparing the results of two injectors, it was found that the length over diameter ratio has a first order influence on the jet angle.
289

Är tanken halvfull eller halvtom? : En kvalitativ studie kring hur dagstidningarnas ledarskribenter framställer Bensinupproret 2.0. / Is the tank half full or half empty? : A qualitative study of how editorials at daily newspapers frame The Gasoline Uprising 2.0.

Edgren, Karl, O'Rourke Drevfjäll, Noah January 2020 (has links)
The purpose of this bachelor thesis was to examine how Swedish opinion journalists chose to portray The Gasoline Uprising 2.0, from both a framing perspective and a perspective of modes of persuasion. The research questions examined were: How does opinion journalists at Swedish daily newspapers frame The Gasoline Uprising 2.0? How does opinion journalists at Swedish daily newspapers use modes of persuasion in opinion pieces about The Gasoline Uprising 2.0?  The methods used in this bachelor thesis were a self made method that we based on Robert M. Entmans existing theory regarding framing. We also used a theory based on Karlberg and Mrals rhetoric method of analysis concerning the perspective modes of persuasions. A mix of these methods were used to examine how Swedish opinion journalists chose to frame The Gasoline Uprising 2.0. By examining the opinion pieces we found a variety of patterns. One of the main frame patterns pointed towards the writers feelings regarding compassion and understanding towards people that live in the countryside. Primarily the writers chose to frame The Gasoline Uprising 2.0 as an issue regarding the increasing polarization between the countryside and the city. The findings concerning the use of modes of persuasion showed that the writers primarily used compassion to increase their credibility during the use of ethos in the opinion pieces. Regarding logos we found that several writers used underlaying causes and compared the Swedish environmental politics to other countries in order to get people behind their thesis. From a pathos perspective, we found that the writers wanted to awaken feelings of empathy and anger within the reader.
290

CONVERSION OF POLYOLEFIN WASTE INTO FUELS AND OTHER VALUABLE PRODUCTS BY HYDROTHERMAL PROCESSING

Kai Jin (7040480) 07 May 2021 (has links)
Plastic waste is accumulated in landfills and the environment at an exponentially increasing rate. Currently, about 350 million tons of plastic waste is generated annually while only 9% is recycled. Plastic waste and its degradation products, microplastics, pose a severe threat to the ecosystem and eventually human health. Polyolefin (Polyethylene (PE) and Polypropylene (PP)) waste is 63% of the total plastic waste. Converting polyolefin waste into useful products including clean gasoline, diesel, wax, and monomers, via hydrothermal processing (HTP) can help reduce the plastic waste accumulation. In this study, sorted PE waste was converted via supercritical water liquefaction (SWL) into gasoline blendstock, No.1 ultra-low-sulfur diesel, and clean waxes with high yields and high purities. Comprehensive reaction pathways for PE conversion were proposed based on detailed GC×GC analyses. Furthermore, a new low-pressure (~2 MPa) hydrothermal processing (LP-HTP) method was developed to convert mixed polyolefin waste. This new LP-HTP method can save 90% of the capital cost and energy compared to SWL. The oil products were distilled into clean gasoline and No.1 ultra-low-sulfur diesel. The reaction pathways of PE and PP were independent while the synergistic effects improved the fuel qualities. With this LP-HTP method, polyolefin waste can be converted into up to 190 million tons of fuels globally, while 92% of the energy and 71% of the GHG emissions can be saved compared to conventional methods for producing fuels. Overall, this method is robust, flexible, energy-efficient, and environmental-friendly. It has a great potential for reducing the polyolefin waste accumulation in the environment and associated risks to human health.<br>

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