Ignition and combustion enhancement of lean homogeneous mixtures offers the potential to simultaneously lower pollutant emissions and improve the thermal efficiency of internal combustion engines. A single cylinder, high compression ratio (16.5:1), open chamber diesel engine has been converted to operate on homogenously charged compressed natural gas (CNG) with the aim of minimising pollutant emissions such as oxides of nitrogen, particulate matter and carbon dioxide. Three ignition systems were tested to examine how effectively they could ignite lean mixtures of CNG with the ultimate aim of achieving simultaneously high thermal efficiency and low oxides of nitrogen emissions. The ignition systems examined were spark ignition (SI), diesel pilot ignition (DPI) and hydrogen assisted jet ignition (HAJI). Irrespective of ignition system used, the efficiency of the engine operating on CNG was significantly reduced at part load compared to diesel. This was predominantly due to a greater amount of unburnt hydrocarbons, higher cycle-by-cycle variability, slow and partial burns and increased heat transfer to the walls. DPI and HAJI systems were able to extend the lean limit to lambda 2.7 and 3.3 respectively, however this did not result in efficiency gains over SI systems. HAJI proved to be superior to DPI with higher peak efficiency, lower carbon dioxide, carbon monoxide and particulates, and significantly lower oxides of nitrogen in the absence of a locally rich ignition source. (For complete abstract open document)

O tema do presente estudo consiste na análise da demanda do mercado de taxistas de Curitiba frente à possibilidade de utilização de um combustível alternativo menos oneroso e poluente: o Gás Natural Veicular – GNV. O objetivo principal deste trabalho foi de analisar o mercado atual do GNV entre os taxistas de Curitiba, verificando a possibilidade de ampliar do uso do GNV por esta frota através de uma pesquisa de mercado. Os dados da pesquisa servirão de subsídios para campanhas de marketing orientadas à ampliação acelerada do uso desta tecnologia. Para tanto, realizou-se uma pesquisa de satisfação para levantar os fatores determinantes para a tomada de decisão dos taxistas de Curitiba de utilizarem ou não um combustível alternativo menos oneroso e poluente como o Gás Natural Veicular – GNV. O estudo visou obter a percepção dos taxistas de Curitiba. Com base nos resultados da pesquisa foi possível estabelecer subsídios para campanhas de marketing orientadas à ampliação acelerada do uso desta tecnologia. Para realização da pesquisa, utilizou-se uma pesquisa exploratória, com entrevistas individuais da cúpula das organizações que trabalham com o Gás Natural, prospectando novos projetos para o futuro e as perspectivas de evolução do mercado de GNV em Curitiba, a qual forneceu subsídios para a pesquisa quantitativa junto aos taxistas da cidade de Curitiba. Constatou-se que somente 36% do público estudado é usuário de gás natural veicular, mas entre os não usuários, 82% já pensou em instalar o kit gás. As principais razões pelas quais os taxistas pesquisados não utilizam o GNV são a perda de espaço no porta-malas e a perda de potência do veículo. Entre os taxistas que utilizam o GNV, no que tange aos atributos relacionados à rede de distribuição, a maior insatisfação refere-se à localização dos postos e a maior satisfação às eventuais filas para abastecimento. Nesses mesmos atributos o que obteve maior índice de importância foi justamente a localização dos postos. Entre os atributos relacionados ao produto, o maior índice de satisfação foi o nível de poluição ambiental e a maior insatisfação espaço para armazenamento, sendo o desempenho do veículo considerado o mais importante. Quanto aos atributos relacionados aos equipamentos, verificou-se a segurança com o maior índice de satisfação e de importância. / The research was based on the following questions: What are the determinant factors for the taxi drivers’ decision on whether or not using a fuel that is less costly and polluting, such as the Compressed natural gas – CNG. The subject of this study consists of the analysis of the demand of the taxi drivers market towards the possibility of utilizing a less costly and polluting alternative fuel: the Compresses Natural Gas – CNG. The main objective of this paper was to analyze the current market of the taxi drivers of Curitiba, verifying the possibility of a unanimous use of the CNG by this fleet through market research. The data of the research will serve as subsidies for marketing campaigns directed to the accelerated increase of the utilization of this technology. For this reason a satisfaction survey was done to find the determinant factors for the decision of the taxi drivers of Curitiba to use or not a less costly and polluting alternative fuel such as the Compressed Natural Gas – CNG. The study aimed to get the feeling of the taxi drivers of Curitiba. Based on the results of the survey it was possible to establish subsidies for marketing campaigns for the accelerated increase of use of this technology. We used an exploratory research, with individual interviews of the heads of the organizations that work with the Compressed Natural Gas, trying to find out what their projects for the future are and the perspectives for the evolution of the CNG in Curitiba. This supplied subsidies for the quantitative research with the taxi drivers of Curitiba. We found out that only 36% of the segment use the compressed natural gas. Among the nonusers, 82% has already considered installing the gas kit. The main reasons for the taxi drivers not using the CNG are the loss of trunk space and of the power of the vehicle. Among the taxi drivers who use the CNG, in terms of the distribution net, the biggest complaint is about the localization of the service stations and the biggest satisfaction refers to the eventual fueling lines. Among these attributes, the one that obtained the highest rate of importance was the localization of the service stations. Among the attributes related to the product, the highest index of satisfaction was the level of environmental pollution, and the biggest complaint was the storage space, with the performance of the vehicle mentioned as the most important. As for the attributes related to the equipment, safety was the item with the highest index of satisfaction and importance.

This thesis deals with the introduction of alternative propulsion vehicles in a medium-sized enterprise. The starting point of the work is time series of fuel prices modelation: CNG gas, Natural 95 and Diesel during the years 2008--2013 and a two-year prediction of the prices, including the estimation of the uncertainty associated with the development of prices. The prediction is then used in simulations to estimate the probable development and effect of investments. The result of this thesis is formulated in a general methodology for the possible purchase of new cars in the midmarket and practical applications to mid-sized company MIKROP ČEBÍN a.s.

O tema do presente estudo consiste na análise da demanda do mercado de taxistas de Curitiba frente à possibilidade de utilização de um combustível alternativo menos oneroso e poluente: o Gás Natural Veicular – GNV. O objetivo principal deste trabalho foi de analisar o mercado atual do GNV entre os taxistas de Curitiba, verificando a possibilidade de ampliar do uso do GNV por esta frota através de uma pesquisa de mercado. Os dados da pesquisa servirão de subsídios para campanhas de marketing orientadas à ampliação acelerada do uso desta tecnologia. Para tanto, realizou-se uma pesquisa de satisfação para levantar os fatores determinantes para a tomada de decisão dos taxistas de Curitiba de utilizarem ou não um combustível alternativo menos oneroso e poluente como o Gás Natural Veicular – GNV. O estudo visou obter a percepção dos taxistas de Curitiba. Com base nos resultados da pesquisa foi possível estabelecer subsídios para campanhas de marketing orientadas à ampliação acelerada do uso desta tecnologia. Para realização da pesquisa, utilizou-se uma pesquisa exploratória, com entrevistas individuais da cúpula das organizações que trabalham com o Gás Natural, prospectando novos projetos para o futuro e as perspectivas de evolução do mercado de GNV em Curitiba, a qual forneceu subsídios para a pesquisa quantitativa junto aos taxistas da cidade de Curitiba. Constatou-se que somente 36% do público estudado é usuário de gás natural veicular, mas entre os não usuários, 82% já pensou em instalar o kit gás. As principais razões pelas quais os taxistas pesquisados não utilizam o GNV são a perda de espaço no porta-malas e a perda de potência do veículo. Entre os taxistas que utilizam o GNV, no que tange aos atributos relacionados à rede de distribuição, a maior insatisfação refere-se à localização dos postos e a maior satisfação às eventuais filas para abastecimento. Nesses mesmos atributos o que obteve maior índice de importância foi justamente a localização dos postos. Entre os atributos relacionados ao produto, o maior índice de satisfação foi o nível de poluição ambiental e a maior insatisfação espaço para armazenamento, sendo o desempenho do veículo considerado o mais importante. Quanto aos atributos relacionados aos equipamentos, verificou-se a segurança com o maior índice de satisfação e de importância. / The research was based on the following questions: What are the determinant factors for the taxi drivers’ decision on whether or not using a fuel that is less costly and polluting, such as the Compressed natural gas – CNG. The subject of this study consists of the analysis of the demand of the taxi drivers market towards the possibility of utilizing a less costly and polluting alternative fuel: the Compresses Natural Gas – CNG. The main objective of this paper was to analyze the current market of the taxi drivers of Curitiba, verifying the possibility of a unanimous use of the CNG by this fleet through market research. The data of the research will serve as subsidies for marketing campaigns directed to the accelerated increase of the utilization of this technology. For this reason a satisfaction survey was done to find the determinant factors for the decision of the taxi drivers of Curitiba to use or not a less costly and polluting alternative fuel such as the Compressed Natural Gas – CNG. The study aimed to get the feeling of the taxi drivers of Curitiba. Based on the results of the survey it was possible to establish subsidies for marketing campaigns for the accelerated increase of use of this technology. We used an exploratory research, with individual interviews of the heads of the organizations that work with the Compressed Natural Gas, trying to find out what their projects for the future are and the perspectives for the evolution of the CNG in Curitiba. This supplied subsidies for the quantitative research with the taxi drivers of Curitiba. We found out that only 36% of the segment use the compressed natural gas. Among the nonusers, 82% has already considered installing the gas kit. The main reasons for the taxi drivers not using the CNG are the loss of trunk space and of the power of the vehicle. Among the taxi drivers who use the CNG, in terms of the distribution net, the biggest complaint is about the localization of the service stations and the biggest satisfaction refers to the eventual fueling lines. Among these attributes, the one that obtained the highest rate of importance was the localization of the service stations. Among the attributes related to the product, the highest index of satisfaction was the level of environmental pollution, and the biggest complaint was the storage space, with the performance of the vehicle mentioned as the most important. As for the attributes related to the equipment, safety was the item with the highest index of satisfaction and importance.

O tema do presente estudo consiste na análise da demanda do mercado de taxistas de Curitiba frente à possibilidade de utilização de um combustível alternativo menos oneroso e poluente: o Gás Natural Veicular – GNV. O objetivo principal deste trabalho foi de analisar o mercado atual do GNV entre os taxistas de Curitiba, verificando a possibilidade de ampliar do uso do GNV por esta frota através de uma pesquisa de mercado. Os dados da pesquisa servirão de subsídios para campanhas de marketing orientadas à ampliação acelerada do uso desta tecnologia. Para tanto, realizou-se uma pesquisa de satisfação para levantar os fatores determinantes para a tomada de decisão dos taxistas de Curitiba de utilizarem ou não um combustível alternativo menos oneroso e poluente como o Gás Natural Veicular – GNV. O estudo visou obter a percepção dos taxistas de Curitiba. Com base nos resultados da pesquisa foi possível estabelecer subsídios para campanhas de marketing orientadas à ampliação acelerada do uso desta tecnologia. Para realização da pesquisa, utilizou-se uma pesquisa exploratória, com entrevistas individuais da cúpula das organizações que trabalham com o Gás Natural, prospectando novos projetos para o futuro e as perspectivas de evolução do mercado de GNV em Curitiba, a qual forneceu subsídios para a pesquisa quantitativa junto aos taxistas da cidade de Curitiba. Constatou-se que somente 36% do público estudado é usuário de gás natural veicular, mas entre os não usuários, 82% já pensou em instalar o kit gás. As principais razões pelas quais os taxistas pesquisados não utilizam o GNV são a perda de espaço no porta-malas e a perda de potência do veículo. Entre os taxistas que utilizam o GNV, no que tange aos atributos relacionados à rede de distribuição, a maior insatisfação refere-se à localização dos postos e a maior satisfação às eventuais filas para abastecimento. Nesses mesmos atributos o que obteve maior índice de importância foi justamente a localização dos postos. Entre os atributos relacionados ao produto, o maior índice de satisfação foi o nível de poluição ambiental e a maior insatisfação espaço para armazenamento, sendo o desempenho do veículo considerado o mais importante. Quanto aos atributos relacionados aos equipamentos, verificou-se a segurança com o maior índice de satisfação e de importância. / The research was based on the following questions: What are the determinant factors for the taxi drivers’ decision on whether or not using a fuel that is less costly and polluting, such as the Compressed natural gas – CNG. The subject of this study consists of the analysis of the demand of the taxi drivers market towards the possibility of utilizing a less costly and polluting alternative fuel: the Compresses Natural Gas – CNG. The main objective of this paper was to analyze the current market of the taxi drivers of Curitiba, verifying the possibility of a unanimous use of the CNG by this fleet through market research. The data of the research will serve as subsidies for marketing campaigns directed to the accelerated increase of the utilization of this technology. For this reason a satisfaction survey was done to find the determinant factors for the decision of the taxi drivers of Curitiba to use or not a less costly and polluting alternative fuel such as the Compressed Natural Gas – CNG. The study aimed to get the feeling of the taxi drivers of Curitiba. Based on the results of the survey it was possible to establish subsidies for marketing campaigns for the accelerated increase of use of this technology. We used an exploratory research, with individual interviews of the heads of the organizations that work with the Compressed Natural Gas, trying to find out what their projects for the future are and the perspectives for the evolution of the CNG in Curitiba. This supplied subsidies for the quantitative research with the taxi drivers of Curitiba. We found out that only 36% of the segment use the compressed natural gas. Among the nonusers, 82% has already considered installing the gas kit. The main reasons for the taxi drivers not using the CNG are the loss of trunk space and of the power of the vehicle. Among the taxi drivers who use the CNG, in terms of the distribution net, the biggest complaint is about the localization of the service stations and the biggest satisfaction refers to the eventual fueling lines. Among these attributes, the one that obtained the highest rate of importance was the localization of the service stations. Among the attributes related to the product, the highest index of satisfaction was the level of environmental pollution, and the biggest complaint was the storage space, with the performance of the vehicle mentioned as the most important. As for the attributes related to the equipment, safety was the item with the highest index of satisfaction and importance.

The aim of the studies included in the thesis is to better understand the interplay between neuronal activity-dependent gene regulation and the bioactive vitamin A metabolite all-trans-retinoic acid (RA) during postnatal development, refinement and maintenance of precise neuronal connectivity using the olfactory sensory neuron (OSN) in the olfactory epithelium (OE) of genetically modified mice as a model. We show that: Inhibition of RA receptor (RAR)-mediated transcription in OSNs reduces expression of the olfactory cyclic nucleotide-gated (CNG) ion channel, which is required for odorant receptor (OR)-mediated stimulus transduction. This, results in increased OSN death and errors in precise connectivity. The increased cell death may be a consequence of reduced intrinsic excitability and/or reduced influx of Ca2+ ions while the errors in connectivity may be due to altered OR-dependent expression of axonal guidance proteins, such as Kirrel-2 and Neuropilin-1. Expression of the RA catabolic enzyme Cyp26B1 in OSNs is positively regulated by RAR-mediated transcription as well as sensory stimulation in a CNG channel-dependent manner. This shows that neuronal activity and local vitamin A metabolism are parts of novel regulatory feedback loop controlling precise connectivity and neuronal survival. The feedback loop may be a form of homeostatic plasticity in response to global changes in neuronal activity. BACE1, an enzyme is implicated in Alzheimer´s disease, and Cyp26B1 are inversely regulated by CNG channel-dependent sensory stimulation. Cyp26B1 expression is switched on at birth, forms a topographic expression gradient in OE and inhibits BACE1 expression into an inverse counter gradient. Taken together these results reveal a novel neuronal activity-dependent mechanism by which sensory stimuli can shape spatial gene expression via altered RA bioavailability. Increased Cyp26B1 expression stimulates turnover of OSNs during adult neurogenesis by a non-cell-autonomous mechanism. The gradient of Cyp26B1 expression correlates with spatially-regulated diversification of OSNs into subpopulations that express different subsets of OR genes. Cyp26B1 expression influences spatial OR diversification of OSNs by two different mechanisms. In the ventrolateral OE, Cyp26B1 inhibits OR expression by blocking OSN differentiation at a stage that may be associated with the cell intrinsic mechanism regulating OR gene choice. In the dorsomedial OE the expression frequency of some ORs is unaltered while other increases, presumably as a consequence of neuronal activity-dependent competition. A probable function of graded and activity-dependent Cyp26B1 expression is to form a topographic partitioning of the olfactory sensory map into functional domains, which gradually differ from each other with regard to experience-driven plasticity and neurogenic potential along the dorsomedial-ventrolateral axis of OE.

The thesis deals with the topic of Carbon dioxide emissions that are created by Petrol, Diesel and CNG vehicles. In the first part of the thesis, the results of theoretical calculations are compared with the values of the manufacturer of the specific vehicle. In the second part, a specific method has been selected for calculations with real data from transport. The savings of CO2 produced by the specific vehicle are expressed in percentage – depending on the fuel used. The operating expenses from the real data are calculated and compared with hybrid and electric vehicles. In the final part of the thesis, the ratio of fleet type vehicles to the financial/ecological aspect was proposed.

The aim of diploma thesis is the design of fuel system for the Caterpillar twelve cylinder spark ignited turbocharged engine. The fuel system is designed for sequential electronic controlled gas injection into intake manifold. Computational model of the engine was calculated in Lotus Engine simulation software. CFD analysis of mixing CNG with air was computed in Star CCM+ software.

The master´s thesis is focused on the design of the multi-point CNG injection for the VW 1.4 TSI intake manifold turbocharged spark ignited engine. The 3D model that was created using Autodesk Inventor Professional 2012 is based on the real intake manifold. This model served as an input for CFD analyses of mixing CNG with air. These were made in STAR-CCM+ software.

This diploma thesis "The effect of CNG fuel combustion on the technical and economic parameters of the vehicle" deals with the use of alternative fuel of compressed natural gas for road vehicles. The thesis is divided into 4 main parts. In the first part there is a literary review, which deals with the history of the use of gaseous fuels in the world and in the Czech lands, as well as the characteristics and construction part of the car modified for CNG operation. The second part is an experimental measurement of performance parameters of two Škoda Octavia Combi III vehicles with a CNG, diesel and petrol engine at dynamometer testing laboratory, which is also described in this chapter. In the third part the results of experimental measurement are processed and commented and both vehicles are compared from the technical and economical point of view. As is evident from the measurement results, in a vehicle that is already equipped with CNG system from manufacturer combustion CNG does not have a negative effect on the engine's performance parameters and even more constant engine operation can be observed. Vehicles with CNG system are also more economical and ecological than vehicles combusting conventional fuels. The last part of this thesis is devoted to a discussion, where the measured results are compared with the results in an expert article dealing with the same topic.