The main goal of this economic paper is to analyse the importance of LPG as an alternative fuel for the vehicular transport in the Czech Republic and to simplify the decision of potential applicants about the conversion of a car engine to run on LPG. At first this text briefly describes the main kinds of alternative fuels. Then the text focuses on LPG itself that is defined and described including its application in the past and at present. The next section of this paper is concentrated on the individual decision about the conversion of his car engine to run on LPG and the main attention will be focused on the environmental, economic, technical and institutional aspects of this conversion. Then the text compares LPG and CNG because CNG could be considered to be the main competitor of LPG in the field of alternative fuels. At the conclusion the paper summarizes the discovered facts and tries to predict future use of LPG as an alternative fuel in the Czech Republic.

Besides attenuation, dispersion is the major limiting factor in high data rate fiber optical transmission systems. Dispersion compensation techniques have to be deployed in order to increase the data bandwidth or the reach of fiber optical links. Typically fixed value dispersion compensators are used. However at channel bit rates of 40 GBit/s and beyond adjustable residual dispersion compensator modules (DCM) are needed to guarantee an error free transmission under changing environmental conditions. In this thesis dispersion techniques were investigated which exploit the special propagation properties of higher order modes in custom-designed optical fibers. After a short introduction of state-of-the-art dispersion techniques and their parameters (chapter 2) the modeling and calculation of propagation properties of a particular mode in an optical fiber with an arbitrary, rotation-symmetric refractive index profile is shown (chapter 3). A converter from the fundamental mode and back is needed in order to exploit the propagation properties of a higher order mode (HOM). In this work long-period gratings (LPG) were considered as mode converters (chapter 4) as they can excite selective and nearly lossless a higher order mode. The modeling und calculation of these gratings, based on the fiber calculation of chapter 3, is presented in the first part of chapter 4. Afterwards the manufacturing methods developed during this work are introduced. The spectral properties of realized long-period gratings are discussed and the influence of such factors as strain and temperature on tuning the mode conversion is shown. A dispersion compensator type utilizing only the waveguide dispersion of a certain mode in a custom few mode fiber (FMF) is the subject of chapter 5. The working principle, the fiber design process and first measurements of a realized HOM-DCM with almost completely coupling FMF-LPG are presented. Subsequently the principle of a novel dispersion compensator with an arbitrary dispersion function for a higher or the fundamental mode is explained. In chapter 6 another type of dispersion compensator is investigated consisting of equally distributed long-period gratings along an optical fiber. The fiber pieces between the gratings create a certain time delay between the fundamental mode and the considered higher order mode. It is shown in simulations and in an experiment, that by tuning the mode conversion of each grating and the optical phase relation between the two signal paths in each fiber piece this finite impulse filter structure is so adjusted to function as a tunable residual dispersion compensator.

Besides attenuation, dispersion is the major limiting factor in high data rate fiber optical transmission systems. Dispersion compensation techniques have to be deployed in order to increase the data bandwidth or the reach of fiber optical links. Typically fixed value dispersion compensators are used. However at channel bit rates of 40 GBit/s and beyond adjustable residual dispersion compensator modules (DCM) are needed to guarantee an error free transmission under changing environmental conditions. In this thesis dispersion techniques were investigated which exploit the special propagation properties of higher order modes in custom-designed optical fibers. After a short introduction of state-of-the-art dispersion techniques and their parameters (chapter 2) the modeling and calculation of propagation properties of a particular mode in an optical fiber with an arbitrary, rotation-symmetric refractive index profile is shown (chapter 3). A converter from the fundamental mode and back is needed in order to exploit the propagation properties of a higher order mode (HOM). In this work long-period gratings (LPG) were considered as mode converters (chapter 4) as they can excite selective and nearly lossless a higher order mode. The modeling und calculation of these gratings, based on the fiber calculation of chapter 3, is presented in the first part of chapter 4. Afterwards the manufacturing methods developed during this work are introduced. The spectral properties of realized long-period gratings are discussed and the influence of such factors as strain and temperature on tuning the mode conversion is shown. A dispersion compensator type utilizing only the waveguide dispersion of a certain mode in a custom few mode fiber (FMF) is the subject of chapter 5. The working principle, the fiber design process and first measurements of a realized HOM-DCM with almost completely coupling FMF-LPG are presented. Subsequently the principle of a novel dispersion compensator with an arbitrary dispersion function for a higher or the fundamental mode is explained. In chapter 6 another type of dispersion compensator is investigated consisting of equally distributed long-period gratings along an optical fiber. The fiber pieces between the gratings create a certain time delay between the fundamental mode and the considered higher order mode. It is shown in simulations and in an experiment, that by tuning the mode conversion of each grating and the optical phase relation between the two signal paths in each fiber piece this finite impulse filter structure is so adjusted to function as a tunable residual dispersion compensator.

Für PEM-Brennstoffzellen-Mikro-BHKW mit integrierter Dampfreformierung ist die Verwendung von LPG (Liquefied Petroleum Gas) bei fehlender Erdgasinfrastruktur interessant. Grundlage der BHKW-Effizienz ist eine optimale wärmetechnische Verschaltung, durch die u.a. das LPG/H2O-Gemisch effektiv auf die Reaktionstemperatur (700 °C) der Dampfreformierung vorgewärmt wird. In Abhängigkeit von der Verweilzeit, der das Gemisch ausgesetzt wird, können signifikante Mengen ungesättigter Kohlenwasserstoffe (C3H6, C2H4, C2H2) pyrolytisch gebildet werden, C3H6 kann des Weiteren bereits im LPG enthalten sein. Bei der katalytisch unterstützten Dampfreformierung fördert dies die Bildung verschiedenartiger kohlenstoffhaltiger Ablagerungen, wodurch eine vorzeitige Deaktivierung eintritt. In der Arbeit wird das Spaltpotenzial numerisch und experimentell untersucht. Durch Anwendung von Temperatur-Programmierter-Methanisierung und Ramanspektroskopie wird ferner der negative Einfluss bereits geringer C3H6-Anteile an einem Katalysator gezeigt. Aus den Ergebnissen werden abschließend Maßnahmen zur Minimierung kohlenstoffhaltiger Ablagerungen abgeleitet. / The use of LPG (Liquefied Petroleum Gas) is an alternative for PEM fuel cell micro-CHP systems with integrated steam reforming in the absence of natural gas infrastructure. An optimized thermo technical interconnection is the basis of the CHP efficiency, whereby, among other things, the LPG/H2O-mixture is preheated to the steam reforming reaction temperature (700 °C). Significant amounts of unsaturated hydrocarbons (C3H6, C2H4, C2H2) can be formed pyrolytically depending on the residence time for preheating the mixture; furthermore, C3H6 can be already a component of LPG. These species promote the formation of different carbon containing deposits on the reforming catalyst whereby a premature deactivation occurs. The thesis deals with the investigation of the pyrolysis potential using numerical as well as experimental methods. Furthermore, the negative effect of already low amounts of unsaturated hydrocarbons on a catalyst is shown by using Temperature-Programmed-Methanation and Raman spectroscopy. Finally, actions for avoiding the production of carbon containing deposits are derived from the results.

Numerical simulations have proven itself as a significant and powerful tool for accurate prediction of turbulent premixed flames in practical engineering devices. The work presented in this thesis concerns the development of simulation techniques for premixed turbulent combustion of three different fuels, namely, CNG, LPG and Hydrogen air mixtures. The numerical results are validated against published experimental data from the newly built Sydney combustion chamber. In this work a newly developed Large Eddy Simulation (LES) CFD model is applied to the new Sydney combustion chamber of size 50 x 50 x 250 mm (0.625 litre volume). Turbulence is generated in the chamber by introducing series of baffle plates and a solid square obstacle at various axial locations. These baffles can be added or removed from the chamber to adapt various experimental configurations for studies. This is essential to understand the flame behaviour and the structure. The LES numerical simulations are conducted using the Smagorinsky eddy viscosity model with standard dynamic procedures for sub-grid scale turbulence. Combustion is modelled by using a newly developed dynamic flame surface density (DFSD) model based on the flamelet assumption. Various numerical tests are carried out to establish the confidence in the LES based combustion modelling technique. A detailed analysis has been carried out to determine the regimes of combustion at different stages of flame propagation inside the chamber. The predictions using the DFSD combustion model are evaluated and validated against experimental measurements for various flow configurations. In addition, the in-house code capability is extended by implementing the Lewis number effects. The LES predictions are identified to be in a very good agreement with the experimental measurements for cases with high turbulence levels. However, some disagreement were observed with the quasi-laminar case. In addition a data analysis for experimental data, regarding the overpressure, flame position and the flame speed is carried out for the high and low turbulence cases. Moreover, an image processing procedure is used to extract the flame rate of stretch from both the experimental and numerical flame images that are used as a further method to validate the numerical results. For the grids under investigation, it is concluded that the employed grid is independent of the filter width and grid resolution. The applicability of the DFSD model using grid-independent results for turbulent premixed propagating flames was examined by validating the generated pressure and other flame characteristics, such as flame position and speed against experimental data. This study concludes that the predictions using DFSD model provide reasonably good results. It is found that LES predictions were slightly improved in predicting overpressure, flame position and speed by incorporating the Lewis number effect in the model. Also, the investigation demonstrates the effects of placing multiple obstacles at various locations in the path of the turbulent propagating premixed flames. It is concluded that the pressure generated in any individual configuration is directly proportional to the number of baffles plates. The flame position and speed are clearly dependent on the number of obstacles used and their blockage ratio. The flame stretch extracted from both the experimental and numerical images shows that hydrogen has the highest stretch values over CNG and LPG. Finally, the regime of combustion identified for the three fuels in the present combustion chamber is found to lie within the thin reaction zone. This finding supports the use of the laminar flamelet modelling concept that has been in use for the modelling of turbulent premixed flames in practical applications.

O setor de Gás Liquefeito de Petróleo (GLP), produto considerado de primeira necessidade para a população brasileira, está inserido em um ambiente altamente competitivo devido a poucas barreiras de entrada, ao aumento da atratividade e à baixa diferenciação do produto. Nesse cenário, os sistemas de distribuição propiciam um componente de grande importância no que se refere à diferenciação e ao desenvolvimento de vantagens competitivas no varejo. Assim, o presente estudo tem como objetivo geral analisar os principais aspectos a serem levados em consideração na tomada de decisão sobre os canais de distribuição no segmento domiciliar de GLP, referente ao primeiro elo da cadeia (distribuidora para revenda de GLP). Como objetivos específicos, se destacam a verificação da relevância das variáveis encontradas na literatura para o mercado domiciliar de GLP e a verificação de uma tendência para o setor. Para isso, serão abordados referenciais teóricos sob a ótica da Organização Industrial (OI), da Nova Economia Institucional (NEI) e de Canais de Marketing. Buscando atingir os objetivos propostos, além da revisão teórica, foi realizado um levantamento histórico sobre o GLP e as principais distribuidoras brasileiras, o qual trouxe à tona fatos políticos e econômicos que influenciam até hoje as decisões dos agentes econômicos do setor. O método utilizado foi uma pesquisa qualitativa, por meio de um estudo de caso na maior empresa brasileira de distribuição de GLP, a Cia. Ultragaz S/A. Foram desenvolvidos e aplicados questionários semiestruturados, por meio de entrevistas com os executivos da alta direção da empresa e com um executivo da direção do Sindicato Nacional das Empresas Distribuidoras do Gás Liquefeito do Petróleo (SINDIGÁS), trazendo assim uma visão mais global do segmento. Após a aplicação do estudo de caso, foram encontrados resultados relevantes para a academia, dos quais pode ser citada a constatação de que não existe uma relação direta entre as variáreis \"ativos específicos\" e \"incerteza interna/comportamental\" com a escolha dos canais de distribuição. Outros resultados importantes provindos da análise dos dados foram: a ordenação dos fatores que determinam a escolha dos canais indiretos e a influência das relações de poder na tomada de decisão em canais de distribuição. Por fim, analisando a tendência do setor, o mercado de GLP não deve findar nos próximos 50 anos e, se isso ocorresse, as empresas atuais buscariam novos mercados fora do setor de energia. Dessa forma, apesar das limitações, as quais serão apresentadas ao final da presente dissertação, muitos estudos acadêmicos ainda podem ser desenvolvidos dentro desse setor de expressiva relevância econômica e social para o País. / The Liquefied Petroleum Gas (LPG) sector, a product deemed basic needs for the Brazilian population is placed in a highly competitive environment due to a few barriers to entry, the increase in attractiveness and low product differentiation. In this scenario, the distribution systems provide a component of great importance regarding differentiation and development of competitive advantages in the retail market. Thus, this study aims to conduct an analysis on the main aspects to be taken into consideration when deciding on the distribution channels in the LPG household segment, referring to the first link in the chain (LPG distributor for dealer). The specific objectives are: verifying the relevance of the variables found in the literature for the LPG residential market and verifying the trend for the sector. For this purpose theoretical perspectives will be discussed using Industrial Organization, New Institutional Economics and Marketing Channels. In order to reach the proposed aims, a survey was conducted on the LPG history and major Brazilian distributors besides the theoretical review, which brought up political and economic facts that influence present decisions of economic agents in the industry. The method used was a qualitative research by means of a case study in the largest Brazilian LPG distributor, Cia. Ultragaz S/A. Semi-structured questionnaires were developed and applied by means of interviews with executives from company top management and with an executive director of the National Association of Liquefied Petroleum Gas Distributors (SINDIGÁS), bringing out a global view of the segment. After the application of the case study, relevant results were found to the academy, which may be due to the fact that there is not a direct relationship between the variables \"specific assets\" and \"internal behavioral/uncertainty\" with the choice of the distribution channels. Other important results obtained from the data analysis were: the hierarchical ordering of factors that determine the choice of indirect channels and the influence of power relations in decision making on distribution channels. Finally, by analyzing the industry´s trends, the LPG market should not end in the next 50 years and, if it that happened, current companies would look for new markets outside the energy sector. Thus, despite the limitations, which will be presented at the end of this study, many academic studies can still be developed in a sector which presents economic and social relevancy for the country.

O presente trabalho objetiva identificar e analisar as dimensões de excelência logística, desenvolvidas como forma de se obter vantagens competitivas, buscando analisar a influência do trabalho organizado em equipes na excelência logística de uma organização do mercado de Gás Liquefeito de Petróleo. O trabalho foi realizado através de uma revisão bibliográfica sobre os temas excelência logística nas organizações e trabalho organizado em equipes. Como metodologia foi proposto um construto teórico de excelência logística e trabalho em equipe, realizado através de uma revisão bibliográfica sobre os temas, com a apresentação de um estudo de caso em uma empresa líder do mercado em que atua, de forma a ilustrar a aplicação dos conceitos propostos. Como resultado, o trabalho conclui que a organização do trabalho em equipes se mostra grande apoiadora das práticas de excelência logística nessa organização, integrando e possibilitando o desenvolvimento das diferentes dimensões de excelência logística. / This paper aims to identify and analyze the dimensions of logistics excellence, developed as a way to gain competitive advantage, seeking to analyze the influence of teamwork in the logistics excellence of a Liquefied Petroleum Gas organization. The study was conducted through a literature review on the issues logistics excellence in organizations and teamwork. The methodology has been proposed a theoretical construct of logistics excellence and teamwork, accomplished through a literature review on the issues, with the presentation of a case study in a leading company in the market it operates, in order to illustrate the application of concepts proposed. As a result, the paper concludes that the organization of teamwork is a strong supporter of logistics best practices in this organization, integrating and enabling the development of the different dimensions of logistics excellence.

The Government of India has an ambitious mission of ¡¥power for all by 2012¡¦. This mission would require that the installed generation capacity should be at least 200,000 MW by 2012 from the present level of 114,000 MW. To be able to deliver this power to the entire nation, an expansion of the regional transmission grid-network and inter regional capacity to transmit power would be essential. The latter is required because resources are unevenly distributed in the country and power needs to be transmitted through great distances to areas where load centres exist. Indian government¡¦s ambitious plan can be met. Power generation is one thing but distribution and last mile delivery is a real challenge in remote rural India. 70% of India still lives in such rural settings. India is also notorious for loss of power in distribution due to its out dated distribution infrastructure and mismanagement. A lot is being done to improve the situation however to fast remedy the problem; government and private players can play an important role in setting up small power plants that are based on eco-friendly and efficient mode of power generation. India¡¦s western states and North eastern states are rich in natural gas. Unfortunately these areas are also remote, especially the North Eastern sector. Delivering power is quite a challenge. In search for a solution to this challenge we could be wise to choose greener solutions than otherwise. In the quest of which solution would be suitable for the chosen project, one could look across an array of available conventional and non-conventional sources of energy. Utilizing the locally available natural gas would be a right strategy. It also suits as a green choice. To exploit the availability of natural gas we would need technologies that are of right scale and are easily executable. A multi-million dollar mega gas power generation plant is neither plausible nor executable in those rural settings; however something of a smaller scale could be a good fit. There we see an opportunity for a green technology that may work wonder. Taiwan based Green Power Engineering Corporation has a solution in the form of their cutting edge gas turbine generator. With ease of setup and efficiency coupled with eco-friendly technology, the Gas turbine generators has the potential to be the solution to the much needed rural development by providing them continuous power.

Mit der Dissertation wird eine Periodisierung der Landwirtschaft der SBZ/DDR von 1945 bis 1990 vorgestellt und der LPG-Entwicklung speziell von 1960 bis 1969 vorgenommen. Dabei werden Etappen und Phasen abhängig von Zäsuren unterschieden. Es wird der Weg der drei LPG-Typen von der anfangs z. T. noch großbäuerlichen Wirtschaftsweise bis zur „sozialistischen Kooperation“ aufgezeigt. Dabei kam es zu Formen der Konzentration und Spezialisierung der Produktion. In der Dissertation wird auf sächsische Besonderheiten und Abweichungen von der Staatspolitik eingegangen. Bei der Darstellung der Ergebnisse der LPG werden Vergleiche zwischen den sächsischen Bezirken und der DDR gezogen. Die Arbeit enthält umfangreiche Ausführungen zu den beiden Wegen zur Betriebsvergrößerung der LPG. Als wichtig wurde angesehen, die Entwicklung aller drei LPG-Typen herauszuarbeiten. Die LPG als „sozialistische“ Genossenschaften werden als nicht identisch mit dem deutschen Genossenschaftsgesetz und auf dem „Leninschen Genossenschaftsplan“ fußend charakterisiert. Die Arbeit geht auf „sozialistische Experimente“ in der Agrarpolitik der DDR ein. Der Untersuchungszeitraum für das LPG-Modell in Sachsen fällt mit dem Ergebnis der gescheiterten Wirtschaftsreform der DDR, des NÖSPL, zusammen. Das LPG-Modell, auch in den sächsischen Bezirken, zwischen 1960 und 1970 war der westdeutschen Landwirtschaft hinsichtlich der Versorgungssicherheit nicht überlegen.

Thesis (doctoral)--Göteborgs universitet, 2001. / Extra t.p. with thesis statement inserted. Includes bibliographical references.