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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.
1

Life cycle energy demand and greenhouse gas emissions in China's road transport sector : future trends and policy implications

Yan, Xiaoyu January 2008 (has links)
A critical evaluation of the national profile of energy supply and demand and the associated greenhouse gas (OHO) emissions in China has been conducted. The contribution of the transport sector in China, the road transport sector in particular, to China's overall energy demand and OHO emissions has been assessed and compared with values for other countries. Approaches for reducing energy demand and OHO emissions in the road transport sector worldwide have been reviewed. A detailed bottom-up model has been developed using 'LEAP' software, to estimate future energy demand and OHO emissions in China's road transport sector, incorporating China's recent efforts in alternative fuel promotion. Modelling approach and historical data used have been tested and verified to ensure reliability. Two scenarios have been designed to describe the future strategies relating to the development of China's road transport sector between 2005 and 2030. The 'Business as Usual' scenario is used as a baseline reference scenario, in which the government is assumed to do nothing to influence the long-term trends of road transport energy demand. The 'Best Case' scenario is considered to be the most optimized case where a series of available reduction measures are assumed to be implemented. Energy demand and OHO emissions in China's road transport sector up to 2030 are estimated in these two scenarios. The reduction potential and the relative contribution of each measure have been estimated. A 'life cycle assessment' model for the road transport sector has been developed. The life cycle energy demand and OHO emissions in China's road transport sector are estimated using the model. The reduction potential and the relative contribution of each measure have been re-assessed from a life cycle perspective. Potential impacts on global oil resources, availability and prices are discussed. The importance of life cycle assessment in evaluating the effects of different reduction measures is discussed. Policy implications are presented.
2

La Regulación del Representante de los Obligacionistas en el Ámbito del Mercado de Valores

Torres García, Farah 10 April 2018 (has links)
En el presente artículo, la autora hace una introducción a la figura del Representante de los Obligacionistas detallando los requisitos, funciones, responsabilidades y demás características de dicha institución, acompañando esto de las normas concernientes a esta figura. Centrándose en la emisión de obligaciones por oferta pública, la autora nos narra estos aspectos necesarios del Representante de los Obligacionistas, pieza clave entre el Sindicato de los Obligacionistas y el emisor.
3

Studium kontaminace říčních sedimentů platinovými kovy / Study of contamination of river sediments with platinum metals

Novotný, Matěj January 2018 (has links)
This work deals with the characteristics of platinum metals and problems related to their toxicity and mobility in the environment, especially in the aquatic environment. These metals are released into the environment due to the use of automotive catalysts. Their function is based on the catalytic properties of platinum metals. Because of the high temperatures, these metals can be oxidized in the catalyst and subsequently emitted together with the combustion products into the surrounding atmosphere. The aim of the thesis is to measure real samples of river sediments of the river Svratka on the territory of the city of Brno and to find the possibility of contamination of the aquatic environment with these metals.
4

[en] ION DESORPTION DESCRIBED BY AN EXTENDED NUCLEAR TRACK MODEL: APPLICATION TO WATER ICE CLUSTERS / [es] EXTENSIÓN DEL MODELO DE TRAZO NUCLEAR PARA DESCRIBIR LA DESORCIÓN IÓNICA: APLICACIÓN A LOS AGLOMERADOS DE HIELO / [pt] EXTENSÃO DO MODELO DE TRAÇO NUCLEAR PARA DESCREVER A DESSORÇÃO IÔNICA: APLICAÇÃO AOS AGREGADOS DE ÁGUA

PETER DARWIN IZA TOAPANTA 18 October 2006 (has links)
[pt] A dessorção de íons secundários induzida por impacto de projéteis velozes é um fenômeno de interesse tanto da pesquisa fundamental dos processos de colisão quanto da Física de Superfícies, Biociência e Astrofísica. O modelo teórico de dessorção iônica induzida por elétrons baseado na formação de um traço nuclear é aprimorado no presente trabalho. Considera-se que o traço seja composto por um infratraço de carga positiva e um ultratraço de carga negativa. Ao chegarem na superfície do sólido, os elétrons secundários emanados do infratraço geram íons que são em seguida acelerados por ação do campo elétrico produzido pelos traços. Os dados experimentais escolhidos para testar o modelo correspondem à dessorção iônica induzida em filmes finos de gelo (H2O) por íons de nitrogênio de 1,7 MeV. As velocidades de emissão e as massas dos íons dessorvidos foram determinadas pela técnica de tempo- de-vôo. Empregou-se um detector de íons composto por um par de placas de microcanais e por um anodo sensível à posição de impacto dos íons. Os dados obtidos pela técnica XY-TOF mostram diferenças de simetrias na distribuição angular dos íons secundários. Em especial, observou-se emissão quase isotrópica dos agregados leves em relação a normal à superfície, contrastando com a dos agregados pesados que apresenta distribuição assimétrica atribuída a um efeito de memória da direção do projétil durante a emissão iônica. Um acordo entre os resultados do modelo e os dados experimentais é considerado razoáve / [en] Secondary ion desorption induced by impact of fast projectiles is an important phenomenon not only because it is directly connected to atomic collision processes in solids, but also to practical implications in the Physics of Surfaces, Bioscience and Astrophysics. A theoretical model describing the desorption induced by secondary electron (SEID) produced in nuclear tracks is extended in the present work. It considers that the nuclear track is composed by a positive charged infratrack and a negative charged ultratrack. Secondary electrons emanated from infratrack reach the surface of the solid and generate molecular ions which are accelerated by an electric field produced by the track. The experimental data obtained by a 1.7 MeV nitrogen beam inducing electronic sputtering on condensed water target are used to test the SEID model. The initial velocity vectors and the masses of the emitted ions were obtained by the time-of-fight technique equipped with a position sensitive delay line detector XY-TOF. The data obtained by the technique show differences of symmetries in the angular distribution of the secondary ions. In particular, isotropic emission was observed for light clusters in relation to normal to the surface, contrasting with heavy clusters that show an asymmetric distribution attributed to nuclear track memory direction during the emission. The agreement between the model results and experimental data is considered reasonable. / [es] La desorción de iones secundarios a partir de la incidencia de proyectiles rápidos en superficies es un fenómeno de gran interés científico en áreas de Física de Colisiones (interacciones ión-sólido), Física de Superficies, Bio-ciencia y Astrofísica. En esta Tesis fue desarrollado un modelo teórico para describir el proceso de desorción iónica inducida por los electrones emitidos durante la formación del trazo nuclear. El modelo considera que el trazo trazo nuclear. Las predicciones del modelo fueron comparadas con las mediciones de las especies emitidas por la incidencia de iones de nitrógeno de 1,7 MeV en películas delgadas de hielo (H2O). Las especies emitidas y sus velocidades iniciales fueron determinadas utilizando la técnica tiempo de vuelo (TOF). Fue utilizado un detector formado por un par de placas de micro canales con un ánodo sensible a la posición de impacto de los iones (técnica XY-TOF). Dos tipos de distribuciones angulares de los iones secundarios fueron observadas: isotrópica para masas pequeñas y anisotrópica para masas grandes. La distribución angular de masas grandes es preferencialmente simétrica a la dirección de incidencia del proyectil con respecto a la normal a la superficie y se debe al efecto de memoria del trazo nuclear sobre la dirección de incidencia del proyectil. Los resultados teóricos y los valores experimentales concuerdan parcialmente.
5

Obsah toxických a esenciálních prvků v biopotravinách a jejich porovnání s běžnými potravinami / Content of toxic and esential elements in bio foodstuffs and their comparing with ordinary foodstuffs

Kohoutková, Nina January 2009 (has links)
The aim of this study is to determine the content of toxic and essentials elements in samples of nuts and seeds produced by ecologic agriculture and to compare results with nuts and seeds from conventional agriculture production. These nuts and seeds can be bought in the Czech market (except bio pine nuts, bio pecan nuts and bio pistachios). The amount of elements was analysed using inductively coupled plasma mass spectrometry after previous digestion of samples using microwaves. This study summarizes the main physiological functions of toxic and essentials elements. Results were also compared with another studies. It does not results from all measured amounts of all essential elements, that bio nuts and seeds have higher amounts of these elements; however, all amounts of toxic elements in bio nuts and seeds are lower than in the no-bio ones. For more precise results it would be necessary to measure more samples.
6

Experimental Characterisation of Real Driving Cycles in Diesel Passenger Vehicles under Different Environmental Conditions

Redondo Puelles, Fernando 01 September 2023 (has links)
[ES] El futuro de los Motores de Combustión Interna en el sector de la automoción parece incierto, en cierta medida, debido a los cambios recientes en las normativas de homologación. Las regulaciones actuales han reducido considerablemente los límites de emisiones contaminantes , así como también han introducido pruebas más exigentes. La introducción de ciclos de conducción reales supuso un reto para los fabricantes de automóviles a la hora de homologar sus vehículos, ya que el tradicional y poco exigente ciclo de certificación del New European Driving Cycle (NEDC) ha sido sustituido por ciclos más severos como el World Light-Duty Test Cycle (WLTC) y Real Driving Emissions (RDE). Este estudio, en primer lugar, presenta una metodología para implementar ciclos RDE en un banco de ensayos de motores. Aun sabiendo que la esencia de la regulación RDE es evaluar las condiciones reales de conducción, reproducir los ciclos RDE en un banco de pruebas es de gran interés ya que las condiciones controladas y reproducibles que se pueden lograr en un laboratorio aportan información valiosa para entender el comportamiento del motor en conducción real, y por lo tanto contribuyen al desarrollo del motor. Este documento aplica la normativa más reciente de la Comunidad Europea y establece los pasos imprescindibles para realizar un ciclo RDE en un banco de pruebas de motores. En segundo lugar, gracias a que se ha demostrado la viabilidad de una sala de pruebas para realizar ciclos RDE, se han realizado diferentes ciclos RDE bajo diferentes solicitaciones dinámicas y condiciones externas como tempera- tura ambiente o temperatura del aire de admisión. Posteriormente, se analizó la emisión de contaminantes y el consumo de combustible con el fin de caracterizar los ciclos y condiciones de RDE. Además, se ha llevado a cabo una comparación de las emisiones y el consumo de combustible de las pruebas RDE frente a las obtenidas en las pruebas de estado estacionario, donde se encontraron discrepancias bastante bajas / [CA] El futur dels Motors de Combustió Interna al sector de l'automoció sembla incert, en certa mesura, a causa dels canvis recents a les normatives d'homologació. Les regulacions actuals han reduït considerablement els límits d'emissions contaminants i també han introduït proves més exigents. La introducció de cicles de conducció reals va suposar un repte per als fabricants d'automòbils a l'hora d'homologar els seus vehicles, ja que el tradicional i poc exigent cicle de certificació del New European Driving Cycle (NEDC) ha estat substituït per cicles més severs com el World Light-Duty Test Cycle (WLTC) i Real Driving Emissions (RDE). Aquest estudi, en primer lloc, presenta una metodologia per implemen- tar cicles RDE a un banc d'assajos de motors. Tot i saber que l'essència de la regulació RDE és avaluar les condicions reals de conducció, reproduir els cicles RDE en un banc de proves és de gran interès ja que les condicions controlades i reproduïbles que es poden aconseguir en un laboratori aporten informació valuosa per entendre el comportament del motor en conducció real, i per tant contribueixen al desenvolupament del motor. Aquest document aplica la normativa més recent de la Comunitat Europea i estableix els passos imprescindibles per fer un cicle RDE en un banc de proves de motors. En segon lloc, gràcies al fet que s'ha demostrat la viabilitat d'una sala de proves per fer cicles RDE, s'han realitzat diferents cicles RDE sota diferents sol·licitacions dinàmiques i condicions externes com ara temperatura ambient o temperatura de l'aire d'admissió. Posteriorment, es va analitzar l'emissió de contaminants i el consum de combustible per tal de caracteritzar els cicles i les condicions de RDE. A més, s'ha dut a terme una comparació de les emissions i el consum de combustible de les proves RDE davant de les obtingudes a les proves d’estat estacionari, on es van trobar discrepàncies força baixes- / [EN] The future of Internal Combustion Engines in the automotive sector seems uncertain, to some extent, due to the recent changes in type approval regulations. Current regulations have considerably reduced the engine pollutant emissions limits, as well as introduced more demanding testing conditions. The introduction of real driving cycles presented a challenging issue for car manufacturers when homologating their vehicles, since the traditional and undemanding New European Driving Cycle (NEDC) certification cycle has been replaced by more severe cycles such as World Light-Duty Test Cycle (WLTC) and Real Driving Emissions (RDE). This study, in the first place, presents a methodology for implementing RDE cycles in an engine test bench. Even knowing that the essence of RDE regulation is to assess actual driving conditions, reproducing RDE cycles in a test bench is of great interest since, the controlled and reproducible conditions that can be achieved in a laboratory lead to valuable information to understand engine behaviour in real driving conditions, and therefore contribute to engine development. This document applies the most recent European Community regulation and sets the essential steps to carry out an RDE cycle in an engine test bench. Secondly, as the feasibility of a test bench to perform RDE cycles has been proven, different RDE cycles have been performed under different dynamic solicitations and external conditions such as ambient or intake air temperatures. After that, the pollutant's emission and fuel mass consumption were analysed with the aim of characterising RDE cycles and conditions. Furthermore, a comparison of RDE test emissions and fuel consumption versus those obtained from steady-state tests has been carried out, where very small discrepancies were found. / Redondo Puelles, F. (2023). Experimental Characterisation of Real Driving Cycles in Diesel Passenger Vehicles under Different Environmental Conditions [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196653

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