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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.
721

Environmental Management Accounting for an Australian Cogeneration Company

Niap, Damian Tien Foo, e58018@ems.rmit.edu.au January 2007 (has links)
This research explores whether Environmental Management Accounting can be applied to assist an Australian cogeneration company in improving both its financial performance as well as its environmental performance. Cogeneration or 'combined heat and power', in this particular case, involves the simultaneous production of heat and electricity using a single fuel, that is, natural gas. The heat generated is then used to produce steam to meet the customers' requirements as well as boost the production of electricity. Therefore, cogeneration provides greater efficiencies compared to traditional electricity generation methods because it utilizes heat that would otherwise be wasted. In addition, greenhouse gases emissions can be reduced substantially. The approach taken in this research is to assess whether an improvement in the energy efficiency of the cogeneration plant can lead to a reduction in greenhouse gases emissions. An improvement in energy efficiency means that either: • less gas is consumed, thus leading to cost savings; or • more electricity is generated for the same quantity of gas consumed, which leads to an increase in income and consequently profit. Therefore, an improvement in energy efficiency means an improvement in the financial performance. In addition, a reduction in the quantity of gas consumed or generating as much electricity as possible from a given quantity of gas can lead to a reduction in greenhouse gases emissions which means an improvement in the company's environmental performance. A case study method, which involves an Australian cogeneration company, is adopted because this would provide valuable in-depth practical insight into the operations and mechanisms of a company that is involved in combined heat and power generation. A review of the literature and the evidence collected indicated that a cogeneration plant's efficiency can be improved at least back to near the plant's designed efficiency. And, further improvements may be achieved by utilizing the latest technology although this involves capital investment. It is also established that an improvement in plant efficiency can reduce greenhouse gases emissions. This research then concludes that Environmental Management Accounting can help the case study company improve its financial and environmental performances. An Environmental Management Accounting system can provide the physical information that is not available in the existing management accounting system. Physical information such as the physical quantities of gas consumed, electricity and steam produced, and greenhouse gases emitted, can help the company in decision-making relating to improving plant efficiency as well as reducing greenhouse gases emissions.
722

Gas phase x-ray photoelectron spectroscopy of some ketone compounds

Situmeang, Rudy T. M. 03 August 1994 (has links)
The photoelectron spectra of a series of ketone compounds have been investigated in the gas phase. Core ionization energies were measured to probe the effects of molecular size and connectivity number on core ionization energies. It was found that core ionization energies roughly decrease with increasing connectivity number as expected. However, subdividing into several categories based on the molecular type gives improved correlations. These results show both the effect of molecular size and that of bringing the polarizable group closer to the core ionized center. In some cases, compounds with the same connectivity number have different core ionization energies and, in others, compounds with different connectivity number have the same core ionization energies. These discrepancies indicate that the simple method for calculating connectivity numbers must be modified to reflect different molecular types. Other discrepancies indicate that this method does not correctly predict the effects of remote hydrogens or the effects of aromatic substituents, where conjugation may influence the relaxation energy. / Graduation date: 1995
723

A study of a novel membrane-based liquid-gas contactor /

Wang, Shunyu, January 2005 (has links)
Thesis (M.Eng.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 92-93.
724

Polarization spectroscopy and photodissociation studies of nitroaromatic compounds in the gas phase /

Abbott, James E. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.
725

Análisis de la contaminación y uso de combustibles sin plomo

Flores Sillerico, Edwin Romelio January 2008 (has links)
El presente trabajo es el análisis de la contaminación en nuestro medio, en el cual solamente tomaremos en cuenta la parte vehicular y no la parte de las industrias, fabricas, chaqueos etc. ya que si fuera así, el análisis tendría que ser mucho mas profundo y a la vez extenso aunque es ya es de conocimiento, que el parque automotor es el que mas contribuye en el deterioro ambiental, empezaremos a partir de los datos recolectados en gestiones ambientales como la semana del el aire limpio a partir del año 2005 hasta el presente 2008. Si bien es cierto que el tema de la contaminación no tiene mucha importancia para los conductores de vehículos públicos (transporte publico) ya que estos son asalariados y con percibir un salario diario quedan satisfechos sin ni siquiera interesarles el estado de el vehiculo con el que trabajan, pero no generalizando los que son propietarios y a la vez conductores de sus propios vehículos son los que mas tienen cuidado de su herramienta de trabajo y hacen lo necesario para mantenerlo en buenas condiciones de funcionamiento, pero sin tomar en cuenta el cuidado del medio ambiente. Son muy pocos los propietarios de vehículos los que tienen un conocimiento apropiado sobre el tema, entre ellos los propietarios de vehículos particulares, pero son muy pocos los que conocen normas, reglamentaciones, programas, respecto al tema de cuidado ambiental. Si bien para el análisis de la contaminación ambiental en nuestro medio, tomamos en cuenta referencias sobre lo que es la contaminación y su impacto ambiental a nivel mundial, se lo hace para realizar una comparación de la dimensión, las consecuencias, las causas para luego plantear soluciones a partir de los datos tomados en nuestra ciudad.
726

The characterization and simplex optimization of a variable-diameter, multielectrode, direct current plasma for atomic emission spectroscopy

McGuire, Joseph 03 March 1989 (has links)
Graduation date: 1990
727

Methane emissions from typical manure management systems

Steed, John Arthur 09 September 1993 (has links)
Methane is the most abundant organic chemical in the earth's atmosphere. Its abundance in the atmosphere is increasing with time and has reached levels not seen in recent geological history. The methane is produced both naturally, and anthropogenically. One of the sources of anthropogenic methane is manure from domesticated animals. Casada and Safley (1990) estimated the amount of methane generated from this source. This was done by estimating the Methane Conversion Factor (MCF) typically achieved by various waste management systems. This study was done to evaluate those estimates of the MCF. The MCF's for the most dominant of disposal methods, rangeland/pasture disposal, were much lower than the earlier estimates. Other waste management systems, such as solid storage and liquid slurry storage had much higher MCF's, at 20° and 30° C. However, these waste management methods are more prevalent in parts of the world where the average annual temperature is closer to 10° C. At that temperature, the MCF is negligible in all waste management systems. This study showed that the previously reported estimates of MCF for some waste management systems were higher than what was actually the case. Consequently earlier estimates of the amount of methane generated from manures were higher than what this study found. / Graduation date: 1994
728

Sampling-Window Based Approach for Fire Gas Analysis of Rigid Foams

Jones, Bryn January 2013 (has links)
A sampling-window based approach was developed to collect and analyze the gases evolved during fire performance testing using the cone calorimeter. For this purpose, a Fourier Transform Intra-red (FTIR) Spectroscopy system and a Novatec analyzer were coupled to the cone calorimeter. An experimental gas sampling apparatus was designed and constructed and a sampling-window based method was developed. The sampling-window based method was initially tested using blue Styrofoam samples, then a small number of intumescent materials were also examined. Using the new integrated system, spectral scans were taken with an FTIR using 30s, 45s and 60s sampling windows, during off-gasing, fire growth, steady heat release rate, and fire decay stages of cone calorimeter testing. By focusing the sampling window on a specific stage of fire development the tests indicated that high concentrations of toxic gases were evolved during sample off-gasing, before ignition. In contrast to other methods that are designed to obtain total toxic gas yield over the full course of a cone calorimeter fire performance test, the sampling-window method here allows for a greater understanding of fire gas evolution at the various stages of fire growth and development. With the cone calorimeter coupled with a preconfigured “out of the box” lightweight portable ambient air analyzer and the sampling-window based approach developed, the fire gases associated with the polystyrene (blue Styrofoam) could be identified along with a number of the fire gases typically associated with the intumescent foam. For further analysis of fire gases produced, a calibrated, lab quality FTIR, with a higher resolution than the preconfigured “out of the box” lightweight portable ambient air analyzer may be required. However the system configuration and methodology would remain the same as developed here. The sampling-window based approach developed is useful for use in the development of other gas sampling techniques and can be used with other complimentary techniques such as Gas Chromatography (GC) and Mass Spectroscopy (MS). In such a combined Cone Calorimeter-GC-MS system, the GC is used to separate the various fire gases while the MS is used to identify all the components at a molecular level, and provide a more concise analysis of evolved fire gases. It is therefore recommended that the GC-MS technique also be developed for the cone calorimeter and used to compliment the FTIR technique developed in this study.
729

Desarrollo de microestructuras de vidrio/silicio para la fabricación de sensores de gases con circuitería CMOS asociada

López Bosque, María Jesús 19 February 2004 (has links)
El objetivo de esta tesis es el diseño y fabricación de una estructura de vidrio/silicio que permita la integración en un mismo chip de una matriz de sensores de gases y circuitería CMOS. Estas estructuras deben poseer una elevada robustez, alta temperatura de trabajo con un bajo consumo. La estructura está formada por una plataforma a alta temperatura aislada térmicamente (donde se integrará la matriz de sensores de gases) y la parte CMOS. En las plataformas de silicio micromecanizadas se integra una matriz de cuatro sensores de gases trabajando a la misma temperatura. Este tipo de configuración es interesante en aplicaciones donde diferentes materiales se depositan en la misma plataforma para mejorar la selectividad de los sensores a una concentración de gases. La electrónica incluye un bloque de control de temperatura en el área activa y un bloque de lectura de las señales de los sensores.Los principales puntos que se tratan en la tesis son: - Descripción de las estructuras de vidrio/silicio para la fabricación de un sensor de gases integrado monolíticamente con circuitería CMOS - Diseño y simulación: se han realizado una serie de simulaciones numéricas preliminares con el método de los elementos finitos (FEM) para optimizar el aislamiento térmico de las plataformas de silicio en función de la geometría del dispositivo, y de ese modo reducir el consumo de la estructura. - Análisis de la compatibilidad de la tecnología CMOS y de sensores de gases- Fabricación de los dispositivos:a. Micromecanizado del vidriob. Soldadura anódica vidrio/silicioc. Proceso de fabricación CMOS añadiendo los pasos y materiales necesarios para la incorporación de los elementos propios de sensores de gasesd. Deposito de materiales sensibles a gases Caracterización de los dispositivos: mecánica, térmica y eléctrica de la matriz de sensores de gases para analizar la fiabilidad de las estructuras. / The aim of the work is the design and fabrication of glass/silicon structure that allows to the on-chip integration of CMOS electronics and gas sensor array with high robustness, high operation temperatures and low power consumption. The structure is composed of a glass/silicon thermally isolated µ-hotplate, on which a sensor array is integrated, and a CMOS electronics part. Arrays of four semiconductor gas sensors (SnO2-based) working at the same temperature were placed on micromachined silicon platforms. These array configurations are of interest for applications on which different sensing materials are deposited on the same platform to improve the selectivity to a given set of gases. The electronics includes the necessary for accurate control of temperature and for resistive-based gas sensor transduction.The main points of this works are:- Description of glass/silicon structures for the fabrication of a CMOS monolithically integrated gas sensor array with electronics - Design and simulation: Preliminary numerical simulations made with the Finite Element Method (FEM) have been done in order to optimise the thermal isolation of the silicon platform and so to reduce the power consumption as a function of the geometry of the device.- Semiconductor gas sensor compatibility with CMOS technologiesFabricationa. Glass structuring technology b. Anodic bonding of thin glass columnsc. CMOS process fabrication with special materials and non-CMOS standard processing and post-processing sequencesd. Gas sensitive material deposition and patterning.Characterisation: Mechanical, thermal and electrical characterisation of the gas sensor arrays have been done for demonstrating the feasibility of the structure.
730

Efecto del templado sobre la permeación de gases a través de filmes de polietileno lineal de baja densidad obtenidos por coextrusión

Andrio Balado, Andreu 10 July 1998 (has links)
En esta tesis se han estudiado las propiedades difusivas de tres filmes de polietileno lineal de baja densidad a los gases nitrógeno, oxígeno y dióxido de carbono. Se ha medido los coeficientes de permeabilidad, difusión y solubilidad aparentes en función de la temperatura, la presión y el tiempo de templado. La evolución de los resultados con el cambio de presión ha sido interpretada utilizando el modelo dual de sorción, así mismo, la evolución con la temperatura ha sido interpretada en términos del modelo de volumen libre desarrollado por Fujita y modificado por nosotros para polímeros semicristalinos. Finalmente se ha llevado a cabo un estudio de la permselectividad de estos filmes los citados gases también en función de la temperatura, presión y tiempo de templado.

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