published_or_final_version / abstract / toc / Speech and Hearing Sciences / Master / Master of Science in Audiology

published_or_final_version / abstract / toc / Speech and Hearing Sciences / Master / Master of Science in Audiology

published_or_final_version / abstract / toc / Speech and Hearing Sciences / Master / Master of Science in Audiology

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No description available.

The present work deals with the calculation and the investigation of possible reductions of CO2 emissions in manufacturing a metal formed product. The industrial sector plays a significant role in the recent increase of the oncentration of Greenhouse Gases in the atmosphere, which is responsible for the advancing global warming. As an answer to fiscal and financial intervention of government policies aimed at counteracting this phenomenon, the environmental impact of products became a key aspect of a company’s strategy. However, literature still lacks effective methods and quantitative studies that look into the details of a single manufacturing process, discussing its environmental aspects and how they can be influenced by changes in the technological parameters. In an attempt to do that, an example of quantification and minimization of the carbon emissions occurring during the two manufacturing steps of the fabrication of an Al 6061 disc is provided. Electrical energy consumption occurring during the shearing and the upset forging of a billet was found by means of nonlinear finite element analysis and converted into CO2 emissions with a carbon emission signature value (CES). Environmental impact and frictional properties of both traditional lubrication and two non-conventional ecologically benign lubricants (palm oil ester and used cooking oil ester) were experimentally tested and are included in the study. A gradient-based optimization algorithm was implemented to determine the optimal geometry of the billet before the compression as well as the lubricant that minimize the total carbon emissions, within the proper technological limitations and constraints on the final product quality. A clear and effective method which would represent an auxiliary decision tool for a manufacturer in the metal forming sector is hereby presented. Results show that the selection of the manufacturing options can have an influence of more than 13% on the overall CO2 emission. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-12-19 16:39:12.071

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In occupational and public health there is a need for measurement and speciation of chemicals in ambient air to achieve control of air pollution and minimize health risks. In this work two methods of analysis are developed for the analysis of polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) under ambient air conditions. Both methods involve the use of thermal desorption techniques with gas chromatography-mass spectrometry (GC-MS). For the measurement of polycyclic aromatic hydrocarbons (PAHs) airborne particulate samples are obtained by collection on small glass fibre filters. The volatile materials from these are thermally desorbed in two stages and transferred to a Gas Chromatograph-Mass Spectrometer analytical system. Results from studies of particulate samples obtained from sites in the region of Uxbridge, Middlesex are reported for eight selected polycyclic aromatic hydrocarbons (PAHs). Measurements on samples obtained directly from vehicle emission sources with the engine used under different running conditions are also reported. In the method of analysis of volatile organic compounds in air, samples are absorbed into 4mm Carbotrap 300 tubes and thermally desorbed and passed into a gas chromatography-mass spectrometry (GC/MS) or gas chromatography (GC) using helium as carrier gas. The Carbotrap absorbers used, show complete absorb/desorb reversibility, are thermally stable and do not react chemically with injected hydrocarbon standards. To demonstrate the value of the method analytical results obtained under ambient air conditions on the Brunel University campus (Uxbridge, Middlesex) are reported. Six selected low molecular weight aromatic hydrocarbons namely benzene, toluene, ethyl benzene and m-, p- and o-xylene are investigated in detail. The concentrations of these compounds were measured and results related to traffic flow rates and meteorological conditions to establish the fact that vehicle exhaust emissions are the main sources of the volatile organic compounds (VOCs) pollution at the collection sites. A study of volatile organic compounds (VOCs) levels in ambient air in Tehran (Iran) in which 55 hydrocarbons are identified is reported. A detailed study is made of the concentrations of the six hydrocarbons benzene, toluene, ethyl benzene and m-, p- and o-xylene because high concentrations of these pollutants can produce potential health problems. It is shown that the nature of the geographical location and the day time temperature play an important part in determining the composition of the mixture of pollutants in Tehran. Samples obtained directly from internal combustion engines with and without catalytic converters are also analysed using the method developed and the results show that there is a large depletion in aromatic hydrocarbons when toluene is reduced to a greater extent than benzene. The analytical method is also used to compare vehicle emissions from engines under cold start and hot start conditions.

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