Examensarbete.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "August, 2007." Includes foldout illustrations. Includes bibliographical references (leaves 79-84). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

Made available in DSpace on 2014-10-09T12:35:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:40Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Thesis (MDiploma (Mechanical Engineering))--Cape Technikon, 1992. / An investigation into the use of thermoelectric cooling energised by photovoltaic (PV) panels for removing sensible heat from electronic telecommunications equipment. The thermoelectric cooler consists of a solid-state heat pump which operates on the principle of the Peltier effect. The thermoelectric device transfers heat through a cold sink to ambient outside air via a hot sink. A major prerequisite was that the system should be selfsufficient in terms of power because the sites for the microwave transmitters are often remote. Solar power was the only alternative source of energy and the cooler was designed to accept direct current from PV panels which are usually used to power transmitters on distant locations. The cooling device had to be reliable, virtually maintenance-free and simple to repair.

Made available in DSpace on 2014-10-09T12:35:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:40Z (GMT). No. of bitstreams: 0 / A perfilagem de colunas por raios gama (column gamma scan) é uma técnica nuclear empregada para solucionar problemas em equipamentos de processos industriais, nas refinarias e petroquímicas. Consiste na utilização de uma fonte selada e um detector de radiação [NaI(Tl)], obtendo-se o perfil de densidade unidimensional (1D) do equipamento. Nas últimas décadas, ocorreram algumas melhorias na técnica de perfilagem, tais como, na digitalização contínua das informações e nos sistemas de detecção da radiação (wireless). Novos aplicativos melhoraram a qualidade da apresentação dos resultados. Entretanto, a condição da técnica não mudou drasticamente, desde sua criação. Seu resultado é simplesmente um gráfico 1D da densidade média, em função da altura do equipamento industrial. A tecnologia inovadora proposta neste trabalho de Mestrado utiliza a reconstrução tomográfica industrial, via algoritmos iterativos derivados da ART (Algebraic Reconstruction Technique) e do MART (Multiplicative Algebraic Reconstruction Technique), para apresentar o resultado de perfilagem como uma imagem bidimensional (2D) da distribuição de densidade, ao invés de um gráfico 1D. Nitidamente, uma imagem 2D possui mais informações técnicas do equipamento em análise, permitindo um avanço na tecnologia de ensaios não destrutivos (END). Assim, muitos problemas operacionais não detectáveis em equipamentos de processos industriais podem ser descobertos e solucionados de forma on-line, usando-se o imageamento 2D. Esta tecnologia permitiu que um pedido de patente fosse depositado junto ao Instituto Nacional de Propriedade Industrial (INPI). / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

From observations of the field and laboratory operations, several ideas as to improvement of the construction and operation of the pasteurizer were conceived. / Master of Science

Laboratory-obtained, manufacturer-supplied hearing protector attenuation ratings typically overestimate the workers' protection level In the workplace. In addition, several work-related in-field factors often degrade protection performance of the hearing protection devices (HPDs), posing the threat of underprotection for industrial workers. This research investigated the effects of HPD wearing time, subject activity movement, and HPD fitting procedure on the frequency-specific attenuation and user-rated comfort achieved with a popular foam cushion earmuff, two types of earplugs (user-molded foam and pre-molded, triple-flanged polymer), and an earmuff over foam earplug combination. Both attenuation and comfort data were collected from 40 naive but audiometrically normal subjects. Using a psychophysical real-ear-attenuation-at-threshoId-measurement procedure, attenuation data were obtained before, during, and after the activity movement tasks, which induced typical worker movements, so that the influence of wearing time and activity movement could be determined. Bipolar comfort rating data were also collected before and after the activity movement tasks, The results of statistical analyses indicated that achieved attenuation and user comfort significantly decreased over a two-hour wearing period and that training to achieve better fitting markedly improved protection, although these changes were device- and frequency-specific. Loss in frequency-specific attenuation over the wearing period was up to 6.3 dB for all HPDs except the foam plug, and attenuation Improvement due to training ranged from 4 to 14 dB for all HPDs except the earmuff at 1000 Hz and below. Almost no difference In achieved attenuation or comfort was found between the two activity (head/torso and temporomandibular) movements, but the earmuff tended to slip during highly kinematic head/torso movement. In general, out of the four different HPD configurations used in the study, the foam plug was very resilient to either type of activity movement but did benefit more than the other devices from the training for proper tilting; it was also perceived as the most acceptable and stable HPD by the subjects. In summary, the research illuminated the strong influence of in-field factors on HPD effectiveness. / Master of Science

Hearing protection devices (HPDs), a widely used countermeasure against noise-induced hearing loss, are laboratory-tested for their attenuation (noise reduction) capabilities. Unfortunately, laboratory tests overestimate the in-workplace performance of the devices, potentially leading to inadequate protection for the user. Many factors affect in-field effectiveness, including the physical design and "wearability" of the protector. Wearability, a highly subjective aspect which encompasses such characteristics as user comfort, ease of use, and acceptability, directly affects performance by influencing the regularity of use and the manner in which a protector is worn. This research investigated the influence of the user's work-related activities over a prolonged wearing period, and of variations in headband compression force and cushion material (liquid- or foam-filled) on achieved noise attenuation and wearability (comfort and acceptability) of earmuff hearing protectors. REAT (real-ear attenuation at threshold) testing procedures were used to collect attenuation data on 24 subjects, both prior-to and following completion of a simulated work task. Bipolar rating scales were utilized to collect pre- and post-task wearabi1ity data. Statistical analyses demonstrated that the work-related movement and wearing time significantly reduced achieved attenuation and, for higher compression earmuffs, also degraded perceived comfort and acceptability. A high headband compression force was 1inked to increased attenuation and to poorer user comfort and acceptance. The data revealed no significant difference in achieved attenuation or wearability between cushion types. The results illustrate the powerful influence of physical activity on HPD effectiveness and the criticality of certain earmuff design parameters to both attenuation and wearability. Furthermore, the existing tradeoff in earmuff design between comfort and attenuation was clearly demonstrated. / Master of Science

Abstract not available

M. Tech. Chemical Engineering. / Discusses the HybridICE filter as a new but economical device for separating the ice from the slurry in freeze desalination processes. There is no direct information in the literature on the filter so there is a need to describe the principles behind the operation. There is also a need to investigate the filtering process in order to increase yield and purity of the ice produced. No design method exists for the filter. A design method has to be established so that when the required flow-rate is determined, the dimensions of the filter can be calculated.