Starting in September 1984, the Telesign project is an extensive and complex project proposed and undertaken by Dr. Nadler at Virginia Tech. The emphasis of this project is to enable the members of the deaf community to communicate visually using sign language or lip reading over the telephone network. The Image Processing Board (IPB) is the 'Brain' of the whole system. The IPB processes a given frame of an image to transmit only selected data. It uses the pseudo-laplacian operator, invented by Dr. Nadler, for edge detection. According to a recent survey of various edge detection algorithms by D. E. Pearson, [1], the pseudo-laplacian operator is the most efficient one and it produces the most natural pictures. The whole IPB hosts about one hundred LSI/VLSI chips according to the present hardware description. In the case of such a big system, hardware simulation becomes mandatory in order to ensure reliability of the design and to anticipate any kind of logic or timing errors in the design. This thesis describes the modifications to the original design to make it reconfigurable with proper initialization and the Hardware Simulation of the IPB, using General Simulation Program (GSP), including some comments on the simulators available at Virginia Tech and in particular a critique of the simulator used here. Many improvements to the simulator are suggested. Precautions to be taken while preparing the lay-out and wiring of the IPB, suggestions to simplify the design at some points at the cost of a few more chips, and lastly the instructions to run the models to get the required results, are outlined in this thesis. / Master of Science

Fouling of heat treatment equipment in the dairy processing industry is an expensive and persistent problem. The objective of this work was to develop a better understanding of the mechanisms of dairy fouling in heat exchangers and identify methods to control this build-up. This was part of a larger project investigating the interaction between spore-forming thermophilic bacilli (thermophiles) contamination and fouling deposits on internal surfaces of equipment. Two systems were developed to monitor the onset and build-up of fouling on the internal surfaces of two research heat exchangers. The first used a commercial sensor to measure the local heat flux and the temperature on the hot side of a plate type heat exchanger. The heat transfer coefficient was calculated and normalised with its value at the start of the run to reflect the contribution of fouling deposits to the thermal resistance, thus giving a real-time estimate of the rate of fouling. The second system used an energy balance over a tubular type heat exchanger and measured inlet and outlet temperatures to estimate the overall heat transfer coefficient thus giving a global measurement of fouling over the tubular heat exchanger. In both systems the plot of normalised heat transfer coefficient over time often stayed constant over an induction period, which was followed by a falling period indicative of growth in the fouling layer thickness and/or mass. Each system was validated by comparing the final value of the normalised heat transfer coefficient with direct measurements of fouling made at the end of a run namely: fouling deposit height for the local measurement and fouling deposit mass for the global measurement. The normalised heat transfer coefficient reported by each system correlated well with the corresponding direct measurement of the fouling layer. An important factor identified in this study was the effect of air bubble nucleation on fouling deposits. It was shown that bubbles that formed on the heated surface greatly reduced the length of the induction period to a matter of seconds rather than hours, as found in previous studies of fouling in the absence of surface bubbles. The rate of fouling was also enhanced while the bubbles remained at the surface. The structure of bubble type fouling layers was linked to the behaviour of the bubbles at the heated surface. Visual observations of these bubbles showed evidence of growth, vibration and coalescence during their period of attachment to the heated surface. Deposits from bubble type fouling consisted of all solid components found in the original milk solution, except lactose, in approximately the same ratio. By contrast fouling deposits reported in the literature with systems operating under the traditional protein denaturation mechanism were reported to consist mainly of whey proteins. Bubble induced fouling can be limited in a number of ways, the most effective being to maintain a high operating pressure in the equipment to ensure nucleation does not occur. Experiments conducted in this study showed that a pressure of 130 kPa.g was sufficient to suppress all bubble nucleation at the heated surface at a temperature of 90°C. Another method identified was the use of high linear fluid velocities to entrain any surface bubbles into the processing stream immediately upon nucleation. Linear velocities above 1.0 m/s were shown to achieve this goal in the miniature plate heat exchanger tested. However, this method is only partially successful because the local linear velocity varies with position in heat exchange equipment of complex geometries and can drop below the mainstream average velocity causing surface bubbles to form, especially in recirculation regions behind flow obstacles. A more reliable method, in situations where high operating pressures could not be used, involved conditioning the heated surface with a thin protein layer during the first few minutes of a run. Conditioning the surface resulted in bubble suppression even at high temperatures and low pressures, thus greatly extending the length of the induction period. Trials performed in this study showed that the addition of a proteolytic enzyme produced by psychrotrophic microbes greatly increased fouling. The enzyme destabilised the caseins which could attach directly to the heat exchange surface independently from the bubble fouling mechanism. Thus the quality of the milk is another important factor to consider. However, the addition of enzymes produced by thermophilic bacilli isolated from milk powder plants did not increase fouling. A theory describing the air bubble induced fouling mechanism is presented along with recommendations on how to reduce this fouling contamination in processing equipment.

Fouling of heat treatment equipment in the dairy processing industry is an expensive and persistent problem. The objective of this work was to develop a better understanding of the mechanisms of dairy fouling in heat exchangers and identify methods to control this build-up. This was part of a larger project investigating the interaction between spore-forming thermophilic bacilli (thermophiles) contamination and fouling deposits on internal surfaces of equipment. Two systems were developed to monitor the onset and build-up of fouling on the internal surfaces of two research heat exchangers. The first used a commercial sensor to measure the local heat flux and the temperature on the hot side of a plate type heat exchanger. The heat transfer coefficient was calculated and normalised with its value at the start of the run to reflect the contribution of fouling deposits to the thermal resistance, thus giving a real-time estimate of the rate of fouling. The second system used an energy balance over a tubular type heat exchanger and measured inlet and outlet temperatures to estimate the overall heat transfer coefficient thus giving a global measurement of fouling over the tubular heat exchanger. In both systems the plot of normalised heat transfer coefficient over time often stayed constant over an induction period, which was followed by a falling period indicative of growth in the fouling layer thickness and/or mass. Each system was validated by comparing the final value of the normalised heat transfer coefficient with direct measurements of fouling made at the end of a run namely: fouling deposit height for the local measurement and fouling deposit mass for the global measurement. The normalised heat transfer coefficient reported by each system correlated well with the corresponding direct measurement of the fouling layer. An important factor identified in this study was the effect of air bubble nucleation on fouling deposits. It was shown that bubbles that formed on the heated surface greatly reduced the length of the induction period to a matter of seconds rather than hours, as found in previous studies of fouling in the absence of surface bubbles. The rate of fouling was also enhanced while the bubbles remained at the surface. The structure of bubble type fouling layers was linked to the behaviour of the bubbles at the heated surface. Visual observations of these bubbles showed evidence of growth, vibration and coalescence during their period of attachment to the heated surface. Deposits from bubble type fouling consisted of all solid components found in the original milk solution, except lactose, in approximately the same ratio. By contrast fouling deposits reported in the literature with systems operating under the traditional protein denaturation mechanism were reported to consist mainly of whey proteins. Bubble induced fouling can be limited in a number of ways, the most effective being to maintain a high operating pressure in the equipment to ensure nucleation does not occur. Experiments conducted in this study showed that a pressure of 130 kPa.g was sufficient to suppress all bubble nucleation at the heated surface at a temperature of 90°C. Another method identified was the use of high linear fluid velocities to entrain any surface bubbles into the processing stream immediately upon nucleation. Linear velocities above 1.0 m/s were shown to achieve this goal in the miniature plate heat exchanger tested. However, this method is only partially successful because the local linear velocity varies with position in heat exchange equipment of complex geometries and can drop below the mainstream average velocity causing surface bubbles to form, especially in recirculation regions behind flow obstacles. A more reliable method, in situations where high operating pressures could not be used, involved conditioning the heated surface with a thin protein layer during the first few minutes of a run. Conditioning the surface resulted in bubble suppression even at high temperatures and low pressures, thus greatly extending the length of the induction period. Trials performed in this study showed that the addition of a proteolytic enzyme produced by psychrotrophic microbes greatly increased fouling. The enzyme destabilised the caseins which could attach directly to the heat exchange surface independently from the bubble fouling mechanism. Thus the quality of the milk is another important factor to consider. However, the addition of enzymes produced by thermophilic bacilli isolated from milk powder plants did not increase fouling. A theory describing the air bubble induced fouling mechanism is presented along with recommendations on how to reduce this fouling contamination in processing equipment.

Fouling of heat treatment equipment in the dairy processing industry is an expensive and persistent problem. The objective of this work was to develop a better understanding of the mechanisms of dairy fouling in heat exchangers and identify methods to control this build-up. This was part of a larger project investigating the interaction between spore-forming thermophilic bacilli (thermophiles) contamination and fouling deposits on internal surfaces of equipment. Two systems were developed to monitor the onset and build-up of fouling on the internal surfaces of two research heat exchangers. The first used a commercial sensor to measure the local heat flux and the temperature on the hot side of a plate type heat exchanger. The heat transfer coefficient was calculated and normalised with its value at the start of the run to reflect the contribution of fouling deposits to the thermal resistance, thus giving a real-time estimate of the rate of fouling. The second system used an energy balance over a tubular type heat exchanger and measured inlet and outlet temperatures to estimate the overall heat transfer coefficient thus giving a global measurement of fouling over the tubular heat exchanger. In both systems the plot of normalised heat transfer coefficient over time often stayed constant over an induction period, which was followed by a falling period indicative of growth in the fouling layer thickness and/or mass. Each system was validated by comparing the final value of the normalised heat transfer coefficient with direct measurements of fouling made at the end of a run namely: fouling deposit height for the local measurement and fouling deposit mass for the global measurement. The normalised heat transfer coefficient reported by each system correlated well with the corresponding direct measurement of the fouling layer. An important factor identified in this study was the effect of air bubble nucleation on fouling deposits. It was shown that bubbles that formed on the heated surface greatly reduced the length of the induction period to a matter of seconds rather than hours, as found in previous studies of fouling in the absence of surface bubbles. The rate of fouling was also enhanced while the bubbles remained at the surface. The structure of bubble type fouling layers was linked to the behaviour of the bubbles at the heated surface. Visual observations of these bubbles showed evidence of growth, vibration and coalescence during their period of attachment to the heated surface. Deposits from bubble type fouling consisted of all solid components found in the original milk solution, except lactose, in approximately the same ratio. By contrast fouling deposits reported in the literature with systems operating under the traditional protein denaturation mechanism were reported to consist mainly of whey proteins. Bubble induced fouling can be limited in a number of ways, the most effective being to maintain a high operating pressure in the equipment to ensure nucleation does not occur. Experiments conducted in this study showed that a pressure of 130 kPa.g was sufficient to suppress all bubble nucleation at the heated surface at a temperature of 90°C. Another method identified was the use of high linear fluid velocities to entrain any surface bubbles into the processing stream immediately upon nucleation. Linear velocities above 1.0 m/s were shown to achieve this goal in the miniature plate heat exchanger tested. However, this method is only partially successful because the local linear velocity varies with position in heat exchange equipment of complex geometries and can drop below the mainstream average velocity causing surface bubbles to form, especially in recirculation regions behind flow obstacles. A more reliable method, in situations where high operating pressures could not be used, involved conditioning the heated surface with a thin protein layer during the first few minutes of a run. Conditioning the surface resulted in bubble suppression even at high temperatures and low pressures, thus greatly extending the length of the induction period. Trials performed in this study showed that the addition of a proteolytic enzyme produced by psychrotrophic microbes greatly increased fouling. The enzyme destabilised the caseins which could attach directly to the heat exchange surface independently from the bubble fouling mechanism. Thus the quality of the milk is another important factor to consider. However, the addition of enzymes produced by thermophilic bacilli isolated from milk powder plants did not increase fouling. A theory describing the air bubble induced fouling mechanism is presented along with recommendations on how to reduce this fouling contamination in processing equipment.

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Orientadores: João Domingos Biagi, Benedito Carlos Benedetti / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-17T05:14:17Z (GMT). No. of bitstreams: 1 Domene_MariaPaula_D.pdf: 812193 bytes, checksum: 6448c4a1133ba5e015287838e5fe5573 (MD5) Previous issue date: 2010 / Resumo: As indústrias de sementes e alimentícias têm sofrido pressões do mercado para produção de matéria-prima segura em relação às contaminações físicas, químicas e biológicas. Um caminho inverso começa a ser percorrido, no qual se tira o foco apenas do controle da qualidade do produto final, iniciando-se o rastreamento de toda a cadeia produtiva, para que os processos possam ser controlados e medidas preventivas possam ser tomadas para melhoria da qualidade e diminuição dos prejuízos. Este modelo exige que normas e padrões sejam seguidos a fim de assegurar a inocuidade dos alimentos. Contudo, estas normas são eficientes quando utilizadas em sistemas que tenham algum nível de organização, mas o que se observa é que os produtores rurais não dominam as ferramentas gerenciais comprometendo o controle da qualidade. Um fator que é observado dentro de unidades de beneficiamento (UB) de grãos e de sementes é a variabilidade do produto recebido, em relação aos aspectos físicos e sanitários. Assim, com a finalidade de avaliar o processo de beneficiamento de milho, adequando-se ainda mais às exigências do mercado consumidor e da legislação, foi desenvolvido este trabalho conjunto entre a COPLACANA (Cooperativa dos Plantadores de Cana do Estado de São Paulo), sediada no município de Piracicaba-SP, FEAGRI/UNICAMP, ESALQ/USP e CATI. Foram realizados levantamentos para determinação dos pontos críticos de controle (PCCs) através da avaliação do sistema de beneficiamento de grãos de milho da UB da COPLACANA. Ao final do levantamento, foi observada a variabilidade do material recebido quanto aos grãos avariados e, baseado nesta variabilidade da matéria-prima, testou-se se as sujidades influenciariam nas propriedades físicas dos grãos. Buscando alternativas seguras na manipulação e para o meio ambiente, foi testado o efeito de óleos essenciais de espécies de Eucalyptus citriodora, E.camaldulensis e o efeito sinérgico na germinação de sementes. Ao final da pesquisa, foram determinados quatro pontos críticos de controle principais que deveriam ser trabalhados, sendo eles recepção, limpeza, secagem e armazenagem; já os pontos críticos de controle em relação à infraestrutura, ambiental e capacitação, são complementares. O grau de umidade dos grãos recebidos na UB apresentou umidade média de 18,5%, sendo o mês de fevereiro o mais crítico, o que pode ter influenciado na qualidade dos grãos em relação a grãos ardidos. O monitoramento nas fases de pré-colheita e colheita é recomendado para minimizar os danos imediatos e de ardidos nos grãos. Em relação às propriedades físicas, as porcentagens de sujidades influenciaram nos valores da massa aparente específica, velocidade terminal e o coeficiente de atrito para a chapa de concreto. O óleo essencial de Eucaliptus camaldulensis e sua interação com o óleo essencial de Eucaliptus citriodora não influenciaram negativamente na germinação das sementes. Os fungos Penicillium spp e Fusarium sp. Foram controlados pelos óleos essenciais de E. camaldulensis e E. citriodora / Abstract: The seed and food industries have suffered from market pressures to produce safe raw material in relation to physical contamination, chemical and biological weapons. A reverse path starts to go, in which it takes the focus only on the quality control of the final product, starting tracking the entire production chain, so that processes can be monitored and preventive measures can be taken to improve quality and reduction of losses. This model requires that rules and standards are followed to ensure food safety. However, these Standards are effective when used in systems that have some level of organization, but what is observed is that farmers do not dominate the managerial tools compromising quality control. One factor that is observed within processing units (UB) of grains and seeds is the variability of the product received in the physical aspects and health. Thus, in order to evaluate the process of maize improvement, adapting to the demands of even the consumer market and the legislation was developed this collaborative effort between the COPLACANA (Cane Growers Cooperative of State of São Paulo) based in Piracicaba- SP, FEAGRI /UNICAMP, ESALQ / USP and CATI. We raised the critical control points by evaluating the system of processing of corn from the UB COPLACANA. At the end of the survey, we observed the variability of the material received regarding damaged grains and decided to check the influence of dirt on the physical properties of the grains. Seeking alternatives for safe handling and the environment, it was decided to test the effect of essential oils of species of Eucalyptus citriodora, E.camaldulensis and synergistic effect on seed germination. At the end of the study, we determined four main critical control points that should be worked while they were receiving, cleaning, drying and storage, as the critical control points in relation to infrastructure, environmental and training are complementary. The moisture content of grain received at UB had average humidity of 18,5%, being the month February the most critical, which may have influenced the quality of grains for burning grains. The monitoring in the pre-harvest and harvest is recommended to minimize the immediate damage and rot in the grains. Regarding physical properties, the percentages of dirt influenced by the values of apparent specific mass, terminal velocity and the coefficient of friction for the concrete plate. The essential oil of Eucalyptus camaldulensis and this interaction with essential oil of Euclyptus citriodora had no effect germination. Penicillium spp and Fusarium sp were controlled by the essential oils of E. camaldulensis and E. citriodora / Doutorado / Tecnologia Pós-Colheita / Doutor em Engenharia Agrícola

No / Experimental observations of melt temperature profiles and melting performance of extruder screws are reported. A novel temperature sensor consisting of a grid of thermocouple junctions was used to take multiple temperature readings in real time across melt flow in a single screw extruder. Melt pressure in the die and power consumption were also monitored. Three extruder screws at a range of screw speeds were examined for a commercial grade of low density polyethylene. Results showed melt temperature fields at low throughputs to be relatively independent of screw geometry with a flat-shaped temperature profile dominated by conduction. At high throughputs, melting performance and measured temperature fields were highly dependent upon screw geometry. A barrier-flighted screw with Maddock mixer achieved significantly better melting than single flighted screws. Low temperature "shoulder" regions were observed in the temperature profiles of single-flighted screws at high throughput, due to late melting of the solid bed. Stability of the melt flow was also dependent upon screw geometry and the barrier-flighted screw achieving flow with lower variation in melt pressure and temperature. Dimensionless numbers were used to analyze the relative importance of conduction, convection, and viscous shear to the state of the melt at a range of extrusion conditions.