Thesis (Ph. D.)--Institute of Paper Chemistry, 1949. / Includes bibliographical references (p. 104-106).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1966. / Includes bibliographical references (p. 109-112).

The main objective of the project was to develop a model for the motion of granular media under vibration in a tub vibrator. For such a system, it was decided that a discrete element method (DEM) was the most appropriate tool to model bulk velocity and circulation of media. In the first phase of the work, a vibratory finisher was modified to introduce planar vibration into a single layer of particles. The motion of the tub was measured using accelerometers and the corresponding granular media behavior was determined by video recording. A discrete element model, based on Cundall’s approach to contact, was developed to model granular flow in different vibratory beds, and the results were compared with experimental measurements of bulk flow velocity and bed expansion for the tub finisher. The sensitivity of the model predictions to the contact parameters was considered and the parameters were optimized with respect to the experimental results. After optimization, the difference between the model predictions of the bulk flow velocity and the measurements was less than 20% at four locations in media beds of two depths. The average bulk density of the vibrating beds was also predicted to be within 20% of the measured values. In the next phase, a two-dimensional discrete element model was developed to model single-cell circulation in vibratory beds that had both vertical and horizontal components of motion. The model predictions were compared with experimental measurements of the onset and growth of circulation in beds of steel and glass spheres as a function of bed depth, inter-particle and wall friction coefficients, and the amplitude of vibration. While the values from the DEM showed an error of up to 50% in the predicted circulation strength, depending on the type of the media and system conditions, the trends predicted by the model closely matched those in the experiments. Finally, a physical model was developed to describe the relationship between the onset and direction of circulation with the vibration of the container. A similar model was used to describe the experimental results as well as the transition in circulation patterns in terms of the resultant shear forces at the vibrating container walls and the interlocking of media close to the container walls. It was also demonstrated that a two-dimensional DEM could model a granular flow in which the media had three-dimensional contact and freedom of movement, but that was driven by vibrations in a plane. In summary, it was found that the linear optimization procedure for the contact parameters is an efficient way to improve the results from DEM. Additionally, the circulation in a tub-vibrator increased with the depth of the particulate media in the container, and with the magnitude of the wall-particle and particle-particle friction coefficients. The strength of circulation also increased with the amplitude of vibration. A strong correlation existed between the total shear force along the vibrating container walls and the circulation behavior. Bulk circulation increased sharply when increasing bed depth increased the pressure and the shear forces at the walls and between particle layers. It was also concluded that dimensionless bed depth (the ratio of bed depth to particle diameter) was not a proper dimensionless group when discussing the circulation behavior and it should act in conjunction with other parameters.

The main objective of the project was to develop a model for the motion of granular media under vibration in a tub vibrator. For such a system, it was decided that a discrete element method (DEM) was the most appropriate tool to model bulk velocity and circulation of media. In the first phase of the work, a vibratory finisher was modified to introduce planar vibration into a single layer of particles. The motion of the tub was measured using accelerometers and the corresponding granular media behavior was determined by video recording. A discrete element model, based on Cundall’s approach to contact, was developed to model granular flow in different vibratory beds, and the results were compared with experimental measurements of bulk flow velocity and bed expansion for the tub finisher. The sensitivity of the model predictions to the contact parameters was considered and the parameters were optimized with respect to the experimental results. After optimization, the difference between the model predictions of the bulk flow velocity and the measurements was less than 20% at four locations in media beds of two depths. The average bulk density of the vibrating beds was also predicted to be within 20% of the measured values. In the next phase, a two-dimensional discrete element model was developed to model single-cell circulation in vibratory beds that had both vertical and horizontal components of motion. The model predictions were compared with experimental measurements of the onset and growth of circulation in beds of steel and glass spheres as a function of bed depth, inter-particle and wall friction coefficients, and the amplitude of vibration. While the values from the DEM showed an error of up to 50% in the predicted circulation strength, depending on the type of the media and system conditions, the trends predicted by the model closely matched those in the experiments. Finally, a physical model was developed to describe the relationship between the onset and direction of circulation with the vibration of the container. A similar model was used to describe the experimental results as well as the transition in circulation patterns in terms of the resultant shear forces at the vibrating container walls and the interlocking of media close to the container walls. It was also demonstrated that a two-dimensional DEM could model a granular flow in which the media had three-dimensional contact and freedom of movement, but that was driven by vibrations in a plane. In summary, it was found that the linear optimization procedure for the contact parameters is an efficient way to improve the results from DEM. Additionally, the circulation in a tub-vibrator increased with the depth of the particulate media in the container, and with the magnitude of the wall-particle and particle-particle friction coefficients. The strength of circulation also increased with the amplitude of vibration. A strong correlation existed between the total shear force along the vibrating container walls and the circulation behavior. Bulk circulation increased sharply when increasing bed depth increased the pressure and the shear forces at the walls and between particle layers. It was also concluded that dimensionless bed depth (the ratio of bed depth to particle diameter) was not a proper dimensionless group when discussing the circulation behavior and it should act in conjunction with other parameters.

No description available.

No description available.

Thesis (Ph. D.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

ANDREW R. COURSEY, for the Master of Science degree in Zoology, presented 24 June 2011 at Southern Illinois University Carbondale TITLE: ALTERNATIVE FEEDING STRATEGIES TO MAXIMIZE MARINE FEEDSTUFF REPLACEMENT IN LARGEMOUTH BASS Micropterus salmoides CULTURE WHILE MAINTAINING PRODUCTION PERFORMANCE Advisors: Chris Kohler and Jesse Trushenski Harvest of marine resources for feedstuff production is at its maximum sustainable yield and alternative feedstuffs are needed to supply livestock production for an expanding human population having a growing desire for seafood. Aquaculture is currently the fastest growing sector of agriculture, but the high cost and limited supplies of marine feedstuffs for aquafeeds could ultimately limit production of foodfish. Replacement of marine feedstuffs poses a dilemma, however, as replacement of fish meal can affect animal growth, and replacement of fish oil in aquafeeds leads to altered fillet fatty acid profiles without the maximum benefit of high omega-3 (n-3) and long-chain polyunsaturated fatty acids (LC-PUFA) content. Two feeding trials were conducted to determine if poultry byproducts can replace fish meal and fish oil in diets for largemouth bass Micropterus salmoides without affecting production performance or fillet fatty acid composition. Poultry byproducts were able to replace fish meal and fish oil while maintaining production performance of largemouth bass, however, the altered fatty acid profiles of the feeds were reflected in the fillets. Finishing diets containing high levels of fish oil were implemented to restore n-3 and LC PUFA concentrations in the fillet. Twelve weeks of finishing proved suitable to partially restore n-3 and LC-PUFA concentrations while limiting the overall use of marine resources in the largemouth bass production cycle.

Cobia (Rachycentron canadum) aquaculture is poised for expansion, due in part to rapid growth rate, tolerance of culture conditions, and high market value of this species. Similar to other carnivorous marine fishes, the high monetary cost and long-range unsustainability of reliance on fish oil as the principle lipid source for cobia feeds necessitates evaluation of alternative lipid sources to spare or replace fish oil. Unfortunately, alternative lipid-based feeds may affect production performance, and typically yield fillets with reduced levels of long-chain polyunsaturated fatty acids (LC-PUFAs) such as docosahexaenoic acid (DHA, 22:6n-3). Recent research has indicated that diets rich in saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs), coupled with the application of so-called "finishing feeds" (feeds containing elevated levels of fish oil relative to grow-out feeds) at the end of the production cycle, may limit or attenuate these effects of fish oil sparing. Accordingly, I conducted two trials to evaluate the usefulness of alternative lipids and finishing in cobia culture. In the first trial, I assessed growth performance and tissue fatty acid composition of juvenile cobia fed diets (~11% lipid, ~48% protein) containing fish oil (control), or 50/50 blends of fish oil and alternative lipids (beef tallow, pork lard, partially and fully hydrogenated soy oils, and traditional soy oil) supplemented with an algal meal (to meet the 22:6n-3 requirement of cobia) for 8 weeks. Although minor differences were observed in feed intake, growth performance was otherwise equivalent among the dietary groups. Tissue fatty acid composition varied significantly among treatments, however, with alternative lipids containing higher levels of saturated (SFAs) and monounsaturated fatty acids (MUFAs) yielding tissue profiles that were most similar to those associated with the fish oil-based control feed. Although beef tallow and hydrogenated soybean oil were largely equivalent in terms of growth performance and fatty acid profile change, beef tallow was selected for further evaluation because of its low cost. In the second trial, beef tallow replaced fish oil in feeds at one of four substitution levels: 0% (100% fish oil), 33%, 67%, or 100% tallow (with algal 22:6n-3 meal included in all feeds as before). Juvenile cobia were raised on these feeds for 8 weeks, then switched to the 100% fish oil-based control feed for an 8-week finishing period. During finishing, subsamples of fish were collected every 2 weeks to quantify changes in tissue fatty acid profile over time as a result of finishing. In the second trial, the overall similarity of tissue fatty profiles to those in the 100% fish oil control treatment increased over the course of finishing, mostly as a result of declines in SFAs and MUFAs. These results suggest that SFA and MUFA-rich lipids, such as fully hydrogenated soy oil and beef tallow, are effective and strategically valuable as partial substitutes for fish oil in cobia feeds, and that finishing is at least partially effective in restoring cobia tissue fatty acid composition to a state approximating that of cobia fed only fish oil as dietary lipid.

Given the routine use of polishing and finishing systems in Restorative Dentistry, the search for better outcomes of these materials, it is essential to optimize the results. Thus, this study aimed to evaluate in vitro the effect of polishing finishing and polishing systems on surface roughness of composite resin. Specimens were made for each group (n = 10), totaling 80 specimens. Randomly distributed among the eight selected polishing systems. The polishing systems were employed after the stabilize the polishing and metallographic specimens was followed according to the manufacturer's instructions. The specimens were stored for 24 hours in aqueous solution (room temperature) underwent evaluation of roughness on rugosimeter, and surface roughness as groups were compared using ANOVA, followed by post-hoc Tukey test at a significance level 5%, with p = 0.05. Was no statistical difference between finishing and polishing systems evaluated. The finishing and polishing systems produce different patterns on the surface roughness of the composite, and the rotating disc systems based on superior results obtained with smaller surface roughness measurements. / Tendo em vista o uso rotineiro dos sistemas de polimento e acabamento na Odontologia Restauradora, a busca por melhores resultados destes materiais, é essencial a fim de otimizar os resultados. Assim, este estudo teve como objetivo avaliar in vitro, o efeito de polimento de sistemas de acabamento e polimento na rugosidade superficial de resina composta. Foram confeccionados corpos de prova para cada grupo (n=10), totalizando 80 espécimes. Distribuídos aleatoriamente entre os 8 sistemas de polimento selecionados. Os sistemas de polimento foram empregados após a regularização dos espécimes em politriz metalográfica e foi seguido conforme as instruções do fabricante. Os espécimes foram armazenados por 24 horas em solução aquosa, (temperatura ambiente) submetidos a avaliação de rugosidade no rugosímetro, e os grupos foram comparados quanto a rugosidade superficial por meio de ANOVA, seguido de teste de Post-Hoc de Tukey ao nível de significância de 5%, com p≤0,05. Houve diferença estatística entre os sistemas de acabamento e polimento avaliados. Os sistemas de acabamento e polimento produzem diferentes padrões de rugosidade na superfície da resina composta, sendo que os sistemas baseados em discos rotatórios obtiveram resultados superiores, com menores medidas de rugosidade superficial.