Brittle materials such as silicon, germanium, glass and ceramics are widely used in semiconductor, optical, micro-electronics and various other fields. Traditionally, grinding, polishing and lapping have been employed to achieve high tolerance in surface texture of silicon wafers in semiconductor applications, lenses for optical instruments etc. The conventional machining processes such as single point turning and milling are not conducive to brittle materials as they produce discontinuous chips owing to brittle failure at the shear plane before any tangible plastic flow occurs. In order to improve surface finish on machined brittle materials, ductile regime machining is being extensively studied lately. The process of machining brittle materials where the material is removed by plastic flow, thus leaving a crack free surface is known as ductile-regime machining. Ductile machining of brittle materials can produce surfaces of very high quality comparable with processes such as polishing, lapping etc. The objective of this project is to develop a comprehensive predictive model for ductile machining of brittle materials. The model would predict the critical undeformed chip thickness required to achieve ductile-regime machining. The input to the model includes tool geometry, workpiece material properties and machining process parameters. The fact that the scale of ductile regime machining is very small leads to a number of factors assuming significance which would otherwise be neglected. The effects of tool edge radius, grain size, grain boundaries, crystal orientation etc. are studied so as to make better predictions of forces and hence the critical undeformed chip thickness. The model is validated using a series of experiments with varying materials and cutting conditions. This research would aid in predicting forces and undeformed chip thickness values for micro-machining brittle materials given their material properties and process conditions. The output could be used to machine brittle materials without fracture and hence preserve their surface texture quality. The need for resorting to experimental trial and error is greatly reduced as the critical parameter, namely undeformed chip thickness, is predicted using this approach. This can in turn pave way for brittle materials to be utilized in a variety of applications.

We hypothesized that supplementation of dietary conjugated linoleic acid (CLA) and arginine singly or in combination would increase animal performance and meat quality by decreasing adiposity and increasing lean mass in growing-finishing pigs. Sixteen pigs (80 kg) were assigned to four treatments in a 2 x 2 factorial design, differing in dietary fatty acid and amino acid composition [control: 2.05% alanine (isonitrogenous control) plus 1% canola oil (lipid control); CLA: 2.05% alanine + 1% CLA; arginine: 1% arginine + 1% canola oil; arginine + CLA: 1% arginine + 1 CLA]. Preliminary tests indicated that up to 2% arginine was acceptable without interfering with lysine absorption. Pigs were allowed to feed free choice until reaching 110 kg. There were no significant differences across treatments in feed intake, weight gain, or feed efficiency. CLA tended to decrease carcass length (P = 0.06), whereas backfat thickness tended to be greater in pigs supplemented with arginine (P = 0.08). Arginine decreased muscle pH at 45 min postmortem (P = 0.001) and tended to increase lightness of muscle at 24 h postmortem (P = 0.07). CLA supplementation increased the concentrations of trans-isomers of 18:1 (P = 0.001) and SFA (P = 0.01) in s.c. and r.p. adipose tissue. CLA supplementation increased palmitate incorporation into total lipids in longissimus muscle (P = 0.01). Glucose oxidation to CO₂ in r.p. and s.c. adipose tissue were greater in pigs supplemented with CLA in the absence or presence of arginine (P = 0.03 and P = 0.04, respectively). The volume of s.c. adipocytes in s.c. and r.p. adipose tissues was greater in pigs supplemented with CLA, arginine, or CLA plus arginine than in control pigs (P = 0.001). Neither CLA nor arginine affected the expression of PGC-1[alpha],AMPK, mTOR, CPT-1A, FAS, or SCD (P > 0.05) in any tissues. We conclude that there was no significant interaction between arginine and CLA. Supplementary CLA or arginine to finishing-growing pigs did not modulate growth performance and did not reduce adiposity. CLA increased intramuscular fat content without deteriorating meat quality traits and increased saturated fatty acids and substrate oxidation in adipose tissues. In the presence of 1% of canola oil or CLA in the diet, arginine has the potential to deteriorate meat quality by reducing early postmortem pH and by increasing carcass fatness.

<p>As a part of a more extensive project of developing a new finishing line at the Bolivian door manufacturer Tecno Carpinteria San Pedro this thesis presents the development process for a special designed spray booth. The thesis covers every phase from a product idea to a final concept design.</p><p>Working with finishing of furniture and other wooden products can effect the workers health in a negative way and damage the environment. The final result of the manufactured door is also depending on the how well the ventilation system in the working area is. Because of these reasons it is important to use safety equipment and a good ventilation system in the working area. As a part of this new finishing line San Pedro is in need of a special designed spray booth to control the spread of paint particles and other hazard substances that is a result of the finishing process.</p><p>Together with the consultant firm CADEFOR a spray booth is designed and a proposal design is presented in this thesis. The result is a design built up with a dry filter solution together with an extractor that creates a cross draft airflow towards the rear part of the spray booth. The result of the project together with some recommendations of increasing the capacity in the finishing line are also presented.</p>

M. Tech. Department of Chemical and Metallurgical Engineering. / Aims to understand and study the tribology and tribocorrosion behaviour of the adaptive titanium-nickel-zirconia composite coatings deposited on AISI 316 stainless steel using laser surface deposition technique under various laser processing speeds. The research aim is meant to be achieved through the following objectives: 1. Determine appropriate procedure for laser feedstock deposition ; 2. Investigate tribological performance of laser composites under various loads ; 3. Evaluate the corrosion of the laser composites coatings. and 4. Assess tribocorrosion behavior of the composite coatings

As a part of a more extensive project of developing a new finishing line at the Bolivian door manufacturer Tecno Carpinteria San Pedro this thesis presents the development process for a special designed spray booth. The thesis covers every phase from a product idea to a final concept design. Working with finishing of furniture and other wooden products can effect the workers health in a negative way and damage the environment. The final result of the manufactured door is also depending on the how well the ventilation system in the working area is. Because of these reasons it is important to use safety equipment and a good ventilation system in the working area. As a part of this new finishing line San Pedro is in need of a special designed spray booth to control the spread of paint particles and other hazard substances that is a result of the finishing process. Together with the consultant firm CADEFOR a spray booth is designed and a proposal design is presented in this thesis. The result is a design built up with a dry filter solution together with an extractor that creates a cross draft airflow towards the rear part of the spray booth. The result of the project together with some recommendations of increasing the capacity in the finishing line are also presented.

The surface-normal impact velocity distributions, impact frequencies and impact power per unit area were measured using a force sensor in a vibratory finisher for two types of spherical media. These parameters control the degree, rate and character of plastic deformation of a workpiece surface in vibratory finishing. The force sensor was also used to quantify the effect of media type, finisher amplitude, and location within the finisher on the probability distribution of the particle impact velocity normal to the workpiece. It was found that reducing the total media mass in the finisher and moving closer to the wall resulted in a more aggressive process. It was also found that contacts occured periodically within time periods that corresponded to the finisher’s driving frequency. The Almen system was adapted to a vibratory finishing process to characterize the effect of varying process parameters for the purposes of process development and control. Saturation curves for two types of aluminum Almen strips were obtained by finishing at two distinct conditions. Comparison with the normal contact forces and effective impact velocities, measured for both these conditions, provided insight into the mechanics of the vibratory finishing process. An electromagnetic apparatus was constructed to simulate the normal impacts in the vibratory finisher. It was found that surface-normal impacts at velocities comparable to the higher range in the vibratory finisher produced Almen saturation curves similar to those created in the vibratory finisher. This provided support for the modeling approximation of treating all contact events in a vibratory finisher as effective surface-normal impacts, and the accuracy of the effective impact velocity measurement. A model of the process by which Almen strips were plastically deformed by media impacts in vibratory finishing was presented. The motivation was to extend the use of Almen strip measurements as a means of characterizing vibratory finishing through an improved understanding of the process parameters that controlled time-dependent curvature development. Two thicknesses of Almen strip were tested for two finishing conditions. The quantitative agreement between the model saturation curves and the experimental curves was fair, although the overall trends were predicted very well.

The surface-normal impact velocity distributions, impact frequencies and impact power per unit area were measured using a force sensor in a vibratory finisher for two types of spherical media. These parameters control the degree, rate and character of plastic deformation of a workpiece surface in vibratory finishing. The force sensor was also used to quantify the effect of media type, finisher amplitude, and location within the finisher on the probability distribution of the particle impact velocity normal to the workpiece. It was found that reducing the total media mass in the finisher and moving closer to the wall resulted in a more aggressive process. It was also found that contacts occured periodically within time periods that corresponded to the finisher’s driving frequency. The Almen system was adapted to a vibratory finishing process to characterize the effect of varying process parameters for the purposes of process development and control. Saturation curves for two types of aluminum Almen strips were obtained by finishing at two distinct conditions. Comparison with the normal contact forces and effective impact velocities, measured for both these conditions, provided insight into the mechanics of the vibratory finishing process. An electromagnetic apparatus was constructed to simulate the normal impacts in the vibratory finisher. It was found that surface-normal impacts at velocities comparable to the higher range in the vibratory finisher produced Almen saturation curves similar to those created in the vibratory finisher. This provided support for the modeling approximation of treating all contact events in a vibratory finisher as effective surface-normal impacts, and the accuracy of the effective impact velocity measurement. A model of the process by which Almen strips were plastically deformed by media impacts in vibratory finishing was presented. The motivation was to extend the use of Almen strip measurements as a means of characterizing vibratory finishing through an improved understanding of the process parameters that controlled time-dependent curvature development. Two thicknesses of Almen strip were tested for two finishing conditions. The quantitative agreement between the model saturation curves and the experimental curves was fair, although the overall trends were predicted very well.

No description available.

No description available.

Orientador: Heraldo César Gonçalves / Banca: Simone Fernandes / Banca: Mauro Sartori Bueno / Resumo: Este trabalho foi realizado com o objetivo de avaliar o crescimento relativo dos cortes comerciais e dos tecidos da carcaça de caprinos. Foram utilizados 78 cabritos, machos e fêmeas, de cinco grupos raciais: Alpino; 1/2 Boer + 1/2 Alpino (1/2 BA); 1/2 Anglo Nubiano + 1/2 Alpino (1/2 ANA); 3/4 Boer + 1/4 Alpino (3/4 BA); e ½ Anglo Nubiano + ¼ Boer + ¼ Alpino (TC). Os grupos foram distribuídos em dois sistemas de terminação, pasto (ST1) e confinamento (ST2). Os cabritos foram abatidos em média aos 22,07 kg de peso vivo e 128,4 ± 7,9 dias. O peso médio das meias carcaças foi de 5,09 kg. Para determinação do crescimento alométrico foi utilizada a equação exponencial Y = aXb. O cruzamento com a raça Anglo Nubiana proporcionou o crescimento precoce da perna em relação ao peso da meia carcaça (PMC). O lombo cresceu tardiamente nos animais Alpinos e ½ ANA. Nos animais do grupo TC as costelas apresentaram crescimento tardio. Os cruzamentos não influenciaram no desenvolvimento do pescoço. A paleta foi considerada precoce nos animais ½ BA e TC. O tecido muscular, em relação ao PMC, apresentou crescimento precoce no grupo ½ BA. No ST1, a paleta cresceu precocemente, enquanto no ST2 este crescimento foi isogônico. O tecido adiposo dos animais do ST1 foi depositado tardiamente. As fêmeas apresentaram crescimento precoce de perna e tecido muscular, que nos machos foi considerado intermediário. O crescimento dos caprinos é influenciado pelos cruzamentos raciais, sistema de terminação e sexo / Abstract: This work was conducted with the objective of evaluate the relative growth of carcass cuts and tissues of goats. Seventy-eight male and female kids from five racial groups were used: Alpine; ½ Boer + ½ Alpine (½ BA); ½ Nubian + ½ Alpine (½ ANA); ¾ Boer + ¼ Alpine (¾ BA); and ½ Nubian + ¼ Boer + ¼ Alpine (TC); distributed in two finishing systems, pasture (FS1) and feedlot (FS2). The kids were slaughtered at an average of 22.07 kg of live weight and 128.4 ± 7.9 days. The average weight of half carcasses was 5.09 kg. To determine the allometric growth the exponential equation was used Y= aXb. The crossing with the Anglo Nubian provided the early growth of the leg in relation to the half carcass weight. The loin grew late in the Alpine animals and ½ the ANA. In animals from group TC ribs grew late. The crossings did not influence the development of the neck. The palette was considered earlier in kids ½ BA and TC. Muscle tissue in relation to the half carcass, grew early in the group ½ BA. In FS1, the palette grew early, while this growth was intermediate in FS2. The fat tissue of animals in FS1 had a late growth. The females showed early growth of leg and muscle tissue, while in males was considered intermediate. The growth of goats is influenced by the crossings, sex and finishing system / Mestre