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Tribocorrosion mechanisms in laser deposited titanium-based smart composite coatingsObadele, Babatunde Abiodun January 2014 (has links)
D. Tech. Chemical, Metallurgical and Materials Engineering. / Aims to produce and improve the tribocorrosion property of Ti6Al4V by means of laser surface cladding with Ni and ZrO2. The results of this study would be useful for the design of high performance components for chemical and oil industry and potential applications in other engineering fields. The aim would be achieved through the following objectives: 1. Synthesize and characterise Ti, Ti-Ni and Ti-Ni-ZrO2 admixed powders. 2. Explore the feasibility of laser surface treatment of Ti6Al4V with Ti, Ti-Ni and Ti-Ni-ZrO2. 3. Investigate possible metallurgical interactions and phenomenon during and after laser surface cladding of the composite. 4. Evaluate the microstructural and mechanical properties of Ti based composites in terms of hardness. 5. Analyze the interaction between wear and corrosion wear as well as tribocorrosion resistance of the alloys and composites after laser surface cladding in 3.5 % NaCl and 1M H2SO4 environments.
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Promoting the "classroom and playground of Europe": Swiss private school prospectuses and education-focused tourism guides, 1890-1945Swann, Michelle 05 1900 (has links)
Since the late nineteenth century, Switzerland, a self-professed “playground” and “classroom” of the world, has successfully promoted itself as a desirable destination for international study and tourism. The historically entangled private schooling and tourism industries have steadily communicated idealised images of educational tourism in Switzerland via advertising. Concentrating on the period 1890 -1945 – when promotional ties between tourism organisations and private schools solidified – this thesis investigates the social construction of educational tourist place in two different types of promotion aimed at English-speaking markets: private international school prospectuses and education-focused tourism brochures. An analysis of early prospectuses from three long-standing private international schools and of education-focused tourism guides written by municipal organisations, travel agencies, school boards and the Swiss government revealed highly visual, ideologically-charged textual representations of locations and markets simultaneously defined, idealised and commodified international education in Switzerland. Chapters provide close interpretation of documents and aim, through thick description, to understand specific place-making examples within a wider socio-historical context. Chapter One examines the earliest prospectuses of Le Rosey and Brillantmont, two of the world’s must exclusive Swiss schools (1890-1916). An examination of photo-essay style prospectuses reveals highly selective portrayals of “Château” architecture communicated capacity to deliver a “high-class” and gender appropriate Swiss finishing. Visual cues hallmarking literary and sporting preferences indicated texts catered to the gaze of social-climbing, Anglo-centric markets desirous a continental cosmopolitan education that was not overly “foreign.” Chapter Two analyses the social construction of towns in French-speaking Switzerland as attractive educational centres (1890-1914). It explores how guides promoting Geneva, Neuchâtel and Lausanne constructed an idealised study-abroad landscape through thematic testaments to the educative capacities of local human and natural landscapes. The remaining chapters explore interwar texts. Chapter Three examines a high-altitude institute’s use of the idealising skills of high-end tourism poster artists to manufacture a pleasant, school-like image for the mountain sanatoria-like campus of Beau Soleil. Chapter Four investigates two series of education-focused tourism guidebooks which promoted education in Switzerland. An examination of a Swiss National Tourist Office series reveals discourses of nationhood racialised the Swiss as natural-born pedagogues and constructed Switzerland as a safe, moral destination populated by cooperative, multi-lingual and foreign student-friendly folk. An analysis of R. Perrin Travel Agency’s series explores guidebooks which openly classified education as a tourism commodity. The final chapter examines Le Rosey and Brillantmont’s interwar prospectuses within the context of complex, transnational schooling and school advertising practices. An analysis of images of school sports at winter holiday resorts suggests prospectuses expressed the sense of freedom which accompanies upper-class identity more so than any sense of gender-driven restriction.
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Evaluation of secondary wire bond integrity on silver plated and nickel/palladium based lead frame plating finishesSrinivasan, Guruprasad. January 2008 (has links)
Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2008. / Includes bibliographical references.
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Méthodologie de minimisation de la pollution appliquée au traitement de surface : étude de l’entraînement comme vecteur de pollution / Methodology of pollution minimization for metal finishing industry : study of drag-out as a pollution vectorLeveillard, Florine 03 February 2011 (has links)
Dans un contexte réglementaire incitant fortement les industriels à la réduction de la pollution à la source, l’application de stratégies telles que des bonnes pratiques environnementales et un meilleur contrôle des procédés constituent une réponse aux enjeux environnementaux. Le traitement de surface par voie aqueuse est une activité grande consommatrice d’eau et de produits chimiques et donc génératrice de rejets aqueux pollués. L’objectif de ce travail est de proposer à ce secteur d’activité une méthodologie simple de limitation des flux de pollution ainsi que de la consommation en eau. Cette méthodologie se base notamment sur le postulat que l’entraînement est le principal vecteur de pollution au sein d’une chaîne de traitement de surface.Des études expérimentales ont permis, d’une part de créer une méthode rapide de calcul de l’entraînement et, d’autre part, de montrer et de quantifier l’influence de la forme et de la rugosité des pièces traitées, du temps d’égouttage, de la tension superficielle des solutions de traitement ou encore du type et de la durée du rinçage des pièces sur l’entraînement.L’ensemble de ces éléments, intégrés à la méthodologie de minimisation de la pollution, permet d’une part de réaliser un diagnostic de la chaîne mais aussi d’estimer l’impact d’une modification de cette chaîne sur la consommation spécifique en eau, le bilan de pollution ainsi que sur la qualité des rinçages. Cette méthodologie aide ainsi à limiter les consommations d’eau et de réactifs non seulement sur la chaîne mais également en station de détoxication, diminuant ainsi les impacts environnementaux et les coûts de fonctionnement. / Currently, via the prevention principle, environmental regulations incite industries to implement strategies to reduce the pollution at the source (ICPE, IPPC, IED). Industries are sometimes lost in front of various proposed technical solutions. The application of cleaner production strategies such as good operational procedures and good practices of management allow to answer these constraints.The metal finishing activity uses a lot of water and chemicals and thus generates polluted effluents. The objective of this work is to propose a simple methodology of limitation of the pollution flows and of the water specific consumption of metal finishing workshops.Then, experimental studies have allowed, on one hand, to create an easy method of the drag-out calculation and, on the other hand, to show and to quantify the influence of different parameters on the drag-out, from a qualitative and quantitative point of view. They are, for example, the shape and the roughness of the treated pieces, the draining time, the superficial tension of the treatment solutions but also the stirring type and duration of rinsing.All these elements, integrated into the methodology of pollution minimization, allow to realize a diagnosis of the process line. Moreover, it permits to estimate the impact of a modification of this installation on the specific consumption of water, on the pollution balance assessment and on the rinsing quality. So, this methodology can help to optimize and to limit consumptions of water and chemicals not only on the process line but also in wastewater treatment plant, so decreasing the environmental impacts and the running costs.
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Aplicação de redes neurais artificiais no monitoramento da operação de dressagemGrizzo, Daniela Fernanda [UNESP] 06 July 2012 (has links) (PDF)
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moia_dfg_me_bauru.pdf: 2028523 bytes, checksum: a4957573090c9f2211022b6a4fceb9b6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O processo de retificação confere à peça o acabamento final, minimizando as irregularidades superficiais através de interações entre os grãos abrasivos de uma ferramenta (rebolo) e peça retificada. O desgaste do rebolo devido ao atrito entre o rebolo e a peça retificada torna a ferramenta inadequada para nova utilização, sendo necessária a realização do processo de dressagem do rebolo para remoção e ou avivamento dos grãos gastos de sua superfície de corte, de forma e deixá-lo em condições para novo uso. O presente trabalho tem como objetivo classificar a condição do rebolo durante a operação de dressagem utilizando o sinal de emissão acústica (EA) e estatísticas derivadas desse sinal, por meio de redes neurais artificiais. Nos experimentos realizados usou-se um rebolo de óxido de alumínio instalado em uma retificadora plana, um sistema de aquisição de sinais e um dressador de ponta única de diamante. O processamento digital de sinais foi obtido através do software MATLAB. Os ensaios foram realizados com diferentes graus de recobrimento e profundidade de dressagem. A partir dos dados obtidos de EA puro, calculou-se o valor médio quadrático (RMS), bem como mais duas estatísticas, as quais já foram empregadas com sucesso em trabalhos de detecção de queima, no processo de retificação. Essas estatísticas também se mostraram bons indicadores para o monitoramento da operação de dressagem. Uma rede neural perceptron multicamadas (MLP) foi utilizada com o algoritmo de aprendizado Levenberg-Marquardt, cujas entradas foram as duas estatísticas mencionadas e o valor RMS de EA. Os resultados mostram que o método empregado foi capaz de classificar as condições do rebolo no processo de dressagem, identificando o rebolo como afiado (com capacidade de corte) e rebolo se afiação (com perda de capacidade de corte), viabilizando a redução do tempo e custo dessa operação e minimizando a remoção excessiva / The grinding process gives the piece a final finish by minimizing surface irregularities through interactions between the abrasive grains of a tool (wheel) and the part to be ground. The wear of the grinding wheel due to excessive friction between the grinding wheel and ground workpiece makes the tool unsuitable for further use; it is imperative the accomplishment of the process of dressing the grinding wheel to remove or resharpen the worn grains of its surface in order to make if suitable for use again. The present study aims to classify the condition of the grinding wheel during operation using acoustic emission (AE) signal and statistics derived from this sinal through artificial neural networks. In the experiments an aluminum oxide grinding wheel installed to a surface grinding machine was used along with a data acquisition system and a single point diamond dresser. The digital processing of these data was obtained using the MATLAB software. Tests were performed with different overlap ratio and depth of cut. The root mean square value of the AE signal as well as two other statistics were obtained from the raw acoustic emission signal, which have been successfully used in grinding burn detection. These statistics were also good indicators for monitoring the dressing operation. A multilayer perceptron neural network (MLP) was used with the learning algorithm Levenberg-Marquardt, whose inputs were the statistics previously mentioned and dressing conditions. The results show that the method used was able to classify the conditions of the grinding wheel in the process of dressing, identifying the wheel as sharp (cutting capacity) and dull (with loss of cutting capacity), enabling the reduction of time and cost of operation and minimizing the excessive removal of the wheel abrasive material
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Fósforo disponível em dietas com ou sem ractopamina para fêmeas suínas em terminação tardia / Available phosphorus in diets with or without ractopamine for finishing giltsCampos, Priscila Furtado 10 February 2010 (has links)
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Previous issue date: 2010-02-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With the objective to evaluate levels of available phosphorus in diets with or without ractopamina, were used 112 gilts with high genetic potential for meat deposition with initial weigh of 94.00 ± 2.28 kg distributed in a completely randomized block design, in a 4x2 factorial scheme (0,109; 0,209; 0,309; e 0,409% of available phosphorus and 0 or 10 ppm with ractopamine) with eight treatments, seven replications and two animals per experimental unit. There was not interaction between levels of phosphorus and ractopamina. The levels of available phosphorus have influenced the daily weight gain and the daily phosphorus intake with increase in a linear form. The feed conversion improved in a quadratic form until with the increase of the available phosphorus levels, until the estimated level of 0.33% of available phosphorus. The ractopamina provided increase in the daily weigh gain and decrease in the feed conversion. The alkaline phosphatase decreased in a linear form with the increase of the available phosphorus levels. The levels of available phosphorus have influenced the bone resistence with increased in a quadratic form until the estimated level of 0.32%. The contents of ash, calcium and phosphorus in the bone increased in a quadratic form until the estimated levels, respectively 0.270; 0.277 e 0.295% of available phosphorus. It was concluded that the level of available phosphorus for gilts of high potential for meat deposition, from 94 to 125 kg, is 0.33%, with corresponds to an available phosphorus intake of 8.67 g day, in diets with 10 ppm of ractopamine. / Com o objetivo de avaliar níveis de fósforo disponível em dietas suplementadas ou não com ractopamina, foram usadas 112 leitoas de alto potencial genético para deposição de carne magra com peso inicial de 94,0 ± 2,28 kg, em um experimento com delineamento experimental de blocos ao acaso, em esquema fatorial 4x2 (0,109; 0,209; 0,309; e 0,409% de fósforo disponível e com 0 ou 10 ppm de ractopamina), perfazendo oito tratamentos, com sete repetições e dois animais por unidade experimental. Não foi observada interação entre os níveis de fósforo disponível e ractopamina para nenhum dos parâmetros estudados. Os níveis de fósforo disponível influenciaram o consumo de fósforo disponível e o ganho de peso diário que aumentaram de forma linear. A conversão alimentar melhorou de forma quadrática com o aumento dos níveis de fósforo disponível na dieta, até o nível estimado de 0,33% de fósforo disponível. A ractopamina proporcionou aumento no ganho de peso e diminuição da conversão alimentar. A atividade da fosfatase alcalina no soro diminuiu de forma linear com o aumento dos níveis de fósforo disponível na dieta. Os níveis de fósforo disponível influenciaram a resistência óssea que aumentou de forma quadrática, até o nível estimado de 0,32%. Os teores de cinza cálcio e fósforo no osso foram influenciados de forma quadrática até os níveis estimados, respectivamente de 0,270; 0,277 e 0,295% de fósforo disponível. Concluiu-se que o nível de fósforo disponível para fêmeas suínas de alto potencial para deposição de carne, dos 94 aos 125 kg, é de 0,33%, correspondente a um consumo diário de 8,67 g em dietas com até 10 ppm de ractopamina.
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Aplicação de redes neurais artificiais no monitoramento da operação de dressagem /Grizzo, Daniela Fernanda. January 2012 (has links)
Orientador: Paulo Roberto de Aguiar / Banca: Carlos Elias da Silva Junior / Banca:m Eduardo Carlos Bianchi / Resumo: O processo de retificação confere à peça o acabamento final, minimizando as irregularidades superficiais através de interações entre os grãos abrasivos de uma ferramenta (rebolo) e peça retificada. O desgaste do rebolo devido ao atrito entre o rebolo e a peça retificada torna a ferramenta inadequada para nova utilização, sendo necessária a realização do processo de dressagem do rebolo para remoção e ou avivamento dos grãos gastos de sua superfície de corte, de forma e deixá-lo em condições para novo uso. O presente trabalho tem como objetivo classificar a condição do rebolo durante a operação de dressagem utilizando o sinal de emissão acústica (EA) e estatísticas derivadas desse sinal, por meio de redes neurais artificiais. Nos experimentos realizados usou-se um rebolo de óxido de alumínio instalado em uma retificadora plana, um sistema de aquisição de sinais e um dressador de ponta única de diamante. O processamento digital de sinais foi obtido através do software MATLAB. Os ensaios foram realizados com diferentes graus de recobrimento e profundidade de dressagem. A partir dos dados obtidos de EA puro, calculou-se o valor médio quadrático (RMS), bem como mais duas estatísticas, as quais já foram empregadas com sucesso em trabalhos de detecção de queima, no processo de retificação. Essas estatísticas também se mostraram bons indicadores para o monitoramento da operação de dressagem. Uma rede neural perceptron multicamadas (MLP) foi utilizada com o algoritmo de aprendizado Levenberg-Marquardt, cujas entradas foram as duas estatísticas mencionadas e o valor RMS de EA. Os resultados mostram que o método empregado foi capaz de classificar as condições do rebolo no processo de dressagem, identificando o rebolo como "afiado" (com capacidade de corte) e rebolo "se afiação" (com perda de capacidade de corte), viabilizando a redução do tempo e custo dessa operação e minimizando a remoção excessiva / Abstract: The grinding process gives the piece a final finish by minimizing surface irregularities through interactions between the abrasive grains of a tool (wheel) and the part to be ground. The wear of the grinding wheel due to excessive friction between the grinding wheel and ground workpiece makes the tool unsuitable for further use; it is imperative the accomplishment of the process of dressing the grinding wheel to remove or resharpen the worn grains of its surface in order to make if suitable for use again. The present study aims to classify the condition of the grinding wheel during operation using acoustic emission (AE) signal and statistics derived from this sinal through artificial neural networks. In the experiments an aluminum oxide grinding wheel installed to a surface grinding machine was used along with a data acquisition system and a single point diamond dresser. The digital processing of these data was obtained using the MATLAB software. Tests were performed with different overlap ratio and depth of cut. The root mean square value of the AE signal as well as two other statistics were obtained from the raw acoustic emission signal, which have been successfully used in grinding burn detection. These statistics were also good indicators for monitoring the dressing operation. A multilayer perceptron neural network (MLP) was used with the learning algorithm Levenberg-Marquardt, whose inputs were the statistics previously mentioned and dressing conditions. The results show that the method used was able to classify the conditions of the grinding wheel in the process of dressing, identifying the wheel as sharp (cutting capacity) and dull (with loss of cutting capacity), enabling the reduction of time and cost of operation and minimizing the excessive removal of the wheel abrasive material / Mestre
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Qualidade nutricional da carne de tourinhos nelore e ½ angus-nelore terminados em confinamento ou em pastagem com suplementação / Nutritional quality of meat of nelore and ½ angus-nelore steers finished in feedlot or on pasture with supplementationReis, Renata Cunha dos 06 March 2017 (has links)
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Previous issue date: 2017-03-06 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / It was aimed to verify the influence of genetics between Nelore or ½ Angus-Nelore animals and the finishing phase systems, pasture with protein-energy supplementation or feedlot, on the contents of moisture, ashes, proteins, fat, iron, zinc, calcium, potassium, pH, color, fatty acids composition, vitamin E, lipid oxidation and cholesterol of the meat of these animals, after reaching 480 kg body weight. It was adopted the completely randomized design, in 2x2 factorial arrangement, with two breeds and two finishing systems. Meat from feedlot finished ½ Angus-Nelore animals obtained higher protein content (P <0.05) than feedlot Nelore animals. The ½ Angus-Nelore animals finished on pasture with supplementation obtained meat with higher content (P <0.05) of zinc and lower content of linoleic acid (C18:2 n-6) compared to meat of Nelore steers finished on pasture with supplementation and feedlot finished ½ Angus-Nelore. For myristic acid, one of the fatty acids considered to be hypocholesterolemic, the treatment with meat of feedlot finished Nelore showed a higher value (P <0.05) when compared to Nelore finished on pasture with supplementation and feedlot finished ½ Angus-Nelore. Meat of Nelore steers finished on pasture with supplementation obtained higher values (P<0.05) for stearic (C18:0), linolenic (C18:3n-3), DHA and total polyunsaturated fatty acids when compared to feedlot finished Nelore. Isolatedly, (P <0.05), the feedlot system generated higher contents of C18:1 trans-10 cis-12 fat. The pasture combined with supplementation system contributed to higher values of calcium, potassium, trans-vaccenic acid (C18:1 trans-11 cis-9) and vitamin E. For the Nelore breed, they were found higher contents of fat and vitamin E, while the ½ Angus-Nelore showed higher amount of potassium. The analysis of moisture, ash, iron, pH, color, cholesterol, palmitic acid (C16:0), total saturated fatty acids and oleic acid (C18:1n-9) were not significant. According to the obtained results, it was concluded that, under the conditions of the present study, Nelore animals finished on pasture with supplementation resulted in meat with a higher content of polyunsaturated, mainly omega-3, fatty acids, when compared to feedlot finished Nelore, while the ½-Angus-Nelore finished on pasteure with supplementation, lower omega-6 content, whose characteristic is very important with regard to n-6 / n-3 ratio; and the pasture finishing system contributed, isolatedly, to higher contents of calcium, potassium, vitamin E and trans-vaccenic acid, which is an intermediate of the ruminal biohydrogenation process, shown to be beneficial to health, while the feedlot system contributed to an increased deposition of intramuscular fat and higher content of the trans isomer, which is harmful to health. / O objetivo deste estudo foi verificar a influência da genética entre animais Nelore ou ½ Angus-Nelore e do tipo de terminação, a pasto com suplementação proteico-energética ou confinamento, sobre os conteúdos de umidade, cinzas, proteínas, gordura, ferro, zinco, cálcio, potássio, pH, cor, composição de ácidos graxos, vitamina E, oxidação lipídica e colesterol das carnes destes animais, após atingirem 480 kg. O delineamento experimental utilizado foi o inteiramente ao acaso com arranjo fatorial 2x2, sendo duas raças e dois tipos de terminação. A carne de animais ½ Angus-Nelore quando terminados em confinamento obtiveram maior teor de proteína (P<0,05) em relação a de Nelore quando receberam confinamento. Animais ½ Angus-Nelore a pasto com suplementação obtiveram carnes com maior teor (P<0,05) de zinco e menor teor de ácido linoleico (C18:2 n-6) em relação a carne de animais Nelore terminados a pasto com suplementação e aos ½ Angus-Nelore terminados em confinamento. Para o ácido mirístico, um dos ácidos graxos considerados hipocolesterolêmicos, o tratamento com carne de animais Nelore terminados em confinamento adquiriu maior valor (P<0,05) quando comparado com Nelore terminado a pasto com suplementação e também ao ½ Angus-Nelore em confinamento. A carne de animais Nelore terminados a pasto com suplementação obteve maiores valores (P<0,05) para os ácidos esteárico (C18:0), linolênico (C18:3n-3), DHA e para o total de ácidos graxos poli-insaturados em relação ao Nelore terminado em confinamento. De forma isolada (P<0,05), o sistema de confinamento gerou maiores teores de gordura e C18:1 trans-10 cis-12. O sistema à pasto com suplementação contribuiu para maiores valores de cálcio, potássio, ácido trans-vacênico (C18:1 trans11 cis-9) e vitamina E. Para a raça Nelore foram encontrados maiores teores de gordura e vitamina E enquanto para os ½ Angus-Nelore maior quantidade de potássio. As análises de umidade, cinzas, ferro, pH, cor, colesterol, ácido palmítico (C16:0), total de ácidos graxos saturados e ácido oleico (C18:1n-9) não foram significativas. Dos resultados obtidos conclui-se que, nas condições do presente trabalho, animais Nelore terminados a pasto com suplementação gerou carne com maior composição de ácidos graxos poliinsaturados, principalmente de ômega-3, enquanto os ½ Angus-Nelore terminados a pasto com suplementação menor teor de ômega-6, cuja característica é muito importante no que se refere a relação n-6/n-3 e a terminação a pasto de forma isolada contribuiu para maior teor de cálcio, potássio, vitamina E e ácido trans-vacênico, intermediário do processo de biohidrogenação ruminal apontado como benéfico à saúde, enquanto o sistema de confinamento contribuiu para uma maior deposição de gordura intramuscular e maior teor do isômero trans apontado como maléfico à saúde.
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Inter-relationship of skin pass, 2D and 3D roughness parameters, stampability and paintability on cold rolled steel sheets for the automotive industry. / Inter-relação entre passe de acabamento, parâmetros de rugosidade 2D e 3D, estampabilidade e pintabilidade de chapas de aço laminada a frio para indústria automotiva.Eduardo Nunes 12 December 2013 (has links)
The aim of this research work is to study the inter-relationship, under controlled industrial conditions, among skin pass reductions, surface topography characterized by 2D and 3D roughness parameters, stampability and painted surface finish quality for automotive steel sheet stampings. Different surface textures obtained from cold rolling finishing have been evaluated in terms of paint appearance (rating and spectral curve) and tentatively related to roughness parameters (2D and 3D) obtained from the cold finished sheets. Some relevant tendencies have been established amongst these parameters. The results presented here are in accordance with other recently published research showing that there is a clear relationship between these parameters, and that further detailed studies are needed. / O foco do presente trabalho é o estudo, em condições industriais, da inter-relação entre grau de redução do passe de acabamento, topografia superficial caracterizada pelos parâmetros de rugosidade 2D e 3D, estampabilidade e aparência de pintura de chapas de aço para painéis automotivos. Diferentes texturas superficiais de chapas de aço foram analisadas em termos de aparência de pintura (rating e curvas espectrais) e tentativamente relacionadas com os parâmetros de rugosidades (2D e 3D) obtidos na chapa antes de estampar. Algumas tendências relevantes foram estabelecidas entre estes parâmetros. Os resultados presentes aqui estão de acordo com publicações recentes mostrando uma clara relação entre estes parâmetros e que trabalhos futuros ainda são necessários.
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Eficiência alimentar e características da carcaça e da carne de novilhos de diferentes genótipos terminados em dois sistemas alimentares. / Feed efficiency and carcass beef traits from steers of different genotypes in two feeding systems.Nunes, Marcelo Henrique Giordano 31 March 2011 (has links)
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Previous issue date: 2011-03-31 / The objective of this study was to evaluate feed efficiency and carcass and beef
quality of pure and crossbred genotypes, as well as the possible influence of the
finishing system on the beef physical-chemical and sensory traits. Steers of six
different genotypes, Aberdeen Angus (ANAN), Hereford (HHHH), Nellore
(NENE), Aberdeen Angus x Nellore (ANNE), Aberdenn Angus x Hereford
(ANHH) and Aberdeen Angus X Caracu (ANCR) were evaluated during
finishing in two different systems: feedlot or cultivated pasture. The steers
entered the finishing with an average age of 19.8 ± 0.91 months. Animals kept
in feedlot received a diet containing 40% concentrate and 60% of forage on a
dry matter basis. The roughages used were corn and sorghum silage mixed in
50:50 ratio. All supplied feed and the leftovers were weighed daily to estimate
daily intake of confined steers. Cattle finished on pasture was kept in a paddock
with cultivated oats and ryegrass. The slaughter criterion was a subcutaneous
fat thickness of at least 3 mm, measured at the weighing days by
ultrasound. Significant differences in feed efficiency were found between
studied genotypes. The animals of HHHH breed group were superior to the
ANAN and NENE animals in the residual feed intake evaluation obtaining the
respective values of -0.92 kg versus 0.73 and 0.70 kg. For feed conversion the
HHHH shower a smaller amount of feed intake per kilogram of weight gain
when compared to ANNE, ANCR and NENE (6.0 vs. 9.4, 8.5 and 10.9 kg,
respectively). The HHHH had the lowest dry matter intake, 7.4 kg, and did not
differ only of the NENE (8.5 kg). It was observed a smaller slaughter weight in
the NENE (403 kg), while ANNE and ANCR animals showed higher values for
chilled carcass weight (272 and 256 kg, respectively). In assessing the primary
cuts of the carcass, the NENE presented the lowest rib weight, 14 kg, when
compared to others genotypes. Regarding beef quality, the ANCR breed group
presented tenderer steaks than ANNE and NENE groups in the evaluation of
shear force (3.7 vs 5.9 e 6.9kgf, respectively). In sensory toughness attribute,
the beef of ANCR, ANHH and HHHH animals was considered tenderer than
NENE animals. Caracu breed can be used as an alternative to zebu in crossing
with British breeds showing comparable levels in quantitative aspects of
carcass, but with higher beef tenderness when compared to zebu breeds. In
this experiment conditions, the NENE showed low productivity and also poor
beef and carcass quality; nevertheless, it had superior performance in the
crossbreeding with Aberdeen Angus. / O objetivo deste estudo foi avaliar a eficiência alimentar e a qualidade da
carcaça e da carne de diferentes genótipos puros e cruzados, bem como a
possível influência do sistema de terminação nas características físicoquímicas
e sensórias da carne bovina. Para isso, utilizou-se novilhos de seis
diferentes genótipos, Aberdeen Angus (ANAN), Hereford (HHHH), Nelore
(NENE), Aberdeen Angus X Nelore (ANNE), Aberdeen Angus X Hereford
(ANHH) e Aberdeen Angus X Caracu (ANCR), terminados em dois diferentes
sistemas: confinamento intensivo ou pastagem cultivada. Os novilhos entraram
na terminação com idade média de 19,8±0,91 meses. Os animais mantidos em
sistema de confinamento receberam dieta composta por 40% de concentrado e
60% de volumoso com base na matéria seca. Como volumosos foram
utilizados silagem de milho e sorgo misturados em proporção de 50:50. O gado
terminado em pastagem foi mantido em potreiro consorciado com aveia e
azevém. O critério utilizado para abate foi à espessura de gordura subcutânea
mínima de 3 mm, mensurada junto com as pesagens por avaliações de ultrasonografia.
Foram encontradas diferenças significativas de eficiência alimentar
entre os genótipos estudados. Os animais do grupo racial HHHH apresentaram
melhor eficiência que os ANAN e NENE na avaliação de consumo alimentar
residual obtendo respectivos valores de -0,92 kg vs. 0,73 e 0,70 kg. Para a
conversão alimentar, o HHHH apresentou menor quantidade de alimento
consumido por quilograma de ganho de peso quando comparado aos ANNE,
ANCR e NENE (6,0 vs. 9,4, 8,5 e 10,9 kg, respectivamente). O HHHH também
apresentou o menor consumo de matéria seca, 7,4 kg, não diferindo (P>0,05)
apenas do NENE com 8,5 kg. Observou-se menor peso vivo ao abate nos
animais NENE (403 kg), enquanto os animais ANNE e ANCR apresentaram os
maiores valores para peso de carcaça fria (272 e 256 kg, respectivamente). Na
avaliação dos cortes primários da carcaça, o NENE apresentou peso de costela
mais leve quando comparado aos demais (14 kg). Quanto à qualidade da
carne, o grupo ANCR apresentou carne mais macia que os grupos ANNE e
NENE na avaliação de força de cisalhamento pelo método instrumental (3,7 vs.
5,9 e 6,9 kgf, respectivamente). Sendo que na avaliação sensorial para o
atributo dureza, a carne dos animais ANCR, ANHH e HHHH foi considerada
mais macia que de animais NENE. A raça Caracu pode ser usada com
alternativa ao zebu no cruzamento com raças britânicas apresentando níveis
comparáveis quanto aos aspectos quantitativos da carcaça, mas com maior
maciez da carne quando comparada com raças zebuínas. O genótipo NENE
puro nas condições deste experimento apresentou baixa produtividade e
também baixa qualidade de carne e carcaça, no entanto, teve desempenho
superior no cruzamento com a raça Aberdeen Angus.
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