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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Simulação da transferência de calor e das tensões residuais térmicas obtidas em estudos de têmpera / Simulation of heat transfer and thermal residual stresses obtained in quenching studies

Renata Neves Penha 05 May 2006 (has links)
A simulação no tratamento térmico tem-se tornado de vital importância, principalmente na fase de projeto de produto e planejamento e controle produção, reduzindo significativamente o tempo e o custo antes dedicados a estas tarefas. Esta tecnologia quando combinada à medição das curvas de resfriamento, torna-se uma poderosa e confiável ferramenta para a predição das propriedades mecânicas e metalúrgicas em peças tratadas termicamente. A modelagem do processo de têmpera traz como resultados, a exeqüibilidade do processo, a constituição microestrutural final e a distribuição das distorções e tensões residuais da peça. O presente trabalho visa simular a transferência de calor, através do cálculo dos coeficientes de transferência de calor, e das tensões residuais térmicas e distorções em corpos de prova de aço AISI 5160 e de uma sonda de Inconel 600, com a análise posterior dos parâmetros obtidos. / The simulation of heat treating is becoming of vital importance, specially during design of product and production planning and control, reducing significantly costs and time that used to be wasted on these tasks. This technology when combined to measured cooling curves, become a powerful and trustful tool for predicting mechanical and metallurgical properties of heat treated components. Modeling the quenching process shows the feasibility of the process, the final microstructure and the distribution of residual stresses and distortions on workpiece. The present work aims at simulate the heat transfer, the thermal residual stresses and distortions in a workpiece of AISI 5160 steel and of a probe of Inconel 600, with posterior analysis of the obtained parameters.
22

Variações na retenção de CCA-A em estacas de Pinus após 21 anos de exposição em campo de apodrecimento. / Decreasing of cca-a retention in pinus stakes after 21 years of exposure in a field teste.

Viviane de Paula e Freitas 13 May 2002 (has links)
A durabilidade da madeira preservada quando em contato direto com o solo, é determinada, principalmente, pela concentração do preservante na madeira, usualmente definida como retenção. Dentre os diversos produtos usados na preservação da madeira, a literatura especializada é concordante ao afirmar que o CCA (arsenato de cobre cromatado) é um dos mais eficientes, com citações de durabilidade acima de 40 anos. Contudo, também é citada a perda do produto ao longo do tempo, a qual poderia comprometer sua eficiência. Assim o presente trabalho teve como objetivo quantificar a retenção atual de CCA tipo A em estacas de Pinus, após 21 anos de exposição em campo de apodrecimento, buscando relacionar o nível de retenção com a possível perda de produto e com a durabilidade da madeira. O material para ensaio foi coletado de um campo de apodrecimento com estacas (Padrão IUFRO); quantificando-se a retenção atual através da técnica de espectrofotometria de absorção atômica e comparando-se os resultados com a retenção inicial. Foi possível comprovar a perda de CCA-A na madeira tratada, a qual está diretamente relacionada com o nível de retenção inicial. Dentre oscomponentes do preservante, as maiores perdas foram observadas para o Cu, e as menores para o Cr; levando ao desbalanceamento entre os componentes do produto (CCA-A) que permanece na madeira. Todavia, a redução observada na retenção do CCA-A, até o momento, não afetou a durabilidade da madeira preservada. / The durability of treated wood in direct ground contact is mainly determined, by the concentration of preservative in wood, usually defined as retention. Among the products used to preserve wood, specialized literature aggress about CCA (chromated copper arsenate) as one of the most efficients, with citations of durability above 40 years. However, product loss along exposure time is also noticed, which could compromise its efficiency. This research has as objective, to quantify the current retention of CCA type A in Pinus stakes, after 21 years of exposure in field test, trying to relate the level of retention to the possible product loss and to wood durability . The material on trial was collected from a stake field test (IUFRO Standard); in order to quantify the current retention through spectroscopy atomic absorption technique and to compare the results with the initial retention. It was possible to prove the CCA-A loss in the treated wood, which is directly related to the level of initial retention. From individual preservative components, copper (CuO), showed the biggest loss, while chromium (CrO3) showed the lesser one. As a result, the remanaing CCA-A in the lumber turned unbalanced. However, the reduction observed in the retention of the CCA-A, until this moment, did not affect the durability of preserved wood.
23

Avaliação dos efeitos dos parâmetros de usinagem e dos tratamentos térmicos no torneamento de três aços inoxidáveis austeníticos. / Evaluation of cutting parameters and heat treatments in the turning process of three austenitic stainless steels.

Luciano de Souza 04 April 2006 (has links)
Este trabalho teve por objetivo estudar o efeito dos parâmetros de corte e dos tratamentos térmicos na usinagem de três aços inoxidáveis austeníticos (ABNT 303, 304 e 310). Estes aços apresentam mesma estrutura cristalina e microestrutura semelhante. O aço ABNT 303 tem composição próxima ao ABNT 304, exceto pelo elevado teor de enxofre. Já o aço ABNT 310 apresenta maiores teores de elementos de ligas. Esses materiais foram tratados termicamente (solubilização ou envelhecimento). Os aços estudados foram caracterizados microestruturalmente e foram realizadas medidas de dureza Vickers. Os aços foram então torneados em várias condições de usinagem, variando principalmente a relação avanço por profundidade de corte. Foram medidas as forças de corte e de avanço em algumas das condições e coletados os cavacos resultantes para análise morfológica, que foram realizadas utilizando-se principalmente microscopia óptica e eletrônica de varredura. Foram também medidas as rugosidades e determinados os perfis das superfícies usinadas para a avaliação do acabamento superficial. Os resultados obtidos neste trabalho permitiram determinar algumas diferenças no comportamento dos três aços inoxidáveis estudados. As maiores diferenças foram verificadas quando as superfícies foram observadas utilizando microscopia. O aço ABNT 303 apresentou as piores superfícies e os menores esforços de corte em relação aos aços ABNT 304 e 310. A utilização de diferentes ferramentas neste trabalho mostrou influência principalmente na formação do cavaco, não tendo muita influencia nos esforços de corte e tão pouco no acabamento superficial. Os tratamentos térmicos realizados propiciaram a formação de outras fases, as quais causaram alterações na microestrutura. No entanto, esses tratamentos térmicos não alteraram de forma significativa o processo de torneamento. Finalmente, a formação de martensitas induzidas por deformação foi identificada no cavaco, mas não pode ser quantificada. / The main objective of this work is to study and evaluate the effect of cutting parameters, the cutting tool and the heat treatments in the turning process of three different types of austenitic stainless steels (ABNT 303, 304 e 310). The steels studied are structurally and microstructurally comparable. The chemical composition of the ABNT 303 and the ABNT 304 is similar except for the presence of sulfur in the ABNT 303 steel which alloeds the manganese sulfide formation. On the other hand, the ABNT 310 steel is richer in alloying elements and has lower tendency to strain induced martensite formation than the other steels studied. The steels studied were also heat treated in different conditions (annealed and aged). The materials were microstructurally characterized and Vickers hardness was also measured. The turning tests were carried out by using different cutting parameters, mainly the feedcutting depth relations. These relations lead to a plane state of tension or a plane state of deformation. The cutting and feed forces were measured during turning tests. During the tests the chips were also collected for morphological analysis through optical and scanning electron microscopies. The roughness and the surfaces characteristics were also determined to evaluate the surface finishing. The major difference in the steels turned was related to surface finishing observed by using optical and scanning electron microscopies. On the whole, the ABNT 303 steel presented the worst surface and the lowest cutting forces. However, the differences among all results were not significant. The tests carried out also showed there was not considerable difference between the tools used except for the chip morphology. The heat treatments led to precipitation in the steels studied and changes in their microstructure. However, the microstructural changes hardly affected the results of the turning tests. Finally, the martensite formation was detected although this phase could be not quantified.
24

Avaliação dos efeitos dos parâmetros de usinagem e dos tratamentos térmicos no torneamento de três aços inoxidáveis austeníticos. / Evaluation of cutting parameters and heat treatments in the turning process of three austenitic stainless steels.

Souza, Luciano de 04 April 2006 (has links)
Este trabalho teve por objetivo estudar o efeito dos parâmetros de corte e dos tratamentos térmicos na usinagem de três aços inoxidáveis austeníticos (ABNT 303, 304 e 310). Estes aços apresentam mesma estrutura cristalina e microestrutura semelhante. O aço ABNT 303 tem composição próxima ao ABNT 304, exceto pelo elevado teor de enxofre. Já o aço ABNT 310 apresenta maiores teores de elementos de ligas. Esses materiais foram tratados termicamente (solubilização ou envelhecimento). Os aços estudados foram caracterizados microestruturalmente e foram realizadas medidas de dureza Vickers. Os aços foram então torneados em várias condições de usinagem, variando principalmente a relação avanço por profundidade de corte. Foram medidas as forças de corte e de avanço em algumas das condições e coletados os cavacos resultantes para análise morfológica, que foram realizadas utilizando-se principalmente microscopia óptica e eletrônica de varredura. Foram também medidas as rugosidades e determinados os perfis das superfícies usinadas para a avaliação do acabamento superficial. Os resultados obtidos neste trabalho permitiram determinar algumas diferenças no comportamento dos três aços inoxidáveis estudados. As maiores diferenças foram verificadas quando as superfícies foram observadas utilizando microscopia. O aço ABNT 303 apresentou as piores superfícies e os menores esforços de corte em relação aos aços ABNT 304 e 310. A utilização de diferentes ferramentas neste trabalho mostrou influência principalmente na formação do cavaco, não tendo muita influencia nos esforços de corte e tão pouco no acabamento superficial. Os tratamentos térmicos realizados propiciaram a formação de outras fases, as quais causaram alterações na microestrutura. No entanto, esses tratamentos térmicos não alteraram de forma significativa o processo de torneamento. Finalmente, a formação de martensitas induzidas por deformação foi identificada no cavaco, mas não pode ser quantificada. / The main objective of this work is to study and evaluate the effect of cutting parameters, the cutting tool and the heat treatments in the turning process of three different types of austenitic stainless steels (ABNT 303, 304 e 310). The steels studied are structurally and microstructurally comparable. The chemical composition of the ABNT 303 and the ABNT 304 is similar except for the presence of sulfur in the ABNT 303 steel which alloeds the manganese sulfide formation. On the other hand, the ABNT 310 steel is richer in alloying elements and has lower tendency to strain induced martensite formation than the other steels studied. The steels studied were also heat treated in different conditions (annealed and aged). The materials were microstructurally characterized and Vickers hardness was also measured. The turning tests were carried out by using different cutting parameters, mainly the feedcutting depth relations. These relations lead to a plane state of tension or a plane state of deformation. The cutting and feed forces were measured during turning tests. During the tests the chips were also collected for morphological analysis through optical and scanning electron microscopies. The roughness and the surfaces characteristics were also determined to evaluate the surface finishing. The major difference in the steels turned was related to surface finishing observed by using optical and scanning electron microscopies. On the whole, the ABNT 303 steel presented the worst surface and the lowest cutting forces. However, the differences among all results were not significant. The tests carried out also showed there was not considerable difference between the tools used except for the chip morphology. The heat treatments led to precipitation in the steels studied and changes in their microstructure. However, the microstructural changes hardly affected the results of the turning tests. Finally, the martensite formation was detected although this phase could be not quantified.
25

Characterization of Aluminum 3003 Ultrasonic Additive Manufacturing

Schick, David E. January 2009 (has links)
No description available.
26

The Use of Music as a Therapeutic Agent in Connection with and as an Aid to Hospitalized Mental Patients

McClung, Marjorie C. (Marjorie Catherine) 01 1900 (has links)
The increasing importance of music as a therapeutic benefit in mental hospitals has prompted this study. Numerous unscientific reports and papers concerned with music therapy have been published; however, material based upon controlled experiments and results is available which has proven valuable in the study of this growing aid for mental patients. The reference material in the following chapters has been organized and limited to objective reports produced by those who have devoted their interest and time to the facts about the use of music as a therapeutic agent in mental hospitals.
27

A COST - COMPARISON OF THE USE OF INFLUENZA VACCINE IN OLD AGE HOME RESIDENTS IN JOHANNESBURG

Cobb, Hugh 17 November 2006 (has links)
M Family Medicine research report - Faculty of Health Sciences / Residents of old age homes are at increased risk for the complications of influenza. Studies in developed countries have consistently shown that influenza vaccination of old age home residents and staff can significantly decrease morbidity and mortality rates and that influenza vaccination is one of the most cost effective interventions possible in this population. No studies have been done on the cost benefit of using influenza vaccine in old age home residents in South Africa. The aim of this study was to evaluate the costs of treating influenza and influenza-like illnesses in old age home residents, and to compare the costs in people who had received the influenza vaccine to those who had not. The study population comprised 151 people residing in two old age homes in Johannesburg, namely Sandringham Gardens and Nazareth House. The study population was divided into two groups- those who received influenza vaccine and those who had not been vaccinated. The residents of Nazareth House who gave consent had all been vaccinated. The subjects at Sandringham Gardens were sub- divided into two groups, namely: “Residents” and “Frail care / wards” section. The general health of the “Frail care” people was poorer than that of the “residents”. Medical records were reviewed, and details of the number of doctor consultations, medication and physiotherapy prescribed, special investigations performed and hospital referrals related to influenza and influenza-like infections were recorded. The costs were then calculated using “medical aid rates”. There were no significant differences in the treatment costs, comparing those who had been vaccinated to those who had not been vaccinated. There are a number of possible explanations for this. These include, most importantly, a low to moderate epidemic activity of influenza in the season that the study was conducted. Other explanations are low patient numbers, the use of symptoms for diagnosis and the use of over the counter therapy. Despite the findings in the present study, the international literature supports the view that influenza vaccination is a cost-effective intervention in the older adult population, particularly those at higher risk. These findings have been implemented in the official guidelines of many countries, including the South African Adult Influenza Vaccination Guideline.
28

"De ska känna att de är huvudpersonen i sitt eget liv". : En kvalitativ studie om hur personal inom familjebehandlande HVB-hem upplever brukarinflytande. / "They are supposed to feel like the main person in their own life". : A qualitative study about how professionals within family-treating residential care experiences user influence.

Gotvik, Jonna, Jansson, Johanna January 2018 (has links)
The aim of this study was to gain knowledge about how professionals experience user influence within family-treating residential care. To collect empiricism for this study semi structed interviewes was conducted with eight employees within family-treating residential care. These interviews were later processed through a content analysis, it becomes clear that the participants acknowledged the importance of user influence within its own treatment. Further on, the result has been analysed by the theory called empowerment and previous research within the current subject, ”user influence within family-threating residential care”. However, the result of this study is that the user influence should always exist though in certain circumstances it should be limited.
29

Incrustamento em sementes de azevém anual(Lolium multiflorum lam.): características físicas e qualidade fisiológica / Ryegrass (Lolium multiflorum Lam.) seed incrusting: physical characteristics and physiological quality of seeds

Peres, Wilner Brod 27 August 2010 (has links)
Made available in DSpace on 2014-08-20T13:44:49Z (GMT). No. of bitstreams: 1 tese_wilner_brod_peres.pdf: 612357 bytes, checksum: 59492c2356959cbf155603f521184e13 (MD5) Previous issue date: 2010-08-27 / The objective of the present research was to increase ryegrass seed weight thought addition of inert materials by the process of incrusting (seed weight increase without change its form), to reduce drifting and to uniform its distribution improving it ballistic power when sowed by airplane. Two seed lots were used harvested in 2007/2008. After air separation to remove light materials and impurities, seeds were screened through two oblong holes screens: 1,2 x 20 mm and 0,8 x 12 mm, being used seeds over the 0,8 x 12 mm screen. Seeds were treated with insecticide Standak®, fungicide Vitavax® - Thiram 200 SC and Giberellic acid ProGibb® (10%). Inert materials used were Vermiculite and natural Phosphate of ARAD grinded and passed by nº 100 screen. Adhesive materials were used Rigrantec polymers Polyseed 70® and Polyseed CF® diluted in water in proportion of 1:1. Those materials were added to the seeds in four individual layers including a drying period among each layer. The physical characteristics of seeds were determined by 1000 seeds weight, test weight, repose angle and terminal velocity. The physiological quality of the seeds was evaluated by the following tests: standard germination, first count of germination, accelerated ageing, speed of emergence, emergence speed index, aerial part length, root length and dry matter weight. Seed moisture content was also determined before and after the accelerated ageing test. Results allowed the following conclusions: Incrusting ryegrass seeds increase seed weight in 6.1 times, improving airplane sowing conditions. Physical characteristics of incrusted ryegrass seeds are favorable to airplane sowing due to improve repose angle, test weight and terminal velocity of seeds. Physiological quality of ryegrass seeds is not affected by the incrusting technique using adhesive materials, polymer, fungicide, insecticide and Gyberellic Acid. Ryegrass seedling performance is improved by incrusting of seeds with adhesive materials, polymer, fungicide, insecticide and Gyberellic Acid. Incrusted seeds have better control of moisture absorption by seeds. / - O objetivo do presente trabalho foi incrementar o peso das sementes de azevém através da adição de materiais inertes pelo processo de incrustamento (aumentar o peso das sementes sem, no entanto, alterar sua forma), buscando diminuir a deriva e uniformizar sua faixa de distribuição, melhorando seu poder balístico quando semeadas por meio de aeronaves agrícolas. Foram utilizados dois lotes de sementes colhidas na safra 2007/2008. Após a passagem das sementes por uma coluna de ar para retirada de impurezas, estas foram classificadas em duas peneiras de furos oblongos 1,2 x 20 mm e 0,8 x 12 mm, sendo utilizadas somente as sementes retidas na peneira 0,8 x 12 mm. As sementes foram tratadas com inseticida Standak®, fungicida Vitavax® - Thiram 200 SC e Ácido Giberélico ProGibb® (10%). Como materiais inertes foram utilizados Vermiculita e Fosfato natural de ARAD moídos e passados em peneiras nº 100, e como materiais adesivos foram utilizados os polímeros Rigrantec Polyseed 70® para agregar os materiais inertes e Polyseed CF® para conferir resistência e acabamento ao incrustamento, diluídos em água na proporção de 1:1. Estes materiais foram agregados às sementes em quatro camadas individuais com um período de secagem entre cada uma das camadas. As características físicas das sementes foram determinadas pelo peso de mil sementes, peso volumétrico, ângulo de repouso e velocidade terminal experimental. A qualidade fisiológica das sementes foi avaliada pelos testes: germinação, primeira contagem de germinação, envelhecimento acelerado, velocidade de emergência, índice de velocidade de emergência, comprimento da parte aérea, comprimento da raiz, peso de matéria seca. Também foi determinado o teor de água das sementes antes e após o envelhecimento acelerado. Os resultados permitiram concluir que: O incrustamento de sementes de azevém aumenta o peso das sementes em 6,1 vezes, melhorando as condições de semeadura aérea. As características físicas das sementes de azevém incrustadas são favoráveis à semeadura aérea ao melhorar o ângulo de repouso, o peso volumétrico e a velocidade terminal das sementes. A qualidade fisiológica das sementes de azevém não é afetada pela técnica do incrustamento com materiais adesivos, polímero, fungicida, inseticida e ácido giberélico. O desempenho das plântulas de azevém é melhorado pela técnica de incrustamento das sementes com materiais adesivos, polímero, fungicida, inseticida e ácido giberélico. As sementes incrustadas têm melhor controle da absorção de umidade nas sementes.
30

Odstraňování plynných polutantů ze vzdušnin na poloprovozní pračce / Removing of Gaseous Pollutants from the Air Masses on the Pilot-Plant Scrubber

Kalivoda, Josef January 2017 (has links)
The PHD thesis is focused on the absorption with chemical reaction on the pilot plant gas/liquid scrubber. The performance characterization of the apparatus is based on the absorption of carbon dioxide in to the 1\% sodium hydroxide sollution and includes pressure drops, liquid holdup, gas/liquid contact time and the capture effectiveness as well. The experimantal part of the thesis includes a complex of mathematical equations based on the Film theory. The complex of the mathematical equations allowed a calculation of the overall mass transfer coefficient for the type of the gas scrubber at the given experimental conditions.

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