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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.
201

Effects of porcine circovirus type 2 vaccination, biofuel co-products, and dietary enzymes on finishing pig performance under field conditions

Jacela, Jay Yanoria January 1900 (has links)
Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Joel M. DeRouchey / Steven S. Dritz / A total of 9,979 pigs were used in 11 experiments to quantify production responses under field conditions in growing pigs to PCV2 vaccination, biofuel co-products and dietary supplemental enzymes. Experiments 1 and 2 were conducted to determine the efficacy of a commercial 2-dose Porcine Circovirus Type 2 (PCV2) vaccine. Growth performance and mortality (P < 0.05) of vaccinated pigs improved compared to non-vaccinated pigs in both experiments with the vaccine causing a greater increase in ADG in vaccinated barrows than vaccinated gilts in Exp. 2. Experiment 3 compared the efficacy of 1-dose and 2-dose commercial PCV2 vaccines, where vaccinated pigs had greater ADG (P < 0.05) than vaccinated pigs regardless of vaccine type. The 2-dose group was heavier (P < 0.05) than the control group while the 1-dose group was intermediate. Therefore, PCV2 vaccines were efficacious under field conditions. Experiments 4, 5, and 6 were conducted to evaluate de-oiled corn dried distillers grains with solubles (dDGS) in grow-finish pigs. In Exp. 4, analyzed CP and AA content were higher, but lysine digestibility and energy content were lower in dDGS than traditional dried distillers grains with solubles (DDGS). In Exp. 5, 0 to 30% dDGS in nursery diets did not affect growth performance (P > 0.52). In Exp. 6, 0 to 30% dDGS reduced (linear; P < 0.01) ADG and ADFI, tended to improve (linear; P > 0.07) G:F, decreased (linear; P < 0.01) carcass yield, and increased (linear; P < 0.01) fat iodine values. Experiment 7 was conducted to determine the AA digestibility and energy concentration of novel high-CP distillers co-products from corn (HPC-DDG) and sorghum (HPS-DDGS). Digestibility of AA was higher for HPC-DDG but lower in HPS-DDGS than traditional DDGS. Both co-products had lower energy than traditional DDGS. Finally, Exp. 8, 9, 10, and 11 were used in a meta-analysis to evaluate supplementary dietary enzymes in pigs. Supplemental enzymes, alone or in combination, did not improve grow-finish pig performance (P > 0.58) regardless of dietary DDGS level. In conclusion, these experiments provide important empirical data to quantify production responses of various interventions and dietary ingredients under actual field conditions.
202

Industrial waste minimisation in South Africa : a case study in the textile and metal finishing sectors.

Reiner, Monika. January 2002 (has links)
Environmental legislation is becoming more stringent as people are realising the need for conservation and a reduction of environmental degradation in order to facilitate sustainable development. To ease legislative pressures, companies need to work together in symbiotic networks, whereby co-operation between companies results in far more innovative practices than if the companies acted individually. Success in an industrial network is largely dependent on cleaner production, where industries seek to redirect from waste treatment to waste minimisation. Cleaner production has already received international recognition and waste minimisation initiatives have been used as a tool of cleaner production. Two polluting industrial sectors within South Africa, the textile and metal finishing sectors, were chosen to investigate waste minimisation concepts. One company from each sector was used as a case study. The dissertation followed company network identification, potential to participate within an industrial symbiotic network, and waste minimisation opportunities. Suppliers and buyers, up and down the product line were identified. Relationships with these partners should be advanced such that environmental concerns are at the forefront of any decision-making. In light of developing industrial networks and maintaining symbiotic relationships, the company's potential was investigated by interviewing employees of various ranks. Both companies were partially suited to participate within an industrial symbiotic network and company-specific barriers were identified, such as ineffective internal communication. The waste minimisation investigation followed a four-phase approach of planning and organisation; pre-assessment; assessment; and feasibility study. In both the companies investigated, water savings were identified as the waste minimisation focus area with potential for improvement. In total, potential water savings of over R80 000 per annum were identified. In the textile company, the weaving department and bleach house were further investigated. Cloth weaving errors were attributed to machine stops, as each stop has the potential to result in a cloth fault. In the bleach house the potential existed to reduce the number of rinse tanks. Although a modem and automated process, the plating plant in the metal finishing company was identified as having potential waste minimisation opportunities. Of particular interest was the reduction of solution carry over from the plating tanks into subsequent tanks. Extended drip times were investigated. Additional waste minimisation opportunities included repairing pipe leaks, replacing the degreasing solvent, trichloroethylene, with a less harmful cleaning agent and establishing a symbiotic relationship with the oil supplier, Castrol. Over and above the main waste minimisation opportunities highlighted, other recommendations and potential savings were identified. Each case study emphasises that simple waste minimisation initiatives, without expending capital, reduce demands on natural resource, such as water, and benefit the company financially. Successful waste minimisation leads to further cleaner production initiatives, which may then initiate better network interactions with the further potential of promoting sustainable development. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2002.
203

Fuktproblem i putsade fasader : Enstegstätade ytterväggar utsatta för slagregn

Tell, Emma, Jansson, Oskar January 2016 (has links)
One purpose of this work was to examine if a modification of the exterior insulation finishing system can lower the number of outer walls damaged by damp. The modification is the cut of the cellular plastic which is 45 degrees instead of a horizontal cut. One other purpose was; is cellular plastic or mineral wool better as insulation to minimize the dampness in this type of outer walls? A third purpose was to examine if there is any difference of dampness in the outer walls if using a gravel bed or concrete stones next to the outer wall. To examine these three purposes a laboratory experiment with three test walls with an exterior insulation finishing system was built. The difference between the three walls was the insulation. One wall was built with mineral wool with a horizontal cut, one with cellular plastic with a horizontal cut and the third with cellular plastic with a cut of 45 degrees. Simulations of pelting rain and measurements of dampness were carried out for 21 days. The measurements were taken at the same time every evening. After 21 days small samples of tree from the walls was weight, dried in an oven and then weight again to get the quantity of moisture in the samples before they were dried. A diffusion calculation of two outer walls, one with cellular plastic and one with mineral wool, was completed to examine the difference between the relative humidity in the walls. An identical calculation without a plastic film was executed too. The result of the calculations showed a minimal difference in the walls built with a plastic film. When the film was removed the result presented critical values. The result of the laboratory experiment indicates that the test wall with the cut of 45 degrees is better than the walls with a horizontal cut of the insulation. The differences were minimal but possible to read. Some critical, too high, values regarding the moisture content in wood were found and they came from the sills in the walls that had insulation with horizontal cuts. Of the two insulation types the result of calculations and laboratory experiment shows a minimal difference but they both indicates a better result for the mineral wool. The conclusion of this work indicates that cellular plastic with a 45 degree cut is slightly better than the horizontal cut. The comparison of cellular plastic and mineral wool indicates that the mineral wool is better. Another conclusion of this work is that the material on the ground next to the outer wall did not alter the dampness in the wall.
204

An application of reverse osmosis process on effluent treatment for the rubber industry

Ralengole, Galebone 05 1900 (has links)
M. Tech., (Chemical Engineering, Department of Chemical Engineering, Faculty of Engineering and Technology Vaal University of Technology| / The methods used to remove potassium sulphate (K2S04) and other impurities contained within Karbochem finishing plant effluent were investigated. Reverse osmosis was explored for this application. The study was conducted in two steps. The first step focuses mainly on the effluent treatment using BW30 flatsheet as well as BW30-2540 spiral-wound reverse osmosis membranes for the rejection of potassium and sulphate ions. The membranes were supplied by Filmtec. The second step reveals the possible use of potassium sulphate obtained from the brine stream in the fertiliser and fertigation industry by a literature search. Reverse osmosis study was conducted on a laboratory scale unit using flat sheet membranes and also on a pilot plant scale using spiral wound membrane modules. The tests were conducted at a feed pressure of 20 bar(g) with the membrane rejections being 98% and 99.1% on flat sheet membrane, and 96.9% and 99.4% on spiral wound membrane for potassium and sulphates respectively. The results show that both membranes have completely desalinated. Significant reduction in the concentrations of all problematic quality parameters, especially of potassium and the sulphate ions was noted. Granular activated carbon (GAC) bed treatment was recommended for pretreatment of the effluent prior to exposure of the membrane to avoid organic fouling of the membrane. GAC treatment was tested to illustrate its effectiveness to adsorb the COD's. / NRF
205

Protocolos de adaptação à dietas com alta inclusão de concentrados para bovinos nelore confinados /

Parra, Fernando Salvador, 1982- January 2011 (has links)
Orientador: Mário de Beni Arrigoni / Banca: Rafael da Costa Cervieri / Banca: Paulo Henrique Mazza Rodrigues / Resumo: O objetivo deste estudo foi avaliar os efeitos de protocolos de adaptação à dietas com alta inclusão de concentrados sobre o desempenho, seletividade dos ingredientes da dieta e características de carcaça de bovinos Nelore terminados em confinamento. Cento e vinte bovinos, machos não castrados com peso médio inicial (PI) de 372,19 ± 21,46 kg, provenientes de sistema de recria em pasto, foram mantidos por 84 dias em 24 baias de piso de concreto (5 animais/baia), de acordo com os tratamentos: protocolo de escadas por 14 dias (S14), protocolo de escadas por 21 dias (S21), protocolo de restrição por 14 dias (R14) e protocolo de restrição por 21 dias (R21), constituindo-se assim delineamento experimental em blocos casualizados, em arranjo fatorial 2 × 2 (protocolo escada ou restrição e duração de 14 ou 21 dias), com 6 repetições/tratamento, distribuídas em 6 blocos. Nenhuma diferença foi encontrada (P>0,10) para PI, peso final, ganho de peso diário, ingestão de matéria seca em quilos, conversão alimentar e eficiência alimentar com relação ao efeito de protocolos de adaptação. Houve interação (P<0,05) entre protocolo e duração, onde S21 proporcionou maior ingestão de matéria seca em porcentagem do peso vivo em relação a R21 (2,43 vs. 2,34). Nos 2 primeiros dias do período de terminação, os animais submetidos aos protocolos com duração de 14 dias selecionaram a favor de partículas maiores. O protocolo de restrição proporcionou maior (P=0,10) espessura de gordura subcutânea em comparação ao protocolo de escadas. Não houve diferença (P>0,10) para gordura visceral em quilos, gordura visceral em porcentagem da carcaça quente e custo por quilo de peso vivo. O peso de carcaça quente e o rendimento de carcaça foram maiores (P<0,05) para a duração de 14 dias, comparado à duração de 21 dias (285,61 vs. 278,72 e 56,76 vs. 56,13). A adaptação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study, conducted at the São Paulo State University feedlot, Botucatu Campus, Brazil, was designed to determine effects of restricting intake of the final finishing diet (REST) as a means of dietary adaptation compared to diets increasing in concentrate (STEPUP) over periods of 14-d or 21-d on overall feedlot performance, selectivity of the dietary ingredients and carcass characteristics. The experiment was designed as a completely randomized block with a 2 x 2 factorial arrangement, replicated 6 times (5 bullocks/pen), in which 120 18-mo-old yearling Nellore bulls (372.2 ± 21.5 kg) were fed in 24 pens for 84-d according to the treatments: STEPUP for 14-d, STEPUP for 21-d, REST for 14-d, and REST for 21-d. The STEPUP program consisted of ad libitum feeding of three adaptation diets over periods of 14-d or 21-d with concentrate level increasing from 55% to 85% of diet DM. The REST program consisted of restricted intake of the final diet (85% concentrate) with programmed increases in feed offered until yearling bulls reached ad libitum access over periods of 14-d or 21-d. No significant (P > 0.10) protocols and days main effects were observed for any of the feedlot performance parameters analyzed: initial and final BW, ADG in kg, F:G ratio, G:F ratio and DMI in kg, however a interaction was found (P < 0.05) for DMI in % of BW. Animals in STEPUP for 21-d treatment presented greater DMI (% of BW) than yearling bulls in REST for 21-d (2.43% vs. 2.34%). Animals in REST treatment had greater (P=0.10) 12th rib fat thickness than the STEPUP. With respect to carcass characteristics, no significant (P > 0.10) protocols and days main effects were observed for kidney-pelvic fat, kidney-pelvic fat in HCW percentage and cost of gain, however, yearling bulls in treatments that lasted 14-d presented heavier (P < 0.05) HCW (285.61 kg vs. 278.72 kg) and increased (P < 0.05) dressing percentage... (Complete abstract click electronic access below) / Mestre
206

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.

Nunes, Eduardo 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.
207

Soldabilidade metalúrgica do aço ASTM A553 tipo I com 9% de ní­quel. / Metallurgical weldability of ASTM A553 Type I steel with 9% nickel.

Jaime Casanova Soeiro Junior 06 December 2017 (has links)
A soldagem altera as propriedades mecânicas dos aços ligados ao níquel, em especial seu desempenho em aplicações criogênicas. Assim, este trabalho apresenta um estudo sobre a soldabilidade metalúrgica do aço com 9% níquel e tem como objetivos: identificar se a fragilização em temperatura abaixo da temperatura Ac3 ocorre em ZACs com dois e três ciclos térmicos simulados fisicamente; analisar as características da junta soldada pelo processo de soldagem por atrito linear com mistura e os efeitos da soldagem multipasse; e analisar a influência dos passes de enchimento e acabamento sobre o comportamento mecânico da ZAC da raiz de uma junta soldada pelo processo de soldagem MIG/MAG. Destacam-se entre os resultados da simulação física da ZAC: as amostras que tiveram a temperatura máxima abaixo da temperatura Ac1, no terceiro ciclo térmico, não apresentaram o efeito de redução da energia absorvida no ensaio Charpy V; a fração volumétrica de austenita retida não aumenta a quantidade de energia absorvida no ensaio Charpy V para as amostras que tiveram a temperatura máxima do segundo ciclo térmico abaixo da temperatura Ac3 (723°C); e a correlação linear múltipla sugere um modelo empírico, baseado nos dados deste trabalho, onde os fatores de fração volumétrica do microconstituinte martensita-austenita, fração volumétrica de austenita retida e tamanho de grão são mais relevantes para a quantidade de energia absorvida no ensaio Charpy V. Destacam-se entre os resultados da soldagem por atrito linear: a energia absorvida no ensaio Charpy V da zona misturada do primeiro cordão (CP1) é menor que o metal de base; o segundo cordão gera duas regiões na zona misturada do primeiro cordão, que tendem a aumentar a energia absorvida no ensaio Charpy V; os valores de energia absorvida no ensaio Charpy V apresentam correlações lineares simples com a microdureza, a fração volumétrica do microconstituinte martensita-austenita e com o tamanho de grão. Destacam-se entre os resultados da soldagem com MIG/MAG: A soldagem do aço com 9% de níquel com a liga Inconel 625 gera uma zona não misturada entre o metal de solda e a ZAC; a amostra com todos os passes de solda (CP3) apresenta a menor energia absorvida no ensaio Charpy V entre todos os experimentos; e a trinca, no ensaio Charpy V, propaga na zona não misturada no CP1 e no CP2, que tiveram as maiores energias absorvidas no ensaio Charpy. O CP3 apresenta propagação de trinca na linha de fusão e possui a menor energia absorvida no ensaio Charpy V. / Welding modify the mechanical properties of nickel steels, especially their performance in cryogenic applications. Thus, this work presents a study on the metallurgical weldability of 9% nickel steel and its objectives are: identify if the embrittlement in temperature below the Ac3 temperature occurs in HAZs with two and three thermal cycles simulated physically; analyze the characteristics of the joint welded by friction stir welding process and the effects of multipass welding; and analyze the influence of the filling and finishing passes on the mechanical behavior of HAZ from the root of a joint welded by the GMAW welding process. The results of the physical simulation of the HAZ were: the samples that had the maximum temperature below the temperature Ac1, in the third thermal cycle, did not present the effect of reduction of the energy absorbed in the Charpy V test; the retained austenite volumetric fraction does not increase the amount of energy absorbed in the Charpy V test for the samples having the maximum temperature of the second thermal cycle below the Ac3 temperature (723 °C); and the multiple linear correlation suggests an empirical model, based on the data of this work, where the volumetric fraction factors of the martensite-austenite microconstituent, retained austenite volumetric fraction and grain size are more relevant for the amount of energy absorbed in the Charpy V test. The FSW welding highlights results: the energy absorbed in the Charpy V test of the mixed zone of the first pass (CP1) is smaller than the base metal; the second pass generates two regions in the mixed zone of the first pass, which tend to increase the energy absorbed in the Charpy V test; the values of energy absorbed in the Charpy V test show simple linear correlations with the microhardness, the volumetric fraction of the martensite-austenite microconstituent and with the grain size. The GMAW welding highlights results: welding of the steel with 9% nickel with the Inconel 625 alloy makes an unmixed zone between the weld metal and the HAZ; the sample with all weld passes (CP3) shows the lowest energy absorbed in the Charpy V test among all the experiments; and the crack, in the Charpy V test, propagates in the unmixed zone in CP1 and CP2, which had the highest energies absorbed in the Charpy test. The CP3 shows crack propagation in the melting line and has the lowest energy absorbed in the Charpy V test.
208

Características de carcaças bovinas obtidas por frigoríficos na região central do Brasil, um retrato espacial e temporal / Beef carcass characteristics from meat industries in the central region of Brazil, a spatial and temporal picture

Soria, Rafael Ferreira 30 September 2005 (has links)
As características de carcaças bovinas relacionam-se indiretamente com aspectos de qualidade da carne bovina, bem como permitem verificar limitações e progressos do sistema produtivo. Portanto, um retrato atual daquelas características em âmbito regional e suas variações anuais e plurianuais é ferramenta essencial na transferência de informação para o gerenciamento e sustentabilidade da cadeia de carne bovina. A análise do banco de dados de um grupo frigorífico com unidades industriais localizadas no Sudoeste de Mato Grosso do Sul, Meio-Oeste de São Paulo, Noroeste de Goiás e Triângulo Mineiro, importantes regiões para a pecuária nacional, durante 31 meses de operação industrial (janeiro de 2001 a agosto de 2003), permitiu descrever as características das carcaças bovinas nessas regiões geográficas, entre épocas do ano e entre os anos. Cada unidade foi abastecida principalmente por fornecedores do próprio estado e as regiões que mais negociaram estavam nas proximidades das unidades, exceto a unidade frigorífica de SP onde grande parte do abate teve origem no Leste de MS. As fêmeas totalizaram 13,16% dos abates e houve oferta crescente no período a partir do segundo semestre de 2002 com pequena redução no abate de machos, destes 75,96% eram castrados e 10,88% inteiros. A região teve impacto na oferta de características como classe sexual, maturidade e grau de acabamento para machos castrados, contudo houve um padrão predominante em todas as unidades em volume e freqüência de oferta, com carcaças de machos castrados de 6 a 8 dentes compondo 61,6% dos abates do grupo. A unidade de GO foi a que mais abateu machos inteiros, totalizando 36% dos abates. A unidade de MG se destacou na proporção de machos castrados até 4 dentes (novilhos) em relação aos machos castrados abatidos, com uma média de 25%. O abate de novilhos com grau de acabamento 3 (espessura de gordura entre 3 e 6 mm) representaram 7,9% dos abates, destacando-se MS e SP em volume de abate e proporção, com 2/3 dos novilhos atingindo este acabamento. A oferta de carcaças de novilhos e de novilhos com grau de acabamento 3 ocorreu em dois momentos do ano, de abril a junho e de agosto a novembro. No período estudado, a oferta de novilhos com grau de acabamento 3 não acompanhou a oferta de novilhos, variando com a região, sendo que a unidade de SP foi abastecida de forma mais regular. O peso médio de abate dos machos castrados foi de 264,4 kg (DP ± 15,2 kg), equivalente a 17,6@ e à medida que os animais avançaram na idade aumentou a freqüência de carcaças pesadas. Carcaças acima de 18@ corresponderam à 40,6% dos adultos e 22,9% dos novilhos. Para os novilhos com acabamento 3 a faixa de peso predominante foi de 16 -17@ em todas unidades, exceto em MG onde a classe de peso predominante esteve acima de 18@. / Beef carcass characteristics are indirectly related with meat quality and helps to identify limitations and progresses of the productive system. Wherefore establishing a picture of such characteristics and their annual and pluriannual variations represents an essential tool on information transference for the beef supply chain management and sustainability. This study was based on data from a beef industry composed by four unities located in important Brazilian regions for beef cattle production (Southeast of Mato Grosso do Sul State, Middle-West of São Paulo State, Northwest of Goiás State and at Triângulo Mineiro Region of Minas Gerais State), during 31 months (January, 2001 to August, 2003). Database analysis allowed to describe beef carcass characteristics within periods over a year and among years of industrial activity. Producers from regions close to the plants inside the same state were their main suppliers, except for the unity in the São Paulo State where a large number of animals came from East of Mato Grosso do Sul State. Castrated males represented 75.96% of total slaughter, intact males 10.88% and females 13.16%. The number of female slaughtered increased over the second semester of 2002 reducing thus the proportion of male slaughtered. There was an influence of the supplying region on sexual condition, maturity and finishing of castrated males with up to four permanent incisors (steers). However, the main carcass pattern in all unities, when considering number and frequency, was castrated males with at least six permanent incisors, representing 61.6% of total slaughter. The Goiás State’s plant slaughtered the highest number of intact males with 36% of its total slaughter. The Minas Gerais State’s plant registered the highest proportion of steers when considering castrated male slaughtered, averaging 25% of its total. Steers with finishing grade 3 (fat thickness 3 to 6 mm) represented 7.9% of all carcasses, distinguishing Mato Grosso do Sul and São Paulo States’ plants in which two-thirds of steers reached that finishing grade. The supply of steers finishing grade 3 had two peaks with increasing offer over the years, from April to July and from August to November. The number of these carcasses did not follow steers supply with a regional influence. São Paulo State plant was the only one regularly supplied with properly finished steers. The average carcass weight was 264.4 kg (SE ± 15.2 kg). Heavier carcasses were obtained only when animals slaughtered grew older with frequencies of carcass weight over 269.9 kg corresponding to 40.6% of the older castrated males and 22.9% of the steers. The most frequent carcass weight ranged from 240 to 254.9 kg for steers with finishing grade 3 in all plants, except for the one at Minas Gerais State where the predominant weight range was over 269.9 kg.
209

Estudo dos parâmetros: teor de NaCl e acabamento superficial, na resistência à corrosão localizada e generalizada em tubos de cobre / Study of the parameters: NaCl concentration and surface finish on the pitting corrosion resistance of copper tubes

Jesus, Antonio Carlos Neto de 17 March 2008 (has links)
Tubos de cobre fabricados com o material ASTM C12200 (99,9%Cu-0,015-0,040%P) são utilizados mundialmente no transporte de água potável. A maior causa de vazamentos nestas tubulações é a corrosão por pite, que usualmente estão relacionadas com a qualidade da água. Estudos recentes mostraram que vazamentos em tubos de cobre usados para transporte de água de rede pública ocorreram em decorrência da corrosão por pite, o que se deu em virtude da presença do íon cloreto originado do tratamento para a desinfecção da água. Outro parâmetro que pode influenciar a corrosão por pite é a condição de acabamento interno dos tubos. Os óleos lubrificantes usados no processo de fabricação de tubos de cobre contêm carbono e este forma um filme deletério após o recozimento destes tubos. Este filme cria condições na superfície interna para a formação de pilhas de ação local. O objetivo deste trabalho é investigar se o teor de cloreto de sódio no meio aquoso, e o acabamento superficial da superfície interna de tubos de cobre utilizados comercialmente para transporte de água (ABNT/NBR-13206), têm influência na resistência à corrosão destes tubos. A resistência à corrosão foi investigada por meio de ensaios eletroquímicos em soluções naturalmente aeradas com várias concentrações de cloreto de sódio, a 25 oC. A superfície interna dos tubos foi observada, antes e após os ensaios eletroquímicos, por microscopia eletrônica de varredura (MEV). Os tipos de acabamentos superficiais estudados foram: desengraxamento, jateamento e acabamento do processo final de fabricação (sem tratamento). Foi também construído um circuito fechado para estudar o efeito do acabamento superficial na resistência à corrosão sob condições mais próximas das encontradas na prática. O efeito do tratamento de recozimento do tubo em atmosfera inerte, que causa a recristalização da microestrutura e eliminação dos resíduos de óleo lubrificante, também foi avaliado. Os resultados indicaram que o mecanismo de corrosão em soluções com teores de cloreto entre 0,06 mol L-1 e 0,12 mol L-1 correspondeu ao de ataque localizado, enquanto que para a concentração de 0,6 mol L-1 prevaleceu o ataque generalizado. Os resultados do estudo do efeito do acabamento superficial indicaram que os tratamentos que reduzem o teor de carbono na superfície são benéficos à resistência à corrosão, mas este não é o único fator que afeta a resistência à corrosão. Outras características superficiais resultantes do tratamento da superfície também devem ser consideradas. Por exemplo, embora o jateamento cause a diminuição do teor de carbono na superfície dos tubos, o aumento de rugosidade produzido por este acabamento pode resultar em uma menor resistência à corrosão. Os tratamentos superficiais que produziram superfície com maiores resistências à corrosão foram aqueles que também produziram superfícies com menores teores de carbono, a saber, desengraxe e recozimento. / Copper tubes manufactured with C12200 ASTM (99.9% Cu-0015-0040% P) are used worldwide for potable water transport. The largest number of leakages in these tubes is due to pitting, usually related to the water quality, associated to the presence of chloride ions originated from water disinfecting treatment. The literature on the effect of chloride on the corrosion of copper pipelines is controversial. The finishing of the copper tubes inner might also influence pitting corrosion. The lubricating oils used in the manufacture of copper tubes contain carbon and a deleterious film might form during annealing. The objective of this study is to investigate the effect of sodium chloride content and the inner surface finishing of copper tubes used for water transport (ABNT/NBR-13206) on their corrosion resistance. The study was carried out by electrochemical tests in naturally aerated sodium chloride solutions at various concentrations, at 25 °C. The tubes inner surface was observed previous to and after the electrochemical tests by scanning electron microscopy (SEM). The effects of the following surface finishing were investigated: degrease, sand blasting, annealing and the surface without treatment. A loop was built to simulate the operational conditions of the tubes. Results indicated that the corrosion mechanism in chloride solutions with concentrations between 0.06 mol L-1 and 0.12 mol L-1 was localized attack, whereas in the 0.6 mol L-1 solution, generalized attack was the predominant mechanism. The results the surface finishing investigation indicated that the treatments that leads to carbon content reduction are beneficial to corrosion resistance. However, other features must also be considered. For instance, although sand blasting reduces the carbon content on the tubes surface, the increase in roughness due to this treatment decreases the corrosion resistance. The surface treatments that resulted in increased corrosion resistance were those that also resulted in lower carbon levels at the surface, namely degreasing and annealing.
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Waves over Fabric : Why they appear and how to reduce them.

FRISK, ANNA January 2013 (has links)
Almedahls have for some time started to receive more customer complaints about uneven roller blind fabrics or so-called waves over fabric. The waves are a major problem for Almedahls customers since they make it hard to cut the fabric into roller blinds. The company believes that the waves appear due to different process parameters within their finishing line but the company do not yet know how or where. The thesis project strives to find an explanation to what waves over fabric are, why they appear and how they can be reduced. The documentation that Almedahls have made of the problem so far, including photographs and customer complaints reports, was examined. Orders produced from four selected grey-weaves during the last three years was examined and compared to received customer complaints and standard operations lists. No clear relationship was found and weaves with longer process lines did not seem to cause more waves to appear. However, addition of an extra colouring to the standard operations appeared to be more frequently occurring when a standard operations list had been changed.Waves over fabric were at an early stage related to the mechanical properties of the weaves as the weaves are exposed to stresses and strains during the entire production line. In Almedahls’ finishing line the web and the beam tensions and the levelling mechanisms in the stenter frames appeared to be the parameters which especially apply stresses and strains. Tensile tests were performed to examine the mechanical properties of a few of Almedahls grey-weaves and half processed weave. The test results showed that a strain between 11-27 % can be applied before the test samples start to deform while calculations of the amount of strain applied by the stenter frames showed to be much less, between 2.5-3.5 %. The difference in size between the test samples and the weaves must be considered when comparing these results. The small, repeated strains applied by the finishing line may eventually lead to permanent deformation of the weaves and appear as waves. The combination of the web and the beam tensions can also result in a stretch in the bias-direction of the weave which cause deformation in the middle of the weave where waves most often appear.The thermal properties of the same weaves were also tested through DSC, Differential Scanning Calorimetry, tests. The test results showed that the polyester material in the weaves does not melt or deform at the temperatures Almedahls use in their processes. The shrinkage of the grey-weaves during the de-sizing processes was also considered through width measurements. The conclusion was that the structure of the grey-weave influences how much the weave will shrink and the dimension change of the weave may influence the appearance of waves and needs more investigation. / Program: Magisterutbildning i textilteknologi

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