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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.
71

Proposta de modelo de gestão de estoque, em empresas de manufatura contratada, utilizando sistema de apoio à decisão / Proposal for a model of inventory management in contract manufacturing companies, using decision support system

Ramos, José, 1948- 10 July 2013 (has links)
Orientador: Antonio Batocchio / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T03:10:46Z (GMT). No. of bitstreams: 1 Ramos_Jose_D.pdf: 5427777 bytes, checksum: 0fc00db4fd4147b24ce787a2973fbe20 (MD5) Previous issue date: 2013 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The complete abstract is available with the full electronic document / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica
72

Avaliação energética de dois sistemas de produção de milho

Bernardi, Lorena de Moraes 22 August 2008 (has links)
Made available in DSpace on 2014-08-20T14:33:07Z (GMT). No. of bitstreams: 1 Dissertacao_ Lorena_ Moraes_ Bernardi.pdf: 2986902 bytes, checksum: b4621b4cf077e4399295aa2882c48ccc (MD5) Previous issue date: 2008-08-22 / Consumption of energy in a system of production is one of the most worrying things in agricultural activity. Accordingly, the calculation of the energy balance is one of the most important tools when you want to assess the sustainability of agroecosystems. This study aimed to evaluate the consumption and production of energy in two systems of production of corn, one of ecological base and other conventional, developed in two agricultural properties, both located in Pelotas/RS. Questionnaires modified in Marchioro (1985), were applied to farmers, with the aim of characterizing the production units, the composition of families, the hours devoted to each operation and management practices and types and quantity of inputs used. By the existing scientific literature, the equivalent energy were identified that are present in the stages of production processes, which led to measure the consumption (input), energy (human / animal activity, agricultural chemicals, fuel ...) and the energy produced (output) for biomass derived from their systems, which was obtained through the collection of a sample of the population of corn plants chosen at random, which after passing through processes of drying and weighing in laboratory provided data representative of the total production of biomass in cultivated areas, data which were finally converted into equivalent energy production. The entrances and exits of energy in both systems were related and led their respective energy balances. The total consumption of energy in 1 (one) hectare of the ecological base system of production (1,38 MJ) is lower than in 1 (one) hectare of conventional system (5.789,10 MJ) and energy production in the same area proved to be greater in the production system of ecological base (321.225,30 MJ) than in conventional (166.055,02 MJ). It was confirmed that the energy balance in the ecological base system of production (232,93) is most effective when compared to the conventional system (29,20). / O consumo de energia num sistema de produção é um dos aspectos mais preocupantes na atividade agrícola. Nesse sentido, o cálculo do balanço energético se constitui numa das mais importantes ferramentas quando se quer avaliar a sustentabilidade de agroecossistemas. O presente trabalho teve como objetivo avaliar o consumo e a produção de energia em dois sistemas de produção de milho, um de base ecológica e outro convencional, desenvolvidos em duas propriedades agrícolas, ambas localizadas no município de Pelotas/RS. Questionários modificados de Marchioro (1985), foram aplicados aos agricultores, com a finalidade de caracterizar as unidades de produção, a composição das famílias, as horas dedicadas à cada operação e práticas de manejo e tipos e quantidade de insumos utilizados. Com embasamento na literatura científica existente, foram identificados os equivalentes energéticos que se fazem presentes nas etapas dos processos de produção, os quais permitiram mensurar o consumo (input) de energia (atividade humana/animal, agroquímicos, combustível...) e a energia produzida (output) pela biomassa oriunda dos respectivos sistemas, a qual foi obtida através da colheita de uma amostra da população de plantas de milho escolhidas ao acaso, que após passarem por processos de secagem e pesagem em laboratório forneceram dados representativos da produção total de biomassa nas áreas cultivadas, dados esses que foram por fim convertidos em equivalentes energéticos de produção. As entradas e saídas de energia em ambos os sistemas foram relacionadas e originaram seus respectivos balanços energéticos. O consumo de energia total em 1 (um) hectare do sistema de produção de base ecológica (1,38 MJ) é menor que em 1 (um) hectare do convencional (5.789,10 MJ) e a produção de energia na mesma área mostrou-se maior no sistema de produção de base ecológica (321.225,30 MJ) que no convencional (169.055,02 MJ). Confirmou-se que o balanço energético no sistema de produção de base ecológica (232,93) é mais eficiente se comparado ao convencional (29,20).
73

The development of water quality guidelines for poultry production in southern Africa

Coetzee, Christel Blanche 16 July 2008 (has links)
The objective of this study was to develop water quality guidelines for poultry reared under South African conditions and production systems. This was achieved by a modeling approach that was based on a survey of water used by poultry producers throughout the country. Potentially hazardous constituents identified were – Sodium, Magnesium, Chloride, Sulphate, Nitrate, Calcium and Phosphorus. Three experiments were conducted to test these constituents’ effects on poultry production. Experiment 1 examined the influence of different levels of magnesium, sodium, sulphate and chloride in the drinking water of layers and the effect thereof on their production. The study showed that 12 different combinations of Mg, Na, Cl and SO4 had no significant effect on growth, food and water intake, and egg production or egg quality. Poultry producers in areas with naturally high levels of these minerals in their ground water can therefore continue to function successfully if the concentrations present are up to 250 mg/l of Mg, 500 mg/l of Cl, 500 mg/l of SO4 and 250 mg/l of Na. Experiment 2 examined the effect of elevated levels of NaNO3 in the drinking water of layers and broilers. No negative effects on broiler production and growth were observed. The only mineral ion to show a significant effect on performance was nitrate, with lower nitrate concentrations in well water being associated with better performance. Experiment 3 examined the effects of Ca and P in the drinking water on egg production, egg quality, bone integrity and shell strength. The results showed that water can be a valuable asset to increase eggshell integrity, but waterline maintenance may be increased because of the tendency of calcium to precipitate. Water should be seen as a dietary source of minerals (Ca + P) and should be taken into consideration when nutrient specifications are set for feed formulations to be used in the various poultry production systems. The preceding results served as basis for developing a modeling approach to water quality guidelines for poultry. / Thesis (PhD (Animal Science))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted
74

Effects of production systems on the muscle energy status post mortem and meat quality of beef cattle

Du Toit, Elsabe 20 July 2012 (has links)
This study was part of a larger study to develop an animal production model to obtain the optimum beef tenderness. There is a variety of different beef production systems being used in South Africa. The production systems investigated in this study were; animals reared on pasture until A age classification group (AP), animals reared on pasture until AB age classification group (ABP), animals reared on pasture until B age classification group (BP), animals reared at a feedlot until A age classification group (AF) and animals reared at a feedlot until AB age classification group (ABF). These production systems affect a wide range of components in the muscle that contribute to meat quality. Meat quality refers mainly to tenderness and colour. Scientists and industry role players are uncertain of which production system is the best to produce high quality meat. The aim of the study was to determine the effects of different production systems on the post slaughter muscle energy metabolism and the related effects on meat quality (tenderness and colour). In the experiment 180 steers of the following breed crosses were used: Nguni, Simmental and Brahman. These animals were reared until they reached the A, AB or B age classification, either on pasture or in a feedlot (B only on pasture). All the carcasses were electrically stimulated for approximately 15 sec, before analyses were done. The following properties were measured on the animals after slaughter: tenderness (Warner-Bratzler shear force), carcass pH, carcass temperature, sarcomere lengths, myofibrillar fragmentation length, calpain activity, muscle lactic acid concentration, muscle glycogen concentration, muscle ATP concentration, muscle glucose-6- phosphate concentration, muscle creatine phosphate concentration, muscle glucose concentration, water holding capacity, drip loss and meat colour. These measurements and determinations were done according to standard laboratory procedures at the ARC (Agricultural Research Council) at Irene. Breed had no effect on the muscle energy status for muscle glycolytic potential, muscle lactic acid concentration, muscle glucose concentration, muscle glycogen concentration, muscle glucose-6-phosphate concentration, muscle ATP concentration and creatine phosphate concentration (p>0.05). Older animals from the pasture had lower muscle energy levels than younger animals from the feedlot. Animals from the BP production system had the darkest colour meat with the highest hue angle. AF production system animals had the lightest colour meat with the lowest hue angle and the highest chroma. ABF production system animals had the lowest chroma. Animals from the ABF production system had the lowest shear force value at 1, 7 and 14 days post mortem and animalsfrom the AP production system had the highest shear force value at 1, 7 and 14 days post mortem. This study showed that the energy status in the muscle post mortem does not influence the tenderness of the meat nor the colour (p>0.05). Shear force had a weak to medium positive correlation with muscle pH (between 0.186 and 0.410) and a weak to medium negative correlation with muscle temperature (between -0.157 and -0.268) (p<0.05). Muscle lactic acid concentrations (between -0.033 and -0.322), muscle glucose concentrations (between -0.066 and -0.155) and sarcomere length (between -0.276 and -0.326) had a weak to medium negative correlation with shear force (p<0.05). Muscle glycogen concentrations (between 0.026 and 0.166) and myofibrillar fragment length (between 0.248 and 0.447) had a weak to medium positive correlation with shear force (p<0.05). Shear force had a weak positive correlation with calpastatin activity (between 0.064 and 0.253) and a weak to medium negative correlation with calpain I activity (between -0.183 and -0.313) (p<0.05). The ratio of calpastatin: calpain I (between 0.323 and 0.348) and the ratio of calpastatin: calpain I + II (between 0.183 and 0.275) had a weak to medium positive correlation with shear force (p<0.05). Breed had no effect on the muscle energy status for muscle glycolytic potential, muscle lactic acid concentration, muscle glucose concentration, muscle glycogen concentration, muscle glucose-6-phosphate concentration, muscle ATP concentration and creatine phosphate concentration (p>0.05). If electrical stimulation was not used in this study the difference between the production systems in terms of muscle energy status and colour would have been more prominent. The conclusion is that if animals are slaughtered under “ideal” circumstances in terms of stress being kept to a minimum before slaughter and the carcasses are electrically stimulated in order to prevent cold shortening, the production system shows a small effect on the energy status of the animal and consequently also levels out the meat quality characteristics such as tenderness and colour. For more dramatic results and academic value it would have been more useful to include more variations of non-ideal slaughter conditions and non-electrical stimulation, as well as more breeds. A follow up study with no electrical stimulation can be helpful to explain some uncertainties. This follow up study will present its own challenges, for example higher frequency of DFD. A follow up study on the effects of a larger variety of breeds can help to determine the exact effect ofmuscle energy metabolites in the different breeds, on the tenderness and colour of the meat. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted
75

Desempenho e potencial agroeconômico da produção de etanol em microdestilarias em pequenas propriedades na região noroeste do Rio Grande do Sul

Oderich, Edmundo Hoppe January 2013 (has links)
A crescente escassez dos combustíveis fósseis tem indicado a necessidade de diversificação da matriz energética mundial. Nesse contexto, a produção de biocombustíveis figura entre as alternativas energéticas. No entanto, tal alternativa não é suscetível de uma só interpretação, havendo divergências acerca de suas consequências. Em meio ao debate, movimentos sociais do campo têm realizado experiências que buscam aliar a produção de biocombustíveis ao incremento da renda de pequenos agricultores. O tema central do presente estudo foi a produção de etanol em microdestilarias pelo Movimento dos Pequenos Agricultores através de uma de suas cooperativas, localizada no Noroeste do Rio Grande do Sul. O objetivo da pesquisa foi examinar o desempenho e o potencial agroeconômico do sistema de produção proposto pela COOPERBIO nas unidades familiares de produção agrícola (UPAs) a ela vinculadas. O estudo referenciou-se na Teoria dos Sistemas aplicada à investigação de realidades agrárias complexas e nas ferramentas metodológicas disponibilizadas pela mesma, apoiando-se ainda na ideia desenvolvida por Ploeg acerca da condição camponesa e do modo camponês de fazer agricultura. Realizou-se também uma revisão de literatura acerca da problemática dos biocombustíveis e da importância de modelos energéticos alternativos. Os procedimentos metodológicos consistiram em pesquisa documental, observação direta e entrevistas semiestruturadas a agricultores e técnicos da COOPERBIO, analisando exaustivamente duas microdestilarias e quatro unidades de produção representativas da cooperativa. Do ponto de vista socioeconômico, constatou-se que a baixa disponibilidade de terra e o elevado valor agregado bruto decorrente da intensificação baseada no trabalho constituem as principais características comuns entre as UPAs analisadas, assim como uma renda agrícola média anual em torno de R$ 1500,00 por hectare, a despeito da variação dos sistemas de produção encontrados. Em relação à produção em microdestilarias, verificou-se que a proposta da COOPERBIO está tecnicamente adequada à realidade das UPAs. Do ponto de vista econômico, os subsistemas produtivos ligados às microdestilarias tem sido mais vantajosos que a maioria dos demais subsistemas encontrados nas UPAs. No entanto, constatou-se que as microdestilarias têm sido subutilizadas pelos agricultores. O motivo principal parece residir na inconclusão da implantação do arranjo produtivo proposto e nas consequentes dificuldades de comercialização do etanol, que por sua vez têm acarretado na falta de capital de giro do empreendimento e de agilidade na remuneração dos agricultores. Sanados os desafios, a produção de etanol em microdestilarias conforme a proposta da COOPERBIO parece ter potencial para incrementar a renda, fortalecer a campesinidade de pequenas UPAs e contribuir na diversificação da matriz energética brasileira. / The growing scarcity of fossil fuels has indicated the need to diversify sources of energy worldwide. In this context, production of biofuels emerges as an alternative energy. However, this alternative is not susceptible of only one interpretation, with disagreement about its consequences. Amid the debate, rural social movements have conducted experiments that seek the production of biofuels combined to income increase of small farmers. The focus of this study was the production of ethanol micro distilleries by the Movement of Small Farmers through their cooperatives, located in the northwest of Rio Grande do Sul. The objective of the research was to examine the agrieconomic performance and potential of the production system proposed by COOPERBIO in family farming units (UPAs) linked to it. The study referenced in the Systems Theory applied to the investigation of complex agrarian realities and the methodological tools available for the same, also leaning on the idea developed by Ploeg about the condition of the peasant and peasant way of doing agriculture. It also presents a literature review on the issue of biofuels and the importance of alternative energy models. The methodological procedures consisted of desk research, direct observation and semistructured interviews with farmers and COOPERBIO cooperative technicians, deeply analyzing two micro distilleries and four representative production units of the cooperative. Socioeconomically, it was found that the low availability of land and the high gross added value resulting from the intensification based on the work are the main common features between the analyzed UPAs, as well as an average annual agricultural income of around R$ 1500,00 per hectare, despite the production systems variation found. In relation to the production of micro distilleries, it was found that COOPERBIO proposition is technically appropriate to the realities of UPAs. From an economic standpoint, the subsystems related to productive micro-distilleries have been more advantageous than most other subsystems found in the UPAs. However, it was found that the micro-distilleries have been underutilized by farmers. The main reason seems to lie in the incompleteness of the implantation of the whole production arrangement and consequent difficulties on selling the ethanol, which have entailed the lack of working capital of the enterprise and agility in paying farmers. Solved challenges, ethanol production in accordance with the COOPERBIO proposition of micro distilleries seems to have the potential to increase income, strengthen rural communities and small UPAs and contribute in diversifying the Brazilian energy matrix.
76

Análise de cenários de fluxo de pedidos e demandas aplicados em uma empresa do segmento automobilístico

Sergio de Araujo 19 December 2012 (has links)
As intensas evoluções do mercado forçam as empresas a adequarem seus negócios abordando novos meios estratégicos para se manterem competitivas diante de seus concorrentes. O objetivo do trabalho é analisar novos arranjos produtivos encontrados no segmento automobilístico que se destacam por necessitar de uma forma cada vez melhor de relacionamento com seus clientes através de uma modelagem do sistema para disponibilizar a visibilidade do estoque nos diversos estágios como: antes da produção, durante a produção, durante o transito, quando estocados nos pátios e até possibilitando a colocação de pedido para itens que não estão disponíveis nos estágios anteriores citados. O trabalho também aborda um estudo de previsão de demanda que utiliza modelos matemáticos sobre a média da quantidade de vendas apuradas em determinado período de tempo e um comparativo com o método dos mínimos quadrados. A consequência do engajamento dos pedidos nas etapas anteriores da real disponibilidade física dos produtos para comercialização e entrega, propõe otimizar os níveis de estoque em quantidades mais baixas do que o modelo atual. Os cenários são simulados e visam contribuir como ferramenta para demonstrar a viabilidade de um novo modelo de política de comercialização dos produtos. / The intense Market developments force companies adapt their business by addressing new strategic means to remain competitive in the face of its competitors. The objective is to analyze new production arrangements found in the automotive sector that need to stand out by an ever better relationship with its customers through a modeling system to provide inventory visibility in different stages such as: before production, during production, during transit, when stored in the courtyards and even allowing for the placement of order for items that are not available in earlier stages cited. The paper also discusses a study of demand forecasting which uses mathematical models to average volumes calculated requests in a given time period and a comparison with the least squares method. The result of the engagement of requests in previous stages of actual physical availability of products for sale and delivery, proposes optimize inventory levels in amounts lower than the current model. The scenarios are simulated and aim to contribute as a tool to demonstrate the feasibility of a new model of political marketing.
77

Real-time Analysis and Control for Smart Manufacturing Systems

January 2020 (has links)
abstract: Recent advances in manufacturing system, such as advanced embedded sensing, big data analytics and IoT and robotics, are promising a paradigm shift in the manufacturing industry towards smart manufacturing systems. Typically, real-time data is available in many industries, such as automotive, semiconductor, and food production, which can reflect the machine conditions and production system’s operation performance. However, a major research gap still exists in terms of how to utilize these real-time data information to evaluate and predict production system performance and to further facilitate timely decision making and production control on the factory floor. To tackle these challenges, this dissertation takes on an integrated analytical approach by hybridizing data analytics, stochastic modeling and decision making under uncertainty methodology to solve practical manufacturing problems. Specifically, in this research, the machine degradation process is considered. It has been shown that machines working at different operating states may break down in different probabilistic manners. In addition, machines working in worse operating stage are more likely to fail, thus causing more frequent down period and reducing the system throughput. However, there is still a lack of analytical methods to quantify the potential impact of machine condition degradation on the overall system performance to facilitate operation decision making on the factory floor. To address these issues, this dissertation considers a serial production line with finite buffers and multiple machines following Markovian degradation process. An integrated model based on the aggregation method is built to quantify the overall system performance and its interactions with machine condition process. Moreover, system properties are investigated to analyze the influence of system parameters on system performance. In addition, three types of bottlenecks are defined and their corresponding indicators are derived to provide guidelines on improving system performance. These methods provide quantitative tools for modeling, analyzing, and improving manufacturing systems with the coupling between machine condition degradation and productivity given the real-time signals. / Dissertation/Thesis / Doctoral Dissertation Industrial Engineering 2020
78

Návrh technologie výroby a výrobní linky pro výrobu pístů / A lay-out of production technology and production line for manufacturing of pistons

Vilhelm, Michal January 2012 (has links)
This final thessis deals with the complex technological preparation of pistons manufacture,ie, technological preparation and technological part of project preparation. The content of production technological preparation is to determine the number and sequence of technological operations, control plans, selection of appropriate production machines using progressive production methods, design tools and jigs for clamping pistons and the choice of cutting conditions for machining individual operations. Technological preparation of production specify the relationships between individual elements of the manufacturing system, ie the spatial machines distribution and operation times requirements, technology, handling, control, and other activities with maximum use of automation to increase productivity and economic efficiency of production process. The aim is to design an optimal piston technology for maximum productivity and production frugality.
79

Optimizing Controlled-Release Fertilizer for Lettuce and Mizuna Grown on the International Space Station

Asmaa H Morsi (8071979) 04 December 2019 (has links)
<p>Astronaut diets on the International Space Station (ISS) depend on resupplied packaged food. However, missions to Mars of 3-5 years will not accommodate re-supply. In addition, many human macro and micronutrients degrade during long-term storage. Thus, growing nutritional plants aboard ISS is essential for providing astronauts with fresh, healthy produce. NASA is usingan experimental vegetable- production unit called VEGGIE to grow fresh salad crops aboard ISS to provide astronauts with healthy diets. VEGGIE is a small plant-growth chamber designed as a garden for astronauts that is low in mass and has a low power requirement. Veggie is equipped with light-emitting diodes (LEDs) but is exposed to the ISS cabin environment. Plants are grown with roots in a baked-ceramic substrate (arcillite) incorporating controlled-release fertilizer (Nutricote) and wicks delivering water by capillary action from a reservoir.</p><br><div>The fertilizerprills release nutrients into arcillite slowly over time. Different controlled-release types have the same amount of fertilizer but release it over different time periods. The Purdue Mitchell lab in collaboration with NASA is testing growth of salad crops within VEGGIE analogs under ISS-like environments in a growth chamber. Specifically, we are evaluating effects of different controlled-release fertilizer treatments as well as different substrate particle sizeson “cut-and-come-again” harvest scenarios, comparing productivity and quality of Lettuce as well as anAsian salad crop called Mizuna.<br></div><div><br></div><div>SS environments being mimicked include temperature: 24/21°C D/N, CO2: 2800 PPM D/N, RH: 45-50% D/N, and photoperiod: 16hours.Arcillitemedium contained one oftwo different fertilizer mixes: 7.5g18-6-8 T 70 + 7.5g 18-6-8 T100, or 7.5g18-6-8 T70 +7.5g 18-6-8 T180fertilizer/liter medium. LED Light treatment provides atotal PPFDof 330µmol m--2s-1 PAR; with 270µmol m--2s-1Red(R), 30µmol m--2s-1Blue (B), and 30µmol m--2s-1Green (G). Plants are grown under those conditions for 8 weeks, and harvested three times at 28, 42, and 56 days from planting. At each harvest, yield parameters as well as tissue mineral content have been measured for optimum fertilizer treatment selection.<br></div><div><br></div><div>Lettuce and Mizuna plants grown in a mix of 100% fine substrate particles (Profile) and fertilizer treatment of 50% T100:50%T70 had the higher yield as well as nitrogen contentcompared to those grown in 50%T180:50%T70. Growing mizuna plants in 100% profile resulted in higher shoot fresh weight; although no significant differences occurred for shoot dry weight. In addition, there was no significant interaction between substrate and fertilizer, which is reported by other research as one of the advantages of using controlled-release fertilizer<br></div>
80

Multifunctional production systems in Brazil : Opportunities, barriers, and implementation

Jonson, Sofia January 2020 (has links)
As populations grow and the call for renewable energy increases, so does the demand for biomass. However, the sustainability of biomass production has been debated. Concerns involve both negative environmental impacts from agricultural production, as well as the effects of increased bioenergy use on food security. Multifunctional production systems are a potential solution to these issues where environmental benefits are promoted in addition to maintained or enhanced biomass output. This study investigates multifunctional production systems in Brazil, as well as incentives and barriers for implementation within the Brazilian context. A systematic literature review was used to identify previous research on multifunctional production systems in Brazil. The review was then complemented by semi-structured open-ended interviews with local experts. The study found that even though common terminology from the field of multifunctional production systems was not frequently used in the Brazilian context, the systems were both studied and implemented. It was also concluded that economic feasibility is a prerequisite for successful implementation. However, factors like environmental circumstances, farmers perceptions, knowledge, and traditions are also important. Thus, effective adoption requires strategies combining economic incentives, policy incentives as well as educational tools. / <p>2020-06-13</p>

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