995 resultados para CFD (Cálculos computacionales de mecánica de fluídos)
Resumo:
Work organized in shifts, either for technological, social or economic imposition, allows the best use of means of production, increasing the overall productivity of the enterprises. At the same time, this type of work harms the individual productive capacity of workers, particularly those involved in the night shift. The objective of this work was to assess the behaviour of production in a continuous line and subjected to work organized in shifts. Through the statistical method of analysis of variance, Spearman's test and Tukey's method, was analysed the distribution of the productivity index measured in three fixed shifts of work in a glass company. The productivity index, provided by the integrated management system of the company, refers to the ratio of actual productivity to total productivity. The statistical analysis shows that factors of production, such as allocation of workers, do not interfere with productivity, showing an unexpected pattern, where the average productivity for the three shifts are close and the correlation between the number of workers on the line and productivity is low. The conditions of production had an adverse work environment with exposure to noise, heat, vaporized mist of lubricating oil and risk of accidents. The findings show that the calculation of productivity in use is limited and its use in company’s production control may produce distortions. It is proposed to examine alternative calculations methods that consider the overall productivity
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In 2002, the Ministry of Education (MEC) published the Curriculum Guidelines for Engineering courses in the country. The Guidelines contain subjects like the profile of graduates, the course structure, curriculum, internships and skills and abilities, all geared to guide the training of engineers in Brazil. The objective of this study is to evaluate together with teachers of the Production Department of this University and students of the fifth year of Production Engineering is how student learning of Production Engineering for the development and importance of skills within the course and skills for engineers who are present in the Curriculum Guidelines for engineering courses developed by MEC
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The internal combustion engine is a heat engine widely used in the automotive industry. In order to better understand its behavior many models in the literature have been proposed in the last years. The 0-D thermodynamic model is a fairly simple tool but it is very useful to understand the phenomenon of combustion inside the chamber of internal combustion engines. In the first phase of this work, an extensive literature review was made in order to get information about this kind of analysis and, after this, apply them in a model able to calculate the instantaneous temperature and pressure in one zone of the combustion chamber of a diesel engine. Therefore some considerations were made with the aim of increasing the accuracy of the model in predicting the correct behavior of the engine, adding the combined effects of heat transfer, leakage and injection. In the second phase, the goal was to study the internal flow of a three-dimensional model of an internal combustion engine. In order to achieve this goal the software Solidworks was used to create the geometries of an engine and the suite of softwares Ansys was used to create the moving mesh (ICEM CFD and CFX-Pre) and to solve the CFD problem (Ansys CFX code). The model was able to perform the air flow simulation during the four-stroke cycle of an engine: admission, compression, expansion and exhaust. The results obtained from both models were suitable and they open a new range of possibilities for future researches on the field
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The need to reduce environmental damage and add value to waste causes more and more new alternatives appear to unite these two points. One of the main ways to achieve this in timber industries and the use of waste for making panels. This work was aimed at studying the influence of particle size and density in Eucalyptus mechanical compressive strength of cement composite wood. For this study was performed production and physico-mechanical characterization of specimens, using portland cement, water and waste eucalyptus. The methodology consists of a statistical study of the results obtained by calculating the density and axial compression tests and a subsequent comparison of these results with other studies. The results showed that there are significant differences in density and compressive strength when using different particle sizes the particles of eucalyptus. In general, the smaller the particle size, the lower the compression strength and the greater the density when the samples are produced with the same trait
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This work aims to determine the stresses acting on the main beam of a crane to transport steel coils of up to twelve tons. To determine the stress it was made a revision of the knowledge of the mechanics of materials to apply the analytical method. Following a review of the finite element method is made to understand the same. To complete the study it was used the commercial software ANSYS to determine the stresses by finite element method, the program provides images that help to better understand the results obtained. With the results a comparison of the values of the tensions between the two methods (analytical and finite element) was made. To assist in the calculations it was used the NBR 8400, 1984 (Calculation of Lifting Equipment Load)
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The study of physical and mechanical properties of wood is essential for its structural use and it is of great importance to the construction industry. Thus, this study aimed to determine the physical and mechanical properties of the wood Amaru - a hybrid of Eucalyptus, developed by Plantar Projects and Forest Products Ltda. In order to determine the properties of Amaru, round samples were used, which were provided to the Laboratory of Wood and Wooden Structures of the School of Engineering of São Carlos, University of São Paulo - LaMEM / EESC / USP. For the characterization of the physical properties, the apparent specific gravity and moisture content of the samples were determined. To the mechanical characterization, the following properties were evaluated: strength and stiffness in compression, strength and stiffness in bending, shear and tension. The procedures of the tests performed in this study were done according to the recommendations of the Brazilian Wood Standard ABNT NBR 7190:1997. The specimen used were confectioned in actual dimensions, according to as those used in the construction system proposed by Plantar. The results obtained from the tests performed showed that the mechanical properties approached the values proposed by the Wood Standard NBR 7190. The visual grading was important to provide a primary idea about the failure modes to be obtained from the tests performed. The bending test showed the modulus of elasticity (MOE) and Modulus of Rupture (MOR), which resulted in 15822 MPa and 101,7 MPa, respectively. The compression test resulted in values Ec0,m and fc0, 15698 MPa and 50,7 MPa. The tensile strength (ft0) of this hybrid was calculated and its value obtained was 60,8 MPa. The shear strength (fv0) was 8,2 MPa. The results obtained from the tests are the basis for engineers and architects to design structures using wood species Amaru
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Increasingly competitive markets have driven the search for companies in many different ways to win and keep customers. The service level is basically the performance of companies in fulfilling the orders made, or how companies demonstrate to their clients efforts in their behalf. This work aims to solve the difficulties faced by a multinational company present in Brazil, in the distribution of its products in the category Ice Cream in order to improve the service level of their customers. Review the logistics network and concepts related to the distribution system of products is one of several ways to achieve this goal, as well as the use of IT and tools to assist in planning and programming of the physical distribution of products. In this study we used the concept of direct distribution system called Transit Point (TP). The TP provides at the same time, a strategy of rapid response, flexibility, low transportation costs and no inventory. A router - software capable of simulating the actual conditions experienced in the daily distribution - was used to assist in calculations. Results showed reductions of up to 47.5% in transportation costs and better conditions were provided in the distribution of products, positively impacting on service levels and in the maintenance of products quality, with a reduction of 1.6% of the total costs involve
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This work has the propose to discuss the National Examination Performance of students for the course in Production Engineering , from 2005 up to 2011, subsidies are shown how this came about assessment and how the course has been evaluated in recent years . Compares higher education from public and private universities in Brazil and is also discussed how important a good performance in the exam. Qualitative and quantitative surveys were conducted at different times that the work that enables a critical analysis of the examination , the institution and also the students themselves , so the list is the main motivators for the exam and also what should be done to obtaining good results in academic performance. Motivators for the exam has highlighted its importance is paramount and the consent of all involved from the beginning of the course to ensure that the examination is compulsory for all graduates of undergraduate manufacturing engineering in Brazil
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As normas nacionais e internacionais prevêem que a manutenção dos níveis de radiação deve estar abaixo do permitido. Sendo assim, a ICRP [1] (International Commission on Radiological Protection) exige métodos de otimização para garantir que o público esteja exposto aos menores níveis de radiação possíveis. Como método de otimização, aproximações teóricas e semi-empiricas podem realizar uma determinação do espectro de raios-X, sendo fundamental para o diagnóstico de energia, estimando a dose de radiações em pacientes e formulando modelos de blindagem. Métodos adequados de radioproteção foram desenvolvidos na física médica como a medicina nuclear, a radioterapia e a radiologia diagnóstica. Um dos métodos semi-empiricos utilizados é o modelo de TBC que é capaz de reproduzir e calcular os espectros gerados pelo anodo de tungstênio. Com o modelo de TBC modificado é possível também obedecer às exigências das barreiras protetoras presentes na radiologia, levando em conta a forma de onda arbitrária e a filtração adicional na geração do espectro não presente no modelo original. Além disso, realiza-se a calibração do espectro gerado para que o modelo de TBC represente a quantidade e comportamento de radiações típicas. Dessa forma, realiza-se uma revisão do modelo de TBC implementando-o ao programa matemático Matlab e comparando-o com os resultados adquiridos pelo Código MCNP-5 no Método de Monte Carlo. Os resultados encontrados são bastante satisfatórios, tanto em termos quantitativos quanto qualitativos dos feixes. Para a calibração, desenvolve-se uma análise dos espectros gerados pelo TBC Modificado aplicado ao programa Mathcad e Matlab sob as mesmas condições. Os espectros gerados apresentam o mesmo comportamento, diferindo em até 12% nos valores encontrados para camadas semi-redutoras, coeficiente de homogeneidade e energia efetiva
Análise estrutural de treliças espaciais no software Excel utilizando o médodo dos elementos finitos
Resumo:
The following paper means to develop a program to make structural analysis of space trusses. The program to be implemented was based on the concepts of the finite element method and used the programing resources of Visual Basic for Applications (VBA) for the Excel Software®. Being Excel® a software of easy access, low cost, capacity to make matrix calculations and with advanced resources of VBA programing, it is possible to develop an economic solution, efficient and precise for structural analysis of space trusses. Firstly is presented a finite elemento method and the space truss. Then is developed a few important algorithms to be used during the development of the program and also the use of a few resources of VBA. And to validate the quality, efficiency and precision of the results, these are compared with the established commercial software Ansys
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With the growing world energy demand mainly from developing countries like Brazil, Russia, India and China, the search for efficient sources of energy becomes a challenge for the coming years. Among the most widely used alternative sources, biomass is the one that grows in a more pronounced way. This study will assess the real possibility of having it as a heat source in an Organic Rankine Cycle, which employ heat transfer fluids as working fluids instead of water. From a regional data collection in agricultural production and their potential rice production and the resulting husk was defined as more appropriate. The availability of husks together with an amount of eucalyptus wood, provided by a company in the region on a monthly basis, were analyzed, and the low participation of the wood was discarded by the thermal contribution of little significance. Based on this, it was established the calorific value of fuel for thermodynamic calculations and the cycle to be used. It was then carried out the choice of working fluid from the literature and their availability in the library of software used for the simulations, the Engineering Equation Solver - ESS. The fluid most appropriate for the burning of biomass, Octamethyltrisiloxane (OMTS), was not included in the software and so the R227ea and R134a were selected. After the initial parameters modeling definition, as condensing temperature, efficiency and live steam conditions, the simulations were performed, and only the R227ea remained within the feasible thermodynamic and technological ranges. With this fluid the turbine power output was 265.7 [kW] for a scenario of 24 hours/day burning, 800.3 [kW] to biomass burning for 8 hours/day and 2134 [kW] for burning only 3 hours/day. The thermal efficiency of the cycle remained in the range of 6%, and for plants operating with the most... (Complete Abstract click eletronic access below)
Resumo:
In order to study resin distribution and homogeneity of composite laminates manufactured by RTM, it was used CYCOM 890 monolithic toughened epoxy as a matrix with two different configurations of intermediated modulus (IM) carbon fibers: Satin Weave (5HS) and non crimp fabric (NCF). The injection parameters were defined based on Thermo Gravimetric Analysis (TG), Differential Scanning Calorimetry (DSC) and rheological analysis. After processing the material, the resin/fiber impregnation was studied using ultrasonic test, Thermo Gravimetric Analysis, Differential Scanning Calorimetry, Dynamic Mechanical Analysis (DMA) and flexural tests. Therefore, it was able to observe an internal residual stress during the cooling process in both laminates, higher in the composite using NCF fabric due to the lack of symmetry, although a good proportion of fiber/matrix has been verified by the lower values of flexural modulus deviation. The DMA enabled the visualization of glass transition and its association with the inter and intra molecular interaction and movement, in which the NCF composite presented better permeability due to the lowest temperature of glass transition, when compared to the Satin Weave composite
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Patients that are mechanically ventilated in ICUs are constantly exposed to different pathogens, which present multiantibiotic resistance. Among these microorganisms, is MRSA (Meticillin-Resistant Staphylococcus aureus) considered to be a therapeutic challenge due to its resistance to β-lactam antibiotics. Therefore, this study proposed to identify species of Staphylococcus spp. isolated from mechanically ventilated patients in ICU, the gene mecA detection and the genes of the enterotoxins A (sea), B (seb), C (sec-1) and D (sed) in samples of S. aureus, as well as the phenotypic resistance determination to oxacillin using the disc-diffusion method with discs of oxacillin and cefoxitin. The samples collection occurred during in a period of 19 months, obtaining samples from 232 patients. A percentage of 39% (70) of Gram-positive cocci were found; which 82,8% (58) were identified as Staphylococcus spp,. among these, 75,8% (44) corresponded to S. aureus species and 47,7% were identified as MRSA. It was found resistance to both drugs in 31,8% of the S. aureus samples, 16 (36,3%) had the gene sea and 11 (25%) had the sec-1 gene. Among the coagulase-negative staphylococci obtained, the species most found was S. epidermidis, corresponding to 43% (6). The results revealed that one of the most important etiologic agents of VAP amid the Gram-positive cocci is the species S. aureus, with special attention to MRSA. The presence of enterotoxins genes in S. aureus did not showed determinant role in VAP, but the presence of these superantigens can contribute worsening the patient’s prognosis, since they are associated with intense inflammatory response
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Due to growing concerns for reducing environmental damage caused by the use of non-renewable raw materials, there is a growing demand for research related to aggregate technology with environmental preservation. Thus, the use of non-renewable materials and less aggressive materials has been gaining attention. About composite materials, the exchange of synthetic fibers by natural fibers, especially vegetable fiber as reinforcement, has been increasing, due to its physical-chemical properties such as mechanical strength, nontoxic, low cost, low density, processing flexibility, non-abrasive to the process equipment, requiring simple surface treatments, etc. This objective was to process composites reinforced with long fibers of sapegrass in epoxy matrix and characterize the composites through mechanical tests. Three groups of composites were prepared according to the treatment received by the reinforcement: without treatment, alkali treatment at concentration of 5% w/v and alkali treatment at 10% w/v concentration. The materials were analyzed by tensile and flexural, and tests also optical microscopy and scanning electron microscopy (SEM). The results were statistically analyzed. As the main result, the alkali treatment of 5% in the sapegrass fibers increases the tensile and flexural strength, as a consequence of the improve adhesion between matrix and reinforcement
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Because the high consumption of welded pipe for exploration and conduction oil and gas, optimization of manufacturing processes is necessary to obtain better productivity, efficiency and cost reduction. The objective of this study is to analyze the forms of heat transfer during the welding of pipes using longitudinal submerged arc process them to propose a model for the temperature distribution in the welded region. For this analysis are addressed as the heat transfer modes operate in the specified welding process and the necessary considerations for the mathematical model were obtained. The calculations were performed and the simulations needed to obtain the temperature distribution in the tube were carried out. Therefore, the practice was satisfactory and the results showed a range of temperatures along the pipe for a particular model and the future suggestions for improvement of this work