113 resultados para válvulas


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Engenharia Elétrica - FEIS

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The cylinder head contains the combustion chamber for the air-fuel mixture and the intake and exhaust valves, the valve guide and the valve seat. The cylinder head also is a support for the camshaft and valve rocker. The holes where the spark plugs are connected are designed to fit the better place in the combustion chamber. The cylinder heads often are manufactured using materials such as aluminum and cast iron. The cooling fins located in the outside of the cylinder head are designed for a good heat transfer and therefore their dimensions and positioning are important. This work aims the calculation for a cylinder head to be installed in a 400 cc displacement, gasoline powered, four stroke, single cylinder engine. According to the displacement it will be analyzed the combustion chamber, the intake and exhaust valves, as well as the camshaft and rocker arms. This also a work to help to accomplish the design of a single cylinder engine, where the alternatives parts, cylinder block and crankcase are all already machined and assembled in this campus

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The search for materials with higher properties and characteristics (wear resistance, oxidation, corrosion, etc.) has driven research of various materials. Among the materials that are being studied with such properties and characteristics are super alloys based on nickel which has an important role in the aeronautical, automotive, marine, production of gas turbines and now in space vehicles, rocket engineering , experimental aircraft, nuclear reactors, steam-powered plants, petrochemical and many other applications because besides having all the characteristics and properties mentioned above also have an excellent performance at high temperatures. The super alloy based on nickel studied in this work is the super alloy Pyromet 31v normally used in the manufacture of exhaust valves in common engines and diesel engines of high power by cater requirements such as mechanical strength and corrosion resistance at temperatures of approximately 815 ° C. The objective of this work is to produce results to demonstrate more specific information about the real influence of coatings on cutting tools and cutting fluids in turning and thus promote the optimization of the machining of these alloys. The super alloy Pyromet 31v was processed through turning, being performed with various machining parameters such as cutting speed, feed rate, depth in conditions of Minimum Amount of Fluid (MAF), abundant fluid, cutting tools with coating and without coating in early in his work life and with wear. After turning were obtained several samples of chips and the part generated during the machining process, was measured roughness of the material, subsequently made macrostructural analysis of the tools used order to detect possible wear and microstructural analysis of samples collected being that the latter was used for Optical Microscopy, Scanning Electron Microscopy (SEM) and ... (Complete abstract click electronic access below)

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Pressure drop and energy efficiency of compressors in chemical plants are the focus of this study. Its objective is an analysis of possible sources of energy loss through the study of pressure loss in pipes, calculation of thermodynamic efficiency of the compressors. Important issues are raised for this analysis such as the types of compressors, the operating range of each compressor, compression types, as well as a study of accessories such as filters and valves. After studying these issues was carried out calculations of pressure drop step-bystep and with a software WIPCD. Followed by the calculation of efficiency of compressors and monthly energy cost of each compressor in operation. Finally, the study shows some suggestions for immediate improvements, changes and suggestions for possible future purchases of compressors

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This work studies the most commonly used methods and make comparisons and discussions of the findings made by each of them and the results provided by them. The objective of this research was to show that the method of characteristics is currently the most efficient method to perform these simulations because of its broad scope low simplifications, requirement allowing to consider every detail of the pipe and fluid. Manual calculations are performed and also a software capable of calculating this phenomenon for various situations, such as water pump, elevated tanks, valves and quick maneuver was developed. The software is based on the method of characteristics that is currently recommended by ABNT. These methods, and the results are obtained numerically and graphically are adopted pipes and amount of downstream conditions and in which will be applied. The conclusions reached showed that the Allievi method is widely used yet because of its efficiency and quick calculation for simple pipes. The method of characteristics, although a lot of work to be calculated due to the calculation is iterative process and requires a program to use it, is the only one that allows the calculation with all amount to the conditions situations and downstream of all the pipe possibilities found

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Pós-graduação em Engenharia Mecânica - FEG

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The oral anticoagulants (AOC) and platelet antiagregants are drugs used for the prevention of thromboembolic phenomena, such as pulmonary embolism in patients with atrial fribrilation heart valves, thrombosis and pulmonary embolism. For patients who are undergoing surgical procedures-dentistry were asked to discontinue the use of anticoagulants until the value of the INR remained = 2.0, that in order to avoid trans and hemorrhages in the postoperative period. However, the AOC can cause the formation of a clot, leading to obstruction of blood pathways. Thus, it became doubtful the medicine for surgery, in which local hemostatic measures would be sufficient to promote hemostasis. Thus, the objective of the review was to evaluate the risk of bleeding in patients AOC users that are subjected to surgical procedures, through a bibliographical survey carried out in relevant clinical studies published between 1990 and 2012, by the MedlinePubMed data. In this review of literature was concluded that the benefit of thromboembolism prevention overcomes the risk hemorrhage, therefore, it is recommended to keep the dose of anticoagulant therapy unchanged for patients undergoing oral surgery and implant dentistry, using appropriate INR levels with the assistance of local hemostatic. In addition, a refined surgical technique should be performed in these patients. With respect to the most invasive oral surgery, with a risk of bleeding, treatment may be necessary in conjunction with the medical staff.

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Pós-graduação em Engenharia Mecânica - FEIS

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The modernization of the world made the speed, accuracy and reliability of all existing processes become increasingly necessary. For this evolution to occur every day, the evolution of the equipment was strategic, but not as much as needed. It is necessary for such equipment to ensure its function and, in case of failure, an early diagnosis to prevent loss. Therefore the evolution of maintainability and reliability in equipment is also paramount. Thus, the growth of forms of maintenance was driven by this scenario, forming maintenance philosophies. Among many, there is the RCM, which have its focus on the identification, parameters development and performance preview. One of those methodologies from this idea is the FMEA, process that has been studied and implemented this work, aiming the anticipation of failure modes and guidance for the use of a heat exchanger and a pump. This implementation has the aid of another process of RCM, the PHA, which was also shown and implemented, these results being used to start the FMEA process. The results show the activities with the highest chance of failure, presenting also the measures to be taken to avoid or minimize them. It is shown, in this paper, concern with the valves because they maintain control and system security, and its flaws related to accidents with possible danger to people and the whole system, emphasizing the priority of action

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The modernization of the world made the speed, accuracy and reliability of all existing processes become increasingly necessary. For this evolution to occur every day, the evolution of the equipment was strategic, but not as much as needed. It is necessary for such equipment to ensure its function and, in case of failure, an early diagnosis to prevent loss. Therefore the evolution of maintainability and reliability in equipment is also paramount. Thus, the growth of forms of maintenance was driven by this scenario, forming maintenance philosophies. Among many, there is the RCM, which have its focus on the identification, parameters development and performance preview. One of those methodologies from this idea is the FMEA, process that has been studied and implemented this work, aiming the anticipation of failure modes and guidance for the use of a heat exchanger and a pump. This implementation has the aid of another process of RCM, the PHA, which was also shown and implemented, these results being used to start the FMEA process. The results show the activities with the highest chance of failure, presenting also the measures to be taken to avoid or minimize them. It is shown, in this paper, concern with the valves because they maintain control and system security, and its flaws related to accidents with possible danger to people and the whole system, emphasizing the priority of action

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Patients with hydrocephalus and risk factors for overdrainage may be submitted to ventricular shunt (VS) implant with antisiphon device. The objective of this study was to prospectively evaluate for two years the clinical and tomographic results of the implant of fixed-pressure valves with antisiphon device SPHERA (R) in 35 adult patients, with hydrocephalus and risk factors for overdrainage. Of these, 3 had congenital hydrocephalus in adult patients with very dilated ventricles (Evans index >50%), 3 had symptomatic overdrainage after previous VS implant (subdural hematoma, hygroma or slit ventricle syndrome), 1 had previous chronic subdural hematoma, 15 had normal pressure hydrocephalus with final lumbar pressure <5 cm H2O after tap test (40 mL), 6 had pseudotumor cerebri, and 7 had hydrocephalus due to other causes. Clinical improvement was observed and sustained in 94.3% of the patients during the two-year period with no computed tomography (CT) evidence of hypo or overdrainage, and no immediate early or late significant complications.