O estudo da usinagem em torneamento da superliga à base de níquel Pyromet 31v

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)

Cogeração em uma indústria automobilística

The search for energy efficiency improvement is a common concern in many companies. Cogeneration is a well known technique but not so spread in Brazil, despite its potential for energy costs reduction through heat recovery from prime movers. In this work, a preliminary technical and economic study is carried out for a cogeneration plant application in an automotive industry of São Paulo. Though mathematics modeling, three 2435 kW internal combustion engines are selected. When compared to the current status (no cogeneration), annual savings of about 2,2 MR$ are obtained, resulting a almost 3 years payback

Efeito da especificidade do treinamento (de fundistas e culturistas) sobre os indicadores bioquímicos do estresse obtidos em teste de esforço máximo em esteira e com pesos

Dezesseis atletas treinados em musculação (grupo AN = 7) ou em corridas de longa distância (AE = 9) foram submetidos a exercícios de máxima intensidade específicos e inespecíficos a sua modalidade de treinamento. A influência da especificidade do treinamento sobre as alterações promovidas por sessões agudas de exercício exaustivo nos parâmetros hemodinâmicos, de dano muscular e de estresse oxidativo foi analisada, e foram comparados os padrões de resposta aos exercícios entre os dois grupos. Os testes máximos consistiram de teste exaustivo em esteira, utilizando protocolo de rampa, e teste com pesos utilizando cargas iniciais de 80% de 1RM, progressivamente reduzidas, até a exaustão, em dois exercícios que abrangeram grupos musculares distintos. Foram realizadas coletas de sangue antes e imediatamente após os exercícios para a determinação de indicadores de hemoconcentração, de lesão muscular, de processo inflamatório e determinação de parâmetros hemogasimétricos. A glicemia se elevou significativamente após os testes somente para o grupo AE. Foram verificados aumentos significativos na acidose devidos a elevação das concentrações de lactato, H+ combinados a redução do HCO3-. Foram observadas variações significativas nas concentrações dos íons sódio e potássio. Também houveram aumentos significativos nas concentrações de CPK e DHL. Além disso, houveram elevações das concentrações plasmáticas e dos leucócitos. Dentro dos parâmetros analisados, as respostas observadas não foram uniformes em comparação aos dois grupos, e houve variação também interna aos grupos, quando comparados os exercícios específicos aos inespecíficos. Os resultados apontam que embora seja esperada uma resposta metabólica característica após o esforço físico exaustivo, a especificidade do treinamento é determinante sobre os processos adaptativos... (Resumo completo, clicar acesso eletrônico abaixo)

Redução de consumo de energia eletrica a partir de reaproveitamento de energia termica com uso de ciclo rankine orgânico

This paper is proposed the usage of an Organic Rankine Cycle (ORC) along with waste heat recovery from an inconstant heat source. This method of waste heat recovery with intermittent heat source is part of a technical viability study. This paper also brings up the usage of thermal energy storage as heat source for the ORC. This paper is based on a heat treatment company study in which a natural gas furnace is explored. Data such as mass flow, temperature and specific waste gas heat from this furnace are used through calculations. Calculations are made also based on furnace cycles. This viability study considers a series of working fluids such as ammonia, benzene, R113 and R134a. Results point out that ORC with out thermal storage and using refrigerant fluid ammonia is the best alternative

Reprodutibilidade das respostas metabólicas e cardiorrespiratórias fisiológicas em um protocolo de exercício intermitente realizado com recuperação passiva e ativa

The main objective of this study was to analyze the reliability of blood lactate concentration ([La]), oxygen uptake (VO2) and heart rate (FC) in an intermittent protoco, performed at 95%VO2max with passive or active recovery in untrained subjects. Participated of this study, active healthy males with 20 to 25 years, which were doing aerobic exercises witha weekly frequency of 3 sessions at least. The individulas performed, in different days, the following protocols in a cyclergometer: 1) An incremental test until exhaustion to determine maximal oxygen uptake (VO2max) and the intensity at VO2max; b) Two transitions at 95%VO2max for the determination of the VO2 kinetics parameters and; c) Two intermittent tests until exhaustion, with repetitions at 95% IVO2max and with durantion defined as being half of the duration of the slow component. The duration of the recovery was half of the duration of the effort (effort:pause of 2:1). This test was performed with passive (GP) and active recovery (GA). The VO2 and FC were measured continulously in both tests. Blood collections were performed for the determination of the [La]. There was significant correlação in both groups for VO2 (ATIVA - 0.94, PASSIVA - 0.75), [La] (ATIVA - 0.83, PASSIVA - 0.90) and FC (0.93) only for the passive group. Thus, it can be concluded that the cardiorrespiratory and metabolic responses present good realiability in an intermittent exercise with active or passive recovery

Interpretação da fadiga muscular por meio da eletromiografia durante corrida em esteira

O presente estudo teve como objetivo identificar a fadiga muscular por meio da amplitude e freqüência do sinal eletromiográfico (EMG) do músculo vasto lateral (VL) e reto femoral (RF) do membro inferior direito, durante protocolo incremental de corrida em esteira e nas contrações isométricas submáximas realizadas no início e após cada velocidade. Participaram deste estudo 07 voluntários saudáveis, do gênero masculino, experientes em corrida na esteira, com idade média de 25 anos (± 4,3), sem antecedentes de doenças músculo-esqueléticas nos membros inferiores e de antropometria semelhante. Foram realizadas três contrações isométricas voluntárias máximas (CIVM = 100%) de extensão do joelho para posterior determinação da contração submáxima de 50% da CIVM (CI-50%). O protocolo de corrida foi composto de um aquecimento de 5 minutos (9 km/h), e após iniciou-se o teste com velocidade inicial de 10 km/h e incremento de 1 km/h a cada 3 minutos, até a exaustão voluntária, havendo uma pausa entre cada velocidade de aproximadamente 2 minutos. Antes do início da corrida e após cada velocidade realizou-se uma contração isométrica com 50% da CIVM (CI-50%) de 5s de duração. No sinal eletromiográfico coletado durante a corrida, os valores de RMS (Root Mean Square) dos músculos VL e RF foram obtidos no período correspondente a um ciclo completo da passada a 10% e 100% do tempo analisado (120 segundos finais de cada velocidade) por meio de rotina específica (Matlab). No sinal eletromiográfico coletado durante as CI-50% (5s), os valores de RMS e FM (freqüência mediana) foram obtidos no período de 1s (intervalo de 1 a 2s). A normalidade dos dados foi determinada através do teste de Shapiro-Wilk. Utilizou-se teste-t de Student para amostras pareadas, e o nível de significância (p) adotado foi de p<0,05. Os resultados...(Resumo completo, clicar acesso eletrônico abaixo)

Análise de variáveis eletromiográficas e cinemáticas em protocolo incremental de corrida na esteira

Muscle fatigue is described as a cause of injuries among the many related to the running practice. Therefore, the purpose of this study was to analyze the behavior of the amplitude (RMS) and median frequency (MF) of EMG signal of the iliocostalis (CI), rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM) biceps femoris (long head) (BFCL), tibialis anterior (TA) and gastrocnemius (lateral) (LNG) from the right lower limb, and the behavior of the parameters of amplitude (AP) and frequency (PF) spent in different percentages of the maximum speed during incremental protocol of treadmill running. 10 volunteers participated in this study, athletes, male, aged between 18 and 30 years with no history of injury in lower limbs and similar anthropometry. The protocol consisted of a treadmill test with initial velocity of 10 km.h-¹ and increments of 1 km.h-¹ each three minutes until volitional exhaustion, without rest interval. Synchronized collections were made of electromyographic and kinematic data. The signals were obtained through an acquisition module of biological signals (Telemyo 900 - Noraxon - USA) and software (Myoresearch - Noraxon - USA) calibrated with a sampling frequency of 1000 Hz, gain 2000 times. The raw data were filtered with a 60Hz notch filter, high pass and low pass 20Hz to 500Hz. To capture the image was used a digital video recorder (model NV-GS320, PANASONIC brand), and for image scanning and kinematic data collection was used the software Peak Motus 9.0 (ViconPeak). To obtain the values of RMS and FM analyzed the last ten passes of each speed through a specific routine (Matlab). To obtain these variables AP (m) and FP (stride I min) were analyzed for the last ten past each speed, using specific software (Peak Motus 9.0). After verification of data normality (Shapiro-Wilk) and homogeneity of the data (Levene), the comparison ...(Complete abstract click electronic access below)

Efeito do exercício prévio na determinação da potência crítica

The objective of this study was to analyze the influence of previous exercise on the determination of critical power (CP). Seven apparently healthy nontrained males, of 18 to 25 years, participated of this study. The subjects were submitted, in different days to the following protocols in a cyclergometer: 1) one progressive test until voluntary exhaustion for the determination of lactate threshold (LL), maximal oxygen uptake (VO2max) and its corresponding intensity (IVO2max); 2) six constant workload tests at 95,100 and 110% IVO2max until exhaustion with and without a previous exercise at 70% , in random order. The exhaustion times (tlim) at 95, 100 and 110% IVO2max were adjusted forme thress models of two parameters to estimate CP and anaerobic work capacity (AWC) [P=CTAn/tlim)+CP; tlim = CTAn/(P-PC); P=PC.tlim+ CTAn]. The model with the lowest standard error was considered for the estimation of CP. The tlim at 95% IVO2max was similar without (501 ± 140 s) and with previous exercise (473 ± 99 s). However, the tlim at 100% (381 ± 103 s and 334 ± 101 s) and 110% IVO2max (267 ± 163 s and 227 ± 68 s) was significantly longer with previous exercise. There was no significant difference in CP and AWCat conditions without (200 ± 27 W and 23 ± 11 kJ, respectively) and with previous exercise (212 ± 30 W and 18 ± 8 kJ, respectively). It can be concluded that the parameters of the relationship between power and time were not modified by the previous severe exercise

Validação dos parâmetros aeróbio e anaeróbio a partir de protocolo não invasivo aplicado ao exercício resistido - supino reto

The purpose of this study was to investigate the validity of critical force test from maximal lactate steady state (MLSS) during resistance test using straight bench press. Five healthy male volunteers aged (22.6 ± 2.88 years), weight (76.3 ± 11.49 kg) e height (182.6 ± 7.54cm), trained in resistance exercise, and performed four diferent test to determine: one maximal effort (1RM), critical force using the critical power model (force vs 1/time limit - 20, 25 and 30% 1RM). The CF was the linear coefficient and the anaerobic impulse capacity (CIA) was the angular. MLSS was determined using loads of 80, 90, 100 and 110% of critical force. Blood lactate samples were abtained at each 300sec between each stage of total 1200sec. Maximal 30s test (M30) was accomplished with load of 25% of body weight in SBP. The results showed that the 1 RM was 79.4 Kgf (± 16.98), CF 10.1N (± 2.25), CIA 1756.82 N.s (± 546.96) and the R² 0.984 (± 0,02). The MLSS occurs at 100% CF load. The lactate concentration at the MLSS was 2.2 mmol/L (± 0.77). Significant correlation was observed between MLSS and CF on SBP (r = 0.88 p = 0.05). In M30 the minimum, mean and peak power were (25.0 ± 4.9, 28.0 ± 4.9, and 30.0 ± 4.6 kgf.rps, respectively). The fatigue index was 18.0% (± 6,8). The M30 was significantly correlated with Ppeak and Pmean (r = 0.98 for both, p = 0.003). The CF means has been validated to predict the resistance training and the CIA show to be a representative anaerobic parameter in straight bench press.

Efeito do pacing e do exercício prévio na performance aeróbia

The aim of this study was to analyze the influence of prior exercise on different intensity distribution strategies (pacing). The study included five male individuals, apparently healthy, aged between 18 and 25 years, and without regular practice of physical activities. The subjects were tested on different days following the protocols on a cycle ergometer: 1) a progressive ramp test, 2) three constant load tests in the intensities of 85%, 90% and 95% IVO2max to exhaustion, and 3) six tests with and without holding a prior exercise intensity of 70%  with different strategies for Even-intensity pace, ES (401 ± 70 W), which consists of an exercise at a pace and / or constant intensity from beginning to end; where intensity is initially increased to 10% less than the ES progressively increase to reach 10% above the intensity of ES, and; Fast-start; FS, where there is a reversal in the way of distributing intensity, ie the initial intensity is 10% higher than the value of ES decreased progressively to 10% below that ES. All these tests were performed in random order. The tlim with previous exercise was significantly shorter than without previous exercise at FS condition (p < 0.05). The VO2final obtained at ES condition was similar with (3243 ± 599 ml.min-1) and without (3252 ± 384 ml.min-1) previous aerobic exercise (p > 0.05). However, the VO2final obtained at FS condition was higher with (3291 ± 218 ml.min-1) than without (3097 ± 207 ml.min-1) previous aerobic exercise (p < 0.05). The heart rate was higher at ES condition with than without previous aerobic exercise (p < 0.05). There was no significant difference in this variable for FS condition with and without previous aerobic exercise (p > 0.05). It can be concluded that the results the previous exercise (70%) achieved lasting 6 minutes followed by 6 minutes of recovery appears to influence / commit ting the conditions during the pacing for this population

Modelagem de motor de combustão internae simulação do processo de queima de combustível

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

Efeito da recuperação ativa na determinação da máxima fase estável de lactato sanguíneo no ciclismo

The objective of this study was to compare the power corresponding to maximal lactate steady state determined through continuous (MLSSC) and intermittent protocol with active recovery (MLSSI). Ten trained male cyclists (25 ± 4 yr, 72.5 ± 10.6 kg, 178.5 ± 4.0 cm), performed the following tests on different days on a cycle ergometer: (1) incremental test in order to determine the anaerobic threshold (AT) and maximal power (Pmax); (2) two to five constant workload tests to determine MLSSC, and; 3) two to three constant workload tests to determine MLSSI, consisting on 8 x 4 minutes bouts interspersed by two minutes of active recovery at 50% Pmax (i.e., 46 min of exercise protocol). MLSS intensity was defined as the highest workload at which blood lactate concentration did not increase by more than 1 mM between minutes 10 and 30 of the constant workload. The workload corresponding to MLSSC (273.2 ± 21.4 W) was significantly lower than that corresponding to MLSSI (300.5 ± 23.9 W). With base on these data, it can be verified that the intermittent exercise mode utilized in this study, allows an increase of 10% approximately, in the exercise intensity corresponding to MLSS.

Efeito da manipulação do feedback da percepção subjetiva de esforço esperada na percepção subjetiva de esforço e no desempenho de adultos de diferentes faixas etárias

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo sobre uma turbina a gás instalada em uma refinaria de petróleo

The gas turbine (GT) is known to have: low cost of capital over the amount of energy, high flexibility, high reliability, short delivery time, commissioning and commercial operation at the beginning and quick departure. The gas turbine is also recognized for its superior environmental performance, manifested in air pollution containment and reducing greenhouse gases (Mahi, 1994). Gas turbines in simple cycle mode (SC) have long been used by utilities to limited power generation peak. In addition, manufacturing facilities use gas turbines for power generation units on site, often in combination with the process of heat production, such as hot water and steam process. In recent years, the performance of industrial gas turbines has been improved due to significant investments in research and development, in terms of fuel to electricity conversion efficiency, plant capacity, availability and reliability. The greater availability of energy resources such as natural gas (NG), the significant reduction of capital costs and the introduction of advanced cycles, have also been a success factor for the increased use of gas turbines to load applications base (Poulikas, 2004). Open Cycle Gas Turbine with a greater degree of heat to the atmosphere may alternatively be used to produce additional electricity using a steam cycle, or to compose a cogeneration process. The combined cycle (CC) uses the heat from the gas turbine exhaust gas to increase the power output and increase the overall efficiency of more than 50% second (Najjar, 2001). The initial discovery of these cycles in the commercial power generation market was possible due to the development of the gas turbine. Only from the 1970s that gas turbine inlet temperature and therefore the exhaust gas temperature was sufficiently high to allow a better efficiency in the combined cycle ... (Complete Abstract click electronic access below)