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Search Results: 1 - 10 of 72228 matches for " Eduardo Carlos;Aguiar "
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Using the Sound Card as a Timer
Carlos Eduardo Aguiar,Marta Maximo Pereira
Physics , 2009, DOI: 10.1119/1.3527753
Abstract: Experiments in mechanics can often be timed by the sounds they produce. In such cases, digital audio recordings provide a simple way of measuring time intervals with an accuracy comparable to that of photogate timers. We illustrate this with an experiment in the physics of sports: to measure the speed of a hard-kicked soccer ball.
Google Earth Physics
Carlos Eduardo Aguiar,Anderson Ribeiro de Souza
Physics , 2009, DOI: 10.1088/0031-9120/44/6/009
Abstract: Google Earth photographs often show ships and their wakes in great detail. We discuss how the images can be used to calculate the velocity of these ships.
Uma atualiza??o da lista de Cladocera Cladocera (Crustacea, Branchiopoda) do Estado de Pernambuco, Brasil
Soares, Carlos Eduardo Aguiar;Elmoor-Loureiro, Lourdes Maria Abdu;
Biota Neotropica , 2011, DOI: 10.1590/S1676-06032011000200038
Abstract: the present study aimed to identify the cladocera species present in 15 samples of zooplankton, taken occasionally between 1981 and 2001, from the counties of recife, jaboat?o dos guararapes, paulista e escada (state of pernambuco, brazil). in total, 32 species were reported; 10 of them represent first records, which increased to 51 the number of species known to occur in pernambuco state. the highest cladoceran species richness was observed in water bodies where macrophytes were more abundant and with more samples available.
Determination of the momentum of droplets impinging on the pool during aluminium GMAW
Scotti, Américo;Rodrigues, Carlos Eduardo Aguiar Lima;
Soldagem & Inspe??o , 2009, DOI: 10.1590/S0104-92242009000400008
Abstract: the purpose of this work was to raise the kinematics and dynamics characteristics of the droplets under transference during aluminium gma welding and quantify the partial effect of the momentum on the weld bead formation. it is initially claimed that a better way of quantifying this effect would be through the mass flow rate of the droplets reaching the weld pool; calculated parameter denominated here as effective momentum. bead-on-plate gmaw, shielded with ar, was carried out using an aluminium alloy wire. three levels of current and two levels of arc length were employed in the experimental design. high-speed filming shadowgraphy, synchronized with the electrical signals, was used as measuring tool. dedicated computational programs were employed to quantify arc lengths and size, frequency, acceleration and speed of the droplets. it was confirmed that in spite of the low values of the effective momentum for aluminium gmaw, the momentum is one of the governing factor in developing bead penetration. the interaction between effective momentum and welding current and its effect on the aluminium gmaw bead geometry is discussed.
Studies on the cooling minimum quantity and conventional cooling at hardened steels in grinding process
Aguiar, Paulo Roberto de;Catai, Rodrigo Eduardo;Bianchi, Eduardo Carlos;Freitas, Roberto de;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2007, DOI: 10.1590/S1678-58782007000200002
Abstract: the purpose of this work is to explain the concept of cutting fluids reasonable usage through the fluid minimum quantity in grinding processes. on that purpose, the development of a new nozzle and an own and adequate methodology should be required in order to obtain good results and compare them to the conventional methods. the analysis of the grinding wheel/cutting fluid performance was accomplished from the following input parameters: flow rate variation by nozzle diameter changes (three diameters values: 3mm, 4mm and 5mm), besides the conventional round nozzle already within the machine. integral oil and a synthetic emulsion were used as cutting fluids and a conventional grinding wheel was employed. the workpieces were made of steel vc 131, tempered and quenched with 60hrc. thus, as the flow rate and the nozzle diameter changes, keeping steady fluid jet velocity (equal to cutting velocity), attempted to find the best machining conditions, with the purpose to obtain a decrease on the cutting fluid volume, taking into consideration the analysis of the process output variables such as cutting strength, cutting specific energy, grinding wheel wear and surface roughness. it was verified that the 3mm diameter optimized nozzle and the integral oil, in general, was the best combination among all proposed.
Analysis of the influence of infeed rate and cutting fluid on cylindrical grinding processes using a conventional wheel
Bianchi, Eduardo Carlos;Franzo, Carolina Grimm;Aguiar, Paulo Roberto de;Catai, Rodrigo Eduardo;
Materials Research , 2004, DOI: 10.1590/S1516-14392004000300004
Abstract: new worldwide trends such as globalization have rendered grinding processes increasingly important for industry, making it essential to perform in-depth studies of variations in grinding process parameters in the pursuit of greater cost effectiveness. this paper presents a comparative analysis of three different infeed rates, using a conventional grinding wheel on quenched and tempered d2 steel workpieces. higher infeed rates are known to be correlated with shorter grinding times, rendering the process more economically attractive. two different coolant fluids, 5% emulsion and pure oil, were used. the tests were carried out using the smallest possible amount of coolant and an optimized 5 mm diameter nozzle. the parameters analyzed were tangential force, specific energy, acoustic emission, roundness error and surface roughness. the surfaces of the workpieces were also examined by scanning electron microscopy (sem). the results revealed that increased infeed rates could reduce processing times without compromising the quality of the workpiece profile, thereby reducing the cost of the process. the best cutting fluid, albeit more harmful to human health and less environmentally friendly, was found to be pure oil.
A comparison between sphygmomanometer-based and ambulatory blood pressure monitoring in acute salt loading and depletion protocol
Paiva, Carlos Eduardo;Aguiar, Andréia Fernanda Carvalho Leone;Nobre, Fernando;Coelho, Eduardo Barbosa;
Clinics , 2011, DOI: 10.1590/S1807-59322011000500010
Abstract: introduction: ambulatory blood pressure monitors have been used in salt loading and depletion protocols. however, the agreement between measurements made using ambulatory blood pressure monitors and those made with the sphygmomanometer has not been evaluated. objective: the objective of this study was to compare the concordance of the two methods of blood pressure measurements in protocols of acute salt loading and depletion. method: systolic blood pressure was measured using a sphygmomanometer at the completion of salt infusion (2 l nacl 0.9%, 4 h) and salt depletion (furosemide, 120mg/day, p.o.) in 18 volunteers. using the pearson correlation coefficient (ρ), these readings were compared with the mean systolic blood pressure measured using the ambulatory blood pressure monitoring device during the following periods: 4 h of saline infusion and 12 h of salt depletion; 4 h of saline infusion and the last 6 h of salt depletion; 12 h of salt loading and the last 6 h of depletion; 12 h of salt loading and 12 h of depletion. salt sensitivity was defined by a difference in the systolic blood pressure between salt loading and salt depletion greater than 10 mmhg when measured with the sphygmomanometer, and the kappa analysis of concordance (k) was used with a significance level of p<0.05. results: only the blood pressure readings obtained using the ambulatory blood pressure device during 4 h of intravenous nacl and during 12 h of salt depletion showed a high correlation with the variation in the systolic blood pressure measured by the sphygmomanometer, with a full agreement with the salt sensitivity classification (p = 0.71; p = 0.001 and k=1). conclusion: in acute salt loading and depletion protocols, an ambulatory blood pressure monitoring device should be used to record the blood pressure during the 4-h interval of salt infusion and 12-h interval of salt depletion.
Influência na qualidade final de metais retificados através da varia??o da velocidade de mergulho
Alves, Manoel Cleber Sampaio;Bianchi, Eduardo Carlos;Aguiar, Paulo Roberto de;Catai, Rodrigo Eduardo;
Rem: Revista Escola de Minas , 2009, DOI: 10.1590/S0370-44672009000100010
Abstract: grinding, the final stage of the machining process, employs a significant amount of cutting fluids for lubrication, cooling and swarf removal. however, these cutting fluids are extremely aggressive to the environment. with technological progress, the world tendency is to produce more and more sophisticated pieces,having a high degree of geometrical and dimensional tolerance, good surface finish, hlow cost and, mainly, insignificant impact on the environment. therefore, recycling cutting fluids is intrinsic and cost-cutting for the grinding process and this work aimed to assess several output parameters in external cylindrical grinding: tangential force, acoustic emission, surface roughness, roundness, tool wear, and residual stress. also, analysis of microstructural features through scanning electron microscopy (sem) was carried out. tests was developed for abnt d6 steel, using a cbn grinding wheel with vitrified bond and two types of cutting fluids analyzing cutting fluid performance, grinding wheel time and feed rate, the best grinding conditions were found, leading to a decrease in cutting fluid volume and grinding time without impairing the geometrical and dimensional parameters, surface finish and surface integrity of the parts.
Evaluation of the thermal damages in inlet engine valves varying the grinding wheels and the cutting fluids
Bianchi, Eduardo Carlos;Silva, Eraldo Janonne da;Aguiar, Paulo Roberto de;Catai, Rodrigo Eduardo;
Rem: Revista Escola de Minas , 2003, DOI: 10.1590/S0370-44672003000200003
Abstract: this paper presents an experimental research in which the thermal damage in inlet engine valves grinding was evaluated. four different cutting fluids and two grinding wheel were tested and were analyzed the workpiece residual stress, the micro hardness and the optical observation of the workpiece microstructure. the cutting fluid and the grinding wheel types adopted resulted in different types of residual stress. the cutting oil resulted in compressive residual stresses, even using the conventional wheel. the cbn wheel, due to the best proprieties of its grains resulted in compressive residual stresses for all fluids tested by the reducing of the grinding energy and its easier dissipation from the grinding zone. the microstructure investigations showed that the source of the tensile residual stresses observed was the thermal cycles imposed. no microstructure alterations were detected. although, the absence of microstructure alterations not always suggests that favorable residual stresses can be obtained.
Analysis of the influence of infeed rate and cutting fluid on cylindrical grinding processes using a conventional wheel
Bianchi Eduardo Carlos,Franzo Carolina Grimm,Aguiar Paulo Roberto de,Catai Rodrigo Eduardo
Materials Research , 2004,
Abstract: New worldwide trends such as globalization have rendered grinding processes increasingly important for industry, making it essential to perform in-depth studies of variations in grinding process parameters in the pursuit of greater cost effectiveness. This paper presents a comparative analysis of three different infeed rates, using a conventional grinding wheel on quenched and tempered D2 steel workpieces. Higher infeed rates are known to be correlated with shorter grinding times, rendering the process more economically attractive. Two different coolant fluids, 5% emulsion and pure oil, were used. The tests were carried out using the smallest possible amount of coolant and an optimized 5 mm diameter nozzle. The parameters analyzed were tangential force, specific energy, acoustic emission, roundness error and surface roughness. The surfaces of the workpieces were also examined by scanning electron microscopy (SEM). The results revealed that increased infeed rates could reduce processing times without compromising the quality of the workpiece profile, thereby reducing the cost of the process. The best cutting fluid, albeit more harmful to human health and less environmentally friendly, was found to be pure oil.
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