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Search Results: 1 - 10 of 12980 matches for " Lincoln; Teixeira Coelho "
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TEMPERATURE AND HEAT FLOW WHEN TAPPING OF THE HARDENED STEEL USING DIFFERENT COOLING SYSTEMS
Cardoso Brand?o,Lincoln; Teixeira Coelho,Reginaldo;
Ingeniare. Revista chilena de ingeniería , 2009, DOI: 10.4067/S0718-33052009000200015
Abstract: machining hardened steels has always been a great challenge in metal cutting, particularly for tapping operations. in the present paper, temperature was assessed when tapping hardened aisi h13. dry machining and two cooling/lubrication systems were used: flooded and minimum quantity of fluid (mqf) with 20ml/h, both using mineral oil. the tapping operation was performed on 100 x 40 mm, 14 mm thick workpieces with 55 hrc. an implanted thermocouple technique was used for temperature measurement at distances very close to the highest thread diameter (at 0.1, 2.5 and 5.0 mm). three thermocouples were used for each distance along the workpiece diameter at 3.0, 7.0 and 11.0 mm from the tap entrance. measurements were replicated twice for each condition tested. an analytical theoretical heat conduction model was used to evaluate the temperature at the tool-workpiece interface and determine the heat flow and convection coefficient. the smallest temperature increase and heat flow were observed when using the flooded system, followed by the mqf, compared to the dry condition. the effect was directly proportional to the amount of lubricant applied, as well as with the mqf system, when compared to dry cutting.
TEMPERATURE AND HEAT FLOW WHEN TAPPING OF THE HARDENED STEEL USING DIFFERENT COOLING SYSTEMS TEMPERATURA Y FLUJO DE CALOR AL ROSCAR CON MACHOS ACERO ENDURECIDO UTILIZANDO DIVERSOS SISTEMAS DE LUBRICACIóN
Lincoln Cardoso Brand?o,Reginaldo Teixeira Coelho
Ingeniare : Revista Chilena de Ingeniería , 2009,
Abstract: Machining hardened steels has always been a great challenge in metal cutting, particularly for tapping operations. In the present paper, temperature was assessed when tapping hardened AISI H13. Dry machining and two cooling/lubrication systems were used: flooded and minimum quantity of fluid (MQF) with 20ml/h, both using mineral oil. The tapping operation was performed on 100 x 40 mm, 14 mm thick workpieces with 55 HRc. An implanted thermocouple technique was used for temperature measurement at distances very close to the highest thread diameter (at 0.1, 2.5 and 5.0 mm). Three thermocouples were used for each distance along the workpiece diameter at 3.0, 7.0 and 11.0 mm from the tap entrance. Measurements were replicated twice for each condition tested. An analytical theoretical heat conduction model was used to evaluate the temperature at the tool-workpiece interface and determine the heat flow and convection coefficient. The smallest temperature increase and heat flow were observed when using the flooded system, followed by the MQF, compared to the dry condition. The effect was directly proportional to the amount of lubricant applied, as well as with the MQF system, when compared to dry cutting. Trabajar los aceros endurecidos siempre ha sido un desafío para el corte de metales, particularmente en las operaciones de roscado. En el presente trabajo se mide la temperatura del acero AISI H13 endurecido, realizándose ensayos sin lubricación (seco) y dos sistemas con lubricación: aceite lubricante en grandes cantidades y mínima cantidad de líquido (minimum quantity of fluid MQF) a 20 ml/h, en ambos casos se utilizó aceite integral mineral. El roscado se realiza sobre probetas de prueba de 100 x 40 mm con 14mm de espesor y dureza de 55 HRc. Para medir la temperatura se utiliza la técnica de termocuplas situadas muy próximas al diámetro mayor del hilo de rosca (a 0.1, 2.5 y 5 mm de distancia). Se utiliza tres termocuplas a lo largo del espesor de la probeta de prueba a 3.0, 7.0 y 11.0 mm desde la entrada del roscado. Se hacen dos réplicas del registro de la temperatura para cada condición de corte ensayada. Se utilizan un modelo teórico-analítico de conducción de calor para evaluar la temperatura en la interfase de la probeta de prueba, determinar el flujo de calor y el coeficiente de convección. El menor incremento de la temperatura y del calor se observa al utilizar el método lubricante en grandes cantidades, seguido por el de MQF, al comparar con la condición en seco. El efecto es directamente proporcional a la cantidad de lubricante aplicado, siendo tamb
Experimental and theoretical study on workpiece temperature when tapping hardened AISI H13 using different cooling systems
Brand?o, Lincoln Cardoso;Coelho, Reginaldo Teixeira;Malavolta, Alexandre Tácito;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2010, DOI: 10.1590/S1678-58782010000200008
Abstract: tapping operations on hardened steels have always been a great challenge. dry machining and two cooling systems were used when tapping hardened aisi h13 (53 hrc). embedded thermocouples were used for temperature measurement close to the thread diameter in the radial and axial direction. a fea model was used to evaluate the heat "q", and coefficient of convection "h". the lowest temperature peak occurred with the flooded system, followed by the mql, and dry condition. the heat and coefficient of convection increased when using the flooded system, followed by the mql, compared to the dry condition. those values were also in accordance with early published works, using different techniques.
Pesquisa de óxido Nítrico no Fluido Peritoneal e no Soro de Pacientes com Endometriose
Coelho Rogéria Teixeira
Revista Brasileira de Ginecologia e Obstetrícia , 2002,
Abstract:
EFEITO DO ARMAZENAMENTO DE HASTES DE LARANJA CACAU (Citrus sinensis Osb) NO "PEGAMENTO" DE BORBULHAS EFFECT OF THE STORAGE PERIOD OF “CACAU” ORANGE (Citrus sinensis OSB) BUDWOODS ON THE QUALITY OF BUDS FOR GRAFTING
Maria Terezinha Teixeira Lopes,Lincoln F. Zica
Pesquisa Agropecuária Tropical , 2007, DOI: 10.5216/pat.v4i1.2154
Abstract: O presente trabalho foi realizado na Escola de Agronomia e Veterinária da UFGO, com o objetivo de estudar o efeito da conserva o de borbulhas de laranja “Cacau” (Citrus sinensis Osb) embaladas em sacos plásticos, no pegamento de enxertos. Os tratamentos utilizados foram enxertia com borbulhas de hastes com 0, 5, 10, 15 e 20 dias de conserva o. A percentagem de enxertos brotados decresceu linearmente em fun o do período de conserva o. à medida que aumentava a intensidade de descolora o das hastes, diminuía a percentagem de "pegamento" de enxertos. Para nossas condi es as borbulhas de laranja "cacau" (Citrus sinensis Osb) n o devem ser conservadas em sacos plásticos, à temperatura ambiente, por mais de 5 dias, pois a percentagem de enxertos brotados decresceu linearmente com o período de conserva o das hastes. This work was carried out at the Escola de Agronomia e Veterinária da UFGO. This study was made to test the effect of the storage period of the “cacau” orange budwood on the quality of buds for grafting. Budwoods of the “Cacau” orange (Citrus sinensis Osb) were harvested, packed in polyethylene bags and maintained at environmental temperature. The buds were grafted on rootstocks of Rangpur lime (Citrus limonia, Osb) at intervals of 6 days (0, 5, 10, 15 and 20 days). It was noted that the loss of bud viability increased simultaneously with progressive change in budwood color from the natural green to an intense brown. The percentages of buds alive after 60 days of grafting were: 100% on the day budwoods were harvested; 70% after 5 days of storage; 36% after 10 days of storage and 00% after 15 days.
Turning hardened steel using coated carbide at high cutting speeds
Aneiro, Federico M.;Coelho, Reginaldo T.;Brand?o, Lincoln C.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2008, DOI: 10.1590/S1678-58782008000200002
Abstract: the present work studies some aspects of the turning process applied on hardened steel using multilayer coated carbide tools at high cutting speeds. the influence of cutting parameters (vc, f, and depth of cut - d.o.c.) on tool temperature, tool wear, cutting forces, and surface roughness were analyzed. the current literature reports many studies using pcbn on hardened steel, but it is also important to know the results when using coated carbide tools, mainly for economical reasons. temperature was measured by a thermocouple positioned at the lowest insert face, underneath it. temperature near the rake face was calculated using the measured gradient within the insert thickness. to measure the gradient a special technique was used with one embedded thermocouple near the rake face and one underneath. tool wear measurements demonstrated the capability of such tools in turning hardened steel with reasonable tool life. forces measured resulted in relatively low values, being the radial component the largest of all. for the different cutting conditions studied, the doc has the greatest influence on force and temperature. additionally, the best surface roughness values were smaller than 0,4 μm ra.
Spirituality in a secular age: From Charles Taylor to study of the Bible and spirituality
AT Lincoln
Acta Theologica , 2011,
Abstract: This essay proposes that those engaged in the study of the Bible in relation to spirituality would benefit from awareness of Charles Taylor’s thinking in A Secular Age, which is a narrative not only about the emergence of the secular but also about the role of the spiritual in Western civilization. The essay indicates the significance of Taylor’s work for understanding the present context of the experience of spirituality. It then suggests some possible implications for how biblical perspectives on spirituality might be studied, highlighting Taylor’s category of the social imaginary. Finally, it reflects on the potential of Taylor’s work for those who are interested in dialogue between a spirituality rooted in biblical perspectives and contemporary forms of spirituality, focusing on his notion of “fullness.”
Desenvolvimento e calibra??o de um tensi?metro eletr?nico de leitura automática
Teixeira, Adunias S.;Coelho, Silvana L.;
Engenharia Agrícola , 2005, DOI: 10.1590/S0100-69162005000200010
Abstract: this paper presents the development and calibration of a tensiometer for automatic reading where mercury has been replaced by an electronic pressure sensor called the electronic tensiometer. the conventional mercury tensiometer was used as a standard for calibration. calibration trials were conducted at the mechanics and electronics laboratory of the department of agricultural engineering at ceará federal university, brazil. the electronic tensiometer outputs a maximum 4.5 volts and is connected to a data acquisition system (daq) composed of a microprocessor, a 12-bit analog to digital converter and a serial port. the daq outputs to a microcomputer via a serial port. the trial bench was made of three hard plastic boxes filled with sandy-loam soil. calibration trials have run for a month and linear calibration equations of the form count = offset + aym, were obtained, where ym represents the soil-water matric potential read at the conventional mercury tensiometer (kpa) and count, the digital output from the electronic tensiometer, with dimensionless values ranging from 0 to 4,095. maximum and minimum values of 348.572 and 261.026 were obtained for the offset, and 36.675 kpa-1 e 34.421 kpa-1 for the angular coefficient. statistical analysis on the offset and coefficients of the calibration equations indicated that exists a significance confidence lower than 0.1% and correlation coefficients of at least 0.9994 for any of the nine sensors tested.
Avalia??o do tensi?metro eletr?nico no monitoramento do potencial matricial de água no solo
Coelho, Silvana L.;Teixeira, Adunias dos S.;
Engenharia Agrícola , 2004, DOI: 10.1590/S0100-69162004000300006
Abstract: this paper presents the monitoring of the soil matrix potential using the electronic tensiometer. the trials were conducted at the mechanics and electronics lab of the department of agricultural engineering of the federal university of ceara. nine samples of electronic tensiometers and three conventional mercury tensiometers were tested for a month period of data gathered at a 2 hz frequency. the monitoring made it possible to produce insights on the soil drying process, on the effect of temperature fluctuation on the readings, and it was possible to evaluate the response time and sensitivity of the electronic tensiometer. it was found that the temperature effect on the readings increases as the matrix potential decreases, thus it is essential to install temperature sensors on the electronic tensiometers in order to remove the errors induced by temperature variation especially if the sensors are to be used at the peak hours. the response time increases as the matrix potential decreases and the tensiometers tested presented average sensitivity of 42.833 mv(kpa)-1, and precision of 0.02334 kpa or 0.2380 cm c h2o.
Impactos na produ??o de políticas "desacopladas" na agricultura norte-americana: o papel do risco
Coelho, Alexandre Bragan?a;Teixeira, Erly Cardoso;
Revista de Economia e Sociologia Rural , 2005, DOI: 10.1590/S0103-20032005000200001
Abstract: in the last few years, efforts have been made to modify agricultural support policies in order to minimize the distortive impacts on product level and on international trade. emphasis has been given to decoupled payments, considered neutral to current production decisions. the main argument is that such payments do not influence the crop marginal returns because they are not based on current production. this article shows, however, that current production decisions are influenced by decoupled payments through direct impacts on risk perception by farmers. these effects, classified as income effect and insurance effect, stimulate the increase in planted area and, therefore, have impacts on production and price levels.
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