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Search Results: 1 - 10 of 118043 matches for " Lincoln Cardoso Brand?o "
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TEMPERATURE AND HEAT FLOW WHEN TAPPING OF THE HARDENED STEEL USING DIFFERENT COOLING SYSTEMS
Cardoso Brando,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 Brando,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
Evaluation of Hole Quality in Hardened Steel with High-Speed Drilling Using Different Cooling Systems
Lincoln Cardoso Brando,Frederico Ozanan Neves,Gregório Christo Nocelli
Advances in Mechanical Engineering , 2011, DOI: 10.1155/2011/746535
Abstract: This work evaluates the hole quality on AISI H13 hardened steel using high-speed drilling. Specimens were machined with new and worn out drills with 8.6?mm diameter and (TiAl)N coating. Two levels of cutting speed and three levels of cooling/lubrication systems (flooded, minimum lubrication quantity, and dry) were used. The hole quality is evaluated on surface roughness (Ra) parameter, diameter error, circularity, and cylindricity error. A statistical analysis of the results shows that the cooling/lubrication system significantly affects the hole quality for all measured variables. This analysis indicates that dry machining produces the worst results. Higher cutting speeds not only prove beneficial to diameter error and circularity errors, but also show no significant difference on surface roughness and cylindricity errors. The effects of the interaction between the cooling/lubrication systems, tool wear, and cutting speed indicate that only cylindricity error is influenced. Thus, the conclusion is that the best hole quality is produced with a higher cutting speed using flooded or minimum lubrication quantity independent of drill wear. 1. Introduction Nowadays, the molds and dies industries are very important in the supply chain to obtain a new product at low costs. In addition, considering industrial competitiveness and short product life, the requirements on production times and lower costs of machining processes are of significant importance. One should also consider that drilling is an especially extreme process in most industries, which use conventional machine tools the majority of times. When the production of molds and dies is considered, the machining process corresponds to 65% of the costs and drilling is the most utilized process. According to Haber-Haber et al. [1], drilling is one of the main machining operations in the manufacturing industry, and in some countries drilling has been reported to account for nearly 50% of all machining operations. That is why it is important to study drilling performance with strong reduction or total elimination of cooling systems, considering the aspects of tool life. Cooling fluids are very important in high-speed cutting where the temperature can approach annealing point. Heat generation and friction between the tool and chip generally limit drilling performance, therefore coolants and lubricants are used in high quantities to reduce the temperature and friction in the cutting region [2]. On the other hand, vapors generated during the machining process are prejudicial to the operator’s health, and much
Experimental and theoretical study on workpiece temperature when tapping hardened AISI H13 using different cooling systems
Brando, 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.
Writing and Publishing Scientific Articles in Computer Science
Wladmir Cardoso Brando
Computer Science , 2015,
Abstract: Over 15 years of teaching, advising students and coordinating scientific research activities and projects in computer science, we have observed the difficulties of students to write scientific papers to present the results of their research practices. In addition, they repeatedly have doubts about the publishing process. In this article we propose a conceptual framework to support the writing and publishing of scientific papers in computer science, providing a kind of guide for computer science students to effectively present the results of their research practices, particularly for experimental research.
Community-Acquired Severe Sepsis: A Prospective Cohort Study  [PDF]
Cristiana Sousa, Mariana Brando, Orquídea Ribeiro, Teresa Cardoso
Open Journal of Internal Medicine (OJIM) , 2015, DOI: 10.4236/ojim.2015.53008
Abstract: Severe sepsis (SS) is one of the principal causes of admission in intensive care units (ICU), with an associated high morbidity and mortality. This study intends to characterize epidemiology of community-acquired SS (CASS) with special emphasis in the prevalence of multidrug resistant organisms and independent prognostic factors associated with ICU mortality. Methods: A prospective cohort study was conducted over 3.5 years, including all consecutive adult patients with CASS admitted to a mixed ICU, in a 600-bed university-affiliated hospital. Results: 1221 patients were admitted into the ICU, 25% with CASS. The mean age was 59 years and the mean SAPS (simplified acute physiological score) was II 48. Most had septic shock (67%). Respiratory (57%), intra-abdominal (22%) and urinary tract (8%) infections were the main sources of infection. The overall isolation rate was 56%. The most common identified microorganisms were Streptococcus pneumoniae (27%), Escherichia coli (22%), Staphylococcus aureus methicillin sensitive (8%) and Haemophilus influenzae (7%). The median ICU and hospital length of stay were 8 and 16 days, respectively. The ICU mortality rate was 33. Independent risk factors associated with higher mortality were older age, higher SAPS II, septic shock and chronic hepatic disease. Female gender was independently associated with lower mortality. The type of microorganism was not significantly associated with prognosis. Conclusion: CASS was highly prevalent among ICU admissions. Independent risk factors associated with ICU mortality included older age and previous comorbidities, but mainly severity of acute illness reinforcing the need for early recognition and treatment. Multidrug resistant organisms were implicated in considerable proportion of community-acquired sepsis.
Turning hardened steel using coated carbide at high cutting speeds
Aneiro, Federico M.;Coelho, Reginaldo T.;Brando, 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.
Analysis of automotive liftgate seals using finite element analysis
Ueda, Rafael H. T;Brando, Lincoln C;Lauro, Carlos H;
Polímeros , 2010, DOI: 10.1590/S0104-14282010005000052
Abstract: seals have wide application in automotive products. they are responsible for sealing the car in several parts such as the doors, the air intake cowl seal, and air intake lights seal. strain and stress studies are very important in order to understand the behavior of polymeric materials, which are generally submitted to great workload variation and environmental influence. this study of epdm rubber was carried out to define the strain, stress and yield stress. tensile and compression tests were carried out on workpieces with 100 mm of length. the data were acquired using the qmat software. a finite element analysis using the msc marc mentattm was conducted and compared with experimental tests. the results showed an increase of effort proportional to bulb thickness. the proportional increase of compression effort for different displacements was significant. moreover, physical parameters such as length, thickness, and friction coefficient changed the strain and stress rate.
Nitric oxide alteration in the cardiovascular function by exercise training Altera o do óxido nítrico na fun o cardiovascular pelo treinamento físico
Arthur de Freitas Brando,Marli Cardoso Martins Pinge
Semina : Ciências Biológicas e da Saúde , 2007,
Abstract: Among the mechanisms of arterial pressure control, the humoral one carried out by the nitric oxide (NO) has aroused great scientific interest. The cardiovascular effects observed after the physical training are associated to an increase in the vascular structure, resting bradycardia and a post effort hypotension effect. The NO that is synthesized in endothelial cells from the L-arginine amino acid with the nitric oxide synthase (NOS) action is considered a powerful vaso-dilator. The NO has three enzymatic isoforms: the nNOS enzyme is present in the nervous cells, and the eNOS in the endothelial cells, both calciumdependent. On the other hand, the iNOS which is activated by immunological stimuli, is calciumindependent. In the central nervous system (CNS), the NO exerts an important role in the blood pressure control through sympathetic nervous system, inhibiting its activity and decreasing the vascular tonus. Moreover, the NO exerts an influence on the rostral ventrolateral medulla (RVLM), which is important in the modulation of the cardiovascular function. Studies that relate physical training and NO, noticed a significant increase in vasodilation after physical training in special population such as: hypertensives, obese, diabetic and cardiopath people, when compared with healthy individuals. In this sense, there seems to be a modulation of the physical training on the NO participation in the PA control, not only in the peripherical but also in the central level. New studies are still necessary to better elucidate this phenomenon. Dentre os mecanismos de controle da press o arterial, o controle humoral realizado pelo óxido nítrico (NO) tem despertado grande interesse científico. Os efeitos cardiovasculares observados após o treinamento físico est o associados ao aumento da estrutura vascular, bradicardia de repouso e um efeito hipotensor após esfor o. O NO, sintetizado em células endoteliais a partir do aminoácido Larginina com a a o da enzima óxido nítrico sintase (NOS), é considerado um potente vasodilatador. O NO possui três isoformas enzimáticas: a enzima nNOS atua nas células nervosas e a eNOS em células endoteliais (ambas cálcio dependentes) e a iNOS, é ativada por estímulos imunológicos e independente do íon cálcio. No sistema nervoso central (SNC), o NO possui importante papel no controle da press o sanguínea via sistema nervoso simpático, pois inibe sua atividade e diminui seu t nus sobre os vasos. Além disso, o NO exerce influência na regi o ventrolateral rostral medular (RVLM), importante na modula o da fun o cardiovascular. Estudos que r
Análise econ?mica preliminar de uma unidade de resfriamento a vácuo de alface
Cortez, Luís A.B.;Neves Filho, Lincoln C.;Cardoso, Jo?o L.;
Horticultura Brasileira , 2000, DOI: 10.1590/S0102-05362000000300019
Abstract: this paper presents an economic analyzes of a vacuum pre-cooling unit for lettuce in brazil. the fixed and local operational costs were considered and the benefits derived from the investment were quantified considering the actual losses of horticultural products. the obtained results indicate a satisfactory period of return for the project (less than 1 year) although the investment is considered quite high.
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