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Comportamiento del tiempo de duración, la frecuencia de los cortocircuitos y la conductividad eléctrica durante el reencendido del arco en la soldadura SMAW (AC) con electrodos E6013
García Rodríguez, Alejandro;Gómez Pérez, Carlos René;Rivera Borroto, Oscar Miguel;Miguel Oria, Jorge Víctor;
Soldagem & Inspe??o , 2009, DOI: 10.1590/S0104-92242009000100008
Abstract: the objective of this work is the valuation of the behavior of short-circuits frequency and duration time and electrical conductivity on arc reigniting in smaw (shielded metal arc welding) process with alternate current and e6013 electrodes. the non parametric statistic analysis realize a robust data processing, minimizing the outliers influence and mistakes derivates about employ of approximations to well know continues distributions. the median and the median absolute deviation (mad) respect to median of the data are the localization and dispersion estimators used, respectively. the electrode at 160 a present a better stability on metal transference supported on the most little value of mad for the period of transference (39,36 ms), and the mad of the short-circuit duration (1,43 ms), according with the presence of a major electric conductivity during the arc reigniting (1766,17x10-3 s?s-1).
Valoración del desempe?o de un dispositivo de autoalimentación dise?ado para la evaluación operativa de electrodos revestidos
García Rodríguez, Alejandro;Gómez Pérez, Carlos René;Miguel Oria, Jorge Víctor;Rivera Borroto, Oscar Miguel;Sánchez Roca, Angel;
Soldagem & Inspe??o , 2009, DOI: 10.1590/S0104-92242009000100007
Abstract: the objective of the present work is to evaluate the effectiveness of a self-feed device for covered electrodes. this device is able of eliminate disturbances from manual operation or the use of automatic control systems during the study of covered electrode behavior. the conjugation of different methods like short-circuit time statistical analysis, metallographic analysis (penetration, heat affected zone, shape and mean distance between successive solidification fronts) together with the analysis of the electric arc and electrode melting parameters allow us to obtain relationships between arc behavior, mass transfer processes and bead appearance. this permits the extraction of criteria to describe process stability and the behavior of the feed device employed. an appropriate statistical methodology was obtained to process the parameter "duration of short-circuit" through an appropriate adjustment of empirical distributions to a lognormal model. the self-feed device for covered electrode welding allows the repeatable and reproducible execution of welding beads in the flat position, keeping the arc length based on physical and chemistry characteristics of the electrode during welding trials using 125a, 140a, and 160a.
Study of Fragmentation Process of Fused Fluxes Using Air Estudio del proceso de fragmentación de fundentes fundidos usando aire
Daniel Pérez Pérez,Carlos René Gómez Pérez,Francisco Arturo Ruiz Martínez,Jorge Víctor Miguel Oria
Revista Cubana de Ingeniería , 2011, DOI: 10.1234/rci.v2i2.47
Abstract: In the paper the fragmentation process with air of fused fluxes is studied by means of a particular treatment of the interaction process between the air and flux fluids starting from physical and mathematical considerations of the collision phenomenon which are the result of the application of Newton's mechanics-classical theory. In the paper is schematized the impact and change of trajectory process of the incandescent fused flux flow because of the air mechanical action provided by a blowpipe and the equations referred to the interaction between the fluids are set. As a result, the equations for estimating the exit angle and the average velocities of the pellets formed are determined whenever the interacting air and flux fluxes are known as well as the incidence angles. From the theory developed the essential parameters of the granulation process with air of fused fluxes, by considering the average diameter of the particles to be obtained for their industrial performance can be estimated. En el trabajo se estudia el proceso de fragmentación con aire de fundentes fundidos, a través de un tratamiento particular del proceso de interacción entre los fluidos de aire y de fundente, a partir de las consideraciones físicas y matemáticas del fenómeno de los choques que son resultado de la aplicación de la teoría mecano-clásica de Newton. Se esquematiza el proceso de impacto y cambio de trayectoria del chorro de fundente fundido incandescente por la acción mecánica del aire, suministrada por un soplador, y se plantean las ecuaciones referentes a la interacción entre los fluidos. Como resultado se determinan las ecuaciones para estimar el ángulo de salida y las velocidades promedio de los peles formados, si se conocen los flujos de fundente y de aire interactuantes, así como los ángulos de incidencia. A partir de la teoría desarrollada pueden estimarse los parámetros esenciales del proceso de granulación con aire de fundentes fundidos, considerando el diámetro medio de partículas a obtener para su ejecución industrial.
Influencia de la forma de los granos del fundente fundido CIS-F10 en la morfología y propiedades del metal depositado
Valdez, Marilene álvarez;Pérez, Daniel Pérez;Gómez Pérez, Carlos R.;Oria, Víctor Miguel;Quintana Puchol, Rafael;Perdomo González, Lorenzo;Crespo, Amado Cruz;
Soldagem & Inspe??o , 2010, DOI: 10.1590/S0104-92242010000200008
Abstract: in the present paper, the shape of fused grains flux cis-f10, granulated in air and in water, its effect on weld bead geometry and its properties were studied. grains morphology, properties, fluidity during piling, hygroscopic behavior and the amount of air between the grains during use were analyzed. the application of these procedures showed evidence that flux granulated in air (79.2 % of spherical particles) has fluidity relatively higher (34 %), smaller shape angle (28.8 %) and a lesser intergranular air per volume (28.2 %) than the flux granulated flux in water, despite the decrease in the slope of the humectation curve. the conjugation of these aspects improve penetration (8 %) and a reduction in the width of the heat affected zone (17 %) although neither metallographic nor mechanics (< 1%) differences are shown on the welds. the slag formed in both cases is of constant geometric configuration (4 mm thickness and 25 mm width) with 0.64 flux consumption rate.
Evolutionary Optimization of Electric Power Distribution Using the Dandelion Code
Jorge Sabattin,Carlos Contreras Bolton,Miguel Arias,Víctor Parada
Journal of Electrical and Computer Engineering , 2012, DOI: 10.1155/2012/738409
Abstract: Planning primary electric power distribution involves solving an optimization problem using nonlinear components, which makes it difficult to obtain the optimum solution when the problem has dimensions that are found in reality, in terms of both the installation cost and the power loss cost. To tackle this problem, heuristic methods have been used, but even when sacrificing quality, finding the optimum solution still represents a computational challenge. In this paper, we study this problem using genetic algorithms. With the help of a coding scheme based on the dandelion code, these genetic algorithms allow larger instances of the problem to be solved. With the stated approach, we have solved instances of up to 40,000 consumer nodes when considering 20 substations; the total cost deviates 3.1% with respect to a lower bound that considers only the construction costs of the network.
EFECTO DE LA ALTURA DEL MANGUITO EN UNIONES SOLDADAS EN CA?ERíAS DE COBRE
Carmona,Víctor; Vergara D,Jorge; Godoy R,Juan Miguel;
Ingeniare. Revista chilena de ingeniería , 2006, DOI: 10.4067/S0718-33052006000200008
Abstract: copper tubes were drilled with thermal flow drilling. conventional hss drills diameters were used to make pre drilling holes. different height bushings were made. two of the bushing heights were selected. the bushing circularity was measured. a ? 12,7 mm tube was welded perpendicularly on a ? 28,6 mm tube. a especial support device was designed and it was adapted to the universal test machine, to determine the tensile stress of the brazing joint. the micro hardness and metallographic test were made in the brazing zone. as a conclusion the lower height bushing is enough to reach the maximum resistance.
EFECTO DE LA ALTURA DEL MANGUITO EN UNIONES SOLDADAS EN CA ERíAS DE COBRE BUSHING HEIGHT EFFECT IN SOLDERED COPPER PIPE JOINTS
Víctor Carmona,Jorge Vergara D,Juan Miguel Godoy R
Ingeniare : Revista Chilena de Ingeniería , 2006,
Abstract: Se perforó un tubo de cobre de 28,6 mm de diámetro, por el proceso de taladrado por fluencia térmica (TFT). Se prepararon manguitos de diferentes alturas, haciendo un preperforado con brocas convencionales HSS de diferentes diámetros. Se seleccionaron manguitos de dos alturas diferentes. Se determinó la circularidad de la perforación. Se soldó un tubo cobre de 12,7 mm en forma perpendicular a un tubo de cobre de 28,6 mm y se determinó la resistencia a la tracción de la unión soldada, para lo cual se dise ó un dispositivo mecánico que fue adaptado en la máquina universal de ensayos. Se hicieron ensayos de microdureza y metalografía de la unión. Se concluyó que el manguito de menor altura es suficiente para que la unión alcance la máxima resistencia. Copper tubes were drilled with thermal flow drilling. Conventional HSS drills diameters were used to make pre drilling holes. Different height bushings were made. Two of the bushing heights were selected. The bushing circularity was measured. A 12,7 mm tube was welded perpendicularly on a 28,6 mm tube. A especial support device was designed and it was adapted to the Universal Test Machine, to determine the tensile stress of the brazing joint. The micro hardness and metallographic test were made in the brazing zone. As a conclusion the lower height bushing is enough to reach the maximum resistance.
El análisis narrativo en la educación física y el deporte.
Víctor Pérez Samaniego,Jorge Fuentes Miguel,José Devís Devis
Movimento , 2011,
Abstract: Este artículo complementa otro anterior publicado en esta misma revista (v. 17, n.1, 2011) en el que se reflexionaba sobre las cuestiones de qué es la investigación narrativa y qué puede ofrecer al estudio de la educación física y el deporte. Este trabajo se ocupa de la vertiente metodológica de la investigación narrativa, concretamente del análisis narrativo. En primer lugar se expone qué se entiende por análisis narrativo. En segundo lugar, se distingue entre dos grandes estrategias utilizadas para analizar narrativas, las que enfatizan la historia y las que enfatizan el análisis. La tipología se completa con una revisión de varios estudios que centran su foco de análisis en el Qué y/o el Cómo de los relatos. Finalizamos con una serie de consideraciones para animar y, a la vez, invitar a los investigadores a ser prudentes a la hora de analizar narrativas.
Optimización de donantes expandidos con el trasplante birrenal: estudio caso-control
Frutos,Miguel á.; Mansilla,Juan J.; Cabello,Mercedes; Soler,Jorge; Ruiz,Pilar; Lebron,Miguel; Baena,Víctor; Hernández,Domingo;
Nefrología (Madrid) , 2012,
Abstract: introduction: in order to take full advantage of ecd kidneys, which may not provide sufficient renal mass if used individually, it has been suggested that such organs be used in dual or bilateral kidney transplantation (dtx). patients and method: we analysed the experience in a single hospital between may 2007 and march 2011 in a case-control study. criteria for determining whether to perform single or dual tx were defined in a protocol in which the biopsy score was important, but not the only factor. donor's age, medical history, kidney size and creatinine clearance were also considered. during this time period, 80 kidneys from donors over age 65 were transplanted. single transplants (stx) accounted for 40 of the organs, and another 40 were used in dtx. results: mean donor age for stx was 68.7±3.0 years; for dtx, it was 74.2±4.3 years (p<.001), with more female donors for dtx (75%) than for stx (40%) (p<.001). there were no differences between groups with regard to glomerular filtration rate or proteinuria. kidneys assigned to dtx received higher biopsy scores than those assigned to stx (2.95±1.01 vs 1.8±1.04; p<.001). dtx recipients were older than stx recipients. there were no differences between the groups regarding cold ischaemia time, delayed graft function, haemorrhagic complications or re-surgeries. however, dtx recipients achieved better creatinine clearance at 1, 3, 6 and 12 months, although the difference was only statistically significant at 6 months (53.4±19.5ml/min vs 44.5±15.6ml/min; p<.05). renal artery thrombosis appeared in 2 stx patients and in both kidneys of 1 dtx patient. another 2 patients in the dtx group each lost 1 kidney due to thrombosis and ureteral necrosis respectively, but were able to remain dialysis-free. graft survival at 3 years was 90% for both groups. during the study period 3 patients died (2 in the stx group and 1 in the dtx group). conclusions: our preliminary experience indicates that dtx provides good results in terms of su
Horizontal gene transfer and diverse functional constrains within a common replication-partitioning system in Alphaproteobacteria: the repABC operon
Santiago Castillo-Ramírez, Jorge F Vázquez-Castellanos, Víctor González, Miguel A Cevallos
BMC Genomics , 2009, DOI: 10.1186/1471-2164-10-536
Abstract: We did not find a single evolutionary history within the repABC operon. Each protein had a particular phylogeny, horizontal gene transfer events of the individual genes within the operon were detected, and different functional constraints were found within and between the Rep proteins. When different repABC operons coexisted in the same genome, they were well differentiated from one another. Finally, we found different levels of adaptation to the host genome within and between repABC operons coexisting in the same species.Horizontal gene transfer with conservation of the repABC operon structure provides a highly dynamic operon in which each member of this operon has its own evolutionary dynamics. In addition, it seems that different incompatibility groups present in the same species have different degrees of adaptation to their host genomes, in proportion to the amount of time the incompatibility group has coexisted with the host genome.The repABC plasmids are a typical genome component of many Alphaproteobacteria species. In fact, more than 20 Alphaproteobacteria species have at least one repABC plasmid (see refs [1,2] for recent reviews), these repABC plasmids may be the commonest plasmids in Alphaproteobacteria species. In some species these repABC plasmids constitute a significant amount of the bacterial genome; such is the case of Rhizobium leguminosarum 3841, in which repABC plasmids account for 35% of the genome [3]. This plasmid family includes several incompatibility groups, meaning that more than one type of repABC plasmid can reside in the same bacterial species [1,2]. For instance, Rhizobium etli CFN42 has 6 plasmids, all of them repABC plasmids [4]. In contrast to other low copy-number plasmids, in which the elements involved in plasmid replication and segregation are located on different loci (each one under its own regulatory circuit), the repABC plasmids contain all the elements required for replication and partition within the repABC operon. In gene
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