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Search Results: 1 - 10 of 358780 matches for " Orlando; de Rincón "
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Evaluation of duplex coating?s system in tropical marine environments
Romero,Nathalie; de Rincón,Oladis; Sánchez,Miguel; Rincón,álvaro; Millano,Valentina; Linares,Douglas; Salas,Orlando; Serrano,Mirla;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: in this work nine different coating systems, from national suppliers, were selected to perform the evaluation in two severe tropical marine environments. new galvanized profiles as well as pre-exposed to the same environmental conditions were used as the test probes. two different field stations were selected: la voz and the cross of maracaibo lake. additionally, accelerated test were carried out in a station located at centro de estudios de corrosión (cec) by using the standard iso 11474, and in the laboratory (prohesion chamber). it is important to emphasize that after more than 36 month-exposure the behavior of the different coating systems on pre-exposed galvanized was clear, permitting to select the coating system with the best performance. nevertheless in the case of new galvanized probes, after the evaluation period, most of the duplex systems had a very good performance.
Efecto de los iones ferrosos, el pH y el H2S a nivel de interfase en el mecanismo de corrosión del hierro por bacterias sulfato-reductoras Influence of ferrous ions, pH and H2S at the interface on the corrosion mechanism of iron by Sulfate-Reducing Bacteria
Lisseth Ocando,Matilde Fernández de Romero,Orlando Pérez,Oladis T de Rincón
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: La Corrosión Inducida Microbiológicamente (MIC) por Bacterias Sulfato-Reductoras (BSR) es un fenómeno que acarrea graves da os para muchas industrias y sistemas. Numerosas teorías se han formulado para explicar los mecanismos que gobiernan MIC y, recientemente, ha sido propuesto un mecanismo de corrosión del hierro por estas bacterias. En este mecanismo se ha establecido que los sulfuros de hierro precipitados son los que propician el proceso corrosivo del acero, junto con el H2S generado por las BSR, y supone que, por la actividad metabólica de las mismas, en la interfase metal/solución ocurre un descenso del pH que acelera el proceso corrosivo de forma localizada. Por tanto, el objetivo principal de esta investigación consistió en evaluar el pH a nivel de interfase metal/solución, tanto en medios con iones ferrosos (al igual que en el mecanismo) como en ausencia de ellos, con el propósito de verificar la ocurrencia de esta acidificación y determinar la influencia de estos iones en el proceso corrosivo. También, evaluar la concentración deH2S a nivel de interfase y determinar su relación con el pH. Para medir estos dos parámetros durante 24 horas en ambos medios, se utilizó microelectrodos de pH y H2S. Por otro lado, se determinó la morfología de biopelícula y de ataque en los dos medios de cultivo mediante microscopía electrónica de barrido (MEB). Los resultados arrojaron que el pH disminuye a nivel de interfase metal/solución dependiendo de la presencia de iones ferrosos. Adicionalmente, con esta investigación se confirmó la influencia adversa de los iones Fe++ y la agresividad de los sulfuros de hierro en el proceso corrosivo. Microbiologically Influenced Corrosion (MIC) by Sulfate-Reducing Bacteria (SRB) has been the subject of extensive studies for the past five decades and several theories have been proposed to explain the mechanisms governing MIC. Recently, a corrosion mechanism for the action of SRB on iron was proposed, which seeks to explain the initiation of this kind of corrosion in order to improve prevention and mitigation techniques. This mechanism was supported on the fact that there should be a local pH decrease at the metal/solution interface. So, the principal aim of this work was to prove this theory by evaluating an iron interface exposed to a culture medium rich in nutrients and SRB. The H2S concentration produced was also evaluated to establish its relation with the pH at the interface. To measure these parameters during 24 hours, pH and H2S microelectrodes with tip diameters of 10 μm were used. A SRB pure culture of Desulfovibri
Operational factors affecting the hot dip galvanizing steel
Sánchez,Miguel; Contreras,Ramón; Pérez,Orlando; de Rincón,Oladis; Campos,William;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: an evaluation by hot dip galvanizing on steel after a 1; 2 and 3-minutes immersion was studied. these samples were carried out for evaluating microhardness and thickness measurements. electrochemical techniques were used to determined the corrosion rate of steel in acid pickling 5; 10 and 16% hcl; rinsed with water of ph 2.50; 3.50 and 4.50 and hot dip galvanized steel in 3.5% nacl. certain operational parameters were analyzed, such as the aging bath (hcl), and elimination of the rinsing stage, to observe their influence in the hot dip galvanizing coating. it was found that an increase of coating thickness of hot dip galvanizing steel decreased the corrosion rate and the microhardness. surfaces of alloy layer of the coating were examined by scanning electron microscope (sem). sem measurements was determined that when obvious the rinsing, the chlorine can be catched between two layers (interface), and soon migrates of the outermost alloy layer of the coating (delta) towards the innermost one (gamma).
Factores operacionales que afectan el comportamiento del acero galvanizado por inmersión en caliente Operational factors affecting the hot dip galvanizing steel
Miguel Sánchez,Ramón Contreras,Orlando Pérez,Oladis de Rincón
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: En este trabajo se presentan los resultados de la evaluación de probetas de acero galvanizado por inmersión en caliente con tiempo de ba o de 1, 2 y 3 minutos. Se realizaron ensayos de espesor de recubrimiento y mediante técnicas electroquímicas se midió la velocidad de corrosión del acero en soluciones de ba os ácidos a 5; 10 y 16% de HCl y agua de enjuage pH 2,50; 3,50 y 4,50; y del acero galvanizado en una solución de NaCl 3,5%. Se analizaron ciertos parámetros operacionales, tales como el envejecimiento del ba o ácido (HCl), y eliminación de la etapa de enjuague, para observar su influencia en el recubrimiento de cinc. Se encontró que a medida que aumenta el espesor del recubrimiento disminuye la velocidad de corrosión. Mediante el uso del microscopio electrónico de barrido se determinó que cuando se obvia el enjuague, el cloro puede quedar atrapado entre dos capas (interfase), y luego migra de la capa superior (Delta) hacia la inferior (Gamma). An evaluation by hot dip galvanizing on steel after a 1; 2 and 3-minutes immersion was studied. These samples were carried out for evaluating microhardness and thickness measurements. Electrochemical techniques were used to determined the corrosion rate of steel in acid pickling 5; 10 and 16% HCl; rinsed with water of pH 2.50; 3.50 and 4.50 and hot dip galvanized steel in 3.5% NaCl. Certain operational parameters were analyzed, such as the aging bath (HCl), and elimination of the rinsing stage, to observe their influence in the hot dip galvanizing coating. It was found that an increase of coating thickness of hot dip galvanizing steel decreased the corrosion rate and the microhardness. Surfaces of alloy layer of the coating were examined by scanning electron microscope (SEM). SEM measurements was determined that when obvious the rinsing, the chlorine can be catched between two layers (interface), and soon migrates of the outermost alloy layer of the coating (Delta) towards the innermost one (Gamma).
Six-Year Evaluation of Thermal-Sprayed Coating of Zn/Al in Tropical Marine Environments
Orlando Salas,Oladis Troconis de Rincón,Daniela Rojas,Adriana Tosaya,Nathalie Romero,Miguel Sánchez,William Campos
International Journal of Corrosion , 2012, DOI: 10.1155/2012/318279
Abstract: The main objective of this research was to evaluate the performance of thermal-sprayed coating of Zn/Al (double layer) after six years of exposure, with and without the use of sealant (wash primer) in tropical marine environments of very high aggressiveness: La Voz Station (located at the Peninsula de Paraguaná/Falcón State) and Lake Maracaibo Crossing Station (located at Zulia State), in Venezuela. To that effect, carbon steel coupons (100?mm × 150?mm × 2?mm) were sprayed by flame process. The coupons were characterized by means of initial weight, thickness, metallographic, adherence, and roughness, being evaluated monthly by visual inspection during six years. After removal, the coupons were evaluated by microscopic analysis to determine the morphology of attack, microstructure, penetration of contaminants, composition, and morphology of corrosion products. The results showed that after six years, the double-layer system represents an excellent choice for corrosion protection of steel by combining the galvanic protection of zinc with the erosion resistance of aluminum. However, due to the erosion-corrosion effect, a sealant such as wash primer can be used in order to extend its service life. 1. Introduction Worldwide, many organizations have made numerous efforts in terms of studies and research looking for new coating systems to improve the durability of structures exposed to marine and coastal marine environments, providing protection to the steel during its service life and producing a minimal impact on the environment. In marine and coastal marine environments, where a number of factors are present such as high-chloride concentrations, strong winds, changing conditions of relative humidity and temperature (especially in tropical climates like Venezuela), organic coatings do not perform properly. In this regard, thermal-sprayed coatings appear as an alternative to protect steel structures in those environments. In the United States, Europe, and Japan [1, 2], these coatings are gaining importance for their promising low environmental impact, corrosion resistance, cost benefits, durability, and other advantages over other conventional paint systems. In 1974, the American Welding Society [3] performed a study that was considered a pioneer in thermal sprayed coating where it reported that these coatings with Zn and Al, with and without sealer, exposed in marine and industrial environments, provided protection against corrosion for 19 years. Moreover, in 1987, the Laque Center for Corrosion Technology, INC. [4] reported that the degree of protection of
Influence of ferrous ions, pH and H2S at the interface on the corrosion mechanism of iron by Sulfate-Reducing Bacteria
Ocando,Lisseth; Fernández de Romero,Matilde; Pérez,Orlando; de Rincón,Oladis T; Duque,Zoilabet; León,Ennery; Atencio,Laura; Ortiz,Reynaldo;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: microbiologically influenced corrosion (mic) by sulfate-reducing bacteria (srb) has been the subject of extensive studies for the past five decades and several theories have been proposed to explain the mechanisms governing mic. recently, a corrosion mechanism for the action of srb on iron was proposed, which seeks to explain the initiation of this kind of corrosion in order to improve prevention and mitigation techniques. this mechanism was supported on the fact that there should be a local ph decrease at the metal/solution interface. so, the principal aim of this work was to prove this theory by evaluating an iron interface exposed to a culture medium rich in nutrients and srb. the h2s concentration produced was also evaluated to establish its relation with the ph at the interface. to measure these parameters during 24 hours, ph and h2s microelectrodes with tip diameters of 10 μm were used. a srb pure culture of desulfovibrio desulfuricans subs. desulfuricans was used, grown as batch culture in modified atcc 1249 medium with and without ferrous ions, in order to determine their influence on the ph and h2s behavior. attack morphology and biofilm structure in both mediums were also determined by scanning electron microscopy (sem). the results showed that ph into the biofilm decreased depending on the ferrous ions presence. also, it was confirmed the influence of ferrous ions and ferrous sulfides aggressiveness in the corrosion process established in the mechanism.
Effect of pore sealer in the behavior of thermal sprayed aluminum and zinc coatings in marine and coastal marine atmospheres
Salas,Orlando; Rincón,álvaro; Rincón,Oladis T.; Sánchez,Miguel; Maldonado,Luis;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2006,
Abstract: the objective of this research is to study the effect that have pore sealers in the behavior of thermal sprayed cinc y aluminum, and zn/al coatings in marine and coastal marine atmospheres, during one year of exposition. to that effect, carbon steel sheets (10cm x 15cm × 3 mm) were sprayed by using two different processes (electric arch and flame spray), with and without the application of two additional layers of sealer. three sealers were evaluated: two wash primers of different suppliers, and a phenolic sealer. the sheets were exposed in two atmospheric test sites, la voz (coastal marine atmosphere), and the towers of the crossing of the lake of maracaibo (marine atmosphere). the sheets were characterized by means of initial weight, thickness, metallographic, adhesion, roughness, being evaluated monthly by visual inspection and photographic. the results showed that in these aggressive atmospheres, where the wind effect is important, the thermal sprayed zn/al coating, offers an excellent behavior even without sealer, producing galvanic protection to the substrate. in the case of thermal sprayed of cinc and aluminum coatings, a phenolic based pore sealer should be used, for covering completely the irregularities owned by this type of coating.
Patrones de dispersión de semillas por aves en perchas en un gradiente altitudinal con alteración antrópica
Vargas Rincón Carlos Alberto,Vargas Ríos Orlando
Acta Biológica Colombiana , 2006,
Abstract: En tres sitios ubicados en un gradiente altitudinal de bosque altoandino sometido a disturbio antrópico, se estudiaron patrones de arribo de semillas dispersadas por aves a perchas en áreas abiertas. Se logró determinar que el arribo de semillas a estas estructuras está relacionado con el grado de fragmentación del bosque, así como tambien de la diversidad de los parches de bosque aleda os. La especie de ave que más frecuentó las perchas fue Turdus fuscater, debido a que es una especie que vuela en campo abierto. Además, que al ser una especie altamente omnivora es capaz de promover la llegada a las perchas de semillas de diferentes especies.
KNOWLEDGE CONSERVATION AND TRANSFER: A STRATEGIC VISION FOR COSTS REDUCTION IN ORGANIZATIONS LA CONSERVACIóN Y TRANSFERENCIA DEL CONOCIMIENTO: UNA VISIóN ESTRATéGICA PARA LA DISMINUCIóN DE COSTOS EN LAS ORGANIZACIONES
Haydeé Rincón de Parra
Revista Universo Contábil , 2007,
Abstract: The companies have always acted in order to maintain the best levels of productivity and the biggest competitive advantages with respect to market. Nowadays, when knowledge has been considered the fundamental element or resource in economy, it becomes necessary to conserve it, so that one could transfer it to the successors in case those who possess it now were no longer in the company. In this article, a product of a review and analysis of specialized literature, it is sought to present some aspects which shed light on why and how knowledge conservation and transfer (knowledge continuity management) are seen as strategy that enables costs to be reduced in organizations. To achieve this proposal, tentative answers will be given to the following questions: a) How can organizations conserve and transmit operating knowledge to maintain knowledge continuity?, b) Which are organizations’ costs when operating knowledge is created?, c) Why do conservation and transmission of operating knowledge become competitive advantage for organizations?, d) Why can knowledge conservation and transmission be seen as a strategy to reduce costs? Keywords: Knowledge conservation and transfer. Costs of operating knowledge creation. Costs reduction Las empresas siempre han actuado en función de mantener los mejores niveles de productividad y las mayores ventajas competitivas con relación al mercado. Hoy, cuando el conocimiento está siendo considerado el elemento o recurso fundamental en la economía, se hace necesario conservarlo, a los efectos de que pueda ser transferido a los sucesores, cuando quien lo posee ya no estará en la empresa. A través de este escrito, se pretende, producto de la revisión y análisis de la literatura especializada, presentar algunos aspectos que dan cuenta del por qué y cómo la conservación y transferencia del conocimiento (gerencia de la continuidad del conocimiento), es vista como una estrategia que permite reducir los costos en las organizaciones. Para ello, se intentará dar respuestas a las siguientes interrogantes: a) Cómo las organizaciones pueden conservar y transmitir el conocimiento operativo, a los efectos de mantener la continuidad del conocimiento?, b) Cuáles son los costos en que incurren las organizaciones al crear conocimiento operativo?, c) Por qué la conservación y transmisión del conocimiento operativo se convierte en una ventaja competitiva para las organizaciones?, d) Por qué la conservación y transmisión del conocimiento puede ser vista como una estrategia para disminuir costos? Palabras-claves: Conservación y transferencia de
La calificación jurídica de las transmisiones de software en Internet
Arias de Rincón,María Inés;
Frónesis , 2007,
Abstract: this research project evaluates the legal business concerns that arise from software exchange on the internet. to achieve this goal, the study differentiates between electronic data as incorporeal supports of computer programs when they travel on the web and the computer program these contain as works protected by copyright. based on this consideration, the types of contracts that arise are described in relation to the duality of their object (incorporeal good and intangible good). conclusions affirm that in software transmission, two connected contracts appear: the sale of the incorporeal support of the intellectual creation (electronic data) and the license or rights of use from the author.
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