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Search Results: 1 - 10 of 4749 matches for " Gerardo Zavala Olivares "
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Corrosion of Steel Pipelines Transporting Hydrocarbon Condensed Products, Obtained from a High Pressure Separator System: A Failure Analysis Study  [PDF]
Gerardo Zavala Olivares, Mónica Jazmín Hernández Gayosso
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.68078
Abstract: In this paper, the corrosion of steel pipelines transporting hydrocarbon condensed products was studied. Different activities of sampling and analysis were carried out to diagnose the failure causes and to establish a control system for the corrosion problem. The combination of three types of corrosion, including erosion corrosion, galvanic corrosion and microbiologically induced corrosion, was synthetically considered. A serial of experiments were designed to research those types of corrosion. This type of failure was observed in characteristics sites of the pipeline, mainly in direction changes and welding joints. Additionally, localized corrosion was observed in the inner steel wall and distributed along the pipeline, although a tendency was not detected.
Steel Pitting Corrosion Analysis, Using a High Vaccum Epoxy Penetration Technique  [PDF]
Gerardo Zavala Olivares, Mónica J. Hernández Gayosso, Rafael García Esquivel
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.41002

An epoxy penetration technique was used to reproduce and analyze the pitting corrosion process occurred at a steel coupon surface. The samples were exposed to the resin under high vacuum conditions, in order to fulfill the pits caused by the corrosion process. With this technique, a 3D image of the corrosion damages was obtained. Once the image of the damaged surface was obtained, a Scanning Electron Microscope (SEM) was used to analyze the morphology of the pits exhibited by the steel sample. The results were satisfactory, as different parameters such as the diameter, shape and depth of the pits originated, along with the corrosion preferential path, could be established. According to the results, the use of the epoxy penetration technique may be considered as alternating pitting corrosion analysis technique.

Corrosion Behavior of API 5L X52 Steel under High Concentrations of H2S/CO2 Gases  [PDF]
Mónica Jazmín Hernández Gayosso, Gerardo Zavala Olivares, Saúl Bautista Fragoso, Gabriel Ernesto Blanco del Valle, Daniel Mauricio Godínez Oidor, Víctor ángel Rodríguez Gómez
Materials Sciences and Applications (MSA) , 2016, DOI: 10.4236/msa.2016.710051
Abstract: In the present work, the susceptibility of API 5L X52 steel to corrosion processes was evaluated in the presence of high contents of hydrogen sulfide and carbon dioxide. Gravimetric tests and surface analyses were carried out to establish both the corrosion rate and damage type exhibited by the metal. The obtained results indicate that the hydrogen sulfide is the most active gas in the corrosion processes that took place, quite above carbon dioxide. The main observed corrosion products were iron sulfides and the typical damage associated with hydrogen sulfide presence was Sulfide Stress Cracking (SSC). The surface damage evidences the presence of cracks with considerable magnitude and metal loss as consequences of the corrosion processes. Likewise, the presence of oxygen in the system modifies the displayed corrosion type, where corrosion products such as iron oxides and reduction in the number and extent of cracks are observed. On the other hand, the addition of a film-forming corrosion inhibitor based on modified imidazolines eliminates completely the development of cracks, although under certain test conditions, it can favor localized pitting corrosion.
Evaluation of Stress Corrosion Cracking Damage to an API 5L X52 Pipeline Transporting Ammonia: A Case Study  [PDF]
José Luis Mora-Mendoza, Mónica Jazmín Hernández-Gayosso, Daniel Antonio Morales-Serrat, Octaviano Roque-Oms, Digna Alejandra Del Angel, Gerardo Zavala-Olivares
Materials Sciences and Applications (MSA) , 2016, DOI: 10.4236/msa.2016.710050
Abstract: The high number of leak events that took place in recent years at a 25.4 cm (10”)Ø pipeline transporting anhydrous liquid ammonia, located in the Southeast of Mexico, was the main reason to carry out a number of field studies and laboratory tests that helped establish not only the failure causes but also mitigation and control solutions. The performed activities included direct evaluation at failure sites, total repair programs, metallographic studies and pipeline flexibility analyses. The obtained results were useful to conclude that the failures obeyed a cracking mechanism by Stress Corrosion Cracking (SCC) which was caused by the combined effect of different factors: high stress resistance, high hardness of the base metal with a microstructure prone to brittleness and residual strains originated during the pipeline construction. From the operative, logistic and financial standpoints, it is not feasible to release the stress of approximately 22 km of pipeline. Therefore, the only viable solution is to install a new pipeline with suitable fabrication, construction and installation specifications aimed at preventing the SCC phenomenon.
Electrodeposition of Nickel Particles and their Characterization
Martínez, Gerardo T.;Zavala, Genaro;Videa, Marcelo;
Journal of the Mexican Chemical Society , 2009,
Abstract: electrodeposition of nickel particles on ito substrates is achieved by current pulse reduction. a comparison between potential pulse and current pulse experiments presents differences in particle size and particle size distribution. the latter shows smaller particle size dispersion than what is found with potential pulses. characterization of the particles carried out by atomic force microscopy shows particles with average sizes between 100 to 300 nm. magnetic characterization by magnetic force microscopy and squid shows that particles of ~300 nm were ferromagnetic with a coercive field of 200 oe and a saturation magnetization of 40 × 10-6 emu at 300 k.
Electrodeposition of Nickel Particles and their Characterization
Gerardo T. Martínez,Genaro Zavala,Marcelo Videa
Revista de la Sociedad Química de México , 2009,
Abstract: Se realizó la electrodeposición de partículas de níquel sobre substratos de ITO mediante la aplicación de pulsos de corriente. La comparación entre el método de pulsos de potencial y pulsos de corriente muestra diferencias en el tama o de partícula y su distribución. El método de pulsos de corriente conduce a una menor dispersión en el tama o de partícula que el observado con pulsos de potencial. La caracterización de las partículas se llevó a cabo por Microscopía de Fuerza Atómica mostrando partículas con un tama os promedio entre 100 y 300 nm. Mediante Microscopía de Fuerza Magnética y SQUID se determinó que partículas de ~300 nm son ferromagnéticas, con un campo coercitivo de 200 Oe y una magnetización de saturación de 40 × 10-6 emu a 300 K.
Complexity, Selectivity and Asymmetry in the Conformation of the Power Phenomenon. Analysis of Chilean Society
Juan Pablo Cárdenas,Gerardo Vidal,Gastón Olivares
Computer Science , 2014,
Abstract: In this work we analyzed the relationships between powerful politicians and businessmen of Chile in order to study the phenomenon of social power. We developed our study according to Complex Network Theory but also using traditional sociological theories of Power and Elites. Our analyses suggest that the studied network displays common properties of Complex Networks, such as scaling in connectivity distribution, properties of small-world networks, and modular structure, among others. We also observed that social power (a proposed metric is presented in this work) is also distributed inhomogeneously. However, the most interesting observation is that this inhomogeneous power and connectivity distribution, among other observed properties, may be the result of a dynamic and unregulated process of network growth in which powerful people tend to link to similar others. The compatibility between people, increasingly selective as the network grows, could generate the presence of extremely powerful people, but also a constant inequality of power where the difference between the most powerful is the same as among the least powerful. Our results are also in accordance with sociological theories.
Indoor Propagation Modeling for Radiating Cable Systems in the Frequency Range of 900-2500 MHz
Jorge Alberto Sesena-Osorio;Alejandro Aragon-Zavala;Ignacio E. Zaldivar-Huerta;Gerardo Castanon
PIER B , 2013, DOI: 10.2528/PIERB12102314
Abstract: The aim of this paper is to propose and evaluate a semi-empirical propagation modeling for radiating cable used in indoor environments. This propagation modeling takes into consideration propagation mechanisms such as reflections, penetration loss and cable termination that result from a particular environment, as well as specific cable paths that actual propagation models for radiating cable systems have not considered. The proposed modeling is carried out using three different propagation models and has been experimentally validated by sets of measurements performed in a university building in the frequency range from 900 MHz to 2.5 GHz. A careful selection of the data sets validates the robustness of the proposed model. The results show a mean of the error less than 1 dB while the standard deviation is between 2.2 dB and 4.6 dB in all cases. To the best of our knowledge, this is the first time such a robust modeling for radiating cable operating between 900 MHz to 2.5 GHz has been presented.
Zavala,Patricio; Zavala,Carlos;
Revista Facultad de Ingeniería - Universidad de Tarapacá , 2002, DOI: 10.4067/S0718-13372002001000005
Abstract: this paper describes the methodology used, to generate building height cartography, through the analysis of high resolution satellite images of the city of arica, in northren chile. calculations were made using shadow lengths, derived from different constructions, and from the solar azimuth of an irs image 1c, that was processed by cubic convolution at 5 meters. this research project is based on the development of the doctoral thesis of one of the authors (1), related to the analysis of seismic vulnerability using geografical information system (g.i.s) technology and remote sensing techniques. the results of this project will yield cartography, that we hope will be useful for urban territorial management.
Patricio Zavala,Carlos Zavala
Revista Facultad de Ingeniería - Universidad de Tarapacá , 2002,
Abstract: Se presenta la metodología aplicada en la ciudad de Arica, Norte de Chile, para generar cartografía de altura de construcciones, mediante el análisis digital de una imagen satelital de alta resolución. Para ello, nos basamos en el cálculo de la longitud de las sombras que se derivan de distintas edificaciones, y del azimut solar de una imagen IRS 1C, que fue remuestreada mediante convolución cúbica a 5 metros. Este trabajo está basado fundamentalmente en los logros alcanzados en el desarrollo de la tesis doctoral de uno de los autores (1), y que se refirió al análisis de vulnerabilidad sísmica mediante técnicas de Sistema de Información Geográfico (S.I.G.) y Teledetección. Los resultados logrados creemos permitirán obtener cartografía resultante, que esperamos sea útil para la gestión territorial a nivel intraurbano. This paper describes the methodology used, to generate building height cartography, through the analysis of high resolution satellite images of the city of Arica, in northren Chile. Calculations were made using shadow lengths, derived from different constructions, and from the solar azimuth of an IRS image 1C, that was processed by cubic convolution at 5 meters. This research project is based on the development of the doctoral thesis of one of the authors (1), related to the analysis of seismic vulnerability using Geografical Information System (G.I.S) technology and remote sensing techniques. The results of this project will yield cartography, that we hope will be useful for urban territorial management.
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