A Bayesian Approach for Estimating the Thinning Corrosion Rate of Steel Heat Exchanger in Hydrodesulfurization Plants

Fuel consumption has been increasing in recent years, especially that of diesel and jet fuel. For this reason, the necessity to build new plants to reduce their sulfur content has arisen. Sometimes, just revamping existing plants is feasible, but determining which pieces of equipment are in the appropriate condition to be reused is also necessary. In order to select the equipment, it is essential to have information about the wall thickness of vessels. Sometimes, the information is limited; consequently, the application of advanced statistical techniques is needed. ,e Bayesian Data Analysis (BDA) used in this study has the goal of determining a more accurate, unobserved thinning rate distribution for existing heat exchangers, taking into consideration all the information available about the thinning rate of the heat exchangers that cool down the effluent of the hydrotreating reactors in Mexican oil refineries. ,e information obtained from BDA was compared with existing shell wall thickness obtaining favorable results

Necesidades de aprendizaje en posgraduados de la especialidad de Psiquiatría

Fundamento: la determinación de las necesidades de aprendizaje es indispensable para poder garantizar la calidad de los programas de superación profesional en cualquiera de sus variantes, incluyendo el posgrado.Objetivo: identificar las necesidades de aprendizaje en los residentes de Psiquiatría egresados de los cursos 2012-2013 al 2014-2015.Métodos: se realizó una investigación descriptiva con enfoque cualitativo, en el campo de las ciencias médicas, específicamente en el área de posgrado del Hospital Psiquiátrico Provincial Docente “Dr.C. Luis San Juan Pérez” de Villa Clara. Se utilizaron métodos del nivel teórico: analítico-sintético e inductivo-deductivo, y empírico: encuesta en forma de entrevista a los posgraduados, profesores y administrativos para identificar las necesidades de aprendizaje.Resultados: se identificaron como las principales necesidades: pocas habilidades en la práctica psicoterapéutica, insuficiencia de conocimientos básicos en Anatomía y Fisiología del sistema nervioso para la comprensión de determinados procesos metabólicos cerebrales que sustentan en su mayoría las bases psicofarmacológicas, ausencia de conocimientos jurídicos, poco adiestramiento para asumir otras funciones además de la asistencial, como son la docente, investigativa y gerencial, falta de habilidades en la indicación e interpretación de los test psicométricos para definir diagnósticos en la especialidad y deficiencias en la elaboración de los diagnósticos de salud mental.Conclusiones: se identificaron necesidades de aprendizaje en los posgraduados de los cursos evaluados en cuanto a conocimientos básicos y específicos de la especialidad que afectan la comprensión de determinados procesos psíquicos, e insuficiencias metodológicas para asumir determinadas funciones docentes, investigativas y gerenciales

Mechanical properties, microstructure and crystallographic texture of magnesium AZ91-D alloy welded by Friction Stir Welding (FSW)

The objective of the study was to characterize the properties of a magnesium alloy welded by friction stir welding (FSW). The results led to a better understanding of the relationship between this process and the microstructure and anisotropic properties of alloy materials. Welding principally leads to a large reduction in grain size in welded zones due to the phenomenon of dynamic recrystallization. The most remarkable observation was that crystallographic textures appeared from a base metal without texture in two zones: the thermo-mechanically affected and stir welded zones. The latter zone has the peculiarity of possessing a marked texture with two components on the basal plane and the pyramidal plane. These characteristics disappeared in the TMAZ, which had only one component following the basal plane. These modifications have been explained by the nature of the plastic deformation in these zones, which occurs at a moderate temperature in the TMAZ and high temperature in the SWZ

Study of Mechanical Properties of AZ91 Magnesium Alloy Welded by Laser Process Taking into Account the Anisotropy Microhardness and Residual Stresses by X-Ray Diffraction

The objective was to study the mechanical properties of a magnesium alloy welded by a CO2 laser. Residual stresses were measured by X-ray diffraction. They were calculated by the classic sin2Y method in the isotropic zones by using the orientation distribution function (ODF) in the textured zones. The results demonstrated that laser welding results in the formation of a number of different zones with different microstructural and mechanical properties. Welding principally leads to a reduction in grain size and a new distribution of phases. The most remarkable observation was that of a superficial layer on the surface of the welded zone. This layer has the peculiarity of a marked crystallographic texture, a reduction in the level of aluminium as well as an elevated microhardness. These characteristics disappear after a depth of 200μm under the welded zone. These modifications can be explained by the nature of the solidification which occurs under nonequilibrium conditions resulting in an equiaxial columnar transition. This transition is also evident within the profile of residual tensile stresses which are at their maximum at the interface between the superficial layer and the rest of the welded zone. These results are explained by the anisotropic properties of the textured layer in relation to the plasticity

Study of the development of the cube texture in Fe-50%Ni during recrystallization and normal grain growth

The development of the cube texture has been investigated in a Fe-50%Ni alloy undergoing recrystallization and normal grain growth by means of orientation imaging microscopy (OIMTM) and bulk texture measurements (X-ray diffraction). It is shown that both the oriented nucleation and the oriented growth mechanisms are responsible for the strengthening of the cube texture in the early stages of recrystallization in this alloy. The increase in the cube texture in the intermediate stages of recrystallization is mainly related to the high differentials in stored energy associated with cube grains. These experimental results are corroborated by way of a Monte-Carlo simulation of recrystallization based on data derived by OIM of the investigated alloy at its earliest recrystallization stages. The primary mechanism responsible for the development of the cube texture during grain growth relies on the preferential migration of the high-angle grain boundaries linked to cube grains which results from the advantage in number and size shown by cube grains when recrystallization is complete