Numerical simulation of the heat penetration in two-plate arc welding

A mathematical model and numerical simulation of the three-dimensional and transient metal arc-welding process is presented. The heat source is considered as spatially distributed following a centered Gaussian bell, while the substract material (Al 6063) is assumed homogeneous and isotropic with temperature-dependent thermal properties. Radiation and convection are also calculated through an empirical temperature dependent correlation. Phase-change phenomenon is included as a discontinuity in the material specific heat. Calculations were performed by using a finite volume code (CFX4.2TM). Computed heat penetration and weld metal area are found to be in good agreement with experimental data

Numerical simulation of the heat penetration in two-plate arc welding

A mathematical model and numerical simulation of the three-dimensional and transient metal arc-welding process is presented. The heat source is considered as spatially distributed following a centered Gaussian bell, while the substract material (Al 6063) is assumed homogeneous and isotropic with temperature-dependent thermal properties. Radiation and convection are also calculated through an empirical temperature dependent correlation. Phase-change phenomenon is included as a discontinuity in the material specific heat. Calculations were performed by using a finite volume code (CFX4.2TM). Computed heat penetration and weld metal area are found to be in good agreement with experimental data

Experience management by the international office of higher education institutions

El objetivo del presente estudio es analizar la gestión de la experiencia de las unidades principales de internacionalización en las instituciones de educación superior de Barranquilla (Colombia). Se utiliza un enfoque epistemológico deductivo, paradigma cuantitativo de tipo descriptivo y un diseño no experimental de campo. Como técnica se usó la encuesta y se utilizó el cuestionario de escala tipo Likert aplicado a 13 directores pertenecientes a la unidad principal de internacionalización de las instituciones de educación superior que estén activas en el sistema nacional de información de la educación superior. Los datos recolectados fueron procesados a través de la técnica estadística de regresión múltiple. Como resultado se identifica una función matemática y se deduce que el proceso de la experiencia representa la contribución más alta con un 91.5%. Se concluye que la gestión de la experiencia es una herramienta cuando se implementan estrategias, se establecen procesos para la experiencia y se diseña el servicio.The main objective of this research study is to examine the management of customer experience by international offices of higher education institutions located in Barranquilla (Colombia). This study has a deductive epistemological approach, a descriptive quantitative paradigm, and a non-experimental field design. A survey with a Likert scale questionnaire is applied to 13 directors of international offices. Collected data is processed by multiple regression analyses. The results identify a mathematical function and deduce that the customer experience process represents the highest contribution with 91.5%. It is concluded that that experience management is a tool when strategies are implemented, when experience processes are established, and when the service is designed

Spatial distribution and incidence of dengue cases: an analysis of the situation in Medellín, Colombia

ABSTRACT: To analyze the spatial distribution of dengue cases and the incidence of this disease. Methodology: 17.400 dengue cases were spatially located by means of the addresses of patients which were reported by Data Generating Primary Units to the Medellin Office of the Health Secretary from 2007 to 2011. Dengue incidences were calculated and geospatially ranked with the ArcGIS 9.3 software, and they were categorized by risk level according to the Pan American Health Organization. Results and Discussion: the disease was distributed heterogeneously throughout the various neighborhoods of the city. The years 2007 and 2010 had the highest number of cases, thus being epidemic years; the other years showing an endemic behavior. In 2007 none of the neighborhoods was in very high risk category; however, in 2010, 49 neighborhoods were placed inside this category. As for endemic years according to dengue incidence, of the 249 neighborhoods of the city, just two of them were found in high risk in 2008 and 2009, but none in 2011. Moreover, a large percentage of neighborhoods in these years were considered to be in the low risk category."RESUMEN:Analizar la distribución espacial de los casos y la incidencia de dengue. Metodología: se ubicaron espacialmente 17.400 casos de dengue notificados por las Unidades Primarias Generadoras de Datos a la Secretaría de Salud de Medellín en el período 2007 a 2011 a través de las direcciones de las viviendas de los pacientes. Se calcularon las incidencias y se ubicaron geoespacialmente utilizando el software ArcGis 9,3, categorizándolas por niveles de riesgo según la Organización Panamericana de la Salud. Resultados y discusión: la enfermedad se distribuyó heterogéneamente en los diferentes barrios de la ciudad. Los años 2007 y 2010 presentaron el mayor número de casos, correspondiendo a años epidémicos, mientras que los demás años mostraron un comportamiento endémico. En el 2007 ningún barrio se ubicó en la categoría riesgo muy alto, pero sí 49 localidades para el año 2010. Para los años endémicos según la incidencia de dengue, de los 249 barrios de la ciudad, en los años 2008 y 2009, solo dos se encontraron en riesgo alto y ninguno para 2011, y un gran porcentaje de barrios en estos años se ubicaron en riesgo bajo."RESUMEN:Analizar la distribución espacial de los casos y la incidencia de dengue. Metodología: se ubicaron espacialmente 17.400 casos de dengue notificados por las Unidades Primarias Generadoras de Datos a la Secretaría de Salud de Medellín en el período 2007 a 2011 a través de las direcciones de las viviendas de los pacientes. Se calcularon las incidencias y se ubicaron geoespacialmente utilizando el software ArcGis 9,3, categorizándolas por niveles de riesgo según la Organización Panamericana de la Salud. Resultados y discusión: la enfermedad se distribuyó heterogéneamente en los diferentes barrios de la ciudad. Los años 2007 y 2010 presentaron el mayor número de casos, correspondiendo a años epidémicos, mientras que los demás años mostraron un comportamiento endémico. En el 2007 ningún barrio se ubicó en la categoría riesgo muy alto, pero sí 49 localidades para el año 2010. Para los años endémicos según la incidencia de dengue, de los 249 barrios de la ciudad, en los años 2008 y 2009, solo dos se encontraron en riesgo alto y ninguno para 2011, y un gran porcentaje de barrios en estos años se ubicaron en riesgo bajo

Stainless steel weld metal designed to mitigate residual stresses

There have been considerable efforts to create welding consumables which on solid state phase transformation partly compensate for the stresses which develop when a constrained weld cools to ambient temperatures. All of these efforts have focused on structural steels which are ferritic. In the present work, alloy design methods have been used to create a stainless steel welding consumable which solidifies as δ ferrite, transforms almost entirely into austenite which then undergoes martensitic transformation at a low temperature of about 220◦C. At the same time, the carbon concentration has been kept to a minimum to avoid phenomena such as sensitisation. The measured mechanical properties, especially toughness, seem to be significantly better than commercially available martensitic stainless steel welding consumables, and it has been demonstrated that the use of the new alloy reduces distortion in the final joint

Characterization of Schistosome Tegumental Alkaline Phosphatase (SmAP)

Schistosomes are parasitic platyhelminths that currently infect over 200 million people globally. The parasites can live for years in a putatively hostile environment - the blood of vertebrates. We have hypothesized that the unusual schistosome tegument (outer-covering) plays a role in protecting parasites in the blood; by impeding host immunological signaling pathways we suggest that tegumental molecules help create an immunologically privileged environment for schistosomes. In this work, we clone and characterize a schistosome alkaline phosphatase (SmAP), a predicted ∼60 kDa glycoprotein that has high sequence conservation with members of the alkaline phosphatase protein family. The SmAP gene is most highly expressed in intravascular parasite life stages. Using immunofluorescence and immuno-electron microscopy, we confirm that SmAP is expressed at the host/parasite interface and in internal tissues. The ability of living parasites to cleave exogenous adenosine monophosphate (AMP) and generate adenosine is very largely abolished when SmAP gene expression is suppressed following RNAi treatment targeting the gene. These results lend support to the hypothesis that schistosome surface enzymes such as SmAP could dampen host immune responses against the parasites by generating immunosuppressants such as adenosine to promote their survival. This notion does not rule out other potential functions for the adenosine generated e.g. in parasite nutrition

Transcriptional Changes in Schistosoma mansoni during Early Schistosomula Development and in the Presence of Erythrocytes

Schistosome blood flukes cause more mortality and morbidity than any other human worm infection, but current control methods primarily rely on a single drug. There is a desperate need for new approaches to control this parasite, including vaccines. People become infected when the free-swimming larva, the cercaria, enters through the skin and becomes the schistosomulum. Schistosomula are susceptible to immune responses during their first few days in the host before they become adult parasites. We characterised the genes that these newly transformed parasites switch on when they enter the host to identify molecules that are critical for survival in the human host. Some of these highly up-regulated genes can be targeted for future development of new vaccines and drugs

Gestión del conocimiento. Perspectiva multidisciplinaria. Volumen 10

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, Volumen 10, de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro es una publicación internacional, seriada, continua, arbitrada de acceso abierto a todas las áreas del conocimiento, que cuenta con el esfuerzo de investigadores de varios países del mundo, orientada a contribuir con procesos de gestión del conocimiento científico, tecnológico y humanístico que consoliden la transformación del conocimiento en diferentes escenarios, tanto organizacionales como universitarios, para el desarrollo de habilidades cognitivas del quehacer diario. La gestión del conocimiento es un camino para consolidar una plataforma en las empresas públicas o privadas, entidades educativas, organizaciones no gubernamentales, ya sea generando políticas para todas las jerarquías o un modelo de gestión para la administración, donde es fundamental articular el conocimiento, los trabajadores, directivos, el espacio de trabajo, hacia la creación de ambientes propicios para el desarrollo integral de las instituciones