DISEÑO DE UN DISPOSITIVO PARA LA MEDICIÓN DE ESFUERZOS RESIDUALES

En este artículo se presenta el diseño de un dispositivo para la de medición de esfuerzos residuales con movimientos programables en secuencia, en probetas de aluminio utilizando el método del barreno ciego. La propuesta final del instrumento se desarrolló utilizando la metodología de Pahl y Beitz, la cual comprende los pasos en la planeación y proceso de diseño, así como la identificación esencial del problema dentro de una lista de requerimientos y la identificación de la función general y subfunciones de la misma. En ésta metodología se utiliza la tabla de clasificación de las funciones básicas que pueden satisfacer a la matriz morfológica. Finalmente se evalúan las propuestas, y se una selecciona una solución potencial. El resultado que se obtiene en este trabajo, es una actualización al típico instrumento del barreno ciego y al medidor de análisis de esfuerzos P3 de la compañía Micro Measurements, donde los cambios principales se enfocan en el centrado electrónico de la probeta y la obtención de los resultados en una pantalla de visualización, de acuerdo a la norma ASTM 837-08.Palabra(s) Clave(s): Barreno ciego, medición de esfuerzos, norma ASTM E 837-08, procesamiento de la información, sistema de visión y visualización de resultados

DESARROLLO DE UN DISPOSITIVO DE ENSAYOS MINIATURA DE PUNZONAMIENTO PARA DETERMINAR PROPIEDADES MECÁNICAS DE ACERO DE BAJA ALEACIÓN AL CROMO-NÍQUEL DEL ANCLAJE DE UN PUENTE (PUNCHING SHEAR MINIATURE TESTING DEVICE TO DETERMINE THE MECHANICAL PROPERTIES OF LOW CHROME-NICKEL STEEL OF A BRIDGE ANCHOR)

El conocer las propiedades mecánicas de un elemento estructural en servicio es fundamental para prevenir alguna posible falla, sin embargo una problemática que se puede presentar es la limitación de material necesario para fabricar las probetas bajo las normas convencionales. Por lo que es importante contar con un ensayo alternativo que permita determinar las propiedades de tensión empleando muestras pequeñas de material. En el presente trabajo se da a conocer el diseño y fabricación de un dispositivo para la técnica de ensayos miniatura de punzonamiento con el fin de evaluar las propiedades a tensión de un anclaje de acero de baja aleación al cromo-níquel de un puente atirantado ubicado en el Golfo de México. Con el dispositivo se busca extender el uso de la técnica y caracterizar otros materiales de elementos mecánicos donde se tenga como limitación la disponibilidad de material. Con la fabricación de los utillajes se pudo observar las ventajas de la prueba de punzonamiento miniatura y mediante la comparación de los resultados obtenidos se considera a los elementos, como satisfactorios en su servicio.Palabras clave: ensayo miniatura de punzonamiento, propiedades de tensión, acero colado, anclaje de acero cromo níquel. AbstractKnowing the mechanical properties of a structural element in service is essential to prevent any possible failure, however a problem that may arise is the limitation of material needed to manufacture the specimens under conventional standards. Therefore it is important to have an alternative test that allows to determine the tensile properties using small samples of material. In the present work, the design and manufacture of a device for the technique of miniature punching tests is presented in order to evaluate the tensile properties of a low alloy steel anchor to the chrome-nickel of a cable-stayed bridge located in the Gulf of Mexico. The device seeks to extend the use of the technique and characterize other materials of mechanical elements where the availability of material is limited. With the manufacture of the tools, the advantages of the miniature punching test were observed and by comparing the results obtained, the elements are considered as satisfactory in their service.Keywords: miniature punching shear test, tensile properties, cast steel, chromium nickel steel anchor

Métodos y técnicas de monitoreo y predicción temprana en los escenarios de riesgos socionaturales

Esta obra concentra los métodos y las técnicas fundamentales para el seguimiento y monitoreo de las dinámicas de los escenarios de riesgos socionaturales (geológicos e hidrometeorológicos) y tiene como objetivo general orientar, apoyar y acompañar a los directivos y operativos de protección civil en aterrizar las acciones y políticas públicas enfocadas a la gestión del riesgo local de desastre

Evidence of spatial clustering of childhood acute lymphoblastic leukemia cases in Greater Mexico City: report from the Mexican Inter-Institutional Group for the identification of the causes of childhood leukemia

BackgroundA heterogeneous geographic distribution of childhood acute lymphoblastic leukemia (ALL) cases has been described, possibly, related to the presence of different environmental factors. The aim of the present study was to explore the geographical distribution of childhood ALL cases in Greater Mexico City (GMC).MethodsA population-based case-control study was conducted. Children <18 years old, newly diagnosed with ALL and residents of GMC were included. Controls were patients without leukemia recruited from second-level public hospitals, frequency-matched by sex, age, and health institution with the cases. The residence address where the patients lived during the last year before diagnosis (cases) or the interview (controls) was used for geolocation. Kulldorff’s spatial scan statistic was used to detect spatial clusters (SCs). Relative risks (RR), associated p-value and number of cases included for each cluster were obtained.ResultsA total of 1054 cases with ALL were analyzed. Of these, 408 (38.7%) were distributed across eight SCs detected. A relative risk of 1.61 (p<0.0001) was observed for the main cluster. Similar results were noted for the remaining seven ones. Additionally, a proximity between SCs, electrical installations and petrochemical facilities was observed.ConclusionsThe identification of SCs in certain regions of GMC suggest the possible role of environmental factors in the etiology of childhood ALL

Table_1_Evidence of spatial clustering of childhood acute lymphoblastic leukemia cases in Greater Mexico City: report from the Mexican Inter-Institutional Group for the identification of the causes of childhood leukemia.xlsx

BackgroundA heterogeneous geographic distribution of childhood acute lymphoblastic leukemia (ALL) cases has been described, possibly, related to the presence of different environmental factors. The aim of the present study was to explore the geographical distribution of childhood ALL cases in Greater Mexico City (GMC).MethodsA population-based case-control study was conducted. Children ResultsA total of 1054 cases with ALL were analyzed. Of these, 408 (38.7%) were distributed across eight SCs detected. A relative risk of 1.61 (pConclusionsThe identification of SCs in certain regions of GMC suggest the possible role of environmental factors in the etiology of childhood ALL.</p

NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics

Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data