Electropulsing effects on mechanical and metallurgical behavior of AISI-SAE 4140 steel

The electroplasticity phenomenon (EP) produces changes in the mechanical properties of a metal, due to the simultaneous application of mechanical stresses of compression, bending, etc., and high instantaneous current pulses. The changes produced on the plastic deformation rate by the EP are due to thermal effects (such as Joule effect) and other effects associated to the electric and magnetic fields. There are only a few studies that consider, as this paper does, the effects of electropulsing effect on tensile test processes in which the electron flow is esteemed as the main reason. In this paper, the results of a research on tensile test on specimen of AISI-SAE 4140, assisted by high-current-density electric pulses are presented. The aim is to evaluate the effect of these pulses on the microstructure and mechanical properties of metallic materials. The phase transformations and microstructural changes in the metallic specimens exposed to EP were analysed using Scanning Electron Microscopy (SEM), Diffraction Ray X (DRX) and Differential Scanning Calorimetry (DSC). Preliminary results show there are some differences in the material behaviour, between the specimens tensile tested with and without EP, such as: decreases values of yield and ultimate strength and XRD analyses attests to a slight displacement and intensity reduction of diffraction. Moreover, the application of current density in the order of 2.18 A/mm² is enough to produce changes in mechanical and metallographic properties of AISI/SAE 4140.Peer ReviewedPostprint (published version

La formación continua en la docencia: piedra angular para la educación del futuro

This study examines teachers' perception and experience with continuing education, using a quantitative methodology with surveys applied to 51 teachers from different educational levels. Participation in training programs, areas of interest, barriers to participation, and impact on teaching practice were investigated. The results indicate a high valuation of continuing education, with 86.3% participating and 88.2% reporting positive changes in their practice as a result of this training. The main areas of interest are innovative methodologies and the use of technologies. However, barriers such as lack of time, high costs, and lack of information about the programs were identified. The study concludes that lifelong learning is crucial for professional development and educational improvement, highlighting the need to overcome existing barriers to facilitate access to these opportunities.Este estudio examina la percepción y experiencia de los docentes con la formación continua, utilizando una metodología cuantitativa con encuestas aplicadas a 51 docentes de diferentes niveles educativos. Se investigó la participación en programas de formación, áreas de interés, barreras para la participación y el impacto en la práctica docente. Los resultados indican una alta valoración de la formación continua, con un 86,3% de participación y un 88,2% reportando cambios positivos en su práctica como resultado de esta formación. Las principales áreas de interés son las metodologías innovadoras y el uso de tecnologías. Sin embargo, se identificaron barreras como la falta de tiempo, costos elevados y falta de información sobre los programas. El estudio concluye que la formación continua es crucial para el desarrollo profesional y la mejora educativa, destacando la necesidad de superar las barreras existentes para facilitar el acceso a estas oportunidades

A search for an unexpected asymmetry in the production of e(+)mu(-) and e(-)mu(+) pairs in proton-proton collisions recorded by the ATLAS detector at root s=13 TeV

This search, a type not previously performed at ATLAS, uses a comparison of the production cross sections for e(+)mu(-) and e(-)mu(+) pairs to constrain physics processes beyond the Standard Model. It uses 139 fb(-1) of proton-proton collision data recorded at root s = 13 TeV at the LHC. Targeting sources of new physics which prefer final states containing e(+)mu(-) and e(-)mu(+), the search contains two broad signal regions which are used to provide model-independent constraints on the ratio of cross sections at the 2% level. The search also has two special selections targeting supersymmetric models and leptoquark signatures. Observations using one of these selections are able to exclude, at 95% confidence level, singly produced smuons with masses up to 640 GeV in a model in which the only other light sparticle is a neutralino when the R-parity-violating coupling lambda(23)(1)' is close to unity. Observations using the other selection exclude scalar leptoquarks with masses below 1880 GeV when g(1R)(eu) = g(1R)(mu c) = 1, at 95% confidence level. The limit on the coupling reduces to g(1R)(eu) = g(1R)(mu c) = 0.46 for a mass of 1420 GeV

Search for tt¯ resonances in fully hadronic final states in pp collisions at √s = 13 TeV with the ATLAS detector

This paper presents a search for new heavy particles decaying into a pair of top quarks using 139 fb of proton-proton collision data recorded at a centre-of-mass energy of s = 13 TeV with the ATLAS detector at the Large Hadron Collider. The search is performed using events consistent with pair production of high-transverse-momentum top quarks and their subsequent decays into the fully hadronic final states. The analysis is optimized for resonances decaying into a tt¯ pair with mass above 1.4 TeV, exploiting a dedicated multivariate technique with jet substructure to identify hadronically decaying top quarks using large-radius jets and evaluating the background expectation from data. No significant deviation from the background prediction is observed. Limits are set on the production cross-section times branching fraction for the new Z′ boson in a topcolor-assisted-technicolor model. The Z′ boson masses below 3.9 and 4.7 TeV are excluded at 95% confidence level for the decay widths of 1% and 3%, respectively. [Figure not available: see fulltext.

Matemáticas en contexto

El libro compila estrategias didácticas derivadas del programa de formación complementario escritas por instructores técnicos de diferentes regionales del país, describe la forma en que se incorpora el conocimiento matemático en campos específicos de diferentes áreas de formación laboral basado en las teorías didácticas y reflexiones pedagógicas de instructores.The book compiles the didactic strategies derived from the complementary training program by the technical instructors of the regional media of the country, describes the way in which mathematical knowledge is incorporated in the fields of different areas of work training based on theories didactic and pedagogical reflections of instructors.Consideraciones frente al aprendizaje de las matemáticas -- Perspectiva constructivista -- Teoría de las situaciones didácticas -- Modelación matemática -- Mediación tecnológica -- Pensamiento numérico variacional -- Pensamiento numérico -- Pensamiento variacional -- Diseño de modelo matemático con aplicación de costos de producción -- Modelo matemático del consumo de gas en un artefacto afectado por su presión de trabajo -- Planeación de la producción agrícola: Caso plan óptimo de siembra que permita alcanzar la máxima rentabilidad del cultivo -- Estudio del Álgebra de Boole -- Diseño de un modelo de inventarios para una pequeña empresa de calzado de dotación -- Estudio de la Ley de Ohm mediante herramienta interactiva -- Pensamiento métrico-geométrico -- Pensamiento geométrico -- Pensamiento métrico -- Caso de optimización de recursos en el sector industrial de la confección -- Optimización de espacios para huertas urbanas -- Optimización de los costos del espacio de almacenamiento en microempresas y pequeñas empresas de acuerdo con las normas de seguridad vigentes -- Unidad de medida métrica para confección de ropa exterior femenina -- Optimización de recursos aplicando el proceso administrativo -- Pensamiento aleatorio -- Estadística Básica para Articulación con la Media -- Evaluación del impacto de la accidentalidad en la implementación del Sistema de Gestión de Seguridad y Salud en el Trabajo (sg-sst) por medio de indicadores -- Identificar los aspectos de la declaración de renta para una persona natural no obligada a llevar contabilidad -- Fortalecimiento de la estadística: caso de las unidades productivas del Centro de Biotecnología Agropecuaria -- Estadística dinámica -- Resultados preliminaresna[270 páginas

Measurement of isolated-photon plus two-jet production in pp collisions at √s = 13 TeV with the ATLAS detector

The dynamics of isolated-photon plus two-jet production in pp collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset corresponding to an integrated luminosity of 36.1 fb. Cross sections are measured as functions of a variety of observables, including angular correlations and invariant masses of the objects in the final state, γ + jet + jet. Measurements are also performed in phase-space regions enriched in each of the two underlying physical mechanisms, namely direct and fragmentation processes. The measurements cover the range of photon (jet) transverse momenta from 150 GeV (100 GeV) to 2 TeV. The tree-level plus parton-shower predictions from Sherpa and Pythia as well as the next-to-leading-order QCD predictions from Sherpa are compared with the measurements. The next-to-leading-order QCD predictions describe the data adequately in shape and normalisation except for regions of phase space such as those with high values of the invariant mass or rapidity separation of the two jets, where the predictions overestimate the data. [Figure not available: see fulltext.

Measurements of top-quark pair differential and double-differential cross-sections in the l plus jets channel with pp collisions at root s=13 TeV using the ATLAS detector

Single- and double-differential cross-section measurements are presented for the production of top-quark pairs, in the lepton + jets channel at particle and parton level. Two topologies, resolved and boosted, are considered and the results are presented as a function of several kinematic variables characterising the top and t t system and jet multiplicities. The study was performed using data from pp collisions at centre-of-mass energy of 13 TeV collected in 2015 and 2016 by the ATLAS detector at the CERN Large Hadron Collider (LHC), corresponding to an integrated luminosity of 36 fb-1. Due to the large tt cross-section at the LHC, such measurements allow a detailed study of the properties of top-quark production and decay, enabling precision tests of several Monte Carlo generators and fixed-order Standard Model predictions. Overall, there is good agreement between the theoretical predictions and the data

Measurement of the inclusive isolated-photon cross section in pp collisions at √s = 13 TeV using 36 fb−1 of ATLAS data

The differential cross section for isolated-photon production in pp collisions is measured at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC using an integrated luminosity of 36.1 fb. The differential cross section is presented as a function of the photon transverse energy in different regions of photon pseudorapidity. The differential cross section as a function of the absolute value of the photon pseudorapidity is also presented in different regions of photon transverse energy. Next-to-leading-order QCD calculations from Jetphox and Sherpa as well as next-to-next-to-leading-order QCD calculations from Nnlojet are compared with the measurement, using several parameterisations of the proton parton distribution functions. The predictions provide a good description of the data within the experimental and theoretical uncertainties. [Figure not available: see fulltext.