3D multiphysics model for the simulation of electrochemical machining of stainless steel (SS316)

In Electrochemical Machining (ECM) - a method that uses anodic dissolution to remove metal - it is extremely difficult to predict material removal and resulting surface finish due to the complex interaction between the numerous parameters available in the machining conditions. In this paper, it is argued that a 3D coupled multiphysics finite element model is a suitable way to further develop the ability to model the ECM process. This builds on the work of previous researchers and further claims that the over-potential available at the surface of the workpiece is a crucial factor in ensuring satisfactory results. As a validation example, a real world problem for polishing via ECM of SS316 pipes is modelled and compared to empirical tests. Various physical and chemical effects, including those due to electrodynamics, fluid dynamic, and thermal and electrochemical phenomena were incorporated in the 3D geometric model of the proposed tool, workpiece and electrolyte. Predictions were made for current density, conductivity, fluid velocity, temperature, and crucially, with estimates of the deviations in over-potential. Results revealed a good agreement between simulation and experiment and these were sufficient to solve the immediate real problem presented but also to ensure that future additions to the technique could in the longer term lead to a better means of understanding a most useful manufacturing process

Coleman-Weinberg mechanism in a three-dimensional supersymmetric Chern-Simons-matter model

Using the superfield formalism, we study the dynamical breaking of gauge symmetry in the N=1 three-dimensional supersymmetric Chern-Simons model, coupled to a complex scalar superfield with a quartic self-coupling. This is an analogue of the conformally invariant Coleman-Weinberg model in four spacetime dimensions. We show that a mass for the gauge and matter superfields are dynamically generated after two-loop corrections to the effective superpotential. We also discuss the N=2 extension of our work, showing that the Coleman-Weinberg mechanism in such model is not feasible, because it is incompatible with perturbation theory.Comment: 14 pages, 2 figures. Minor corrections, references added. Journal versio

Lesiones y problemas físicos padecidos por senderistas y cicloturistas en una ruta por etapas: el caso del Camino de Santiago

Este trabajo ha tenido por objetivo conocer los problemas físicos, dolencias o enfermedades padecidas por el peregrino mayor de 15 años que recorre el Camino de Santiago, andando o en bicicleta, analizando las diferencias producidas en función de la edad, sexo, medio de locomoción y nacionalidad. La investigación se ha desarrollado mediante la aplicación de un cuestionario autoadministrado en Compostela a una muestra de 1.091 sujetos, utilizando el procedimiento de muestreo estratificado polietápico con afijación proporcional, con un margen de error muestral del ±3 % y un nivel de confianza del 95,5%. Los resultados indicaron que el medio utilizado para realizar una ruta por etapas, y la distancia recorrida, son determinantes de los problemas físicos sufridos, comprobándose que las ampollas y las llagas en los pies, así como la tendinitis, las padecen más los senderistas, mientras que a los cicloturistas afectan más las insolaciones, resfriados y caídas y golpes

Geotechnical Aspects on Seismic Risk Assessment in Cusco, Peru

Results from many efforts to better understand the nature of ground motions and the seismic behavior or structures in Cusco, Peru, give now the possibility to combine several sources of information to produce estimates of seismic hazard and risk. A model is presented which estimates expected damage, based on geotechnical characteristics and intensity-damage relations derived for several types of buildings representative of Cusco’s constructions. The study area was divided into smaller sections covering the whole city. This information, along with the geographic distribution of soil types and construction density, allows computation of expected losses during a given event for sites distributed throughout the city

Dynamical (super)symmetry vacuum properties of the supersymmetric Chern-Simons-matter model

By computing the two-loop effective potential of the D=3 N=1 supersymmetric Chern-Simons model minimally coupled to a massless self-interacting matter superfield, it is shown that supersymmetry is preserved, while the internal U(1) and the scale symmetries are broken at two-loop order, dynamically generating masses both for the gauge superfield and for the real component of the matter superfield.Comment: revtex4, 12 pages, 2 figures, journal versio

Mechanical chest compression devices improve survival of liver grafts from donors after cardiac death.

pre-print107 K

Measurement of 1323 and 1487 keV resonances in 15N({\alpha}, {\gamma})19F with the recoil separator ERNA

The origin of fluorine is a widely debated issue. Nevertheless, the ^{15}N({\alpha},{\gamma})^{19}F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the DC component and the tails of the two broad resonances at E_{c.m.} = 1323 and 1487 keV. Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m. = 1323 and 1487 keV is used to determine their widths in the {\alpha} and {\gamma} channels. We show that a direct measurement of the cross section of the ^{15}N({\alpha},{\gamma})^{19}F reaction can be successfully obtained with the Recoil Separator ERNA, and the widths {\Gamma}_{\gamma} and {\Gamma}_{\alpha} of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance {\Gamma}_{\alpha} . The revision of the widths of the two more relevant broad resonances in the 15N({\alpha},{\gamma})19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the ^{19}F stellar nucleosynthesis is dominated by the uncertainties affecting the Direct Capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.Comment: 8 pages, 11 figures. Accepted for publication in PR

Possible Patient Early Diagnosis by Ultrasonic Noninvasive Estimation of Thermal Gradients into Tissues Based on Spectral Changes Modeling

To achieve a precise noninvasive temperature estimation, inside patient tissues, would open promising research fields, because its clinic results would provide early-diagnosis tools. In fact, detecting changes of thermal origin in ultrasonic echo spectra could be useful as an early complementary indicator of infections, inflammations, or cancer. But the effective clinic applications to diagnosis of thermometry ultrasonic techniques, proposed previously, require additional research. Before their implementations with ultrasonic probes and real-time electronic and processing systems, rigorous analyses must be still made over transient echotraces acquired from well-controlled biological and computational phantoms, to improve resolutions and evaluate clinic limitations. It must be based on computing improved signal-processing algorithms emulating tissues responses. Some related parameters in echo-traces reflected by semiregular scattering tissues must be carefully quantified to get a precise processing protocols definition. In this paper, approaches for non-invasive spectral ultrasonic detection are analyzed. Extensions of author's innovations for ultrasonic thermometry are shown and applied to computationally modeled echotraces from scattered biological phantoms, attaining high resolution (better than 0.1°C). Computer methods are provided for viability evaluation of thermal estimation from echoes with distinct noise levels, difficult to be interpreted, and its effectiveness is evaluated as possible diagnosis tool in scattered tissues like liver