Sensitivity analysis of the input parameters of a physical based ductile failure model of Ti-6Al-4V for the prediction of surface integrity

In machining of Ti-6Al-4V, it is commonly reported the appearance of segmented chip produced by adiabatic shearing (at high cutting speeds) and lack of ductility (at low cutting speeds). Moreover, machining is a manufacturing process that is based on applying external energy to the workpiece to produce a separation of a material layer. Thus, to analyze the physics involved in the new surface generation and in the chip segmentation process, it is necessary to apply ductile failure models. However, the characterization of fracture models in machining conditions (temperature, strain rate, stress triaxiality, Lode angle etc.) is an arduous task. Therefore, to define a ductile failure model applicable to machining it is almost inevitable to apply inverse simulations strategies to obtain reliable results in the not tested conditions. Nevertheless, there is few information about the influence of the input parameters of ductile failure model in fundamental outputs and even less in surface integrity aspects. The aim of this research was to conduct a sensitivity analysis of the influence of the input parameters of a physical based ductile failure model not only in fundamental variables (forces, temperatures and chip morphology) but also on surface integrity (surface drag). To this end, a subroutine was developed for the ductile failure model and it was implemented in the Finite Element Method (FEM) software AdvantEdge. Subsequently, using a statistical software and the Design of Experiments (DOE) technique the influence of the input parameters of the failure model on the outputs was analyzed

Nonlinear interfacial waves in a constant-vorticity planar flow over variable depth

Exact Lagrangian in compact form is derived for planar internal waves in a two-fluid system with a relatively small density jump (the Boussinesq limit taking place in real oceanic conditions), in the presence of a background shear current of constant vorticity, and over arbitrary bottom profile. Long-wave asymptotic approximations of higher orders are derived from the exact Hamiltonian functional in a remarkably simple way, for two different parametrizations of the interface shape.Comment: revtex, 4.5 pages, minor corrections, summary added, accepted to JETP Letter

Boltzmann equation and hydrodynamic fluctuations

We apply the method of invariant manifolds to derive equations of generalized hydrodynamics from the linearized Boltzmann equation and determine exact transport coefficients, obeying Green-Kubo formulas. Numerical calculations are performed in the special case of Maxwell molecules. We investigate, through the comparison with experimental data and former approaches, the spectrum of density fluctuations and address the regime of finite Knudsen numbers and finite frequencies hydrodynamics.Comment: This is a more detailed version of a related paper: I.V. Karlin, M. Colangeli, M. Kroger, PRL 100 (2008) 214503, arXiv:0801.2932. It contains comparison between predictions and experiment, in particular. 11 pages, 6 figures, 2 table

Numerical Methods for the Stochastic Landau-Lifshitz Navier-Stokes Equations

The Landau-Lifshitz Navier-Stokes (LLNS) equations incorporate thermal fluctuations into macroscopic hydrodynamics by using stochastic fluxes. This paper examines explicit Eulerian discretizations of the full LLNS equations. Several CFD approaches are considered (including MacCormack's two-step Lax-Wendroff scheme and the Piecewise Parabolic Method) and are found to give good results (about 10% error) for the variances of momentum and energy fluctuations. However, neither of these schemes accurately reproduces the density fluctuations. We introduce a conservative centered scheme with a third-order Runge-Kutta temporal integrator that does accurately produce density fluctuations. A variety of numerical tests, including the random walk of a standing shock wave, are considered and results from the stochastic LLNS PDE solver are compared with theory, when available, and with molecular simulations using a Direct Simulation Monte Carlo (DSMC) algorithm

A diffusive system driven by a battery or by a smoothly varying field

We consider the steady state of a one dimensional diffusive system, such as the symmetric simple exclusion process (SSEP) on a ring, driven by a battery at the origin or by a smoothly varying field along the ring. The battery appears as the limiting case of a smoothly varying field, when the field becomes a delta function at the origin. We find that in the scaling limit, the long range pair correlation functions of the system driven by a battery turn out to be very different from the ones known in the steady state of the SSEP maintained out of equilibrium by contact with two reservoirs, even when the steady state density profiles are identical in both models

Compression and post-buckling damage growth and collapse analysis of flat composite stiffened panels

Experimental and numerical investigations were conducted into the damage growth and collapse behaviour of composite blade-stiffened structures. Four panel types were tested, consisting of two secondary-bonded skin-stiffener designs in both undamaged and pre-damaged configurations. The pre-damaged configurations were manufactured by replacing the skin-stiffener adhesive with a centrally located, full-width Teflon strip. All panels were loaded in compression to collapse, which was characterised by complex post-buckling deformation patterns and ply damage, particularly in the stiffener. For the pre-damaged panels, significant crack growth was seen in the skin-stiffener interface prior to collapse, which caused a reduction in load-carrying capacity. In the numerical analysis of the undamaged panels, collapse was predicted using a ply failure degradation model, and a global-local approach that monitored a strength-based criterion in the skin-stiffener interface. The pre-damaged models were analysed with ply degradation and a method for capturing interlaminar crack growth based on multi-point constraints controlled using the Virtual Crack Closure Technique. The numerical approach gave close correlation with experimental results, and allowed for an in-depth analysis of the damage growth and failure mechanisms contributing to panel collapse. The successful prediction of collapse under the combination of deep post-buckling deformations and several composite damage mechanisms has application for the next generation of composite aircraft designs

Cambio de uso de suelo, vegetación y tenencia de la tierra en la Sierra de Sonora en el contexto de la minería de litio

Las actividades mineras extractivas son de gran importancia económica para México pues desde hace algunos siglos nuestro país ha sido un importante lugar de extracción de recursos naturales, aunque en muchas ocasiones esa relevancia económica no se ve reflejada en todos los actores involucrados, sino que se concentran en unos cuantos que acaparan la actividad y el mercado en torno a ella. El estado de Sonora es la entidad más importante del país para este tipo de actividad, la minería, sin embargo, muchas comunidades que se encuentran inmersas en los centros mineros no gozan de los beneficios que ésta deja, por el contrario, son las que comúnmente sufren las repercusiones negativas en términos socioambientales. En este contexto y a partir del conocimiento de una serie de yacimientos de litio en la Sierra de Sonora, es importante conocer las características socioambientales de la región para tener un panorama más amplio de cómo se encuentra y cuáles son las condiciones de las comunidades y del ecosistema y así poder establecer cuáles serán las posibles implicaciones una vez que inicien los trabajos de explotación del mineral. Los seis municipios que comprenden este trabajo: Bacadéhuachi, Divisaderos, Granados, Huásabas, Nácori Chico y Sahuaripa, cuentan con concesiones de litio, ya sea vigentes o en trámite, lo que implica que en el futuro cercano y debido a la demanda mundial del mineral, serán zonas de gran importancia. Ante ello, cabe preguntarse si los supuestos beneficios derivados de la extracción podrán mejorar la vida de las comunidades y de qué manera impactarán en la región. El objetivo de este trabajo es, por un lado, abordar las generalidades y los impactos potenciales de la minería de litio en nuestro país; analizar el cambio en el uso de suelo, la cobertura vegetal y la tenencia de la tierra; así como la presencia de dos Regiones Terrestres Prioritarias en la Sierra de Sonora y las concesiones mineras en ellas, sobre todo de litio, en el área de estudio. En el mismo sentido, se analizan ciertos aspectos del marco legal vigente, algunas de las modificaciones en la última reforma a la Ley Minera y la relación de estos cambios con las transformaciones en el uso de suelo en los últimos años

The Climate-system Historical Forecast Project: providing open access to seasonal forecast ensembles from centers around the globe

Fil: Tompkins, Adrian M.. The Abdus Salam; ItaliaFil: Ortiz de Zarate, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Saurral, Ramiro Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Vera, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Saulo, Andrea Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; ArgentinaFil: Merryfield, William J.. Canadian Centre for Climate Modelling and Analysis; CanadáFil: Sigmond, Michael. Canadian Centre for Climate Modelling and Analysis; CanadáFil: Lee, Woo Sung. Canadian Centre for Climate Modelling and Analysis; CanadáFil: Baehr, Johanna. Universitat Hamburg; AlemaniaFil: Braun, Alain. Météo-France; FranciaFil: Amy Butler. National Ocean And Atmospheric Administration; Estados UnidosFil: Déqué, Michel. Météo-France; FranciaFil: Doblas Reyes, Francisco J.. Institució Catalana de Recerca i Estudis Avancats; España. Barcelona Supercomputing Center - Centro Nacional de Supercomputacion; EspañaFil: Gordon, Margaret. Met Office; Reino UnidoFil: Scaife, Adam A.. University of Exeter; Reino UnidoFil: Yukiko Imada. Japan Meteorological Agency. Meteorological Research Institute. Climate Research Department; JapónFil: Masayoshi Ishii. Japan Meteorological Agency. Meteorological Research Institute. Climate Research Department; JapónFil: Tomoaki Ose. Japan Meteorological Agency. Meteorological Research Institute. Climate Research Department; JapónFil: Kirtman, Ben. University of Miami; Estados UnidosFil: Kumar, Arun. National Ocean And Atmospheric Administration; Estados UnidosFil: Müller, Wolfgang A.. Max-Planck-Institut für Meteorologie; AlemaniaFil: Pirani, Anna. Université Paris-Saclay; FranciaFil: Stockdale, Tim. European Centre for Medium-Range Weather; Reino UnidoFil: Rixen, Michel. World Meteorological Organization. World Climate Research Programme; SuizaFil: Yasuda, Tamaki. Japan Meteorological Agency. Climate Prediction Division; Japó

DNA-based population density estimation of black bear at northern Mexico: A preliminary study

The analysis of deoxyribonucleic acid (DNA) microsatellites from hair samples obtained by the non-invasive method of traps was used to estimate the population density of black bears (Ursus americanus eremicus) in a mountain located at the county of Lampazos, Nuevo Leon, Mexico. The genotyping of bears was performed by multiplex polymerase chain reaction (PCR) using an average of two hairs for each animal. Samples were obtained with barbed wire placed at the traps, which contained food as bait. Multiplex PCR was performed with the GenomiPhiTM, G.E. kit and genotyping with an automated DNA sequencing machine (ABI 310 System). Allelic frequency, heterozygosis and exclusion probability of seven DNA microsatellites were calculated and analyzed with computer programs to determine the population density. Three of the microsatellites had a heterozygosis higher than 0.7 and the population density was calculated in at least 1 bear/km2.Keywords: Black bear, Ursus americanus, population size, DNA microsatellite, MexicoAfrican Journal of Biotechnology Vol. 12(2), pp. 103-10

From Therapeutic Factors to Mechanisms of Change in the Creative Arts Therapies:A Scoping Review

Empirical studies in the creative arts therapies (CATs; i.e., art therapy, dance/movement therapy, drama therapy, music therapy, psychodrama, and poetry/bibliotherapy) have grown rapidly in the last 10 years, documenting their positive impact on a wide range of psychological and physiological outcomes (e.g., stress, trauma, depression, anxiety, and pain). However, it remains unclear how and why the CATs have positive effects, and which therapeutic factors account for these changes. Research that specifically focuses on the therapeutic factors and/or mechanisms of change in CATs is only beginning to emerge. To gain more insight into how and why the CATs influence outcomes, we conducted a scoping review (Nstudies = 67) to pinpoint therapeutic factors specific to each CATs discipline, joint factors of CATs, and more generic common factors across all psychotherapy approaches. This review therefore provides an overview of empirical CATs studies dealing with therapeutic factors and/or mechanisms of change, and a detailed analysis of these therapeutic factors which are grouped into domains. A framework of 19 domains of CATs therapeutic factors is proposed, of which the three domains are composed solely of factors unique to the CATs: “embodiment,” “concretization,” and “symbolism and metaphors.” The terminology used in change process research is clarified, and the implications for future research, clinical practice, and CATs education are discussed