352 research outputs found
O método de Newton inexato aplicado às equações de Navier-Stokes: Hilbeth Parente de Deus ; orientador, Mário César Zambaldi
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Matemática e Computação CientíficaO trabalho aqui presente destina-se a fazer uma análise comparativa, no contexo do método de Newton inexato, os desempenhos das metodologias iterativas baseadas em subespaços de Krylov: GMRES (Generalized Minimum Residual Method) e Bi-CGStab (Biconjugate Gradient Stabilized) e um método direto (LU esparso). As características das desempenhos (número de iterações e tempo computacional) das metodologias investigadas são acessadas com o uso de alguns testes padrão largamente utilizados como "benchmark" em mecânica dos fluidos computacional. O método de Newton inexato baseado em GMRES e Bi-CGStab é aplicado no sistema não linear gerado pelo método de elementos finitos (MEF) sobre o problema de valor de contorno composto pelas equações de Navier-Stokes. Uma importante observação diz respeito a condição necessária e suficiente de Brezzi-Babuka (ou condições inf-sup), a qual é satisfeita com o uso de parâmetros de estabilização
ELABORACIÓN DE CRITERIOS E INDICADORES PARA DESARROLLAR Y EVALUAR PROGRAMAS DE ENVEJECIMIENTO SALUDABLE EN LOS LUGARES DE TRABAJO
No full textFundamentos:En el actual contexto poblacional de envejecimiento dela población y prolongación de la vida laboral, los programas de promociónde salud en el trabajo son una herramienta clave y necesaria para promoverun envejecimiento activo y saludable. El objetivo fue elaborar una herra-mienta tipo lista de verificación para orientar la planificación, implemen-tación y evaluación de buenas prácticas en intervenciones en este ámbito,aplicables a una variedad de programas, países y centros de trabajo.Métodos:Se utilizó una técnica Delphi en tres rondas en la que parti-ciparon expertos/as de cinco países europeos. Se elaboró un cuestionario enlínea a partir de una lista de criterios e indicadores y, empleando el correoelectrónico, se trabajó durante las sucesivas rondas en su adaptación a laevaluación de intervenciones. Mediante procesos de valoración y consenso,se priorizaron los criterios e indicadores más relevantes.Resultados:Partiendo de nueve criterios basales se priorizaron cuatrocriterios clave cuyas puntuaciones medias fueron: relevancia: 62, adecua-ción al objetivo: 57, innovación: 50 y garantía de calidad: 41. Utilizandoesta matriz de criterios e indicadores se diseñó una lista de verificación conla información clave que debe recogerse a la hora de planificar, implementary evaluar buenas prácticas en las intervenciones.Conclusiones:La lista de verificación ayuda a sistematizar la metodo-logía global de implantación de intervenciones que puede ser utilizada porresponsables de los programas para promover el envejecimiento activo ysaludable en los centros de trabajo
SUSY Dark Matter searches at ATLAS
No full textSupersymmetry provides an excellent dark matter candidate. SUSY searches at ATLAS cover an extensive range of scenarios with either a neutralino or a gravitino LSP. I give an overview of the ATLAS SUSY searches, with emphasis on the latest public results
Search for supersymmetry in events with four or more leptons and missing transverse momentum in p-p collisions at sqrt(s)=7 TeV with the ATLAS detector
No full textA search for supersymmetric particles in final states with four or more leptons is presented. The analysis uses 2.06 fb-1 of 7 TeV proton-proton collision data delivered by the LHC and recorded by the ATLAS detector in 2011. No significant excess above expectations from Standard Model is found. Constrains are set to an R-parity violating mSUGRA/CMSSM model. These are the first limits from the LHC experiments on a model with a stau as the lightest supersymmetric particle
Measurement of the production cross section for Z/gamma* in association with jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS Detector
No full textThe study of the production of jets of particles in association with a Z/gamma* boson in proton-proton collisions at sqrt(s) = 7 TeV provides a stringent test of perturbative quantum chromodynamics (pQCD). The proper understanding of events containing QCD jets in association with a Z/gamma* boson in the Standard Model (SM) is a fundamental element of the LHC physics program of searches for new physics, for which events with such final states constitute irreducible backgrounds. These SM background contributions are estimated using Monte Carlo (MC) predictions that include leading-order (LO) matrix elements supplemented by parton showers, which a priori are affected by large scale uncertainties and need to be tuned and validated using data. We present measurements of inclusive jet cross sections in Z/gamma* events, with Z/gamma* decaying into electron or muon pairs, as a function of jet transverse momentum and jet multiplicity, using 33 pb−1 of data collected by the ATLAS experiment in 2010. The measurements are compared to next-to-leading-order pQCD calculations, and to predictions from different MC generators implementing LO matrix elements supplemented by parton showers
Studies of vector boson + jet production with ATLAS
No full textThe production of jets in association with a W or Z boson in proton-proton collisions at 7 TeV is an important process to understand in QCD. The cross section, differential in several kinematics variables, has been measured up to high jet multiplicities and compared to new higher-order QCD calculations. The ratio of (Z + a single jet)/(W + a single jet) can provide a very precise test of QCD and has also been measured. In addition, the cross sections for vector bosons produced with bottom jets, Z+b-jet and W+b-jet, have been measured and compared to NLO QCD calculations. Overall, the cross sections demonstrate the need for the inclusion of higher-multiplicity matrix elements in the calculations, even in cases where a parton shower simulation is present
Um procedimento para a otimização de forma aplicado a escoamento de fluidos
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Mecânica.O trabalho aqui presente destina-se a fazer uma abordagem de um problema de Otimização de Forma, via Método de Elementos Finitos de Galerkin, sendo os alvos de estudos as equações de Navier-Stokes e Continuidade (bidimensionais). Os escoamentos aqui tratados são incompressíveis e encontram-se em regime permanente. O objetivo do trabalho é dado um escoamento sobre uma superfície, encontrar a forma desta que "minimiza" a dissipação viscosa do escoamento analisado. Sendo esta definida como a função objetivo do nosso problema de ótimo, e onde as restrições encontradas são do tipo lateral e/ou volumétrica. O tratamento dado neste trabalho ao problema de otimização de forma é fortemente baseado no cálculo do gradiente da função objetivo, que é feito numericamente. Este cálculo se dá através de diferença finita central, onde cada uma das variáveis de projeto são "perturbadas" em ambas as direções. A cada perturbação dada uma nova malha é gerada para o domínio e a análise do escoamento é refeita. A formulação implementada para a análise do escoamento, possui ainda parâmetros de estabilização que possibilitam o tratamento de escoamentos em que valores elevados do número de Reynolds (Re ~ 1000) estejam envolvidos, bem como permitem a não satisfação das condições de Brezzi-Babuska (ou condições de inf-sup). A eficiência desta estratégia é checada em duas aplicações. O critério de otimalidade adotado é a satisfação das condições de Kuhn-Tucke
Correction: Feasibility and acceptability of implementing the Global Scales for Early Development (GSED) package for children 0–3 years across three countries
No full textFollowing publication of the original article [1], the authors reported an error in the author names of Magdalena Janus, Yvonne Schönbeck, Abdullah H. Baqui and Rasheda Khanam, and an error to the affiliations of authors Tarun Dua, Romuald Kouadio E. Anago, Michelle Perez Maillard and Gillian Lancaster. The incorrect author name is: Magdalana Janus. The correct author name is: Magdalena Janus. The incorrect author name is: Yvonne Schonbeck. The correct author name is: Yvonne Schönbeck. The incorrect author name is: Abdullah Baqui. The correct author name is: Abdullah H. Baqui. The incorrect author name is: Rasheda Khanum. The correct author name is: Rasheda Khanam. Authors Tarun Dua and Michelle Perez Maillard should be affiliated to “Department of Mental Health and Substance Use, World Health Organization, Geneva, Switzerland”, author Romuald Kouadio E. Anago should be affiliated to “Innovations for Poverty Action, IPA Côte d’Ivoire, Abidjan, Côte d’Ivoire”, and author Gillian Lancaster should be affiliated to “School of Medicine, Keele University, Keele, UK”. The author group has been updated above and the original article [1] has been corrected
Timepix3 performance in power pulsing operation
No full textThe physics aims at the proposed CLIC linear collider impose challenging requirements on the performance of the detector system. In particular for the vertex detector the principal challenge is building an ultra-low mass (0.2% X per layer) detector that can provide a single point resolution of a few micrometers as well as 10ns time slicing capabilities. To reach such low material budget, CLIC uses an air-flow cooling system in the inner vertex region. This requires very low power dissipation, which is achieved by exploiting CLIC’s low duty cycle (0.001%) and beam structure, allowing pulsed power operation of the pixel detector. Timepix3 includes power pulsing features, such as, in the analog domain, allowing to switch dynamically between nominal power and shutdown modes, and, in the digital domain, gating the clock of the pixel matrix. This contribution reports the performance of the Timepix3 chip in pulsed power operation, in terms of power saving, detection efficiency and noise performance. Measurements were performed in beam tests taking as reference tracks provided by a telescope, as well as in the laboratory using a radioactive source
First measurement of the Z+jets production cross section with the ATLAS experiment at the LHC
No full textThe measurement of the inclusive jet production cross section in association with a Z boson is one of the most important Standard Model measurements at the Large Hadron Collider (LHC). It constitutes a stringent test of perturbative Quantum ChromoDynamics (pQCD) and is sensitive to new particles decaying into Z+jets final states. Moreover, the process represents an important background for new physics searches. This document reports a first measurement of the inclusive Z+jets production cross section with the ATLAS detector in sqrt(s) = 7 TeV proton-proton collisions. The measurement is performed in the Z(->e+e-) channel with 33 1/pb of integrated luminosity collected by ATLAS in 2010. The electron and muon channel measurements are compared, and the combination of both results is performed. The cross section is measured as a function of the jet multiplicity, the kinematic properties of the jet, and the invariant mass and spatial separation between the two leading jets. The measured cross sections are compared to the pQCD Next-to-Leading Order (NLO) predictions by MCFM and BlackHat, which include non-perturbative corrections. Comparisons to Leading Order (LO) predictions supplemented by parton shower (as implemented in ALPGEN and Sherpa Monte Carlo generators) are also performed, where the predictions are normalized to the inclusive Next-to-Next-to-Leading Order (NNLO) predictions. The predictions from PYTHIA LO predictions supplemented by parton shower and normalized to the measured cross section in the 1 jet inclusive bin are considered as well. The measured cross sections are well described by NLO pQCD predictions as well as by ALPGEN and Sherpa, while PYTHIA underestimates the cross section for high jet multiplicities
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