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Local Approach (local + approach)
Selected AbstractsCoupling of Forming Process and Fatigue Design Computations: A Local ApproachADVANCED ENGINEERING MATERIALS, Issue 9 2009Matteo Luca Facchinetti The fatigue design of stamped parts is supposed to take into account for the forming process. In this paper, stamping of steel sheets is addressed by basic rules coming from elementary solid mechanics and plasticity. As an effective alternative to complex FE computations, such a pragmatic approach highlights how the forming process affects fatigue design and allows direct application in an industrial framework. [source] A Comparison of Conventional Local Approach and the Short Crack Approach to Fatigue Crack Initiation at a Notch,ADVANCED ENGINEERING MATERIALS, Issue 9 2009Narayanaswami Ranganathan Methods to estimate fatigue crack initiation life at a notch tip are compared. The methods used determine the strain amplitudes at the notch tip using Neuber's or Glinka's approximation. In conventional approaches, equivalent-damage levels are determined, using appropriate strain-life relationships coupled with damage-summation models. In the short-crack approach, a crack-like defect is assumed to exist at the notch tip. It is shown that the short-crack concept can be successfully applied to predict crack-initiation behavior at a notch. Model predictions are compared with carefully designed experiments. It is shown that model predictions are very close to experimentally measured lives under an aircraft-wing loading spectrum. [source] Determining the life cycle of bolts using a local approach and the Dang Van criterionFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 8 2006Y. FARES ABSTRACT The fatigue behaviour of bolts under axial load has always been considered from the component point of view for which fatigue limit is usually taken equal to 50 MPa, and few results are available to designers for limited lifetimes. Here, we take up this problem from a material point of view using a local approach. For each case of fatigue testing, using finite-element (FE) model of the bolt, we determine the stabilized local stress at the root of the first thread in contact with the nut. To characterize bolt behaviour with these numerical results, we use Dang Van multiaxial fatigue criterion for which we extend application to the medium fatigue life. These results can be correlated with the experimental numbers of cycles to failure to determine material parameters of the generalized criterion. Using statistical Gauss method, we can make lifetime predictions for any level of risk of failure. In addition, we propose an analytical model to rapidly determine the local stress condition from nominal loading data (mean stress and alternating stress). This model dispenses us from a new modelling if the bolt is stressed in the same manner as the bolts used for behaviour characterization. Using this model and the generalized criterion, it is extremely easy to make lifetime predictions whatever the risk considered. [source] Void growth and damage models for predicting ductile fracture in weldsFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 2 2000Wilsius This study reports on a numerical and experimental investigation of ductile tearing using a local approach to fracture. Two models have been analysed: (i) the Rice,Tracey (RT) void growth model; and (ii) the Rousselier continuum damage theory. The effects of the model parameters, including the mesh size, on the crack growth behaviour have been analysed, and a significant influence on both the J -values and the slopes dJ/da has been noted. The crack propagation in an overmatched welded joint has also been investigated. For the RT model, crack propagation has been simulated using the release node technique. Because this method requires one to previously assign the crack propagation path, using such a model is somewhat restrictive. This problem vanishes when dealing with Rousselier's model (and more generally with coupled models) because the elements which are damaged automatically give the crack path. [source] Measuring and managing engagement in a cross-cultural workforce: New insights for global companiesGLOBAL BUSINESS AND ORGANIZATIONAL EXCELLENCE, Issue 1 2006Paul Sanchez Should a company take a global or local approach to building engagement in its worldwide workforce? Research by Mercer Human Resource Consulting finds that country norms for drivers of engagement, as well as for other employee perceptions about their work and their employers, differ noticeably from region to region,and not in ways that might be expected. But a core set of drivers is emerging globally. This should help multinational companies distinguish between global and local engagement issues, design a manageable global engagement strategy and initiatives, and tailor implementation to meet the needs and preferences of the local workforce. © 2006 Wiley Periodicals, Inc. [source] Non-local dispersive model for wave propagation in heterogeneous media: multi-dimensional caseINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2002Jacob Fish Abstract Three non-dispersive models in multi-dimensions have been developed. The first model consists of a leading-order homogenized equation of motion subjected to the secularity constraints imposing uniform validity of asymptotic expansions. The second, non-local model, contains a fourth-order spatial derivative and thus requires C1 continuous finite element formulation. The third model, which is limited to the constant mass density and a macroscopically orthotropic heterogeneous medium, requires C0 continuity only and its finite element formulation is almost identical to the classical local approach with the exception of the mass matrix. The modified mass matrix consists of the classical mass matrix (lumped or consistent) perturbed with a stiffness matrix whose constitutive matrix depends on the unit cell solution. Numerical results are presented to validate the present formulations. Copyright © 2002 John Wiley & Sons, Ltd. [source] On the quadrilateral Q2,P1 element for the Stokes problemINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2002Daniele Boffi Abstract The Q2 , P1 approximation is one of the most popular Stokes elements. Two possible choices are given for the definition of the pressure space: one can either use a global pressure approximation (that is on each quadrilateral the finite element space is spanned by 1 and by the global co-ordinates x and y) or a local approach (consisting in generating the local space by means of the constants and the local curvilinear co-ordinates on each quadrilateral , and ,). The former choice is known to provide optimal error estimates on general meshes. This has been shown, as it is standard, by proving a discrete inf,sup condition. In the present paper we check that the latter approach satisfies the inf,sup condition as well. However, recent results on quadrilateral finite elements bring to light a lack in the approximation properties for the space coming out from the local pressure approach. Numerical results actually show that the second choice (local or mapped pressure approximation) is suboptimally convergent. Copyright © 2002 John Wiley & Sons, Ltd. [source] A simple and linear time randomized algorithm for computing sparse spanners in weighted graphs,RANDOM STRUCTURES AND ALGORITHMS, Issue 4 2007Surender Baswana Abstract Let G = (V,E) be an undirected weighted graph on |V | = n vertices and |E| = m edges. A t -spanner of the graph G, for any t , 1, is a subgraph (V,ES), ES , E, such that the distance between any pair of vertices in the subgraph is at most t times the distance between them in the graph G. Computing a t -spanner of minimum size (number of edges) has been a widely studied and well-motivated problem in computer science. In this paper we present the first linear time randomized algorithm that computes a t -spanner of a given weighted graph. Moreover, the size of the t -spanner computed essentially matches the worst case lower bound implied by a 43-year old girth lower bound conjecture made independently by Erd,s, Bollobás, and Bondy & Simonovits. Our algorithm uses a novel clustering approach that avoids any distance computation altogether. This feature is somewhat surprising since all the previously existing algorithms employ computation of some sort of local or global distance information, which involves growing either breadth first search trees up to ,(t)-levels or full shortest path trees on a large fraction of vertices. The truly local approach of our algorithm also leads to equally simple and efficient algorithms for computing spanners in other important computational environments like distributed, parallel, and external memory. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007 [source] All linear methods are equal,and extendible to (some) nonlinearitiesINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2002Janos GertlerArticle first published online: 17 JUN 200 Abstract Several linear methods of residual generation for fault detection and diagnosis are reviewed. The parity relation approach is introduced in some detail, for both additive and parametric faults. The Chow,Willsky scheme, various diagnostic observers and principal component analysis are compared to the additive version. The ,local approach' and the least-squares estimation of parameter changes are shown to be related to the parametric variant. Nonlinear extensions are demonstrated for all the techniques under additive faults. Copyright © 2002 John Wiley & Sons, Ltd. [source] Sensitivity Analyses of Spatial Population Viability Analysis Models for Species at Risk and Habitat Conservation PlanningCONSERVATION BIOLOGY, Issue 1 2009ILONA R. NAUJOKAITIS-LEWIS análisis de sensibilidad; análisis de viabilidad poblacional; incertidumbre; metapoblación; planificación de la conservación Abstract:,Population viability analysis (PVA) is an effective framework for modeling species- and habitat-recovery efforts, but uncertainty in parameter estimates and model structure can lead to unreliable predictions. Integrating complex and often uncertain information into spatial PVA models requires that comprehensive sensitivity analyses be applied to explore the influence of spatial and nonspatial parameters on model predictions. We reviewed 87 analyses of spatial demographic PVA models of plants and animals to identify common approaches to sensitivity analysis in recent publications. In contrast to best practices recommended in the broader modeling community, sensitivity analyses of spatial PVAs were typically ad hoc, inconsistent, and difficult to compare. Most studies applied local approaches to sensitivity analyses, but few varied multiple parameters simultaneously. A lack of standards for sensitivity analysis and reporting in spatial PVAs has the potential to compromise the ability to learn collectively from PVA results, accurately interpret results in cases where model relationships include nonlinearities and interactions, prioritize monitoring and management actions, and ensure conservation-planning decisions are robust to uncertainties in spatial and nonspatial parameters. Our review underscores the need to develop tools for global sensitivity analysis and apply these to spatial PVA. Resumen:,El análisis de viabilidad poblacional (AVP) es un marco de referencia efectivo para los esfuerzos de recuperación de especie y de hábitat, pero la incertidumbre en las estimaciones de parámetros y la estructura del modelo pueden llevar a predicciones no confiables. La integración de información compleja y a menudo incierta a los modelos de AVP espaciales requiere la aplicación de análisis de sensibilidad para explorar la influencia de parámetros espaciales y no espaciales sobre las predicciones de los modelos. Revisamos 87 análisis de modelos de AVP demográficos espaciales de plantas y animales para identificar métodos comunes de análisis de sensibilidad en publicaciones recientes. En contraste con las mejores prácticas recomendadas por la comunidad de modeladores, los análisis de los sensibilidad de AVP típicamente fueron ad hoc, inconsistentes y difíciles de comparar. La mayoría de los estudios aplicaron métodos locales a los análisis de sensibilidad, pero pocos variaron parámetros múltiples simultáneamente. La falta de estándares para los análisis de sensibilidad y descripción en los AVP espaciales tiene el potencial de comprometer la habilidad de aprender colectivamente de los resultados de AVP, de interpretar con precisión los resultados en casos en que las relaciones de los modelos sean no lineales e incluyan interacciones, para priorizar las acciones de monitoreo y manejo y para asegurar que la planificación de las decisiones de conservación sean robustas ante la incertidumbre en los parámetros espaciales y no espaciales. Nuestra revisión subraya la necesidad de desarrollar herramientas para análisis de sensibilidad globales y aplicarlos a AVP espaciales. [source] Fatigue assessment of welded joints by local approaches, Second edition.MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 12 2006[source] There's Regulatory Crime, and then there's Landlord Crime: from ,Rachmanites' to ,Partners'THE MODERN LAW REVIEW, Issue 6 2001Dave Cowan This article considers local authority strategies towards the regulation and prosecution of private landlords who commit the criminal offences of unlawful eviction and harassment. Generally, local authorities operate compliance-based strategies, rarely (if ever) resorting to prosecution. In seeking to explain this approach, the article draws upon the literature concerning regulatory crime, but also distinguishes local authority responses to landlord crime from regulatory crime as more typically conceived. Broadly, it is argued that, while there are clear parallels with other areas of regulatory activity, there is much that is different about landlord crime, particularly as a result of central government strategies towards the private rented sector, the legislative background to landlord crime, and the motivations behind local approaches to regulation. [source] History of the Care of Displaced Children in KoreaASIAN SOCIAL WORK AND POLICY REVIEW, Issue 1 2008Jung-Woo Kim The present article explores the current nature and history of welfare provision for displaced children in Korea. It examines the early examples of care and the perspectives on the issue from scholars, lawmakers, religion and society as a whole. This provides an understanding of the background and, especially, the cultural roots of existing care. A history of what may be considered the first modern displaced child welfare provision is also given with analysis of how Christian and local approaches and perceptions integrated. This was to form the basis for present-day transitional displaced child welfare in Korea. For this reason, the article examines the provision in a paradigm which looks at the provision as responses to Western influences. Features of congregate care, domestic/international adoptions, foster care and youth-headed households are examined. The authors conclude that global forces will continue to be influential and recommends that religious institutions which have thus far provided crucial contributions to the foundation of care should continue to play key roles with the government's facilitation. The need for wide participation from society and coordination from the government to manage systems, develop strategies and build consensus is highlighted. [source] Maintaining a focus on the child?CHILD ABUSE REVIEW, Issue 4 2002First impressions of the Framework for the Assessment of Children in Need, their Families in cases of child neglect Abstract The Framework for the Assessment of Children in Need and their Families is guidance introduced by the Department of Health in England to improve assessment practice and promote better outcomes for children and their families. This paper considers ways in which the Assessment Framework can improve assessment practice in cases of child neglect. However, as with any national guidance, its effectiveness is dependent on local approaches to implementation. The author has undertaken practice development work around implementation with senior managers and frontline staff in area child protection committees (ACPCs) and social services departments. These experiences are used to explore the local issues and tensions encountered by both practitioners and managers responsible for implementing the Assessment Framework. An argument is made that these issues and tensions if not addressed can result in distorted assessments that lose the focus on the child. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||||||||