Global Convergence (global + convergence)

Distribution by Scientific Domains

Selected Abstracts

A modified modulus method for symmetric positive-definite linear complementarity problems

Jun-Liang Dong
Abstract By reformulating the linear complementarity problem into a new equivalent fixed-point equation, we deduce a modified modulus method, which is a generalization of the classical one. Convergence for this new method and the optima of the parameter involved are analyzed. Then, an inexact iteration process for this new method is presented, which adopts some kind of iterative methods for determining an approximate solution to each system of linear equations involved in the outer iteration. Global convergence for this inexact modulus method and two specific implementations for the inner iterations are discussed. Numerical results show that our new methods are more efficient than the classical one under suitable conditions. Copyright 2008 John Wiley & Sons, Ltd. [source]

Optimal Control of Iterative Solution Methods for Linear Systems of Equations

Uwe Helmke
Iterative solution methods for linear systems of equations can be regarded as discrete-time control systems, for which a stabilizing feedback control has to be found. Well known algorithms such as GMRES(m) may exhibit unstable dynamics or sensitive dependence on initial conditions, thus preventing the algorithm to converge to the desired solution. Based on linear system feedback design techniques a new algorithm is proposed that does not suffer under such shortcomings. Global convergence to the desired solution is shown for any initial state. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Creative Management: A Predicted Development from Research into Creativity and Management

Fangqi Xu
A proposal is made for the establishment of a conceptual domain of Creative Management by fusion of two related bodies of knowledge, that of management studies and creativity. Through an examination of examples from around the world, we show how Creative Management is appearing in embryonic form as a global possibility, emerging from and enriching the predominantly American contributions of earlier stages. We suggest that such a development will take management studies forward from its historical trajectory, through the global convergence of organizational theories and practices. The proposed synthesis of creativity and management indicates the possibilities of a new stage in management incorporating humanistic, socio-technical and knowledge management components. Collectively, the conceptual shift is towards what we have labelled Toyotaoism, in acknowledgement of practices and theorizing developed from the integration of Western and Eastern belief systems and theories in action. [source]

Migration velocity analysis and waveform inversion

William W. Symes
ABSTRACT Least-squares inversion of seismic reflection waveform data can reconstruct remarkably detailed models of subsurface structure and take into account essentially any physics of seismic wave propagation that can be modelled. However, the waveform inversion objective has many spurious local minima, hence convergence of descent methods (mandatory because of problem size) to useful Earth models requires accurate initial estimates of long-scale velocity structure. Migration velocity analysis, on the other hand, is capable of correcting substantially erroneous initial estimates of velocity at long scales. Migration velocity analysis is based on prestack depth migration, which is in turn based on linearized acoustic modelling (Born or single-scattering approximation). Two major variants of prestack depth migration, using binning of surface data and Claerbout's survey-sinking concept respectively, are in widespread use. Each type of prestack migration produces an image volume depending on redundant parameters and supplies a condition on the image volume, which expresses consistency between data and velocity model and is hence a basis for velocity analysis. The survey-sinking (depth-oriented) approach to prestack migration is less subject to kinematic artefacts than is the binning-based (surface-oriented) approach. Because kinematic artefacts strongly violate the consistency or semblance conditions, this observation suggests that velocity analysis based on depth-oriented prestack migration may be more appropriate in kinematically complex areas. Appropriate choice of objective (differential semblance) turns either form of migration velocity analysis into an optimization problem, for which Newton-like methods exhibit little tendency to stagnate at nonglobal minima. The extended modelling concept links migration velocity analysis to the apparently unrelated waveform inversion approach to estimation of Earth structure: from this point of view, migration velocity analysis is a solution method for the linearized waveform inversion problem. Extended modelling also provides a basis for a nonlinear generalization of migration velocity analysis. Preliminary numerical evidence suggests a new approach to nonlinear waveform inversion, which may combine the global convergence of velocity analysis with the physical fidelity of model-based data fitting. [source]

An unconditionally convergent algorithm for the evaluation of the ultimate limit state of RC sections subject to axial force and biaxial bending

G. Alfano
Abstract We present a numerical procedure, based upon a tangent approach, for evaluating the ultimate limit state (ULS) of reinforced concrete (RC) sections subject to axial force and biaxial bending. The RC sections are assumed to be of arbitrary polygonal shape and degree of connection; furthermore, it is possible to keep fixed a given amount of the total load and to find the ULS associated only with the remaining part which can be increased by means of a load multiplier. The solution procedure adopts two nested iterative schemes which, in turn, update the current value of the tentative ultimate load and the associated strain parameters. In this second scheme an effective integration procedure is used for evaluating in closed form, as explicit functions of the position vectors of the vertices of the section, the domain integrals appearing in the definition of the tangent matrix and of the stress resultants. Under mild hypotheses, which are practically satisfied for all cases of engineering interest, the existence and uniqueness of the ULS load multiplier is ensured and the global convergence of the proposed solution algorithm to such value is proved. An extensive set of numerical tests, carried out for rectangular, L-shaped and multicell sections shows the effectiveness of the proposed solution procedure. Copyright 2007 John Wiley & Sons, Ltd. [source]

Another step toward global convergence

Kang Cheng
The Financial Accounting Standards Board and the International Accounting Standards Board have worked together to develop a single set of accounting standards for business combinations. It will make things easier for corporate finance and accounting professionals when dealing with domestic versus international acquisitions. However, at first glance, the new FASB standard looks like a total revision of SFAS No. 141. What are the latest changes? 2008 Wiley Periodicals, Inc. [source]

Sustainable consumption and production: Trends, challenges and options for the Asia-Pacific region

Wei Zhao
Abstract This paper highlights current trends in consumption and production patterns in Asian developing countries and emerging economies. It describes the main challenges and opportunities for Asian countries making the transition towards sustainable consumption and production patterns. The main challenge for Asian economies is to address the unsustainable consumption patterns of urban consumers, which entails a policy shift from the current focus on pollution and inefficient industrial production. In view of future consumption trends and the global convergence of consumption patterns, the characteristics of the emerging ,global consumer class' are examined, with particular focus on urban ecological footprints and carbon emissions. Furthermore, the difference between urban and rural consumption is discussed, together with opportunities for low-carbon urban development in the megacities of Asian developing countries. To conclude, the paper presents an overview of current policy measures taken in Asian countries to green economic development and realise sustainable consumption and production patterns. [source]