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Rapid Convergence (rapid + convergence)

Distribution by Scientific Domains
Mathematics and Statistics33%
Humanities and Social Sciences22%
Chemistry22%

Selected Abstracts

Elastic and inelastic drift performance optimization for reinforced concrete buildings under earthquake loads

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2004
Chun-Man Chan
Abstract This paper presents an effective optimization technique for the elastic and inelastic drift performance design of reinforced concrete buildings under response spectrum loading and pushover loading. Attempts have been made to develop an automatic optimal elastic and inelastic drift design of concrete framework structures. The entire optimization procedure can be divided into elastic design optimization and inelastic design optimization. Using the principle of virtual work, the elastic drift response generated by the response spectrum loading and the inelastic drift response produced by the non-linear pushover loading can be explicitly expressed in terms of element sizing design variables. The optimization methodology for the solution of the explicit design problem of buildings is fundamentally based on the Optimality Criteria approach. One ten-story, two-bay building frame example is presented to illustrate the effectiveness and practicality of the proposed optimal design method. While rapid convergence in a few design cycles is found in the elastic optimization process, relatively slow but steady and smooth convergence of the optimal performance-based design is found in the inelastic optimization process. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Relaxation of quantum hydrodynamic modes

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2002
Eric R. Bittner
Abstract In this article, we develop a series of hierarchical mode-coupling equations for the momentum cumulants and moments of the density matrix for a mixed quantum system. Working in the Lagrange representation, we show how these can be used to compute quantum trajectories for dissipative and nondissipative systems. This approach is complementary to the de Broglie,Bohm approach in that the moments evolve along hydrodynamic/Lagrangian paths. In the limit of no dissipation, the paths are the Bohmian paths. However, the "quantum force" in our case is represented in terms of momentum fluctuations and an osmotic pressure. Representative calculations for the relaxation of a harmonic system are presented to illustrate the rapid convergence of the cumulant expansion in the presence of a dissipative environment. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 [source]

Mind the Gaps: The Evolution of Regional Earnings Inequalities in the U.K., 1982,1997

JOURNAL OF REGIONAL SCIENCE, Issue 2 2002
Gilles Duranton
In this paper we apply earnings equations for U.K. regions over 1982,1997. We find evidence of rapid convergence across regions regarding the determinants of individual wages (i.e., regional fixed-effects, gender gaps, and returns to education and experience). In contrast, data on average regional earnings point to a worsening of U.K. regional inequalities and a rise in the North-South gap. Education accounts for most of the discrepancy between aggregate divergence and disaggregated convergence. First, London gained because its workforce became relatively more educated over the period. Second, returns to education increased nationwide, which favored the most educated regions (i.e., London). Third, returns to education were initially lower in London but they (partially) caught up with the rest of the country. Had returns to education and their distribution across U.K. regions remained stable over the period, the U.K. North-South divide would have decreased. [source]

The absolute center of a network,

NETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2004
Dov Dvir
Abstract This paper presents a new algorithm for finding an absolute center (minimax criterion) of an undirected network with n nodes and m arcs based on the concept of minimum-diameter trees. Local centers and their associated radii are identified by a monotonically increasing sequence of lower bounds on the radii. Computational efficiency is addressed in terms of worst-case complexity and practical performance. The complexity of the algorithm is 0(n2 ,g n + mn). In practice, because of its very rapid convergence, the algorithm renders the problem amenable even to manual solution for quite large networks, provided that the minimal-distance matrix is given. Otherwise, evaluation of this matrix is the effective computational bottleneck. An interesting feature of the algorithm and its theoretical foundations is that it synthesizes and generalizes some well-known results in this area, particularly Halpern's lower bound on the local radius of a network and properties of centers of tree networks. © 2004 Wiley Periodicals, Inc. [source]

Krylov subspaces and the analytic grade

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 1 2005
M. Ili
Abstract Typical behaviour of the solution of a linear system of equations obtained iteratively by Krylov methods can be characterized by three stages. Initially the residual diminishes steadily; this is followed by stagnation and finally rapid convergence near the algebraic grade. This study examines this behaviour in terms of the concepts of approximately invariant subspace and what we have called the analytic grade of a Krylov sequence. It is shown how the small Ritz values play a vital role in the convergence and how this knowledge helps in the construction of an effective preconditioner. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Analysis of a block red-black preconditioner applied to the Hermite collocation discretization of a model parabolic equation

NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 6 2001
Stephen H. Brill
Abstract We are concerned with the numerical solution of a model parabolic partial differential equation (PDE) in two spatial dimensions, discretized by Hermite collocation. In order to efficiently solve the resulting systems of linear algebraic equations, we choose the Bi-CGSTAB method of van der Vorst (1992) with block Red-Black Gauss-Seidel (RBGS) preconditioner. In this article, we give analytic formulae for the eigenvalues that control the rate at which Bi-CGSTAB/RBGS converges. These formulae, which depend on the location of the collocation points, can be utilized to determine where the collocation points should be placed in order to make the Bi-CGSTAB/RBGS method converge as quickly as possible. Along these lines, we discuss issues of choice of time-step size in the context of rapid convergence. A complete stability analysis is also included. © 2001 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 17:584,606, 2001 [source]

Further developments in the new approach to boundary condition iteration in optimal control

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2001
Rein LuusArticle first published online: 3 SEP 2010
Abstract In solving the boundary value problem resulting from the use of Pontryagin's maximum principle, a transformation matrix is used to relate the sensitivity of the final state to the initial state. This avoids the need to solve the (n × n) differential equation to give the transition matrix, and yields very rapid convergence to the optimum. To ensure convergence, iterative dynamic programming (IDP) is used for a number of passes to yield good starting conditions for this boundary condition iteration procedure. Clipping technique is used to handle constraints on control. Five optimal control problems are used to illustrate and to test the procedure. Dans la résolution du problème de valeur limlte résultant de l'utilisation du principe maximum de Pontryagin, on utilise une matrice de transformation afin de relier la sensibilité de l'état final à l'état initial. Cela évite d'avoir à résoudre l'équation différentielle (n × n) pour obtenir la matrice de transition et permet une convergence trés rapide vers l'optimum. Pour assurer la convergence, on a recours à la programmation dynamique itérative (IDP) pour plusieurs passages afin de créer de bonnes conditions de démarrage pour cette méthode d'itération sur les conditions limites. On utilise la technique de l'écêtage pour manier les contraintes sur le contrôle. Cinq problèmes de contrôle optimal permettent d'illustrer et de vérifier la méthode. [source]

PROSPECTS FOR ,CLOSING THE GAP' IN SOCIOECONOMIC OUTCOMES FOR INDIGENOUS AUSTRALIANS?

AUSTRALIAN ECONOMIC HISTORY REVIEW, Issue 3 2009
Jon C. Altman
Australia; aborigines; closing the gap; long-run social and economic change; Torres Strait islanders Practical reconciliation' and more recently ,closing the gap' have been put forward as frameworks on which to base and evaluate policies to address Indigenous disadvantage. This paper analyses national-level census-based data to examine trends in Indigenous wellbeing since 1971. There has been steady improvement in most socioeconomic outcomes in the last 35 years; a finding at odds with the current discourse of failure. Evidence of convergence between Indigenous and non-Indigenous outcomes, however, is not consistent. For some outcomes, relatively rapid convergence is predicted (within 25 years), but for the majority of outcomes, convergence is unlikely to occur within a generation, if at all. [source]

Money Demand in an EU Accession Country: A VECM Study of Croatia

BULLETIN OF ECONOMIC RESEARCH, Issue 2 2006
Dario Cziráky
O42; E13; E41; E51 Abstract The paper estimates the money demand in Croatia using monthly data from 1994 to 2002. A failure of the Fisher equation is found, and adjustment to the standard money-demand function is made to include the inflation rate as well as the nominal interest rate. In a two-equation cointegrated system, a stable money demand shows rapid convergence back to equilibrium after shocks. This function performs better than an alternative using the exchange rate instead of the inflation rate as in the ,pass-through' literature on exchange rates. The results provide a basis for inflation rate forecasting and suggest the ability to use inflation targeting goals in transition countries during the EU accession process. Finding a stable money demand also limits the scope for central bank ,inflation bias'. [source]