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Local Solutions (local + solution)

Distribution by Scientific Domains

Mathematics and Statistics	33%
Business, Economics, Finance and Accounting	33%

Selected Abstracts

Local solutions to a model of piezoelectric materials

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 14 2004
Kamel Hamdache
Abstract A local existence theorem is proved for a non-linear coupled system modelling the electromechanical motion of a one-dimensional piezoelectric body with domain switching. The system is composed by a heat equation describing the behaviour of the number of electric dipoles and by a wave equation governing the dynamic of the electric displacement. The main coupling in the system appears in the time-dependent velocity of the waves depending on the number of electric dipoles. The proof of the result relies on a time decay estimate satisfied by the number of electric dipoles and an uniform estimate of the solution of the regularized wave equation. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Constrained tomography of realistic velocity models in microseismic monitoring using calibration shots

GEOPHYSICAL PROSPECTING, Issue 5 2010
T. Bardainne
ABSTRACT The knowledge of the velocity model in microseismic jobs is critical to achieving statistically reliable microseismic event locations. The design of microseismic networks and the limited sources for calibration do not allow for a full tomographic inversion. We propose optimizing a priori velocity models using a few active shots and a non-linear inversion, suitable to poorly constrained systems. The considered models can be described by several layers with different P- and S-wave velocities. The velocities may be constant or have 3D gradients; the layer interfaces may be simple dipping planes or more complex 3D surfaces. In this process the P- and S- wave arrival times and polarizations measured on the seismograms constitute the observed data set. They are used to estimate two misfit functions: i) one based on the measurement residuals and ii) one based on the inaccuracy of the source relocation. These two functions are minimized thanks to a simulated annealing scheme, which decreases the risk of converging to a local solution within the velocity model. The case study used to illustrate this methodology highlights the ability of this technique to constrain a velocity model with dipping layers. This was performed by jointly using sixteen perforation shots recorded during a multi-stage fracturing operation from a single string of 3C-receivers. This decreased the location inaccuracies and the residuals by a factor of six. In addition, the retrieved layer dip was consistent with the pseudo-horizontal trajectories of the wells and the background information provided by the customer. Finally, the theoretical position of each calibration shot was contained in the uncertainty domain of the relocation of each shot. In contrast, single-stage inversions provided different velocity models that were neither consistent between each other nor with the well trajectories. This example showed that it is essential to perform a multi-stage inversion to derive a better updated velocity model. [source]

Benchmarking as a Tool for the Modernisation of Local Government

FINANCIAL ACCOUNTABILITY & MANAGEMENT, Issue 4 2001
Mary Bowerman
This paper examines benchmarking as a tool of the modernisation process in local government and the contradictory tensions in the Best Value scheme are explored. Benchmarking is shown to encapsulate the dichotomous nature of a modernising philosophy which espouses innovation and local solutions alongside the government's centralising tendencies. One consequence is the advancement of ,compulsory' and ,defensive' modes of benchmarking with local authorities benchmarking for external accountability reasons; issues of tangible improvement are secondary concerns. These tensions are viewed as irreconcilable, the implication is that local government will need to carefully manage and evaluate its benchmarking activities. [source]

Globalization vs. localization: global food challenges and local solutions

INTERNATIONAL JOURNAL OF CONSUMER STUDIES, Issue 3 2010
Quaye Wilhelmina
Abstract The objective of this study was to examine the effect of global,local interactions on food production and consumption in Ghana, and identify possible local solutions. Primary data were collected using a combination of quantitative-qualitative methods, which included focus group discussions and one-on-one interviews. Approximately 450 household heads were randomly selected and interviewed between August 2007 and August 2008 in Eastern, Central, Upper East and Northern Regions of Ghana. Findings revealed increasing consumption of foreign rice as opposed to decreasing consumption of local rice and other staples like millet, sorghum and yam because of global,local interactions. However, opportunities exist to re-localize production-consumption patterns through the use of ,glocal foods' like improved ,koose and waakye'. Referencing the situation in Ghana, the study recommends improved production and processing practices backed with appropriate technologies that reflect changing consumption dynamics in order to take full advantage of opportunities created as a result of global,local interactions. [source]

A centroid-based sampling strategy for kriging global modeling and optimization

AICHE JOURNAL, Issue 1 2010
Eddie Davis
Abstract A new sampling strategy is presented for kriging-based global modeling. The strategy is used within a kriging/response surface (RSM) algorithm for solving NLP containing black-box models. Black-box models describe systems lacking the closed-form equations necessary for conventional gradient-based optimization. System optima can be alternatively found by building iteratively updated kriging models, and then refining local solutions using RSM. The application of the new sampling strategy results in accurate global model generation at lower sampling expense relative to a strategy using randomized and heuristic-based sampling for initial and subsequent model construction, respectively. The new strategy relies on construction of an initial kriging model built using sampling data obtained at the feasible region's convex polytope vertices and centroid. Updated models are constructed using additional sampling information obtained at Delaunay triangulation centroids. The new sampling algorithm is applied within the kriging-RSM framework to several numerical examples and case studies to demonstrate proof of concept. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

Global well-posedness of the Cauchy problem for certain magnetohydrodynamic-, models

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 13 2010
Yi Du
Abstract This paper is devoted to study the Cauchy problem for certain incompressible magnetohydrodynamics-, model. In the Sobolev space with fractional index s>1, we proved the local solutions for any initial data, and global solutions for small initial data. Furthermore, we also prove that as ,,0, the MHD-, model reduces to the MHD equations, and the solutions of the MHD-, model converge to a pair of solutions for the MHD equations. Copyright © 2010 John Wiley & Sons, Ltd. [source]

The Politics of Obesity: A Current Assessment and Look Ahead

THE MILBANK QUARTERLY, Issue 1 2009
ROGAN KERSH
Context: The continuing rise in obesity rates across the United States has proved impervious to clinical treatment or public health exhortation, necessitating policy responses. Nearly a decade's worth of political debates may be hardening into an obesity issue regime, comprising established sets of cognitive frames, stakeholders, and policy options. Methods: This article is a survey of reports on recently published studies. Findings: Much of the political discussion regarding obesity is centered on two "frames," personal-responsibility and environmental, yielding very different sets of policy responses. While policy efforts at the federal level have resulted in little action to date, state and/or local solutions such as calorie menu labeling and the expansion of regulations to reduce unhealthy foods at school may have more impact. Conclusions: Obesity politics is evolving toward a relatively stable state of equilibrium, which could make comprehensive reforms to limit rising obesity rates less feasible. Therefore, to achieve meaningful change, rapid-response research identifying a set of promising reforms, combined with concerted lobbying action, will be necessary. [source]

On the initial-boundary value problem of the incompressible viscoelastic fluid system

COMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 4 2008
Fanghua Lin
In this paper, we shall establish the local well-posedness of the initial-boundary value problem of the viscoelastic fluid system of the Oldroyd model. We shall also prove that the local solutions can be extended globally and that the global solutions decay exponentially fast as time goes to infinity provided that the initial data are sufficiently close to the equilibrium state. © 2007 Wiley Periodicals, Inc. [source]