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Weighting Coefficients (weighting + coefficient)

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Engineering100%

Selected Abstracts

Streamflow estimation using optimal regional dependency function

HYDROLOGICAL PROCESSES, Issue 25 2009
Abdüsselam Altunkaynak
Abstract The determination of spatial dependency of regionalized variable (ReV) is important in engineering studies. Regional dependency function that leads to calculation of weighting coefficients is required in order to make regional or point-wise estimations. After obtaining this dependency function, it is possible to complete missing records in the time series and locate new measurement station. Also determination of regional dependency function is also useful to understand the regional variation of ReV. Point Cumulative Semi-Variogram (PCSV) is another methodology to understand the regional dependency of ReV related to the magnitude and the location. However, this methodology is not useful to determine the weighting coefficient, which is required to make regional and point-wise estimations. However, in Point Semi-Variogram (PSV) proposed here, weighting coefficient depends on both magnitude and location. Although the regional dependency function has a fluctuating structure in PSV approach, this function gradually increases with distance in PCSV. The study area is selected in Mississippi river basin with 38 streamflow stations used for PCSV application before. It is aimed to compare two different geostatistical models for the same data set. PSV method has an ability to determine the value of variable along with optimum number of neighbour stations and influence radius. PSV and slope PSV approaches are compared with the PCSV. It was shown that slope slope point semi-variogram (SPSV) approaches had relative error below 5%, and PSV and PCSV methods revealed relative errors below 10%. Copyright © 2009 John Wiley & Sons, Ltd. [source]

An interpolation-based local differential quadrature method to solve partial differential equations using irregularly distributed nodes

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 7 2008
Hang Ma
Abstract To circumvent the constraint in application of the conventional differential quadrature (DQ) method that the solution domain has to be a regular region, an interpolation-based local differential quadrature (LDQ) method is proposed in this paper. Instead of using regular nodes placed on mesh lines in the DQ method (DQM), irregularly distributed nodes are employed in the LDQ method. That is, any spatial derivative at a nodal point is approximated by a linear weighted sum of the functional values of irregularly distributed nodes in the local physical domain. The feature of the new approach lies in the fact that the weighting coefficients are determined by the quadrature rule over the irregularly distributed local supporting nodes with the aid of nodal interpolation techniques developed in the paper. Because of this distinctive feature, the LDQ method can be consistently applied to linear and nonlinear problems and is really a mesh-free method without the limitation in the solution domain of the conventional DQM. The effectiveness and efficiency of the method are validated by two simple numerical examples by solving boundary-value problems of a linear and a nonlinear partial differential equation. Copyright © 2007 John Wiley & Sons, Ltd. [source]

A robust surface-integral-equation formulation for conductive media

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2005
Yun-Hui Chu
Abstract A novel surface-integral-equation (SIE) formulation is proposed by tuning the weighting coefficients for the external- and internal-region integral equations. Without increasing the computational cost, the present formulation significantly enlarges the solvable skin-depth range. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 109,114, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20916 [source]

An efficient scheme for minimax solutions of multiple linear-quadratic control

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 6 2005
Wan-Lung Ng
Abstract Optimal control is one of the most important methodologies for studies of dynamic systems in many areas of sciences, engineering and economics. Minimax optimal control is a special topic in the general framework of multiple optimal control problems. Minimax optimal control can be considered as a dynamic game with multiple players under the same system. In this paper, we develop a fast search for a minimax solution of multiple linear-quadratic control problems. The algorithm improves the existing solution scheme by adjusting the multiple weighting coefficients in each iteration and also including updates for step-size control. Copyright © 2005 John Wiley & Sons, Ltd. [source]