Two optimization algorithms are presented that are capable of finding a global optimum in a computationally efficient manner: a gradient-based multistart algorithm based on Sobol sampling and a hybrid optimizer combin...
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Two optimization algorithms are presented that are capable of finding a global optimum in a computationally efficient manner: a gradient-based multistart algorithm based on Sobol sampling and a hybrid optimizer combining a genetic algorithm with a gradient-based algorithm. The optimizers are used to investigate multimodality in aerodynamic-shape-optimization problems. The performance of each algorithm is tested on an analytical test function as well as several aerodynamic-shape-optimization problems in two and three dimensions. In each problem the primary objectives are to classify the problem according to the degree of multimodality and to identify the preferred optimization algorithm for the problem. The results show that multimodality should not always be assumed in aerodynamic-shape-optimization problems. Typical two-dimensional airfoil-optimization problems are unimodal. Three-dimensional shape-optimization problems may contain local optima. The number of local optima tends to increase with increasing geometric degrees of freedom and design space bounds. For problems with a modest number of local optima, which we term somewhat multimodal, the gradient-based multistart Sobol algorithm is the most efficient method.
We present new algorithms for two problems on interval structures that arise in computer-aided manufacturing and in other areas. We give an O(Kn) time algorithm for the single-source K-link shortest path problem on an...
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We present new algorithms for two problems on interval structures that arise in computer-aided manufacturing and in other areas. We give an O(Kn) time algorithm for the single-source K-link shortest path problem on an interval graph with n weighted vertices, and two O(n) time algorithms for a generalized version of the optimal color-spanning problem for n points on a real line, where each point is assigned one of m colors (m <= n). A standard approach for solving the K-link shortest path problem would take O(Kn(2)) time, and thus our result offers a linear time improvement. The previously best known algorithm for the optimal color-spanning problem in R-1 takes O(n) time and space. We provide two algorithms for a generalized version of this problem in which each color must appear a specified minimum number of times. One of these two solutions is suitable for an online processing of the (streaming) input points;it uses O(m) working space for the ordinary one-dimensional optimal color-spanning problem. We also show several applications of our algorithms in computer-aided manufacturing and in other areas. (C) 2012 Elsevier B.V. All rights reserved.
For nonlinear differential-algebraic-equation subsystems, whose index is one and interconnection input is locally measurable, the problem of invertibility is discussed and the results are applied to the power systems ...
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For nonlinear differential-algebraic-equation subsystems, whose index is one and interconnection input is locally measurable, the problem of invertibility is discussed and the results are applied to the power systems component decentralized control. The inverse systems' definitions for such a class of differential-algebraic-equation subsystems are put forward. A recursive algorithm is proposed to judge whether the controlled systems are invertible. Then physically feasible. alpha-order integral right inverse systems are constructed, with which the composite systems are linearizaed and decoupled. Finally, decentralized excitation and valve coordinative control for one synchronous generator within multimachine power systems are studied and the simulation results based on MATLAB demonstrate the effectiveness of the control scheme proposed in this paper.
Within the framework of constrained density functional theory (CDFT), the diabatic or charge localized states of electron transfer (ET) have been constructed. Based on the diabatic states, inner reorganization energy ...
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Within the framework of constrained density functional theory (CDFT), the diabatic or charge localized states of electron transfer (ET) have been constructed. Based on the diabatic states, inner reorganization energy lambda(in) has been directly calculated. For solvent reorganization energy lambda(s), a novel and reasonable nonequilibrium solvation model is established by introducing a constrained equilibrium manipulation, and a new expression of lambda(s) has been formulated. It is found that lambda(s) is actually the cost of maintaining the residual polarization, which equilibrates with the extra electric field. On the basis of diabatic states constructed by CDFT, a numerical algorithm using the new formulations with the dielectric polarizable continuum model (D-PCM) has been implemented. As typical test cases, self-exchange ET reactions between tetracyanoethylene (TCNE) and tetrathiafulvalene (TTF) and their corresponding ionic radicals in acetonitrile are investigated. The calculated reorganization energies A are 7293 cm(-1) for TCNE/TCNE- and 5939 cm(-1) for TTF/TTF+ reactions, agreeing well with available experimental results of 7250 cm(-1) and 5810 cm(-1), respectively.
The paper presents a new global three-dimensional model of the Earth thermosphere (for altitudes from 90 to 500 km) with a high spatial resolution. The model uses simple approximations for calculation of solar radiati...
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The paper presents a new global three-dimensional model of the Earth thermosphere (for altitudes from 90 to 500 km) with a high spatial resolution. The model uses simple approximations for calculation of solar radiation and ion-neutral interaction. A detailed description of the algorithm is presented. It is shown that the model represents the main features of the general thermospheric circulation with a satisfactory accuracy.
This paper proposes a scheme with innovation both in algorithm and method to construct and display three-dimensional (3D) objects. We reduce the number of needed images to establish the complete 3D objects by combinin...
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This paper proposes a scheme with innovation both in algorithm and method to construct and display three-dimensional (3D) objects. We reduce the number of needed images to establish the complete 3D objects by combining Wide Baseline Matching and 3D registration algorithm. We reduce the loss of edge and corner information by applying line detection and guided matching in Narrow Baseline Matching. We perform projective reconstruction with a dynamic threshold, and eliminate the ambiguity in Euclidean reconstruction by motion consistency constraint. We propose a fast linear method for motion calculation to recover the motion of key frames with a succinct method to obtain motion vector by solving linear equation set. We adopt a novel display system, which features high refresh rate, large size and high intensity screen, to provide live display of 3D objects. (C) 2012 Elsevier Ltd. All rights reserved.
We propose a branch and bound reduced algorithm for quadratic programming problems with quadratic constraints. In this algorithm, we determine the lower bound of the optimal value of original problem by constructing a...
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We propose a branch and bound reduced algorithm for quadratic programming problems with quadratic constraints. In this algorithm, we determine the lower bound of the optimal value of original problem by constructing a linear relaxation programming problem. At the same time, in order to improve the degree of approximation and the convergence rate of acceleration, a rectangular reduction strategy is used in the algorithm. Numerical experiments show that the proposed algorithm is feasible and effective and can solve small-and medium-sized problems.
This study proposes a new method for the detection of local invariant features with contour. This method differs from traditional methods that use image intensity. Image contours can be extracted stably with changes i...
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This study proposes a new method for the detection of local invariant features with contour. This method differs from traditional methods that use image intensity. Image contours can be extracted stably with changes in viewpoint, scale, illumination and other factors. The proposed algorithm first extracts the stable corner from the contour, then it fits the supporting region of the contour near the corner to an angle, and uses its bisector as the direction of the feature. Next, it searches the contour for the tangent point in the direction of the angle bisector. Finally, with the corner as the centre, and in combination with the tangent point and the feature direction, an elliptic invariant region is constructed. The feasibility of the algorithm was verified experimentally by comparing its repetition rate. Test images obtained from actual scenes include several types of transformations, such as rotation, scaling, affinity, illumination and noise. The results of the experiment show the feasibility of the proposed method for use in local invariant features detection.
A new denoising algorithm is proposed according to the characteristics of hyperspectral remote sensing image (HRSI) in the curvelet domain. Firstly, each band of HRSI is transformed into the curvelet domain, and the s...
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A new denoising algorithm is proposed according to the characteristics of hyperspectral remote sensing image (HRSI) in the curvelet domain. Firstly, each band of HRSI is transformed into the curvelet domain, and the sets of subband images are obtained from different wavelength of HRSI. And then the detail subband images in the same scale and same direction from different wavelengths of HRSI are stacked to obtain new 3-D datacubes of the curvelet domain. Again, the characteristics analysis of these 3-D datacubes is performed. The analysis result shows that each new 3-D datacube has the strong spectral correlation. At last, due to the strong spectral correlation of new 3-D datacubes, the multiple linear regression is introduced to deal with these new 3-D datacubes in the curvelet domain. The simulated and the real data experiments are performed. The simulated data experimental results show that the proposed algorithm is superior to the compared algorithms in the references in terms of SNR. Furthermore, MSE and MSSIM in each band are utilized to show that the proposed algorithm is superior. The real data experimental results show that the proposed algorithm effectively removes the common spotty noise and the strip noise and simultaneously maintains more fine features during the denoising process.
In this paper, a novel kernel-based limited-view computed tomography (CT) reconstruction model is proposed. First based on the classical Feldkamp-Davis-Kress (FDK) algorithm, the reconstruction kernel is derived. Then...
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In this paper, a novel kernel-based limited-view computed tomography (CT) reconstruction model is proposed. First based on the classical Feldkamp-Davis-Kress (FDK) algorithm, the reconstruction kernel is derived. Then according to the improved approximate inverse for limited view reconstruction, the FDK kernel is truncated to be compact, after which the ring artifacts is reduced. Finally an anisotropic diffusion governed by the Chambolle-Lions equation is introduced to suppress the other artifacts and noise. In the Chambolle-Lions equation, a threshold function is proposed to separate the regions with high or few features adaptively. The efficiency and accuracy of the method are shown in several numerical experiments. (C) 2012 Elsevier Ltd. All rights reserved.
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