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91.
Dividing Cubes算法生成的物体表面的法向量方向的光顺操作 总被引:1,自引:0,他引:1
在用DividingCubes算法提取的边界体素所构造的物体表面上,可能会存在法向量方向突变,使得物体表面光照图显示粗糙,文中提出了一种的领域加权平均法,对物体表面的法向量方向进行光顺处理,光顺操作只在相关边界体素间进行,并且对有多个等值面交汇的边界体素将不进行光顺操作,以避免模糊位于多个区域处的边界和保持物体表面光照图的细节,为避免在屏幕上产生孔洞,用光线投射法显示物体表面,文中所采用的光顺操作可以消除物体表面的法向量方向突变,使物体表面光照图光谱细腻,最后,给出一个医学图像的测试实例。 相似文献
92.
Marek Reformat Ronald R. Yager 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2008,12(6):543-558
A pervasive task in many forms of human activity is classification. Recent interest in the classification process has focused
on ensemble classifier systems. These types of systems are based on a paradigm of combining the outputs of a number of individual
classifiers. In this paper we propose a new approach for obtaining the final output of ensemble classifiers. The method presented
here uses the Dempster–Shafer concept of belief functions to represent the confidence in the outputs of the individual classifiers.
The combing of the outputs of the individual classifiers is based on an aggregation process which can be seen as a fusion
of the Dempster rule of combination with a generalized form of OWA operator. The use of the OWA operator provides an added
degree of flexibility in expressing the way the aggregation of the individual classifiers is performed. 相似文献
93.
N. Y. Kuznetsov 《Cybernetics and Systems Analysis》2000,36(2):188-195
The probability of monotone system failure on a fixed time interval is studied. The failure and repair distribution functions
are assumed to be of a general form. A new accelerated simulation method is proposed, which makes it possible to investigate
systems consisting of components with essentially different reliability characteristics.
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 45–54, March–April, 2000. 相似文献
94.
为了对政府采购中电子反向拍卖系统的适用性进行改善.利用多属性决策理论和相关算法,对多属性反向拍卖的步骤和模型进行研究.对只按价格来选取供应商的方式进行了改进,建立了多属性选取供应商的反向拍卖系统.系统实现了选取供应商的自动化,能达到综合属性的最优,满足政府采购中以反拍方式进行采购的需求,提高了采购效率,降低了采购成本. 相似文献
95.
In this study, the variable to be controlled over time is the number of defects. Meanwhile, the underlying distribution of defects is the geometric Poisson distribution, a Poisson distribution compounded by a geometric distribution. For production process control, the exponentially weighted moving average (EWMA) control scheme based on the geometric Poisson process is addressed. Performance of the EWMA control scheme is assessed not only by both in-control and out-of-control average run lengths (ARL’s), but also by higher moments of the run length (RL) distribution. The run length distribution properties can be obtained from the probability transition matrix and implemented using the computer programs developed in this study. With proper ARL and variance of RL selected, any small shift in mean can be detected via the geometric Poisson EWMA control scheme. 相似文献
96.
The Aerial Refueling Scheduling Problem (ARSP) can be defined as determining the refueling completion times for fighter aircrafts (jobs) on multiple tankers (machines) to minimize the total weighted tardiness. ARSP can be modeled as a parallel machine scheduling with ready times and due date-to-deadline window to minimize total weighted tardiness. ARSP assumes that the jobs have different ready times and a due date-to-deadline window between refueling due date and a deadline to return without refueling. In this paper, we first formulate the ARSP as a mixed integer programming model. The objective function is a piece-wise tardiness cost that takes into account due date-to-deadline windows and job priorities. Since ARSP is NP-hard, two heuristics are proposed to obtain solutions in reasonable computation times, namely (1) modified ATC rule (MATC), (2) a simulated annealing method (SA). The proposed heuristic algorithms are tested in terms of solution quality and CPU time through computational experiments with data randomly generated to represent aerial refueling operations of an in-theater air operation. Solutions provided by both algorithms were compared to optimal solutions for problems with up to 12 jobs and to each other for larger problems with up to 60 jobs. The results show that, MATC is more likely to outperform SA especially when the problem size increases, although it has significantly worse performance than SA in terms of deviation from optimal solution for small size problems. Moreover CPU time performance of MATC is significantly better than SA in both cases. 相似文献
97.
《国际计算机数学杂志》2012,89(7):1552-1573
Two direct pseudospectral methods based on nonclassical orthogonal polynomials are proposed for solving finite-horizon and infinite-horizon variational problems. In the proposed finite-horizon and infinite-horizon methods, the rate variables are approximated by the Nth degree weighted interpolant, using nonclassical Gauss-Lobatto and Gauss points, respectively. Exponential Freud type weights are introduced for both of nonclassical orthogonal polynomials and weighted interpolation. It is shown that the absolute error in weighted interpolation is dependent on the selected weight, and the weight function can be tuned to improve the quality of the approximation. In the finite-horizon scheme, the functional is approximated based on Gauss-Lobatto quadrature rule, thereby reducing the problem to a nonlinear programming one. For infinite-horizon problems, an strictly monotonic transformation is used to map the infinite domain onto a finite interval. We transcribe the transformed problem to a nonlinear programming using Gauss quadrature rule. Numerical examples demonstrate the accuracy of the proposed methods. 相似文献
98.
《国际计算机数学杂志》2012,89(5):1012-1029
Many problems in mathematics and engineering lead to Fredholm integral equations of the first kind, e.g. signal and image processing. These kinds of equations are difficult to solve numerically since they are ill-posed. Therefore, regularization is required to obtain a reasonable approximate solution. This paper presents a new regularization method based on a weighted H1 seminorm. Details of numerical implementation are given. Numerical examples, including one-dimensional and two-dimensional integral equations, are presented to illustrate the efficiency of the proposed approach. Numerical results show that the proposed regularization method can restore edges as well as details. 相似文献
99.
Fabian SobotkaThomas Kneib 《Computational statistics & data analysis》2012,56(4):755-767
Quantile regression has emerged as one of the standard tools for regression analysis that enables a proper assessment of the complete conditional distribution of responses even in the presence of heteroscedastic errors. Quantile regression estimates are obtained by minimising an asymmetrically weighted sum of absolute deviations from the regression line, a decision theoretic formulation of the estimation problem that avoids a full specification of the error term distribution. Recent advances in mean regression have concentrated on making the regression structure more flexible by including nonlinear effects of continuous covariates, random effects or spatial effects. These extensions often rely on penalised least squares or penalised likelihood estimation with quadratic penalties and may therefore be difficult to combine with the linear programming approaches often considered in quantile regression. As a consequence, geoadditive expectile regression based on minimising an asymmetrically weighted sum of squared residuals is introduced. Different estimation procedures are presented including least asymmetrically weighted squares, boosting and restricted expectile regression. The properties of these procedures are investigated in a simulation study and an analysis on rental fees in Munich is provided where the geoadditive specification allows for an analysis of nonlinear effects of the size of flats or the year of construction and the spatial distribution of rents simultaneously. 相似文献
100.
Yunqiang Yin Chin-Chia Wu Wen-Hsiang WuShuenn-Ren Cheng 《Computers & Operations Research》2012,39(5):1109-1116
This study addresses the problem of minimizing the total weighted tardiness on a single-machine with a position-based learning effect. Several dominance properties are established to develop branch and bound algorithm and a lower bound is provided to derive the optimal solution. In addition, three heuristic procedures are developed for near-optimal solutions. Computational results are also presented to evaluate the performance of the proposed algorithms. 相似文献