共查询到20条相似文献，搜索用时 31 毫秒
1.
在多目标最优化问题的研究中,围绕最优解涌现了很多成果,产生了不少解的概念㈤。对于通常的单目标最优化问题解的唯一性以及稳定性,也有过一些通有性的研究成果。对于多目标最优化问题解的稳定性,Yu曾给出了一个通有稳定性结果,Xiang也曾给出了当权因子,权因子和目标函数变化时加权解的稳定性结果。鉴于在实际运用中,加权方法和加权解的作用突出,因此研究加权解的稳定性具有重要意义。在本文中,将在Xiang的基础上研究引入计算机一些应用知识当权因子,目标函数和约束集合都变化时多目标优化加权解的稳定性,最后通过计算机模拟阐述现实中的一个例子说明稳定的加权解在现实应用中如何选择满意的解要依实际情况而定。 相似文献
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A Chebyshev collocation method, an expansion method, has been proposed in order to solve the systems of higher-order linear integro-differential equations. This method transforms the IDE system and the given conditions into the matrix equations via Chebyshev collocation points. By merging these results, a new system which corresponds to a system of linear algebraic equations is obtained. The solution of this system yields the Chebyshev coefficients of the solution function. Some numerical results are also given to illustrate the efficiency of the method. Moreover, this method is valid for the systems of differential and integral equations. 相似文献
3.
There are few techniques available to numerically solve linear Fredholm integrodifferential-difference equation of high-order. In this paper we show that the Taylor matrix method is a very effective tool in numerically solving such problems. This method transforms the equation and the given conditions into the matrix equations. By merging these results, a new matrix equation which corresponds to a system of linear algebraic equation is obtained. The solution of this system yields the Taylor coefficients of the solution function. Some numerical results are also given to illustrate the efficiency of the method. Moreover, this method is valid for the differential, difference, differential-difference and Fredholm integral equations. In some numerical examples, MAPLE modules are designed for the purpose of testing and using the method. 相似文献
4.
一种规整化的各向异性扩散相干斑抑制算法 总被引：2，自引：0，他引：2
针对基于各向异性扩散的相干斑抑制算法 (SRAD)中存在的不合理性 ,即算法在均匀区域内降噪特性一般 ,并且扩散系数的非凸可能导致解不收敛到正确的图像 ,从理论上进行了系统的分析和论证 ,并依据保持图像细节的规整化准则 ,构造出新的扩散控制系数 .在此基础上 ,进一步提出了一种更合理的规整化各向异性扩散模型 (RSRAD) ,该模型可以有效地克服SRAD中存在的不合理性 .实验结果表明 ,RSRAD算法优于SRAD . 相似文献
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《Journal of The Franklin Institute》2022,359(11):5341-5353
In this study, a robust fractional-order controller design methodology for a type of fractional-order or integer-order model with dead time is proposed using phase and gain margin specifications. The delayed Bode’s ideal transfer function is used as a reference model to design the controller analytically. The delay term in delayed Bode’s ideal transfer function provides the exact determination of these frequency domain specifications when the system owns a dead time. The analytical robust controller design problem is transformed to solving four nonlinear equations with four unknown variables, two of which are the desired specifications; namely, phase and gain margins. The remaining two are the phase and gain cross-over frequencies. Next, some conditions are set based on the desired specifications so that nonlinear equations provide a unique solution. The proposed method is compared with the other existing robust controller methods based on the same frequency domain specifications. The simulation results reveal that the proposed method outperforms the other methods and also gives closer outcomes to the desired specifications. 相似文献
6.
近年来,科技项目作为政府支持初创期中小企业发展的有效手段,使得很多企业因此受益。而初创期企业由于自身条件所限,申报科技项目的水平和能力明显不足,提高企业申报科技项目的能力,是很多初创期企业的需求,但靠自身能力无法实现。基于TRIZ理论体系,综合利用系统功能分析、资源分析、物场分析等方法分析问题产生的原因,提出原理解并结合实际讨论求得可行方案,在此基础上提出对策建议。 相似文献
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所谓标准化方法的评价功能就是根据标准化得分直接进行优劣判断,评价方法的评价功能就是根据评价值的大小直接进行优劣判断,这两个问题是学术评价的基础方法论问题,长期没有得到重视,并且被排序分析所掩盖。文章以TOPSIS方法为例,认为sigmoid标准化具有评价功能,并以JCR2017无机与核化学期刊为例进行了实证研究。研究结果表明:评价值的评价功能受指标标准化方法与评价方法的影响;sigmoid标准化方法具有评价功能;现有的极大值标准化、极差标准化、功效系数法标准化方法均不具备评价功能;TOPSIS评价方法具有评价功能;sigmoid标准化改变了指标的统计特征;sigmoid标准化TOPSIS评价结果与极大值标准化有所差异;sigmoid标准化TOPSIS评价改变了评价值的统计特征;标准化与评价方法的评价功能对学术评价冲击较大。 相似文献
8.
In electroporation, an electric field transiently permeabilizes the cell membrane to gain access to the cytoplasm, and to deliver active agents such as DNA, proteins, and drug molecules. Past work suggests that the permeabilization is caused by the formation of aqueous, conducting pores on the lipid membrane, which are also known as electropores. The current-voltage relation across the membrane-bound pores is critical for understanding and predicting electroporation. In this work, we solve the Nernst–Planck equations in a geometry encompassing an isolated electropore to investigate this relation. In particular, we study cases where the intra- and extracellular electrical conductivities differ. We first derive an analytical solution, which is subsequently validated with a direct numerical simulation using a finite volume method. The main result of the current work is a formula for the effective pore resistance as a function of the pore radius, the membrane thickness, and the intra- and extracellular conductivities. This formula can be incorporated into whole-cell or planar-membrane electroporation models for system-level prediction and understanding. 相似文献
9.
The paper considers a process controlled by a system of delayed differential equations. Under certain assumptions, a control function is determined such that the zero solution of the system is asymptotically stable and, for an arbitrary solution, the integral quality criterion with infinite upper limit exists and attains its minimum value in a given sense. To solve this problem, Malkin’s approach to ordinary differential systems is extended to delayed functional differential equations, and Lyapunov’s second method is applied. The results are illustrated by examples, and applied to some classes of delayed linear differential equations. 相似文献
10.
《Journal of The Franklin Institute》2021,358(13):6818-6834
This paper proposes an extended comparison principle for continuous-time linear positive time-delay systems. Unlike the existing comparison principle, which uses a constant initial function for the comparison system, instead, we propose a time-varying initial function in order to derive a more general solution comparison. Based on this extended comparison principle, we develop a novel computational method, which exploits more effectively the information of the initial value function, to derive tighter exponential estimates for the state vector of positive time-delay systems. The effectiveness of our developed method is illustrated through two numerical examples. 相似文献
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本文以案例研究法,对围绕陶瓷生产企业——JS集团公司的成本特点作了具体的分析,并在此基础上提出基于作业成本法的成本优化方案,以期提高公司成本管理效益。 相似文献
13.
为了提高运输规划问题的有效性,降低运输成本,将遗传算法引入到该问题的求解中。运输规划问题的数学模型是带约束的函数优化问题,在该问题模型中引入遗传算法,采用罚函数法处理约束条件,对可行解和不可行解采用不同的适应值函数,结合轮盘赌、竞标赛和精英保存算法作为选择策略,对可行解和不可行解分别采用边界变异和非均匀变异,最终得出最优解。实验结果数值说明该方法的有效性。 相似文献
14.
In this paper, the Bagley-Torvik equation, which has an important role in fractional calculus, is solved by generalizing the Taylor collocation method. The proposed method has a new algorithm for solving fractional differential equations. This new method has many advantages over variety of numerical approximations for solving fractional differential equations. To assess the effectiveness and preciseness of the method, results are compared with other numerical approaches. Since the Bagley-Torvik equation represents a general form of the fractional problems, its solution can give many ideas about the solution of similar problems in fractional differential equations. 相似文献
15.
In this paper, we study an adaptive random search method based on continuous action-set learning automaton for solving stochastic optimization problems in which only the noise-corrupted value of function at any chosen point in the parameter space is available. We first introduce a new continuous action-set learning automaton (CALA) and study its convergence properties. Then we give an algorithm for optimizing an unknown function. 相似文献
16.
In this paper, a numerical method based on polynomial approximation, using Hermite polynomial basis, to obtain the approximate solution of generalized pantograph equations with variable coefficients is presented. The technique we have used is an improved collocation method. Some numerical examples, which consist of initial conditions, are given to illustrate the reality and efficiency of the method. In addition, some numerical examples are presented to show the properties of the given method; the present method has been compared with other methods and the results are discussed. 相似文献
17.
In this study, the homotopy analysis method (HAM) is used to obtain an approximate analytical solution for geometrically non-linear vibrations of thin laminated composite plates resting on non-linear elastic foundations. Geometric non-linearity is considered using von Karman’s strain-displacement relations. Then, the effects of the initial deflection, ply properties, aspect ratio of the plate and foundation parameters on the non-linear free vibration is studied. Comparison between the obtained results and those available in the literature demonstrates the potential of HAM for the analysis of such vibration problems, whose governing differential equations include the quadratic and cubic non-linear terms. This study shows that only a first-order approximation of the HAM leads to highly accurate solutions for this type of non-linear problems. 相似文献
18.
An impulsive reaction-diffusion periodic food-chain system with Holling type III functional response is presented and studied in this paper. Sufficient conditions for the ultimate boundedness and permanence of the food-chain system are established based on the upper and lower solution method and comparison theory of differential equation. By constructing appropriate auxiliary function, the conditions for the existence of a unique globally stable positive periodic solution are also obtained. Some numerical examples are shown to illustrate our results. A discussion is given in the end of the paper. 相似文献
19.
在科学和工程技术实例应用中,有许多数学模型是以常微分方程的形式建立起来的。因此,常微分方程求解问题是一个在科学计算中占有相当重要地位的问题。由常微分方程的理论可以看到,虽然许多常微分方程的解是存在的,但是却并不能用简单的初等函数来表现出来,甚至有的不能给出解的具体表达形式。因此,对于常微分方程初值问题的数值解法的研究是非常必要的。本文主要介绍了两种单步法,即欧拉法和改进的欧拉法来求解常微分方程初值问题,并通过具体的数值算例来进行比较,表明改进的欧拉法具有一定的优势。 相似文献
20.
Mehrnoush Davanipour Alireza Khayatian Maryam Dehghani 《Journal of The Franklin Institute》2017,354(14):5949-5963
In this paper, a solution for improvement of transient performance in adaptive control of nonlinear systems is proposed. An optimal adaptive controller based on a reset mechanism and a prescribed performance bound is devised. The suggested controller has the structure of adaptive backstepping controller in which the estimated parameters are reset to an optimal value. The designed controller ensures both the transient bound and the asymptotical convergence of the states. It is shown that the tracking error satisfies the prescribed performance bound all the time, besides the speed of the convergence rate is increased by resetting the estimated parameters. The results have been proved through both the analytical and simulation studies. The proposed method is applied to an Augmented Quarter Car Model as a case study. Simulation results verify the established theoretical consequences that the prescribed performance bound based optimal adaptive reset controller can enhance the transient performance of the adaptive controller. 相似文献