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1.
基于初值修正的组合灰色Verhulst模型   总被引:1,自引:0,他引:1  
对灰色Verhulst模型的拟合精度进行了分析,表明初值的选取对模型精度有重要影响.为提高灰色模型的拟合精度,利用最小二乘原理确定初值中的待定常数,给出了初值修正的灰色Verhulst模型.进一步利用修正模型和传统灰色Verhulst模型建立了组合灰色Verhulst模型,在平均相对误差最小的原则下,利用蚁群算法确定组合权系数.最后通过两个应用实例进行了计算和分析,结果表明,通过初值修正和组合模型能够提高灰色Verhulst模型的拟合精度,便于通过程序实现.  相似文献   

2.
通过对灰色Verhulst模型中白化方程的优化,以及利用新信息原理,得到一种改进的灰色Verhulst模型.最后,实例结果表明,该改进模型可以有效提高预测精度,从而拓宽了预测模型的使用范围.  相似文献   

3.
Verhulst模型的改进研究   总被引:2,自引:0,他引:2  
分析Verhulst预测模型的特点,并对灰色Verhulst预测模型的灰色微分方程定解问题中存在的初值问题提出了改进方案,其为提高模型的预测精度提供了一种新的途径.  相似文献   

4.
首先,基于灰色Verhulst的直接建模模型,对原始数据进行倒数生成,利用离散思想和序列累减,构建了倒数序列与倒数的一次累减序列间的关系式,并利用最小二乘法求解三参数;其次,从新关系式出发,构建了基于相邻的原始序列的新灰色Verhulst的离散直接建模模型,将三参数值代入即可求解模拟预测值;通过实例计算,表明模型的可操作性和优越性.  相似文献   

5.
通过分析传统灰色Verhulst模型利用倒数变换求解白化方程发现了灰色微分方程与白化方程不匹配而导致误差的根源,提出了直接对原始序列的一次累加序列作倒数变换后建立与倒数替换后的白化方程相匹配的灰色微分方程来估计参数a和b,并在此基础上将优化灰导数以改造灰色方程与利用平均相对误差最小为指标确定响应系数的方法相结合对模型进行了优化.结果表明,该优化模型对其本身的时间响应函数所表达的曲线进行模拟和预测具有重合性.通过实例分析说明了优化模型使得传统模型的模拟预测精度得到明显的提高.  相似文献   

6.
基于对灰色Verhulst模型的建模机理和数据特性进行了分析,表明可以通过适当的线性变换能够使变换后数据更适合灰色Verhulst模型的特征.根据两个应用实例说明利用适当的线性变换后建立的灰色Verhulst模型的精度有明显的降低.实例也说明了利用原始数据的线性变换建立Verhulst模型的可行性.  相似文献   

7.
继续对非等间隔灰色Verhulst模型病态性问题进一步深入研究,通过对模型线性化处理得出解的新形式,指出了非等间隔对解的影响程度,从矩阵条件数的角度分析并得到了模型线性化后存在病态性的主要原因是建模数据较大或呈现病态,并给出具体的改进措施.通过实例对比验证,对数据进行变换之后再建立线性化的非等间隔灰色Verhulst模型,其系数矩阵条件数和模型预测精度两方面均得到较大的改善即系数矩阵条件数达到良态且模型精度也比传统模型要高.本方法为其他灰色模型的病态性研究提供了一种参考.  相似文献   

8.
改进的GM(1,1)幂模型及其参数优化   总被引:1,自引:0,他引:1  
为了提高灰色GM(1,1)幂模型的拟合精度,对灰色GM(1,1)幂模型的背景值进行了改进,建立了一类改进GM(1,1)幂模型.利用粒子群优化算法给出了改进GM(1,1)幂模型的参数优化.实例分析结果表明基于粒子群算法的改进的GM(1,1)幂模型具有更高的预测和拟合精度.  相似文献   

9.
国防开支关乎军队的发展和战斗力的提升,是宏观经济预测的一项重要内容.利用Verhulst模型解决"小样本、不确定性"问题的优势对国防开支进行预测.首先对Verhulst模型机理进行了简要的叙述,说明其初值选取不合理是产生误差的一个重要原因;其次提出一种逆向预测的模型改进思路,通过设定迭代次数等参数,对传统的Verhulst模型的初值进行修正,建立一种基于逆向预测的Verhulst模型.采集我国2009-2016年国防开支数据进行实例检验,并对2017年国防开支进行预测,证明该模型能够有效提高预测精度.  相似文献   

10.
高速公路交通事故灰色Verhulst预测模型   总被引:4,自引:2,他引:2  
在分析我国高速公路交通事故历史数据的基础上,引入灰色Verhulst预测理论,建立了高速公路交通事故灰色Verhulst预测模型.通过对2000~2007年我国高速公路交通事故死亡人数进行实例分析,发现灰色Verhulst模型的预测精度高于GM(1,1)模型.结果表明,灰色Verhulst模型的预测结果较好的反映了高速公路交通事故的发展趋势,该模型用于高速公路交通事故预测是可行的.  相似文献   

11.
LUO Dang 《数学季刊》2005,20(1):34-41
In the model of geometric programming, values of parameters cannot be gotten owing to data fluctuation and incompletion. But reasonable bounds of these parameters can be attained. This is to say, parameters of this model can be regarded as interval grey numbers. When the model contains grey numbers, it is hard for common programming method to solve them. By combining the common programming model with the grey system theory, and using some analysis strategies, a model of grey polynomial geometric programming, a model of θpositioned geometric programming and their quasi-optimum solution or optimum solution are put forward. At the same time, we also developed an algorithm for the problem. This approach brings a new way for the application research of geometric programming. An example at the end of this paper shows the rationality and feasibility of the algorithm.  相似文献   

12.
ZHANGXIANGSUN(章祥荪)(InstituteofAppliedMathematicstheChineseAcademyofSciences,Beijing100080,China)ReceivedJune18,1994.Thisworki...  相似文献   

13.
A general model of local improvement algorithms in combinatorial optimization accurately confirms performance characteristics often observed in individual cases. The model predicts exponentially bad worst case and low order polynomial average run times for single optimum problems including some linear complementarity problems and linear programming. For problems with multiple local optima, most notably those that are NP-complete, average speed is linearly bounded but accuracy is poor.  相似文献   

14.
A procedure is proposed for the parametric linear programming problem where all the coefficients are linear or polynomial functions of a scalar parameter. The solution vector and the optimum value are determined explicitly as rational functions of the parameter. In addition to standard linear programming technique, only the determination of eigenvalues is required. The procedure is compared to those by Dinkelbach and Zsigmond, and a numerical example is given.  相似文献   

15.
Most research in robust optimization has been focused so far on inequality-only, convex conic programming with simple linear models for the uncertain parameters. Many practical optimization problems, however, are nonlinear and nonconvex. Even in linear programming, the coefficients may still be nonlinear functions of the uncertain parameters. In this paper, we propose robust formulations that extend the robust-optimization approach to a general nonlinear programming setting with parameter uncertainty involving both equality and inequality constraints. The proposed robust formulations are valid in a neighborhood of a given nominal parameter value and are robust to the first-order, thus suitable for applications where reasonable parameter estimations are available and uncertain variations are moderate. This work was supported in part by NSF Grant DMS-0405831  相似文献   

16.
The paper introduces the formulation of a probabilistic programming model to find the optimum mix proportion of aggregates to meet the specific grading requirement in order to minimize the cost which consists of the material cost and the expected penalty cost. The model is probabilistic since the gradation, which is the major parameter, is a random variable. A linear programming model is first formulated. Using the LP solution as initial value, a direct search technique is then employed to solve the problem. The model is expected to be applicable to any problem of aggregates blending. In this paper, however, the mixing aggregates of an asphalt mixing plant is exemplified to test the applicability of the model.  相似文献   

17.
A robust structural optimization scheme as well as an optimization algorithm are presented based on the robustness function. Under the uncertainties of the external forces based on the info-gap model, the maximization of the robustness function is formulated as an optimization problem with infinitely many constraints. By using the quadratic embedding technique of uncertainty and the S-procedure, we reformulate the problem into a nonlinear semidefinite programming problem. A sequential semidefinite programming method is proposed which has a global convergent property. It is shown through numerical examples that optimum designs of various linear elastic structures can be found without difficulty.The authors are grateful to the Associate Editor and two anonymous referees for handling the paper efficiently as well as for helpful comments and suggestions.  相似文献   

18.
We propose a decomposition algorithm for a special class of nonconvex mixed integer nonlinear programming problems which have an assignment constraint. If the assignment decisions are decoupled from the remaining constraints of the optimization problem, we propose to use a column enumeration approach. The master problem is a partitioning problem whose objective function coefficients are computed via subproblems. These problems can be linear, mixed integer linear, (non-)convex nonlinear, or mixed integer nonlinear. However, the important property of the subproblems is that we can compute their exact global optimum quickly. The proposed technique will be illustrated solving a cutting problem with optimum nonlinear programming subproblems.  相似文献   

19.
在证券组合投资过程中,忽略交易费用会导致非有效的证券组合投资,本文提出了一个考虑交易费用的证券组合投资的区间数线性规划模型,通过引入区间数线性规划问题中的目标函数优化水平参数λ和约束条件满足水平参数η将目标函数和约束条件均为区间数的区间数线性规划模型转化为确定型的一般线性规划模型,进而求得相应于优化水平λ和满足水平η的满意解.  相似文献   

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