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1.
引进求解非线性极大极小问题的格雷码加速遗传算法(GAGA),给出GAGA算法实施的详细步骤,建立了GAGA相应的收敛定理。对GAGA的有效性和可行性进行了理论分析和实例分析。与一般的格雷码遗传算法(GGA)相比,GAGA具有准确、快速和适用性强等特点,是一种既可以较大概率搜索全局最优解,又能进行局部细致搜索的优秀非线性优化方法,可广泛应用于各种优化问题中。  相似文献   

2.
格雷码混合加速遗传算法及其性能分析   总被引:4,自引:0,他引:4  
通过在格雷码遗传算法进化过程中加入单纯形法学习算子,并利用格雷码遗传算法和单纯形法所得到的优秀个体群,作为变量新的变化范围,逐步缩小搜索空间,自动向最优解收缩,提出了求解非线性规划问题全局解的一种快速算法--格雷码混合加速遗传算法(GHAGA).为了在可行域内能得到全局最优解,在参数的定义域内投放了大量的均匀随机初始点作为初始群体.给出了GHAGA算法实施的详细步骤,建立了GHAGA相应的收敛定理,并分析了该算法的全局优化性能.理论分析和数值模拟表明,GHAGA具有精度高、收敛速度快的特点,是一种既可以较大概率搜索全局最优解,又能进行局部细致搜索的较好的非线性规划方法.  相似文献   

3.
进化策略能快速地搜索全局最优解。格雷码编码具有较强的局部搜索能力。针对Rosenbrock函数采用基于进化策略的格雷码来优化遗传算法,实验表明这种结合既能较快速地搜索适应度较大的个体,也可以大概率地搜索全局最优解。是一种快速进行局部细致搜索的优秀的非线性方法。  相似文献   

4.
解庆  赵小强 《甘肃科技》2013,29(2):13-16
遗传算法是—类基于自然选择和自然遗传机制的自适应全局优化概率搜索算法,编码策略是设计遗传算法的一个重要步骤,通过研究二进制码和格雷码的编码策略,分析了编码差异、个体差异和适应度差异之间的关系,得到了两种不同编码对遗传算子搜索能力的影响和它们的特性。  相似文献   

5.
混合编码遗传算法在测试数据生成中的应用   总被引:1,自引:1,他引:0  
针对传统遗传算法存在局部搜索能力差、未成熟收敛和多峰优化时常有漂移现象的缺陷,充分利用格雷码来消除Hammming悬岸问题,实数编码来获得大空间搜索任意精度的优势,从而获得混合编码的遗传算法.引人黄金分割点实现2种编码方法的转换,设计了测试数据生成的混合编码遗传算法.通过实例说明测试数据如何自动生成,结果表明生成测试数据的效果较好.  相似文献   

6.
利用混沌搜索的遍历性、随机性、规律性等特点,提出了一种求解离散变量结构优化设计的混沌搜索方法;将混沌搜索技术嵌入遗传算法,与基本遗传算子共同构成了一种离散变量结构优化设计的混合遗传算法一混沌遗传算法;通过自适应的退火因子和罚函数来处理约束条件,使算法逐渐收敛于全局可行最优解。计算结果表明,该方法有效地克服了基本遗传算法中的“早熟”现象,并具有更快的收敛速度。  相似文献   

7.
解非线性优化问题的混合加速遗传算法   总被引:2,自引:1,他引:2  
通过在实码遗传算法进化过程中加入改进的步长加速学习算子,并利用实码遗传算法和步长加速法所得到的优秀个体群,作为变量新的变化范围,逐步缩小搜索空间,自动向最优解收缩,提出了求解不可微非线性函数全局解的一种新方法——混合加速遗传算法(HAGA),给出了HAGA算法实施的详细步骤,建立了HAGA相应的收敛定理。理论分析和实例分析表明,HAGA具有准确、快速和适用性强等特点,是一种既可以较大概率搜索全局最优解,又能进行局部细致搜索的优秀非线性优化方法,可广泛应用于各种不可微函数优化问题中。  相似文献   

8.
自适应搜索的改进遗传算法及其应用   总被引:8,自引:0,他引:8  
提出了一种具有自适应搜索能力的快速收敛遗传算法。在计算过程中,设计变量的搜索范围依据每代自变量的数学期望和方差自动进行调整,并且通过引入进化策略中的自适应高斯变异算子,对变异算子进行改进,加速了算法的收敛性。为了验证算法的可行性和鲁棒性,对一个高维多峰函数的极小值搜索问题进行了求解,并将算法进一步应用于离心叶轮的形状优化问题。计算结果表明,该算法克服了传统遗传算法中设计区间的给定具有一定盲目性的缺陷,在收敛性和鲁棒性方面均优于传统的实数编码遗传算法。  相似文献   

9.
水文模型参数识别算法研究及展望   总被引:6,自引:0,他引:6  
就国内外水文模型参数识别算法的最新进展做了较为详细的阐述,特别对各种编码的遗传算法、单纯形混合加速遗传算法、模式搜索混合加速遗传算法、模拟退火混合加速遗传算法等现代优化算法在流域水文模型参数识别中的应用进行了研究,并与传统方法进行了比较;通过比较水文模型各参数优选方法的特点,认为混合加速遗传算法SHAGA,HJHAGA是一种较好的方法,具有较高的应用价值;同时对水文模型参数识别算法的发展前景进行了展望.  相似文献   

10.
遗传算法优化性能评价准则研究   总被引:8,自引:0,他引:8  
为了克服传统遗传算法优化性能评价准则(如在线性能、离线性能)忽略随机因素对算法的影响,从而不能准确评价算法性能的缺点,提出了一种基于平均偏离距和偏离距标准差的新的遗传算法优化性能评价准则,给出了平均偏离距和偏离距标准差的数学定义,并分析了它们的泛函意义.由于平均偏离距和偏离距标准差采用遗传算法多次运行结果的统计参数来评价算法的性能,因此能够较好地消除随机因素对算法性能的影响.同时,应用所提出的评价准则研究了二进制码和格雷码对遗传算法优化性能的影响.基于F2函数的数值实验结果表明,与二进制码相比,格雷码的平均偏离距和偏离距标准差指标都比较低,因此能够更好地提高遗传算法的优化性能.  相似文献   

11.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

12.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

13.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

14.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

15.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

16.
17.
The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.  相似文献   

18.
R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).  相似文献   

19.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

20.
The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.  相似文献   

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