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1.
首次指出,与Wolfe线搜索,Goldstein线搜索和精确线搜索等不同,在一般下降算法模型中使用Backtracking线搜索并不能保证全局收敛性。提出了一个改进方案,并在证明线搜索下降算法模型的一个一般全局收敛性定理的基础上,证明改进Backtracking线搜索方法能够保证全局收敛性。给出了改进Backtracking线搜索的下降算法至少线性收敛的一个充要条件。  相似文献   

2.
记忆梯度算法能求解大规模无约束优化问题,还具有避免大量存储和进行大规模矩阵运算的特点.在利用传统的记忆梯度算法时,最根本的问题是要解决迭代过程中所遇到的二维搜索问题.为了避免进行二维搜索,加快迭代收敛速度,对记忆梯度算法进行了改进,给出了一种改进的记忆梯度算法.改进的记忆梯度算法能有效地求解二维搜索问题,且计算量小,存储量亦小,从而使记忆梯度算法在非精确线性搜索的Wolfe原则下,有更好的实际意义.同时也对其全局收敛性进行了证明.  相似文献   

3.
给出了一个求解无约束优化问题的带不精确线性搜索的记忆梯度法。该方法利用以前迭代的更多信息来确定新的搜索方向,并用不精确线性搜索来选择迭代步长,证明了算法满足线性搜索的条件下的全局收敛性。数值试验结果显示,新算法具有较好的稳定性,对于求解大规模的问题,该算法显得更为有效。  相似文献   

4.
给出了新的PRP算法,该算法具有充分下降性和在无需任何线搜索的情况下自动保持搜索方向在可行域的特性,而且该算法在非凸函数和一致凸函数上具有全局收敛性,最后证明了新算法的线性收敛速度.  相似文献   

5.
针对模型信赖域方法中搜索方向存在的不足,提出了按负曲率方向进行搜索的模型信赖域算法,并证明了算法的收敛性,进一步地,将曲线线性搜索与模型信赖域方法结合,给出了一般的按曲线搜索方向进行线性搜索的模型信赖域方法,证明了这种搜索方法的可行性,这种方法具有搜索选择的灵活性和一般性,可在实际中针对不同的情况进行选择搜索方向,使得它具有曲线搜索的优点及模型信赖域方法的整体收敛性.最后,提出了几种常用方法的搜索方向可作为本方法的特殊形式。  相似文献   

6.
基于已有的DY方法,提出了一种改进的DY共轭梯度法(NMDY算法),该算法产生的搜索方向为充分下降方向,且这一性质与所采用的线搜索方法无关。并在一定的条件下证明了该算法基于Wolfe线搜索求解非凸优化问题的全局收敛性。  相似文献   

7.
提出一类PRP,HS,LS共轭梯度法的修正参数公式,改进方法的搜索方向自动充分下降.在标准WWP线搜索和新型MWWP线搜索下,证明了算法的全局收敛性.数值实验表明算法结果是有效的.  相似文献   

8.
针对基于群体适应度方差的自适应混沌粒子群算法存在的局部搜索能力较弱的不足,在该算法中引入了混沌变异以及混沌搜索操作。使用An混沌映射对部分粒子进行混沌变异,对全局最优粒子进行混沌搜索,提出了一种综合考虑粒子位置、寻优空间的自适应变尺度规则。数值仿真结果表明,改进算法的收敛性、全局和局部搜索能力都有所提高,能有效避免早熟收敛。  相似文献   

9.
利用Fischer—Burmeister函数,将约束最优化问题KKT系统转化为等价的非光滑方程组,利用广义导数,给出一个求解该非光滑方程组的BFGS方法。其子问题是一个系数阵为正定对称阵的线性方程组.为保证全局收敛性,我们引进了一个适当的线性搜索,它使得效益函数近似下降.在适当的条件下,我们证明了算法是适定的,并具有全局收敛性和超线性收敛性.  相似文献   

10.
提出了一种改进的PRP共轭梯度算法,其搜索方向自动具有充分下降性和信赖域性质,且在一定条件下,具有全局收敛性.数值结果表明该算法对求解无约束光滑问题是有效的.  相似文献   

11.
Service is a special product. It is intangible and unstored, so service er-rors are not avoided. Once service errors appear, the first line staffs who keep di-rect touch with customers wil play an important role in service recovery. The staffs' negative emotions during the recovery service should be recovered by internal ser-vice recovery. In this paper, critical incident technique is applied to analyse the re-covery strategies expected by the first line staff and the internal service recovery strategies such as inspiring, authorization, training and psychology service are put forward. the strategy most expected by the staff is reward.  相似文献   

12.
"Where" and "what" in vision   总被引:3,自引:0,他引:3  
D Sagi  B Julesz 《Science (New York, N.Y.)》1985,228(4704):1217-1219
The mixture of a few horizontal and vertical line segments embedded in an aggregate of diagonal line segments can be rapidly counted and their positions rapidly determined by a parallel (preattentive) process. However, the discrimination between horizontal and vertical orientation (that is, discrimination of a single conspicuous feature) requires serial search by focal attention. Under recent theories of attention, focal attention has been assumed to be required for the recognition of different combinations of features. According to the findings of this experiment, knowing "what" even a single feature is requires time-consuming search by focal attention. Only knowing "where" a target it is mediated by a parallel process.  相似文献   

13.
《农业科学与技术》2013,(10):1465-1467
The genetic parameters of main reproductive traits for the new Yorkshire line with high prolificacy were evaluated by multiple animal model DFREML The re- suits showed that the heritability evaluates of the total number of born (TNB), alive number of born (ANB), litter weigh at birth (LWB) and litter weight at age of 21 days were 0.10, 0.15, 0.09 and 0.14, respectively. The genetic correlations between these traits, for example, the correlations between TNB/ANB, NB/LWB, TNB/LW21, ANB/LWB, ANB/LW21 and LWB/LW21 were 0.87, 0.74, 0.43, 0.69, 0.59 and 0.51, respectively.  相似文献   

14.
《农业科学与技术》2013,(10):1443-1445,1461
The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /:2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two main selected traits such as total number of born and age at 100 kg weight was 12.17 piglets/litter and 165.18 d, respectively. The genetic improvements per generates was 0.156 and -2.198, respec- tively. The breeding objects of the new Yorkshire dam line with high prolificacy were basically reached. It indicated that the methods and index could be used in pig breeding.  相似文献   

15.
利用Moreau-Yosida正则化技术和非单调线搜索技术,设计了一种针对大规模非光滑优化问题的修正Hestenes-Stiefel共轭梯度算法.该算法的搜索方向不仅自动满足充分下降条件,而且属于信赖域.在适当条件下,新算法全局收敛.初步的数值实验也表明新算法对于求解大规模非光滑无约束凸优化问题是有效的.  相似文献   

16.
侧柏种源的地理变异趋势分析   总被引:5,自引:0,他引:5  
林木种源地理变异趋势研究是种源合理区划和种子调拔办限划定的基础工作。“Krige”技术是内插稀疏观测资料的随机方法。本文应用该方法探讨侧柏种源的地理变异趋势规律。  相似文献   

17.
两系亚种间杂交一季稻278S/中L208组合是籼型光温敏核不育系278S与粳稻广亲和恢复系中L208配制而成的。介绍了278S和中L208的选育经过及其特征特性。此外,还介绍了278S/中L208组合的高产栽培及其制种的技术。  相似文献   

18.
A large portion of irrigation farmers make use of subjective (intuition) irrigation scheduling methods as supposed to objective or scientific irrigation scheduling methods, which need to be changed. The BEsproeiingsWAterbestuursprogram (BEWAB+) irrigation scheduling programme is based on the water balance equation and needs: (1) a crop production function; (2) a relative consumptive water demand curve and (3) an allowable depletion subroutine. The objective of this paper was to describe research aimed at obtaining information on (1) and (2) for pea and also to describe the effect of water application on yield and water use of pea. BEWAB+ uses this information to estimate the daily irrigation water requirements for a particular soil-crop-atmosphere system under irrigation. A field experiment, based on published line-source irrigation methodology, was conducted on a 3 m deep loamy fine sand Bainsvlei or Ustic Quartzipsamment soil near Bloemfontein (26°08′S; 29°01′E) in South Africa. Results showed that there is a linear relationship of the form Ys = 8.07ET - 249 (r2 = 0.91), where Ys is the seed yield of pea (kg/ha) and ET is evapotranspiration for the growing season (mm). The relative consumptive water demand curve is represented by the following third order polynomial function that describes the relationship between time and relative ET for a pea growing season of 120 days: ETrelx = 0.09419646 - 0.01302413x + 0.00059008x2 - 0.00000371x3. ETrelz denotes relative ET and x denotes time in days. A workable balance between practical problem solving and advanced irrigation science has been established with BEWAB+. Pre-plant irrigation schedules can be made for semi-arid areas with the BEWAB+ programme using easily obtainable inputs, like target yield, soil depth and soil particle size distribution information.  相似文献   

19.
强Wolfe条件不能保证标准CD共轭梯度法全局收敛.本文通过建立新的共轭参数,提出无约束优化问题的一个新谱共轭梯度法,该方法在精确线搜索下与标准CD共轭梯度法等价,在标准Wolfe线搜索下具有下降性和全局收敛性.初步的数值实验结果表明新方法是有效的,适合于求解非线性无约束优化问题.  相似文献   

20.
Soybean mosaic virus (SMV) disease is one of the most destructive viral diseases in soybean (Glycine max (L.) Merr.). SMV strain SC3 is the major prevalent strain in huang-huai and Yangtze valleys, China. The soybean cultivar Qihuang 1 is of a rich resistance spectrum and has a wide range of application in breeding programs in China. In this study, F1, F2 and F2:3 from Qihuang 1×nannong 1138-2 were used to study inheritance and linkage mapping of the SC3 resistance gene in Qihuang 1. The secondary F2 population and near isogenic lines (nILs) derived from residual heterozygous lines (RhLs) of Qihuang 1×nannong 1138-2 were separatively used in the ifne mapping and candidate gene analysis of the resistance gene. Results indicated that a single dominant gene (designated RSC3Q) controls resistance, which was located on chromosome 13. Two genomic-simple sequence repeat (SSR) markers BARCSOYSSR_13_1114 and BARCSOYSSR_13_1136 were found lfanking the two sides of the RSC3Q. The interval between the two markers was 651 kb. Quantitative real-time PCR analysis of the candidate genes showed that ifve genes (Glyma13g25730, 25750, 25950, 25970 and 26000) were likely involved in soybean SMV resistance. These results would have utility in cloning of RSC3Q resistance candidate gene and marker-assisted selection (MaS) in resistance breeding to SMV.  相似文献   

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