共查询到18条相似文献，搜索用时 156 毫秒
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非线性方程最优拟合的缩张算法 总被引：22，自引：3，他引：19
本文提出一种可实现非线性方程最优拟合的新方法－缩张算法（Ｃ－Ｅ算法）。该算法由若干循环组成,每一循环都包含收缩和扩张两个步骤。因而,可以在多维起始空间的内、外漫游搜索目标函数,并利用搜索过程所反馈的信息调整搜索中心和步长;通过较少次Ｃ－Ｅ循环的搜索,便能逼近给定非线性方程的最适参数值。该算法不需要给出方程的导数或偏导数,减少了计算的复杂性,也可能推广应用于解决其它目标函数的最优化问题。 相似文献
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数量性状分离分析中分布参数估计的IECM算法 总被引：51，自引：5，他引：46
在主基因＋多基因混合遗传分析中, 随着模型的扩展, 估计成分分布参数的EM算法 显 示其局限性。 本文在ECM算法和剖分成分分布方差为主基因、 多基因及环境三种方差组分 基 础上, 推演出S个CM步骤的一般迭代公式, 称为迭代ECM算法(简称IECM算法)。 文中 给出利用 个别分离世代鉴定主基因和多基因存在, 以及利用联合多个 相似文献
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文章分析了植物育种数据分析现状，指出了植物育种应用BLUP育种值理论和分析方法遇到的问题，并给出了相应的解决对策。 相似文献
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粮食的储备对于一个国家来说十分重要,是关乎民生的重要战略资源。储粮对于温度要求十分严格,机械通风是保持粮仓环境温度的重要方法。针对传统机械通风不能准确识别通风时机而导致的风机损耗和粮食损害问题,选用RBF神经网络建立温度预测模型,利用粒子群算法（Particle Swarm Optimization,PSO）及列文伯格-马夸尔特算法（Levenberg-Marquard,LM）优化网络的参数。仿真结果可以看出,用PSO算法和LM算法优化后的神经网络模型预测精度更加准确,与用PSO优化后的RBF神经网络进行比较后可知,PSO-LM-RBF算法预测误差小,模型更加稳定。 相似文献
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采用蚁群算法对食品机械四杆机构进行最优化设计,分析建立杆尺寸间的几何联系,并结合具体实例确定四杆机构各个参数。介绍了蚁群算法的模型和算法实现过程。说明了蚁群算法应用于机械优化计算切实可行,它使设计快速、计算精确、设计结果可靠,为复杂的机械优化设计问题提供了新的思路和方法。 相似文献
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用BASIC语言编制出育种畜禽系谱数据管理程序.采用数据随机存取文件的方式,利用SPACE＄命令解决了用等长字节的记录存取育种畜禽个体不等长代号名的矛盾.操作简单,使用方便,通用性强,为期保存和利用育种畜禽系谱数据,提供了一个实用性程序. 相似文献
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铁春6号小麦新品种是由铁岭市农科院以龙麦15为母本、中8607品系为父本进行有性杂交,经过6个世代系谱选育而成.原系谱号90091-6-1-12-1-1.2003年经辽宁省农作物新品种审定委员会审定. 相似文献
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Jean-Luc Jannink 《Euphytica》2008,161(1-2):61-69
Failures of the additive infinitesimal model continue to provide incentive to study other modes of gene action, in particular,
epistasis. Epistasis can be modeled as a QTL by genetic background interaction. Association mapping models lend themselves
to fitting such an interaction because they often include both main marker and genetic background factors. In this study,
I review a model that fits the QTL by background interaction as an added random effect in the now standard mixed model framework
of association analyses. The model is applied to four-generation pedigrees where the objective is to predict the genotypic
values of fourth-generation individuals that have not been phenotyped. In particular, I look at how well epistatic effects
are estimated under two levels of inbreeding. Interaction detection power was 8% and 65% for pedigrees of 240 randomly mated
individuals when the interaction generated 6% and 20% of the phenotypic variance, respectively. Power increased to 21% and
94% for these conditions when evaluated individuals were inbred by selfing four times. The interaction variance was estimated
in an unbiased way under both levels of inbreeding, but its mean squared error was reduced by 40% to 70% when estimated in
inbred relative to randomly mated individuals. The performance of the epistatic model was also enhanced relative to the additive
model by inbreeding. These results are promising for the application of the model to typically self-pollinating crops such
as wheat and soybean.
The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
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讨论了近亲交配群体在世代交替中配子间平均互信息性质;定义了配子间的近交关联信息系数,并与近交系数比较,阐述了配子间的近交关联信息系数的优点。结果表明,应用信息论模型研究群体遗传学与以往统计学方法具有一致性,而且还具有信息学的意义和优点。 相似文献
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为了以最佳的选育途径育成新的矮牵牛雄性不育“两用系”。设计了2种选育途径获得新的矮牵牛雄性不育“两用系”,即连续自交保留不育株分离株系和在不育株分离株系系内兄妹交2种方法。比较两种方法在观赏性状的纯合效果,并对不同世代矮牵牛进行花径、花葶、株高的调查。结果表明BC2F2代系内兄妹交和连续自交的花径平均变异系数分别为8.26%和6.13%,BC3F2代系内兄妹交和连续自交的花径平均变异系数分别为4.20%和2.15%。随着世代的增加,自交的变异系数逐渐变小,基因型纯合速度更快。连续自交比系内兄妹交的变异系数小,连续自交是获得矮牵牛雄性不育“两用系”的最佳选育方法。发现优先模式,加快矮牵牛的F1代选育进程,为矮牵牛育种提供技术依据。 相似文献
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A variety cross diallel of five populations of maize (Zea mays L.) was evaluated in a cool, temperate environment. Two of the parental populations were Corn Belt Dent synthetics (AS3 and BS22), one was developed from selected lines from a CIMMYT population developed for highland regions of the tropics and four Corn Belt Dent inbred lines (NZS3), and the other two had the pedigrees ‘Criollo de Toluca’× AS32 (NZS1) and ‘San Gerónimo’× BS222 (NZS2). ‘Criollo de Toluca’ is from the highlands of Mexico and ‘San Gerönimo’ is from the highlands of Peru. The objective was to study the influence of introgressing highland tropical germplasm into elite Corn Belt Dent synthetics on genetic effects, especially inbreeding depression, and to develop recommendations for the utilization of the introgressed populations. Inbreeding depression explained the greatest proportion of the variation among entries for grain yield, days to silking and plant height, but not for grain moisture at harvest and root lodging. For grain yield, NZS1, NZS2, and NZS3 had high levels of inbreeding depression and the difference between NZS1 and AS3 was statistically significant. High levels of root lodging were associated with NZS1 and high grain moisture at harvest with NZS2. These results indicate that a recurrent selection method, such as S1 selection, which effectively reduces inbreeding depression, should be used in early cycles of selection with introgressed populations containing highland tropical germplasm. 相似文献
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马氏珠母贝选系F4遗传结构和亲缘关系建分析 总被引：3，自引：2，他引：1
为了有效避免因近交引起性状退化,本实验利用微卫星标记分析了选系F4的遗传结构,并估计了其有效亲本的数量。2010年9月,从快速生长系F3选择亲本进行子代繁殖,雌雄亲本数量分别为42和38个,人工解剖授精,按照常规技术进行幼体培育和海区养殖。2011年6月,从选系F4随机选取90个个体,利用45对微卫星引物进行遗传结构分析和有效亲本数量的推断。结果表明：45个微卫星位点共检测到186个等位基因,每个位点的等位基因数在2~9之间,平均每个位点有4.13个等位基因。平均观察杂合度为0.543;平均期望杂合度为0.542;平均Shannon多样性指数为1.012;平均PIC值为0.491。根据基因频率的似然率算法成功的推断出该群体含有30个全同胞家系,用于繁殖选系F4有效亲本数量为60个,有75%的亲本参与了繁殖。世代之间近交系数增量△F=0.83%,F4代群体的近交系数F=3.27%。本研究结果表明：（1）该选系F4具有较高的遗传变异;（2）利用微卫星标记能有效推算选系的有效亲本数量,同时为构建继代群体提供技术支持。 相似文献
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In this paper, the Artificial Neural Network (ANN) is applied to the internal force analysis of structure. After introducing the model and algorithm of back-propagation network, a trained BP network of three layers is used to calculate the maximum of elastic moment of middle span of two-way slab. In order to enhance the generalized capability of network, the modified value of weight should be regarded as convergence standard and in order to accelerate the learning process without vibration, the method of adding momentum coefficient is adopted. The analysis program of BP network is carried out with the software of Matlab. The result demonstrates that application of ANN in structure analysis is feasible. 相似文献
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For the fall point calculation problem of Rocket Wreckage,the kinetic traits of rocket wreckage is analyzed, and the influence of the atmosphere resistance to wreckage fall point is studied mainly. The fall point algorithm of rocket wreckage adopting atmosphere resistance modification is proposed. Comparing with the traditional fall point algorithm, in the proposed method, the influence of layered atmosphere density of fall-point area is considered properly, and the air resistance coefficient is estimated according to the air dynamic equation of fall process, the integral method is adopted to get the moving track of the rocket wreckageand the final fall point. The effectiveness of the algorithm is validated by analyzing the fall points of the first stair of the rocket in four tasks corresponding to four types of rockets. 相似文献
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Francielly de Cássia Pereira Adriano Teodoro Bruzi José Wilacildo de Matos Breno Alvarenga Rezende Luis Claudio Prado José Airton Rodrigues Nunes 《Plant Breeding》2017,136(5):679-687
The goal of this study was to verify the influence of the population effect in the estimates of genetic and phenotypic components and to identify the best soybean progeny or lines in a commercial soybean breeding programme. We evaluated 292 populations for grain yield and absolute maturity during three agricultural years. To quantify the efficiency of the inclusion of the population's effect in the model, we estimated genetic gain with the selection, the Spearman's correlation, the coincidence index, the realized gain and correlated response of selected genotypes with and without the effect of the population. It was found that the variance components, heritability and coefficient of experimental variation were better estimated when the effect of the population was included, providing greater gain with selection for grain yield and absolute maturity. Coincidence and ranking among the selected progeny with and without the effect of the population are of greater magnitude in more advanced inbreeding generations and at higher percentage of selected progeny. The use of the population effect has greater importance in earlier generations of inbreeding. 相似文献