基于BP神经网络的饱和砂土液化判别方法

基于唐山地震中大量的砂土液化现场实测资料,选取描述地震动特性的烈度、震中距、地面峰值加速度和描述砂土层埋藏环境条件的地下水位、标贯点深度(土层深度)、上覆非液化覆盖土层厚度、有效覆盖压力,以及表示砂土自身属性的标准贯入锤击数、平均粒径、不均匀系数、修正标贯击数共11个指标的不同组合作为输入变量,采用快速BP算法和LM算法构造了饱和砂土液化判别的BP神经网络预测模型.通过所建网络模型的训练、验证和应用,结果表明:(1)所建14个BP神经网络模型都是有效的,液化判别的准确度与模型输入变量的不同组合有关;(2)增加网络模型的节点(考虑因素较多)并不一定能够提高BP神经网络模型的液化判别准确度,反而增加了BP神经网络模型的复杂性和学习时间;(3)两种算法的BP神经网络模型都有很高的液化判别准确度,LM算法的计算速率要比快速BP算法快得多,但在计算过程中需要更多的内存,建议采用LM算法;(4)采用所提BP神经网络模型的权值与阈值进行其它预测样本的液化判别时,判别结果可能偏于保守;(5)从影响砂土液化的主要因素、获取指标难易程度考虑,在与<建筑抗震设计规范>砂土液化判别公式考虑指标一致的情况下,建议采用BP神经网络模型M4或M5a,该模型简单、方便,且其预测准确度远高于<建筑抗震设计规范>的砂土液化判别准确度.     

城市应急物资配送路径支路限流模型研究

为科学、及时、合理地对城市应急物资进行调度,综合考虑突发事件发生后道路的实时通行状况,通过改变道路交通的交叉口限流以及物资运输路径,以最小化配送时间和成本为目标,构建1套完整的应急交通管制模型,使得所需的应急物资在被要求的最短时间窗内抵达受灾点;利用遗传算法进行编码设计求解模型,并通过仿真分析,设计配送路径的交叉口的支...     

遗传算法改进措施

标准遗传算法是一种导向随机搜索算法,具有较强的全局搜索能力.但遗传算法存在早熟收敛及收敛速度慢等问题,许多改进的遗传算法被提出,有效地克服或减轻了上述问题.参17.     

利用泥鳅红细胞核的遗传损伤监测福州市内河水质

利用泥鳅红细胞核的遗传损伤监测福州市内河水质,探讨红细胞核的遗传损伤与水质常规衡量指标间的相关性.结果表明:泥鳅红细胞微核率及核异变率的高低能够反映出河水的综合污染程度,差异达到显著或极显著.在一定范围内河水受污染程度越严重,微核及核异常率越高.但当染毒时间太长时,微核率及核异常率反而有所下降.微核率与水质的几项常规衡量指标间的相关程度依次为:高锰酸盐指数 >溶解氧 >氨氮比 >pH值;总核异常率与河水的几项常规指标间的相关程度依次为:高锰酸盐指数 >氨氮比>溶解氧>pH值.核异常率与微核率达到最高值的处理时间不完全同步.核异常率显著高于微核率,微核率与核异常率相关系数为 0. 44,这反映出生物体本身具有自动修复能力,能通过各种途径修复受损的DNA.此外,还探讨了泥鳅红细胞的微核来源和利用泥鳅红细胞核的遗传损伤监测河水水质的可行性及注意问题. 图 3表 6参 16     

柚类资源及其近缘种SSR标记的分子评价

采用31对SSR引物对122份柚类种质资源及其近缘种的遗传多样性进行了研究.31对SSR引物可以检测到335个等位基因变异,平均每个位点可检测到9.85个等位基因.每个位点多态性信息指数(PIC)平均值为0.7085.从这些引物中有效地筛选出21对高信息量SSR引物,与31对引物在122份柚类资源间遗传关系达到极显著相关(r=0.99104).柚类资源及其近缘种等位基因平均数(A)、平均杂合位点百分比(P)、SSR表型杂合度(H0)分别为2.8、83.54%、0.524.用UPGMA方法将122份研究材料分成7个组群,110个柚类品种在相似系数0.712时可细分成18个亚组,分类结果有利于今后有目的地利用这些丰富育种材料的遗传背景.图3表2参21     

青藏高原青稞B组醇溶蛋白遗传多样性研究

报道了青藏高原青稞B组醇溶蛋白的遗传多样性.在66份青藏高原青稞材料中,共有15种不同条带、29种不同条带组合,表明青藏高原青稞材料具有丰富的多态性.不同来源的群体材料间遗传多态性存在差异,西藏育成品种的多态性略低于四川农家品种,人工选择使其遗传多态性减弱.聚类分析将材料分成3组,材料聚类与材料来源地没有明显的相关性.图3表5参26     

医化废水驯化过程中细菌遗传多样性的RAPD分析

利用RAPD分子标记技术分析了医化废水驯化过程中细菌的遗传多样性. 结果表明:9种引物在5种浓度的废水驯化细菌中共扩增出134条带,其中88条表现为多态性,多态性位点百分率为65.7%. 根据Jacaard相异系数转换的距离矩阵,富集细菌与10%医化废水驯化细菌及20%医化废水驯化细菌之间的遗传距离最大,为0.750　0;而20%医化废水驯化细菌与40%医化废水驯化细菌之间遗传距离最小,为0.545　5. UPGMA法聚类结果表明,富集细菌与5%医化废水驯化细菌聚在一起组成一组;20%医化废水驯化细菌与40%医化废水驯化细菌先聚在一起,再与10%医化废水驯化细菌聚在一起组成另一组.      

A role for selective contraception of individuals in conservation

Contraception has an established role in managing overabundant populations and preventing undesirable breeding in zoos. We propose that it can also be used strategically and selectively in conservation to increase the genetic and behavioral quality of the animals. In captive breeding programs, it is becoming increasingly important to maximize the retention of genetic diversity by managing the reproductive contribution of each individual and preventing genetically suboptimal breeding through the use of selective contraception. Reproductive suppression of selected individuals in conservation programs has further benefits of allowing animals to be housed as a group in extensive enclosures without interfering with breeding recommendations, which reduces adaptation to captivity and facilitates the expression of wild behaviors and social structures. Before selective contraception can be incorporated into a breeding program, the most suitable method of fertility control must be selected, and this can be influenced by factors such as species life history, age, ease of treatment, potential for reversibility, and desired management outcome for the individual or population. Contraception should then be implemented in the population following a step‐by‐step process. In this way, it can provide crucial, flexible control over breeding to promote the physical and genetic health and sustainability of a conservation dependent species held in captivity. For Tasmanian devils (Sarcophilus harrisii), black‐flanked rock wallabies (Petrogale lateralis), and burrowing bettongs (Bettongia lesueur), contraception can benefit their conservation by maximizing genetic diversity and behavioral integrity in the captive breeding program, or, in the case of the wallabies and bettongs, by reducing populations to a sustainable size when they become locally overabundant. In these examples, contraceptive duration relative to reproductive life, reversibility, and predictability of the contraceptive agent being used are important to ensure the potential for individuals to reproduce following cessation of contraception, as exemplified by the wallabies when their population crashed and needed females to resume breeding.     

Synthesis of CuO nanoparticles through green route using Citrus limon juice and its application as nanosorbent for Cr(VI) remediation: Process optimization with RSM and ANN-GA based model

In present investigation, an attempt has been made for the synthesis of cupric oxide nanoparticles (CuONPs) through a green route by utilizing lemon juice extract as a bioreductant. The synthesized CuONPs were characterized through UV–visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The CuONPs were utilized for Cr(VI) removal from water through adsorption method in batch mode at different initial Cr(VI) concentration, pH, temperature and CuONPs dosage. The maximum uptake capacity of CuONPs was found to be 16.63 mg of Cr(VI)/g at pH 4.0. Implementation of response surface methodology (RSM) followed by artificial neural network hybridized with genetic algorithm (ANN-GA) approach has resulted maximum Cr(VI) adsorption of 98.8% under the optimized conditions of initial metal concentration 22.5 mg/L, pH 3.81, CuONPs dose 1.28 g/L and temperature 37.1 °C. Under optimum conditions, adsorption isotherm study was conducted, which showed that the fitness of experimental data was well achieved with Langmuir isotherm model illustrating monolayer pattern of adsorption. Thermodynamic study revealed that the process was spontaneous and endothermic in nature, while adsorption kinetics was best explained by pseudo-second order kinetic model.     

Effects of learning and adaptation on population viability

Cultural adaptation is one means by which conservationists may help populations adapt to threats. A learned behavior may protect an individual from a threat, and the behavior can be transmitted horizontally (within generations) and vertically (between generations), rapidly conferring population-level protection. Although possible in theory, it remains unclear whether such manipulations work in a conservation setting; what conditions are required for them to work; and how they might affect the evolutionary process. We examined models in which a population can adapt through both genetic and cultural mechanisms. Our work was motivated by the invasion of highly toxic cane toads (Rhinella marina) across northern Australia and the resultant declines of endangered northern quolls (Dasyurus hallucatus), which attack and are fatally poisoned by the toxic toads. We examined whether a novel management strategy in which wild quolls are trained to avoid toads can reduce extinction probability. We used a simulation model tailored to quoll life history. Within simulations, individuals were trained and a continuous evolving trait determined innate tendency to attack toads. We applied this model in a population viability setting. The strategy reduced extinction probability only when heritability of innate aversion was low (<20%) and when trained mothers trained >70% of their young to avoid toads. When these conditions were met, genetic adaptation was slower, but rapid cultural adaptation kept the population extant while genetic adaptation was completed. To gain insight into the evolutionary dynamics (in which we saw a transitory peak in cultural adaptation over time), we also developed a simple analytical model of evolutionary dynamics. This model showed that the strength of natural selection declined as the cultural transmission rate increased and that adaptation proceeded only when the rate of cultural transmission was below a critical value determined by the relative levels of protection conferred by genetic versus cultural mechanisms. Together, our models showed that cultural adaptation can play a powerful role in preventing extinction, but that rates of cultural transmission need to be high for this to occur.