基于人工蜂群算法的边坡最危险滑动面搜索

将用于连续数值优化问题的人工蜂群算法引入边坡稳定分析临界滑动面搜索领域.该方法模拟了蜂群的群体协作采蜜过程,具有自适应收敛的特点,克服了传统方法容易陷入局部最优的缺点,是一种全局优化算法.为进一步改善其在复杂边坡搜索中的效果,将Hooke-Jeeves模式搜索操作引入人工蜂群算法,提出一种用于边坡临界滑动面搜索的模式搜...     

Planning for robust reserve networks using uncertainty analysis

Planning land-use for biodiversity conservation frequently involves computer-assisted reserve selection algorithms. Typically such algorithms operate on matrices of species presence–absence in sites, or on species-specific distributions of model predicted probabilities of occurrence in grid cells. There are practically always errors in input data—erroneous species presence–absence data, structural and parametric uncertainty in predictive habitat models, and lack of correspondence between temporal presence and long-run persistence. Despite these uncertainties, typical reserve selection methods proceed as if there is no uncertainty in the data or models. Having two conservation options of apparently equal biological value, one would prefer the option whose value is relatively insensitive to errors in planning inputs. In this work we show how uncertainty analysis for reserve planning can be implemented within a framework of information-gap decision theory, generating reserve designs that are robust to uncertainty. Consideration of uncertainty involves modifications to the typical objective functions used in reserve selection. Search for robust-optimal reserve structures can still be implemented via typical reserve selection optimization techniques, including stepwise heuristics, integer-programming and stochastic global search.     

基于遗传模拟退火算法的频率指配算法研究

在复杂电磁环境中进行频率指配是频谱管理中极为重要且困难的研究课题。提出了一种基于遗传模拟退火算法的频率指配算法,以基本遗传算法为基础,采用自适应的交叉概率和变异概率,将遗传操作和模拟退火操作相结合,从而克服了一般遗传算法的不足,可有效避免陷入局部最优并最终趋于全局优化。理论分析和仿真结果表明,该算法能够给整个无线电网络合理地指配频率,同时能有效地控制算法自身的收敛速度,与传统的指配算法相比,新算法在指配效果上有了很大的提高。     

羧酸及其衍生物急性毒性的QSAR研究

基于定量结构-活性相关性(QSAR)原理,研究了27种羧酸及其衍生化合物结构与其急性毒性LC50之间的内在定量关系。应用遗传算法从大量结构参数中优化筛选出与LC50最为密切相关的五个参数作为分子描述符,得出影响羧酸及其衍生物急性毒性的主要结构特征为分子的大小及其空间效应等。分别采用支持向量机(SVM)方法和多元线性回归(MLR)方法建立了相应的QSAR预测模型,并对所建模型分别进行了内部验证和外部验证。结果表明,两种模型均具有较高的稳定性、预测能力及泛化性能。其中,支持向量机模型对训练集和预测集样本的预测平均绝对误差分别为0.149和0.211,优于多元线性回归方法所得结果。     

城市总体规划环境影响评价方法

开发不同类型规划的环境影响评价技术和方法是当前国内的热点研究领域之一.围绕城市总体规划特点,在分析识别规划经济增长和用地布局方案中存在的多种不确定性的基础上,以产业和用地为基本评估单元,综合运用蒙特卡罗随机采样技术和HSY算法,并将其与地理信息系统进行整合,建立了基于结构与空间不确定性分析的城市规划环评方法和系统评估模型.     

基于ICRP生物动力学模型的贫铀辐射危险估计算法

针对线性年龄相关剂量学程序PLEIADES （ Program for Linear Age - dependent Dosimetry）计算贫铀辐射危险存在的影响因素较多、系数不确定性大、使用不便的问题,基于ICRP生物动力学模型,采用美国原子管理委员会编制的放射性物质工具箱中提供的典型条件下铀的各同位素剂量转换系数,分析了不同背景下剂量的影响因素,给出了贫铀的辐射危险概率的简化计算方法,并同PLEIADES的结果相比较。分析表明两者结果吻合较好,该方法原理简单,使用方便,适合于对贫铀辐射危险的估算。     

Water quality monitoring in a slightly-polluted inland water body through remote sensing — Case study of the Guanting Reservoir in Beijing, China

This study focused on the water quality of the Guanting Reservoir, a possible auxiliary drinking water source for Beijing. Through a remote sensing (RS) approach and using Landsat 5 Thematic Mapper (TM) data, water quality retrieval models were established and analyzed for eight common water quality variables, including algae content, turbidity, and concentrations of chemical oxygen demand, total nitrogen, ammonia nitrogen, nitrate nitrogen, total phosphorus, and dissolved phosphorus. The results show that there exists a statistically significant correlation between each water quality variable and remote sensing data in a slightly-polluted inland water body with fairly weak spectral radiation. With an appropriate method of sampling pixel digital numbers and multiple regression algorithms, retrieval of the algae content, turbidity, and nitrate nitrogen concentration was achieved within 10% mean relative error, concentrations of total nitrogen and dissolved phosphorus within 20%, and concentrations of ammonia nitrogen and total phosphorus within 30%. On the other hand, no effective retrieval method for chemical oxygen demand was found. These accuracies were acceptable for the practical application of routine monitoring and early warning on water quality safety with the support of precise traditional monitoring. The results show that performing the most traditional routine monitoring of water quality by RS in relatively clean inland water bodies is possible and effective.     

基于覆盖水量的监测点优化选址法的缺陷与改进

研究了给水管网水质监测点选址的方法,分析了覆盖水量法存在的缺陷,针对这一缺陷,提出了一种基于覆盖水量指数的改进方法,在评价节点的代表性时,该方法同时考虑了总覆盖水量和覆盖水量时间分布对节点代表性的影响,提高了管网水质监测点优化选择的准确度和监测数据的代表性.为了提高优化问题求解的速度,采用了遗传算法求解水质监测点优化选址问题,并将此两类方法应用于2个案例管网.对于案例中的管网,采用布设7个监测点,可有效监控所有95个节点中85%以上的管网水量.同时,实际案例管网的应用表明,与覆盖水量法相比,覆盖水量指数法的计算结果具有更好的代表性,基于此建立的给水管网在线监测网络能够更好地代表管网的水质情况.     

大气污染总量控制GA方法中的多源模拟系统

大气污染总量控制的GA方法,是利用遗传算法(GA)的自适应全局搜索寻优功能,通过模拟的自然进化机制来求算经过全局优化的区域允许排放总量以及区域允许排放总量在区域内各污染源之间的分配方案的一种新的大气污染总量控制方法。在基于遗传算法的大气污染总量控制中,需要运用一个高效而可靠的大气污染多源模拟系统,以便根据源强分布快速计算出准确的浓度场。文章介绍了该大气污染多源模拟系统的设计与实现技术。