遗传算法在甲流SIR模型参数求解中的应用

论文以全国甲型H1N1流行性感冒（下简称甲流）疫情数据为实例,讨论了采用SIR模型对甲流的传播过程进行模拟时相关参数的求解问题。分别通过优化的遗传算法（Genetic Algorithm,GA）和模拟退火算法（Simula-ted Annealing Algorithm,SA）求得该非线性模型中的重要参数阈值（日治愈率与日传染率的比值）,并由该参数阈值计算出各月患病人数。论文比较分析了两种算法在精度和效率上的优劣,发现遗传算法优于模拟退火。同时模拟结果验证了SIR模型适合甲流疫情的分析模拟。     

Quantitative Integration of High-Resolution Hydrogeophysical Data: A Novel Approach to Monte-Carlo-Type Conditional Stochastic Simulations and Implications for Hydrological Predictions

Geophysical techniques can help to bridge the inherent gap that exists with regard to spatial resolution and coverage for classical hydrological methods. This has led to the emergence of a new and rapidly growing research domain generally referred to as hydrogeophysics. Given the differing sensitivities of various geophysical techniques to hydrologically relevant parameters, their inherent trade-off between resolution and range, as well as the notoriously site-specific nature of petrophysical parameter relations, the fundamental usefulness of multi-method surveys for reducing uncertainties in data analysis and interpretation is widely accepted. A major challenge arising from such endeavors is the quantitative Integration of the resulting vast and diverse database into a unified model of the probed subsurface region that is consistent with all available measurements. To this end, we present a novel approach toward hydrogeophysical data integration based on a Monte-Carlo-type conditional stochastic simulation method that we consider to be particularly suitable for high-resolution local-scale studies. Monte Carlo techniques are flexible and versatile, allowing for accounting for a wide variety of data and constraints of differing resolution and hardness, and thus have the potential of providing, in a geostatistical sense, realistic models of the pertinent target parameter distributions. Compared to more conventional approaches, such as co-kriging or cluster analysis, our approach provides significant advancements in the way that larger-scale structural information contained in the hydrogeophysical data can be accounted for. After outlining the methodological background of our algorithm, we present the results of its application to the integration of porosity log and tomographic crosshole georadar data to generate stochastic realizations of the detailed local-scale porosity structure. Our procedure is first tested on pertinent synthetic data and then applied to a field dataset collected at the Boise Hydrogeophysical Research Site. Finally, we compare the performance of our data integration approach to that of more conventional methods with regard to the prediction of flow and transport phenomena in highly heterogeneous media and discuss the Implications arising.     

加权复合分位数自回归模型在隧道围岩变形预测中的应用

提出加权复合分位数自回归模型对隧道围岩变形进行预测的新方法,并给出其原理和实现算法。以昆明市阳宗隧道为例,对加权复合分位数自回归预测模型进行计算,并与其他模型进行对比分析。结果表明,新方法预测效果优于非加权复合分位数估值的AR(2)模型、基于最小二乘参数估计的自回归预测、经遗传算法优化的支持向量机等预测方法。     

用于地球物理反演的均匀设计优化算法

将均匀设计、模拟退火和单纯形方法相结合，提出一种全局优化迭代算法．数值模拟表明，它具有搜索速度快、搜索能力强和不需要求导数的特点，可用于地球物理反演研究．     

Using geostatistics to elucidate temporal change in the spatial variation of aeolian sediment transport

Little is known about the spatial and temporal scales of variation in aeolian processes. Studies that aim to investigate surface erodibility often sample aeolian sediment transport at the nodes of a regular grid of arbitrary size. Few aeolian transport investigations have the resources to obtain sufficient samples to produce reliable models for mapping the spatial variation of transport. This study reports the use of an innovative nested strategy for sampling multiple spatial scales simultaneously using 40 sediment samplers. Reliable models of the spatial variation in aeolian sediment transport were produced and used for ordinary punctual kriging and stochastic simulated annealing to produce maps for several wind erosion events over a 25 km² playa in western Queensland, Australia. The results support the existence of a highly dynamic wind erosion system that was responding to possibly cyclic variation in the availability of material and fluctuations in wind energy. The spatial scale of transport was considerably larger than the small scale expected of the factors controlling surface erodibility. Thus, it appears that transport cannot be used as a surrogate of erodibility at the scale of this investigation. Simulation maps of transport provided considerably more information than those from kriging about the variability in aeolian sediment transport and its possible controlling factors. The proposed optimal sampling strategy involves a nested approach using ca 50 samplers. Copyright © 2003 John Wiley & Sons, Ltd.     

正则参数控制下的波阻抗约束反演

通过势函数方式将波阻抗反演的病态问题转为良态问题，并且给出了边界保护势函数所具备的条件. 在反演过程中，通过改变正则参数数值以及合理地选择正则参数的初值，改善反演结果，提高反演收敛速度. 同时，在具体反演中使用快速模拟退火算法，可以克服目标函数局部极值的限制，从而获得全局最优解. 通过理论模型试算和实际资料处理，说明本文方法具有精度高、实用性强的特点.     

上海地震台阵(网)近震定位的翻台方法

为了快速而精确地确定震源位置，尽可能减少定位所产生的误差，引入了求解准则函数极小值的“POWELL”方法、“模拟退火法”、求解震源深度的“PTD方法”和“翻台法”用于近震定位。本文利用上述方法编制了近震定位程序，经过理论和实际应用的严格考察，已在全国部分数字化地震台网中推广使用，效果较好。     

改进的重力模拟退火反演研究

通过对模拟退火方法中常用的VFSA算法的分析，针对其在模型扰动及退火计划上存在的缺陷，针对性地作了更合理的改进VFSA算法，提高了VFSA算法的计算速度与稳健性，并结合重力反演过程中对模型的修正，克服了常规重力反演方法所存在的等值效应。研究中还把重力正演计算的单元体改为垂直侧边梯形单元，并合单同一层位的垂直侧边梯形单元成为一大单元再作计算，加快了正反演计算速度并提高了正反演精度。通过模型试验及实际资料的处理，验证了作者所提出的改进的模拟退火重力反演方法的有效性。