安装MR阻尼器工程结构的非参数模型自适应控制

本文首先建立了结构一磁流变阻尼器非线性系统的非参数模型,该模型不需要太多的受控结构的先验知识,且具有结构简单、参数少,是时变增量形式等优点,因此适合于非线性控制系统的设计。在此基础上,本文提出了非参数模型学习自适应半主动控制算法,并以一个6层框架结构为例,进行了深入的仿真数值分析。计算结果表明,采用本文提出的控制算法能得到令人满意的控制效果。通过在较大范围内选取结构参数值,验证了算法具有较好的鲁棒性。     

混合星座星间链路的建立以及连通性和稳健性分析

首先,分析了混合星座的特点,并分别讨论了GEO卫星、IGSO卫星和Walker-δ星座的服务性能和星间链路的建立特点;然后,运用邻接矩阵给出混合星座连通性的判断标准,运用任意两颗卫星间相连途径的数目、割点、割边、k-连通度和k-边连通度给出星间链路稳健性的判断标准,并给出了星座达到k-连通所需要的最少星间链路的数目及其构建方式;最后,对模拟的3GEO+3IGSO+24MEO星座构型中各卫星之间的星间链路建立准则、连通性和稳健性进行了分析。     

Comparison of hydrological models for use in climate change studies: A test on 241 catchments in West and Central Africa

The present work reports on the study and the comparison of the performance of three “Génie rural” (GR) and two Water Balance (WB) models. The calibration and robustness performances are analysed in the light of the hydro-climatic conditions. The study shows that the GR models are much more efficient and robust than the WB models. The behaviour of calibration performance as a function of hydroclimatic variables varies according to the model and goodness-of-fit criteria (GOFC). The GR models are more robust in terms of NSE(Q) and NSE(√Q) and the WB models in terms of KGE. For more robustness of the models, it is better to transfer the parameters to wetter periods or periods with a lower Potential EvapoTranspiration (PET) than the calibration period. For a loss of robustness of less than 20% for GR and 30% for WB, the variation between calibration and rain validation/PET periods must be around ±15%/±1.5%.     

Six factors which affect the condition number of matrices associated with kriging

Determining kriging weights to estimate some variable of interest at a given point in the field involves solving a system of linear equations. The matrix of this linear system is subject to numerical instability, and this instability is measured by the matrix condition number. Six parameters in the kriging process have been identified which directly affect this condition number. Analysis of a series of 648 experiments gives some insight on these parameters, and how the condition number relates to kriging variance.     

Separating wheat from chaff: Diatom taxon selection usingan artificial neural network pruning algorithm

This study addresses the question of what diatom taxa to includein a modern calibration set based on their relative contribution in apalaeolimnological calibration model. Using a pruning algorithm for ArtificialNeural Networks (ANNs) which determines the functionality of individual taxa interms of model performance, we pruned the Surface Water Acidification Project(SWAP) pH-diatom data-set until the predictive performance of thepruned set (as assessed by a jackknifing procedure) was statistically differentfrom the initial full-set. Our results, based on the validation at each5% data-set reduction, show that (i) 85% of the taxa canbe removed without any effect on the pH model calibration performance, and (ii)that the complexity and the dimensionality reduction of the model by theremoval of these non-essential or redundant taxa greatly improve therobustness of the calibration. A comparison between the commonly usedmarginal criteria for inclusion (species tolerance andHill's N2) and our functionality criterion shows that the importance ofeach taxon in an ANN palaeolimnological model calibration does not appear todepend on these marginal characteristics.     

Lp估计理论及应用

基于最小二乘（ＬＳ）估计对粗差或长尾分布甚为敏感，作者提出用一簇估计－Ｌｐ估计似改善之。本文主要论述了Ｌｐ估计的基本原理及修正残差法的计算，并对Ｌｐ估计的抗差性能力及效率与ｐ的关系进行了分析，最后用一算例进行了讨论。     

子波估计及极大似然反褶积方法稳健性讨论

利用极大似然反褶积提取鲁棒性地震子波的方法进行了研究，并讨论了极大似然反褶积的稳健性。理论分析表明，在理想条件下极大似然反褶积是无偏估计，而且还是一致估计，这一结论可以由所提取的地震子波得到验证。实际地震资料的处理结果分析表明，极大似然反褶积具有很好的稳健性。应当指出，为保证地震子波的鲁棒性，极大似然反褶积子渡时窗应尽量满足统计条件，以提高极大似然反褶积的稳健性。     

数字水印及其鲁棒性研究

水印在数字作品的版权深护上具有无可替代的特昧优势，已成为网络数字作品版权保护的主要工具之一。文中介绍数字水印的特点及其在数字地图怍品版权保护中的应用，并对其鲁棒性问题进行了初步研究；最后介绍了配合水印应用研究进行的软件开发和实验结果。     

Design of multiple tuned mass dampers by using a numerical optimizer

A new method to design multiple tuned mass dampers (multiple TMDs) for minimizing excessive vibration of structures has been developed using a numerical optimizer. It is a very powerful method by which a large number of design variables can be effectively handled without imposing any restriction before the analysis. Its framework is highly flexible and can be easily extended to general structures with different combinations of loading conditions and target controlled quantities. The method has been used to design multiple TMDs for SDOF structures subjected to wide‐band excitation. Some novel results have been obtained. To reduce displacement response of the structure, the optimally designed multiple TMDs have distributed natural frequencies and distinct damping ratios at low damping level. The obtained optimal configuration of TMDs was different from the earlier analytical solutions and was proved to be the most effective. A robustness design of multiple TMDs has also been presented. Robustness is defined as the ability of TMDs to function properly despite the presence of uncertainties in the parameters of the system. Numerical examples of minimizing acceleration structural response have been given where the system parameters are uncertain and are modeled as independent normal variates. It was found that, in case of uncertainties in the structural properties, increasing the TMD damping ratios along with expanding the TMD frequency range make the system more robust. Meanwhile, if TMD parameters themselves are uncertain, it is necessary to design TMDs for higher damping ratios and a narrower frequency range. Copyright © 2004 John Wiley & Sons, Ltd.     

地震预报中震级-时间模型的应用

本文从震级-时间模型的表达式出发,讨论了模型参数所含的物理意义,通过计算中国大陆各地震带的震级-时间模型参数,认为只有其中11条地震带的强震孕震过程可以用该模型来表达,其平均参数为b=0.383,c=0.154,d=0.035,B=0.844,C=-0.209,D=0.188。通过变换资料的震级下限、时间域和空间域的计算结果,讨论了模型参数的鲁棒性。通过对模型应用空间范围的分析,在华北地震区,在利用震级—时间模型对未来的地震危险进行预测时,计算单元应不小于4°×4°,而在西北和西南地区,计算单元不要小于3°×3°。而通过对模型应用时间范围的分析,在应用模型进行预测时,资料时间域要尽量长一些。