RKPM方法关于非线性椭圆边值问题的的误差估计

通过重构核近似的基本原理简单介绍了重构核质点法(reproducing kernel particle meshfree methods,RKPM),关于非线性椭圆方程的Dirichlet问题,结合重构核近似的理论误差估计,研究了在满足一定条件下的RKPM法对于该类问题的解的误差估计.     

二次损失下方差分量模型中回归系数的线性Minimax估计

考虑方差分量模型,对任一可估函数,在二次损失下得到了线性可估函数在齐次估计类中的唯一的线性Minimax估计.     

基于Copula函数的中国人口总量与GDP总量相关性研究

基于Copula函数,依据1978～2004年度人口总量与GDP总量数据,构建了反映中国人口总量与GDP总量相关性的较为理想的模型。应用非参数估计给出了中国人口总量与GDP总量的Copula函数及Kendall’τ的合理估计。模型揭示中国人口总量与GDP总量之间的Kendall’τ为0．8571．     

基于分布估计的多目标量子进化算法

基于NSGAⅡ框架,利用QEA的机制来保持多样性,同时引入分布估计二进制个体加快搜索的效率,本文提出了一个由量子计算启发的多目标演化算法(MOEA)--基于分布估计的多目标量子演化算法(记为EQMEA).通过实例验证,EQMEA可以找到更接近与最优前沿的解,且解的分布更均匀.     

Application of honey-bee mating optimization on state estimation of a power distribution system including distributed generators

We present a new approach based on honey-bee mating optimization to estimate the state variables in distribution networks including distributed generators. The proposed method considers practical models of electrical equipments such as static var compensators, voltage regulators, and under-load tap changer transformers, which have usually nonlinear and discrete characteristics. The feasibility of the proposed approach is demonstrated by comparison with the methods based on neural networks, ant colony optimization, and genetic algorithms for two test systems, a network with 34-bus radial test feeders and a realistic 80-bus 20 kV network.     

Time-domain training sequences design for MIMO OFDM channel estimation

This paper describes a Least Squares （LS） channel estimation scheme for MIMO OFDM systems based on time-domain training sequence. We first compute the minimum mean square error （MSE） of the LS channel estimation, and then derive the optimal criteria of the training sequence with respect to the minimum MSE. It is shown that optimal time-domain training sequence should satisfy two criteria. First, the autocorrelation of the sequence transmitted from the same antenna is an impulse function in a region longer than the channel maximum delay. Second, the cross-correlation between sequences transmitted from different antennas is zero in this region. Simulation results show that the estimator using optimal time-domain training sequences has better performance than that using optimal frequency training sequence at low signal-to-noise ratio （SNR）. To reduce the training overhead, a suboptimal training sequence is also proposed. Comparing with optimal training sequence, it has low computation complexity and high transmission efficiency at the expense of little performance degradation.     

Optimal waveband identification for estimation of leaf area index of paddy rice

The objectives of the study were to select suitable wavebands for rice leaf area index (LAI) estimation using the data acquired over a whole growing season, and to test the efficiency of the selected wavebands by comparing them with feature positions of rice canopy spectra. In this study, the field experiment in 2002 growing season was conducted at the experimental farm of Zhejiang University, Hangzhou, China. Measurements of hyperspectral reflectance (350-2500 nm) and corresponding LAI were made for a paddy rice canopy throughout the growing season. And three methods were employed to identify the optimal wavebands for paddy rice LAI estimation: correlation coefficient-based method, vegetation index-based method, and stepwise regression method. This research selected 15 wavebands in the region of 350-2500 nm, which appeared to be the optimal wavebands for the paddy rice LAI estimation. Of the selected wavebands, the most frequently occurring wavebands were centered around 554, 675, 723, and 1633 nm. They were followed by 444, 524, 576, 594, 804, 849, 974, 1074, 1219, 1510, and 2194 nm. Most of them made physical sense and had their counterparts in spectral known feature positions, which indicates the promising potential of the 15 selected wavebands for the retrieval of paddy rice LAI.     

聚焦中考“估计”试题

数学新课程标准中强调要发展学生的数感、符号感、空间观念、统计观念以及应用意识与推理能力．数感主要表现在：理解数的意义;能用多种方法来表示数;能在具体的情境中把握数的相对大小关系;能用数来表达和交流信息;能为解决问题而选择适当的算法;能估计运算的结果,并对结果的合理性作出解释．“估计”试题是新课程改革中出现的一类新颖问题．     

推广增长曲线模型中最小二乘估计的相对效率

对于推广增长曲线模型,本文先是给出了回归系数最小二乘估计和最佳线性无偏估计的明晰表达式;然后进一步研究了最小二乘估计的相对效率,得到了最小二乘估计相对效率的下界.     

精读课应重视读前阶段教学

长期以来，精读课教学着重强调阅读过程本身词法、句法层次上的掌握与理解以及读后阶段的讨论与各类辅助练习；而对读前阶段没有给予足够的重视。读前阶段教学通过背景知识的提供，可以引发学生的阅读兴趣、开发学生的已有知识并能刺激学生的思维，从而使学生的先验图式和语篇自然衔接，以更有效地达到阅读的预期目的