参数点估计的无偏性

在总体为二项分布下,讨论参数点估计的无偏性,得出了无偏估计不一定存在、不唯一的结论。     

“数值分析”中实践教学的探讨

本文阐述了在数值分析教学中加入实践环节的越要性,并通过具体实例介绍了作者在数值分析中进行实践教学的尝试,旨在对今后的教学起到一定的促进作用。     

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.     

Science Letters: On numerical calculation in symplectic approach for elasticity problems

The symplectic approach proposed and developed by Zhong et al. in 1990s for elasticity problems is a rational analytical method, in which ample experience is not needed as in the conventional semi-inverse method. In the symplectic space, elasticity problems can be solved using the method of separation of variables along with the eigenfunction expansion technique, as in traditional Fourier analysis. The eigensolutions include those corresponding to zero and nonzero eigenvalues. The latter group can be further divided into α-and β-sets. This paper reformulates the form of β-set eigensolutions to achieve the stability of numerical calculation, which is very important to obtain accurate results within the symplectic frame. An example is finally given and numerical results are compared and discussed.     

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.     

Protein nanotechnology — A powerful futuristic diagnostic technique

Healthcare can be maintained well, when diagnosis is quick, accurate, cost-effective and painless. DNA and RNA based diagnosis may not reveal the right information for certain diseases. Identification and quantification of proteins and their folding mechanism are very important in diagnosis of diseases. Small quantities of proteins, which generally escape from detection and are responsible for the diseases, now can be quantified by protein nanotechniques which aids in the diagnosis. In this review, we have summarized the recent developments in nanotechnologies such as protein microarrays, biosensors etc. and their application in diagnosis of diseases at proteomics level have also been discussed.     

基于核密度估计聚类和关联规则的医学图像分类

基于数据挖掘的医学图像分类方法研究是多媒体数据挖掘的一个重要组成部分。在分析和总结了现有各种特征提取方法的基础上，提出了基于核密度估计聚类和关联规则的医学图像分类算法和关联规则的医学图像分类器框架。该算法先用核密度估计的聚类算法实现医学图像的聚类，在聚类的结果上提取局部特征，在局部特征上用关联规则实现医学图像的分类。实验结果表明可以较好的提高医学图像分类的准确率。     

含持久生存数据模型的识别问题

混合和非混合模型被广泛地用于拟合含有持久生存者的生存数据．当添加有协变量时,这两类模型却都不具有比例危险率(PH)结构．“不正确”比例危险率模型能克服上述缺点．本文研究此模型的识别问题．同时也考虑“不正确”的可加危险率(AH)模型的识别问题．本文的结果对模型的参数估计有重要意义．     

从PISA到“面向未来”科学素养调查

PISA的评估具有前瞻性,它的焦点不在于评估学生对学校课程的掌握程度,而是着眼于真实生活的挑战。与PISA的评估重点有类似的精神实质,新课程也要求将学生科学素养发展的焦点从“知道什么”向“能做什么”转变。“面向未来”科学素养调查借鉴PISA的思路和方法,探索性地建立了评估科学素养发展的五能力模型和情景化测试的方法。调查的实践成功地描述了学生发展的现状,找到了问题所在,对科学教育提供了有价值的建议。调查证明,以“面向未来”为价值导向,以“能力”为评估对象,是评估学生科学素养发展和科学课程改革的可操作、有成效的评估方案。     

广义根方估计的效率

讨论了线性回归模型中未知参数最小二乘估计的改进,引入了一种估计的相对效率,证明了广义根方估计比狭义根方估计的效率较高。