The population-sample decomposition approach to multivariate estimation methods

In this paper it is argued that all multivariate estimation methods, such as OLS regression, simultaneous linear equations systems and, more widely, what are known as LISREL methods, have merit as geometric approximation methods, even if the observations are not drawn from a multivariate normal parent distribution and consequently cannot be viewed as ML estimators. It is shown that for large samples the asymptotical distribution of any estimator, being a totally differentiable covariance function, may be assessed by the δ method. Finally, we stress that the design of the sample and a priori knowledge about the parent distribution may be incorporated to obtain more specific results. It turns out that some fairly traditional assumptions, such as assuming some variables to be non-random, fixed over repeated samples, or the existence of a parent normal distribution, may have dramatic effects on the assessment of standard deviations and confidence bounds, if such assumptions are not realistic. The method elaborated by us does not make use of such assumptions.     

Analysis of a particle method for the one‐dimensional Vlasov‐Maxwell system

In this article we present a particle method for solving numerically the one‐dimensional Vlasov‐Maxwell equations. This method is based on the formulation by characteristics. We perform the error analysis and we investigate the properties of this scheme. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009     

Melting of PbBr2: A DSC investigation

The melting of PbBr₂ in sealed crucibles was investigated by means of DSC. Three factors were considered to affect melting point: i) impurities, ii) the bromine pressure over the PbBr₂, and iii) photolysis. Both crystals and powders were investigated. The peak of the melting changed after sample grinding. The bromine pressure over the PbBr₂ was found to cause a significant error in the determination of the melting point.Lead bromide melts at 370.6±0.2°C. The heat of melting is 42.9±1.8 J g^–1.This revised version was published online in November 2005 with corrections to the Cover Date.     

低层大气误差对距离变化率折射误差的影响

大气折射残差模型是综合处理雷达测量数据及光学测量数据时需要重点考虑的残差项。本文对现行的大气折射差模型提出了质疑，并从折射原理出发，在球面分层的情况下重新推导了大气折射指数的变化对视在距离变化率与真实距离变化率之差的影响。     

非参数可修系统可用度的评定

考虑可修的串联系统,其单元产品在出现故障时,由于种种原因,故障不能得到及时维修,形成了一段保障延误时间.于是这一更新过程为:正常工作(直到出现故障)-保障延误-故障维修-正常工作…….假设每一时段的分布未知,且相互独立,给出了可用度的点估计和置信下限.     

基于神经网络的感应电机转速估计方法

根据神经网络能够任意逼近非线性函数的功能，针对感应电机这样一个时变的非线性系统，提出了一种利用神经网络估算感应电机转速的模型，仿真结果表明，这种神经网络转速估算模型可以准确地跟踪感应电机转速的变化，具有良好的动态跟随性能。     

频率选择性衰落信道中的频偏盲估计

根据频率选择性衰落信道的抽头延迟线模型,将针对平坦衰落信道的CS(周期平稳过程理论)频偏盲估计算法扩展到了频率选择性衰落信道,并通过仿真证明这种扩展是可行的.仿真结果还表明CS算法不仅有好的抗平坦衰落能力,而且有很好的抗频率选择性衰落性能.     

确定信号情况下矢量水听器检测及估计性能研究

在某些场合,例如水下定位、编码通信,信号具有确知脉冲信号特性,声源相对于接收器的方位,可以采用矢量水听器处理来获得。对于确知脉冲信号,本文证明了在各向同性噪声场下,参考声压和振速的相关处理器的方向是声源方位的最大似然方位估计,以及方位估计的克拉美-罗界CRB(Cramer-Rao Bound)。给出了计算机的仿真结果。     

A HIGH RESOLUTION TIME DELAY ESTIMATION BASED ON THE MAXIMUM ENTROPY POWER SPECTRUM ESTIMATON

Multipath time delay estimation is constrained by the width of the signal correlation function when using correlation based methods. This paper obtains a high resolution time delay estimation by introducing Burg algorithm and Marple algorithm of the maximum entropy power spectral estimation to non-resolvable multipath time delay estimatoin. The principles, the performaces and the results of computer simulation are given.     

权马尔可夫链在人口死亡率时序误差预测中的应用

针对人口死亡率时间序列既有摆动又有一定趋势的特点,首先对人口死亡率的时间趋势项进行拟合,然后对人口死亡率的误差序列进行分析,提出了以规范化的自相关系数为权,用加权的马尔可夫链来预测人口死亡率状况。并通过实例对该方法进行了具体的应用。