冷变形和时效温度对扭振时恒弹性合金f_s-T曲线的影响

本文探讨Fe-Ni-Cr-Ti合金在冷变形和时效状态中两种振动模式(扭振和横振)中的f(共振频率)-T(温度)曲线,以及冷变形压下量和时效温度对扭振模式中f_s(扭振共振频率)-T曲线的影响,指出:在冷变形状态的两种振动模式中,其f-T曲线相似但不重合;时效状态时扭振模式中的f_s-T曲线极大值与横振模式中的f_l(横振共振频率)-T曲线极小值所对应的温度移至室温附近,同一材料,随着时效温度升高,在扭振模式下其频率温度系数由正变负,在横振模式下由负变正,扭振模式下,随着冷变形压下量增加或时效温度降低,f_s-T曲线极大值移向高温,可通过调整冷变形压下量和时效温度以控制极大值对应温度,获得较低的频率温度系数值。     

一种加快最小二乘参数估计的参数跟踪速度的措施

本文探讨了如何加快最小二乘参数估计的参数跟踪速度问题。为此目的提出了一种自动调整其“遗忘因子”值的措施。仿真计算的结果证实,所采取的这种措施是可行而且是有效的。     

关于有限集点分布均匀性的度量方法

有限点均匀性的度量方法目前尚无一致公认的标准．本文讨论用偏差来度量点集均匀性的偏向性，进而讨论用其它方法度量均匀性的可行性     

多面结构连接的有限元网格划分

以船体结构中一典型多面板连接结构为例,阐述了利用有限元分析预处理软件先建立几何模型,利用区域分割法将几何模型进行区域划分,最后进行网格自动划分和调整,形成有限元网格模型的完整过程,研究为同类模型的建立提供了简便的思路,有效减少了建模的出错率。     

Matrix equation and its application to classification of finite-dimensional estimation algebras

Under a very natural condition, a matrix equation is proved to have only trivial solution. This result is then applied to the classification problem of finite-dimensional estimation algebras, which gives a simpler proof of Tang s recent result on the constant structure of the O~matrix.     

声光通讯实验的改进

利用光纤完成声光通讯实验的方法，与原有的实验方法相比，改进后的实验具有操作方便、灵活和易于实现的特点。     

Target estimation using MIMO radar with multiple subcarriers

This paper analyzes the effect of waveform parameters on the joint target location and velocity estimation by a noncoherent multiple input multiple output (MIMO) radar transmitting multiple subcarriers signals. How the number of subcarriers influences the estimation accuracy is illustrated by considering the joint Cramer-Rao bound and the mean square error of the maximum likelihood estimate. The non-coherent MIMO radar ambiguity function with multiple subcarriers is developed and investigated by changing the number of subcarriers, the pulse width and the frequency spacing between adjacent subcarriers. The numerical results show that more subcarriers mean more accurate estimates, higher localization resolution, and larger pulse width results in a worse performance of target location estimation, while the frequency spacing affects target location estimation little.     

一种适用于高阶QAM载波恢复的改进型稳定性算法

本文提出了一种结合频率相位载波恢复的数字QAM接收系统，将非零均值引入到Stop—and—Go控制器中，有效地解决了稳定状态的误差偏移较大的问题。仿真结果表明系统在15dB信噪比时，采用载波恢复电路只需7500个符号周期即可捕获达到6％符号率的频偏和30。的相偏，同时其稳态相位抖动亦显著减少到0．07。     

Forecasting time series with increasing seasonal variation

Four options for modeling and forecasting time series data containing increasing seasonal variation are discussed, including data transformations, double seasonal difference models and two kinds of transfer function-type ARIMA models employing seasonal dummy variables. An explanation is given for the typical ARIMA model identification analysis failing to identify double seasonal difference models for this kind of data. A logical process of selecting one option for a particular case is outlined, focusing on issues of linear versus non-linear increasing seasonal variation, and the level of stochastic versus deterministic behavior in a time series. Example models for the various options are presented for six time series, with point forecast and interval forecast comparisons. Interval forecasts from data-transformation models are found to generally be too wide and sometimes illogical in the dependence of their width on the point forecast level. Suspicion that maximum likelihood estimation of ARIMA models leads to excessive indications of unit roots in seasonal moving-average operators is reported.     

基于人类视觉系统的物体提取方案

提出了一种物体提取方案，根据人类视觉系统（ＨＶＳ）具有形状和运动两个并行通道的特点以及两者交互作用的原理，采用相对简单的图像分割和运动分割技术，将两者结合在一起，来增强对运动物体的分割处理