一种按时间切换的最速控制方法

基于初始状态空间下的子空间概念，提出了一种按时间进行切换的最速控制方法，不需要求取开关线或开关面。数字仿真结果表明，采用这一方法是完全可行的。     

Autoregressive modelling in vector spaces: An application to narrow-bandwidth spectral estimation

A generalisation of the Burg algorithm to vector spaces is described. This can be used to subsample time series that have narrow frequency bandwidth, thereby reducing the computation time and the complexity of the autoregressive model required. The technique is preferable to conventional subsampling.     

Liquid Crystal Television Spatial Light Modulator

The liquid crystal televison spatia light modulator(LCTVSLM)characterized is usable in optical processing applications.e.g.,optical pattern recognition,associative memory,optical computing,correlation detection and optical data processing systems.The array performance and real-time optical correlation applications are reviewed.     

光学活性物质的工业生产方法

本文介绍了光学８活性牺牲垢几种工业规模的生产方法及最新的进展，分析了各种方法的特点及存在的问题。     

On the application of CAD technology for the synthesis of spatial revolute–revolute dyads

This work presents a method based on Computer Aided Design or CAD for facilitating the synthesis of Revolute–Revolute (R–R) dyads with adjustable moving pivots. The CAD-based method presented in this work ensures that all prescribed rigid-body parameters used to synthesize the R–R dyad satisfy particular kinematic requirements of an R–R dyad. Through the application of this CAD method, five of the six general R–R dyad constraint equations are satisfied and therefore not essential for the synthesis of the R–R dyad. By reducing the number of dyad design constraints from six to one, the user can synthesize R–R links with adjustable moving pivots for multi-phase motion and path generation applications. The example included demonstrates the use of the CAD method in the synthesis of an RRSS path generator with adjustable moving pivots.     

SQL extension for spatio-temporal data

An SQL extension is formalized for the management of spatio-temporal data, i.e. of spatial data that evolves with respect to time. The extension is dedicated to applications such as topography, cartography, and cadastral systems, hence it considers discrete changes both in space and in time. It is based on the rigid formalization of data types and of SQL constructs. Data types are defined in terms of time and spatial quanta. The SQL constructs are defined in terms of a kernel of few relational algebra operations, composed of the well-known operations of the 1NF model and of two more, Unfold and Fold. In conjunction with previous work, it enables the uniform management of 1NF structures that may contain not only spatio-temporal but also either purely temporal or purely spatial or conventional data. The syntax and semantics of the extension is fully consistent with the {SQL:2003} standard.     

分数阶Fourier域多分量LFM信号间的分辨研究

在分数阶Fourier域内,当多分量线性调频(LFM)信号的初始频率和调频率相近时,信号的尖峰会出现无法分辨的现象,导致目标信号漏检.文中分析了LFM信号在分数阶Fourier域的频谱分布特征,以及离散分数阶Fourier变换计算条件下LFM信号的频谱分布特征.推导了两个LFM信号在分数阶Fourier域的临界分辨距离,以及两个LFM信号尖峰之间的距离与量纲归一化因子的变化关系,发现选择合理的量纲归一化因子可以增大两个信号尖峰之间的距离.文中提出一种量纲归一化因子优化选择的方法,该方法可以提高分数阶Fourier变换对多分量LFM信号的分辨能力.最后,仿真结果验证了该方法的有效性.     

Research on resolution between multi-component LFM signals in the fractional Fourier domain

When the initial frequencies and chirp rates of multi-component linear frequency modulation (LFM or chirp) signals are close,the signals may not be distinguished in the fractional Fourier domain (FRFD).Consequently,some signals cannot be detected.In this paper,first,the spectral distribution characteristics of a continuous LFM signal in the FRFD are analyzed,and then the spectral distribution characteristics of a LFM signal in the discrete FRFD are analyzed.Second,the critical resolution distance between the peaks of two LFM signals in the FRFD is deduced,and the relationship between the dimensional normalization parameter and the distance between two LFM signals in the FRFD is also deduced.It is discovered that selecting a proper dimensional normalization parameter can increase the distance.Finally,a method to select the parameter is proposed,which can improve the resolution ability of the fractional Fourier transform (FRFT).Its effectiveness is verified by simulation results.     

空间数据库中栅格元数据管理模型的设计与实现

分析了栅格元数据基于文件、关系表和XML的3种存储管理方式,比较它们的优缺点,得出了XML适合描述空间数据库中栅格元数据的层次性、复杂性和面向对象性,并具有可扩展性。在BeyonDB中设计和实现了基于XML的栅格元数据管理模型,并以地球系统科学数据共享平台中DEM数据集为例验证该模型的可扩展性,为空间数据库中海量遥感影像数据的管理研究提供参考。     

基于地统计方法的二氧化碳浓度空间插值研究

克里格法（Kriging）是地质统计学的主要内容之一,从统计意义上说,是从变量关系和变异性出发,在有限区域内对区域化变量的取值进行无偏、最优估计的一种方法：从插值角度讲是对空间分布的数据求线性最优、无偏内插估计的一种方法。克里格法的适用条件是区域化变量存在空间相关性。将临安市内的二氧化碳作为区域化变量．根据不同的半变异函数理论模型,采用普通Kriging法,通过对比分析得到：基于地统计的插值方法。根据半变异函数云图和试验方差最小的原理．选择合适的半变异函数理论模型进行变量的空间插值．能够较好地模拟区域化变量的空间连续分布格局．并取得较好效果。