Pseudo-Stokes Vector Correlation From Complex Signal Representation of a Speckle Pattern and Its Applications to Micro-Displacement Measurement

Abstract:  As an improvement of the intensity correlation used widely in conventional electronic speckle photography, we propose a new technique for displacement measurement based on correlating Stokes-like parameters derivatives for transformed speckle patterns. The method is based on a Riesz transform of the intensity speckle pattern, which converts the original real-valued signal into a complex signal. In closest analogy to the polarisation of a vector wave, the Stokes-like vector constructed from the spatial derivative of the generated complex signal has been applied for correlation. Experimental results are presented that demonstrate the validity and advantage of the proposed pseudo-Stokes vector correlation technique over conventional intensity correlation technique.     

基于优化FBD算法的谐波与闪变综合抑制装置的应用与研究

根据当前电网中存在的实际问题,提出对系统进行谐波与闪变综合抑制的必要性.对传统的FBD(Fryze-Buchholz-Dpenbrock)法进行分析和改进.在此基础上针对三相四线制系统对FBD法进行了优化设计,通过增加一个反馈回路,提高了检测方法的实时性,增强了谐波与闪变抑制装置的动态响应特性.在理论研究与仿真分析的基础上,搭建了基于并联型有源电力滤波器的谐波与闪变综合抑制装置的仿真与实验模型,检测算法采用FBD优化算法,电流跟踪控制电路采用基于滞环比较的空间矢量控制策略.仿真与实验效果验证了检测算法与控制策略的有效性和准确性.     

渐进还是激进——经济转轨道路的思索

计划经济向市场经济的转型是过去十年间最主要的经济事件。在这次巨变中,中国选择了一条与中东欧国家和前苏联截然不同的道路,"摸着石头过河"的渐进式改革。不同的改革方式导致了不同的改革结果。中国经历了20年的迅速增长,而俄罗斯和其他独联体国家却经历了将近10年的下降。中国和中东欧国家经济转型的实践对传统经济理论提出了挑战,也把世界各国经济学家的研究焦点从标准的价格与货币理论转向合同及其社会制度环境。     

移动融冰装置在RTDS上的仿真试验研究

西安整流器公司"KYAF-1200/14000直流移动融冰电源"进行了不同运行工况的RTDS实时仿真试验,对融冰线路耦合感应、投低压补偿电容、融冰装置正常启动过程的谐波等进行了试验分析,根据仿真试验.提出了有效的融冰运行方式的建议,以提高融冰装置运行的安全性和稳定性.     

自适应Kalman滤波器在水下被动目标跟踪中的应用

在水下被动目标跟踪系统中，直角坐标系下的扩展卡尔曼滤波器容易发散而导致滤波精度很差，提出了一种修正极坐标系下的自适应卡尔曼滤波算法，对虚拟噪声进行估计，动态补偿模型线性化误差，消减系统的观测误差．对其滤波理论及算法进行了研究和仿真。仿真结果表明，该算法提高了滤波的稳定性、快速性和精确性，优于一般的扩展卡尔曼滤波算法。     

三电平逆变器SHEPWM多组解特性比较及实验

研究了应用于三电平NPC逆变器的特定消谐(Selective Harmonic Eliminated PWM, SHEPWM)技术.传统SHE均假设波形1/4周期对称,这有助于减小方程组的维数,但同时也减少了可行解的空间,而消除低次谐波并不严格要求波形1/4周期对称.针对1/4周期对称SHE,以N=7为例给出四组解,然后进一步研究1/2周期对称下的解,从理论上证明可以存在无数组解,进一步将其分为两种不同的类型.分析和比较了1/4周期对称解和1/2周期对称解的区别和联系,以及不同类型的解在谐波特性方面的差异,并通过实验进行了验证.     

无功、负序及谐波电流检测中的数字滤波器研究

数字滤波器是基于瞬时无功理论的无功、负序及谐波电流检测中一个重要部分,其精度和速度直接影响检测的结果。文中在各种电压和电流情况下对电流检测中所需要的数字滤波器进行分析,得出数字滤波器分类设计的想法,并优化设计出三种适用于不同电压和电流情况的数字滤波器。仿真和实验结果证明所设计的数字滤波器与目前电流检测中使用的数字滤波器相比,在保证精度的同时能有效提高速度,且本身算法的复杂性并未显著增加。     

THEORETICAL ANALYSIS OF COORDINATES MEASUREMENT BY FLEXIBLE 3D MEASURING SYSTEM

The system mathematical model of flexible 3D measuring system is built by theoretical analysis,and the theoretical formula for measuring space point coordinate is also derived. Frog-jumping based coordinate transform method is put forward in order to solve measuring problem for large size parts. The frog-jumping method is discussed,and the coordinate transform mathematical model is method of the space point coordinate compared to original value,and an advanced method is provided. Form the space point coordinate transform formula can derive the calculation measuring method for measuring large size parts.     

A signal theory approach to the space and frequency variant filtering performed by the human visual system

A mathematical representation is given of the processing performed by the peripheral nervous cells of the human visual system. This representation consists essentially of a set of shift-variant convolutions, implying non-uniform resolutions in both the space and frequency domains. A remarkable property of such “convolutions” is the form-invariance of their outputs with respect to (size) linear scalings of the inputs. It is shown that this latter property is a necessary support of the hypothesis according to which the visual system translates linear scalings of the (retinal) inputs into shifts of the (cortical) outputs.