Studies of Mental “Noise”

Successive tests of subjects' performance in reaction time tasks were treated as time series and submitted to spectrum analysis. Rather than revealing the white noise expected by the view that variability is due to random error (equivalent power across frequency), the power spectra revealed colored noise. The slopes of the power spectra did not vary much for tasks differing in memory requirements. Spectrum analysis of time series from the logistic map also showed colored noise in regions on the edge of chaos, showing that the presence of colored noise in cognitive data need not oblige a theoretical account based on a complex, high-dimensional, system.     

LIF技术测量浓度场的影响因素分析

本文研究了作为示踪剂的荧光素钠的谱图，测定了荧光素钠在蒸馏水和普通自来水中的吸光系数，估算了荧光分子的平均寿命。最后，详细分析了浓度、激光功率、温度、ｐＨ值和截止滤光片对荧光强度的影响。     

大变位时物体变形测量的相关性恢复方法

本文提出根据白光散斑图像数据模拟刚体位移复位的相关性恢复方法，以解决物体大变位情况下的变形测量问题     

基于光学和扫描显微平台的微尺度实验力学检测技术和装置研究

本文基于光学和扫描显微平台,介绍了本研究组在微尺度实验力学检测技术和设备方面的最新研究成果。在检测技术方面涉及显微散斑干涉技术、微标记阵列检测技术、晶粒变形分析技术、光学探针动静态变形分析技术;在检测系统和装置方面介绍了新近开发的双视场薄膜检测系统、散斑微干涉系统、微标记检测平台、AFM和SEM单轴拉伸装置、三维微定位与加载系统、微力传感器及其标定装置、微动平台驱动装置等。探讨了微尺度实验力学检测中的问题和新的检测技术,给出了一些典型的应用和相关装置。     

两相流显微PIV/PTV系统的开发

开发了一个能同时测量两相流中两相速度和细颗粒尺寸分布的显微PIV/PTV系统,其硬件系统包括大功率连续激光器、显微镜、高速摄像机;软件系统由改进的球形颗粒图像识别算法、各种图像处理算法和各种先进的PIV/PTV算法组成。其中改进的圆弧识别算法能够进行更准确地进行曲线分割而能对充满噪音并相互重叠的颗粒图像给出较好的识别结果。应用该PIV系统,可以在微秒和微米数量级上捕获细颗粒/气泡图像,并能较准确地同时得到两相速度、颗粒尺寸和浓度分布。对焚香可吸入颗粒物进行了速度和尺寸的同时测量,得到了较满意的结果。     

高精度光纤陀螺的分辨率测量

系统介绍了在单轴转台上测量高精度光纤陀螺分辨率的方法。该方法以GJB2426—95对光纤陀螺分辨率的定义为依据，以地球自转水平分量的余弦分量为陀螺的输入量，提出了一种正交三点寻北法。分析了光纤陀螺输出信号的特征，提出用对称测量法消除陀螺零偏并减小零漂对测量的影响。最后用IEEE推荐的测量不确定度评定方法对测量结果的不确定度进行了严格的评定。     

The estimate and measurement of longitudinal wave intensity

Quasi-longitudinal waves are one type of structural waves, which are important at high frequencies. This paper studies the estimate theory and measurement technique of quasi-longitudinal waves, analyzes the bias error due to the effect of bending waves. In a two-dimensional quasi-longitudinal wave field, the intensity vector is the sum of the effective intensity vector and the intensity variation vector. Its axial component is proportional to two imaginary parts of cross spectral densities and in the measurement, it is measured by a pair of two-transducer arrays. In a onedimensional quasi-longitudinal wave field, the intensity variation is zero, the intensity is proportional to only one imaginary part of a cross spectral density and it can be measured using a two-transducer array. If bending and quasi-longitudinal waves coexist and the contribution from bending waves cannot be eliminated or reduced to a certain extent, the measured quasi-longitudinal wave intensity will contain a large error. The results measured on the three-beam structure show that quasi-longitudinal wave intensity can be accurately measured using the intensity technique when bending waves are negligible in comparison with quasi-longitudinal waves. The project supported by the National Natural Science Foundation of China     

用LDV系统测量转盘萃取塔内流场

本文应用激光多普勒测速仪对二种转盘萃取塔模型进行切向速度、轴向速度和湍流度测量。实验结果表明，在ＲＤＣ是切向速度比较大，因而有较大的搅拌效果，它的内部流场比较均匀稳定，有利于传质，所以ＲＤＣ是广泛应用于化学工业中的一种液－液萃取设备。     

A new interferometric method for vibration measurement by electronic holography

Electronic holography is a well-established technique used in real-time, non-contact, whole-field displacement measurements. When using the real-time, time-averaged method for vibration measurments, the quantitative interpretation of dense fringe patterns is difficult because of speckle noise. Even when speckle-reducing procedures are used, such as multiple-frame averaging or rotation of the illumination beam, the remaining speckles and decreasing visibility of higher-order Bessel fringes are serious limitations. The primary objective of this paper is to present a new realtime, interferometric method for mechanical vibration measurements and the associated quantitative interpretation. The fringe pattern obtained by this method is quasi-binary and half as dense as in the time-averaged method. The method greatly improves the overall visibility (contrast, resolution) of vibration fringe patterns without any sacrifice in the real-time capabilities. Quantitative fringe interpretation is straightforward and based on binary fringe tracking. It allows quantitative measurements in situations where the time-averaged fringe processing fails.     

Full-field speckle pattern image correlation with B-Spline deformation function

A full-field speckle pattern image correlation method is presented that will determine directly the complete, two-dimensional deformation field during the image correlation process on digital images obtained using computer vision systems. In this work, a B-Spline function is used to represent the object deformation field throughout the entire image area. This is an improvement over subset-based image correlation methods by implicitly maintaining position and derivative continuity constraints among subsets up to a specified order. The control point variables within the B-Spline deformation function are optimized iteratively with the Levenberg-Marquardt method to achieve minimum disparity between the predicted and actual deformed images. Results have shown that the proposed method is computationally efficient, accurate and robust. The general framework of this method can be applied ton-dimensional image correlation systems that solve for multi-dimension vector fields.