New method for reactive power and energy measurement

The properties of an electronic reactive power and energy measurement method based on a frequency-controlled power-to-pulse-rate conversion are analyzed. The reactive power and energy measurements can be efficiently performed by using a simple integrating circuit as a phase shifter, and frequency-controlled analog-to-pulse-rate converter. A low value of the output pulse rate should not be considered as an inherent disadvantage of the method. By introducing a phase-locked loop in order to achieve high pulse-rate output, the benefit of high resolution is added to the method. The improved electronic structure for the measurement can be implemented in the design of reactive power and energy standards. For precision var-hour meters based on the proposed method, it is possible to have an efficient error-checking and adjustment procedure. The proposed method allows reactive power and energy measurement to be made in single- and poly-phase, symmetrical and unsymmetrical, and balanced and unbalanced networks     

由序列图像进行三维测量的新方法

目前的三维测量方法都需要专门的测量设备且存在着种种限制,为此提出了一种基于图像序列进行三维测量的新方法。将由数码相机围绕被测物体拍摄的多幅图像导入计算机,利用图像处理知识得到特征的二维信息;采用计算机视觉方法,对特征从射影空间到欧式空间分层逐步重建即可完成三维测量。设计一套特征标志组合,作为辅助测量工具避免了特征匹配难题。确立了一套图像分割与识别策略获得特征标志二维信息,识别率可达到95%以上。采用基于模约束的摄像机分层自标定方法得到特征在欧式空间下的三维信息,并通过多种优化方法减少误差的影响。该方法在硬件上实现简单,对测量条件要求不高。实际试验表明,相对误差可达到1.48%,重投影误差为0.3864像素。     

New method for routine measurement of coercivity in magnetic bubble films

We describe a new technique for measuring coercivity in magnetic bubble films which consists of placing the film in a weak field gradient (∼1 Oe./μm) in order to obtain a set of finger-like domains. The unconstrained ends of these domains are caused to move back and forth in response to an oscillatory field, and the coercivity is obtained from an extrapolation of the linear portion of the response vs. drive field curve. We present a comparison between coercivity values in materials with 3μm and 1.7μm stripe-widths obtained using the new technique and bubble translation. Good correlation is observed for both types of material, the values obtained with the new technique being somewhat higher than the bubble translation values. The difference is ascribed to material non-uniformities.     

Variogram-based method for contrast measurement

We present a technique for determining the contrast of an intensity distribution in the presence of additive noise and other effects, such as undesired local amplitude or offset variations. The method is based on the variogram function. It just requires the measurement of the variogram at only four points and, as a consequence, it is very fast. The proposed technique is compared with other standard techniques, showing a reduction in the error of the contrast measurement.     

Histogram-based method for contrast measurement

A histogram-based technique for robust contrast measurement is proposed. The method is based on fitting the histogram of the measured image to the histogram of a model function, and it can be used for contrast determination in fringe patterns. Simulated and experimental results are presented.     

High-throughput method for lipophilicity measurement

A high-throughput method has been developed for lipophilicity measurement. It measures the partition coefficient of a solute between a polymer phase and an aqueous phase (Ppw) in a 96-well format. The polymer is plasticized poly(vinyl chloride) (PVC), which is widely used as a material for clinical containers and ion-selective electrodes. The composition is 2:1 (w/w) dioctyl sebacate and PVC. With six repeats, log Ppw values of 15 solutes have been determined in one 96-well microplate in 4 h. A linear relationship between log Ppw and log Pow (octanol-water partition coefficient) values exists with a correlation coefficient of 0.979. The slope and intercept of the log Ppw vs log Pow plot are statistically indistinguishable from 1 and 0, respectively. Similar to the HPLC method, by using the correlation line as a calibration curve, the measured log Ppw values can be used to predict log Pow. This protocol is faster than the HPLC method. Moreover, it is straightforward to extend the protocol to the determination of the distribution coefficient and pKa of charged solutes. We show that the log Ppw of the neutral form of racemic econazole is 4.83(+/-0.06), for the cationic form (presumably as a dihydrogen phosphate ion pair) 1.68(+/-0.04), and the pKa is 6.15(+/-0.04). This method has great flexibility as well and is potentially fully automated.     

New method of stopping power measurement for fast particles in metals and liquids

A new method of stopping power measurement for fast incident particles penetrating through solid and liquid targets is developed. In this method, thin cylindrical targets are employed and it enables us to obtain the stopping powers in a rather wide range of projectile energies according to a certain incident energy. In this report, we demonstrate our recent experimental results for a metal wire of Al and liquid water and ethanol obtained using a molecular jet technique. We also present here the results of secondary ion emission from liquid targets measured by this method.     

New method for measurement of the concentration of acceptor centers in photorefractive crystals

A new method for measurement of the concentration of deep traps is proposed and confirmed theoretically and experimentally. The method involves measuring the intensities of the signals formed by the first and second harmonics of a holographic grating. Pis’ma Zh. Tekh. Fiz. 24, 56–60 (May 12, 1998)     

基于CMOS图像传感器的微小变形测量系统

近年来，图像处理在微小变形的测量中应用越来越广泛，它具有方便灵活、对被测对象没有任何伤害等优点，且只需对被测对象进行拍照，然后对图像进行处理分析，利用亚像素法原理即可精密测量出试样的微小变形。因此，利用AT89C51与CMOS图像传感器OV5017组成DMA方式数据采集系统，FT245BM虚拟USB口与PC机通讯，实现了对纵向和横向两个方向微小变形的无接触精密测量，且精度高成本低。     

New configuration for realizing universal voltage-mode filter usingtwo current feedback amplifiers

A new universal biquadratic filter configuration using two current-feedback amplifiers (CFAs) is presented. The circuit has three inputs and one low-impedance output and can realize all the standard filter functions, that is, highpass, bandpass, lowpass, notch, and allpass filters, without changing the passive elements. The proposed circuit has no requirements for component matching conditions and uses only four passive components. The center frequency and bandwidth can be orthogonally controllable. Also, the active and passive sensitivities are low     

一种新的SLM显微立体视觉畸变矫正模型

提出了一种描述SLM(Stereolightmicroscope)显微立体视觉成像的新模型,使用了新物理量“弱视差”来提高模型的三维微观定位精度。新模型考虑了信号滞后、径向、偏心和薄透镜等四种畸变,建立了精确的畸变矫正模型。在畸变参数标定中,采用了显著性检验和相关性检验两种方法,动态检测畸变参数对模型的影响程度。实验中对14个畸变参数的显著性进行分析,其中5个低于水平0.05的临界值,表现不显著,说明显著性检验对畸变参数的选择具有一定的意义。     

A method for concrete bleeding measurement

Several methods were proposed in the past to measure concrete bleeding, but none of them gives complete satisfaction. The method presented herein consists in sucking water with a pipette, in tracks made on the top surface of concrete just after casting. It takes water evaporation into account. Three tests are carried out simultaneously with three samples of different initial heights. Comparison of the results leads to know whether bleeding is localised (in channels) or not. The average bleeding rate of tests that exhibit no channel is the major result of the test; it is found to be rather repeatable. Overall, this method is believed to be more accurate than the previous ones, since any movement of the sample is avoided during test. Also, a double weighing of water is carried out.     

A method for ultrasensitive magnetostriction measurement

Determination of Joule magnetostriction by the method of tensile strain measurement has a lower limit of about 10^-6because of error strains clue to magnetostatic forces and changes in temperature. It is shown that these disturbances can be eliminated by measuring shear strains induced in thin-walled tubes by helical magnetic fields. By a resonance method, the measurement of the magnetostriction constant can be made down to 10^-13.     

Efficient numerical method for predicting the polarization-dependent Raman gain in fiber Raman amplifiers

Polarization-dependent gain (PDG) of fiber Raman amplifiers (FRAs) will degrade the performance of optical communication systems. An efficient numerical model is presented to predict PDG quantitatively by substituting the polarization-dependent polarization factor for the constant one in the coupled nonlinear equations usually adopted. The simulation is carried out by estimating the polarization length by use of the average polarization-mode dispersion of the tested fiber; the results, including the Raman gain profile and the fluctuation of the PDG, are highly accordant with the experimental data reported previously. The model can aid in the design of FRAs and in the analysis of system performance.     

基于虚拟变形法的移动质量识别方法研究

在车-桥耦合系统的移动质量(荷载)识别反问题中,识别移动质量会面临重构系统、优化缓慢的问题;而若直接识别移动荷载常常会遇到病态问题且对噪音敏感。针对这些缺陷,根据虚拟变形法(VDM)的结构快速重分析思想,提出移动动态影响矩阵,实现利用较少的传感器即可快速而准确地识别移动质量(荷载)。以移动质量为优化变量,避免了识别荷载常遇到的病态问题,对噪音鲁棒性强;且需要传感器信息少。每步优化中,利用移动动态影响矩阵,无需时时重构车-桥耦合系统的时变系统参数矩阵,优化效率高。VDM方法的思想是将实际结构的响应计算转化为初始结构模型在相同外荷载作用下的响应,与在结构模型发生改变的位置施加相关的虚拟变形或虚拟力引起的响应的线性叠加。通过简支梁模型和框架梁模型验证了该方法的可行性和有效性,即使在5%的噪声影响下,利用一个传感器就可以很好地识别多个移动质量。     

Indirect method of measuring small harmonic distortion factors

An indirrect method is proposed for measuring small harmonic distortion factors, with a high accuracy. An analysis of methodological errors is given. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 55–56, May, 1995.     

An acoustic method for soil moisture measurement

The paper deals with the problem of measuring the moisture of agricultural soils by an accurate, on-site, real-time method. The idea is to estimate the moisture by measuring the speed of sound in the medium: the main issue is therefore to determine a precise relationship between the two quantities. To this purpose, the Brutsaert's model for elastic waves in porous media is applied, taking into consideration different kinds of soil of common interest in agriculture. The authors have derived the speed-moisture curves, the conditions for the actual validity of the curves, and the suitable sound frequency for performing the measurement, for a wide range of agricultural soils in different physical conditions. The paper results are therefore the basis to realize an inexpensive and accurate moisture sensor for farmers.