Determination of test signal parameters to estimate the technical state of information-measuring-system channels

Measurement Techniques -     

Use of redundancy to raise reliability of determining motion parameters of a solid

Measurement Techniques -     

Use of the pulse-characteristics method to estimate the parameters of acoustic pickups with ring antenna arrays

It is shown that the use of the pulse-characteristics method enables the spatial-frequency parameters of an acoustic pickup with any form of antenna arrays to be calculated fairly simply.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 60–62, April, 1995.     

震源参数对地震动相干函数的影响

基于运动学震源模型,以弹性半空间作为传播介质模型,采用显式有限元数值模拟方法进行强地面震动数值模拟,根据模拟结果考察了震源深度、断层破裂子源大小、破裂速度和断层走向等震源参数对地震动相干函数的影响,结果表明:震源深度和断层走向对相干函数的影响较大。并根据统计结果给出了一个基岩地震动的相干函数模型。     

Selection of parameters of the kernel of a frequency-time distribution to evaluate the parameters of a unsteady signal

Aspects of the use of Cohen-type frequency-time distributions are studied in order to quantitatively evaluate the parameters of unsteady multicomponent signals. The selection of parameters of the kernel the distribution that solve the stated problem is examined. Translated from Izmeritel'naya Tekhnika, No. 11, pp. 36–39, November, 1998.     

段药量对爆破振动信号时频特性的影响研究

为研究段药量对爆破振动信号时频特性的影响,进行不同段药量的单孔爆破振动试验。基于实测数据,利用小波分析和ＡＯＫ时频分布相结合的方法,对不同段药量的爆破振动信号在不同频带内展开,并以频带能量比、频带能量持续时间为指标,研究段药量对爆破振动信号时频特性的影响。结果表明,段药量对爆破振动信号时频特性影响很大：随着段药量的增加,爆破振动信号的低频能量所占总能量的比例增加且频带能量的持续时间相应延长。研究成果可揭示段药量对爆破振动信号时频特性的影响,并为从能量的角度进行抗振、降振的研究提供分析基础。     

Measurement of time-frequency parameters of picosecond optical pulses

A method is proposed that permits accurate and reliable measurement of the train-average pulse duration as well as the value and sign of the frequency chirp of picosecond optical pulses in high-repetition-rate trains.     

Use of digital filters to determine the frequency of a sinusoidal signal

An interference-protection-optimum method of measuring the frequency of sinusoidal signals using digital filters, based on the root mean square deviation criterion, is investigated. An algorithm for the digital processing of the input signal is proposed, and a model of a digital filter for achieving this and the principle of the construction of a digital measuring instrument for determining the parameters of a sinusoidal signal are proposed.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 60–63, 1994.     

Comparative performance analysis of time-frequency distributions for spectroscopic optical coherence tomography

The analysis of spectroscopic optical coherence tomography (SOCT) signals suffers the trade-off between time resolution and frequency resolution. Various joint time-frequency distributions (TFDs) can optimize this trade-off. Synthesized signals were generated and experimentally acquired data were obtained to compare and validate several different TFDs under different SOCT imaging schemes. Specific criteria were designed to quantify the TFD performance. We found that different SOCT imaging schemes require different optimal TFDs. Cohen's class TFDs generate the most compact time-frequency (TF) analysis, while linear TFDs offer the most reliable TF analysis. In both cases, if some prior information is known, model-based TF analysis can improve the performance.     

The use of numerical methods to estimate the errors in determining the parameters of a crystal structure

The use of numerical methods to estimate the components of the instrumental and systematic errors of measurements of the parameters of a crystal structure using an x-ray diffractometer is considered. The criteria for using standard samples to eliminate instrumental errors are established. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 61–64, March, 2006.     

Evaluating the parameters of the signal of a laser-Doppler vibrometer

The method of maximum similitude is used to estimate vibration characteristics on the basis of the signal obtained from a laser-Doppler vibrometer. The accuracy of the estimates is evaluated on the basis of statistical modeling, the results of which are also presented. Translated from Izmeritel'naya Tekhnika, No. 12, pp. 30–32, December, 1998.     

An efficient algorithm to estimate material parameters of biphasic mixtures

The paper describes an inverse numerical experimental method to determine material parameters for biological tissues. Measured field quantities are compared to calculated field quantities. The field equations are solved with the finite element method, using an assumed constitutive model and estimations of the material parameters. The parameter estimates are improved iteratively by means of an algorithm that calls the finite element program as a subroutine. The paper is focused on biological materials that can be described as biphasic mixtures. An efficient recursive algorithm is presented. All parameters are determined on the basis of displacements and pressures measured at different positions within the material at subsequent points in time. A pseudo‐analytical approach is used to determine the sensitivity matrix. The algorithm has been tested in a simulation of an experiment on a mixture of a solid and a fluid. It appears that for this example an iterative loop to determine the material parameters requires no more than 30 per cent more CPU‐time than one straightforward analysis of the problem. Copyright © 1999 John Wiley & Sons, Ltd.     

Using pore parameters to estimate permeability or conductivity of concrete

This study investigated the relationships between pore parameters and transport properties. Fourteen concrete mixtures were investigated for water permeability, conductivity for the pore solutions and bulk concrete, as well as total porosity and critical pore diameter. The measured parameters allowed comparison to the Katz–Thompson relationship as well as Archie’s Law. Using a low-pressure device, measured permeability from 1 to 28 days was found to be approximately an order of magnitude higher than that calculated using the Katz–Thompson relationship for the six mixtures examined with this technique. Better agreement between measured and predicted permeability was found using apparatus capable of higher applied pressure. Comparing the data to other published data, the Katz–Thompson relationship seems to be a useful technique for the approximation of water permeability. The exponential relationship between porosity and normalized conductivity (the inverse of the Formation factor) forming the basis of Archie’s Law was found to hold within each specific concrete mixture. However, no overall trend was apparent. The constants of the Archie’s Law vary over a wide range.     

爆破振动信号时频特征的三维分形特性研究

为进一步研究爆破振动信号能量特征,基于小波包变换方法对爆破振动信号时频能量特征进行分析。在二维矩形盒维数模型的基础上建立了计算三维曲面分形盒维数模型,并计算得到实测爆破振动信号时频能量谱的三维分形盒维数D3d=2.148 8。该分形维数满足空间分形条件2D3d3,验证了爆破振动信号时频能量谱具有三维分形特征。经研究三维分形曲面盒维数D3d与其剖面二维分形盒维数D2d之间的数值关系,表明计算空间分形曲面分维数的常规假设D3d=D2d+1并非严格成立。研究表明,所提出的长方体覆盖空间曲面的分形维数计算方法可行、有效,为进一步研究爆破振动信号特征、控制爆破地震效应提供了新的研究思路。     

Ion energy distributions in a special glow-discharge ion source

The ion energy distributions for a special glow-discharge source were obtained by two means: theoretical and experimental. The experimental energy distributions, determined by mass spectrometry, differ significantly from the theoretical energy distributions calculated according to the Davis model in which the charge transfer process plays an important part. Space potential distributions necessary in the Davis theory, were determined with an electrostatic probe. The differences between the distributions, calculated and measured, can be caused by some inaccuracy of the ‘simple’ Davis model.     

Operational method of measuring the parameters of a harmonic signal

A method of measuring the parameters of a harmonic signal containing a constant an slowly varying component is proposed and investigated. The method has optimum interference proctection. Expressions are obtained for the algorithms for processing the input signal in analog and digital versions, an estimate of the errors in measuring the parameters is given, and the principle for constructing a digital microprocessor measuring instrument is described. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 47–51, July, 1995.     

基于广义解调时频分析的多分量信号分解方法

广义解调时频分析方法是一种新的信号处理方法，该方法将广义解凋和最大重叠离散小波包变换相结合对复杂信号进行分解，得到若干个瞬时频率和瞬时幅值都具有物理意义的单分量信号，从而获得原始信号完整的时频分布。本文在介绍广义解调时频分析方法的基础上，将该方法用于多分量信号的分析，对该方法进行了改进，给出了由改进的广义解调时频分析方法分解多分量信号的具体步骤，从而由改进后的广义解调时频分析方法不仅可以得到原始信号中各个分量的时域波形，而且还可以得到相同的时频分布。采用改进后的广义解调时频分析方法对仿真信号进行了分析，同时和其它时频分析方法进行了比较，结果表明了该方法的有效性。最后，对广义解调时频分析方法中的相位函数选择问题进行了讨论。