Mahematically fuzzy summation and optimization of measurement errors in a technological operation

The paper discusses mathematically fuzzy summation of measurement errors in a technological operation on rules that differ from those usually employed for additive or quadratic summation. To optimize the errors, a linear programming method is proposed with control variables in the form of carriers of these errors. As in the mathematically nonfuzzy case, two self-conjugate optimization methods are employed: functional and economic. Paper written on the basis of the report presented at the 10th All-Russia Conference on Measurement State and Problems, which was held at the Bauman Moscow State Technical University in April 2008 (see selection of articles in Measurement Techniques, Nos. 10 and 11 (2008)). Translated from Izmeritel’naya Tekhnika, No. 2, pp. 12–17, February, 2009.     

Summation of random and residual systematic components of errors in direct measurements

Some universally adopted procedures for summation of errors in direct measurements are discussed. Conditions under which the methods applied yield noncontradictory results are stated. Practical recommendations for summation of random and residual systematic error components of direct measurements are provided. Translanted from Izmeritel'naya Tekhnika, No. 6, pp. 9‐11, June, 1998.     

Measurement Error Summation and Optimization in a Technological Operation

A tabular tolerant structure is proposed with allowance for the errors of measurement during acceptance, operation, and delivery, together with corresponding formulas for summation enabling one to determine the proportions of them in the total error for the technological operation quality parameter. __________ Translated from Izmeritel'naya Tekhnika, No. 10, pp. 20–23, October, 2005.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

A method of measuring the vectors of jointly acting harmonic signals by sampling them and summing the samples

A method for the rapid separate measurement of the vectors of jointly acting harmonic signals using frequency-dependent sampling and summation of the samples is considered. A theoretical justification of the method is given and the measurement errors and the possibility of realizing the method in practice are discussed.     

用参数优化整体逼近方法构造NURBS曲线等距线

从原始ＮＵＲＢＳ曲线求得一组精确等距点后用最小二乘法拟合等距线。用参数优化方法提高等距线的逼近精度。优化目标函数为各精确等距点至拟合曲线的距离平方和取极小值。     

Convergence criteria for scattering models of ultrasonic wave propagation in suspensions of particles

Scattering models used to simulate the attenuation and phase velocity of an ultrasonic wave propagating through a suspension of particles involve the summation of an infinite series of partial waves. The accuracy of computation is influenced by the number of terms included in the harmonic series, and the number of terms required depends upon the scatterer size compared with wavelength. It is shown that the errors in modelled attenuation and phase velocity resulting from premature truncation can be significant when modelling higher values of particle diameter-frequency product. A useful and simple heuristic is presented, in which the number of terms in the summation of the infinite series needed for satisfactory convergence to a final value is a function of the particle diameter-frequency product and of the compressive wave velocity in the continuous phase     

Shielding evaluation of a medical linear accelerator vault in preparation for installing a high-dose rate 252Cf remote afterloader

In support of the effort to begin high-dose rate 252Cf brachytherapy treatments at Tufts-New England Medical Center, the shielding capabilities of a clinical accelerator vault against the neutron and photon emissions from a 1.124 mg 252Cf source were examined. Outside the clinical accelerator vault, the fast neutron dose equivalent rate was below the lower limit of detection of a CR-39 etched track detector and below 0.14 +/- 0.02 muSv h(-1) with a proportional counter, which is consistent, within the uncertainties, with natural background. The photon dose equivalent rate was also measured to be below background levels (0.1 muSv h(-1)) using an ionisation chamber and an optically stimulated luminescence dosemeter. A Monte Carlo simulation of neutron transport through the accelerator vault was performed to validate measured values and determine the thermal-energy to low-energy neutron component. Monte Carlo results showed that the dose equivalent rate from fast neutrons was reduced by a factor of 100,000 after attenuation through the vault wall, and the thermal-energy neutron dose equivalent rate would be an additional factor of 1000 below that of the fast neutrons. Based on these findings, the shielding installed in this facility is sufficient for the use of at least 5.0 mg of 252Cf.     

Effect of prior plastic deformation and creep strain on fatigue damage for a high-temperature alloy

A procedure is developed, an experimental study is provided, and a comparative evaluation is given for the effect of prior plastic deformation and creep strain on fatigue damage for high-temperature metallic materials on the example of alloy éI827. A different effect is demonstrated for prior plastic deformation and creep strain on fatigue damage of this alloy at 1073 K. In the case of prior creep a marked difference is established from the hypothesis of linear summation for damage in the direction of weakening during evaluation of the overall fatigue and static damage both in the form of relative endurance and relative strain.     

A Study of Errors due to Reconstruction Filters in Computed Tomography

Abstract

In the summation convolution backprojection method of image reconstruction in computed tomography, the final image accuracy depends on the convolution filter used. Filters are designed to attenuate high spatial frequencies when noisy projection data are used. This paper explores the differences between the images reconstructed using a range of filters, and compares the results with the case of the ramp filter that provides the “best” image for ideal, noise-free, projection data. It is shown that systematic errors between these images and the best image exist, and that these errors are related to the second differential of the reconstruction filter with respect to spatial frequency. This error determination may be used to correct computed tomography images that have been reconstructed using inappropriate filters, and this theory is tested using noise-free projection data from two computer simulated images. It is shown that the corrected images are far closer to the original images.     

A study of errors due to reconstruction filters in computed tomography

In the summation convolution backprojection method of image reconstruction in computed tomography, the final image accuracy depends on the convolution filter used. Filters are designed to attenuate high spatial frequencies when noisy projection data are used. This paper explores the differences between the images reconstructed using a range of filters, and compares the results with the case of the ramp filter that provides the “best” image for ideal, noise-free, projection data. It is shown that systematic errors between these images and the best image exist, and that these errors are related to the second differential of the reconstruction filter with respect to spatial frequency. This error determination may be used to correct computed tomography images that have been reconstructed using inappropriate filters, and this theory is tested using noise-free projection data from two computer simulated images. It is shown that the corrected images are far closer to the original images.     

Deterministic and probabilistic contingency selection

Abstract

Steady‐state contingency selection is performed on the Taiwan power system using both deterministic and probabilistic approaches. In the deterministic approach, both the real power performance index (PIp) and the voltage performance index (PIv) are evaluated to reach the desired ranking lists of line outages. Generator reactive power output limits (Q‐limits) are taken into account throughout the contingency selection procedure. To examine the effect of voltage control on contingency selection, both the case with a fixed tap changer position and the one with a variable tap changer position are considered. An important observation from this study is that the masking problem, which has been reported to take place in real power contingency selection, does not seem to appear in voltage contingency selection. Thus, it is recommended that in voltage contingency selection the summation in PIv be made over all buses while in real power contingency selection the summation in PIp be carried out only on overloaded lines. A new method for probabilistic contingency selection is also developed using the outage statistics of Taiwan power systems.     

单次相移数字全息中相移值的提取

为了消除相移误差对数字全息中再现像的像质的影响,本文时单次相移数字全息进行了研究.基于相位统计特性,提出了一种有效消除相移误差的新方法,该方法能够对任意未知相移量进行提取,并利用数字全息图所有抽样点的强度偏差之和作为评价标准,通过逐步改变计算得到的初始相移值来寻找正确的实际相移角.计算机模拟得到了很好的再现结果,证明了该方法的可行性和有效性.     

Sampling period criterion in a scanning-beam technique

The scanning-beam technique for measuring the response of a detector to an irradiance is analyzed. With this method the irradiance responsivity is determined by integration of the spatial responsivity. Since in practice the integration is approximated by a summation over steps with a finite step size, errors are introduced. It is shown both theoretically and experimentally that the error vanishes when the reciprocal step size lies beyond the diffraction limit. Furthermore, comparison shows that experiment and theory are in good agreement.     

基于电场作用的混凝土渗透性评价方法研究进展与展望

渗透性是反映混凝土耐久性最为直接的指标,基于外加电场的作用可快速评价混凝土的渗透性。通过对比分析现有基于外加电场作用下的混凝土渗透性评价的测试手段,总结了不同方法的实验条件差异。认为应进一步研究外加电场的作用和混凝土的材料组成所引起的误差,加强评价方法的基础理论研究。提出了通过改变实验条件和引入混凝土电学性质变化率的定量评价方法的设想,以及重点开展在役混凝土结构评价方法研究的建议。     

Method for the evaluation of the service life under random loading based on the energy criterion of fatigue fracture

We propose a method aimed at the assessment of the service life of structural elements under random loads based on the energy criterion of fatigue fracture and the model of cyclic deformation of materials after overloading. The possibility of determination of the maximum amplitude of stresses according to the number of loading cycles prior to fracture is substantiated. The results of evaluation of the service life under conditions of uniform stressed state are compared with the experimental data obtained by Swanson, Raikher spectral hypothesis of summation of defects, and linear hypothesis of summation. The dependence of the right-hand side of the linear hypothesis equation on the dispersion of the random loading process is established. __________ Translated from Problemy Prochnosti, No. 2, pp. 82–97, March–April, 2008.     

Validation of analytical methods using a regression procedure

The evaluation and validation of analytical methods and instruments require comparison studies using sample material for testing accuracy and precision. In analytical chemistry, the commonly accepted means of analyzing data from method comparison studies is least-squares regression analysis, a model which has limitations. In this paper, the results from ordinary least-squares and many other regression approaches recommended in the literature were compared with a new regression procedure that takes into account the errors in both variables (methods). After a discussion of the properties of the regression procedure, recommendations are given for carrying out a method comparison study using informational analysis of variance. The efficiency of the regression procedure proposed is demonstrated by applying it to different data sets from published literature.     

Criteria for negligible smallness of random and systematic components of measurement errors

The problem of numerical values of criteria for negligible smallness of random and (residual) systematic components of the total measurement error is investigated within the framework of a well-known approch to estimation of measurement errors (GOST 8.207-76). Various aspects of this problem are analyzed. A correct procedure for obtaining the limiting values of the relative error of estimation is presented. Estimation errors — corresponding to several values of criteria for negligible smallness recommended in the literature are compared. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 3–7, July, 1996.     

Random and systematic errors in case–control studies calculating the injury risk of driving under the influence of psychoactive substances

Between 2006 and 2010, six population based case–control studies were conducted as part of the European research-project DRUID (DRiving Under the Influence of Drugs, alcohol and medicines). The aim of these case–control studies was to calculate odds ratios indicating the relative risk of serious injury in car crashes. The calculated odds ratios in these studies showed large variations, despite the use of uniform guidelines for the study designs. The main objective of the present article is to provide insight into the presence of random and systematic errors in the six DRUID case–control studies. Relevant information was gathered from the DRUID-reports for eleven indicators for errors. The results showed that differences between the odds ratios in the DRUID case–control studies may indeed be (partially) explained by random and systematic errors. Selection bias and errors due to small sample sizes and cell counts were the most frequently observed errors in the six DRUID case–control studies. Therefore, it is recommended that epidemiological studies that assess the risk of psychoactive substances in traffic pay specific attention to avoid these potential sources of random and systematic errors. The list of indicators that was identified in this study is useful both as guidance for systematic reviews and meta-analyses and for future epidemiological studies in the field of driving under the influence to minimize sources of errors already at the start of the study.     

Ranking alternatives via maximizing set and minimizing set based fuzzy MCDM approach

Abstract

This work suggests a maximizing set and minimizing set based fuzzy multiple criteria decision‐making (MCDM) model, where criteria are classified into cost and benefit criteria. The final fuzzy evaluation value of each alternative is developed based on the concept of subtracting the summation of weighted normalized benefit ratings from that of weighted normalized cost ratings. Using interval arithmetic of fuzzy numbers can develop the membership functions for the final fuzzy evaluation values. Chen's maximizing set and minimizing set is then applied to defuzzify all the final fuzzy numbers for ranking alternatives. Formulas for the membership functions and ranking procedure of the final fuzzy numbers are clearly presented. The suggested method provides an extension to the fuzzy MCDM techniques available. A numerical example demonstrates the computational process of the proposed method.