声强测量中系统误差修正的若干问题研究

本文对用残余声强法修正声强测量的系统误差进行了理论分析，推导了它的误差表达工式，给出了该误差的二元分布图。     

测量不确定度最大残差系数的一种新算法

在测量不确定度的评定中,用测量数据的最大残差乘以适当的系数获得标准差的方法称为最大残差法。通过对最大残差的分布函数及其数字特征的分析研究,建立了最大残差的概率模型,并且利用蒙特卡罗模拟及Matlab软件,提出了计算测量不确定度最大残差系数的一种新方法,求出了当测量次数小于50时,最大残差所对应的分布函数、均值、标准差和自由度的数值,并给出了最大残差法的系数表。最后通过测量实例验证了理论分析的正确性。用文中提出的方法可简单、迅速、可靠地计算出所需要的标准差数值。     

误差理论的新哲学观

针对系统误差与精度概念之间的逻辑纠葛,以及通过对测量界最典型系统误差的分析,揭示误差分类学说 其实是源于专业分工过细而导致的一种狭隘视角,是一种类似盲人摸象的狭义哲学观。通过对系统误差也遵循随机分布的证明和相关问题的讨论,提出所有误差都遵循随机分布这一新型的误差认识论,同时证实了测量不确定度概念体系的唯一科学性,给出了误差分类定义及其衍生出来的精度、正确度和准确度等概念应当删除的论据。     

Error in measuring one-dimensignal probability distribution functions of random processes

Conclusions The relative error of the above method for measuring a one-dimensional integral probability distribution function is determined from (6) and it depends on the type of the measured function. It was shown, as an example of a normal distribution law, that the above error decreases with an increasing distribution function argument.The relative error in measuring the values of a probability distribution function does not depend on the type of the function and is detemined from (8). An effective means for raising the measurement precision consists of setting appropriately the pulse counter triggering threshold. The measurement error tends to its minimum value when x_t=1/2x_s.Translated from Izmeritel'naya Tekhnika, No. 7, pp. 20–23, July, 1969.     

Joint Monitoring of Process Location and Dispersion Based on CUSUM Procedure and Generalized Likelihood Ratio in the Presence of Measurement Errors

In this paper, we propose a new methodology based on the combination of cumulative sum procedure and generalized likelihood ratio statistic for joint monitoring of the process location and dispersion. Then, we explore the effect of measurement errors on detecting ability of the proposed control chart when (i) the variance of measurement error is constant (ii) the variance of measurement error increases linearly as the level of the process mean increases. We also utilize multiple measurements on each sample point in order to decrease the adverse effects of measurement errors on the performance of the proposed control charts. Two numerical examples based on simulation studies are given to evaluate the ability of the proposed methods in terms of average run length, median run length, standard deviation of run length, and the first and third quantile points of the run length distribution (Q₁ and Q₃). Finally, a real life example is given to illustrate the application of the proposed method. Copyright © 2017 John Wiley & Sons, Ltd.     

A simulation-based experimental investigation of supply/timing uncertainty in MRP systems

The uncertainty inherent in material requirements planning (MRP) systems is of two general types: demand uncertainty and supply uncertainty. Supply uncertainty is a result of late deliveries (timing) or order shrinkage (quantity) or both. The purpose of this paper is to examine the impact of operating policies on an MRP system given supply uncertainty resulting from timing factors, specifically the uncertainty caused by variability in the lead time of purchased parts. Experiments arc conducted to assess the impact of four factors: the amount of lead time variability, the amount of safety stock or safety lead time, the lot-size rule, and the holding cost and lateness penalty, on the total cost of the MRP system given supply/timing uncertainty. An MRP/Production simulator is employed to perform the experiments. Practical guidelines for the manager of an MRP system with supply/timing uncertainty are presented.     

Revisiting rescheduling: MRP nervousness and the bullwhip effect

We study the material requirements planning (MRP) system nervousness problem from a dynamic, stochastic and economic perspective in a two-echelon supply chain under first-order auto-regressive demand. MRP nervousness is an effect where the future order forecasts, given to suppliers so that they may plan production and organise their affairs, exhibits extreme period-to-period variability. We develop a measure of nervousness that weights future forecast errors geometrically over time. Near-term forecast errors are weighted higher than distant forecast errors. Focusing on replenishment policies for high volume items, we investigate two methods of generating order call-offs and two methods of creating order forecasts. For order call-offs, we consider the traditional order-up-to (OUT) policy and the proportional OUT policy (POUT). For order forecasts, we study both minimum mean square error (MMSE) forecasts of the demand process and MMSE forecasts coupled with a procedure that accounts for the known future influence of the POUT policy. We show that when retailers use the POUT policy and account for its predictable future behaviour, they can reduce the bullwhip effect, supply chain inventory costs and the manufacturer’s MRP nervousness.     

合肥800MeV同步辐射源光谱特性的测量

本文介绍了测量合肥国家同步辐射实验室８００ＭｅＶ同步辐射源光谱功率分布的原理、装置和方法，并对实验结果进行误差分析。     

Influence of lower stratospheric aerosol variations on guidestar performance

The probability distribution function for the logarithm of the mixing scatter ratio, based on long-term measurements of lower-stratospheric aerosol loading, is derived to model variations in total backscatter coefficient and extinction profiles in the visible and the near infrared (NIR). The profiles are used to estimate signal-to-noise ratio, laser-pulse energy, and wave-front measurement error with respect to backscatter strength, guidestar pulse length and altitude, and pixel noise. The results show that for a given wave-front measurement phase error (1) visible guidestars require less pulse energy for aerosol concentrations near background, where molecular backscatter dominates, and (2) for high aerosol loading following a major volcanic event, a NIR guidestar can reduce the energy requirement below that for visible sensing.     

Interferometry at the physical limit: how to measure sub-parts-per-million optical homogeneity in fused silica

Inspection of the refractive-index distribution in fused silica is very sensitive to thermally induced measurement errors. A model is derived for the estimation and interpretation of thermal errors applicable to interferometric homogeneity investigations. The outlines of the model are supported by experimental investigations and numerical calculations. The results state a mandatory temperature stability of deltaT = 0.02 K for a required reproducibility of sigma(delta(n)) < or = 1 x 10(-7) and a lower sensitivity of higher-order Zernike terms. Requirements of the interferometer environment include spatial and temporal stability. Only a small part of the frequency spectrum of temporal instabilities contributes significantly to the measurement error and is therefore critical for the system. Experimental values are given for different environmental conditions.     

Approximate estimates of limiting errors of passive wireless SAW sensing with DPM

This paper discusses approximate statistical estimates of limiting errors associated with single differential phase measurement of a time delay (phase difference) between two reflectors of the passive surface acoustic wave (SAW) sensor. The remote wireless measurement is provided at the ideal coherent receiver using the maximum likelihood function approach. Approximate estimates of the mean error, mean square error, estimate variance, and Cramér-Rao bound are derived along with the error probability to exceed a threshold in a wide range of signal-to-noise ratio (SNR) values. The von Mises/Tikhonov distribution is used as an approximation for the phase difference and differential phase diversity. Simulation of the random phase difference and limiting errors also is applied.     

Influence of probe size on the measurement accuracy of non-uniform ELF magnetic fields

The accuracy of extremely low frequency (ELF) magnetic field measurements can be sensitively varied by the meter probe size when the spatial distribution of the magnetic flux density is highly non-uniform, e.g. if the measurement point is close to the field source. The deviation between measured and actual field varies from point to point depending on the probe dimension and on the source configuration, once the other measurement conditions are fixed. The analysis of this effect is developed through a two-dimensional numerical model that enables the evaluation of the actual field value and of the corresponding probe indication. The error distribution, i.e. the deviation between actual and measured value, is computed for magnetic fields generated by industrial three-phase systems under both balanced and unbalanced supply conditions. The analysis shows how, for a given source, the error depends not simply on the distance from the source in relation to the probe size, but on its spatial distribution, which is complex and cannot be a priori predicted without using a computational tool such as the one proposed.     

提高线阵CCD测量光束中心位置精密度的方法

用线阵CCD测量类钟形分布的光束中心位置时，常用高斯分布模型和最小二乘（LSM）回归计算。提出一种用准高斯分布以提高测量灵敏度、用截取阈值较高的方式以减少噪声影响、用加权LSM回归以提高精密度的方法。由于高斯曲线拟合时的因变量不等权，选用加权回归和等权回归相比，ADC化整误差和光电测量误差的影响将减小一个数量级。根据CCD器件的参数，能够确定像元数据的误差限值。再用蒙特卡罗法模拟误差分布规律，通过截尾分布数值的加权回归，求出使测量精密度提高的合理光束宽度范围。已将此方法用于冲击电流计的改进设计和位移测量，使微电流测量的精密度提高达两个数量级，并使30mm内的微位移测量的非线性标准差不大于0．0025％。     

脉冲波形占空比的数字化测量及不确定度分析

介绍了脉冲波形占空比的3种数字化测量方法,它们分别是直接脉宽测量法、幅值统计测量法和平均值测量法。讨论了主要的不确定度来源,包括众数判别区间的影响、波形测量系统幅度测量误差的影响等等,给出了不确定度分析与评价过程．并结合一个实例,给出了脉冲波形占空比的不确定度评价结果。     

Planning measurements in certifying methods of performing measurements

A procedure is proposed for planning measurements in certifying a linear measurement method MM, and estimates are made of the adequacy of a linear MM. Translated from Izmeritel’naya Tekhnika, No. 1, pp. 60–69, January, 1998.     

Examining the impact of demand lumpiness on the lot-sizing performance in MRP systems

Material requirements planning (MRP) systems are designed to deal with production scheduling for products with lumpy demand patterns, as opposed to the continuous demand assumed in the classical inventory models. Past MRP lot-sizing studies concluded that the MRP system performance improves as the demand becomes lumpier. The purpose of this paper is to examine the impact of various degrees of demand lumpiness on the system performance of MRP systems by a simulation study. Results show that the performance improves to u certain extent as the demand becomes lumpier. However, the system performance starts to deteriorate when the demand pattern becomes extremely lumpy. MRP users should exercise caution in the introduction of demand lumpiness in the master production schedule (MPS) to induce a better MRP system performance. If a certain degree of demand lumpiness exists in the MPS as given in an operating environment, then the choice of an appropriate lot-sizing rule, such as the Silver-Meal algorithm, could lake advantage of the impact of demand lumpiness.     

Empirical best prediction under area-level Poisson mixed models

The paper studies the applicability of area-level Poisson mixed models to estimate small area counting indicators. Among the available procedures for fitting generalized linear models, the method of moments (MM) and the penalised quasi-likelihood (PQL) method are employed. The empirical best predictor (EBP) of the area mean is derived using MM and compared with plug-in alternatives using MM and PQL. The plug-in estimator using PQL is computationally faster and provides competitive performance with respect to EBP that involves high complex integrals. An approximation to the mean squared error (MSE) of the EBP is given and three MSE estimators are proposed. The first two MSE estimators are plug-in estimators without and with bias correction to the second order and the third one is based on parametric bootstrap. Several simulation experiments are carried out for analysing the behaviour of the EBP and for comparing the estimators of the MSE of the EBP. A good choice in practice is the bootstrap alternative since it performs similarly to the analytical versions and is computationally faster. The developed methodology and software are applied to data from the 2008 Spanish living condition survey. The target of the application is the estimation of poverty rates at province level.     

Determining alignment in measurement of a large-diameter thread by means of devices for profile measurement

An analytic estimation of the inaccuracy of the alignment of a thread gauge on a device that must be taken into account in the measurement of the accumulated error of the thread pitch is given. For an M170.6 thread, the measurement error of the accumulated pitch reaches 0.008 mm on a length of 200 mm. Translated from Izmeritel’naya Tekhnika, No. 12, pp. 13–16, December, 2008. An erratum to this article can be found at     

The analysis of feature-based measurement error in coordinate metrology

Coordinate measurement systems (CMSs) dominate the dimensional control and diagnostics of various manufacturing processes. However, CMSs have inherent errors caused by the lack of a tracing ability for some of the measured part features. This is important for product inspection and process variation reduction in a number of automated manufacturing systems, such as for example the automotive body assembly process. The lack of a feature tracing ability means that instead of measuring a given feature, the CMS may actually measure the area around the selected feature. In this paper, a principle for the part feature tracing ability and the resultant feature-based measurement error analysis are developed to estimate the aforementioned deficiencies in the CMSs. The impact of feature type and part(s) positional variation on the feature-based measurement error is explored. The proposed approach is applicable to both contact and non-contact CMSs including both mechanical and optical coordinate measuring machines An analysis of the error for different measurement algorithms is presented. We show that the developed feature-based measurement error can have a significant impact on the measurement accuracy and hence on process control and the diagnostic algorithms currently used in manufacturing. A feature-based error map and error compensation approach are also developed and presented. Simulations, experimental results and two industrial case studies illustrate the proposed method.     

板材剪切配送企业的物料需求模型与算法研究

概述了传统的MRP计算和板材剪切配送企业MRP计算的不同之处,提出板材剪切配送企业物料需求计算存在的问题;针对这些问题,借鉴制造行业物料需求计划的一般原理并结合板材剪切配送企业行业的特点,给出板材剪切配送企业物料需求模型,提出一种符合板材剪切配送企业特点的、有效的物料需求计算方法．