Noninformative priors for the two sample normal problem

Summary The paper considers two examples in the two sample normal problem and finds noniformative priors which satisfy (i) a criterion of matching asymptotically the posterior distribution function of a suitably normalized real-valued parameter of interest with the corresponding frequentist distribution function, and (ii) avoid the marginalization paradox. These two considerations lead to unique priors within certain classes for the two problems under consideration. In the first example, the prior turns out to be the one-at-a time reference prior of Berger and Bernardo (1992a, 1992b), while in the second example, the prior is outside the class of reference priors.     

Effects of an Inaccurate Sorting Procedure on Optimal Procurement and Production Decisions in a Remanufacturing System

Under the uncertainty of market demand and quality of returns, sorting prior to disassembly is effective for timely obtaining information about the remanufacturability of used products. In this article, we assume that the remanufacturable fraction of used products is a random variable and introduce an inaccurate sorting procedure of used products prior to disassembly. Then, three two-stage optimization models are formulated to maximize the expected profits of a remanufacturer in a single period with used products and/or new parts as inputs to meet the stochastic market demand. Moreover, the article provides a case study to explore the optimal decisions under different scenarios and analyzes the effects of parameters, such as the unit disassembly cost, unit sorting cost, and proportion of sorting errors. Finally, the results indicate that whether remanufacturing with sorting is more profitable than that without sorting mainly depends on the sorting accuracy and the relative value between disassembly cost and sorting cost. When considering or not considering a long lead time of new parts, the effects of sorting errors on procurement policies are different. A long lead time will result in lower expected profits. Finally, the diverse types of classification errors have different influences on procurement policies and corresponding expected profit.     

Information tradeoff

Summary A prior may be noninformative for one parameter at the cost of being informative for another parameter. This leads to the idea of tradeoff priors: priors that give up noninformativity for some parameters to achieve noninformativity for others. We propose a general framework where priors are selected by optimizing a functional with two components. The first component formalizes the requirement that the optimal prior be noninformative for the parameter of interest. The second component is a penalty term that forces the optimizing prior to be close to some target prior. Optimizing such a functional results in a parameterized family of priors from which a specific prior may be selected as the tradeoff prior. An important particular example of such functionals is provided by choosing the first term to be the marginal missing information for the parameter of interest (generalizing Bernardo’s notion of missing information) and the second term to be the relative entropy between the unknown prior and the Jeffreys prior. In this case we find a closed form expression for the tradeoff prior and we make explicit connections with the Berger-Bernardo prior. In particular, we show that under certain conditions, the Berger-Bernardo prior and the Jeffreys prior are special cases of the tradeoff prior. We consider several examples.     

借助准标样测算拉伸试验测量不确定度的方法

为了可靠地对拉伸试验相关检测项目的测量不确定度进行评定,借鉴国际硬度试验标准草案中测量不确定度评定的方法,介绍了一种以标准物质实测结果为基础的计算屈服强度Rp0.2、抗拉强度Rm和最大力总伸长率Agt的测量不确定度的方法。     

Probability matching priors for linear calibration

Summary In the linear calibration problem, a model is fit to paired observations arising from two measurement techniques, one known to be far more accurate (but also more expensive) than the other. The fitted model is then used with univariate observations from the less accurate technique to impute values from the more accurate one. The Bayesian paradigm emerges as attractive in this context, but the choice of an appropriate noninformative prior distribution has been controversial. In this paper we derive a class of such distributions, and provide sufficient conditions under which they lead to proper posterior densities. These priors, which we refer to asprobability matching priors, are designed to produce posterior credible intervals which are asymptotically identical to their frequentist counterparts. We provide details on the implementation of our procedure using sampling-based methods, and obtain significant simplifications over previous Bayesian approaches in this area. We compare the performance of several members of our prior class in the context of two illustrative examples.     

借助准标样测算夏比冲击试验测量不确定度的方法

为解决在测定材料冲击吸收功出现用户验收结果与出厂检验结果不一致的问题,提出了用准标样测算冲击试验测量不确定度的方法。这种方法可作为双方在进行冲击值比对分析时都能接受的评定方法。     

A new uncertainty importance measure

Uncertainty in parameters is present in many risk assessment problems and leads to uncertainty in model predictions. In this work, we introduce a global sensitivity indicator which looks at the influence of input uncertainty on the entire output distribution without reference to a specific moment of the output (moment independence) and which can be defined also in the presence of correlations among the parameters. We discuss its mathematical properties and highlight the differences between the present indicator, variance-based uncertainty importance measures and a moment independent sensitivity indicator previously introduced in the literature. Numerical results are discussed with application to the probabilistic risk assessment model on which Iman [A matrix-based approach to uncertainty and sensitivity analysis for fault trees. Risk Anal 1987;7(1):22–33] first introduced uncertainty importance measures.     

参考信号频率自调整的数字相敏检波器算法的研究

本文提出了一种不需要外接同频参考信号的数字相敏检波器算法。该算法首先提取计算机产生的参考信号与被测信号频率的差值，然后根据该差值调整参考信号的频率直到满足要求。本文还讨论了数字相敏检波器的幅频特性，仿真试验表明理论分析与实际结果是一致的。该算法可以用于同频参考信号不能获得时正弦信号的幅度和相位测量。     

支持连接的高可用性网管系统参考模型

指出了网络管理环境中现有的高可用性系统的不足,提出了可用性连接和高可用管理域的概念,给出了支持连接的高可用性网管系统参考模型。     

A Bayesian analysis of classical hypothesis testing

Summary The procedure of maximizing the missing information is applied to derive reference posterior probabilities for null hypotheses. The results shed further light on Lindley’s paradox and suggest that a Bayesian interpretation of classical hypothesis testing is possible by providing a one-to-one approximate relationship between significance levels and posterior probabilities.     

The Reference Gauge technique for static expansion ratios—Applied to NPL medium vacuum standard SEA3

Static expansion pressure standards are typically characterised in terms of the ratio between the density of an expanded sample of gas and that of an initial sample. For standards that perform a series of expansions through several system vessels most of the existing techniques to measure this expansion ratio involve disturbance to the system. They usually also involve operation with higher pressures and with valve sequences that are not encountered under normal operational conditions, thereby introducing the risk of systematic errors. A modification of the Reference Gauge technique for expansion ratios is described which has none of these disadvantages. The technique is described with reference to the medium vacuum standard SEA3 at the UK National Physical Laboratory.     

Particle size measurement of reference particle candidates and uncertainty region of count and mass based cumulative distribution

In order to confirm reliable particle size measurement technique and to prepare standard reference particles for calibrating particle size measurement devices, uncertainty region of count and mass based size distribution have been theoretically examined. The uncertainty region of count base cumulative size distribution is smaller than that of the mass base cumulative distribution.The uncertainty region of count base cumulative size distribution is nearly constant over wide range of particle diameter and the region is nearly constant for sample size greater than about 20,000.On the other hand, the uncertainty region of mass base cumulative distribution increases with the increase of particle diameter.The reliability of theoretical uncertainty region is confirmed by the experimental data of particle size measurement.     

冰冻人血清尿酸标准物质的研制

介绍了冰冻人血清尿酸标准物质的研制方法.采用液相色谱/同位素稀释质谱法(LC/ID-MS)对该标准物质进行了定值研究、均匀性检验和稳定性检验.研究结果表明,冰冻人血清尿酸标准物质定值结果为55.88 mg/kg,扩展不确定度为0.74 mg/kg,其均匀性和稳定性检验结果均符合国家一级标准物质的技术要求.     

高效液相色谱测定防老剂D纯度的不确定度评定

建立了高效液相色谱法测定防老剂D纯度的数学模型并推导出不确定度计算公式；通过对公式中各变量的分析，计算了各变量的不确定度，最后计算出合成不确定度。     

An Inductively Coupled Plasma Source for the Gaseous Electronics Conference RF Reference Cell

In order to extend the operating range of the GEC RF Reference Cell, we developed an inductively coupled plasma source that replaced the standard parallel-plate upper-electrode assembly. Voltage and current probes, Langmuir probes, and an 80 GHz interferometer provided information on plasmas formed in argon, chlorine, and nitrogen at pressures from 0.1 Pa to 3 Pa. For powers deposited in the plasma from 20 W to 300 W, the source produced peak electron densities between 10¹⁰/cm³ and 10¹²/cm³ and electron temperatures near 4 eV. The electron density peaked on axis with typical full-width at half maximum of 7 cm to 9 cm. Discharges in chlorine and nitrogen had bimodal operation that was clearly evident from optical emission intensity. A dim mode occurred at low power and a bright mode at high power. The transition between modes had hysteresis. After many hours of high-power operation, films formed on electrodes and walls of one Cell. These deposits affected the dim-to-bright mode transition, and also apparently caused generation of hot electrons and increased the plasma potential.     

具有共同分量的相关数据的加权平均

对比不相关数据的加权平均法,讨论了对具有共同分量的一组相关数据的加权平均法。分析了比对数据的相关性,将相关数据的不确定度分解为共同分量与不相关分量的组合。提出了具有较好可操作性的估计比对数据溯源链共同分量不确定度的简单方法。结论为加权平均应以不相关分量的不确定度为权重因素;共同分量的不确定度是“固有”的,不随参与平均计算的数据数量的增加而减小;忽略数据相关性,不仅影响加权平均的权重,进而影响平均值,也会导致平均值不确定度计算结果偏小。以压力比对为例分析了共同分量的不确定度的评定以及不同取值结果的差异。     

无磷洗衣粉中磷标准物质的研制

采用上海白猫有限公司提供的无磷洗衣粉配方,以间隙喷粉进科、小型釜反应的工艺方式制备标准物质。用F－t检验法证明其均匀性良好;由7家单位的8个实验室采用不同的方法共同协作定值,共64个数据,经统计检验给出P2O5的标准值和不确定度;经过一年半的稳定性检没,稳定性良好。     

Copper Oxide Precipitates in NBS Standard Reference Material 482

Copper oxide has been detected in the copper containing alloys of NBS Standard Reference Material (SRM) 482. This occurrence is significant because it represents heterogeneity within a standard reference material that was certified to be homogeneous on a micrometer scale. Oxide occurs as elliptically to spherically shaped precipitates whose size differs with alloy composition. The largest precipitates occur in the Au20-Cu80 alloy and range in size from submicrometer up to 2 μm in diameter. Precipitates are observed using light microscopy, electron microscopy, and secondary ion mass spectrometry (SIMS). SIMS has demonstrated that the precipitates are present within all the SRM 482 wires that contain copper. Only the pure gold wire is precipitate free. Initial results from the analysis of the Au20-Cu80 alloy indicate that the percentage of precipitates is less than 1 % by area. Electron probe microanalysis (EPMA) of large (2 μm) precipitates in this same alloy indicates that precipitates are detectable by EPMA and that their composition differs significantly from the certified alloy composition. The small size and low percentage of these oxide precipitates minimizes the impact that they have upon the intended use of this standard for electron probe microanalysis. Heterogeneity caused by these oxide precipitates may however preclude the use of this standard for automated EPMA analyses and other microanalysis techniques.     

高校资料室建设中存在的问题与对策

文章论述了高校院系资料室建设的重要性与必要性，同时也从业务、采购、管理、设施、人员素质等方面原因进行了分析，进而提出了一系列改进高校院系资料室建设的措施。