电梯能效测试不确定度评定

为了对电梯效能的不确定度进行评定,本文通过建立数学模型,制定不确定度的评定标准,并对标准进行合成,进而对不确定度进行评定,为电梯效能测试提供参考依据。     

氧气表测量不确定度评定

一切测量结果都不可避免地具有不确定度,测量不确定度的应用是测试计量领域的一大进步,它与传统的误差理论相比较,更加具有操作性,在计量技术机构建标复查及新建考核中,建标技术报告文件中常常会涉及不确定度的评定与验证,依据JJFl059－1999{测量不确定度评定与表示》,对一块25级25MPa分度值是O．5MPa的氧气表做一个扩展不确定度分析,以供参考。     

氧气表测量不确定度评定

一切测量结果都不可避免地具有不确定度,测量不确定度的应用是测试计量领域的一大进步,它与传统的误差理论相比较,更加具有操作性,在计量技术机构建标复查及新建考核中,建标技术报告文件中常常会涉及不确定度的评定与验证,依据JJF1059-1999<测量不确定度评定与表示>,对一块2.5级25MPa分度值是0.5MPa的氧气表做一个扩展不确定度分析,以供参考.     

铁矿石全铁含量测定结果的测量不确定度评定

文章分析了铁矿石全铁含量测定结果的不确定度来源,识别出不确定度分量,并对铁矿石样品全铁含量测定结果进行了不确定度评定。文章评定得出的铁矿石全铁含量结果的不确定度是实验室测定结果的不确定度,如果要获得交货批铁矿石全铁含量的测量不确定度,还要评定交货批铁矿石的取样和样品制备的不确定度。     

浅谈模拟式仪表测量不确定度的评定

测量不确定度的表示与评定，对从事校准或检测的技术人员来讲，如何对测量结果的不确定度进行科学合理的估计，给出评定结果是一项重要的工作。虽然国家技术监督部门提供了对测量不确定度评定的通用方法，但对具体的测量还要进行具体分析，给出更符合测量过程的测量不确定度评定。为此，针对模拟式仪表测量不确定度的评定谈点体会，便于同行交流探讨，不断完善，使测量不确定度的评定工作更加科学规范。１通常测量不确定度的评定包括７个部分： 即：概述，建立数学模型，确定各种不确定度来源，进行标准不确定度的分析，合成不确定度的评定…     

基于机动车检测中测量结果不确定度评定的研究

测量结果的准确性和可靠性在很大程度上取决于测量结果不确定度的大小,因此,合理评定测量结果的不确定度是检测中必须重视的问题。文章分析了机动车检测中测量结果不确定度的影响量,并对测量结果不确定度的评定方法进行了研究,得出了合成不确定度和扩展不确定度结果。     

实验室酸度计测量不确定度评定

文章主要介绍电计示值误差不确定度评定、数学模型、电计示值误差合成不确定度评定、仪器示值总误差测量结果不确定度评定。     

实验室酸度计测量不确定度评定

文章主要介绍电计示值误差不确定度评定、数学模型、电计示值误差合成不确定度评定、仪器示值总误差测量结果不确定度评定。     

信号发生器载波输出电平示值误差测量结果的不确定度评定

文章根据JJG 1059-1999《测量不确定度评定与表示》的不确定度评定原则,介绍了对信号发生器频率示值误差测量结果的不确定度评定。     

实木地板含水率不确定度评定

依据JJF1059--1999《测量不确定度评定与表示》及CNAS—GL05：2006（测量不确定度要求的实施指南〉对实木地板含水率的检测结果进行了不确定度的评定，对评定结果进行了分析。结果显示：干燥过程引起的不确定度是实木地板含水率不确定度评价的关键。     

On economic uncertainty,stock market predictability and nonlinear spillover effects

This paper uses a k-th order nonparametric Granger causality test to analyze whether firm-level, economic policy and macroeconomic uncertainty indicators predict movements in real stock returns and their volatility. Linear Granger causality tests show that whilst economic policy and macroeconomic uncertainty indices can predict stock returns, firm-level uncertainty measures possess no predictability. However, given the existence of structural breaks and inherent nonlinearities in the series, we employ a nonparametric causality methodology, as linear modeling leads to misspecifications thus the results cannot be considered reliable. The nonparametric test reveals that in fact no predictability can be observed for the various measures of uncertainty i.e., firm-level, macroeconomic and economic policy uncertainty, vis-à-vis real stock returns. In turn, a profound causal predictability is demonstrated for the volatility series, with the exception of firm-level uncertainty. Overall our results not only emphasize the role of economic and firm-level uncertainty measures in predicting the volatility of stock returns, but also presage against using linear models which are likely to suffer from misspecification in the presence of parameter instability and nonlinear spillover effects.     

Environmental uncertainty, supply chain relationship quality and performance

Environmental uncertainty is a fact of life in today's supply chains. In this paper we develop a model of environmental uncertainty, supply chain (SC) relationship quality and SC performance. We use data from the electronics sector in Ireland to test our model. Our results provide mixed support for the model, with the moderating role of both demand and supply uncertainty being supported, but technological uncertainty not supported. We reflect on these findings and suggest a research agenda based on our results.     

温度试验箱内部环境条件能不确定度要素分析

简要地讨论了对温度试验箱内部环境条件进行不确定度评定的要素特征。通过对要素的分析,给出了归集处理的原则。结合校准空载试验箱和带有负载试验箱环境条件测量的案例,逐条整理成为范本,用于分析结果以给出符合规范的不确定度评估。     

电缆质检中导体直流电阻测量不确定度探讨

根据国家的规定,应用在低压配电系统中的电线电缆,其导体电阻值不应大于标准规定值,为了保障运行安全,不管是电缆生产企业还是技术监督部门的检验机构,电缆导体电阻都是必须检验的项目,也是消费者(使用方)最关心的检验项目。测定不确定度是影响测定水平的重要指标,但是由于各种因素的影响,检测人员往往会忽略对于不确定度的评价,这就在一定程度上影响了检测结果的有效性与准确性。本文主要分析电缆质检中导体直流电阻测量的不确定度。     

Oil price uncertainty and movements in the US government bond risk premia

In this paper, we analyze the predictability of the movements of bond premia of US Treasury due to oil price uncertainty over the monthly period 1953:06 to 2016:12. For our purpose, we use a higher order nonparametric causality-in-quantiles framework, which in turn, allows us to test for predictability over the entire conditional distribution of not only bond returns, but also its volatility, by controlling for misspecification due to uncaptured nonlinearity and structural breaks, which we show to exist in our data. We find that oil uncertainty not only predicts (increases) US bond returns, but also its volatility, with the effect on the latter being stronger. In addition, oil uncertainty tends to have a stronger impact on the shortest and longest maturities (2- and 5-year), and relatively weaker impact on bonds with medium-term (3- and 4-year) maturities. Our results are robust to alternative measures of oil market uncertainty and bond market volatility.     

What effect does uncertainty have on the length of labor contracts?

The literature on duration of explicit labor contracts has suggested that increased uncertainty should be associated with shorter labor contracts. More recently, it has been argued that the effect of uncertainty on contract duration depends on the type of uncertainty involved. Specifically, if the uncertainty pertains to aggregate real shocks, then contract durations should increase as workers seek to insure themselves against the repercussions of such shocks. Using a sample of 1876 labor contracts signed during the period 1977–1988, this paper provides an empirical test of the foregoing hypothesis (known as the efficient risk sharing hypothesis). The paper presents results from estimation of a generalized-probit, simultaneous equation model, in which the dependent variables are contract length, indexation of the contract through a cost-of-living allowance, and the rate of wage change specified in the contract. The empirical findings confirm the efficient risk sharing hypothesis.     

U.S. uncertainty and Asian stock prices: Evidence from the asymmetric NARDL model

When uncertainty reduces spending among U.S. consumers, it may affect the bottom line stock performance of Asian producers that cater to their needs. Theory predicts that the impact of uncertainty will be asymmetrical: during the two phases of the business cycle, countercyclic shocks will outweigh procyclic shocks, resulting in phase-specific equilibrium price adjustments. We conjecture that relative to recessions, recoveries bring larger long-run price adjustments, a response to pent-up growth potential. This is an extension of existing theories, which predict that recoveries bring overshooting, a transient reaction to pent-up demand. We test for these asymmetric uncertainty effects on 11 Asian stock market indices over the 2000M08 – 2017M02 period. Our independent measures include the economic policy uncertainty index (EPU) of Baker, Bloom, and Davis (2016), the Chicago Board Options Exchange implied volatility index (VIX), and the financial uncertainty indicator (JLN) of Jurado, Ng, and Ludvigson (2015). To characterize asymmetry, we employ the nonlinear autoregressive distributed lag (NARDL) model of Shin, Yu, and Greenwood-Nimmo (2014), in which both short- and long-run nonlinearities are captured through positive and negative partial sum decompositions of the explanatory variable(s). Using the NARDL output, we test three hypotheses. The first, that increases in uncertainty (decreases in uncertainty) result in stock price drops (stock price rises), is broadly supported by our analysis. The second, that equilibrium adjustments following negative countercyclic uncertainty shocks exceed those following positive movements, is supported fully by the EPU analysis and partially by the VIX and JLN analyses. The third hypothesis, that recoveries are characterized by overshooting, is consistent only with the behavior of the Chinese stock responses to EPU and VIX shocks. Our results demonstrate the advantages of the NARDL model in characterizing asymmetry. They suggest that while long-run asymmetry is fairly consistent across countries, short-run asymmetry is more country-specific.     

Job security and employee well-being: Evidence from matched survey and register data

We examine the effects of establishment- and industry-level labor market turnover on employees' well-being. The linked employer-employee panel data contain both survey information on employees' subjective well-being and comprehensive register-based information on job and worker flows. We test for the existence of compensating wage differentials by explaining wages and job satisfaction with average uncertainties, measured by an indicator for a high excessive turnover (churning) rate. The results are consistent with the theory of compensating wage differentials, since high uncertainty increases real wages, but high uncertainty has no effect on job satisfaction while not controlling for wages.     

Nonnegativity constraints and intratemporal uncertainty in a multi-good life-cycle model

In the standard multi-good life-cycle consumption model (with intertemporal additive utility) the intratemporal relations between the marginal utilities of the different goods are deterministic. However, these deterministic identities will not usually be satisfied by the data. To avoid these deterministic relationships, we apply an approach which consists of introducing intratemporal uncertainty, and which is, in particular, interesting when additional nonnegativity constraints are present. We estimate some simple versions of the model with this so-called intratemporal uncertainty. The estimation results are, in general, in accordance with the theory, and most versions of the model are not rejected by Hansen and Singleton's misspecification test.