测量不确定度评定及应用

对测量误差和测量不确定度的基本概念作了介绍，并举例说明了测量不确定度A类和B类评定以及测量结果给出的方法，为测量不确定度评定提供参考。     

检测实验室测量不确定度评定

该文就土的含水率检测测量不确定度评定为例,阐述测量不确定度的评定方法与步骤,旨在与广大读者交流、学习,共同推广测量不确定度在工程实践中的应用,提高检测实验室的检测水平,使测量结果更完整,并与国际接轨。     

不稳定流河段流量测量不确定度评定探讨

河流流量不确定度评定与表示的内容很多,且测量方法和条件不同,其不确定度的估计方法也不相同,评定内容亦有所变化。介绍了测量不确定度概念和测量标准差的计算方法以及流量测量不确定度评定方法,指出采用贝塞尔法估计标准差难以适应不稳定流河段流量测量不确定度的评定,并提出采用阿伦方差替代贝塞尔法估计标准差,可获得较切合实际的不稳定流河段流量测量不确定度评定方法。     

外加剂减水率测量不确定度评定

随着科学技术的进步,外加剂已成为除水泥、粗细骨料、掺和料及水以外的第5种必备材料。减水率作为检测外加剂的一项重要指标,对判定外加剂品质的优劣起到重要的作用。根据检测数据的统计分析、计量器具的误差及仪器设备自身等实际情况进行类别判定,通过各因素的不确定度评定、合成、扩展,最终得出外加剂减水率不确定度,对外加剂减水率检测结果的可信度具有指导意义,为客观、公正评价外加剂的品质提供了有力保障。     

水力学模型试验两种参数的测量不确定度评定

将测量不确定度与水工模型试验结合起来,对水工模型试验测量中常见的2种检测参数(流量、流速)进行不确定度评定。评定结果表明:①对流量检测不确定度影响最大的参数是堰上水头,其次是堰宽、堰高。因此,在堰上水头的测量过程中应注意各操作步骤精度的控制,量水堰制作过程中应特别注意堰宽的控制。②对流速检测不确定度影响最大的是水体脉动及位置误差,由于水体脉动无法人为控制,因此应特别注意每次测量时测点位置的控制。     

钢弦式锚索测力计标定中的测量不确定度分析与评定

测量不确定度是目前对于误差分析的最新理解和阐述,用测量不确定度来表述测量获得结果的可信赖程度更具有实际意义。通过对钢弦式锚索测力计标定装置和标定方法的研究,分析了影响钢弦式锚索测力计标定结果的各项因素,进而对钢弦式锚索测力计标定结果的测量不确定度进行了分析和评定。     

水表示值误差测量结果的不确定度评定

测量不确定度是对测量结果可能产生误差的极限度量,是定量表示测量结果质量优劣并与测量结果关联的特征参数.依据<测量不确定度评定与表示>(JJG 1059-1999)计量技术规范,对水表示值误差测量结果进行不确定度评定.     

硝酸银滴定法测定水中氯化物的测量不确定度评定

根据GB/T11896-1989规定的测量步骤对水样中的氯化物进行了测定,对影响测定结果的各不确定度的来源进行了分析,并对一个水样的测定结果进行了不确定度评定.     

浅谈压力式温度计示值误差测量结果的不确定度评定

为了帮助试验人员深入了解压力式温度计的原理及作用,详细介绍了温度计示值误差测量结果的不确定度评定方法。影响压力式温度计示值误差结果的主要因素是,被检温度计的示值重复性、恒温槽温度不均匀性和恒温槽温场的波动。为了保证压力式温度计测量结果不确定度评定具有较高的可靠性,试验人员需要对影响评定可靠性的各种因素进行全面的分析,找出温度计示值的误差,从而确保温度计能够更好的被投入使用。     

测量不确定度分析及应用举例

依据 1 999年国家质量技术监督局计量司颁布的JJF 1 0 59- 1 999《测量不确定度评定与表示》 ,对测量误差和测量不确定度的基本概念作了简单介绍 ,并举例说明了测量不确定度A类和B类评定的方法。     

The Influence of Model Structure Uncertainty on Water Quality Assessment

Physically-based mathematical water quality models are known as potentially effective tools to simulate the temporal and spatial variations of water quality variables along rivers. Each model relies on specific sets of assumptions and equations to simulate the physico-biochemical processes, which influence on its simulation results. This paper aims to improve the insight in the uncertainties related to state–of–the–art river physico-biochemical water quality modelling. Sensitivity analysis is applied to the processes implemented in three most popular commercial software packages: MIKE11, InfoWorks RS and InfoWorks ICM. This is done for the Molse Neet river case study. Firstly, the physico-biochemical processes are screened to obtain a preliminary assessment on the critical processes and to determine the processes that require more detailed comparison. Then, local sensitivity analysis is carried out to specify the sensitive parameters and processes. Results show that the hydrodynamic results, heat transfer rate and reaeration simulations cause large differences in model simulation outputs for water temperature and dissolved oxygen concentrations. The ignorance of processes related to sediment transport, phytoplankton and bacteria has a significant influence on the higher values of organic matter and lower values of dissolved oxygen concentrations. The three models show consensus on the main pollutant sources explaining organic matter and nitrate concentrations, but disagree on the main factors explaining the DO concentrations.     

高填方下加筋土高挡墙实测变形分析

为了揭示位于“V”形沟谷中的某座3级加筋土挡墙的变形规律,在现场实测数据的基础上,重点分析了高填方下3级加筋土高挡墙墙面板位移、墙后填土体沉降、高填方下路面沉降以及挡墙下涵洞底部沉降在施工期间和竣工后的变化情况。结果表明:①加筋土挡墙墙面板的水平位移、竖向位移以及墙后填土体的沉降主要发生在施工期间,且数值都比较大,竣工后1~2 a的时间内,其变形趋于稳定,但总的累积变形较大,说明加筋土挡墙能够适应较大变形的填方工程,这是其优势所在;②在“V”形沟谷中采用高填方下加筋土高挡墙的结构形式能满足路面沉降要求,高填方下的涵洞也是安全的;③由于挡墙筋带的特殊性,使得形成的加筋土挡墙具有锚定板挡墙和土钉墙的某些优点,既能约束墙内土体的变形,又能作为整体很好地同周围“V”形沟谷变形相协调,使得填方内应力重分布,路面沉降变形平缓过渡,未产生明显差异沉降,使用效果良好。这种挡墙结构在山区公路铁路建设中具有广阔的应用前景,值得推广。     

乐滩水电站洪水系列一致性评价

通过对乐滩水电站上游的天生桥一级、天生桥二级、岩滩等水电站运行与调度方式的研究分析,并采用单、双累积曲线及入、出库洪水对比,由上游天生桥一级水电站至下游百龙滩水电站分时段依次评价各级电站建成前后,其下游特别是乐滩水电站洪水系列的一致性情况。并预评龙滩水电站建成后对下游洪水系列一致性的影响。     

气候变化对流域水资源影响评价中的不确定性问题

<正>确评价气候变化背景下的流域水资源是实现其可持续性开发利用的基础,气候变化对流域水资源影响的评价一般采取气候情景驱动水文循环模型的方法。由于气候系统和水文循环过程的复杂性,该方法在气候情景、水文循环模拟及评价过程中存在很大的不确定性。提高流域气候情景预测精度和完善影响评价模型是降低气候变化影响评价结果不确定性的主要方式。本文介绍了气候变化对流域水资源影响的一般评价方法,分析了影响评价结果不确定性的因素,并讨论了降低评价结果不确定性的方式。     

石虎塘航电枢纽工程土料分散性鉴定试验研究

利用双比重计、针孔、碎块和孔隙水可溶盐阳离子4种试验方法对南坪水库土样的分散性进行了研究.试验结果表明,土料K1以砂粒为主,K6、K8以粉粒为主;3组土料的钠含量小,可有效降低土料的分散性;这3组土样中K1、K6属于过渡性土,K8属于非分散性土.     

Uncertainty of the Agricultural Grey Water Footprint Based on High Resolution Primary Data

The water footprint has been established as an indicator to assess water use by a product. However, the grey component of the water footprint (GWF) has received the least focus compared to the green and blue components. In developing countries, the GWF estimation is restricted by the availability of data concerning crop practices. The various biophysical and socioeconomic settings configure a system difficult to standardize even for small areas. The objective of this study was to assess the GWF uncertainty due to primary data for the main greenhouse tomato production from Colombia. The GWF for N and P fertilizers and pesticides were estimated based on detailed crop information collected from 2010 to 2013. The uncertainty was evaluated by fitting univariate theoretical distributions to the empirical distributions of the pollutants’ GWFs. Growers applied on average 419.2 and 201.9 kg ha^?1 of N and P fertilizers per cycle, respectively. The average rates of application for fungicides and insecticides were 11.8 and 3.5 kg ha^?1, respectively. The average GWF for N and P fertilizers and pesticides were 79, 6182.1 and 223.2 m³ t^?1, respectively. The empirical distributions of the GWF for N fertilizer and pesticides were fitted to a lognormal distribution while for P fertilizer the Weibull distribution showed the best fit. The pesticides GWF showed the highest coefficient of variation (615.3%), however the results for N and P fertilizers were also high with values of 79.8 and 74.1%, respectively. Additional to the methodological choices involved in the GWF estimation, the primary data is a relevant uncertainty source, which should be considered for systems operating under unstandardized practices. The decision making process to regulate the pollutants losses from the agroecosystem, based on environmental assessments such as the GWF, should consider all sources of uncertainty and address its implications in a quantitatively form.     

长距离引水隧洞衬砌结构失事概率分析

针对长距离引水隧洞的工程实际．综合考虑地质条件以及围岩和衬砌结构参数的不确定性．采用随机有限元方法分析确定不同类型的衬砌结构在不同围岩下的失事概率,再由隧洞沿程岩性的分布概率得到衬砌结构的选型不匹配概率．最终由全概率公式确定隧洞沿程衬砌结构的失事概率．从而有针对性地提高隧洞衬砌结构设计的安全性和可靠性。     

聚羧酸减水剂分子量和官能团比例对其分散性能的影响

作为新型高性能减水剂,聚羧酸减水剂优越的分散性能取决于其分子结构可设计性。该文以改性大单体TPEG、丙烯酸(AA)和马来酸酐(MAD)等单体为主要原料合成聚羧酸减水剂,通过Ft-IR和GPC表征减水剂分子量、官能团类型和比例,并探讨减水剂在水泥净浆和砂浆中的分散性能。结果表明,以-COOH官能团为主导的减水剂减水性能较好,保坍性能则较差;以一定比例的-COOH和-COOR组成的官能团为主导的减水剂保坍性能较好,初始减水性能较差。随着n(-COOH)/n(-COOR)的不断增大,减水剂减水性能逐渐变差,保坍性能逐渐变好。