Accuracy estimation of site coordinates derived from GNSS-observations by non-classical error theory of measurements

The velocities of tectonic plates derived from GNSS time series are regularly used as input data for geophysical models. However, as shown by numerous researches, the coordinates time series contain residual errors of a systematic nature, which can significantly affect the reliability of the obtained velocity estimates. This research shows that using non-classical error theory of measurement(NETM)for processing GNSS time series allows detecting the presence of weak, not removed from GNSS processing, sources of systematic errors. Based on the coordinate time series of selected permanent GNSS stations in Europe, we checked the empirical distributions of errors by the NETM on G. Jeffries’ recommendations and on the principles of the theory of hypothesis tests according to Pearson’s criterion. It is established that the obtained coordinates time series of GNSS-stations only partially confirm the hypothesis of their conformity to the normal Gaussian distribution law, and this may be the main reason for their unrepresentative classification. In the future, it is necessary to identify and take into account the causes of residual errors that distort the real distribution of the results of the GNSS time series.

Measurement Uncertainty Evaluation of Conicity Error Inspected on CMM

The cone is widely used in mechanical design for rotation, centering and fixing. Whether the conicity error can be measured and evaluated accurately will directly influence its assembly accuracy and working performance. According to the new generation geometrical product specification（GPS）, the error and its measurement uncertainty should be evaluated together. The mathematical model of the minimum zone conicity error is established and an improved immune evolutionary algorithm（IlEA） is proposed to search for the conicity error. In the IIEA, initial antibodies are firstly generated by using quasi-random sequences and two kinds of affinities are calculated. Then, each antibody clone is generated and they are self-adaptively mutated so as to maintain diversity. Similar antibody is suppressed and new random antibody is generated. Because the mathematical model of conicity error is strongly nonlinear and the input quantities are not independent, it is difficult to use Guide to the expression of uncertainty in the measurement（GUM） method to evaluate measurement uncertainty. Adaptive Monte Carlo method（AMCM） is proposed to estimate measurement uncertainty in which the number of Monte Carlo trials is selected adaptively and the quality of the numerical results is directly controlled. The cone parts was machined on lathe CK6140 and measured on Miracle NC 454 Coordinate Measuring Machine（CMM）. The experiment results confirm that the proposed method not only can search for the approximate solution of the minimum zone conicity error（MZCE） rapidly and precisely, but also can evaluate measurement uncertainty and give control variables with an expected numerical tolerance. The conicity errors computed by the proposed method are 20%-40% less than those computed by NC454 CMM software and the evaluation accuracy improves significantly.

Estimation of Glacier Melt Water Contribution for Human Consumption in the Royal Andes Considering Temperature Measurement Errors

Glaciers from the West side of the Royal Andes are an important source of fresh water for some of the most important Bolivian cities like El Alto. Temperature is an important datum for hydrological modelling and for glacier melt estimation. All temperature measurement devices have some degree of uncertainty due to systematic errors;thus, any temperature measurement has some errors. It is important to estimate the influence of such errors on the results from hydrological models and the estimation of melt water. The present study estimates the melt water contribution from the glaciers Tuni and Huayna West as a source of water supply for human consumption of El Alto considering the errors from temperature measurements. The hydrologic response of the basins was simulated with a hydrologic model. The glacier melt contribution was estimated as the difference between the discharge from the current scenario (with glaciers) and the discharge from a scenario without glaciers. Several volumes of melt water were estimated considering the temperature measurement and its possible errors. The uncertainty of such melt water volume was addressed by performing a Monte Carlo analysis of the possible melt water. The melt water contribution from glacier Tuni and Huayna West during the hydrologic year 2011-2012 was between 1.37 × 106 m3 and 1.72 × 106 m3. Such water volume is enough to meet the yearly water demand of between 6.81% and 8.55% of El Alto.

Quantitative feedback theory and zero phase error tracking control combined robust control for radar truck leveling simulator

Radar leveling system is the key equipment for improving the radar mobility and survival capability. A combined quantitative feedback theory (QFT) controller is designed for the radar truck leveling simulator in this paper, which suffers from strong nonlinearities and system parameter uncertainties. QFT can reduce the plant uncertainties and stabilize the system, but it fails to obtain high-precision tracking. This drawback can be solved by a robust QFT control scheme based on zero phase error tracking control (ZPETC) compensation. The combined controller not only possesses high robustness, but greatly improves the system performance. To verify the effiectiveness and the potential of the proposed controller, a series of experiments have been carried out. Experimental results have demonstrated its robustness against a large range of parameters variation and high tracking precision performance, as well as its capability of restraining the load coupling among channels. The combined QFT controller can drive the radar truck leveling platform accurately, quickly and stably.

Research on Consistency Judgement of Indication Error for Calibration Result of Humidity Sensor in Meteorology

In order to solve the lack of relevant evaluation research on the accuracy of HMP155A humidity sensor calibration results in the past, this paper designs the corresponding experimental scheme, and obtains the corresponding calibration results according to the experimental scheme;Then the measurement uncertainty of the indication error in the calibration results is evaluated by GUM, and the corresponding extended uncertainty U95 is obtained. Finally, according to the requirements of JJF1094-2016 characteristic evaluation of measuring instruments, combined with the calibration results and the actual situation of U95, the conformity of the indication error of calibration is determined. The result is that each calibration point of the sensor meets the requirements of conformity determination and is within the qualified range. This research effectively makes up for the blank of the previous research on the conformity determination of the indication error of the calibration results and has strong theoretical and practical significance.

“数形结合”——测量及不确定度教学模式的改革与研究

理解测量的不确定度是大学物理实验课程一项重要的教学目标。在大学物理实验绪论课中,准备了两个版本的不确定性教学方式:即有无测量数据的图形化展示。课程结束后,对学生进行测试,研究数据的图形化展示是否能够提高学生对不确定度的理解。结果表明,有图形展示的班级学生比没有图形展示的班级学生得分更高。图形表示有助于数据的可视化,在进行测量数据分析时减少了学生的认知负荷,因此应该在教学中积极推广使用。

电池热释放烟气分析系统的校准

提出电池热释放烟气分析系统的校准方法。采用氧气、二氧化碳、一氧化碳、氢气、甲烷标准物质进行试验,选取示值误差、重复性、响应时间、零点漂移和量程漂移作为校准项目,建议计量技术指标:每种气体在量程内,示值误差为±3.0%,重复性不大于1.5%,响应时间不大于30 s,零点漂移和量程漂移均为±2.0%。通过校准实例对校准方法进行验证,验证结果表明该校准方法切实可行,可为该类设备计量技术规范的制订提供参考。

曲轴综合测量机几何误差建模及敏感性分析

为提高曲轴综合测量机测量精度,针对其几何误差元素多,逐一进行补偿工作量大、过程繁琐等问题,基于多体系统理论和齐次坐标变换建立曲轴综合测量机的几何误差模型,采用Sobol敏感性分析方法进行分析,识别出对测量精度影响较大的关键几何误差项。通过对曲轴综合测量机随动测板不同位置处的误差元素敏感性系数进行分析计算,从21项几何误差中识别出10项对曲轴综合测量机测量精度影响较大的关键项,为合理经济地提高曲轴综合测量机测量精度提供依据。

Uncertainty analysis of forest carbon sink forecast with varying measurement errors:a data assimilation approach

Aims Accurate forecast of ecosystem states is critical for improving natural resourcemanagement and climate change mitigation.Assimilating observed data into models is an effective way to reduce uncertainties in ecological forecasting.However,influences ofmeasurement errors on parameter estimation and forecasted state changes have not been carefully examined.This study analyzed the parameter identifiability of a process-based ecosystem carbon cycle model,the sensitivity of parameter estimates and model forecasts to the magnitudes of measurement errors and the information contributions of the assimilated data to model forecasts with a data assimilation approach.Methods We applied a Markov Chain Monte Carlo method to assimilate eight biometric data sets into the Terrestrial ECOsystemmodel.The data were the observations of foliage biomass,wood biomass,fine root biomass,microbial biomass,litter fall,litter,soil carbon and soil respiration,collected at the Duke Forest free-air CO_(2)enrichment facilities from 1996 to 2005.Three levels ofmeasurement errorswere assigned to these data sets by halving and doubling their original standard deviations.Important Findings Results showed that only less than half of the 30 parameters could be constrained,though the observations were extensive and themodelwas relatively simple.Highermeasurement errors led to higher uncertainties in parameters estimates and forecasted carbon(C)pool sizes.The longterm predictions of the slow turnover pools were affected less by the measurement errors than those of fast turnover pools.Assimilated data contributed less information for the pools with long residence times in long-term forecasts.These results indicate the residence times of C pools played a key role in regulating propagation of errors from measurements to model forecasts in a data assimilation system.Improving the estimation of parameters of slowturnover C pools is the key to better forecast long-term ecosystem C dynamics.

基于OBE-BOPPPS的误差理论与测量平差基础课程教学改革研究

为推动课程教学质量的持续提升,本文结合我校误差理论与测量平差基础课程教学存在的问题及工程教育专业认证时专家提出的意见,基于OBE-BOPPPS教育理念与模式,从教学目标、内容与方法、教学方式和考核方式等方面对毕业要求的支撑关系进行改革与实践。达成度指标分析表明,该模式有助于解决教学过程中学生参与度低与学习目标不明确等问题,提高教学质量。

基于物理水平基准的组合式高程测量方法

针对空间坐标点相对于测量基准的高程测量准确性问题,提出一种基于物理水平基准的组合式高程测量方法。利用激光三角测量原理及其测量光路的几何特性,搭建了物理水平基准的高程测量系统,在朗伯散射光场中,分析了倾角变化对激光光能质心偏移量的影响,建立了相应的误差修正模型,利用倾角传感器实现了高程测量的倾角误差补偿,自主研制了标定平台对本文提出的高程测量系统进行标定验证试验。结果表明:本文提出的组合式高程测量方法能够在500 mm测量量程下将重复性测量误差控制在±20μm的波动范围内,相较于单一激光位移传感器测量方式,其组合式高程测量误差波动量大幅度降低,能够适应空间坐标点在任意姿态下的精准测量,有效改善激光位移传感器在高程测量领域的性能,使其测量结果更为真实有效。

基于特征样件在机测量的机床偏摆误差辨识及其不确定度评估

机床几何误差的测量和补偿可以提高机床的加工精度。随着机床在机测量技术的发展,在机测量特征样件辨识几何误差逐渐应用到机床的精度检查中。文章提出了一种基于特征样件在机测量的机床偏摆误差辨识方法,应用激光干涉跟踪仪验证了辨识方法的正确性,分析了安装误差对于偏摆误差辨识的影响。应用自适应蒙特卡洛法结合误差椭圆评估了在机测量特征样件辨识偏摆误差的不确定度,且应用GUM法验证了不确定度评估方法。特征样件在机测量偏摆误差的方法能够获得可接受的几何误差辨识精度,可作为传统的基于激光干涉测量技术的几何误差辨识的替代方法,非常适合机床精度的周期性检查,来保持机床加工质量的一致性。

压力表计量的不确定度评价与校准率的研究

由于指针式压力表性能稳定、可靠性高,在工业生产中得到了广泛的使用。本文通过对指针式压力计人工检定的不确定度进行分析与评估,对其在检表过程中可能产生的各种影响因素的分析与评价,对其产生的各种不确定度进行分析,并对各不确定度进行计算,最终获得综合不确定度评价结果。同时,通过人工操纵校准设备对压力表的打压速率进行试验,探索校准过程中各校准点间的压力变化规律,获得合适的升降速度。本文研究成果能够真实地反映出被测数据的误差变化幅度,有助于正确判定测试结果的准确性,并为实现自动压降速度的自动控制提供一定的依据。

无创自动测量血压计静态压力示值误差测量结果的不确定度评定

电子血压计作为测量人体血压最常见的设备之一,不确定度的评定是判定测量值准确与否的重要指标。本文介绍示波法原理的无创自动测量血压计静态压力示值误差测量结果的不确定度评定和表达方法。

GUM与MCM评定雨量传感器不确定度对比研究

以SL3-1型双翻斗雨量传感器的校准结果为例,开展评定雨量传感器不确定度对比研究。首先,对雨量传感器结构、工作原理以及试验方案进行分析。然后,分别采用《测量不确定性的表达指南》(GUM)和蒙特卡洛法(MCM)对雨量传感器误差的测量不确定度进行分析与评定,发现MCM比GUM具有更完整的理论依据,能有效地简化不确定度的评定流程等。最后,根据《用蒙特卡洛法评定测量不确定度》方法,用MCM对GUM进行适用性验证,发现GUM不适合翻斗式雨量传感器误差的测量不确定度的评定。研究结果显示,评定翻斗式雨量传感器误差的测量不确定度时,采用MCM更合适,可提高雨量传感器测量结果的可信程度。该研究有效突破以往研究中仅依靠GUM评定雨量传感器不确定度,导致结果可靠性不高的现状。该研究对于观测数据的合理应用、仪器的改进与研发等方面有着重要的理论和应用价值。

千分尺示值误差不确定度评定及在形位误差测量中的应用

几何量测量在电机研发、生产及制造中均广泛存在,而分析测量结果的质量如何,测量不确定就是一个衡量尺度,本文首先对标准不确定的A类及B类评定方法及流程进行介绍,再通过实例对日常检测中使用的外径千分尺示值误差的不确定度进行了计算,并对外径千分尺两点法测量圆度误差进行了探究。

基于显微镜标尺法的碳纤维复合材料孔隙率测量不确定度评定

使用显微镜标尺法对碳纤维复合材料孔隙率试验结果进行测量不确定度评定,对不确定度来源进行分析,对各个不确定度分量进行计算。结果表明:影响不确定度的主要因素是孔隙格子数的测量重复性。

钢丝绳网紧固件镀锌层厚度测量不确定度评定

根据JJF 1059.1—2012及GB/T 6462—2005对影响钢丝绳网紧固件镀锌层厚度的不确定度因素进行分析,评定了合成不确定度和扩展不确定度,通过人员比对分析的方法确定归一化偏差,给出了评定意见。

因瓦水准标尺示值误差的不确定度评定

因瓦水准标尺是水准测量仪器的组成部分,也是传递国家长度标准的载体。对水准标尺进行计量检定是保证量值传递的可靠手段。针对二等标准金属线纹尺检定因瓦水准标尺,需要不确定度的评定来评价检测结果的质量。根据《水准标尺检定规程》JJG 8—1991要求,按照不确定度评定理论,使用GUM法,根据不确定度传播定律及不确定度评定步骤,给出了因瓦水准标尺的示值误差的不确定度。结果表明采用二等标准金属线纹尺检定因瓦水准标尺满足规范要求。

自动控制中的压力表计量检定分析

阐述压力表计量检定的特点和流程,压力表检定过程中的问题与应对策略,包括滞针和跳针问题、轻敲位移问题、指针不归零问题、测量误差较大及应对措施。