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水表使用误差的分析及对策 被引量:3
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作者 张霁 李延红 赵普 《沈阳建筑工程学院学报》 2001年第2期134-137,共4页
从水表的质量、现场安装条件、水表口径选择、管道水质等因素 ,分析了误差变化规律 ,研究了水表误差变化机理 ,并从合理选型、加强质量检验、正确安装、改善水质、对水表使用过程中的误差变化跟踪考核、加强水表强制检定工作等方面提出... 从水表的质量、现场安装条件、水表口径选择、管道水质等因素 ,分析了误差变化规律 ,研究了水表误差变化机理 ,并从合理选型、加强质量检验、正确安装、改善水质、对水表使用过程中的误差变化跟踪考核、加强水表强制检定工作等方面提出了所应采取的措施 ,控制其误差变化 。 展开更多
关键词 水表 使用误差 误差分析
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地理坐标系下GPS定位误差的定量研究 被引量:4
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作者 郭岩冰 缪玲娟 +1 位作者 李传军 张希 《北京理工大学学报》 EI CAS CSCD 北大核心 2020年第4期416-420,共5页
针对目前对使用伪距的GPS定位误差的定量分析仍然不够精确的问题,本文分2种情况在东北天地理坐标系下对GPS定位误差进行了进一步分析:当使用全部可见卫星进行定位时,通过为不同纬度设置相应参数明显改进了GPS定位误差表达式;当选择4颗... 针对目前对使用伪距的GPS定位误差的定量分析仍然不够精确的问题,本文分2种情况在东北天地理坐标系下对GPS定位误差进行了进一步分析:当使用全部可见卫星进行定位时,通过为不同纬度设置相应参数明显改进了GPS定位误差表达式;当选择4颗最优卫星进行定位时,针对更加实际的情况首次得出了GPS定位误差表达式.从而给出了这2种情况下各向定位误差之间的关系.在用户测距误差标准差σURE已知的情况下,根据提出的公式能够更加准确地估计GPS各向定位误差的标准差.通过SPIRENT卫星信号模拟器生成赤道、北纬45°和北极点处的卫星信号,验证了所提出公式的精确性. 展开更多
关键词 使用伪距的GPS定位误差 全部可见卫星 GPS定位误差表达式 4颗最优卫星 GPS各向定位误差的标准差
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Real time remaining useful life prediction based on nonlinear Wiener based degradation processes with measurement errors 被引量:24
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作者 唐圣金 郭晓松 +3 位作者 于传强 周志杰 周召发 张邦成 《Journal of Central South University》 SCIE EI CAS 2014年第12期4509-4517,共9页
Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degrad... Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item's individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction. 展开更多
关键词 remaining useful life Wiener based degradation process measurement error nonlinear maximum likelihood estimation Bayesian method
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Content based error resilience coding using redundant coding, reference frame modification, and mode decision
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作者 徐巍炜 蒋荣欣 +1 位作者 田翔 陈耀武 《Journal of Central South University》 SCIE EI CAS 2014年第11期4199-4209,共11页
Quality degradation occurs during transmission of video streaming over the error-prone network. By jointly using redundant slice, reference frame selection, and intra/inters mode decision, a content and end-to-end rat... Quality degradation occurs during transmission of video streaming over the error-prone network. By jointly using redundant slice, reference frame selection, and intra/inters mode decision, a content and end-to-end rate-distortion based error resilience method is proposed. Firstly, the intra/inter mode decision is implemented using macro-block(MB) refresh, and then redundant picture and reference frame selection are utilized together to realize the redundant coding. The estimated error propagation distortion and bit consumption of refresh MB are used for the mode and reference frame decision of refresh MB. Secondly, by analyzing the statistical property in the successive frames, the error propagation distortion and bit consumption are formulated as a function of temporal distance. Encoding parameters of the current frame is determined by the estimated error propagation distortion and bit consumption. Thirdly, by comparing the rate-distortion cost of different combinations, proper selection of error resilience method is performed before the encoding process of the current frame. Finally, the MB mode and bit distribution of the primary picture are analyzed for the derivation of the texture information. The motion information is subsequently incorporated for the calculation of video content complexity to implement the content based redundant coding. Experimental results demonstrate that the proposed algorithm achieves significant performance gains over the LA-RDO and HRP method when video is transmitted over error-prone channel. 展开更多
关键词 error resilience coding redundant picture macro-block(MB) refresh reference frame selection error propagation distortion
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