In order to</span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> reduce the influence of nonlinear </span><span...In order to</span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> reduce the influence of nonlinear </span><span style="font-family:Verdana;">characteristic</span><span style="font-family:Verdana;"> and temperature on the measuring accuracy of </span><span style="font-family:Verdana;">inclinometer</span><span style="font-family:Verdana;">, the application of </span><span style="font-family:Verdana;">polynomial</span><span style="font-family:Verdana;"> fitting principle to compensate </span><span style="font-family:Verdana;">the</span><span style="font-family:Verdana;"> measuring error of </span><span style="font-family:Verdana;">inclinometer</span><span style="font-family:Verdana;"> is studied. According to the analysis of the experimental data of inclinometer, a polynomial model of the nonlinear error and the measured value is constructed, and then the relation between the coefficient of the polynomial model and the temperature is obtained by fitting, and </span><span style="font-family:Verdana;">finally</span><span style="font-family:Verdana;"> the function of the measurement error of inclinometer on the measured inclination and temperature is obtained. The results show that this method is feasible and effective, which can not only reduce the influence of </span><span style="font-family:Verdana;">temperature,</span><span style="font-family:Verdana;"> but also correct its nonlinear error.展开更多
An h-adaptive meshless method is proposed in this paper. The error estimation is based on local fit technology, usually confined to Voronoi Cells. The error is achieved by comparison of the computational results with ...An h-adaptive meshless method is proposed in this paper. The error estimation is based on local fit technology, usually confined to Voronoi Cells. The error is achieved by comparison of the computational results with smoothed ones, which are projected with Taylor series. Voronoi Cells are introduced not only for integration of potential energy but also for guidance of refinement. New nodes are placed within those cells with high estimated error. At the end of the paper, two numerical examples with severe stress gradient are analyzed. Through adaptive analysis accurate results are obtained at critical subdomains, which validates the efficiency of the method.展开更多
The principle of planc-to-plane perpendicularity measuring with coordinate measuring machine （CMM） is described and the main factors that influence the measuring precision are analyzed. The minimum condition method ...The principle of planc-to-plane perpendicularity measuring with coordinate measuring machine （CMM） is described and the main factors that influence the measuring precision are analyzed. The minimum condition method is adopted to eliminate the fitting error of the datum plane. In order to diminish the length error of the object plane, the tactics of measuring some part of the plane and then scale to the whole plane is employed. With large quantity of measuring experiments on fiat plates, the most appropriate number of points in measuring a plane is determined to reduce the sampling error.展开更多
Two error data fitting schemes,interpolation and least square fitting are explored: the least-square fitting scheme, which is simple in equation and bettr result in compensation, is strongly suggested Then an so-call...Two error data fitting schemes,interpolation and least square fitting are explored: the least-square fitting scheme, which is simple in equation and bettr result in compensation, is strongly suggested Then an so-called “Punishing compensation” scheme is exploited, By means of proportioning,subtacting and recursive compensation, the solid modeling errors may be grealy cut down. Appropriate scheme should be selected according to solid modeling precision requirement.展开更多
传统基于相干积分结果最大值检测的开环信号到达时间(Time of Arrival,TOA)估计方法性能受限于采样率,TOA估计分辨率无法突破采样间隔限制。针对这一问题,提出一种基于定时曲线匹配拟合的开环TOA估计方法,通过将相干积分结果与定时曲线...传统基于相干积分结果最大值检测的开环信号到达时间(Time of Arrival,TOA)估计方法性能受限于采样率,TOA估计分辨率无法突破采样间隔限制。针对这一问题,提出一种基于定时曲线匹配拟合的开环TOA估计方法,通过将相干积分结果与定时曲线进行最优匹配拟合来估计信号到达时间。以直接序列扩频信号三角形定时曲线为例,首先基于相干积分结果和定时曲线构建拟合误差平方和模型,然后采用牛顿迭代法,通过最小化拟合误差平方和,实现对信号到达时间的最小二乘估计,最后评估了检测信噪比和采样率对估计精度的影响。与传统方法相比,所提方法能够将TOA估计误差的标准差降低50%~97%。该方法可推广应用于其他类型定时曲线。展开更多
文摘In order to</span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> reduce the influence of nonlinear </span><span style="font-family:Verdana;">characteristic</span><span style="font-family:Verdana;"> and temperature on the measuring accuracy of </span><span style="font-family:Verdana;">inclinometer</span><span style="font-family:Verdana;">, the application of </span><span style="font-family:Verdana;">polynomial</span><span style="font-family:Verdana;"> fitting principle to compensate </span><span style="font-family:Verdana;">the</span><span style="font-family:Verdana;"> measuring error of </span><span style="font-family:Verdana;">inclinometer</span><span style="font-family:Verdana;"> is studied. According to the analysis of the experimental data of inclinometer, a polynomial model of the nonlinear error and the measured value is constructed, and then the relation between the coefficient of the polynomial model and the temperature is obtained by fitting, and </span><span style="font-family:Verdana;">finally</span><span style="font-family:Verdana;"> the function of the measurement error of inclinometer on the measured inclination and temperature is obtained. The results show that this method is feasible and effective, which can not only reduce the influence of </span><span style="font-family:Verdana;">temperature,</span><span style="font-family:Verdana;"> but also correct its nonlinear error.
基金Project supported by the National Natural Science Foundation of China (No. 50175060).
文摘An h-adaptive meshless method is proposed in this paper. The error estimation is based on local fit technology, usually confined to Voronoi Cells. The error is achieved by comparison of the computational results with smoothed ones, which are projected with Taylor series. Voronoi Cells are introduced not only for integration of potential energy but also for guidance of refinement. New nodes are placed within those cells with high estimated error. At the end of the paper, two numerical examples with severe stress gradient are analyzed. Through adaptive analysis accurate results are obtained at critical subdomains, which validates the efficiency of the method.
基金sponsored by the Special Research Fund for Young Teachers of Universities in Shanghai under Grant No.gjd-07048
文摘The principle of planc-to-plane perpendicularity measuring with coordinate measuring machine （CMM） is described and the main factors that influence the measuring precision are analyzed. The minimum condition method is adopted to eliminate the fitting error of the datum plane. In order to diminish the length error of the object plane, the tactics of measuring some part of the plane and then scale to the whole plane is employed. With large quantity of measuring experiments on fiat plates, the most appropriate number of points in measuring a plane is determined to reduce the sampling error.
文摘Two error data fitting schemes,interpolation and least square fitting are explored: the least-square fitting scheme, which is simple in equation and bettr result in compensation, is strongly suggested Then an so-called “Punishing compensation” scheme is exploited, By means of proportioning,subtacting and recursive compensation, the solid modeling errors may be grealy cut down. Appropriate scheme should be selected according to solid modeling precision requirement.
文摘传统基于相干积分结果最大值检测的开环信号到达时间(Time of Arrival,TOA)估计方法性能受限于采样率,TOA估计分辨率无法突破采样间隔限制。针对这一问题,提出一种基于定时曲线匹配拟合的开环TOA估计方法,通过将相干积分结果与定时曲线进行最优匹配拟合来估计信号到达时间。以直接序列扩频信号三角形定时曲线为例,首先基于相干积分结果和定时曲线构建拟合误差平方和模型,然后采用牛顿迭代法,通过最小化拟合误差平方和,实现对信号到达时间的最小二乘估计,最后评估了检测信噪比和采样率对估计精度的影响。与传统方法相比,所提方法能够将TOA估计误差的标准差降低50%~97%。该方法可推广应用于其他类型定时曲线。
