A GPS baseline solution model is presented,based on the Empirical Mode Decomposition(EMD),which has the advan- tage of eliminating the error effects outside the model.The EMD technique is a new signal processing metho...A GPS baseline solution model is presented,based on the Empirical Mode Decomposition(EMD),which has the advan- tage of eliminating the error effects outside the model.The EMD technique is a new signal processing method for non-linear time series,which decomposes a time series into a finite and often small number of Intrinsic Mode Functions(IMFs).The decomposition procedure is adaptive and data-driven which is suitable for non-linear data series analysis.A multi-scale decomposition and recon- struction architecture is defined on the basis of the EMD theory and the error mitigation model is demonstrated as well.A standard of the scale selection for the elimination of errors,outside the model,was given in terms of the mean of the accumulated standard- ized modes.Thereafter,the scheme of the GPS baseline solution based on the EMD is suggested.The float solution residuals of the Double-Difference(DD)observation equation are used to extract the errors outside the model applied to modify the GPS DD measurements.Then the float solution was given again and the fixed solution was obtained by a Lambda algorithm.Three schemes are designed to test the proposed model and the experimental results show that the proposed model dramatically improves the reli- ability of ambiguity resolution after the elimination of errors outside the model.展开更多
Based on the finite element （FE） program ANSYS, a three-dimensional model for the Runyang Suspension Bridge （RSB） is established. The structural natural frequency, vibration mode, stress and displacement response ...Based on the finite element （FE） program ANSYS, a three-dimensional model for the Runyang Suspension Bridge （RSB） is established. The structural natural frequency, vibration mode, stress and displacement response under various load cases are given. A new method of FE model updating is presented based on the physical meaning of sensitivity and the penalty function concept. In this method, the structural model is updated by modifying the parameters of design, and validated by structural natural vibration characteristics, stress response as well as displacement response. The design parameters used for updating are bounded according to measured static response and engineering judgment. The FE model of RSB is updated and validated by the measurements coming from the structural health monitoring system （SHMS）, and the FE baseline model reflecting the current state of RSB is achieved. Both the dynamic and static results show that the method is effective in updating the FE model of long span suspension bridges. The results obtained provide an important research basis for damage alarming and health monitoring of the RSB.展开更多
The Earth’s Free Core Nutation(FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance effects.High-precision superconducting gravimeter(SG) and very long baseline interfe...The Earth’s Free Core Nutation(FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance effects.High-precision superconducting gravimeter(SG) and very long baseline interferometry(VLBI) provide good observation techniques for detecting the FCN parameters.However,some choices in data processing and solution procedures increase the uncertainty of the FCN parameters.In this study,we analyzed the differences and the effectiveness of weight function and ocean tide corrections in the FCN parameter detection using synthetic data,SG data from thirty-one stations,and the 10 celestial pole offset(CPO) series.The results show that significant discrepancies are caused by different computing options for a single SG station.The stacking method,which results in a variation of0.24-5 sidereal days(SDs) in the FCN period(T) and 10^(3)-10^(4) in the quality factor(Q) due to the selection of the weighting function and the ocean tide model(OTM),can effectively suppress this influence.The statistical analysis results of synthetic data shows that although different weight choices,while adjusting the proportion of diurnal tidal waves involved,do not significantly improve the accuracy of fitted FCN parameters from gravity observations.The study evaluated a series of OTMs using the loading correction efficiency.The fitting of FCN parameters can be improved by selecting the mean of appropriate OTMs based on the evaluation results.Through the estimation of the FCN parameters based on the forced nutation,it was found that the weight function P_(1) is more suitable than others,and different CPO series(after 2009) resulted in a difference of 0.4 SDs in the T and of 103 in the Q.We estimated the FCN parameters for SG(T=430.4±1.5 SDs and Q=1.52×10^(4)±2.5×10^(3)) and for VLBI(T=429.8±0.7 SDs,Q=1.88×10^(4)±2.1×10^(3)).展开更多
基金Projects 40774010 supported by the National Natural Science Foundation of China20040290503 by the Research Fund for the Doctoral Program of Higher Education2006A029 by the Youth Scientific Research Foundation of China University of Mining and Technology
文摘A GPS baseline solution model is presented,based on the Empirical Mode Decomposition(EMD),which has the advan- tage of eliminating the error effects outside the model.The EMD technique is a new signal processing method for non-linear time series,which decomposes a time series into a finite and often small number of Intrinsic Mode Functions(IMFs).The decomposition procedure is adaptive and data-driven which is suitable for non-linear data series analysis.A multi-scale decomposition and recon- struction architecture is defined on the basis of the EMD theory and the error mitigation model is demonstrated as well.A standard of the scale selection for the elimination of errors,outside the model,was given in terms of the mean of the accumulated standard- ized modes.Thereafter,the scheme of the GPS baseline solution based on the EMD is suggested.The float solution residuals of the Double-Difference(DD)observation equation are used to extract the errors outside the model applied to modify the GPS DD measurements.Then the float solution was given again and the fixed solution was obtained by a Lambda algorithm.Three schemes are designed to test the proposed model and the experimental results show that the proposed model dramatically improves the reli- ability of ambiguity resolution after the elimination of errors outside the model.
文摘通过健康信息传播和教育说服公众形成健康行为意愿是一个现实课题。本文以精细加工可能性模型(elabo‐ration likelihood model,ELM)为理论基础,将说服路径分为中心路径和外围路径,同时引入短期的时间纵向数据追踪。本文实施了10天左右持续使用健康信息的日记报告实验,基于30名大学生提交的377条健康信息日记数据,建立个体层面与信息线索、时间层面的多层线性回归模型(hierarchical linear modeling,HLM),探究健康信息对个体健康行为意愿的说服机制。研究结果表明,健康行为意愿的说服过程主要是信息质量和来源可信度的混合式说服路径;在7天周期内,健康信息说服效果逐渐增强,其中信息质量的说服效果更为稳定,来源可信度的说服效果则随着时间推移逐渐被抵消;健康信息说服路径随个体特征和接触时机而变;健康意识调节来源可信度和信息热度对说服效果的影响,且具有时间效应;卷入度调节信息质量和来源可信度对信息说服效果的影响,但不存在时间效应。本文的研究结果有助于深入理解健康信息对健康行为意愿改变的说服机制,为建立“以人为本”的个性化健康信息传播和健康教育方案提供了参考。
文摘Based on the finite element （FE） program ANSYS, a three-dimensional model for the Runyang Suspension Bridge （RSB） is established. The structural natural frequency, vibration mode, stress and displacement response under various load cases are given. A new method of FE model updating is presented based on the physical meaning of sensitivity and the penalty function concept. In this method, the structural model is updated by modifying the parameters of design, and validated by structural natural vibration characteristics, stress response as well as displacement response. The design parameters used for updating are bounded according to measured static response and engineering judgment. The FE model of RSB is updated and validated by the measurements coming from the structural health monitoring system （SHMS）, and the FE baseline model reflecting the current state of RSB is achieved. Both the dynamic and static results show that the method is effective in updating the FE model of long span suspension bridges. The results obtained provide an important research basis for damage alarming and health monitoring of the RSB.
基金supported by the Open Fund of Hubei Luojia Laboratory (No. 220100033)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB41000000)+1 种基金National Natural Science Foundation of China (Grant Nos. 42174108, 41874094, 42192535 and 42242015)the Young Top-notch Talent Cultivation Program of Hubei Province。
文摘The Earth’s Free Core Nutation(FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance effects.High-precision superconducting gravimeter(SG) and very long baseline interferometry(VLBI) provide good observation techniques for detecting the FCN parameters.However,some choices in data processing and solution procedures increase the uncertainty of the FCN parameters.In this study,we analyzed the differences and the effectiveness of weight function and ocean tide corrections in the FCN parameter detection using synthetic data,SG data from thirty-one stations,and the 10 celestial pole offset(CPO) series.The results show that significant discrepancies are caused by different computing options for a single SG station.The stacking method,which results in a variation of0.24-5 sidereal days(SDs) in the FCN period(T) and 10^(3)-10^(4) in the quality factor(Q) due to the selection of the weighting function and the ocean tide model(OTM),can effectively suppress this influence.The statistical analysis results of synthetic data shows that although different weight choices,while adjusting the proportion of diurnal tidal waves involved,do not significantly improve the accuracy of fitted FCN parameters from gravity observations.The study evaluated a series of OTMs using the loading correction efficiency.The fitting of FCN parameters can be improved by selecting the mean of appropriate OTMs based on the evaluation results.Through the estimation of the FCN parameters based on the forced nutation,it was found that the weight function P_(1) is more suitable than others,and different CPO series(after 2009) resulted in a difference of 0.4 SDs in the T and of 103 in the Q.We estimated the FCN parameters for SG(T=430.4±1.5 SDs and Q=1.52×10^(4)±2.5×10^(3)) and for VLBI(T=429.8±0.7 SDs,Q=1.88×10^(4)±2.1×10^(3)).
