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作者： Yu TIAN College of Oceanography Minjiang University State Key Laboratory of Geodesy and Geodynamics Institute of Geodesy and GeophysicsChinese Academy of Sciences

This paper proposed a folding calculation method based on preconditioned conjugate gradient inversion algorithm to cope with the non-uniqueness of the solution in gravity gradient tensor *** with the original algorithm,which takes the entire study area as the research object and uses all grid cells in the inversion calculation;the folding calculation method,uses random one of the prismatic unit at the four corner grids of the study area as the area for the first iterative *** calculated density anomaly value is used as the initial density anomaly value of the area for the next round of folding *** folding calculations are alternately performed in the manner of left-right or up-down folding with strong regularity until the inversion calculation of the entire study area is *** statistical analysis of the multiple sets of inversion results shows that the improved inversion algorithm simultaneously constrains the model error under the condition that the relative fit difference standard of the observed values is satisfied,and the model error value of the inversion result is smaller and concentrated around the *** results show that the improved algorithm can be effectively applied to the inversion of gravity gradient data,and the inversion results show more detailed and reliable distribution information of density *** method can be used to quickly obtain the detail information of the density anomalies in the mining area.

关键词： Folding calculation Gravity gradient inversion algorithm

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Nonlinear inversion of ultrasonic guided waves for in vivo evaluation of cortical bone properties

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Chinese Physics B 2022年第7期31卷 371-378页

作者：宋小军樊天地曾俊冬石勤振黄琼顾美琳 Petro Moilanen 李义方他得安 Center for Biomedical Engineering Fudan UniversityShanghai 200433China College of Electronics and Information engineering Shanghai University of Electric PowerShanghai 200090China Department of Physics University of HelsinkiHelsinkiFinland Academy for Engineering and Technology Fudan UniversityShanghai 200433China

Ultrasonic guided waves(UGWs),which propagate throughout the entire thickness of cortical bone,are attractive for the early diagnosis of ***,this is challenging due to the impact of soft tissue and the inherent difficulties related to multiparametric inversion of cortical bone quality factors,such as cortical thickness and bulk wave ***,in this research,a UGW-based multi-parameter inversion algorithm is developed to predict strength-related *** simulation,a free plate(cortical bone)and a bilayer plate(soft tissue and cortical bone)are used to validate the proposed *** inversed cortical thickness(CTh),longitudinal velocity(V_(L))and transverse velocity(V_(T))are in accordance with the true *** four bovine cortical bone plates were used in in vitro *** with the reference values,the relative errors for cortical thickness were 3.96%,0.83%,2.87%,and 4.25%,*** the in vivo measurements,UGWs are collected from the tibias of 10 *** theoretical dispersion curves depicted by the estimated parameters(V_(T),V_(L),CTh)match well with the extracted experimental *** comparison with dual-energy x-ray absorptiometry,our results show that the estimated transverse velocity and cortical thickness are highly sensitive to ***,these two parameters(CTh and V_(T))of long bones have potential to be used for diagnosis of bone status in clinical applications.

关键词： ultrasonic guided waves inversion algorithm transverse velocity bone evaluation

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Optimization of regularization parameter of inversion in particle sizing using light extinction method

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China Particuology 2007年第4期5卷 295-299页

作者： Mingxu Su Feng Xu Xiaoshu Cai Kuanfang Ren Jianqi Shen Institute of Particle and Two Phase Flow Measurement Technology University of Shanghai .for Science and Technology Shanghai 200093 China LESP UMR6614/CORIA CNRS-Universite France INSA de Rouen 76801 France

In particle sizing by light extinction method, the regularization parameter plays an important role in applying regularization to find the solution to ill-posed inverse problems. We combine the generalized cross-validation （GCV） and L-curve criteria with the Twomey-NNLS algorithm in parameter optimization. Numerical simulation and experimental validation show that the resistance of the newly developed algorithms to measurement errors can be improved leading to stable inversion results for unimodal particle size distribution.

关键词： Particle size analysis Light extinction inversion algorithm Regularization parameter

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Water quality monitoring and evaluation using remote sensing techniques in China:a systematic review

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Ecosystem Health and Sustainability 2019年第1期5卷 47-56,I0023页

作者： Xiaoyan Wang Wu Yang College of Environmental and Resource Sciences Zhejiang UniversityHangzhouChina

Introduction:The application of remote-sensing techniques for water quality assessment has become increasingly popular in ***,existing reviews are often limited to qualitative description and are quite ***:We conducted a quantitative systematic review to display current research status and identify the existing challenges and future *** review revealed that the application of remote-sensing techniques in water quality research has expanded dramatically in China,but the spatial distribution is quite ***,the ground object spectrometer is the most widely applied data *** color indicators such as chlorophyll a and suspended solid are the most widely investigated in ***,semiempirical method is the most commonly used inversion *** studies rarely considered the anthropogenic factors,which limited the model robustness and its application in humandominated aquatic *** and Conclusion:We concluded that,in the past several decades,China has made notable progresses in monitoring and evaluation of water quality using the remote-sensing techniques(especially in inland lakes).We proposed that further improvements would be needed in terms of temporal and spatial coverage,indicator list,the incorporation of human–nature interactions,inversion accuracy,and model generalization.

关键词： Chlorophyll a coupled human and natural systems inversion algorithm suspended solid water quality indicators water resource management

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A NEW algorithm OF RELAXATION METHOD FOR PARTICLE ANALYSIS FROM FORWARD SCATTERED LIGHT

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China Particuology 2006年第1期4卷 13-19页

作者： Jianqi Shen Mingxu Su Junfeng Li University of Shanghai for Science and Technology Shanghai 200093 P. R. China

A new algorithm of the relaxation method is developed for the inversion of forward scattered light to obtain the size distribution of spherical particles. Numerical tests are performed for a laser particle analyzer using the Mie theory and the diffraction approximation. The algorithm efficiency, in the presence of experimental noises, is studied. The results show that the technique is fast in convergence, stable against random noise and insensitive to the distribution of particles and the initial trial distribution.

关键词： particle size analysis forward scattering inversion algorithm relaxation method

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