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An inverse algorithm for reconstructing the acoustic parameters of layered medium 认领 引用 被引量：1
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作者 LIN Junxuao 《Chinese Journal of Acoustics》 EI 1994年第4期311-314,共4页
The inverse problem in geophysics is to infer the vertical structure from the observed data. The crucial assumption in deriving inversion algorithms obtained for different elementary layer structures. Much of the prev... The inverse problem in geophysics is to infer the vertical structure from the observed data. The crucial assumption in deriving inversion algorithms obtained for different elementary layer structures. Much of the previous work on this problem for the case of plane wave at normal incidence has consisted of deriving a Schrodinger equation from the basic acoustic and stress-strain equations, and then reconstructing the potential appearing in this equation by using the Gelfand-Levitan procedure. We shall be concerned with structures in which the unknown coefficient has jump discontinuities. Here the unknown potential in the corresponding Gelfand-Levitan framework is highly singular, so much so that the theory breaks down. In this paper it is presented an inversion algorithm based on the Riccati equation,which avoids to solve the problem of singularity. The model experiment was conducted in a sewage pool of a factory. The final result of inversion agrecd well with the direct experimental observation. 展开更多
关键词 Inverse algorithm Layered medium
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Verification of the stability criterion of inverse algorithms for layered sea bottom 认领 引用 被引量：1
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作者 LIN Junxuan 《Chinese Journal of Acoustics》 1993年第1期83-88,共6页
In this paper, two inverse algorithms were used to infer the impedance profile of the layered bottom in a cooling-water pool. The error by two algorithms increased dramatically and leading to overflow in computation. ... In this paper, two inverse algorithms were used to infer the impedance profile of the layered bottom in a cooling-water pool. The error by two algorithms increased dramatically and leading to overflow in computation. Both inverse results were quite close to the measured data if the recorded data had been corrected by a stability criterion. 展开更多
关键词 wateracoustic Inverse algorithms,.
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Inverse Reinforcement Learning Optimal Control for Takagi-Sugeno Fuzzy Systems 认领 引用 被引量：1
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作者 Wenting SONG Shaocheng TONG 《Artificial Intelligence Science and Engineering》 2025年第2期134-146,共13页
Inverse reinforcement learning optimal control is under the framework of learner-expert.The learner system can imitate the expert system's demonstrated behaviors and does not require the predefined cost function,s... Inverse reinforcement learning optimal control is under the framework of learner-expert.The learner system can imitate the expert system's demonstrated behaviors and does not require the predefined cost function,so it can handle optimal control problems effectively.This paper proposes an inverse reinforcement learning optimal control method for Takagi-Sugeno(T-S)fuzzy systems.Based on learner systems,an expert system is constructed,where the learner system only knows the expert system's optimal control policy.To reconstruct the unknown cost function,we firstly develop a model-based inverse reinforcement learning algorithm for the case that systems dynamics are known.The developed model-based learning algorithm is consists of two learning stages:an inner reinforcement learning loop and an outer inverse optimal control loop.The inner loop desires to obtain optimal control policy via learner's cost function and the outer loop aims to update learner's state-penalty matrices via only using expert's optimal control policy.Then,to eliminate the requirement that the system dynamics must be known,a data-driven integral learning algorithm is presented.It is proved that the presented two algorithms are convergent and the developed inverse reinforcement learning optimal control scheme can ensure the controlled fuzzy learner systems to be asymptotically stable.Finally,we apply the proposed fuzzy optimal control to the truck-trailer system,and the computer simulation results verify the effectiveness of the presented approach. 展开更多
关键词 Takagi-Sugeno fuzzy systems learnerexpert framework inverse reinforcement learning algorithm optimal control
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Inverse method for the determination of elastic properties of coating layers by the surface ultrasonic waves 认领 引用
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作者 常军 杨震 许金泉 《Journal of Zhejiang University-SCIENCE A》 CAS 2005年第9期945-949,共5页
As the coated materials are widely applied in engineering, estimation of the elastic properties of coating layers is of great practical importance. This paper presents an inversion algorithm for determining the elasti... As the coated materials are widely applied in engineering, estimation of the elastic properties of coating layers is of great practical importance. This paper presents an inversion algorithm for determining the elastic properties of coating layers from the given velocity dispersion of surface ultrasonic waves. Based on the dispersive equation of surface waves in layered half space, an objective function dependent on coating material parameters is introduced. The density and wave velocities, which make the object function minimum, are taken as the inversion results. Inverse analyses of two parameters (longitudinal and transverse velocities) and three parameters (the density, longitudinal and transverse velocities) of the coating layer were made. 展开更多
关键词 Coating layers Surface waves Dispersive equation Inverse algorithm
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Analysis of Non-uniform Mechanical Behavior for a Continuous Casting Mold Based on Heat Flux from Inverse Problem 认领 引用 被引量：1
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作者 Feng-ming DU Xu-dong WANG +2 位作者 Yu LIU Tian-yi LI Man YAO 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2016年第2期83-91,共9页
The distortion of mold plates plays an important role in the formation of surface cracks on continuously cast steel products. To investigate the non-uniform distortion of a mold, a full-scale stress model of the mold ... The distortion of mold plates plays an important role in the formation of surface cracks on continuously cast steel products. To investigate the non-uniform distortion of a mold, a full-scale stress model of the mold was de veloped. An inverse algorithm was applied to calculate the heat flux using the temperatures measured by the thermo- couples buried inside the mold plates. Based on this, a full-scale, finite-element stress model, including four copper plates, a nickel layer and water slots in different depths, was built to determine the complex mechanical behavior of the continuous casting mold used to produce steel slabs. The heat flux calculated by the inverse algorithm was applied to the stress model to analyze the non-uniform mechanical behavior. The results showed that the stress and distortion distributions of the four copper plates were not symmetrical, which reflected the non-uniform distortion behaviors of copper plates, water slots, nickel layer and the corner region of the mold. The gap between the mold and the slab was increased because of the corner distortion, which was very important for the heat transfer of initial solidifying shell, and it may be a major reason for the slow cooling of the slab corner. 展开更多
关键词 finite-element stress model inverse algorithm nickel layer water slots continuous casting mold
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An improved multi-objective optimization algorithm for solving flexible job shop scheduling problem with variable batches 认领 引用 被引量：5
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作者 WU Xiuli PENG Junjian +2 位作者 XIE Zirun ZHAO Ning WU Shaomin 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2021年第2期272-285,共14页
In order to solve the flexible job shop scheduling problem with variable batches,we propose an improved multiobjective optimization algorithm,which combines the idea of inverse scheduling.First,a flexible job shop pro... In order to solve the flexible job shop scheduling problem with variable batches,we propose an improved multiobjective optimization algorithm,which combines the idea of inverse scheduling.First,a flexible job shop problem with the variable batches scheduling model is formulated.Second,we propose a batch optimization algorithm with inverse scheduling in which the batch size is adjusted by the dynamic feedback batch adjusting method.Moreover,in order to increase the diversity of the population,two methods are developed.One is the threshold to control the neighborhood updating,and the other is the dynamic clustering algorithm to update the population.Finally,a group of experiments are carried out.The results show that the improved multi-objective optimization algorithm can ensure the diversity of Pareto solutions effectively,and has effective performance in solving the flexible job shop scheduling problem with variable batches. 展开更多
关键词 flexible job shop variable batch inverse scheduling multi-objective evolutionary algorithm based on decomposition a batch optimization algorithm with inverse scheduling
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Inverse kinematics of a heavy duty manipulator with 6-DOF based on dual quaternion 认领 引用 被引量：10
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作者 王恒升 占德友 +1 位作者 黄平伦 陈伟锋 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第7期2568-2577,共10页
An iterative method is introduced successfully to solve the inverse kinematics of a 6-DOF manipulator of a tunnel drilling rig based on dual quaternion, which is difficult to get the solution by Denavit-Hartenberg(D-H... An iterative method is introduced successfully to solve the inverse kinematics of a 6-DOF manipulator of a tunnel drilling rig based on dual quaternion, which is difficult to get the solution by Denavit-Hartenberg(D-H) based methods. By the intuitive expression of dual quaternion to the orientation of rigid body, the coordinate frames assigned to each joint are established all in the same orientation, which does not need to use the D-H procedure. The compact and simple form of kinematic equations, consisting of position equations and orientation equations, is also the consequence of dual quaternion calculations. The iterative process is basically of two steps which are related to solving the position equations and orientation equations correspondingly. First, assume an initial value of the iterative variable; then, the position equations can be solved because of the reduced number of unknown variables in the position equations and the orientation equations can be solved by applying the solution from the position equations, which obtains an updated value for the iterative variable; finally, repeat the procedure by using the updated iterative variable to the position equations till the prescribed accuracy is obtained. The method proposed has a clear geometric meaning, and the algorithm is simple and direct. Simulation for 100 poses of the end frame shows that the average running time of inverse kinematics calculation for each demanded pose of end-effector is 7.2 ms on an ordinary laptop, which is good enough for practical use. The iteration counts 2-4 cycles generally, which is a quick convergence. The method proposed here has been successfully used in the project of automating a hydraulic rig. 展开更多
关键词 heavy-duty manipulator dual quaternion robotic kinematics inverse kinematics（IK） iterative algorithm tunnel drilling rig
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Random forest algorithm and regional applications of spectral inversion model for estimating canopy nitrogen concentration in rice 认领 引用 被引量：26
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作者 LI Xuqing LIU Xiangnan LIU Meiling WU Ling 《遥感学报》 CSCD 北大核心 2014年第4期923-945,共23页
Canopy Nitrogen Concentration （CNC） is a key indicator of crop yields. It is feasible to establish a real- time regional model to estimate CNC by upscaling the field-scale spectral model. This study focuses on monit... Canopy Nitrogen Concentration （CNC） is a key indicator of crop yields. It is feasible to establish a real- time regional model to estimate CNC by upscaling the field-scale spectral model. This study focuses on monitoring the CNC in rice on a large scale in real-time. The Random Forest （RF） algorithm is used to establish the CNC spectral inversion model, and some vegetation indexes that are sensitive to nitrogen were selected as input parameters for the RF. CNC was selected as an output parameter. The hyperspectral and biochemical data were collected in a paddy in Changchun City, Jilin Province, China, and the data in Suzhou was used to test the model＇s universality and effectiveness. Two regional-scale models were developed by applying scale transformation based on the input and output variables respectively. The results show that the RFCNC model （CNC spectral inversion model based on the RF algorithm） performed accurately and significantly improved upon existing methods. R2, used to validate method accuracy in Changchun and Suzhou, was 0.82 and 0.73 respectively. The regional application accuracy increased （R2= 0. 81） through the two upscaling methods using hyperspectral remote sensing satellite images. This study suggests that this method is promising for estimating regional CNC in rice by upscaling a field-scale spectral model if the strategy is appropriately selected. 展开更多
关键词 random forest algorithm, nitrogen inversion model, upscaling, regional application
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Research on grid based fire warning algorithm with YOLOv5s for palace buildings 认领 引用 被引量：1
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作者 Zhiming Wang Jiangnan Peng +2 位作者 Xinzhi Liu Changan Di Bo Wang 《Emergency Management Science and Technology》 2024年第1期213-221,共9页
In response to the early warning requirements of fire security technology in the Imperial Palace&large Ming and Qing ancient architectural complexes in China,a grid based fire warning algorithm is proposed by comb... In response to the early warning requirements of fire security technology in the Imperial Palace&large Ming and Qing ancient architectural complexes in China,a grid based fire warning algorithm is proposed by combining neural network YOLOv5s smoke detection technology.In this algorithm,the inverse proportional gridding algorithm based on building density is used to optimize the grid of buildings,and compared with the results of the equidistant grid algorithm,the risk distribution division is more detailed and reasonable.The smoke detection part uses YOLOv5s based smoke detection technology to detect the distribution of fire smoke in various areas,and the positioning of this area in the overall grid realized by the remote transmission module.With detection experiments on relevant datasets,the results show that its accuracy and mAP both reach 0.99.By utilizing the collaborative effect of inverse proportional gridding algorithm and smoke detection technology,a grid based visualization of smoke warning is achieved. 展开更多
关键词 combining neural network yolov s smoke detection technologyin risk distribution grid based fire warning algorithm early warning fire security technology equidistant grid algorithmthe optimize grid inverse proportional gridding algorithm
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DESIGN AND IMPLEMENTATION OF DUAL-FIELD MODULAR INVERSION ALGORITHM 认领 引用 被引量：1
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作者 Yang Xiaohui Yang Tongjie Dai Zibin Zhang Yongfu 《Journal of Electronics(China)》 2010年第4期531-537,共7页
Modular inverse arithmetic plays an important role in elliptic curve cryptography. Based on the analysis of Montgomery modular inversion algorithm, this paper presents a new dual-field modular inversion algorithm, and... Modular inverse arithmetic plays an important role in elliptic curve cryptography. Based on the analysis of Montgomery modular inversion algorithm, this paper presents a new dual-field modular inversion algorithm, and a novel scalable and unified architecture for Montgomery inverse hardware in finite fields GF(p) and GF(2n) is proposed. Furthermore, this architecture based on the new modular inversion algorithm has been verified by modeling it in Verilog-HDL, and accomplished it under 0.18 μm CMOS technology. The result indicates that our work has better performance and flexibility than other works. 展开更多
关键词 Modular inversion algorithm Dual field Unified architecture
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True-temperature inversion algorithm for a multi-wavelength pyrometer based on fractional-order particle-swarm optimization 认领 引用
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作者 Mei Liang Zhuo Sun +3 位作者 Jiasong Liu Yongsheng Wang Lei Liang Long Zhang 《Nanotechnology and Precision Engineering》 EI CAS CSCD 2024年第1期55-62,共8页
Herein,a method of true-temperature inversion for a multi-wavelength pyrometer based on fractional-order particle-swarm optimization is proposed for difficult inversion problems with unknown emissivity.Fractional-order... Herein,a method of true-temperature inversion for a multi-wavelength pyrometer based on fractional-order particle-swarm optimization is proposed for difficult inversion problems with unknown emissivity.Fractional-order calculus has the inherent advantage of easily jumping out of local extreme values;here,it is introduced into the particle-swarm algorithm to invert the true temperature.An improved adaptive-adjustment mechanism is applied to automatically adjust the current velocity order of the particles and update their velocity and position values,increasing the accuracy of the true temperature values.The results of simulations using the proposed algorithm were compared with three algorithms using typical emissivity models:the internal penalty function algorithm,the optimization function(fmincon)algorithm,and the conventional particle-swarm optimization algorithm.The results show that the proposed algorithm has good accuracy for true-temperature inversion.Actual experimental results from a rocket-motor plume were used to demonstrate that the true-temperature inversion results of this algorithm are in good agreement with the theoretical true-temperature values. 展开更多
关键词 Fractional-order particle swarm True-temperature inversion algorithm Multi-wavelength pyrometer
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Modified simulated annealing evolutionary algorithm for fully distributed fiber Bragg grating temperature sensing 认领 引用
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作者 陈娜 李承林 +4 位作者 陈振宜 庞拂飞 曾祥龙 孙晓岚 王廷云 《Journal of Shanghai University(English Edition)》 2011年第1期58-62,共5页
In this paper, we present a simple and fast spectra inversion method to reconstruct the temperature distribution along single fiber Bragg grating （FBC） temperature sensor. This is a fully distributed sensing method ... In this paper, we present a simple and fast spectra inversion method to reconstruct the temperature distribution along single fiber Bragg grating （FBC） temperature sensor. This is a fully distributed sensing method based on the simulated annealing evolutionary （SAE） algorithm. Several modifications are made to improve the algorithm efficiency, including choosing the most superior chromosome, setting up the boundary of every gene according to the density of resonance peaks of the reflection spectrum, and dynamically modifying the boundary with the algorithm running. Numerical simulation results show that both the convergence rate and the fluctuation are significantly improved. A high spat-ial temperature resolution of 0.25 mm has been achieved at the time cost of 86 s. 展开更多
关键词 fiber Bragg grating （FBG） spectrum inversion algorithm fully distributed temperature sensing
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Adaptive Antenna Utilizing Power Inversion and Linearly Constrained Minimum Variance Algorithms 认领 引用 被引量：17
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作者 E.A.MOHAMED 谈展中 《Chinese Journal of Aeronautics》 EI CAS 2005年第2期153-160,共8页
This paper presents a new algorithm based on the power inversion （PI） and the linearly constrained minimum variance （LCMV）. This algorithm is capable of adjusting the weights of the antenna array in real time to r... This paper presents a new algorithm based on the power inversion （PI） and the linearly constrained minimum variance （LCMV）. This algorithm is capable of adjusting the weights of the antenna array in real time to respond to and improve the global positioning system （GPS） received signals coming from the desired directions and at the same time to highly suppress the jammers coming from the other directions. The simulation is performed for fixed and moving jammers. It indicates that this structure can give deeper nulls, more than 115 dB depths for fixed jammers and more than 94 dB depths for moving jammers. 展开更多
关键词 adaptive antenna power inversion algorithm LCMV GPS anti-jamming
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Efficient Generalized Inverse for Solving Simultaneous Linear Equations 认领 引用
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作者 S. Kadiam Bose D. T. Nguyen 《Journal of Applied Mathematics and Physics》 2016年第1期16-20,共5页
Solving large scale system of Simultaneous Linear Equations (SLE) has been (and continue to be) a major challenging problem for many real-world engineering and science applications. Solving SLE with singular coefficie... Solving large scale system of Simultaneous Linear Equations (SLE) has been (and continue to be) a major challenging problem for many real-world engineering and science applications. Solving SLE with singular coefficient matrices arises from various engineering and sciences applications [1]-[6]. In this paper, efficient numerical procedures for finding the generalized (or pseudo) inverse of a general (squareectangle, symmetrical/unsymmetrical, non-singular/singular) matrix and solving systems of Simultaneous Linear Equations (SLE) are formulated and explained. The developed procedures and its associated computer software (under MATLAB [7] computer environment) have been based on “special Cholesky factorization schemes” (for a singular matrix). Test matrices from different fields of applications have been chosen, tested and compared with other existing algorithms. The results of the numerical tests have indicated that the developed procedures are far more efficient than the existing algorithms. 展开更多
关键词 Generalized Inverse Algorithms Simultaneous Linear Systems Matrix Inverse Singular Matrix Pseudo Inverse Cholesky Factorization
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A Time-Frequency Associated MUSIC Algorithm Research on Human Target Detection by Through-Wall Radar 认领 引用 被引量：3
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作者 Xianyu Dong Wu Ren +2 位作者 Zhenghui Xue Xuetian Wang Weiming Li 《Journal of Beijing Institute of Technology》 EI CAS 2022年第1期123-130,共8页
In this paper,a time-frequency associated multiple signal classification(MUSIC)al-gorithm which is suitable for through-wall detection is proposed.The technology of detecting hu-man targets by through-wall radar can b... In this paper,a time-frequency associated multiple signal classification(MUSIC)al-gorithm which is suitable for through-wall detection is proposed.The technology of detecting hu-man targets by through-wall radar can be used to monitor the status and the location information of human targets behind the wall.However,the detection is out of order when classical MUSIC al-gorithm is applied to estimate the direction of arrival.In order to solve the problem,a time-fre-quency associated MUSIC algorithm suitable for through-wall detection and based on S-band stepped frequency continuous wave(SFCW)radar is researched.By associating inverse fast Fouri-er transform(IFFT)algorithm with MUSIC algorithm,the power enhancement of the target sig-nal is completed according to the distance calculation results in the time domain.Then convert the signal to the frequency domain for direction of arrival(DOA)estimation.The simulations of two-dimensional human target detection in free space and the processing of measured data are com-pleted.By comparing the processing results of the two algorithms on the measured data,accuracy of DOA estimation of proposed algorithm is more than 75%,which is 50%higher than classical MUSIC algorithm.It is verified that the distance and angle of human target can be effectively de-tected via proposed algorithm. 展开更多
关键词 through-wall radar multiple signal classification(MUSIC)algorithm inverse fast Four-ier transform(IFFT)algorithm target detection
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Crustal velocity structure of central Gansu Province from regional seismic waveform inversion using firework algorithm 认领 引用 被引量：3
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作者 Yanyang Chen Yanbin Wang Yuansheng Zhang 《Earthquake Science》 CSCD 2017年第2期81-89,共9页
The firework algorithm（FWA） is a novel swarm intelligence-based method recently proposed for the optimization of multi-parameter, nonlinear functions. Numerical waveform inversion experiments using a synthetic model... The firework algorithm（FWA） is a novel swarm intelligence-based method recently proposed for the optimization of multi-parameter, nonlinear functions. Numerical waveform inversion experiments using a synthetic model show that the FWA performs well in both solution quality and efficiency. We apply the FWA in this study to crustal velocity structure inversion using regional seismic waveform data of central Gansu on the northeastern margin of the Qinghai-Tibet plateau. Seismograms recorded from the moment magnitude（MW） 5.4 Minxian earthquake enable obtaining an average crustal velocity model for this region. We initially carried out a series of FWA robustness tests in regional waveform inversion at the same earthquake and station positions across the study region,inverting two velocity structure models, with and without a low-velocity crustal layer; the accuracy of our average inversion results and their standard deviations reveal the advantages of the FWA for the inversion of regional seismic waveforms. We applied the FWA across our study area using three component waveform data recorded by nine broadband permanent seismic stations with epicentral distances ranging between 146 and 437 km. These inversion results show that the average thickness of the crust in this region is 46.75 km, while thicknesses of the sedimentary layer, and the upper, middle, and lower crust are 3.15,15.69, 13.08, and 14.83 km, respectively. Results also show that the P-wave velocities of these layers and the upper mantle are 4.47, 6.07, 6.12, 6.87, and 8.18 km/s,respectively. 展开更多
关键词 Seismic waveform inversion Crustal velocity structure Central Gansu Province Firework algorithm
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Delamination Identification for FRP Composites with Emphasis on Frequency-Based Vibration Monitoring-A Review 认领 引用
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作者 Mengyue He Zhifang Zhang Karthik Ram Ramakrishnan 《Structural Durability & Health Monitoring》 EI 2018年第4期213-256,共44页
Fibre reinforced polymer (FRP) composite laminates are now commonly usedin many structural applications, especially in the aerospace industry, where margins ofsafety are kept low in order to minimise weight. Timely de... Fibre reinforced polymer (FRP) composite laminates are now commonly usedin many structural applications, especially in the aerospace industry, where margins ofsafety are kept low in order to minimise weight. Timely detection and assessment ofdamage (in particular delaminations) in composite laminates are therefore critical, as theycan cause loss of structural integrity affecting the safe operation of the composite structures.The current trend is towards implementation of structural health monitoring (SHM)systems which can monitor the structures in situ without down time. In this paper, first, thecurrent available SHM techniques for delamination detection in FRP composites arebriefly reviewed, including acoustic emission, fibre optic sensors, Lamb wave-,impedance- and vibration-based methods. Among different vibration-based methods,frequency monitoring is the simplest to implement, requiring only single pointmeasurement, and is relatively accurate and reliable, thus it becomes the main focus ofpresent paper. A comprehensive review of frequency-based vibration monitoring isconducted in terms of the various aspects of delamination identification in FRPs throughfrequency shifts, including review of theoretical models for free vibration of delaminatedFRP beams, survey of finite element modelling of delaminated composite structures,summary of experimental modal analyses on FRP composites with delaminations, andinverse algorithms for frequency-based delamination assessment. This paper aims to helpthe readers to get an overview of the available SHM techniques for monitoring the integrityof FRP composites, with a special emphasis on delamination assessment throughfrequency-based vibration monitoring. 展开更多
关键词 Structural health monitoring delamination detection FRP compositestructures vibration-based method inverse algorithms
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一种用于位移场分析的应变模式频域数字图像相关方法 认领 引用 被引量：3
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作者 韩世豪 何玉明 +2 位作者 雷剑 谢宇阳 杨永波 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2023年第5期123-131,共9页
本文提出了一种在频域中考虑应变对位移影响的频域数字图像相关方法.研究并建立了一个在频域中评价参考图像子区与目标图像子区之间匹配的评价标准,并在此基础之上,提出了可用于位移和应变计算的频域迭代算法,其中,Hessian矩阵在迭代过... 本文提出了一种在频域中考虑应变对位移影响的频域数字图像相关方法.研究并建立了一个在频域中评价参考图像子区与目标图像子区之间匹配的评价标准,并在此基础之上,提出了可用于位移和应变计算的频域迭代算法,其中,Hessian矩阵在迭代过程中保持不变.在Hessian矩阵的形成过程中,参考图像子区中灰度的梯度可以通过快速傅里叶变换进行计算,具有很高的计算效率和精度.同时,一种离散傅里叶变换重采样技术被用于代替传统的插值方法对变形图像子区中亚像素位置的灰度进行重建和更新.为了验证所提方法的有效性和准确性,使用了国际DIC挑战委员会(IDCC)提供的系列图像(2D-Challenge 1.0,样本6)进行位移分析.分析的误差结果表明,在子区大小为41×41像素的条件下,对变形为50%的模拟实验进行了计算,位移分析结果的精度约为0.0032像素(最大绝对值误差),在精度上优于已发表的文献.最后,对硅橡胶试件进行了14.85%的单轴拉伸试验,通过相关系数分布检验了本文所提方法在实际应用中的有效性,并给出了分析的位移和应变分布. 展开更多
关键词 Digital image correlation Fourier transform Inverse compositional image alignment algorithm Strain measurement
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Nonlinear inversion of ultrasonic guided waves for in vivo evaluation of cortical bone properties 认领 引用 被引量：1
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作者 Xiaojun Song Tii Fan +6 位作者 Jundong Zeng Qin-Zhen Shi Qiong Huang Meilin Gu Petro Moilanen Yi-Fang Li Dean Ta 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第7期371-378,共8页
Ultrasonic guided waves(UGWs),which propagate throughout the entire thickness of cortical bone,are attractive for the early diagnosis of osteoporosis.However,this is challenging due to the impact of soft tissue and th... Ultrasonic guided waves(UGWs),which propagate throughout the entire thickness of cortical bone,are attractive for the early diagnosis of osteoporosis.However,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 velocity.Therefore,in this research,a UGW-based multi-parameter inversion algorithm is developed to predict strength-related factors.In simulation,a free plate(cortical bone)and a bilayer plate(soft tissue and cortical bone)are used to validate the proposed method.The inversed cortical thickness(CTh),longitudinal velocity(VL)and transverse velocity(VT)are in accordance with the true values.Then four bovine cortical bone plates were used in in vitro experiments.Compared with the reference values,the relative errors for cortical thickness were 3.96%,0.83%,2.87%,and 4.25%,respectively.In the in vivo measurements,UGWs are collected from the tibias of 10 volunteers.The theoretical dispersion curves depicted by the estimated parameters(VT,VL,CTh)match well with the extracted experimental ones.In comparison with dual-energy x-ray absorptiometry,our results show that the estimated transverse velocity and cortical thickness are highly sensitive to osteoporosis.Therefore,these two parameters(CTh and VT)of long bones have potential to be used for diagnosis of bone status in clinical applications. 展开更多
关键词 ultrasonic guided waves inversion algorithm transverse velocity bone evaluation
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Seismic fluid identification using a nonlinear elastic impedance inversion method based on a fast Markov chain Monte Carlo method 认领 引用 被引量：6
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作者 Guang-Zhi Zhang Xin-Peng Pan +2 位作者 Zhen-Zhen Li Chang-Lu Sun Xing-Yao Yin 《Petroleum Science》 SCIE CAS CSCD 2015年第3期406-416,共11页
Elastic impedance inversion with high efficiency and high stability has become one of the main directions of seismic pre-stack inversion. The nonlinear elastic impedance inversion method based on a fast Markov chain M... Elastic impedance inversion with high efficiency and high stability has become one of the main directions of seismic pre-stack inversion. The nonlinear elastic impedance inversion method based on a fast Markov chain Monte Carlo （MCMC） method is proposed in this paper, combining conventional MCMC method based on global optimization with a preconditioned conjugate gradient （PCG） algorithm based on local optimization, so this method does not depend strongly on the initial model. It converges to the global optimum quickly and efficiently on the condition that effi- ciency and stability of inversion are both taken into consid- eration at the same time. The test data verify the feasibility and robustness of the method, and based on this method, we extract the effective pore-fluid bulk modulus, which is applied to reservoir fluid identification and detection, and consequently, a better result has been achieved. 展开更多
关键词 Elastic impedance Nonlinear inversion FastMarkov chain Monte Carlo method - Preconditionedconjugate gradient algorithm ~ Effective pore-fluid bulkmodulus
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