Pulse laser range detector is to measure the distance by estimating the time delay between the emitting pulse and echo pulse.In this paper,a mathematical model for the target echo signal of laser fuze has been establi...Pulse laser range detector is to measure the distance by estimating the time delay between the emitting pulse and echo pulse.In this paper,a mathematical model for the target echo signal of laser fuze has been established;in accordance with this model,the formulas for echo time-delay estimation and for amplitude estimation based on least squares criterion have been deduced.It is argued and simulated that the resolution of echo time-delay estimation could be improved through multi-reference correlation approach.Experiments illustrate that the approach enables pulsed laser fuze to perform high-precision ranging under a low signal-to-noise ratio condition.展开更多
This study explored the application value of iterative decomposition of water and fatwith echo asymmetry and least-squares estimation(IDEAL-IQ)technology in the early diagnosis of ageing osteoporosis(OP).172 participa...This study explored the application value of iterative decomposition of water and fatwith echo asymmetry and least-squares estimation(IDEAL-IQ)technology in the early diagnosis of ageing osteoporosis(OP).172 participants were enrolled and underwentmagnetic resonance imaging(MRI)examinations on a 3.0T scanner.100 cases were included in the normal group(50 males and 50 females;mean age:45 years;age range:20e84 years).33 cases were included in the osteopenia group(17 males and 16 females;mean age:55 years;age range:43e83 years).39 caseswere includedintheOP group(19males and20females;meanage:58years;age range:48 e82 years).Conventional T1WI and T2WI were first obtained,followed by 3D-IDEAL-IQ-acqui-sition.Fat fraction(FF)and apparent transverse relaxation rate(R2*)resultswere automatically calculated from IDEAL-IQ-images on the console.Based on T1Wand T2W-images,300 ROIs for each participantweremanually delineated in L1-L5 vertebral bodies of five middle slices.In each age group of all normal subjects,each parameter was significantly correlated with gender.In male participants from the normal,osteopenia,and OP groups,statistical analysis revealed F values of 11319.292 and 180.130 for comparisons involving FF and R2*values,respectively(all p<0.0001).The sensitivity and specificity of FF values were 0.906 and 0.950,0.994 and 0.997,0.865 and 0.820,respectively.For R2*,they were 0.665 and 0.616,0.563 and 0.519,0.571 and 0.368,respectively.In female participants from the normal,osteopenia,and OP-groups,statis-tical analysis revealed F values of 12461.658 and 548.274 for comparisons involving FF and R2*values,respectively(all p<0.0001).The sensitivity and specificity of FF values were 0.985 and 0.991,0.996 and 0.996,0.581 and 0.678,respectively.For R2*,they were 0.698 and 0.730,0.603 and 0.665,0.622 and 0.525,respectively.Significant differences were indicated in the quanti-tative values among the three groups.FF value had good performance,while R2*value had poor performance indiscriminatingosteopenia andOP-groups.Overall,the IDEAL-IQ techniqueoffers specific reference indices that enable noninvasive and quantitative assessment of lumbar vertebrae bone metabolism,thereby providing diagnostic information for OP.展开更多
For a class of time-delay discrete-time linear systems with external disturbance and measurement noise, the interval estimation problems of state and measurement noise are investigated in this paper. First, the system...For a class of time-delay discrete-time linear systems with external disturbance and measurement noise, the interval estimation problems of state and measurement noise are investigated in this paper. First, the system state together with the time-delay term and measurement noise is augmented as a new state, and a singular system is then constructed. Subsequently, a kind of decoupling technique is employed to eliminate the effect of external disturbance, and an observer is designed to simultaneously estimate the system state and measurement noise. Based on the estimated state and measurement noise, the interval estimations of system state and measurement noise are obtained by reachability analysis technique. Finally, the effectiveness of the proposed method is verified by a four-tank liquid level system.展开更多
The passive acoustic localization with planar sensor array is introduced. Based on a method to eliminate the influence of effective sound velocity in passive detection, a new five-sensors solid array and its localizat...The passive acoustic localization with planar sensor array is introduced. Based on a method to eliminate the influence of effective sound velocity in passive detection, a new five-sensors solid array and its localization model are put forward. The factors that influence the precision of the localization are analyzed. Considering the errors from the factors synchronously, the simulation compares the solid array with the planar array. It can be proved that the five-sensor solid array is better than the four-sensor planar array in the estimation of bearing elements.展开更多
This paper presented an improved channel estimator for orthogonal frequency division muhiplexing （OFDM） systems using joint time delay detection and channel gain estimation. The algorithm well designs an adjustment ...This paper presented an improved channel estimator for orthogonal frequency division muhiplexing （OFDM） systems using joint time delay detection and channel gain estimation. The algorithm well designs an adjustment scheme using the time correlation of time delays to increase the accuracy of the time delay detection. The most attractive advantage is that the complicated matrix calculation is replaced by the search steps to estimate the channel parameters without significantly increasing the complexity of the system. The computer simulation demonstrates that the proposed algorithm can track the time delays adaptively and improve the channel estimation performance. Consequently, the better system performance will be achieved.展开更多
This article studies the feasibility of noninvasive temperature estimation by detecting echo-strain including thermal expansion in therapeutic ultrasound treatment. This technique evaluates distributions of echo-strai...This article studies the feasibility of noninvasive temperature estimation by detecting echo-strain including thermal expansion in therapeutic ultrasound treatment. This technique evaluates distributions of echo-strain and temperature inside the tissue by detecting echo signals pre- and post-heating, in combination with the temperature dependence of sound speed and thermal expansion. In the computer simulation and experimental study, echo signals pre- and post- heating are acquired and then the temperature elevation is evaluated by correlation analysis. Results demonstrate that this technique can effectively extend the measured temperature range up to 75℃ with an accuracy of±2 ℃.展开更多
This paper deals with the problem of H∞ fault estimation for linear time-delay systems in finite frequency domain.First a generalized coordinate change is applied to the original system such that in the new coordinat...This paper deals with the problem of H∞ fault estimation for linear time-delay systems in finite frequency domain.First a generalized coordinate change is applied to the original system such that in the new coordinates all the time-delay terms are injected by the system＇s input and output.Then an observer-based H∞ fault estimator with input and output injections is proposed for fault estimation with known frequency range.With the aid of Generalized Kalman-Yakubovich-Popov lemma,sufficient conditions on the existence of the H∞ fault estimator are derived and a solution to the observer gain matrices is obtained by solving a set of linear matrix inequalities.Finally,a numerical example is given to illustrate the effectiveness of the proposed method.展开更多
It is proposed firstly that the original phase and the time-delay are the main factors which affect the measuring resolution of the multitone complex envelope method. The effects of these factors are analysed and chec...It is proposed firstly that the original phase and the time-delay are the main factors which affect the measuring resolution of the multitone complex envelope method. The effects of these factors are analysed and checked by the computer simulation. Finally, three possible ways to eliminate these effects are given.展开更多
This paper addresses the problem of channel estimation for broadband MIMO-OFDM systems. An improved channel estimator with multipath time delay detection and channel gain estimation is proposed. In the algorithm, we u...This paper addresses the problem of channel estimation for broadband MIMO-OFDM systems. An improved channel estimator with multipath time delay detection and channel gain estimation is proposed. In the algorithm, we used the correlation of the channel taps and a well-designed adjustment scheme to increase the accuracy of the time delay detection. The most attractive advantage is that the complicated matrix calculation is replaced by search steps which can acquire the channel order and estimate the channel parameters without significantly increasing the complexity of the system. Computer simulation showed that the proposed algorithm can track the time delays adaptively and, consequently, improve the channel estimation performance.展开更多
Including information of the current road surface conditions can significantly improve the effectiveness of an AEB （automated emergency braking） system to avoid accidents or reduce the injury severity in rear-end cr...Including information of the current road surface conditions can significantly improve the effectiveness of an AEB （automated emergency braking） system to avoid accidents or reduce the injury severity in rear-end crashes. A method to estimate the friction potential based on on-board sensor information is shown in this work. This work expands the scope of existing investigations on whether the accuracy needed for the warning and intervention strategies of AEB can be reached with the proposed method. First, the bandwidth of surface conditions investigated is extended by including low friction surfaces comparable to ice. Second, situations of changing surface conditions and wheel-individual surface conditions were evaluated. Finally, estimation based on different sensor sets was conducted with regard to series application. The investigations are based on measurements performed on a proving ground. The main emphasis was placed on estimation during longitudinal driving conditions. The used sensors include advanced vehicle dynamics measurement equipment as well as standard on-board sensors of the vehicle.展开更多
White noise deconvolution or input white noise estimation problem has important appli-cation backgrounds in oil seismic exploration,communication and signal processing.By the modern time series analysis method,based o...White noise deconvolution or input white noise estimation problem has important appli-cation backgrounds in oil seismic exploration,communication and signal processing.By the modern time series analysis method,based on the Auto-Regressive Moving Average(ARMA) innovation model,under the linear minimum variance optimal fusion rules,three optimal weighted fusion white noise deconvolution estimators are presented for the multisensor systems with time-delayed measurements and colored measurement noises.They can handle the input white noise fused filtering,prediction and smoothing problems.The accuracy of the fusers is higher than that of each local white noise estimator.In order to compute the optimal weights,the formula of computing the local estimation error cross-covariances is given.A Monte Carlo simulation example for the system with 3 sensors and the Bernoulli-Gaussian input white noise shows their effectiveness and performances.展开更多
目的:以MRI测定的全肝脏质子密度脂肪分数(PDFF)为标准,探讨MRI可变容积加速肝脏采集(LAVA-Flex)技术和非对称回波最小二乘估算法迭代水脂分离(IDEAL-IQ)技术测定的代谢相关脂肪性肝病(MAFLD)患者的水相、脂相图肝脏脂肪分数(FF)与PDFF...目的:以MRI测定的全肝脏质子密度脂肪分数(PDFF)为标准,探讨MRI可变容积加速肝脏采集(LAVA-Flex)技术和非对称回波最小二乘估算法迭代水脂分离(IDEAL-IQ)技术测定的代谢相关脂肪性肝病(MAFLD)患者的水相、脂相图肝脏脂肪分数(FF)与PDFF的一致性。探讨LAVA-Flex技术行全肝脏脂肪定量快速检测的可行性。方法:收集97例MAFLD患者及23例健康志愿者。在GE 1.5 T MRI扫描仪上行IDEAL-IQ和LAVA-Flex序列扫描,前者得出PDFF、R2*、水相、脂相、同相位、反相位图,后者得出水相、脂相、同相位、反相位图。使用3D Slicer软件对PDFF、水相、脂相图进行全肝勾画,计算全肝各水相、脂相图的脂肪信号分数(FF_(IQ))和(FF_(Flex))。根据PDFF将120例分成4组:正常组23例,PDFF<5%;轻度组15例,5%≤PDFF<10%;中度组48例,10%≤PDFF<25%;重度组34例,PDFF≥25%。使用Pearson相关性分析评估4组FF_(IQ)、FF_(Flex)与PDFF的一致性,并绘制相关性热图及Bland-Altman图。结果:总体FF_(Flex)与PDFF呈极强相关(r=0.959);正常组FF_(IQ)与PDFF呈极强的相关(r=0.991,P<0.01);轻度组FF_(IQ)与PDFF呈较强相关(r=0.848,P<0.01);中度组FF_(IQ)与PDFF呈极强相关(r=0.997,P<0.01),FF_(Flex)与PDFF呈较强相关(r=0.756,P<0.01);重度组FF_(IQ)、FF_(Flex)均与PDFF呈显著相关(r=0.779,0.793;均P<0.01)。Bland-Altman图显示,FF_(Flex)与FF_(IQ)大部分数据点均落在一致性限内,且中心线接近0,两者与PDFF均具有很好的一致性。结论:IDEAL-IQ和LAVA-Flex技术测定的全肝FF与PDFF呈高度一致性,尤其是在中、重度脂肪肝患者中表现更佳,LAVA-Flex技术以其快速成像的优势为临床肝脏脂肪含量的测定提供了重要工具。展开更多
Sonar locates underwater targets by receiving reflected sound waves.However,the complex marine environment makes it difficult to set targets in appropriate locations and conditions.The sonar echo simulator has the fun...Sonar locates underwater targets by receiving reflected sound waves.However,the complex marine environment makes it difficult to set targets in appropriate locations and conditions.The sonar echo simulator has the function of simulating sonar detection target echo signals.As a cutting-edge technology,underwater backscatter has led to the emergence of array based acoustic reflection systems.The research on sonar echo simulators based on backscatter technology has promoted the solution of problems such as target echo modeling,sonar arrival direction estimation,and echo directional transmission.In response to the above problems,this paper designs an end-to-end sonar echo simulator system array phase estimation sonar echo simulation system(APE-SESS),which can independently complete highresolution real-time direction of arrival(DOA)estimation and generate directional simulation echo based on the array structure.Dual branch convolutional neural network(DB-CNN)is proposed in the system to estimate the direction of the signal array and directly obtain the phase weights containing azimuth information.Comparing DBCNN with conventional methods and classic underwater DOA network models based on classification problems,the results show that DB-CNN exhibits stability,small error,and high real-time performance under different signal-to-noise ratio(SNR).The proposed APE-SESS has end-to-end characteristics,real-time angle estimation,and azimuth simulation functions.展开更多
This paper presents an Ethernet based hybrid method for predicting random time-delay in the networked control system.First,db3 wavelet is used to decompose and reconstruct time-delay sequence,and the approximation com...This paper presents an Ethernet based hybrid method for predicting random time-delay in the networked control system.First,db3 wavelet is used to decompose and reconstruct time-delay sequence,and the approximation component and detail components of time-delay sequences are fgured out.Next,one step prediction of time-delay is obtained through echo state network(ESN)model and auto-regressive integrated moving average model(ARIMA)according to the diferent characteristics of approximate component and detail components.Then,the fnal predictive value of time-delay is obtained by summation.Meanwhile,the parameters of echo state network is optimized by genetic algorithm.The simulation results indicate that higher accuracy can be achieved through this prediction method.展开更多
基金Sponsored by the National Defense Science and Technology Laboratory Foundation (9140C3601130802)
文摘Pulse laser range detector is to measure the distance by estimating the time delay between the emitting pulse and echo pulse.In this paper,a mathematical model for the target echo signal of laser fuze has been established;in accordance with this model,the formulas for echo time-delay estimation and for amplitude estimation based on least squares criterion have been deduced.It is argued and simulated that the resolution of echo time-delay estimation could be improved through multi-reference correlation approach.Experiments illustrate that the approach enables pulsed laser fuze to perform high-precision ranging under a low signal-to-noise ratio condition.
基金supported by the Planned Project Grant(Grant No.3502Z20199064)from the Science and Technology Bureau of Xiamen(CN)the training project(Grant No.2020GGB067)of the youth and middle-aged talents of Fujian Provincial Health Commission(CN).
文摘This study explored the application value of iterative decomposition of water and fatwith echo asymmetry and least-squares estimation(IDEAL-IQ)technology in the early diagnosis of ageing osteoporosis(OP).172 participants were enrolled and underwentmagnetic resonance imaging(MRI)examinations on a 3.0T scanner.100 cases were included in the normal group(50 males and 50 females;mean age:45 years;age range:20e84 years).33 cases were included in the osteopenia group(17 males and 16 females;mean age:55 years;age range:43e83 years).39 caseswere includedintheOP group(19males and20females;meanage:58years;age range:48 e82 years).Conventional T1WI and T2WI were first obtained,followed by 3D-IDEAL-IQ-acqui-sition.Fat fraction(FF)and apparent transverse relaxation rate(R2*)resultswere automatically calculated from IDEAL-IQ-images on the console.Based on T1Wand T2W-images,300 ROIs for each participantweremanually delineated in L1-L5 vertebral bodies of five middle slices.In each age group of all normal subjects,each parameter was significantly correlated with gender.In male participants from the normal,osteopenia,and OP groups,statistical analysis revealed F values of 11319.292 and 180.130 for comparisons involving FF and R2*values,respectively(all p<0.0001).The sensitivity and specificity of FF values were 0.906 and 0.950,0.994 and 0.997,0.865 and 0.820,respectively.For R2*,they were 0.665 and 0.616,0.563 and 0.519,0.571 and 0.368,respectively.In female participants from the normal,osteopenia,and OP-groups,statis-tical analysis revealed F values of 12461.658 and 548.274 for comparisons involving FF and R2*values,respectively(all p<0.0001).The sensitivity and specificity of FF values were 0.985 and 0.991,0.996 and 0.996,0.581 and 0.678,respectively.For R2*,they were 0.698 and 0.730,0.603 and 0.665,0.622 and 0.525,respectively.Significant differences were indicated in the quanti-tative values among the three groups.FF value had good performance,while R2*value had poor performance indiscriminatingosteopenia andOP-groups.Overall,the IDEAL-IQ techniqueoffers specific reference indices that enable noninvasive and quantitative assessment of lumbar vertebrae bone metabolism,thereby providing diagnostic information for OP.
基金supported in part by the National Nature Science Foundation of China(No.61973105)the Natural Science Foundation of Henan Province(No.232300420147)the Fundamental Research Funds for the Universities of Henan Province(No.NSFRF180335).
文摘For a class of time-delay discrete-time linear systems with external disturbance and measurement noise, the interval estimation problems of state and measurement noise are investigated in this paper. First, the system state together with the time-delay term and measurement noise is augmented as a new state, and a singular system is then constructed. Subsequently, a kind of decoupling technique is employed to eliminate the effect of external disturbance, and an observer is designed to simultaneously estimate the system state and measurement noise. Based on the estimated state and measurement noise, the interval estimations of system state and measurement noise are obtained by reachability analysis technique. Finally, the effectiveness of the proposed method is verified by a four-tank liquid level system.
文摘The passive acoustic localization with planar sensor array is introduced. Based on a method to eliminate the influence of effective sound velocity in passive detection, a new five-sensors solid array and its localization model are put forward. The factors that influence the precision of the localization are analyzed. Considering the errors from the factors synchronously, the simulation compares the solid array with the planar array. It can be proved that the five-sensor solid array is better than the four-sensor planar array in the estimation of bearing elements.
基金National Natural Science Foundation of China(No. 60272079, No. 60332030)NationalHigh Technology Research and DevelopmentProgram of China ( 863 Program) ( No.2003AA123310)
文摘This paper presented an improved channel estimator for orthogonal frequency division muhiplexing （OFDM） systems using joint time delay detection and channel gain estimation. The algorithm well designs an adjustment scheme using the time correlation of time delays to increase the accuracy of the time delay detection. The most attractive advantage is that the complicated matrix calculation is replaced by the search steps to estimate the channel parameters without significantly increasing the complexity of the system. The computer simulation demonstrates that the proposed algorithm can track the time delays adaptively and improve the channel estimation performance. Consequently, the better system performance will be achieved.
基金Project supported by the National Natural Science Foundation of China （Grant No 10474044） and the Program for New Century Excellent Talents in University of China （CNCET）.
文摘This article studies the feasibility of noninvasive temperature estimation by detecting echo-strain including thermal expansion in therapeutic ultrasound treatment. This technique evaluates distributions of echo-strain and temperature inside the tissue by detecting echo signals pre- and post-heating, in combination with the temperature dependence of sound speed and thermal expansion. In the computer simulation and experimental study, echo signals pre- and post- heating are acquired and then the temperature elevation is evaluated by correlation analysis. Results demonstrate that this technique can effectively extend the measured temperature range up to 75℃ with an accuracy of±2 ℃.
基金supported in part by the National Natural Science Foundation of China (60774071)the National High Technology Research and Development Program of China (863 Program) (2008AA121302)+1 种基金the Major State Basic Research Development Program of China (973 Program) (2009CB724000)the State Scholarship Fund of China
文摘This paper deals with the problem of H∞ fault estimation for linear time-delay systems in finite frequency domain.First a generalized coordinate change is applied to the original system such that in the new coordinates all the time-delay terms are injected by the system＇s input and output.Then an observer-based H∞ fault estimator with input and output injections is proposed for fault estimation with known frequency range.With the aid of Generalized Kalman-Yakubovich-Popov lemma,sufficient conditions on the existence of the H∞ fault estimator are derived and a solution to the observer gain matrices is obtained by solving a set of linear matrix inequalities.Finally,a numerical example is given to illustrate the effectiveness of the proposed method.
文摘It is proposed firstly that the original phase and the time-delay are the main factors which affect the measuring resolution of the multitone complex envelope method. The effects of these factors are analysed and checked by the computer simulation. Finally, three possible ways to eliminate these effects are given.
文摘This paper addresses the problem of channel estimation for broadband MIMO-OFDM systems. An improved channel estimator with multipath time delay detection and channel gain estimation is proposed. In the algorithm, we used the correlation of the channel taps and a well-designed adjustment scheme to increase the accuracy of the time delay detection. The most attractive advantage is that the complicated matrix calculation is replaced by search steps which can acquire the channel order and estimate the channel parameters without significantly increasing the complexity of the system. Computer simulation showed that the proposed algorithm can track the time delays adaptively and, consequently, improve the channel estimation performance.
文摘Including information of the current road surface conditions can significantly improve the effectiveness of an AEB （automated emergency braking） system to avoid accidents or reduce the injury severity in rear-end crashes. A method to estimate the friction potential based on on-board sensor information is shown in this work. This work expands the scope of existing investigations on whether the accuracy needed for the warning and intervention strategies of AEB can be reached with the proposed method. First, the bandwidth of surface conditions investigated is extended by including low friction surfaces comparable to ice. Second, situations of changing surface conditions and wheel-individual surface conditions were evaluated. Finally, estimation based on different sensor sets was conducted with regard to series application. The investigations are based on measurements performed on a proving ground. The main emphasis was placed on estimation during longitudinal driving conditions. The used sensors include advanced vehicle dynamics measurement equipment as well as standard on-board sensors of the vehicle.
基金Supported by the National Natural Science Foundation of China (No.60874063)Science and Technology Re-search Foundation of Heilongjiang Education Department (No.11523037)
文摘White noise deconvolution or input white noise estimation problem has important appli-cation backgrounds in oil seismic exploration,communication and signal processing.By the modern time series analysis method,based on the Auto-Regressive Moving Average(ARMA) innovation model,under the linear minimum variance optimal fusion rules,three optimal weighted fusion white noise deconvolution estimators are presented for the multisensor systems with time-delayed measurements and colored measurement noises.They can handle the input white noise fused filtering,prediction and smoothing problems.The accuracy of the fusers is higher than that of each local white noise estimator.In order to compute the optimal weights,the formula of computing the local estimation error cross-covariances is given.A Monte Carlo simulation example for the system with 3 sensors and the Bernoulli-Gaussian input white noise shows their effectiveness and performances.
文摘目的:以MRI测定的全肝脏质子密度脂肪分数(PDFF)为标准,探讨MRI可变容积加速肝脏采集(LAVA-Flex)技术和非对称回波最小二乘估算法迭代水脂分离(IDEAL-IQ)技术测定的代谢相关脂肪性肝病(MAFLD)患者的水相、脂相图肝脏脂肪分数(FF)与PDFF的一致性。探讨LAVA-Flex技术行全肝脏脂肪定量快速检测的可行性。方法:收集97例MAFLD患者及23例健康志愿者。在GE 1.5 T MRI扫描仪上行IDEAL-IQ和LAVA-Flex序列扫描,前者得出PDFF、R2*、水相、脂相、同相位、反相位图,后者得出水相、脂相、同相位、反相位图。使用3D Slicer软件对PDFF、水相、脂相图进行全肝勾画,计算全肝各水相、脂相图的脂肪信号分数(FF_(IQ))和(FF_(Flex))。根据PDFF将120例分成4组:正常组23例,PDFF<5%;轻度组15例,5%≤PDFF<10%;中度组48例,10%≤PDFF<25%;重度组34例,PDFF≥25%。使用Pearson相关性分析评估4组FF_(IQ)、FF_(Flex)与PDFF的一致性,并绘制相关性热图及Bland-Altman图。结果:总体FF_(Flex)与PDFF呈极强相关(r=0.959);正常组FF_(IQ)与PDFF呈极强的相关(r=0.991,P<0.01);轻度组FF_(IQ)与PDFF呈较强相关(r=0.848,P<0.01);中度组FF_(IQ)与PDFF呈极强相关(r=0.997,P<0.01),FF_(Flex)与PDFF呈较强相关(r=0.756,P<0.01);重度组FF_(IQ)、FF_(Flex)均与PDFF呈显著相关(r=0.779,0.793;均P<0.01)。Bland-Altman图显示,FF_(Flex)与FF_(IQ)大部分数据点均落在一致性限内,且中心线接近0,两者与PDFF均具有很好的一致性。结论:IDEAL-IQ和LAVA-Flex技术测定的全肝FF与PDFF呈高度一致性,尤其是在中、重度脂肪肝患者中表现更佳,LAVA-Flex技术以其快速成像的优势为临床肝脏脂肪含量的测定提供了重要工具。
基金supported by the Joint Funds of the National Natural Science Foundation of China under Grant U22A2009in part by the National Key Research and Development Program under Grant 2021YFC2803000.
文摘Sonar locates underwater targets by receiving reflected sound waves.However,the complex marine environment makes it difficult to set targets in appropriate locations and conditions.The sonar echo simulator has the function of simulating sonar detection target echo signals.As a cutting-edge technology,underwater backscatter has led to the emergence of array based acoustic reflection systems.The research on sonar echo simulators based on backscatter technology has promoted the solution of problems such as target echo modeling,sonar arrival direction estimation,and echo directional transmission.In response to the above problems,this paper designs an end-to-end sonar echo simulator system array phase estimation sonar echo simulation system(APE-SESS),which can independently complete highresolution real-time direction of arrival(DOA)estimation and generate directional simulation echo based on the array structure.Dual branch convolutional neural network(DB-CNN)is proposed in the system to estimate the direction of the signal array and directly obtain the phase weights containing azimuth information.Comparing DBCNN with conventional methods and classic underwater DOA network models based on classification problems,the results show that DB-CNN exhibits stability,small error,and high real-time performance under different signal-to-noise ratio(SNR).The proposed APE-SESS has end-to-end characteristics,real-time angle estimation,and azimuth simulation functions.
基金supported by National Natural Science Foundation of China(No.61034005)
文摘This paper presents an Ethernet based hybrid method for predicting random time-delay in the networked control system.First,db3 wavelet is used to decompose and reconstruct time-delay sequence,and the approximation component and detail components of time-delay sequences are fgured out.Next,one step prediction of time-delay is obtained through echo state network(ESN)model and auto-regressive integrated moving average model(ARIMA)according to the diferent characteristics of approximate component and detail components.Then,the fnal predictive value of time-delay is obtained by summation.Meanwhile,the parameters of echo state network is optimized by genetic algorithm.The simulation results indicate that higher accuracy can be achieved through this prediction method.
