This paper explores the recovery of block sparse signals in frame-based settings using the l_(2)/l_(q)-synthesis technique(0<q≤1).We propose a new null space property,referred to as block D-NSP_(q),which is based ...This paper explores the recovery of block sparse signals in frame-based settings using the l_(2)/l_(q)-synthesis technique(0<q≤1).We propose a new null space property,referred to as block D-NSP_(q),which is based on the dictionary D.We establish that matrices adhering to the block D-NSP_(q)condition are both necessary and sufficient for the exact recovery of block sparse signals via l_(2)/l_(q)-synthesis.Additionally,this condition is essential for the stable recovery of signals that are block-compressible with respect to D.This D-NSP_(q)property is identified as the first complete condition for successful signal recovery using l_(2)/l_(q)-synthesis.Furthermore,we assess the theoretical efficacy of the l2/lq-synthesis method under conditions of measurement noise.展开更多
In airborne array synthetic aperture radar(SAR), the three-dimensional(3D) imaging performance and cross-track resolution depends on the length of the equivalent array. In this paper, Barker sequence criterion is used...In airborne array synthetic aperture radar(SAR), the three-dimensional(3D) imaging performance and cross-track resolution depends on the length of the equivalent array. In this paper, Barker sequence criterion is used for sparse flight sampling of airborne array SAR, in order to obtain high cross-track resolution in as few times of flights as possible. Under each flight, the imaging algorithm of back projection(BP) and the data extraction method based on modified uniformly redundant arrays(MURAs) are utilized to obtain complex 3D image pairs. To solve the side-lobe noise in images, the interferometry between each image pair is implemented, and compressed sensing(CS) reconstruction is adopted in the frequency domain. Furthermore, to restore the geometrical relationship between each flight, the phase information corresponding to negative MURA is compensated on each single-pass image reconstructed by CS. Finally,by coherent accumulation of each complex image, the high resolution in cross-track direction is obtained. Simulations and experiments in X-band verify the availability.展开更多
The theory of compressed sensing （CS） provides a new chance to reduce the data acquisition time and improve the data usage factor of the stepped frequency radar system. In light of the sparsity of radar target refle...The theory of compressed sensing （CS） provides a new chance to reduce the data acquisition time and improve the data usage factor of the stepped frequency radar system. In light of the sparsity of radar target reflectivity, two imaging methods based on CS, termed the CS-based 2D joint imaging algorithm and the CS-based 2D decoupled imaging algorithm, are proposed. These methods incorporate the coherent mixing operation into the sparse dictionary, and take random measurements in both range and azimuth directions to get high resolution radar images, thus can remarkably reduce the data rate and simplify the hardware design of the radar system while maintaining imaging quality. Ex- periments from both simulated data and measured data in the anechoic chamber show that the proposed imaging methods can get more focused images than the traditional fast Fourier trans- form method. Wherein the joint algorithm has stronger robustness and can provide clearer inverse synthetic aperture radar images, while the decoupled algorithm is computationally more efficient but has slightly degraded imaging quality, which can be improved by increasing measurements or using a robuster recovery algorithm nevertheless.展开更多
High resolution range imaging with correlation processing suffers from high sidelobe pedestal in random frequency-hopping wideband radar. After the factors which affect the sidelobe pedestal being analyzed, a compress...High resolution range imaging with correlation processing suffers from high sidelobe pedestal in random frequency-hopping wideband radar. After the factors which affect the sidelobe pedestal being analyzed, a compressed sensing based algorithm for high resolution range imaging and a new minimized ll-norm criterion for motion compensation are proposed. The random hopping of the transmitted carrier frequency is converted to restricted isometry property of the observing matrix. Then practical problems of imaging model solution and signal parameter design are resolved. Due to the particularity of the proposed algorithm, two new indicators of range profile, i.e., average signal to sidelobe ratio and local similarity, are defined. The chamber measured data are adopted to testify the validity of the proposed algorithm, and simulations are performed to analyze the precision of velocity measurement as well as the performance of motion compensation. The simulation results show that the proposed algorithm has such advantages as high precision velocity measurement, low sidelobe and short period imaging, which ensure robust imaging for moving targets when signal-to-noise ratio is above 10 dB.展开更多
A compressed sensing（CS） based channel estimation algorithm is proposed by using the delay-Doppler sparsity of the fast fading channel.A compressive basis expansion channel model with sparsity in both time and frequ...A compressed sensing（CS） based channel estimation algorithm is proposed by using the delay-Doppler sparsity of the fast fading channel.A compressive basis expansion channel model with sparsity in both time and frequency domains is given.The pilots in accordance with a novel random pilot matrix in both time and frequency domains are sent to measure the delay-Doppler sparsity channel.The relatively nonzero channel coefficients are tracked by random pilots at a sampling rate significantly below the Nyquist rate.The sparsity channels are estimated from a very limited number of channel measurements by the basis pursuit algorithm.The proposed algorithm can effectively improve the channel estimation performance when the number of pilot symbols is reduced with improvement of throughput efficiency.展开更多
Signal reconstruction is a significantly important theoretical issue for compressed sensing.Considering the situation of signal reconstruction with unknown sparsity,the conventional signal reconstruction algorithms us...Signal reconstruction is a significantly important theoretical issue for compressed sensing.Considering the situation of signal reconstruction with unknown sparsity,the conventional signal reconstruction algorithms usually perform low accuracy.In this work,a sparsity adaptive signal reconstruction algorithm using sensing dictionary is proposed to achieve a lower reconstruction error.The sparsity estimation method is combined with the construction of the support set based on sensing dictionary.Using the adaptive sparsity method,an iterative signal reconstruction algorithm is proposed.The sufficient conditions for the exact signal reconstruction of the algorithm also is proved by theory.According to a series of simulations,the results show that the proposed method has higher precision compared with other state-of-the-art signal reconstruction algorithms especially in a high compression ratio scenarios.展开更多
An imaging algorithm based on compressed sensing（CS） for the multi-ship motion target is presented. In order to reduce the quantity of data transmission in searching the ships on a large sea area, both range and azi...An imaging algorithm based on compressed sensing（CS） for the multi-ship motion target is presented. In order to reduce the quantity of data transmission in searching the ships on a large sea area, both range and azimuth of the moving ship targets are converted into sparse representation under certain signal basis. The signal reconstruction algorithm based on CS at a distant calculation station, and the Keystone and fractional Fourier transform（FRFT） algorithm are used to compensate range migration and obtain Doppler frequency. When the sea ships satisfy the sparsity, the algorithm can obtain higher resolution in both range and azimuth than the conventional imaging algorithm. Some simulations are performed to verify the reliability and stability.展开更多
The use of underwater acoustic data has rapidly expanded with the application of multichannel, large-aperture underwater detection arrays. This study presents an underwater acoustic data compression method that is bas...The use of underwater acoustic data has rapidly expanded with the application of multichannel, large-aperture underwater detection arrays. This study presents an underwater acoustic data compression method that is based on compressed sensing. Underwater acoustic signals are transformed into the sparse domain for data storage at a receiving terminal, and the improved orthogonal matching pursuit(IOMP) algorithm is used to reconstruct the original underwater acoustic signals at a data processing terminal. When an increase in sidelobe level occasionally causes a direction of arrival estimation error, the proposed compression method can achieve a 10 times stronger compression for narrowband signals and a 5 times stronger compression for wideband signals than the orthogonal matching pursuit(OMP) algorithm. The IOMP algorithm also reduces the computing time by about 20% more than the original OMP algorithm. The simulation and experimental results are discussed.展开更多
In the process of image transmission, the famous JPEG and JPEG-2000 compression methods need more transmission time as it is difficult for them to compress the image with a low compression rate. Recently the compresse...In the process of image transmission, the famous JPEG and JPEG-2000 compression methods need more transmission time as it is difficult for them to compress the image with a low compression rate. Recently the compressed sensing（CS） theory was proposed, which has earned great concern as it can compress an image with a low compression rate, meanwhile the original image can be perfectly reconstructed from only a few compressed data. The CS theory is used to transmit the high resolution astronomical image and build the simulation environment where there is communication between the satellite and the Earth. Number experimental results show that the CS theory can effectively reduce the image transmission and reconstruction time. Even with a very low compression rate, it still can recover a higher quality astronomical image than JPEG and JPEG-2000 compression methods.展开更多
目的:探讨三维可变翻转角快速自旋回波(sampling perfection with application optimized contrast using different flip angle evolution,SPACE)序列联合压缩感知(compressed sensing,CS)技术在肩锁关节损伤诊断中的应用价值。方法:...目的:探讨三维可变翻转角快速自旋回波(sampling perfection with application optimized contrast using different flip angle evolution,SPACE)序列联合压缩感知(compressed sensing,CS)技术在肩锁关节损伤诊断中的应用价值。方法:前瞻性地纳入2023年5月—2024年2月在南京医科大学第一附属医院就诊的有肩部外伤史、临床怀疑肩锁关节损伤的患者34例,对患者分别进行常规二维(two-dimension,2D)磁共振序列和基于CS的3D CS-SPACE序列扫描。分别在两组图像上测量肱二头肌长头腱和肱骨骨髓腔的信号强度和标准差,并计算出信噪比(signal to noise ratio,SNR)、对比噪声比(contrast to noise ratio,CNR);3位医生分别通过两组图像评估肩锁关节的损伤情况并给出其诊断信心评级。比较两组图像骨髓腔、肱二头肌长头腱的SNR、CNR以及诊断信心评级;分别分析3位医生在常规2D图像中的诊断一致性和3D CS-SPACE图像中的诊断一致性,最后评估两组图像之间的诊断一致性。结果:图像质量的客观评价中,3D CS-SPACE图像的SNR和CNR均明显优于常规2D图像;两组图像诊断信心的评级,2位医生的3D CS-SPACE图像评级明显高于常规2D图像,1位医生评级差异无统计学意义;3位医生在常规2D图像和3D CS-SPACE图像上对肩锁关节损伤的评估均具有较高的一致性(κ均>0.6),两组图像对肩锁关节的损伤评估具有较高的一致性(κ均>0.6)。结论:对于肩锁关节损伤的诊断,3D CS-SPACE图像与常规2D图像具有较高的一致性,且3D CS-SPACE序列能够在缩短扫描时间的同时获得更好的图像质量。展开更多
Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper ...Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper based on the compressed sensing(CS)theory and sliding window technique,by which the estimates of dropping data packets in the feedback channel are obtained and the performance degradation induced by packet drops is reduced.Specifically,in order to reduce the cumulative error caused by the algorithm,the compensated estimates for single-output systems are corrected via the regularization term;considering the process of single-packet transmission,a new sequential CS framework of sensor data streams is introduced to effectively compensate the dropping packet on single-channel of multi-output systems;in presence of the medium access constraints on multi-channel,the communication sequence for scheduling is coupled to the algorithm and the estimates of the multiple sensors for multi-output systems are obtained via the regularization term.Simulation results illustrate that the proposed methods perform well and receive satisfactory performance.展开更多
A new iterative greedy algorithm based on the backtracking technique was proposed for distributed compressed sensing(DCS) problem. The algorithm applies two mechanisms for precise recovery soft thresholding and cuttin...A new iterative greedy algorithm based on the backtracking technique was proposed for distributed compressed sensing(DCS) problem. The algorithm applies two mechanisms for precise recovery soft thresholding and cutting. It can reconstruct several compressed signals simultaneously even without any prior information of the sparsity, which makes it a potential candidate for many practical applications, but the numbers of non-zero(significant) coefficients of signals are not available. Numerical experiments are conducted to demonstrate the validity and high performance of the proposed algorithm, as compared to other existing strong DCS algorithms.展开更多
目的探讨压缩感知结合层面编码金属伪影校正(compressed sensing-slice-encoding metal artifact correction,CS-SEMAC)技术用于脊柱金属植入物术后MRI的应用价值。材料与方法比较招募的35例脊柱金属植入物术后患者3.0 T MRI矢状位CS-SE...目的探讨压缩感知结合层面编码金属伪影校正(compressed sensing-slice-encoding metal artifact correction,CS-SEMAC)技术用于脊柱金属植入物术后MRI的应用价值。材料与方法比较招募的35例脊柱金属植入物术后患者3.0 T MRI矢状位CS-SEMAC序列、高带宽(high bandwidth,HBW)序列和水脂分离(Dixon)三种序列在金属植入物伪影面积、椎体信噪比(signal-to-noise ratio,SNR)、图像质量、图像清晰度、脂肪抑制效果以及植入物周围解剖结构的可见性方面的差异。结果CS-SEMAC在T1、T2矢状位图像上金属伪影面积分别为(15.45±6.84)、(22.23±9.76)cm^(2),显著低于其他两种序列,差异具有统计学意义(P<0.001);三种序列在T2抑脂矢状面图像上的SNR两两比较显示:HBW序列椎体SNR显著高于其他两种序列,Dixon序列椎体SNR显著低于其他两种序列,CS-SEMAC序列椎体SNR低于HBW序列,高于Dixon序列,差异均有统计学意义(P<0.001);在图像清晰度上,T2WI-tirm-CS-SEMAC序列评分低于其他两种序列,差异具有统计学意义(P<0.001);T2WI-tirm-CS-SEMAC序列在图像质量和脂肪抑制效果方面评分显著优于其他两种序列,差异具有统计学意义(P<0.001);并且CS-SEMAC序列相较于其他两种序列更能清晰显示植入物周围椎体、椎弓根、椎间孔及神经根,差异具有统计学意义(P<0.001)。结论CS-SEMAC序列相比于HBW、Dixon序列能够有效减少植入物周围的金属伪影,并且能显著提高T2抑脂序列的图像质量和脂肪抑制效果,虽然在T2抑脂上金属植入物邻近椎体SNR相比HBW序列有所下降,图像比HBW和Dixon图像略模糊,但是椎体周围关键解剖结构的可见度明显提升,对脊柱术后解剖结构的显示有一定优势。展开更多
太赫兹成像技术虽已被证实能够用于检测葵花籽内部品质,然而其成像速度较为缓慢,难以实现切实且迅速的检测。为了实现对葵花籽饱满度的快速检测,该研究将压缩感知与注意力增强超分辨率生成对抗网络(A-ESRGAN)模型相结合应用于太赫兹成...太赫兹成像技术虽已被证实能够用于检测葵花籽内部品质,然而其成像速度较为缓慢,难以实现切实且迅速的检测。为了实现对葵花籽饱满度的快速检测,该研究将压缩感知与注意力增强超分辨率生成对抗网络(A-ESRGAN)模型相结合应用于太赫兹成像领域。首先,选用压缩采样匹配追踪(compressive sampling matching pursuit,CoSaMP)重构算法来验证不同测量矩阵的性能,根据最佳综合性能选取高斯矩阵作为测量矩阵。其次,通过比较基于交替方向乘子法(alternating direction method of multipliers,ADMM)结合全变分(total variation,TV)正则化(ADMM_TV)和子空间追踪(subspace pursuit,SP)等5种重构算法的峰值信噪比和重构时间等评价指标评估图像重建质量。结果表明ADMM_TV在峰值信噪比、均方误差、结构相似性指数表现最佳,自然图像质量评估器在测量比例超过6.0%最低,尽管重构时间无明显优势,但综合表现优于其他算法。最后,运用多尺度注意力增强超分辨率生成对抗网络(A-ESRGANmulti)模型对压缩感知不同采样率的重构图像进行处理,其效果优于真实图像增强超分辨率生成对抗网络(RealESRGAN)和单尺度注意力增强超分辨率生成对抗网络(A-ESRGAN-single),提升了图像质量,使边缘对比度得以提高,为后续的图像分割提供了便利。研究表明,压缩感知与A-ESRGAN-multi模型相结合用于检测葵花籽饱满度是可行的,验证集的饱满度误差平均为2.50%,最大检测误差为6.41%。综上所述,将压缩感知与A-ESRGAN-multi模型相结合,能够有效地节省82.5%的采样时间,为葵花籽的品质检测开辟了新的途径。展开更多
基金Supported by The Featured Innovation Projects of the General University of Guangdong Province(2023KTSCX096)The Special Projects in Key Areas of Guangdong Province(ZDZX1088)Research Team Project of Guangdong University of Education(2024KYCXTD018)。
文摘This paper explores the recovery of block sparse signals in frame-based settings using the l_(2)/l_(q)-synthesis technique(0<q≤1).We propose a new null space property,referred to as block D-NSP_(q),which is based on the dictionary D.We establish that matrices adhering to the block D-NSP_(q)condition are both necessary and sufficient for the exact recovery of block sparse signals via l_(2)/l_(q)-synthesis.Additionally,this condition is essential for the stable recovery of signals that are block-compressible with respect to D.This D-NSP_(q)property is identified as the first complete condition for successful signal recovery using l_(2)/l_(q)-synthesis.Furthermore,we assess the theoretical efficacy of the l2/lq-synthesis method under conditions of measurement noise.
文摘In airborne array synthetic aperture radar(SAR), the three-dimensional(3D) imaging performance and cross-track resolution depends on the length of the equivalent array. In this paper, Barker sequence criterion is used for sparse flight sampling of airborne array SAR, in order to obtain high cross-track resolution in as few times of flights as possible. Under each flight, the imaging algorithm of back projection(BP) and the data extraction method based on modified uniformly redundant arrays(MURAs) are utilized to obtain complex 3D image pairs. To solve the side-lobe noise in images, the interferometry between each image pair is implemented, and compressed sensing(CS) reconstruction is adopted in the frequency domain. Furthermore, to restore the geometrical relationship between each flight, the phase information corresponding to negative MURA is compensated on each single-pass image reconstructed by CS. Finally,by coherent accumulation of each complex image, the high resolution in cross-track direction is obtained. Simulations and experiments in X-band verify the availability.
基金supported by the Prominent Youth Fund of the National Natural Science Foundation of China (61025006)
文摘The theory of compressed sensing （CS） provides a new chance to reduce the data acquisition time and improve the data usage factor of the stepped frequency radar system. In light of the sparsity of radar target reflectivity, two imaging methods based on CS, termed the CS-based 2D joint imaging algorithm and the CS-based 2D decoupled imaging algorithm, are proposed. These methods incorporate the coherent mixing operation into the sparse dictionary, and take random measurements in both range and azimuth directions to get high resolution radar images, thus can remarkably reduce the data rate and simplify the hardware design of the radar system while maintaining imaging quality. Ex- periments from both simulated data and measured data in the anechoic chamber show that the proposed imaging methods can get more focused images than the traditional fast Fourier trans- form method. Wherein the joint algorithm has stronger robustness and can provide clearer inverse synthetic aperture radar images, while the decoupled algorithm is computationally more efficient but has slightly degraded imaging quality, which can be improved by increasing measurements or using a robuster recovery algorithm nevertheless.
基金Project(61171133) supported by the National Natural Science Foundation of ChinaProject(CX2011B019) supported by Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(B110404) supported by Innovation Foundation for Outstanding Postgraduates of National University of Defense Technology,China
文摘High resolution range imaging with correlation processing suffers from high sidelobe pedestal in random frequency-hopping wideband radar. After the factors which affect the sidelobe pedestal being analyzed, a compressed sensing based algorithm for high resolution range imaging and a new minimized ll-norm criterion for motion compensation are proposed. The random hopping of the transmitted carrier frequency is converted to restricted isometry property of the observing matrix. Then practical problems of imaging model solution and signal parameter design are resolved. Due to the particularity of the proposed algorithm, two new indicators of range profile, i.e., average signal to sidelobe ratio and local similarity, are defined. The chamber measured data are adopted to testify the validity of the proposed algorithm, and simulations are performed to analyze the precision of velocity measurement as well as the performance of motion compensation. The simulation results show that the proposed algorithm has such advantages as high precision velocity measurement, low sidelobe and short period imaging, which ensure robust imaging for moving targets when signal-to-noise ratio is above 10 dB.
基金supported by the National Natural Science Foundation of China(60972056)the Innovation Foundation of Shanghai Education Committee(09ZZ89)Shanghai Leading Academic Discipline Project and STCSM(S30108and08DZ2231100)
文摘A compressed sensing（CS） based channel estimation algorithm is proposed by using the delay-Doppler sparsity of the fast fading channel.A compressive basis expansion channel model with sparsity in both time and frequency domains is given.The pilots in accordance with a novel random pilot matrix in both time and frequency domains are sent to measure the delay-Doppler sparsity channel.The relatively nonzero channel coefficients are tracked by random pilots at a sampling rate significantly below the Nyquist rate.The sparsity channels are estimated from a very limited number of channel measurements by the basis pursuit algorithm.The proposed algorithm can effectively improve the channel estimation performance when the number of pilot symbols is reduced with improvement of throughput efficiency.
基金supported by the National Natural Science Foundation of China(61773202,71874081)the Special Financial Grant from China Postdoctoral Science Foundation(2017T100366)+2 种基金the Key Laboratory of Avionics System Integrated Technology for National Defense Science and Technology,China Institute of Avionics Radio Electronics(6142505180407)the Open Fund of CAAC Key laboratory of General Aviation Operation,Civil Aviation Management Institute of China(CAMICKFJJ-2019-04)the Innovation Project of the Civil Aviation Administration of China(EAB19001)。
文摘Signal reconstruction is a significantly important theoretical issue for compressed sensing.Considering the situation of signal reconstruction with unknown sparsity,the conventional signal reconstruction algorithms usually perform low accuracy.In this work,a sparsity adaptive signal reconstruction algorithm using sensing dictionary is proposed to achieve a lower reconstruction error.The sparsity estimation method is combined with the construction of the support set based on sensing dictionary.Using the adaptive sparsity method,an iterative signal reconstruction algorithm is proposed.The sufficient conditions for the exact signal reconstruction of the algorithm also is proved by theory.According to a series of simulations,the results show that the proposed method has higher precision compared with other state-of-the-art signal reconstruction algorithms especially in a high compression ratio scenarios.
基金supported by the National Natural Science Foundation of China(61271342)
文摘An imaging algorithm based on compressed sensing（CS） for the multi-ship motion target is presented. In order to reduce the quantity of data transmission in searching the ships on a large sea area, both range and azimuth of the moving ship targets are converted into sparse representation under certain signal basis. The signal reconstruction algorithm based on CS at a distant calculation station, and the Keystone and fractional Fourier transform（FRFT） algorithm are used to compensate range migration and obtain Doppler frequency. When the sea ships satisfy the sparsity, the algorithm can obtain higher resolution in both range and azimuth than the conventional imaging algorithm. Some simulations are performed to verify the reliability and stability.
基金Project(11174235)supported by the National Natural Science Foundation of ChinaProject(3102014JC02010301)supported by the Fundamental Research Funds for the Central Universities,China
文摘The use of underwater acoustic data has rapidly expanded with the application of multichannel, large-aperture underwater detection arrays. This study presents an underwater acoustic data compression method that is based on compressed sensing. Underwater acoustic signals are transformed into the sparse domain for data storage at a receiving terminal, and the improved orthogonal matching pursuit(IOMP) algorithm is used to reconstruct the original underwater acoustic signals at a data processing terminal. When an increase in sidelobe level occasionally causes a direction of arrival estimation error, the proposed compression method can achieve a 10 times stronger compression for narrowband signals and a 5 times stronger compression for wideband signals than the orthogonal matching pursuit(OMP) algorithm. The IOMP algorithm also reduces the computing time by about 20% more than the original OMP algorithm. The simulation and experimental results are discussed.
文摘In the process of image transmission, the famous JPEG and JPEG-2000 compression methods need more transmission time as it is difficult for them to compress the image with a low compression rate. Recently the compressed sensing（CS） theory was proposed, which has earned great concern as it can compress an image with a low compression rate, meanwhile the original image can be perfectly reconstructed from only a few compressed data. The CS theory is used to transmit the high resolution astronomical image and build the simulation environment where there is communication between the satellite and the Earth. Number experimental results show that the CS theory can effectively reduce the image transmission and reconstruction time. Even with a very low compression rate, it still can recover a higher quality astronomical image than JPEG and JPEG-2000 compression methods.
文摘目的:探讨三维可变翻转角快速自旋回波(sampling perfection with application optimized contrast using different flip angle evolution,SPACE)序列联合压缩感知(compressed sensing,CS)技术在肩锁关节损伤诊断中的应用价值。方法:前瞻性地纳入2023年5月—2024年2月在南京医科大学第一附属医院就诊的有肩部外伤史、临床怀疑肩锁关节损伤的患者34例,对患者分别进行常规二维(two-dimension,2D)磁共振序列和基于CS的3D CS-SPACE序列扫描。分别在两组图像上测量肱二头肌长头腱和肱骨骨髓腔的信号强度和标准差,并计算出信噪比(signal to noise ratio,SNR)、对比噪声比(contrast to noise ratio,CNR);3位医生分别通过两组图像评估肩锁关节的损伤情况并给出其诊断信心评级。比较两组图像骨髓腔、肱二头肌长头腱的SNR、CNR以及诊断信心评级;分别分析3位医生在常规2D图像中的诊断一致性和3D CS-SPACE图像中的诊断一致性,最后评估两组图像之间的诊断一致性。结果:图像质量的客观评价中,3D CS-SPACE图像的SNR和CNR均明显优于常规2D图像;两组图像诊断信心的评级,2位医生的3D CS-SPACE图像评级明显高于常规2D图像,1位医生评级差异无统计学意义;3位医生在常规2D图像和3D CS-SPACE图像上对肩锁关节损伤的评估均具有较高的一致性(κ均>0.6),两组图像对肩锁关节的损伤评估具有较高的一致性(κ均>0.6)。结论:对于肩锁关节损伤的诊断,3D CS-SPACE图像与常规2D图像具有较高的一致性,且3D CS-SPACE序列能够在缩短扫描时间的同时获得更好的图像质量。
基金supported by the National Key Research and Development Plan(2018YFB1201601-12)。
文摘Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper based on the compressed sensing(CS)theory and sliding window technique,by which the estimates of dropping data packets in the feedback channel are obtained and the performance degradation induced by packet drops is reduced.Specifically,in order to reduce the cumulative error caused by the algorithm,the compensated estimates for single-output systems are corrected via the regularization term;considering the process of single-packet transmission,a new sequential CS framework of sensor data streams is introduced to effectively compensate the dropping packet on single-channel of multi-output systems;in presence of the medium access constraints on multi-channel,the communication sequence for scheduling is coupled to the algorithm and the estimates of the multiple sensors for multi-output systems are obtained via the regularization term.Simulation results illustrate that the proposed methods perform well and receive satisfactory performance.
基金Projects(61203287,61302138,11126274)supported by the National Natural Science Foundation of ChinaProject(2013CFB414)supported by Natural Science Foundation of Hubei Province,ChinaProject(CUGL130247)supported by the Special Fund for Basic Scientific Research of Central Colleges of China University of Geosciences
文摘A new iterative greedy algorithm based on the backtracking technique was proposed for distributed compressed sensing(DCS) problem. The algorithm applies two mechanisms for precise recovery soft thresholding and cutting. It can reconstruct several compressed signals simultaneously even without any prior information of the sparsity, which makes it a potential candidate for many practical applications, but the numbers of non-zero(significant) coefficients of signals are not available. Numerical experiments are conducted to demonstrate the validity and high performance of the proposed algorithm, as compared to other existing strong DCS algorithms.
文摘目的探讨压缩感知结合层面编码金属伪影校正(compressed sensing-slice-encoding metal artifact correction,CS-SEMAC)技术用于脊柱金属植入物术后MRI的应用价值。材料与方法比较招募的35例脊柱金属植入物术后患者3.0 T MRI矢状位CS-SEMAC序列、高带宽(high bandwidth,HBW)序列和水脂分离(Dixon)三种序列在金属植入物伪影面积、椎体信噪比(signal-to-noise ratio,SNR)、图像质量、图像清晰度、脂肪抑制效果以及植入物周围解剖结构的可见性方面的差异。结果CS-SEMAC在T1、T2矢状位图像上金属伪影面积分别为(15.45±6.84)、(22.23±9.76)cm^(2),显著低于其他两种序列,差异具有统计学意义(P<0.001);三种序列在T2抑脂矢状面图像上的SNR两两比较显示:HBW序列椎体SNR显著高于其他两种序列,Dixon序列椎体SNR显著低于其他两种序列,CS-SEMAC序列椎体SNR低于HBW序列,高于Dixon序列,差异均有统计学意义(P<0.001);在图像清晰度上,T2WI-tirm-CS-SEMAC序列评分低于其他两种序列,差异具有统计学意义(P<0.001);T2WI-tirm-CS-SEMAC序列在图像质量和脂肪抑制效果方面评分显著优于其他两种序列,差异具有统计学意义(P<0.001);并且CS-SEMAC序列相较于其他两种序列更能清晰显示植入物周围椎体、椎弓根、椎间孔及神经根,差异具有统计学意义(P<0.001)。结论CS-SEMAC序列相比于HBW、Dixon序列能够有效减少植入物周围的金属伪影,并且能显著提高T2抑脂序列的图像质量和脂肪抑制效果,虽然在T2抑脂上金属植入物邻近椎体SNR相比HBW序列有所下降,图像比HBW和Dixon图像略模糊,但是椎体周围关键解剖结构的可见度明显提升,对脊柱术后解剖结构的显示有一定优势。
文摘太赫兹成像技术虽已被证实能够用于检测葵花籽内部品质,然而其成像速度较为缓慢,难以实现切实且迅速的检测。为了实现对葵花籽饱满度的快速检测,该研究将压缩感知与注意力增强超分辨率生成对抗网络(A-ESRGAN)模型相结合应用于太赫兹成像领域。首先,选用压缩采样匹配追踪(compressive sampling matching pursuit,CoSaMP)重构算法来验证不同测量矩阵的性能,根据最佳综合性能选取高斯矩阵作为测量矩阵。其次,通过比较基于交替方向乘子法(alternating direction method of multipliers,ADMM)结合全变分(total variation,TV)正则化(ADMM_TV)和子空间追踪(subspace pursuit,SP)等5种重构算法的峰值信噪比和重构时间等评价指标评估图像重建质量。结果表明ADMM_TV在峰值信噪比、均方误差、结构相似性指数表现最佳,自然图像质量评估器在测量比例超过6.0%最低,尽管重构时间无明显优势,但综合表现优于其他算法。最后,运用多尺度注意力增强超分辨率生成对抗网络(A-ESRGANmulti)模型对压缩感知不同采样率的重构图像进行处理,其效果优于真实图像增强超分辨率生成对抗网络(RealESRGAN)和单尺度注意力增强超分辨率生成对抗网络(A-ESRGAN-single),提升了图像质量,使边缘对比度得以提高,为后续的图像分割提供了便利。研究表明,压缩感知与A-ESRGAN-multi模型相结合用于检测葵花籽饱满度是可行的,验证集的饱满度误差平均为2.50%,最大检测误差为6.41%。综上所述,将压缩感知与A-ESRGAN-multi模型相结合,能够有效地节省82.5%的采样时间,为葵花籽的品质检测开辟了新的途径。
