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Shape Parameter Estimation of K-Distributed Sea Clutter Using Neural Network and Multisample Percentile in Radar Industry

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IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS 2023年第6期19卷 7602-7612页

作者： xue, Jian Sun, Mengling Liu, Jun xu, shuwen Pan, Meiyan Xian Univ Posts & Telecommun Sch Commun & Informat Engn Xian 710122 Peoples R China Univ Sci & Technol China Dept Elect Engn & Informat Sci Hefei 230052 Peoples R China Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Peoples R China Xian Elect Engn Res Inst Xian 710049 Peoples R China

In this paper, we consider the problem of robustly and accurately estimating the shape parameters of K-distributed sea clutter in the maritime radar industry. Outliers formed by non-sea-surface echoes have a significant negative impact on the estimation accuracy. To improve the estimation performance, we first propose a bipercentiles feedforward neural network for the shape parameter eta (BPFFNN-eta), which utilizes a ratio of two percentiles and a twohidden-layer feedforward neural network. The BP-FFNN-eta can learn the mathematical relationship between the shape parameter and the ratio of two percentiles, and can work in environments where the number of outliers is approximately known. Moreover, to solve the case where the number of outliers is not known due to dynamic changes in the environment, we also design another neural network (referred to as MBP-FFNN-eta), which consists of multiple BP-FFNNs-eta and a multi-class classification network. The MBP-FFNN-eta can perceive the change in the proportion of outliers, so an accurate estimate can be obtained from an unaffected BP-FFNN-eta. Finally, training and test data are constructed to train and evaluate the proposed methods, respectively. Experimental results demonstrate that the BPFFNN-eta performs better than traditional moments-based estimators, and has almost the same performance as the tri-percentile estimator. Compared with the tri-percentile estimator, the BP-FFNN-eta avoids table lookups, and produces a continuous estimate. The MBP-FFNN-eta can achieve more than 97% overall classification accuracy on simulated and measured data, and thus an accurate estimate of the shape parameter can be obtained when the number of outliers varies.

关键词： K distribution neural network sample percentiles sea clutter shape parameter estimation

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Adaptive convolutional sparsity with sub-band correlation in the NSCT domain for MRI image fusion

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PHYSICS IN MEDICINE AND BIOLOGY 2024年第5期69卷 055022-055022页

作者： Hu, Qiu Cai, Weiming xu, shuwen Hu, Shaohai Wang, Lang He, Xinyi NingboTech Univ Sch Informat Sci & Engn Ningbo 315100 Peoples R China Zhejiang Engn Res Ctr Intelligent Marine Ranch Eq Ningbo 315100 Peoples R China China Elect Technol Grp Corp Res Inst 3 Beijing 100846 Peoples R China Beijing Jiaotong Univ Inst Informat Sci Beijing 100044 Peoples R China Beijing Key Lab Adv Informat Sci & Network Techno Beijing 100044 Peoples R China Ningbo Xiaoshi High Sch Ningbo 315100 Peoples R China

Objective. Multimodal medical image fusion (MMIF) technologies merges diverse medical images with rich information, boosting diagnostic efficiency and accuracy. Due to global optimization and single-valued nature, convolutional sparse representation (CSR) outshines the standard sparse representation (SR) in significance. By addressing the challenges of sensitivity to highly redundant dictionaries and robustness to misregistration, an adaptive convolutional sparsity scheme with measurement of the sub-band correlation in the non-subsampled contourlet transform (NSCT) domain is proposed for MMIF. Approach. The fusion scheme incorporates four main components: image decomposition into two scales, fusion of detail layers, fusion of base layers, and reconstruction of the two scales. We solved a Tikhonov regularization optimization problem with source images to obtain the base and detail layers. Then, after CSR processing, detail layers were sparsely decomposed using pre-trained dictionary filters for initial coefficient maps. NSCT domain's sub-band correlation was used to refine fusion coefficient maps, and sparse reconstruction produced the fused detail layer. Meanwhile, base layers were fused using averaging. The final fused image was obtained via two-scale reconstruction. Main results. Experimental validation of clinical image sets revealed that the proposed fusion scheme can not only effectively eliminate the interference of partial misregistration, but also outperform the representative state-of-the-art fusion schemes in the preservation of structural and textural details according to subjective visual evaluations and objective quality evaluations. Significance. The proposed fusion scheme is competitive due to its low-redundancy dictionary, robustness to misregistration, and better fusion performance. This is achieved by training the dictionary with minimal samples through CSR to adaptively preserve overcompleteness for detail layers, and constructing fusion activity

关键词： multimodal medical image image fusion sparse representation convolutional sparse representation non-subsampled contourlet transform misregistration

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Adaptive Bayesian Detection for Multistatic Radar in Compound-Gaussian Clutter with Inverse Gaussian Texture 15

Adaptive Bayesian Detection for Multistatic Radar in Compoun...

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15th International Conference on Signal Processing Systems, ICSPS 2023

作者： Zhou, Hao xu, shuwen Cui, Yaosheng National Key Laboratory of Radar Signal Processing Xidian University No. 2 South Taibai Road Shaanxi Xi’an710071 China

ISBN: (纸本)9781510675056

This work addresses the problem of adaptive target detection in compound-Gaussian clutter for multistatic radar. We exploit a-priori knowledge of the clutter to alleviate the performance degradation due to the non-Gaussian characteristic of the clutter. Here, the inverse Gaussian distribution is adopted to describe the texture of the clutter. In addition, the speckle covariance matrix of the clutter is modeled as a random matrix following the complex inverse Wishart distribution. Using different fusion rules between the a-priori knowledge of the texture and the speckle component within the Bayesian framework, two adaptive detectors are derived based on the Generalized Likelihood Ratio Test (GLRT) criterion. Finally, the detection performance of the proposed detectors is verified using simulated data. The results show the superiority of the proposed adaptive detectors over the existing techniques. © 2024 SPIE.

关键词： Textures

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Floating Small Target Detection in Sea Clutter Based on Multifeature Angle Variance

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IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2023年 16卷 9849-9863页

作者： Bai, Xiaohui xu, shuwen Zhu, Jianan Guo, Zixun Shui, Penglang Xidian Univ Natl Key Lab Radar Signal Proc Xian 710071 Peoples R China Shenyang Aircraft Design & Res Inst AVIC Shenyang 110000 Peoples R China Northwestern Polytech Univ Sch Elect & Informat Xian 710072 Peoples R China

Amid radar target detection fields, the detection of small floating targets in sea clutter is a tough but crucial task. An efficient solution to address the issue is feature-based detection method based on distinguishable features extracted from sea clutter and returns with target. Nevertheless, as the number of features increases, traditional algorithms with dimension limitation are not adaptable to combine the multiple features to detect. In this article, angle variance-based anomaly detection algorithms which solve the problem of the "curse of dimensionality" are introduced into floating small target detection. An improved algorithm by using the Mahalanobis distance is proposed and for the purpose of detecting the sea-surface small target, a novel detector with controlled false alarm capability is developed. On the open and recognized databases, the detection abilities of the proposed detector are assessed. It is confirmed that the proposed multifeature angle variance-based detector is more effective than other detectors based on multifeature distance or density from experimental results. This proposed detector can implement the improvement of detection performance with less computational cost compared to other well-established detectors.

关键词： Feature extraction Detectors Clutter Radar Radar detection Object detection Radar cross-sections Angle variance anomaly detection feature-based detection floating small target detection Sea clutter

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An Efficient Method for Estimating Complex High-resolution Range Profiles of Ships 15

An Efficient Method for Estimating Complex High-resolution R...

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15th International Conference on Signal Processing Systems, ICSPS 2023

作者： Su, Hailong Shui, Penglang xu, shuwen National Key Laboratory of Radar Signal Processing Xidian University Xi’an710071 China

ISBN: (纸本)9781510675056

High-resolution range profiles (HRRPs) of ships are significant for ship classification and recognition, sparse recovery methods are a major tool to attain ship HRRPs from high-resolution radar echoes. Aiming at the problem that complex HRRPs of ships are not finely modeled in the sparse recovery via iterative minimization (SRIM) method, this paper proposes a new SRIM method to estimate complex HRRPs of ships from radar echoes corrupted by non-Gaussian sea clutter. In the new SRIM method, ship HRRPs are modeled by a bi-parametric lognormal distribution (LND), and high-resolution sea clutter is characterized by the compound-Gaussian distribution with inverse Gaussian texture (CG-IG). The new SRIM method is compared with the classic sparse learning via iterative minimization (SLIM) method, the linear programming-based (LP-based) method, and the recent SRIM method by adopting simulated and measured radar data, the experimental results show that the new SRIM method effectively reduces the central processing unit (CPU) time of ship HRRP estimation while attaining better performance than the existing methods. © 2024 SPIE.

关键词： Ships

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Dual-polarimetric Fusion MTD in Sea Clutter with Inverse Gamma Texture 15

Dual-polarimetric Fusion MTD in Sea Clutter with Inverse Gam...

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15th International Conference on Signal Processing Systems, ICSPS 2023

作者： Duan, Tingyu Shui, Penglang xu, shuwen National Key Laboratory of Radar Signal Processing Xidian University Xi’an710071 China

ISBN: (纸本)9781510675056

Polarimetric radar is significant in radar signal processing to improve the detection performance. The research and development of target detection methods in multi-polarization channels have positive significance in complicated marine environments. In this paper, we present the problem of polarization diversity detection in compound Gaussian sea clutter with inverse Gamma texture. In this respect, a fusion detector using HH and HV dual-polarization data is proposed to detect targets in the compound-Gaussian clutter with inverse Gamma texture. On the basis of the shape parameter matched MTD detector, the test statistics of different channels are weighted and fused by using the signal-to-clutter ratio information of sea clutter. In this way, a new detector is obtained. Thresholds of the detector are calculated by Monte Carlo experiments. Numerical results of real measured radar data show that the proposed detector outperforms its competitors. © 2024 SPIE.

关键词： Textures

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A Distributed Algorithm for Reconstructing Time-Varying Graph Signals

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CIRCUITS SYSTEMS AND SIGNAL PROCESSING 2022年第6期41卷 3624-3641页

作者： Chi, Yuan Jiang, Junzheng Zhou, Fang xu, shuwen Guilin Univ Elect Technol Guangxi Key Lab Wireless Wideband Commun & Signal Guilin 541004 Peoples R China Guilin Univ Elect Technol Sch Life & Environm Sci Guilin 541004 Peoples R China Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Peoples R China

The reconstruction of time-varying signals on graphs is a prominent problem in graph signal processing community. By imposing the smoothness regularization over the time-vertex domain, the reconstruction problem can be formulated into an unconstrained optimization problem that minimizes the weighted sum of the data fidelity term and regularization term. In this paper, we propose an approximate Newton method to solve the problem in a distributed manner, which is applicable for spatially distributed systems consisting of agents with limited computation and communication capacity. The algorithm has low computational complexity while nearly maintains the fast convergence of the second-order methods, which is evidently better than the existing reconstruction algorithm based on the gradient descent method. The convergence of the proposed algorithm is explicitly proved. Numerical results verify the validity and fast convergence of the proposed algorithm.

关键词： Time-varying graph signal reconstruction Distributed algorithm Matrix inverse approximation

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Experimental study on replacement behavior of crude oil by CO2 based on nuclear magnetic resonance technology

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JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY 2024年第3期45卷 449-460页

作者： Li, Baiyang Mou, Jianye xu, shuwen Zhang, Shicheng Ma, Xinfang Zou, Yushi Wang, Fei China Univ Petr State Key Lab Petr Resources & Prospecting Beijing Peoples R China CNPC Oil Prod Plant Huabei Oilfield 4 Langfang Peoples R China

Due to the high viscosity of Jimsar crude oil and the lipophilicity of the reservoir, CO2 has an excellent performance in development of Jimsar shale oil. However, previous studies mostly focused on CO2 fracturing, but the replacement of crude oil by CO2 is rarely reported. Therefore, we conducted research on oil replacement by CO2 through systematical experiments. Firstly, we designed an experimental approach based on nuclear magnetic resonance to quantify the replacement ratio of oil. Next, a series of experiments were conducted for analyzing the effect of pressure, soaking time, permeability, and fractures on replacement ratio. Finally, oil-water imbibition experiments were conducted to compare its development effect with CO2 replacement for target reservoir. The study shows that the replacement capacity of CO2 for crude oil increases with pressure. In the experiment, the replacement ratio increases from 27.46% (10 MPa) to 56.70% (40 MPa) after 24 hours. On the microscopic scale, the crude oil in large pores is replaced out firstly, then the smaller pores. And on the macroscopic scale, the replacement of crude oil is from outside to inside. High permeability and fractures in the core promote the intrusion of CO2 into the core, raising the replacement ratio significantly. Since Jimsar reservoir is oil-wet, the oil recovery of oil-water imbibition is far less than that of CO2 replacement. The minimum pore through which oil can be exploited by oil-water imbibition is 1 mu m, while for CO2 replacement the value is 0.08 mu m. This study provides fundamental for CO2 increasing oil recovery in Jimsar shale oil.

关键词： Jimsar shale soaking experiment replacement of crude oil by CO2 nuclear magnetic resonance T2 spectrum oil-water imbibition

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Optimum and Near-Optimum Coherent CFAR Detection of Radar Targets in Compound-Gaussian Clutter With Generalized Inverse Gaussian Texture

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2022年第3期58卷 1692-1706页

作者： xu, shuwen Wang, Zhexiang Bai, Xiaohui Zhou, Hao Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Peoples R China Xidian Univ Collaborat Innovat Ctr Informat Sensing & Unders Xian 710071 Peoples R China

In this article, we propose optimum and near-optimum adaptive coherent detectors of radar targets in compound-Gaussian clutter with generalized inverse Gaussian texture (CG-GIG clutter). The target amplitude and the speckle covariance matrix are modeled as unknown quantities to be estimated. On the basis of the two-step generalized likelihood ratio test (GLRT) and the estimate of the speckle covariance matrix, the optimum coherent detector and its adaptive version are designed in this article. It is demonstrated that the proposed optimum coherent detector contains three common detectors, which are the optimum K detector, the generalized likelihood ratio test linear-threshold detector (GLRT-LTD), and the GLRT detector for compound-Gaussian clutter with inverse Gaussian texture. Due to the existence of the modified Bessel function depending on data, the optimum coherent detector is computationally unrealizable. Therefore, a near-optimum coherent detector with a new structure named $\alpha$ matched filter ($\alpha$-MF) detector and its adaptive version are proposed, which decreases the computational cost. The proposed near-optimum coherent detector contains two common detectors, the GLRT-LTD and the $\alpha$-MF detector in K-distributed clutter, and has a comparable detection performance of the near-optimum detector in compound-Gaussian clutter with inverse Gaussian texture, which was proposed before. Theoretical analysis and numerical experiments illustrate that the proposed two detectors for CG-GIG clutter have the constant false alarm ratio property relative to the estimate of the speckle covariance matrix and the Doppler steering vector. Moreover, the detection performance of the two coherent detectors are evaluated by the simulated and real data.

关键词： Clutter Detectors Radar Radar detection Adaptation models Computational modeling Radar clutter Compound-Gaussian clutter generalized inverse Gaussian texture generalized likelihood ratio test (GLRT) near-optimum coherent detector optimum coherent detector

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Synthesis of tetrasubstituted furans through a Cu/base-mediated cascade reaction from terminal alkynes and 1,2-diketones

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ORGANIC & BIOMOLECULAR CHEMISTRY 2025年第5期23卷 1084-1088页

作者： Fan, Jian Liang, xuecheng Yao, Liangliang Wang, Yating Wang, Kai Yao, Bangben Liu, Yujun xu, shuwen Anhui Acad Sci & Technol Hefei 230088 Peoples R China Anhui Prod Qual Supervis & Inspect Res Inst Hefei Peoples R China Chuzhou Univ Sch Mat & Chem Engn Chuzhou 239000 Peoples R China

The expeditious construction of tetrasubstituted furans via Cu/base-promoted cascade reactions of terminal alkynes with 1,2-diketones is described. This reaction proceeds smoothly, involving the formation of multiple chemical bonds tolerating a wide range of functional groups. The mechanism underlying these transformations has been thoroughly investigated, suggesting that 1,3-diyne serves as a key intermediate generated in situ through oxidative coupling facilitated by the Cu catalyst.

关键词： Reaction intermediates

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