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Wideband underwater sonar imaging via compressed sensing with scaling effect compensation

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Science China(Information Sciences) 2015年第2期58卷 68-78页

作者： YAN HuiChen XU Jia xia xiang-gen LIU Feng PENG ShiBao ZHANG XuDong LONG Teng Department of Electronic Engineering Tsinghua University School of Information and Electronic Beijing Institute of Technology Department of Electrical and Computer Engineering University of Delaware

By exploiting the sparsity of the imaging scene, compressed sensing(CS) imaging may provide an effective solution to cope with the tradeoff of high azimuth resolution and wide swath in synthetic aperture sonar imaging. However, existing CS imaging methods are based on narrowband signal model and the scaling effect on the echoes is normally omitted, which may seriously affect the ultimate image reconstruction performance.This paper establishes the wideband CS underwater sonar imaging model at first, where the scaling effect and Doppler frequency shift are jointly considered. Furthermore, two wideband CS imaging approaches are discussed in uniform scale-range space and velocity-range space, respectively. Besides, modified l1-norm minimization algorithms are proposed for the scene reconstruction in velocity-range space. Finally, numerical experiments are provided to demonstrate the effectiveness of the proposed model and the reconstruction algorithms.

关键词： compressed sensing sonar imaging wideband signal scaling effect modified l1 minimization

MIMO-SAR waveforms separation based on virtual polarization filter

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Science China(Information Sciences) 2015年第4期58卷 25-36页

作者： MENG CangZhen XU Jia xia xiang-gen LIU Feng LONG Teng MAO ErKe YANG Jian PENG YingNing Department of Electronic Engineering Tsinghua University Air force Early Warning Academy School of Information and Electronics Beijing Institute of Technology Department of Electrical and Computer Engineering University of Delaware

The unwanted coupling exists inevitably among multiple orthogonal waveforms in a same frequency area for multiple-input and multiple-output synthetic aperture radar(MIMO-SAR). In this paper, a new polarized MIMO-SAR model is established with two transmitting antennas and multiple receiving antennas at first. Then, a virtual polarization filter(VPF) is proposed to separate superposed returns caused by multiple transmitted waveforms based on detection on the polarized parameters via particle swarm optimizer(PSO).Compared with the conventional matched filter to separate the orthogonal waveforms, it is shown that the coupling noises can be significantly suppressed by the proposed VPF-based method and the orthogonality is not necessary among different transmitting waveforms. Finally, experimental data experiments are also provided to demonstrate the effectiveness of the proposed method.

关键词： multiple-input and multiple-output synthetic aperture radar(MIMO-SAR) orthogonal waveforms virtual polarization filter(VPF) part

The value of toxicological analysis in acute poisoning patients with uncertain exposure histories:a retrospective and descriptive study from an institute of poisoning

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World Journal of Emergency Medicine 2024年第2期15卷 98-104页

作者： Qifang Shi gen Ba Zhenyu xia Zhengsheng Mao Hao Sun Jinsong Zhang Institute of Poisoning Nanjing Medical UniversityNanjing 211100China Department of Emergency Medicine the First Affiliated Hospital of Nanjing Medical UniversityNanjing 210029China Department of Forensic Medicine Nanjing Medical UniversityNanjing 211166China The Key Laboratory of Modern Toxicology of Ministry of Education Nanjing Medical UniversityNanjing 211166China

BACKGROUND:In clinical practice,some patients might not be able or unwilling to provide a thorough history of medication and poison exposure.The aim of this study was to use toxicological analysis to examine the clinical characteristics of patients with acute poisoning whose exposure history was uncertain from a toxicological analysis perspective.METHODS:This was a retrospective and descriptive study from an institute of poisoning.Patient registration information and test reports spanning the period from April 1,2020 to March 31,2022,were obtained.Patients with uncertain exposure histories and who underwent toxicological analysis were included.Clinical manifestations and categories of toxics were analyzed.RESULTS:Among the 195 patients with positive toxicological analysis results,the main causes of uncertain exposure history was disturbance of consciousness(62.6%),unawareness(23.6%)and unwillingness or lack of cooperation(13.8%).The predominant clinical manifestations were disturbed consciousness(62.6%),followed by vomiting and nausea(14.4%)and liver function abnormalities(8.7%).A comparison of clinical manifestations between patients with positive and negative(n=99)toxicological analyses results revealed significantly different proportions of disturbances in consciousness(63%vs.21%),dizziness(1.5%vs.5.1%),multi-organ failure(1.5%vs.7.1%),and local pain(0 vs 4%).The main categories of substances involved were psychiatric medications(23.1%),sedatives(20.5%),insecticides(13.8%),and herbicides(12.8%).CONCLUSION:The clinical manifestations of acute poisoning in patients with an uncertain exposure history are diverse and nonspecific,and toxicological analysis plays a pivotal role in the diagnosis and differential diagnosis of such patients.

关键词： Acute poisoning Toxic exposure Toxicological analysis Clinical manifestation

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Understanding turbo codes: A signal processing study

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Journal of Information and Intelligence

Journal of Information and Intelligence 2024年第1期2卷 1-13页

作者： xiang-gen xia Department of Electrical and Computer Engineering University of DelawareDE 19716USA

In this paper,we study turbo codes from the digital signal processing point of view by defining turbo codes over the complex field.It is known that iterative decoding and interleaving between concatenated parallel codes are two key elements that make turbo codes perform significantly better than the conventional error control codes.This is analytically illustrated in this paper.We show that the decoded noise mean power in the iterative decoding decreases when the number of iterations increases,as long as the interleaving decorrelates the noise after each iterative decoding step.An analytic decreasing rate and the limit of the decoded noise mean power are given.The limit of the decoded noise mean power of the iterative decoding of a turbo code with two parallel codes with their rates less than 1/2 is one third of the noise power before the decoding,which can not be achieved by any non-turbo codes with the same rate.From this study,the role of designing a good interleaver can also be clearly seen.

关键词： Turbo codes Iterative decoding Modulated codes Interleaver design

Space/Air Covert Communications:Potentials,Scenarios,and Key Technologies

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China Communications 2024年第3期21卷 1-18页

作者： Mao Haobin Liu Yanming Zhu Lipeng Mao Tianqi xiao Zhenyu Zhang Rui Han Zhu xia xianggen School of Electronic and Information Engineering Beihang UniversityBeijing 100191China Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore School of Science and Engineering Shenzhen Research Institute of Big Datathe Chinese University of Hong KongShenzhenGuangdong 518172China Department of Electrical and Computer Engineering University of HoustonHoustonTX 77004USA Department of Computer Science and Engineering Kyung Hee UniversitySeoulSouth Korea446-701 Department of Electrical and Computer Engineering University of DelawareNewarkDE 19716USA

Space/air communications have been envisioned as an essential part of the next-generation mobile communication networks for providing highquality global connectivity. However, the inherent broadcasting nature of wireless propagation environment and the broad coverage pose severe threats to the protection of private data. Emerging covert communications provides a promising solution to achieve robust communication security. Aiming at facilitating the practical implementation of covert communications in space/air networks, we present a tutorial overview of its potentials, scenarios, and key technologies. Specifically, first, the commonly used covertness constraint model, covert performance metrics, and potential application scenarios are briefly introduced. Then, several efficient methods that introduce uncertainty into the covert system are thoroughly summarized, followed by several critical enabling technologies, including joint resource allocation and deployment/trajectory design, multi-antenna and beamforming techniques, reconfigurable intelligent surface(RIS), and artificial intelligence algorithms. Finally, we highlight some open issues for future investigation.

关键词： artificial intelligence(AI) sixth generation(6G) space-air-ground integrated networks(SAGINs) space/air covert communications

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两种修正的离散啁啾Fourier变换

中国科学（E辑） 2001年第6期31卷 514-525页

作者：平毅 xia xiang-gen 清华大学北京100084

提出了两种修正的离散啁啾Fourier变换, 并且研究了相应的滤波匹配特性包括变换长度参数的优化选取、及与模拟啁啾Fourier变换的关系. 与已有的离散啁啾Fourier变换相比,理论分析和模拟仿真证实了这两种修正的离散啁啾Fourier变换可以... 详细信息

提出了两种修正的离散啁啾Fourier变换, 并且研究了相应的滤波匹配特性包括变换长度参数的优化选取、及与模拟啁啾Fourier变换的关系. 与已有的离散啁啾Fourier变换相比,理论分析和模拟仿真证实了这两种修正的离散啁啾Fourier变换可以进一步提高被检测信号的啁啾分辨率.

关键词：离散啁啾Fourier变换信号检测频谱估计合成孔径雷达啁啾分辨率滤波分配雷达信号处理

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A projected Newton algorithm based on chemically allowed interval for chemical equilibrium computations

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Frontiers of Chemical Science and Engineering 2024年第3期18卷 25-37页

作者： Hongbin Lu Shaohui Tao xiaoyan Sun Li xia Shuguang xiang Institute of Process Systems Engineering College of Chemical EngineeringQingdao University of Science and TechnologyQingdao266042China

The chemical equilibrium equations utilized in reactive transport modeling are complex and nonlinear,and are typically solved using the Newton-Raphson method.Although this algorithm is known for its quadratic convergence near the solution,it is less effective far from the solution,especially for ill-conditioned problems.In such cases,the algorithm may fail to converge or require excessive iterations.To address these limitations,a projected Newton method is introduced to incorporate the concept of projection.This method constrains the Newton step by utilizing a chemically allowed interval that generates feasible descending iterations.Moreover,we utilize the positive continuous fraction method as a preconditioning technique,providing reliable initial values for solving the algorithms.The numerical results are compared with those derived using the regular Newton-Raphson method,the Newton-Raphson method based on chemically allowed interval updating rules,and the bounded variable least squares method in six different test cases.The numerical results highlight the robustness and efficacy of the proposed algorithm.

关键词： chemical equilibrium reactive transport modeling numerical methods projected Newton method

The innovative safe herbicide dienediamine saves paraquat

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Molecular Plant 2024年第1期17卷 11-12页

作者： Jin-Qiu xia Ping Xu Cheng-Bin xiang Division of Life Sciences and Medicine Division of Molecular&Cell BiophysicsHefei National Science Center for Physical Sciences at the MicroscaleMOE Key Laboratory for Membraneless Organelles and Cellular DynamicsUniversity of Science and Technology of ChinaThe Innovation Academy of Seed DesignChinese Academy of SciencesHefeiAnhui Province 230027China Shanghai Key Laboratory of Plant Functional genomics and Resources Shanghai Chenshan Botanical GardenShanghai Chenshan Plant Science Research CenterCAS Center for Excellence in Molecular Plant SciencesShanghai 201602China

Throughout the history of agriculture,the challenge of weed management has endured,necessitating significant investments to facilitate ideal crop growth and maximize yields.Strategies for weed control mainly involve manual and chemical methodologies.While manual weeding persists in certain regions,chemical herbicides notably represent the primary approach.

关键词： approach. manual chemical

Effectivity and safety of trifocal intraocular lenses and capsular tension rings implantation for cataract patients with axial high myopia

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International Journal of Ophthalmology(English edition) 2024年第3期17卷 499-508页

作者： Shan Hua Qiu-xia Xie Hu Wang Jing-xiang Zhong Dongguan Aier Eye Hospital Jinan UniversityDongguan 523106Guangdong ProvinceChina Department of Ophthalmology the First Affiliated Hospital of Jinan UniversityGuangzhou 510630Guangdong ProvinceChina Department of Ophthalmology the Sixth Affiliated Hospital of Jinan UniversityDongguan 523576Guangdong ProvinceChina

●AIM:To assess effectivity and safety of trifocal intraocular lenses(IOLs)and capsular tension rings in treating cataract patients with axial high myopia.●METHODS:A prospective nonrandomized controlled clinical trial was conducted.Totally 98 eyes(74 patients)who underwent femtosecond laser-assisted cataract surgery(FLACS)with trifocal IOLs were enrolled in the study and followed up for 2y after surgery:46 eyes(33 patients)with capsular tension ring implantation in the long axial lengths(AL)group(260.05).The dysfunctional lens index and total modulation transfer function(MTF)average height were similar between the two groups.The postoperative internal coma aberrations in the axial high myopia eyes were significantly higher than that in the normal AL group(P<0.05).The total satisfaction score in the long AL group(91.32±2.76)was slightly higher than that in the normal AL group(90.36±3.47),but there was no difference(P=0.136).A statistically negative correlation was found between corrected distance visual acuity(CDVA)and dysfunctional lens index(r=-0.382,P=0.009),and between CDVA and the total MTF average height(r=-0.374,P=0.01).But there was no significant correlation between CDVA and total satisfaction score(r=0.059,P=0.696).Postoperative complications mainly presented as posterior capsular opacity(PCO),retinal detachment and cystoid macular edema.There was no difference in the incidence of fundus disease(6.5%vs 3.8%,P=0.663)or PCO(1

关键词： trifocal intraocular lenses capsular tension ring axial high myopia cataract visual quality