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Distortion-aware beamforming design for multi-beam satellite communications with nonlinear power amplifiers

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Science China(Information Sciences) 2024年第6期67卷 359-369页

作者： Xiang XIAO li you Kezhi WANG Xiqi GAO National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratories Department of Computer Science Brunel University London

Hardware components can cause different impairments, including power amplifier(PA) nonlinearities, which inevitably impact the system performance of satellite communications(SATCOM). In this work, we consider a multi-beam SATCOM downlink system and investigate the distortion-aware beamforming scheme with the characteristics of PA non-linearities. Notably, we aim to maximize the resource efficiency(RE), defined as the weighted sum of energy efficiency(EE) with spectral efficiency(SE), to obtain a flexible EE-SE tradeoff while accounting for the characteristics of PA distortion and the total power *** that the optimization objective is a sum of ratios and the high non-convexity involved in constraints,we propose an efficient approach that exploits the quadratic transformation, the Lagrange multiplier method,and the gradient ascent approach to handle this issue. Simulation results demonstrate the effectiveness of the distortion-aware beamforming approach in achieving the EE-SE tradeoff and exhibit a substantial RE performance gain over the conventional approach with ideal linear PAs assumed at the satellite transmitters.

关键词： multi-beam satellite communications nonlinear power amplifier energy and spectral efficiency tradeoff resource efficiency robust beamforming

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OFDMA-Based Unsourced Random Access in LEO Satellite Internet of Things

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China Communications 2024年第1期21卷 13-23页

作者： Jiaqi Fang Gangle Sun Wenjin Wang li you Rui Ding National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Purple Mountain Laboratories Nanjing 211100China Institute of Telecommunication Satellite CASTBeijing 100094China

This paper investigates the low earth orbit(LEO)satellite-enabled coded compressed sensing(CCS)unsourced random access(URA)in orthogonal frequency division multiple access(OFDMA)framework,where a massive uniform planar array(UPA)is equipped on the *** LEO satellite communications,unavoidable timing and frequency offsets cause phase shifts in the transmitted signals,substantially diminishing the decoding performance of current terrestrial CCS URA *** cope with this issue,we expand the inner codebook with predefined timing and frequency offsets and formulate the inner decoding as a tractable compressed sensing(CS)***,we leverage the inherent sparsity of the UPA-equipped LEO satellite angular domain channels,thereby enabling the outer decoder to support more active ***,the outputs of the outer decoder are used to reduce the search space of the inner decoder,which cuts down the computational complexity and accelerates the convergence of the inner *** results verify the effectiveness of the proposed scheme.

关键词： LEO OFDMA satellite unsourced random access UPA

Effect of TiO_(2) addition on microstructures and properties of Mgo-Cao refractory aggregates

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Journal of Iron and Steel Research(International) 2024年第6期31卷 1547-1554页

作者： Shuai Zhang Jing-ran Wang Yuan-gao li Feng-you li Wen Yan Hui-ying Shi The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Joint International Research Laboratory of Refractories and Metallurgy Wuhan 430081HubeiChina Shanxi Luweibao Taigang Refractory Co. Ltd.Taiyuan 030003ShanxiChina

MgO-CaO(40 wt.%CaO)refractory aggregates were prepared using the calcined dolomite and light-burned magnesia fine powder as raw materials and TiO_(2) as *** effect of TiO_(2) on their phase composition,microstructures and properties was investigated by X-ray diffraction and scanning electron *** properties such as bulk density,apparent porosity,relative aggregate tube strength and hydration resistance were also *** results showed that the CaTiO_(3) generated by the reaction between CaO and TiO_(2) was distributed around the CaO grain boundaries and intermittently distributed with MgO,which formed an isolation layer around CaO and greatly improved the hydration ***,the introduction of TiO_(2) promoted sintering and increased the grain size,further improving the strengths and hydration resistance of the *** addition,the most significant enhancement in the hydration resistance and strengths of the samples was achieved when 1.0-2.0 wt.%TiO_(2) was *** this case,the relative strength of aggregate increased from 33.3% to 37.3%-43.1%,and the mass gain after the hydration test decreased from 3.13% to 1.26%-1.45%.

关键词： MgO-CaO refractory aggregate TiO_(2)addition Phase composition Microstructure Hydration resistance

Pre-MASLD:Should it be defined separately?

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Hepatobiliary & Pancreatic Diseases International 2024年第1期23卷 1-3页

作者： Hang-Kai Huang you-Ming li Cheng-Fu Xu Department of Gastroenterology Zhejiang Provincial Clinical Research Center for Digestive Diseasesthe First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China

Nonalcoholic fatty liver disease(NAFLD)is one of the most common chronic liver diseases,yet it has not received sufficient attention[1].Over the past two decades,the overall global prevalence of NAFLD has risen from 25%to 37%[2].The disease burden of NAFLD is fueled by the epidemic of obesity and diabetes[3].It is estimated that more than half of patients with diabetes have NAFLD.

关键词： NAFLD liver diseases

AstroPose:Astronaut pose estimation using a monocular camera during extravehicular activities

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Science China(Technological Sciences) 2024年第6期67卷 1933-1945页

作者： liU ZiBin li you WANG ChunHui liU liang GUAN BangLei SHANG Yang YU QiFeng College of Aerospace Science and Engineering National University of Defense TechnologyChangsha410073China Key Laboratory of Human Factors Engineering China Astronaut Research and Training CenterBeijing100094China

With the completion of the Chinese space station,an increasing number of extravehicular activities will be executed by astronauts,which is regarded as one of the most dangerous activities in human space *** guarantee the safety of astronauts and the successful accomplishment of missions,it is vital to determine the pose of astronauts during extravehicular *** article presents a monocular vision-based pose estimation method of astronauts during extravehicular activities,making full use of the available observation ***,the camera is calibrated using objects of known structures,such as the spacesuit backpack or the circular handrail outside the space ***,the pose estimation is performed utilizing the feature points on the *** proposed methods are validated both on synthetic and semi-physical simulation experiments,demonstrating the high precision of the camera calibration and pose *** further evaluate the performance of the methods in real-world scenarios,we utilize image sequences of Shenzhou-13 astronauts during extravehicular *** experiments validate that camera calibration and pose estimation can be accomplished solely with the existing observation resources,without requiring additional complicated *** motion parameters of astronauts lay the technological foundation for subsequent applications such as mechanical analysis,task planning,and ground training of astronauts.

关键词： monocular camera astronaut pose estimation camera calibration

Activatable fluorescent probes for imaging and diagnosis of rheumatoid arthritis

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Military Medical Research 2024年第2期11卷 287-307页

作者： Pan Luo Fu-Qiang Gao Wei Sun Jun-you li Cheng Wang Qing-Yu Zhang Zhi-Zhuo li Peng Xu Department of Joint Surgery Honghui HospitalXi'an Jiaotong UniversityXi'an 710054China Department of Orthopedics China-Japan Friendship HospitalBeijing 100029China Department of Orthopaedic Surgery of the Perelman School of Medicine University of PennsylvaniaPhiladelphiaPA 19104USA School of Mechanical Engineering Sungkyunkwan UniversitySuwon 16419South Korea Department of Orthopaedic Surgery Peking University Third HospitalPeking UniversityBeijing 100191China Department of Orthopedics Shandong Provincial Hospital Affiliated to Shandong First Medical UniversityJinan 250021China State Key Laboratory of Pharmaceutical Biotechnology Division of Sports Medicine and Adult Reconstructive SurgeryDepartment of Orthopedic SurgeryNanjing Drum Tower Hospitalthe Affiliated Hospital of Nanjing University Medical SchoolNanjing 210008China

Rheumatoid arthritis(RA)is a systemic autoimmune disease that is primarily manifested as synovitis and polyarticular opacity and typically leads to serious joint damage and irreversible disability,thus adversely affecting locomotion ability and life ***,good prognosis heavily relies on the early diagnosis and effective therapeutic monitoring of *** fluorescent probes play vital roles in the detection and imaging of biomarkers for disease diagnosis and in vivo ***,we review the fluorescent probes developed for the detection and imaging of RA biomarkers,namely reactive oxygen/nitrogen species(hypochlorous acid,peroxynitrite,hydroxyl radical,nitroxyl),pH,and cysteine,and address the related challenges and prospects to inspire the design of novel fluorescent probes and the improvement of their performance in RA studies.

关键词： Rheumatoid arthritis Fluorescent probe Imaging Diagnosis Biomarker

Automatic detection of breast lesions in automated 3D breast ultrasound with cross-organ transfer learning

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虚拟现实与智能硬件（中英文） 2024年第3期6卷 239-251页

作者： lingyun BAO Zhengrui HUANG Zehui liN Yue SUN Hui CHEN you li Zhang li Xiaochen YUAN lin XU Tao TAN Affiliated Hangzhou First People's Hospital School of MedicineWestlake UniversityHangzhou 330100China Faculty of Applied Sciences Macao Polytechnic UniversityMacao 999078China Pathology Department Changsha First HospitalChangsha 410073China Radiology Department Changsha First HospitalChangsha 410073China College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China Hunan Provincial Key Laboratory of Image Measurement and Vision Navigation Changsha 410073China School of Information Science and Technology Shanghaitech UniversityShanghai 201210China

Background Deep convolutional neural networks have garnered considerable attention in numerous machine learning applications,particularly in visual recognition tasks such as image and video *** is a growing interest in applying this technology to diverse applications in medical image *** three dimensional Breast Ultrasound is a vital tool for detecting breast cancer,and computer-assisted diagnosis software,developed based on deep learning,can effectively assist radiologists in ***,the network model is prone to overfitting during training,owing to challenges such as insufficient training *** study attempts to solve the problem caused by small datasets and improve model detection *** We propose a breast cancer detection framework based on deep learning(a transfer learning method based on cross-organ cancer detection)and a contrastive learning method based on breast imaging reporting and data systems(BI-RADS).Results When using cross organ transfer learning and BIRADS based contrastive learning,the average sensitivity of the model increased by a maximum of 16.05%.Conclusion Our experiments have demonstrated that the parameters and experiences of cross-organ cancer detection can be mutually referenced,and contrastive learning method based on BI-RADS can improve the detection performance of the model.

关键词： Breast ultrasound Automated 3D breast ultrasound Breast cancers Deep learning Transfer learning Convolutional neural networks Computer-aided diagnosis Cross organ learning

A N-CoSe/CoSe2-C@Cu hierarchical architecture as a current collector-integrated anode for potassium-ion batteries

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Rare Metals 2024年第8期43卷 3702-3712页

作者： Zi-Jie Mu Yan-Jun Gao Wen-Shuai Dong Zong-you li Qing-Yi Song Han-Jiao Huang li-Dong Xing Jian-Guo Zhang Wei Wang Qi-Yao Yu State Key Laboratory of Explosion Science and Technology School of Mechatronical EngineeringBeijing Institute of Technology School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

The highly reversible insertion/extraction of large-radius K+into electrode materials remains a tough goal,especially for con version-type ***,we design a current collector-integrated electrode（N-CoSe/CoSe2-C@Cu） as an advanced anode for potassium-ion battery（PIBs）.The conductive CoSe/CoSe2heterojunction with rich Se vacancy defects,conductive sp2N-doped carbon layer,and the elastic copper foil matrix can greatly accelerate the electron transfer and enhance the structural ***,the well-designed N-CoSe/CoSe2-C@Cu current collector-integrated electrode displays enhanced potassium storage performance with regard to a high capacity(325.1 mAh·g-1at 0.1 A·g-1after 200cycles),an exceptional rate capability(223.5 mAh·g-1at2000 mA·g-1),and an extraordinary long-term cycle stability(a capacity fading of only 0.019% per cycle over1200 cycles at 2000 mA·g-1).Impressively,ex situ scanning electron microscopy（SEM） characterizations prove that the elastic structure of copper foil is merged into the cleverly designed N-CoSe/CoSe2-C@Cu heterostructure,which buffers the deformation of structure and volume and greatly promotes the cycle life during the potassium/depotassium process.

关键词： Potassium-ion battery Integrated collector electrode CoSe CoSe 2 Heterojunction Copper foil matrix N-doped carbon

Insights of carbon reduction practices from Winter Olympics 2022

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Science Bulletin 2024年第13期69卷 2034-2037页

作者： Xiaoyong liao Shuai Zhong Jie Huang Zhu liu Ayman Elshkaki you li Lei Shen Yingli He li An Yidong Zhu Wenhao Sun Tao liang Jiaoe Wang Jinwei Dong Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Key Laboratory for Resources Use and Environmental Remediation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Key Laboratory of Regional Sustainable Development Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Department of Earth System Science Tsinghua UniversityBeijing 100084China

Concerns about the carbon emissions of mega-events revolve,mainly due to the impactful demonstration effects they ***,accurate monitoring of these emissions is crucial during such events[1].The Olympic and Paralympic Winter Games Beijing 2022(hereinafter“Winter Olympics 2022”)are recognized as the first Games to pay close attention to a wide range of emissions associated with all stages of the *** of emerging carbon reduction technologies,such as low-carbon materials and technologies,have shown promising effects on efforts to achieve carbon neutrality[2].The impacts of individual measures,such as Olympic infrastructure construction.

关键词： Winter emissions carbon