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Cooperative Covert Communication in Multi-Antenna Broadcast Channels

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China Communications 2024年第6期21卷 246-260页

作者： Qiao Sen liu Guangjie ji Xiaopeng liu Weiwei School of Electrical and Information Engineering Nanjing University of Information Science and TechnologyNanjing 210044China School of Automation Nanjing University of Science and TechnologyNanjing 210094China

With the gradual popularization of 5G communications,the application of multi-antenna broadcasting technology has become ***,this study aims to investigate the wireless covert communication in the two-user cooperative multi-antenna broadcast *** focus on the issue that the deteriorated reliability and undetectability are mainly affected by the transmission *** tackle this issue,we design a scheme based on beamforming to increase the reliability and undetectability of wireless covert communication in the multi-antenna broadcast *** first modeled and analyzed the cooperative multi-antenna broadcasting system,and put forward the target *** we use the SCA(successive convex approximation)algorithm to transform the target problem into a series of convex *** the convex problems are solved and the covert channel capacity is *** order to verify the effectiveness of the scheme,we conducted simulation *** simulation results show that the proposed beamforming scheme can effectively improve the reliability and undetectability of covert communication in multi-antenna broadcast channels.

关键词： beamforming covert communication multi-antenna broadcast channels OFDM

Precise region semantics-assisted GAN for pose-guided person image generation

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CAAI Transactions on Intelligence Technology 2024年第3期9卷 665-678页

作者： ji.liu Zhenyu Weng Yuesheng Zhu Communication and Information Security Lab Shenzhen Graduate SchoolPeking UniversityShenzhenChina School of Electrical and Electronic Engineering Nanyang Technological UniversitySingaporeSingapore

Generating a realistic person's image from one source pose conditioned on another different target pose is a promising computer vision *** previous mainstream methods mainly focus on exploring the transformation relationship between the keypoint-based source pose and the target pose,but rarely investigate the region-based human semantic *** current methods that adopt the parsing map neither consider the precise local pose-semantic matching issues nor the correspondence between two different *** this study,a Region Semantics-Assisted Generative Adversarial Network(RSA-GAN)is proposed for the pose-guided person image gen-eration *** particular,a regional pose-guided semantic fusion module is first devel-oped to solve the imprecise match issue between the semantic parsing map from a certain source image and the corresponding keypoints in the source *** well align the style of the human in the source image with the target pose,a pose correspondence guided style injection module is designed to learn the correspondence between the source pose and the target *** addition,one gated depth-wise convolutional cross-attention based style integration module is proposed to distribute the well-aligned coarse style information together with the precisely matched pose-guided semantic information to-wards the target *** experimental results indicate that the proposed RSA-GAN achieves a 23%reduction in LPIPS compared to the method without using the seman-tic maps and a 6.9%reduction in FID for the method with semantic maps,respectively,and also shows higher realistic qualitative results.

关键词： deep learning image processing

Nacre-inspired MXene-based film for highly sensitive piezoresistive sensing over a broad sensing range

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Bio-Design and Manufacturing 2024年第4期7卷 463-475页

作者： Gaofeng Wang Lingxian Meng Xinyi ji Xuying liu jiajie Liang Shuiren liu School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China School of Materials Science and Engineering National Institute for Advanced MaterialsNankai UniversityTianjin 300350China

As the main component of wearable electronic equipment,flexible pressure sensors have attracted wide attention due to their excellent sensitivity and their promise with respect to applications in health monitoring,electronic skin,and human-computer ***,it remains a significant challenge to achieve epidermal sensing over a wide sensing range,with short response/recovery time and featuring seamless conformability to the skin *** is critical since the capture of minute electrophysiological signals is important for health care *** this paper,we report the preparation of a nacre-like MXene/sodium carboxymethyl cellulose(CMC)nanocomposite film with a“brick-and-mortar”interior structure using a vacuum-induced self-assembly *** synergistic behavior of the MXene“brick”and flexible CMC“mortar”contributes to attenuating interlamellar self-stacking and creates numerous variable conductive pathways on the sensing *** resulted in a high sensitivity over a broad pressure range(i.e.,0.03-22.37 kPa:162.13 kPa^(-1);22.37-135.71 kPa:127.88 kPa^(-1);135.71-286.49 kPa:100.58 kPa^(-1)).This sensor also has a low detection limit(0.85 Pa),short response/recovery time(8.58 ms/34.34 ms),and good stability(2000 cycles).Furthermore,we deployed pressure sensors to distinguish among tiny particles,various physiological signals of the human body,space arrays,robot motion monitoring,and other related applications to demonstrate their feasibility for a variety of health and motion monitoring use cases.

关键词： Flexible pressure sensor MXene Bioinspired Physiological signals Interlayer spacing

Kinetic scale magnetic holes in the terrestrial magnetosheath:A review

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Science China Earth Sciences 2024年第9期67卷 2739-2771页

作者： Quanqi SHI Shutao YAO Maria HAMRIN ji.liu Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China Department of Physics UmeåUniversityUmeå90746Sweden Department of Physics University of AlbertaEdmonton T6K 2P6Canada

Magnetic holes at the ion-to-electron kinetic scale(KSMHs)are one of the extremely small intermittent structures generated in turbulent magnetized *** recent years,the explorations of KSMHs have made substantial strides,driven by the ultra-high-precision observational data gathered from the Magnetospheric Multiscale(MMS)*** review paper summarizes the up-to-date characteristics of the KSMHs observed in Earth’s turbulent magnetosheath,as well as their potential impacts on space *** review starts by introducing the fundamental properties of the KSMHs,including observational features,particle behaviors,scales,geometries,and distributions in terrestrial *** have discovered that KSMHs display a quasi-circular electron vortex-like structure attributed to electron diamagnetic *** electrons exhibit noticeable non-gyrotropy and undergo *** occurrence rate of KSMH in the Earth’s magnetosheath is significantly greater than in the solar wind and magnetotail,suggesting the turbulent magnetosheath is a primary source ***,KSMHs have also been generated in turbulence simulations and successfully reproduced by the kinetic equilibrium ***,KSMHs have demonstrated their ability to accelerate electrons by a novel non-adiabatic electron acceleration mechanism,serve as an additional avenue for energy dissipation during magnetic reconnection,and generate diverse wave phenomena,including whistler waves,electrostatic solitary waves,and electron cyclotron waves in space *** results highlight the magnetic hole’s impact such as wave-particle interaction,energy cascade/dissipation,and particle acceleration/heating in space *** end this paper by summarizing these discoveries,discussing the generation mechanism,similar structures,and observations in the Earth’s magnetotail and solar wind,and presenting a future extension perspective in this active field.

关键词： Magnetic hole Magnetic dip/cavity Electron vortex Magnetosheath Turbulence Coherent structure Mirror mode Kinetic scale Electron acceleration Whistler

Influence of Incomplete Soil Plugs on Bearing Capacities of Bucket Foundations in Clay

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China Ocean Engineering 2024年第1期38卷 144-155页

作者： LI Hui-shan liu Run YANG Xu LIAN ji-jian State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300072China Institute of Marine Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China

Due to the uneven seabed and heaving of soil during pumping,incomplete soil plugs may occur during the installation of bucket foundations,and the impacts on the bearing capacities of bucket foundations need to be *** this paper,the contact ratio(the ratio of the top diameter of the soil plug to the diameter of the bucket)and the soil plug ratio(the ratio of the soil heave height to the skirt height)are defined to describe the shape and size of the incomplete soil ***,finite element models are established to investigate the bearing capacities of bucket foundations with incomplete soil plugs and the influences of the contact ratios,and the soil plug ratios on the bearing capacities are *** results show that the vertical bearing capacity of bucket foundations in homogeneous soil continuously improves with the increase of the contact ***,in normally consolidated soil,the vertical bearing capacity barely changes when the contact ratio is smaller than 0.75,while the bearing capacity suddenly increases when the contact ratio increases to 1 due to the change of failure *** contact ratio hardly affects the horizontal bearing capacity of bucket ***,the moment bearing capacity improves with the increase of the contact ratio for small aspect ratios,but hardly varies with increasing contact ratio for aspect ratios larger than ***,the reduction coefficient method is proposed based on this analysis to calculate the bearing capacities of bucket foundations considering the influence of incomplete soil *** comparison results show that the proposed reduction coefficient method can be used to evaluate the influences of incomplete soil plug on the bearing capacities of bucket foundations.

关键词： bucket foundation incomplete soil plug uniaxial bearing capacity contact ratio soil plug ratio

Defects in the grain interiors of 3 mol%yttria-stabilized tetragonal zirconia polycrystal ceramics with 0.25 wt%alumina

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Journal of Advanced Ceramics 2024年第4期13卷 469-477页

作者： Yan Xiong Lian Luo Yao Cheng Zhi liu Qi liu Weimin Wang Wei ji School of Materials&Chemical Engineering Hubei Province Key Laboratory of Green Materials for Light IndustryHubei University of TechnologyWuhan 430068China Fujian Institute of Research on the Structure of Mater Chinese Academy of SciencesFuzhou 350002China jiangxi Provincial Engineering Research Center for Multifunction Zirconia Materials Jiangxi Size Materials Co.Ltd.Jiujiang 332500China State Key Laboratory of Advance Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

The presence of high-density defects is rarely observed in bulk 3 mol%yttria-stabilized tetragonal zirconia polycrystal(3Y-TZP)ceramics obtained through conventional pressureless *** the present work,fine-grained dense 147 nm 3Y-TZP ceramics were prepared by pressureless sintering of commercial 0.25 wt%alumina-doped zirconia powders at 1300℃.A novel discovery was reported in which large amounts of defects were present in the grain interiors of the *** phenomenon was further examined using three types of powder samples,and the reasons for defect formation were investigated by microstructural characterization using high-resolution transmission electron microscopy(HRTEM)analysis and Rietveld *** results confirmed the essential dependence of the defect formation on the alumina *** authors attributed the defect formation to the significant difference in ionic radii of the solvent and solute during the dissolution of alumina into the zirconia *** sintering kinetics were proposed to be enhanced by the presence of substantial defects,which consequently favored the low-temperature sintering of the alumina-doped zirconia ceramics.

关键词： 3 mol%yttria-stabilized tetragonal zirconia polycrystal(3Y-TzP)ceramics alumina addition microstructure defect

A polymyxin B loaded hypoxia-responsive liposome with improved biosafety for efficient eradication of bacterial biofilms

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Nano Research 2024年第9期17卷 8325-8336页

作者： Fang liu Lingyun Zou Yongcheng Chen Zuolong liu Yue Huang Qiao jin jian ji MOE Key Laboratory of Macromolecule Synthesis and Functionalization of Ministry of Education Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China State Key Laboratory of Transvascular Implantation Devices The Second Affiliated Hospital Zhejiang University School of MedicineHangzhou 310009China

Biofilm-associated bacterial infection brings serious threats to global public health owing to serious antibiotic *** is urgently needed to develop innovative strategies to combat biofilm-associated bacterial *** stand out as the last line of defense against Gram-negative ***,serious nephrotoxicity of polymyxins severely limits their clinical ***,a hypoxia-responsive liposome is designed as the nanocarrier of polymyxin B(PMB)to combat biofilms developed by Gram-negative bacteria.A metronidazole modified lipid(hypoxia-responsive lipid(HRLipid))is synthesized to fabricate hypoxia-responsive liposomes(HRLip).PMB loaded hypoxia-responsive liposomes(HRL-PMB)is then prepared to mitigate the nephrotoxicity of PMB while preserving its excellent bactericidal ***-PMB shows very low hemolysis and cytotoxicity due to liposomal encapsulation of *** can be readily released from HRL-PMB in response to hypoxic biofilm microenvironment,exerting its bactericidal activity to realize biofilm *** excellent in vivo antibiofilm ability of HRL-PMB is confirmed by a Pseudomonas aeruginosa infected zebrafish model and a *** pneumonia infection ***,HRL-PMB can greatly reduce the nephrotoxicity of PMB after intravenous *** hypoxia-sensitive liposomes held great promise to improve the biosafety of highly toxic antibiotics while preserving their intrinsic bactericidal ability,which may provide an innovative strategy for combating biofilm-associated infections.

关键词： bacterial biofilm hypoxia liposome polymyxin B nephrotoxicity

Human activity over natural inputs determines the bacterial community in an ice core from the Muztag ata glacier

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Science China Earth Sciences 2024年第5期67卷 1489-1499页

作者： Yongqin liu Nianzhi jiAO Mukan ji Keshao liu Baiqing XU Bixi GUO Tandong YAO State Key Laboratory of Tibetan Plateau Earth System Resources and Environment(TPESRE)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Center for Pan-third Pole Environment Lanzhou UniversityLanzhou 730013China University of Chinese Academy of Sciences Beijing 100101China State Key Laboratory for Marine Environmental Science Xiamen UniversityXiamen 361102China

Ice core provides a valuable vertical timeline of past climates and anthropogenic *** proxies have been widely used in these studies,but there are few biological indicators *** address this gap,we investigated the bacterial community from a 74 m ice core of Muztag ata glacier on the Tibetan Plateau to link biological indicators with past climate and anthropogenic *** analyzing the portion of the ice core with environmental proxies available(corresponding to 1907 to 1991),we observed an increase in bacterial richness throughout the ice core,which was associated with higher NH_(4)^(+),an indicator of agricultural *** bacterial community was jointly determined by human activity,natural input,and air temperature,with a strong human influence after the ***,the relative abundance of animal gut-associated bacteria,including Aerococcaceae,Nocardiaceae,Muribaculaceae,and Lachnospiraceae,was associated with livestock number changes in the Central Asian *** with other bacterial lineages,they jointly explained 59.8%of the livestock number *** study provides quantitative evidence of the associations between bacterial indicators and past climate and human activities,highlighting the potential of using bacterial proxies for ice core studies.

关键词： Ice core of Muztag ata glacier Climate change and anthropogenic activity Biological indicator Gut-associated bacteria livestock number in the Central Asian region

The New Methods for Characterization of Molecular Weight of Supramolecular Polymers

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Chinese Journal of Polymer Science 2024年第10期42卷 1403-1413,I0006页

作者： Hui liu Rui Hu Zi-Qing Hu Xiao-Fan ji Key Laboratory of Materials Chemistry for Energy Conversion and Storage Ministry of EducationHubei Key Laboratory of Materials Chemistry and Service FailureHubei Engineering Research Center for Biomaterials and Medical Protective MaterialsSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan430074China

Supramolecular polymers,as a type of dynamic polymers,are subordinate to the interdisciplinary field of polymer chemistry and supramolecular chemistry,whose development has greatly promoted the prosperity of new ***,molecular weight is one of the most important parameters of supramolecular polymers,which affects the physical/chemical properties and processing applications of *** new methods for characterizing the molecular weight of supramolecular polymers is crucial for advancing the development of supramolecular *** this review,we elaborate and summarize three strategies for characterizing the molecular weight of supramolecular polymers that recently reported by our research group according to the characteristics of supramolecular polymers,including(1)the molecular weight distinction corresponding to variable fluorescence colors,(2)matching different molecular weights with different fluorescence lifetime,(3)transforming supramolecular polymers into mechanically interlocked polymers or covalent ***,we also discuss the limitations of current methods for characterizing supramolecular *** hope that this review can promote the development of supramolecular polymers and significantly inspire to exploit new methods to characterizing molecular weight of supramolecular polymers.

关键词： Supramolecular polymers Molecular weight Self-assembly Mechanically interlocked polymers Dynamic polymers