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Beamforming design for covert broadcast communication with hidden adversary

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Science China(Information Sciences) 2024年第6期67卷 384-398页

作者： Weiyu CHEN Haiyang DING Shilian WANG Junshan LUO Fengkui GONG college of Electronic Science and technology National University of Defense Technology college of Information and communication National University of Defense Technology State Key Laboratory of Integrated Service Networks Xidian University

This paper explores covert broadcast communication in a challenging situation in which the transmitter, Alice, faces uncertainty regarding the position of the passive adversary, Willie. In this situation,controlling the signal exposure becomes difficult. Specifically, this paper focuses on the cases where Alice can delimit the suspicious areas where Willie may be located. The suspicious areas can have arbitrary number and shapes. Under the Rician fading model, the analytical expression of Willie's detection performance is derived. Then, the transmit power, the beamforming direction, and the number of channel uses are jointly designed to minimize the optimal Willie's detection performance among all the possible positions of Willie, on the premise of satisfying receivers' quality-of-service requirements. To tackle the formulated knotty problem with an infinite number of irregular and discontinuous Willie's possible positions, the continuous nature of the antenna pattern is exploited to convert the original problem into the one with a finite number of possible positions, by sampling the suspicious areas. Then, different algorithms are developed to address the resultant non-convex optimization problem for single-antenna Willie and multi-antenna Willie, respectively. Numerical results demonstrate significant performance gains of the proposed scheme over the widely-adopted maximum ratio transmission scheme, which indicates that simply adjusting the main lobe towards the receiver is indeed far away from optimum and shows the importance of leveraging Alice's limited knowledge of Willie's position.

关键词： low-probability-of-detection communication multiple antennas covertness performance uncertain position parameters optimization

Programmable and reconfigurable humidity-driven actuators made with MXene(Ti_(3)C_(2)T_(x))-cellulose nanofiber composites for biomimetic applications

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Nano Research 2024年第7期17卷 6619-6629页

作者： Shaofeng Zeng Yuanji Ye Peidi Zhou Shimin Yi Qiaohang Guo Huamin Chen Guozhen Shen Mingcen Weng School of Mechanical and Automotive Engineering Fujian University of TechnologyFuzhou 350118China School of Materials Science and Engineering Fujian Provincial Key Laboratory of Advanced Materials Processing and ApplicationKey Laboratory of Polymer Materials and Products of Universities in FujianFujian University of TechnologyFuzhou 350118China Institute of Smart Marine and Engineering Fujian University of TechnologyFuzhou 350118China fujian Key Laboratory of Functional Marine Sensing Materials College of Materials and Chemical EngineeringMinjiang UniversityFuzhou 350108China School of Integrated Circuits and Electronics Beijing Institute of TechnologyBeijing 100081China

Smart actuators have a wide range of applications in bionics and energy *** ability to reconfigure shape is essential for soft actuators to achieve various shapes and deformations,which is a crucial feature for next-generation ***,it is still an enormous challenge to establish a straightforward approach to creating programmable and reconfigurable ***-cellulose nanofiber composite film(MCCF)with a brick-and-mortar hierarchical structure was produced through a vacuum filtration *** demonstrates impressive mechanical properties such as a tensile stress of 68 MPa and a Young’s modulus of 4.65 ***,the MCCF highlights its potential for water-assisted shaping/welding due to the abundance of hydrogen bonds between MXene and cellulose *** also showcases capabilities as a humiditydriven actuator with a rapid response rate of 550°·s^(−1).Using the methods of water-assisted shaping/welding,several bionic actuators(such as flower,butterfly,and muscle)based on MCCF were designed,highlighting their versatility in applications of smart *** research showcases the impressive capabilities of MXene-based actuators and offers beneficial insights for the advancement of future intelligent materials.

关键词： MXene cellulose nanofibers programmable actuators humidity-driven

Spatiotemporal Evolution of Urban Heat Islands and Optimization of Spatial Network Construction in the Central Urban Area of Fuzhou City, China

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Chinese Geographical Science 2024年第5期34卷 917-930页

作者： ZHAO Qiuyue YU Kunyong GENG Jianwei LIN Jiqing AI Jingwen LIU Jian college of Landscape Architecture Fujian Agriculture and Forestry UniversityFuzhou 350002China University Key Lab for Geomatics technology and Optimize Resources Utilization in fujian Province Fujian Agriculture and Forestry UniversityFuzhou 350002China

Although accelerated urbanization has led to economic prosperity,it has also resulted in urban heat island ***,identifying methods of using limited urban spaces to alleviate heat islands has become an urgent *** this study,we assessed the spatiotemporal evolution of urban heat islands within the central urban area of Fuzhou City,China from 2010 to *** assessment was based on a morphological spatial pattern analysis(MSPA)model and an urban thermal environment spatial network constructed us-ing the minimum cumulative resistance(MCR)*** measures for the spatial network were proposed to provide a theor-etical basis for alleviating urban heat *** results show that the heat island area within the study area gradually increased while that of urban cold island area gradually *** core area was the largest of the urban heat island patch landscape elements with a significant impact on other landscape elements,and represented an important factor underlying urban heat island network *** thermal environment network revealed a total of 197 thermal environment corridors and 93 heat island *** locations were then optimized according to the current land use,which maximized the potential of 1599.83 *** based on current land use led to an increase in climate resilience,with effective measures showing reduction in thermal environment spatial network structure and function,contributing to the mitigation of urban heat *** findings support the use of current land use patterns during urban heat island mitigation measure planning,thus providing an important reference basis for alleviating urban heat island effects.

关键词： urban heat island spatiotemporal analysis circuit theory post optimization evaluation climate mitigation Fuzhou City,China

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Magnetic Field Controllable Photocurrent Properties in BiFe_(0.9)Ni_(0.1)O_(3)/La_(0.7)Sr_(0.3)MnO_(3) Laminate Thin Film

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Energy & Environmental Materials 2024年第2期7卷 381-388页

作者： Guanzhong Huo Ke Wang Qingying Ye Shuiyuan Chen Chao Su Yuxiang Zhang Guilin Chen Zhigao Huang fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials College of Physics and EnergyFujian Normal UniversityFuzhou 350117China fujian Provincial Engineering technology Research Center of Solar Energy Conversion and Energy Storage Fuzhou 350117China

This paper reports a multifunctional magnetic-photoelectric laminate device based on the integration of spintronic material(La_(0.7)Sr_(0.3)MnO_(3))and multiferroic(Ni-doped BiFeO_(3)),in which the repeatable modulation effect on the photoelectric properties were achieved by applying external magnetic *** obviously,photocurrent density(J)of the laminate was largely enhanced,the change rate of J up to 287.6%is *** sensing function effect should be attributed to the low-field magnetoresistance effect in perovskite manganite and the scattering of spin photoelectron in multiferroic *** laminate perfectly combines the functions of sensor and controller,which can not only reflect the intensity of environmental magnetic field,but also modulate the photoelectric conversion *** work provides an alternative and facile way to realize multi-degree-of-freedom control for photoelectric conversion performances and lastly miniaturize multifunction device.

关键词： bismuth ferrite low-field magnetoresistance effect magnetic field modulation perovskite manganite photocurrent

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An Optimal Node Localization in WSN Based on Siege Whale Optimization Algorithm

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2201-2237页

作者： Thi-Kien Dao Trong-The Nguyen fujian Provincial Key Laboratory of Big Data Mining and Applications Fujian University of TechnologyFuzhou350118China Multimedia communication Lab University of Information TechnologyHo Chi Minh CityVietnam

Localization or positioning scheme in Wireless sensor networks (WSNs) is one of the most challenging andfundamental operations in various monitoring or tracking applications because the network deploys a large areaand allocates the acquired location information to unknown devices. The metaheuristic approach is one of themost advantageous ways to deal with this challenging issue and overcome the disadvantages of the traditionalmethods that often suffer from computational time problems and small network deployment scale. This studyproposes an enhanced whale optimization algorithm that is an advanced metaheuristic algorithm based on thesiege mechanism (SWOA) for node localization inWSN. The objective function is modeled while communicatingon localized nodes, considering variables like delay, path loss, energy, and received signal strength. The localizationapproach also assigns the discovered location data to unidentified devices with the modeled objective functionby applying the SWOA algorithm. The experimental analysis is carried out to demonstrate the efficiency of thedesigned localization scheme in terms of various metrics, e.g., localization errors rate, converges rate, and executedtime. Compared experimental-result shows that theSWOA offers the applicability of the developed model forWSNto perform the localization scheme with excellent quality. Significantly, the error and convergence values achievedby the SWOA are less location error, faster in convergence and executed time than the others compared to at least areduced 1.5% to 4.7% error rate, and quicker by at least 4%and 2% in convergence and executed time, respectivelyfor the experimental scenarios.

关键词： Node localization whale optimization algorithm wireless sensor networks siege whale optimization algorithm optimization

Biophotoelectrochemistry for the treatment of emerging contaminants

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Science China Technological Sciences 2024年第10期67卷 3051-3066页

作者： HU Jing CHEN Man GU WenZhi DENG WenEr HONG MingQiu HU AnDong YE Jie ZHOU ShunGui fujian Provincial Key Laboratory of Soil Environmental Health and Regulation College of Resources and EnvironmentFujian Agriculture and Forestry University

Emerging contaminants(ECs) of significant concern are widely distributed throughout the environment due to various industrial practices and human activities. Given the alarming ecological threats and potential risks that ECs pose to human health and aquatic life, even at trace concentrations, it is imperative to develop innovative technologies to effectively address these challenges. The biophotoelectrochemistry(BPEC) system, which integrates microbial cells with photosensitizers for solar-tochemical conversion, holds great potential as an efficient strategy for the removal of ECs. In this review, we provide new insights into the BPEC system for the ECs treatment by systematically summarizing the classification, sources, and environmental occurrence of ECs. Additionally, we explore the research progress and degradation mechanisms in ECs removal with ***, the current challenges and future perspectives for the applications of the BPEC system in the ECs treatment are *** review aims to promote the development of BPEC technology for ECs treatment, offering a promising prospect for environmental remediation, circular economy, and clean-energy production.

关键词： emerging contaminants biophotoelectrochemistry photocatalysis biodegradation

Fabrication of Silane and Desulfurization Ash Composite Modified Polyurethane and Its Interfacial Binding Mechanism

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Journal of Wuhan University of technology(Materials Science) 2024年第2期39卷 288-297页

作者：吴旺华 CHEN Shuichang YE Haodong 李世迁 LIN Yuanzhi 陈庆华 XIAO Liren college of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350117China college of Materials and Package Engineering Fujian Provincial Key Lab of Coastal Basin EnvironmentFujian Polytechnic Normal UniversityFuqing 350300China college of Agriculture Guangxi UniversityGuangxi 530004China

Polyurethane/desulfurization ash(PU/DA)composites were synthesized using"one-pot method",with the incorporation of a silane coupling agent(KH550)as a"molecular bridge"to facilitate the integration of DA as hard segments into the PU molecular *** effects of DA content(φ)on the mechanical properties,thermal stability,and hydrophobicity of PU,both before and after the addition of KH550,were thoroughly *** results of microscopic mechanism analysis confirmed that KH550 chemically modified the surface of DA,facilitating its incorporation into the polyurethane molecular chain,thereby significantly enhancing the compatibility and dispersion of DA within the PU *** the mass fraction of modified DA(MDA)reached 12%,the mechanical properties,thermal stability,and hydrophobicity of the composites were substantially improved,with the tensile strength reaching 14.9 MPa,and the contact angle measuring 100.6°.

关键词： polyurethane silane coupling agent desulfurization ash modification mechanical property hydrophobicity thermal stability

Optically levitated micro gyroscopes with an MHz rotational vaterite rotor

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Microsystems & Nanoengineering 2024年第3期10卷 219-227页

作者： Kai Zeng Xiangming Xu Yulie Wu Xuezhong Wu Dingbang Xiao college of Intelligence Science and technology National University of Defense TechnologyChangsha 410073China college of Information and communication National University of Defense TechnologyWuhan 430000China Key Laboratory of Satellite Navigation technology National University of Defense TechnologyChangsha 410073China

The field of levitated optomechanics has experienced significant advancements in manipulating the translational and rotational dynamics of optically levitated particles and exploring their sensing *** concept of using optically levitated particles as gyroscopes to measure angular motion has long been explored but has not yet been proven either theoretically or *** this study,we present the first rotor gyroscope based on optically levitated high-speed rotating *** gyroscope is composed of a micrometer-size ellipsoidal vaterite particle that is driven to rotate at MHz frequencies in a vacuum *** an external angular velocity is input,the optical axis deviates from its initial position,resulting in changes in the frequency and amplitude of the rotational *** analyzing these changes,the angular velocity of the input can be accurately detected,making it the smallest rotor gyroscope in the *** angular rate bias instability of the gyroscope is measured to be 0.08°/s and can be further improved to as low as 10^(−9)°/h theoretically by cooling the motion and increasing the angular moment of the levitated *** work opens a new application paradigm for levitated optomechanical systems and may pave the way for the development of quantum rotor gyroscopes.

关键词： particles rotational angular

Intelligent reflecting surfaces-assisted millimeter wave communication:Channel estimation based on deep learning

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The Journal of China Universities of Posts and Telecommunications 2024年第1期31卷 49-56页

作者： Kang Xiaofei Wang Tian Liang Xian college of communication and Information Engineering Xi'an University of Science and TechnologyXi'an 710600China

In response to the challenge posed by the complexity of the system and the difficulty in obtaining accurate channel state information(CSI)for millimeter wave communication assisted by intelligent reflecting surfaces(IRS),we propose a deep learning-based channel estimation *** proposed scheme employs a hybrid active/passive IRS architecture,wherein the least square(LS)algorithm is initially utilized to acquire the channel estimate from the active ***,this estimation is interpolated to obtain a preliminary channel estimation and ultimately refined into an accurate estimate of the channel using the channel super-resolution convolutional neural network(Chan-SRCNN)deep learning *** simulation results demonstrate that the proposed scheme surpasses LS,orthogonal matching pursuit(OMP),synchronous OMP(SOMP),and deep neural network(DNN)channel estimation algorithms in terms of normalized mean squared error(NMSE)performance,thereby validating the feasibility of the proposed approach.

关键词： intelligent reflecting surface millimeter wave channel estimation deep learning

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