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Frequency-dependent Electrical Capacitance and Resistance of Ultra-high Performance Concrete and Their Responses to Compressive Strain

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Journal of Wuhan University of Technology(Materials science) 2024年第4期39卷 968-978页

作者：吴瑜孙明清 ZHU Lutao SONG Qiulei CHEN Jianzhong Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics School of ScienceWuhan University of TechnologyWuhan 430070China School of Civil Engineering and Architecture Hubei University of Arts and ScienceXiangyang 441053China Suzhou Concrete and Cement Products Research institude Co. LtdSuzhou 215026China

The frequency-dependent electrical properties and strain self-sensing behaviour of ultra-high performance concrete(UHPC)as cement-based stress/strain self-sensing(CBSS)smart materials were investigated in the frequency range from 100 Hz to 300 *** using the electrical parameters of the equivalent electric circuit model,the quantitative relations of capacitance and conductance of CBSS with the measurement frequency were *** capacitance and the conductance exhibit power-law type dependence on the measurement *** calculated capacitance values at frequencies beyond 2 kHz and conductance values are consistent with the experimental *** sweep-frequency test and the fixed-frequency test were performed to examine effects of the excitation frequencies on strain self-sensing properties of *** fractional change in capacitance(FCC)and resistance(FCR)of CBSS are frequency-dependent in the frequency range from 100 Hz to the f_(B),but frequency-independent in the frequency range from the f_(B)to 300 *** f_(A)and the f_(B)are 1.7-4.0 kHz and 11-78 kHz depending on the fiber dosages,*** and FCR reach their maximum at the f_(A)and 100 Hz,*** responses of capacitance and resistance of CBSS to strain show good repeatability during cyclic *** the fiber dosage increases,capacitance-based sensitivity to strain increases initially and then decreases at the f_(A),and resistance-based sensitivity to strain of CBSS increases with increasing fiber contents.

关键词： UHPC strain self-sensing capacitance-based frequency-dependent

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A Fast Insertion Tabu Search with Conflict-Avoidance Heuristic for the Multisatellite Multimode Crosslink Scheduling Problem

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Tsinghua science and Technology 2024年第3期29卷 843-862页

作者： Weiyi Yang Lei He Xiaolu Liu Weican Meng Yingwu Chen College of Systems Engineering National University of Defense TechnologyChangsha 410000China Beijing institude of Tranking and Telecommunication Technology Beijing 100000China

An agile earth-observing satellite equipped with multimode cameras capable of transmitting observation data to other satellites is developed to rapidly respond to requests with multiple observation *** gives rise to the Multisatellite Multimode Crosslink Scheduling(MMCS)problem,which involves allocating observation requests to agile satellites,selecting appropriate timing and observation modes for the requests,and transmitting the data to the ground station via the satellite communication ***,a mixed integer programming model is introduced to include all complex time and operation *** solve the MMCS problem,a two-stage heuristic method,called Fast insertion Tabu Search with Conflict-avoidance(FTS-C)heuristic,is *** the first stage,a conflict-avoidance insertion algorithm is designed to generate a high-quality initial solution by considering the requests transmission and ***,the tabu search-based second stage optimizes the initial ***,an extensive empirical study based on a real-world situation demonstrates that FTS-C can generate a solution with higher quality in less time than other state-of-the-art algorithms and the CPLEX solver.

关键词： earth observation satellites scheduling tabu search heuristic data transmission and download mixedinteger programming model

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Experimental and computational investigation on flow characteristics of rotating cavities with high inlet pre-swirl axial throughflow

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Chinese Journal of Aeronautics 2024年第4期37卷 276-293页

作者： Sipeng WANG Xiang LUO Linji GUO Zeyu WU Yang BAI Zongchao LI Lichun MA School of Energy and Power Engineering Beihang UniversityBeijing 100191China Research institude of Aero-Enigine Beihang UniversityBeijing 100191China National Key Laboratory of science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China Shenyang Aeroengine Research Institute Aero Engine Corporation of ChinaShenyang 110015China

As an integral part of the internal air system of aero-engines,the axial throughflow of the cooling air can interact with the cavity flow between the rotating compressor disks,forming a threedimensional,unsteady,and unstable flow *** flow characteristics in an engine-like rotating multi-stage cavity with throughflow were investigated using particle image velocimetry,flow visualization technology and three-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS)*** focus of current research was to understand the distribution of the mean swirl ratio and its variation with a wide range of non-dimensional parameters in the co-rotating cavity with high inlet pre-swirl axial *** maximum axial Reynolds number and rotational Reynolds numbers could reach 4.41×10^(4)and 1.24×10^(6),*** velocity measurement results indicate that the mean swirl ratio is greater than 1 and decreases with an increase in the radial *** flow structure is dominated by the Rossby number,and two different flow patterns (flow penetration and flow stratification) are identified and confirmed by flow visualization *** the absence of buoyancy,the flow penetration caused by the precession of the throughflow makes it easier for the throughflow to reach a high radius *** consistency of results between measurements and numerical calculations is *** study provides a theoretical basis and data support for toroidal vortex breakdown,which is of practical significance for the design of high-pressure compressor cavities.

关键词： Compressor Axial throughflow Rotating cavity flow Particle image velocimetry Unsteady RANS Flow pattern

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Experimental study of solid-liquid origami composite structures with improved impact resistance

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 118-123页

作者： Shuheng Wang Zhanyu Wang Bei Wang Zhi Liu Yunzhu Ni Wuxing Lai Shan Jiang Yong An Huang AML Department of Engineering MechanicsLaboratory of Flexible Electronics TechnologyTsinghua UniversityBeijing 100084China Institute of Advanced Structure Technology Beijing Key Laboratory of Lightweight Multi-functional Composite Materials and StructuresBeijing Institute of TechnologyBeijing 100081China Hangzhou Institute of Technology Xidian UniversityHangzhou 311200China Nanjing Research institude of Electronics Technology Nanjing 210039China The Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

In this paper,a liquid-solid origami composite design is proposed for the improvement of impact *** this design strategy,Kresling origami composite structures with different fillings were designed and fabricated,namely air,water,and shear thickening fluid(STF).Quasi-static compression and drop-weight impact experiments were carried out to compare and reveal the static and dynamic mechanical behavior of these *** results from drop-weight impact experiments demonstrated that the solid-liquid Kresling origami composite structures exhibited superior yield strength and reduced peak force when compared to their empty ***,the Kresling origami structures filled with STF exhibited significantly heightened yield strength and reduced peak *** example,at an impact velocity of 3 m/s,the yield strength of single-layer STF-filled Kresling origami structures increased by 772.7%and the peak force decreased by 68.6%.This liquid-solid origami composite design holds the potential to advance the application of origami structures in critical areas such as aerospace,intelligent protection and other important *** demonstrated improvements in impact resistance underscore the practical viability of this approach in enhancing structural performance for a range of applications.

关键词： Solid-liquid design Origami structure Impact resistance Shear thickening fluid

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MICROCOSMIC BOUND THEOREM OF DAYCY'S LAW AND ITS APPLICATION

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Applied Mathematics and Mechanics(English Edition) 2004年第3期25卷 279-287页

作者：许友生刘慈群林机 institude of Mathematics & Physics & Information science Zhejiang Normal University institude of Porous Flow and Fluid Mechanics Academia Sinica

By combining Chapman-Enskog expansion with the BGK approximation to Baltzmann equation and Navier-Stokes equation was obtained. And an expression of (Darcy's) law was obtained through taking variable average over Navier-Stokes equation on some representative space in porous media,and finally an example was taken to prove its reliability.

关键词： Darcy's law Boltzmann equation Navier-Stokes equation Chapman-Enskog expansion

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Numerical Simulation of 2-D Radiation-Drive Ignition Implosion Process

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Communications in Theoretical Physics 2013年第6期59卷 737-744页

作者：勇珩宋鹏翟传磊康洞国谷建法杭旭登古培俊江松 institude of Applied Physics and Computational Mathematics

A Lagrangian compatible radiation hydrodynamic algorithm and the nuclear dynamics computing module are developed and implemented in the LARED Integration code, which is a radiation hydrodynamic code based on the 2-D cylindrical coordinates for the numerical simulation of the indirect-drive Inertial Confined Fusion. A number of 1-D and 2-D ignition implosion numerical simulations by using the improved LARED Integration code (ILARED) are presented which show that the 1-D numerical results are consistent with those computed by the 1-D radiation hydrodynamic code RDMG, while the simulation results of the 2-D low-mode radiative asymmetry and hydrodynamic instability growth,according to the physical analysis and anticipation, are satisfactory. The capsules driven by the sources from SGII experiments are also simulated by ILARED, and the fuel shapes agree well with the experimental results. The numerical simulations demonstrate that ILARED can be used in the simulation of the 1-D and 2-D ignition capsule implosion using the multi-group diffusion model for radiation.

关键词： LARED Integration code ignition implosion capsule spherical symmetry Lagrangian compatibleradiation hydrodynamic algorithm

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Topological Effect of Reduced Quantum Trajectory in Coherence and Decoherence

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Communications in Theoretical Physics 2010年第9期54卷 433-438页

作者：史旭光段一士秦志杰 College of science Beijing Forestry University institude of Theoretical Physics Lanzhou University School of Physics and Engineering Zhengzhou University

The topological expression of the reduced quantum trajectory is given by using C-mapping topological current theory. The topological expression is used in study of the coherence and the decoherence. We find the expression of vorticity for decoherence has a similar form as that for coherence. A topological reason leading to the decoherence is given and a new parameter is defined to indicate the coherence degree. The parameter is different from the damping factor because it relates to the topological structure of the reduced quantum trajectory.

关键词： coherence decoherence topology vorticity

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Targets detecting in the ocean using the cross-polarized channels of fully polarimetric SAR data

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Acta Oceanologica Sinica 2015年第1期34卷 85-93页

作者： WANG Yunhua LIU Xiaoyan LI Huimin ZHANG Yanmin Ocean Remote Sensing Institute Ocean University of China College of Information science & Engineering Ocean University of China The First institude of Oceanography

Azimuth ambiguities （ghost targets） discrimination is of great interest with the development of a synthet- ic aperture radar （SAR）. And the azimuth ambiguities are often mistaken as actual targets and cause false alarms. For actual targets, HV channel signals acquired by a fully polarimetric SAR are approximately equal to a VH channel in magnitude and phase, i.e., the reciprocity theorem applies, but shifted in phase about ±π for the first-order azimuth ambiguities. Exploiting this physical behavior, the real part of the product of the two cross-polarized channels, i.e. （SHVSVH）, hereafter called A12r, is employed as a new parameter for a target detection at sea. Compared with other parameters, the contrast of A12r image between a target and the surrounding sea surface will be obviously increased when A12r image is processed by mean filtering algo- rithm. Here, in order to detect target with constant false-alarm rates （CFARs）, an analytical expression for the probability density function （pdf） ofA12r is derived based on the complexWishart-distribution. Because a value of A12r is greater/less than 0 for real target/its azimuth ambiguities, the first-order azimuth ambiguities can be completely removed by this A12r-based CFAR technology. Experiments accomplished over C-band RADARSAT-2 fully polarimetric imageries confirm the validity.

关键词： azimuth ambiguities polarimetric SAR CFAR detection algorithm

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Development of ecohydrological assessment tool and its application

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science China(Technological sciences) 2009年第7期52卷 1947-1957页

作者： LIU ChangMing YANG ShengTian WEN ZhiQun WANG XueLei WANG YuJuan LI Qian SHENG HaoRan institude of water science Beijing Normal UniversityBeijing 100875China State Key Laboratory of Remote Sensing science Beijing Key Laboratory for Remote Sensing of Environment and Digital CitiesSchool of GeographyBeijing Normal UniversityBeijing 100875China Key Laboratory of water Resources and Related Land Surface Processes Institute of Geographical Sciences and Natural ResourcesChinese Academy of SciencesBeijing 100101China

The development of Hydro-Informatic Modelling System (HIMS) provides an integrated platform for hydrological simulation. To extend the application of HIMS, an ecohydrological modeling system named ecohydrological assessment tool (EcoHAT) has been developed. Integrating parameter-management tools, RS (remote sensing) inversion tools, module-design tools and GIS analysis tools, the EcoHAT provides an integrated tool to simulate ecohydrological processes on regional scale, which develops a new method on sustainable use of water. EcoHAT has been applied to several case studies, such as, the Yellow River Basin, the acid deposition area in Guizhou province and the riparian catchment of Guanting reservoir in Beijing. Results prove that EcoHAT can efficiently simulate and analysis the ecohydrological processes on regional scale and provide technical support to integrated water resources management on basin scale.

关键词： EcoHAT ecohydrology distributed model remote sensing

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A Multi-Agent Based Model for User Interest Mining on Sina Weibo

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China Communications 2022年第2期19卷 225-234页

作者： Meijia Wang Qingshan Li School of Electronic Information and Artifical Intelligence Shaanxi University of Science and TechnologyXi’an 710021China Software Engineering institude Xidian UniversityXi’an 710071China

User interest mining on Sina Weibo is the basis of personalized recommendations,advertising,marketing promotions,and other *** great progress has been made in this area,previous studies have ignored the differences among users:the varied behaviors and habits that lead to unique user data *** is unreasonable to use a single strategy to mine interests from such varied user ***,this paper proposes an adaptive model for user interest mining based on a multi-agent system whose input includes self-descriptive user data,microblogs and *** method has the ability to select the appropriate strategy based on each user’s data *** experimental results show that the proposed method performs better than the baselines.

关键词： multi-agent system user interest mining adaptive model Sina Weibo online social network

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