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On the behaviour characterization of metallic cellular materials under impact loading

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Acta Mechanica Sinica 2010年第6期26卷 837-846页

作者： dai-ning fang Yu-Long Li Han Zhao College of Engineering Peking University 100871 BeijingChina School of Aeronautics Northwestern Polytechnical University 710072 Xi'anChina Laboratoire de Mecanique et Technologie ENS-Cachan/CNRS-UMR8535/Universite Pierre and Marie Curie61avenue du president Wilson 94235 Cachan CedexFrance

This paper reviews the common mechanical features of the metallic cellular material under impact loading as well as the characterization methods of such behaviours. The main focus is on the innovations of various testing methods at impact loading *** aspects were discussed in details.（1） The use of soft nylon Hopkinson/Kolsky bar for an enhanced measuring accuracy in order to assess if there is a strength enhancement or not for this class of cellular materials under moderate impact loading;（2） The use of digital image correlations to determine the strain fields during the tests to confirm the existence of a pseudo-shock wave propagation inside the cellular material under high speed impact：（3） The use of new combined shear compression device to determine the loading envelop of cellular materials under impact multiaxial loadings.

关键词： Foam Honeycomb Lattice Hopkinson bar Rate sensitivity

Mechanics of advanced fiber reinforced lattice composites

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Acta Mechanica Sinica 2010年第6期26卷 825-835页

作者： Hua-Lin Fan Tao Zeng dai-ning fang Wei Yang College of Mechanics and Materials Hohai University Nanjing 210098China Key Laboratory for Advanced Building Materials of Sichuan Province Southwest University of Science and Technology Mianyang 621010China College of Civil Engineering and Architecture Harbin University of Science and TechnologyHarbin 150080China College of Engineering Peking University Beijing 100871China University Office Zhejiang University Hangzhou 310058China

Fiber reinforced lattice composites are lightweight attractive due to their high specific strength and specific *** the past 10 years,researchers developed three-dimensional（3D） lattice trusses and two-dimensional （2D） lattice grids by various methods including interlacing, weaving,interlocking,filament winding and molding hot- *** lattice composites have been applied in the fields of radar cross-section reduction,explosive absorption and heat-resistance. In this paper,topologies of the lattice composites, their manufacturing routes,as well as their mechanical and multifunctional applications,were surveyed.

关键词： Lattice composites Mechanical behaviors Fabrication Multifunction

Design of Protograph LDPC-Coded MIMO-VLC Systems with Generalized Spatial Modulation

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China Communications 2024年第3期21卷 118-136页

作者： dai Lin fang Yi Guan Yongliang Mohsen Guizani School of Information Engineering Guangdong University of TechnologyGuangzhou 51006China The State Key Laboratory of Integrated Services Networks Xidian UniversityXi’an 710126China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore Department of Machine Learning Mohamed Bin Zayed University of Artificial Intelligence(MBZUAI)Abu DhabiUnited Arab Emirates

This paper investigates the bit-interleaved coded generalized spatial modulation(BICGSM) with iterative decoding(BICGSM-ID) for multiple-input multiple-output(MIMO) visible light communications(VLC). In the BICGSM-ID scheme, the information bits conveyed by the signal-domain(SiD) symbols and the spatial-domain(SpD) light emitting diode(LED)-index patterns are coded by a protograph low-density parity-check(P-LDPC) code. Specifically, we propose a signal-domain symbol expanding and re-allocating(SSER) method for constructing a type of novel generalized spatial modulation(GSM) constellations, referred to as SSERGSM constellations, so as to boost the performance of the BICGSM-ID MIMO-VLC ***, by applying a modified PEXIT(MPEXIT) algorithm, we further design a family of rate-compatible P-LDPC codes, referred to as enhanced accumulate-repeat-accumulate(EARA) codes,which possess both excellent decoding thresholds and linear-minimum-distance-growth property. Both analysis and simulation results illustrate that the proposed SSERGSM constellations and P-LDPC codes can remarkably improve the convergence and decoding performance of MIMO-VLC systems. Therefore, the proposed P-LDPC-coded SSERGSM-mapped BICGSMID configuration is envisioned as a promising transmission solution to satisfy the high-throughput requirement of MIMO-VLC applications.

关键词： bit-interleaved coded modulation generalized spatial modulation multiple-input multipleoutput protograph LDPC codes visible light communication

Bald Eagle Search Optimization Algorithm Combined with Spherical Random Shrinkage Mechanism and Its Application

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Journal of Bionic Engineering 2024年第1期21卷 572-605页

作者： Wenyan Guo Zhuolin Hou fang dai Xiaoxia Wang Yufan Qiang Department of Applied Mathematics School of ScienceXi'an University of TechnologyXian 710054ShaanxiChina

Over the last two decades,stochastic optimization algorithms have proved to be a very promising approach to solving a variety of complex optimization *** eagle search optimization(BES)as a new stochastic optimization algorithm with fast convergence speed has the ability of prominent optimization and the defect of collapsing in the local *** avoid BES collapse at local optima,inspired by the fact that the volume of the sphere is the largest when the surface area is certain,an improved bald eagle search optimization algorithm(INMBES)integrating the random shrinkage mechanism of the sphere is ***,the INMBES embeds spherical coordinates to design a more accurate parameter update method to modify the coverage and dispersion of the ***,the population splits into elite and non-elite groups and the Bernoulli chaos is applied to elite group to tap around potential solutions of the *** non-elite group is redistributed again and the Nelder-Mead simplex strategy is applied to each group to accelerate the evolution of the worst individual and the convergence process of the *** results of Friedman and Wilcoxon rank sum tests of CEC2017 in 10,30,50,and 100 dimensions numerical optimization confirm that the INMBES has superior performance in convergence accuracy and avoiding falling into local optimization compared with other potential improved algorithms but inferior to the champion algorithm and ranking *** three engineering constraint optimization problems and 26 real world problems and the problem of extracting the best feature subset by encapsulated feature selection method verify that the INMBES’s performance ranks first and has achieved satisfactory accuracy in solving practical problems.

关键词： Bald eagle search optimization algorithm Spherical coordinates Chaotic variation Simplex method Encapsulated feature selection

Weight Analysis of Impact Factors of Interbedded Anti-Inclined Slopes Block-Flexure Toppling Based on Support Vector Regression

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Journal of Earth Science 2024年第2期35卷 568-582页

作者： Bocheng Zhang Huiming Tang Yibing ning Kun fang Ding Xia Department of Engineering Geology and Geotechnical Engineering Faculty of EngineeringChina University of GeosciencesWuhan430074China Badong National Observation and Research Station of Geohazards China University of GeosciencesWuhan430074China College of Geological Engineering and Geomatics Chang’an UniversityXi’an710054China

Block-flexure toppling failure is frequently encountered in interbedded anti-inclined rock(IAR)slopes,and seriously threatens the construction of hydropower *** this study,we first investigated the Lean Reservoir area’s geological setting and the Linda landslide’s ***,uniform design and random design were used to design 110 training datasets and 31 testing datasets,***,the toppling response was obtained by using the discrete element ***,support vector regression was used to obtain the influence weights of 21 impact *** results show that the influence weight of the slope angle and rock formation dip angle on the toppling deformation among tertiary impact factors is 25.96%and 17.28%,respectively,which are much greater than the other 19 impact factors within the research *** the primary impact factors,the influence weight is sorted from large to small as slope geometry parameters,joints parameters,and rock mechanics *** parameters,especially the geometric parameters,cannot be ignored when evaluating the stability of IAR *** numerical simulation,it was qualitatively determined that failure surfaces of slopes were controlled by cross joints and that the rocks in the slope toe play a role in preventing slope deformation.

关键词： interbedded anti-inclined slopes block-flexure toppling impact factors numerical simulation support vector regression engineering geology

Study on the flow structure in curved open channels with suspended vegetation using multi relaxation time lattice Boltzmann method

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Journal of Hydrodynamics 2024年第2期36卷 300-315页

作者： He-fang Jing Qiao-ling Zhang Wei-hong Wang Zong-ning Zhang School of Mathematics and Information Science North Minzu UniversityYinchuan750021China School of Civil Engineering North Minzu UniversityYinchuan750021China Department of Basic Courses Zhengzhou University of Science and TechnologyZhengzhou450064China

Suspended vegetation in rivers,lakes,reservoirs and canals can change flow structure,which will in turn affect the sediment transport and cause the variation of water ecological *** order to study the characteristics of bend flow through suspended vegetation,three-dimensional numerical simulations are carried out by using the multi-relaxation-time lattice Boltzmann method(MRT-LBM).The drag force induced by vegetation is added in the velocity correction in the equilibrium distribution and a hybrid format combined bounce and specular reflection scheme is applied in the solid-fluid *** the validation of this model,six cases are designed to conduct the numerical simulations according to the root depth and the arrangement of *** simulated results show that the suspended vegetation can redistribute the flow structure in curved open *** the arrangement of suspended vegetation,the main flow moves to the side without vegetation,and the distribution of velocity tends to be balanced when vegetation is arranged on the entire cross section,the range of circulating current is reduced from the whole cross section to the local position without vegetation,however,the circulating current can still exist in the curve where the suspended vegetation enters less than half of the water *** addition,it can also be concluded that the suspended vegetation can affect the lateral gradient of flow velocity,and the bed shear stress in the curved channel.

关键词： Multi-relaxation-time lattice Boltzmann method(MRT-LBM) suspended vegetation curved open channel circulating current bed shearstress

Multi-path navigation method using solar panel-reflected solar oscillations for Earth satellites

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Science China(Information Sciences) 2024年第7期67卷 327-328页

作者： Yuqing YANG Haonan YANG Xiaolin ning Weiren WU Jiancheng fang School of Instrument Science & Opto-electronics Engineering Beihang University Lunar Exploration and Space Program Center China National Space Administration

Several autonomous navigation methods have been studied to reduce reliance on the ground stations. Geomagnetic navigation, gravity gradient navigation, and celestial navigation using optical sensors are typical autonomous navigation methods. Geomagnetic and gravity gradient navigation have low navigation accuracy (1301 m [1] and 235 m [2], respectively) due to the poor accuracy of the geomagnetic and gravity gradient maps.

关键词： Solar panels

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Fracture network types revealed by well test curves for shale reservoirs in the Sichuan Basin,China

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Energy Geoscience 2024年第1期5卷 264-274页

作者： Yanyan Wang Hua Liu Xiaohu Hu Cheng dai Sidong fang State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Petroleum Exploration and Development Research InstituteSinopecBeijing100083China

Pressure buildup testing can be used to analyze fracture network characteristics and conduct quantitative interpretation of relevant parameters for shale gas wells,thus providing bases for assessing the well productivity and formulating proper development *** study establishes a new well test interpretation model for fractured horizontal wells based on seepage mechanisms of shale reservoirs and proposes a method for identifying fracturing patterns based on the characteristic slopes of pressure buildup curves and curve combination *** pressure buildup curve patterns are identified to represent three types of shale reservoirs in the Sichuan Basin,namely the moderately deep shale reservoirs with high pressure,deep shale reservoirs with ultra-high pressure,and moderately deep shale reservoirs with normal *** on this,the relationship between the typical pressure buildup curve patterns and the fracture network types are put *** effects of three types of shale gas reservoir are compared and *** results show that typical flow patterns of shale reservoirs include bilinear flow in primary and secondary fractures,linear flow in secondary fractures,bilinear flow in secondary fractures and matrix,and linear flow in *** fracture network characteristics can be determined using the characteristic slopes of pressure buildup curves and curve *** linear flow in early secondary fractures is increasingly distinct with an increase in primary fracture ***,the bilinear flow in secondary fractures and matrix and the subsequent linear flow in the matrix occur as the propping and density of secondary fractures *** increase in the burial depth,in-situ stress,and stress difference corresponds to a decrease in the propping of primary fractures that expand along different directions in the shale gas wells in the Sichuan *** pressure buildup curve patterns exist in the Sichuan Basin and it

关键词： Shale gas Fractured horizontal well Well testing interpretation Flow pattern characterization Parameter inversion Fracture network characteristics Sichuan basin

A Methodology for Assessing Axial Compressor Stability with Inlet Temperature Ramp Distortion

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Journal of Thermal Science 2024年第3期33卷 856-871页

作者： SUN Dakun GU Benhao ning fangfei fang Yibo DONG Xu XU Dengke SUN Xiaofeng School of Energy and Power Engineering Beihang UniversityBeijing102206China Research Institute of Aero-engine Beihang UniversityBeijing102206China

Based on a small perturbation stability model for periodic flow,the effects of inlet total temperature ramp distortion on the axial compressor are investigated and the compressor stability is quantitatively *** the beginning,a small perturbation stability model for the periodic flow in compressors is proposed,referring to the governing equations of the Harmonic Balance *** stability model is validated on a single-stage low-speed compressor TA36 with uniform inlet ***,the unsteady flow of TA36 with different inlet total temperature ramps and constant back pressure is simulated based on the Harmonic Balance *** on these simulations,the compressor stability is analyzed using the proposed small perturbation ***,the Dynamic Mode Decomposition method is employed to accurately extract pressure *** two parameters of the temperature ramp,ramp rate and Strouhal number,are discussed in this *** results indicate the occurrence and extension of hysteresis loops in the rows,and a decrease in compressor stability with increasing ramp *** performance is divided into two phases,stable and limit,based on the ramp ***,the model predictions suggest that a decrease in period length and an increase in Strouhal number lead to improved compressor *** DMD results imply that for compressors with inlet temperature ramp distortion,the increase of high-order modes and oscillations at the rotor tip is always the signal of decreasing stability.

关键词： axial compressor stability small perturbation model inlet temperature ramp distortion harmonic balance method dynamic mode decomposition method