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Study on force chain evolution of rice straw with different length during vibrational compression

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Particuology 2024年第2期85卷 310-322页

作者： Han Tang Wenlong xu Guixuan zhu Changsu xu Jinwu wang College of Engineering Northeast Agricultural UniversityHarbin150030China

This paper explores the mechanism of force chain evolution and voidage change under vibrational and non-vibrational compression conditions of rice straw of different *** were used to explore the force chain evolution and voidage variation mechanism under different *** re-sults show that under non-vibrational compression,the strong force chain passes from top to bottom in vertical direction and from center to periphery in tangential *** vibrational compression,the force chain passes from top and bottom to center in vertical direction and the force chain evolves from outer ring to interior and exterior in tangential *** number of strong chains,voidage and standard deviation of the mean pressure under vibratory compression are lower than the values under non-vibratory *** promotes stress transfer and enhancement,velocity enhancement and density *** study analyzes the mechanical properties of different lengths straw during vibrational and non-vibrational compression from a detailed viewpoint.

关键词： Straw compression Voidage Discrete element method Mechanical properties Force chain transmission

Interface healing mechanism of fine-grained Ni-Co-based superalloy during hot-compression bonding

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Journal of Materials Science & Technology 2024年第6期173卷 45-53页

作者： shaofei Ren Xiaolong Bai Sheng Liu Mingyue Sun Bin xu Chuanyong Cui Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China China United Gas Turbine Technology Co. Ltd.Beijing 100016China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The interface healing mechanism of fine-grained Ni-Co-based superalloy during hot-compression bonding(HCB)is *** HCB,the incompatibility of deformation between theγand the primary γ′leads to a large number of dislocation pairs(DP),stacking faults(SF),and micro-twins(MT)in the primary γ′.These defects act as fast channels for elemental diffusion,leading to supersaturation of the primary γ′and promoting the growth of the γ-*** the one hand,the primary γ′with a γ-shell moves towards the bonding interface due to anomalous yielding phenomena of the primary γ′and plastic flow during HCB *** increase in the number of defects leads to the growth of γ-γ′heterogeneous epitaxial recrystallization(HERX)grain with coherent structure at the bonding interface,which promotes the bulge of the interface grain boundaries(IGBs).On the other hand,the nucleation and growth of a necklace-like distribution of discontinuous dynamic recrystallization(DDRX)grain at the interface lead to the healing of *** the synergistic action of DDRX and HERX,the mechanical properties of Ni-Co-based superalloy joints through HCB achieve the same level as the base *** finding further enriches the theory of interface healing in HCB.

关键词： Hot-compression bonding Ni-Co-based superalloy Discontinuous dynamic recrystallization Heterogeneous epitaxial recrystallization

Effect of confining pressure on rock breaking by high-pressure waterjet-assisted TBM

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Underground Space 2024年第5期18卷 151-161页

作者： Chen xu Yujie zhu Xiaoli Liu Fei Chen Min zhu Enzhi wang Sijing wang School of Resource and Environment Engineering Wuhan University of TechnologyWuhan 430070China Changjiang Institute of Survey PlanningDesign and ResearchWuhan 430010China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources Wuhan 430010China

High-pressure waterjet-assisted tunnel boring machine(WTBM)is an efficient method for improving the tunneling performance of a tunnel boring machine(TBM)and reducing the wear of its disc cutters in hard rock with high *** pressure directly affects the efficiency of rock breaking and the configuration of the disc *** this study,we evaluated the effect of confining pressure on WTBM rock breaking by developing a self-designed and manufactured experimental system,including confining pressure loading,TBM disc-cutter penetration,and high-pressure *** macro fracture,acoustic emission(AE),peak normal force drop,and specific energy(SE)were analyzed for four different confining pressures(10,20,30,and 35 MPa).The results showed that the cutting depth of the waterjet increased linearly as the waterjet pressure increased and decreased with the gradual increase in the nozzle moving *** expansion and development of cracks formed rock debris,and the size of the rock fragments decreased with an increase in confining *** the waterjet pressure was 280 MPa,the nozzle moving velocity was 800 mm/min and the kerf space was 75 mm,which indicated that the confining pressure,which was 23.16 MPa,minimized the cutting SE under this ***,regardless of the confining pressure,the maximum normal force of WTBM was less than that of a TBM,whereas the SE of WTBM was less than that of complete TBM cutting mode(CTCM).The average force drop and average drop rate of SE were approximately 25%,and 80%,*** results of this study can inspire the design and mechanism of a TBM assisted by a high-pressure waterjet.

关键词： Waterjet Tunnel boring machine(TBM) Confining pressure Specific energy Force drop

Simulation and analysis of soil homogenization drills based on discrete element method and response surface methodology

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Particuology 2024年第5期88卷 128-148页

作者： Zhipeng wang Tong zhu Youzhao wang Song Yang Feng Ma xu Li Institute of Process Equipment and Environmental Engineering School of Mechanical Engineering and AutomationNortheastern UniversityShenyang110819China Liaoning Coning Testing Co. Ltd.Shenyang110170 China

Currently,rotary drilling is one of the main pieces of equipment used for in-situ remediation of contaminated ***,this equipment has problems such as uneven mixing and low utilization efficiency,which affect the efficiency of in-situ soil *** improve the efficiency of in-situ soil remediation,this paper takes contaminated black soil as the research object,and the structural design of the new three-stage soil remediation auger is carried out based on *** mixing process of soil and heavy metal passivator under different motion and structural parameters was investigated by the discrete element method(DEM)and response surface *** experimental design was based on rotational speed,homogenizing mixing time,crushing section pitch,and homogenizing section pitch as factors,and soil fragmentation ratio,the coefficient of dispersion,and torque as optimization *** kinematic and structural parameters of the three-stage auger drill bit were then optimized using the one-factor method,the orthogonal test,and the response surface methodology,*** test method uses a one-way test to determine the central level value of the orthogonal test and a comprehensive balance method to determine the best combination of parameters for the orthogonal test,which is then used as the central value of the response surface test for parameter *** optimal combinations of kinematic and structural parameters of the three-stage auger drill bit are determined and validated using response surface *** optimum combination of parameters was found to be a speed of 129 rpm,a homogenizing mixing time of 24 s,a pitch of 165 mm in the crushing section,and a pitch of 132 mm in the homogenizing *** error between the optimal value of the predicted model using the response surface method and the actual simulated value under the optimal parameters is 4.2%,4.9%,and 5.3%,*** optimized factor parameters provide a refe

关键词： Black soil Mixing homogeneity Orthogonal method Response surface methodology Discrete element method Soil remediation

Indexing dynamic encrypted database in cloud for efficient secure k-nearest neighbor query

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Frontiers of Computer Science 2024年第1期18卷 187-198页

作者： Xingxin LI Youwen zhu Rui xu Jian wang Yushu ZHANG College of Computer Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Mathematical Informatics University of TokyoTokyo 113-8654Japan Guangxi Key Laboratory of Trusted Software Guilin University of Electronic TechnologyGuilin 541004China School of Computer Science China University of GeosciencesWuhan 430074China

Secure k-Nearest Neighbor(k-NN)query aims to find k nearest data of a given query from an encrypted database in a cloud server without revealing privacy to the untrusted cloud and has wide applications in many areas,such as privacy-preservingmachine elearning gand secure biometric *** solutions have been put forward to solve this challenging ***,the existing schemes still suffer from various limitations in terms of efficiency and *** this paper,we propose a new encrypt-then-index strategy for the secure k-NN query,which can simultaneously achieve sub-linear search complexity(efficiency)and support dynamical update over the encrypted database(flexibility).Specifically,we propose a novel algorithm to transform the encrypted database and encrypted query points in the *** indexing the transformed database using spatial data structures such as the R-tree index,our strategy enables sub-linear complexity for secure k-NN queries and allows users to dynamically update the encrypted *** the best of our knowledge,the proposed strategy is the first to simultaneously provide these two *** theoretical analysis and extensive experiments,we formally prove the security and demonstrate the efficiency of our scheme.

关键词： cloud computing secure k-NN query sub-linear complexity dynamicupdate

Chain Rule for Extracting Resilience Procurement Costs from Locational Marginal Prices

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1342-1355页

作者： Yifei wang Tong zhu Tiancong Chen Mohammad Shahidehpour Qingshan xu College of Electrical Engineering Southeast UniversityNanjing 210096China Henan Mechanical&Electrical Vocational College Xinzheng 451191China Illinois Institute of Technology ChicagoIllinois 60616USA IEEE CSEE

Power system resilience procurement costs in N-k contingencies have gained more prominence as number of extreme events continues to increase.A chain rule is presented in this paper for extracting resilience procurement costs from a fully decomposed locational marginal price(LMP)***,power transfer distribution factor(PTDF)matrices with AC power flow(i.e.,AC-PTDF)are ***-PTDF and AC-LODF(line outage distribution factor)equations are derived for N-k contingencies and a fully decomposed LMP model is developed where generation and transmission security components are established for specific ***,resilience procurement costs can be measured at different buses for the proposed security *** of N-k contingencies on resilience procurement costs at specific buses can be determined as proposed security components will gain more insight for resilience procurement in power *** modified IEEE 6-bus and 118-bus systems are adopted to verify effectiveness of the proposed resilience procurement method.

关键词： Line outage distribution factors locational marginal price power system resilience power transfer distribution factor security components

Divergent defluorocarboxylation of α-CF_(3) alkenes with formate via photocatalyzed selective mono-or triple C-F bond cleavage

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Science China Chemistry 2024年第1期67卷 368-373页

作者： Xing-Yu wang Pei xu Wen-Wen Liu Hao-Qiang Jiang Song-Lei zhu Dong Guo xu zhu Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy School of PharmacyXuzhou Medical UniversityXuzhou 22100China

Unprecedented divergent synthesis of gem-difluorovinylacetic acid and glutaric acid derivatives fromα-CF_(3)alkenes with formate as the carbonyl source was *** reaction can undergo selective mono-or triple C-F bond cleavage by simply switching the photocatalyst and hydrogen atom transfer(HAT)catalyst under visible-light-induced conditions at room *** acts as both the C1 source and the reductant through the generation of CO_(2)^(·-)species,which underwent Giese radical addition to electron-deficient alkenes to trigger the consecutive C-F bond cleavage and carboxylation process.

关键词： C-F bond activation defluorocarboxylation carbon dioxide radical anion visible light

Topological non-reciprocal robust waveguide transport

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 39-45页

作者： Ruizhi Dong Yihuan zhu Dongxing Mao xu wang Yong Li Institute of Acoustics Tongji UniversityShanghai 200092China

Devices that surpass the restriction of reciprocity of classical physical waves have brought intriguing possibilities for wave ***-reciprocal acoustic devices that rely on the viscosity of the medium or nonlinear effect have low efficiency and distortion problems respectively,and poor immunity to *** appearance of acoustic topological insulators achieves nonreciprocal transport with high ***,the local nature of topological states means that their appearance depends on a system with a larger *** is,most of the area of a topological device is occupied by useless lattices that do not directly contribute to non-reciprocal *** extra cost of topology protection severely limits the application scenarios of topology states,decreases the cost-effectiveness of topology devices,and is not conducive to device miniaturization and *** this work,we construct an acoustic three-layer heterojunction by introducing two types of domain walls into a conventional quantum Hall effect acoustic topological insulator,and successfully construct a non-reciprocal scattering network that forms topological modes spanning the interlayer *** extended states are still protected by bulk-band topology,making their non-reciprocity robust against *** structure flawlessly realizes the path broadening in a two-dimensional topological system and can accomplish functions such as non-reciprocal acoustic splitting and multichannel *** work opens up opportunities for developing topological-insulator-based non-reciprocal devices in acoustics.

关键词： reciprocal topological topology

Real-time arrival picking of rock microfracture signals based on convolutional-recurrent neural network and its engineering application

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 761-777页

作者： Bing-Rui Chen xu wang Xinhao zhu Qing wang Houlin Xie State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

Accurately picking P-and S-wave arrivals of microseismic(MS)signals in real-time directly influences the early warning of rock mass failure.A common contradiction between accuracy and computation exists in the current arrival picking ***,a real-time arrival picking method of MS signals is constructed based on a convolutional-recurrent neural network(CRNN).This method fully utilizes the advantages of convolutional layers and gated recurrent units(GRU)in extracting short-and long-term features,in order to create a precise and lightweight arrival picking ***,the synthetic signals with field noises are used to evaluate the hyperparameters of the CRNN model and obtain an optimal CRNN *** actual operation on various devices indicates that compared with the U-Net method,the CRNN method achieves faster arrival picking with less performance *** application of large underground caverns in the Yebatan hydropower station(YBT)project shows that compared with the short-term average/long-term average(STA/LTA),Akaike information criterion(AIC)and U-Net methods,the CRNN method has the highest accuracy within four sampling points,which is 87.44%for P-wave and 91.29%for S-wave,*** sum of mean absolute errors(MAESUM)of the CRNN method is 4.22 sampling points,which is lower than that of the other *** the four methods,the MS sources location calculated based on the CRNN method shows the best consistency with the actual failure,which occurs at the junction of the shaft and the second ***,the proposed method can pick up P-and S-arrival accurately and rapidly,providing a reference for rock failure analysis and evaluation in engineering applications.

关键词： Rock mass failure Microseismic event P-wave arrival S-wave arrival Deep learning