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Investigation of the failure mechanism and theoretical model of bolt-reinforced shallow tunnel faces with different bolt lengths

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Underground Space 2024年第3期16卷 126-142页

作者： Xiao Zhang Li Yu Mingnian Wang Henghong Yang Ming Lu Zexing Li Langzhou Tang School of Civil Engineering Southwest Jiaotong UniversityChengdu 610036SichuanChina Key Laboratory of Traffic Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610036SichuanChina School of Transportation and Logistics Southwest Jiaotong UniversityChengdu 610036SichuanChina

Using fiberglass bolts to reinforce a tunnel face is a practical auxiliary technology for ensuring tunnel face stability in soft *** reinforcing effect and the economics of this technology are significantly affected by bolt ***,to date,the failure mechanism of bolt-reinforced tunnel faces with different bolt lengths has rarely been *** reveal the failure mechanism of bolt-reinforced shallow tunnel faces,in this study,the stability of bolt-reinforced tunnel faces with different bolt lengths was investigated by using laboratory tests and numerical simulations,and a simplified theoretical model for practical engineering was *** face support pressure and failure pattern for different bolt lengths during the face collapse process were obtained,and the influence of bolt length on face stability was clearly *** specifically,the results show that face stability increases with increasing bolt length,and the reinforcing effect of face bolts is governed by the shear failure at the soil-grout interface first in the stable zone of the tunnel face and then in the failure *** the bolt length in the stable zone is larger than that in the failure zone,face stability will not be improved with increasing bolt length;thus,this bolt length is referred to as the optimal bolt length L_(opt).The L_(opt)value is slightly larger than the initial failure range(in the unreinforced condition)and can be approximately calculated by L_(opt)=(1-0.0133u)D(u is the friction angle of the soil,and D is the tunnel diameter)in practical ***,a simplified theoretical model was established to analyse the stability of reinforced tunnel faces,and the results are in good agreement with both laboratory tests and numerical *** proposed model can be used as an efficient tool for the design of face bolts.

关键词： Failure mechanism Face bolting Tunnel face stability Bolt length Reinforcing mechanism

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Experimental investigation of engineered geopolymer composite for structural strengthening against blast loads

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Defence Technology（防务技术） 2024年第2期32卷 496-509页

作者： Shan Liu Chunyuan Liu Yifei Hao Yi Zhang Li Chen Zhan Li Key Laboratory of Coast Civil Structure Safety of Ministry of Education Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Prefabricated Buildings and Intelligent Construction Hebei University of TechnologyTianjin 300400China Institute of Defense Engineering AMSPLABeijing 100850China Engineering Research Center of Safety and Protection of Explosion&Impact of Ministry of Education Southeast UniversityNanjing 211189JiangsuChina State Key Laboratory of Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of the PLANanjing 210007JiangsuChina

The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil *** geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and ***,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are *** this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and *** experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of *** that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical *** tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact *** was found that EGC could effectively enhance the blast resistance of structural elements in different *** AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly *** plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.

关键词： Engineered geopolymer composites Fiber optimization Strengthening material Blast resistance Masonry wall Reinforced AAC panel Plain concrete slab

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Highly-efficient CoRuO_(x)nanocatalysts for acidic oxygen evolution:The merit of optimum ordering degree of carbon nanotube support

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Particuology 2024年第7期90卷 470-477页

作者： Wenwen Li Yanni Wang Zhenzhen Zhao Meiqi Liu Qing Liang Yuhua Liu Fuxi Liu Zhou Jiang Xu Zou Bingsen Zhang Wei Zhang Key Laboratory of Automobile Materials MOE School of Materials Science&EngineeringJilin Provincial International Cooperation Key Laboratory of High-Efficiency Clean Energy MaterialsElectron Microscopy CenterInternational Center of Future ScienceJilin UniversityChangchun 130012China Shenyang national Laboratory for Materials science Institute of Metal ResearchChinese Academy of Sciences110016ShenyangChina

Hydrogen production from proton exchange membrane water electrolysis is constrained by the sluggish kinetics of the anodic oxygen evolution ***_(2)has attracted considerable attention due to its low reaction overpotential,but its inferior stability remains a major ***,a strategy is proposed to enhance the catalytic activity and stability of CoRuOx nanoparticles by doping Co and regulating the ordering degree of carbon nanotubes(CNTs)by air *** was found that the CoRuOx@CNTs-300 catalyst exhibited the best catalytic activity and stability when the annealing temperature was 300°*** the current density of 10 mA cm−2,the overpotential of this catalyst was only 201 mV,which was nearly 100 mV lower than that of commercial RuO_(2)(300 mV).Surprisingly,there was no significant increase in the overpotential when tested at a current density of 10 mA cm−2 for 50 *** density functional theory calculations indicate that the high activity of the catalyst is due to the electronic coupling of CoRuOx nanoparticles and CNTs,and that the introduction of Co and CNTs improves the electronic structure and solvation energies of the Ru in the active site,dramatically increasing the structural stability.

关键词： Electrocatalysis RuO_(2) CNTs Oxygen evolution reaction

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Nearly degenerate ground states of a checkerboard antiferromagnet and their bosonic interpretation

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science china(Physics,Mechanics & Astronomy) 2024年第1期67卷 84-89页

作者： Haiyuan Zou Fan Yang Wei Ku Key Laboratory of Polar Materials and Devices(MOE) School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China Department of Physics Beijing Institute of TechnologyBeijing 100081China Tsung-Dao Lee Institute Shanghai 200240China Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education) Shanghai 200240China Shanghai Branch Hefei National LaboratoryShanghai 201315China

The spin-1/2 model system with antiferromagnetic(AF) couplings on a J1-J2checkerboard lattice, known as the planar pyrochlore model, is strongly frustrated and associated with a two-to-one dimensional crossover. Using the Projected Entangled Simplex States tensor network ansatz, we identify a large number of nearly degenerate states in the frustrated region(J_(1)

关键词： tensor networks frustrated magnetism dimensional crossover degenerate states

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Granular collapse in fluids:Dynamics and flow regime identification

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Particuology 2024年第9期92卷 30-41页

作者： Hu Tang Bisong Lin Dengming Wang Department of Mechanics and Engineering science School of Civil Engineering and MechanicsKey Laboratory of Mechanics on Disaster and Environment in Western China of Ministry of EducationLanzhou UniversityLanzhou730000China

The collapse of granular material in fluids is a prevalent phenomenon in both natural and industrial processes,displaying a notable sensitivity to initial configuration of the *** study is specifically oriented towards falling process of collapsing material under various fluid conditions,employing the computational fluid dynamics-discrete element method(CFD-DEM)to primarily investigate the dynamics and scaling laws of deposit morphology of collapsed *** a comprehensive analysis of particle sedimentation in fluids,we introduce a refined inertial characteristic time for granular collapse within the inertial ***,we propose modifications to conventional fluid-particle density ratio and Reynolds number,aiming to enhance the accuracy of depicting collapse dynamics and identifying flow regimes across diverse column heights and fluid ***,we construct a phase diagram of flow regimes using modified dimensionless numbers,emphasizing the role of column height in transition between viscous and inertial *** parameters demonstrate enhanced relevance in governing the collapse of immersed granular columns,thereby contributing to a more nuanced understanding of fluid-particle interations in dense granular flows under different regimes.

关键词： Immersed granular material Collapse Dynamic Flow regime Computational fluid dynamics-discrete element method

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Theoretical analysis of the elastic Kelvin-Helmholtz instability in explosive weldings

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Defence Technology（防务技术） 2024年第2期32卷 521-528页

作者： Yuanbo Sun Jianning Gou Cheng Wang Qiang Zhou Rui Liu Pengwan Chen Tonghui Yang Xiang Zhao State Key Laboratory of Explosion science and Technology Beijing Institute of TechnologyBeijing100081China Beijing HIWING Scientific and Technological Information Institute Beijing100084China School of Aerospace Engineering Tsinghua UniversityBeijing100084China

By considering the joint effects of the Kelvin-Helmholtz(KH) and Rayleigh-Taylor(RT) instabilities, this paper presents an interpretation of the wavy patterns that occur in explosive welding. It is assumed that the elasticity of the material at the interface effectively determines the wavelength, because explosive welding is basically a solid-state welding process. To this end, an analytical model of elastic hydrodynamic instabilities is proposed, and the most unstable mode is selected in the solid phase. Similar approaches have been widely used to study the interfacial behavior of solid metals in high-energy-density physics. By comparing the experimental and theoretical results, it is concluded that thermal softening,which significantly reduces the shear modulus, is necessary and sufficient for successful welding. The thermal softening is verified by theoretical analysis of the increase in temperature due to the impacting and sliding of the flyer and base plates, and some experimental observations are qualitatively *** summary, the combined effect of the KH and RT instabilities in solids determines the wavy morphology, and our theoretical results are in good qualitative agreement with experimental and numerical observations.

关键词： Explosive welding Hydrodynamic instabilities Elasticity

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Strain-tuned electronic and valley-related properties in Janus monolayers of SWSiX_(2)(X=N,P,As)

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Chinese Physics B 2024年第9期33卷 487-492页

作者： Yunxi Qi Jun Zhao Hui Zeng New Energy Technology Engineering Laboratory of Jiangsu Province&School of science Nanjing University of Posts and TelecommunicationsNanjing 210023China School of Microelectronics Nanjing University of Science and TechnologyNanjing 210094China

Exploring novel two-dimensional(2D)valleytronic materials has an essential impact on the design of spintronic and valleytronic *** first principles calculation results reveal that the Janus SWSiX_(2)(X=N,P,As)monolayer has excellent dynamical and thermal *** to strong spin–orbit coupling(SOC),the SWSiX_(2)monolayer exhibits a valence band spin splitting of up to 0.49 eV,making it promising 2D semiconductor for valleytronic *** opposite Berry curvatures and optical selection rules lead to the coexistence of valley and spin Hall effects in the SWSiX2 ***,the optical transition energies can be remarkably modulated by the in-plane *** tensile(compressive)in-plane strains can achieve spin flipping in the SWSiN2 monolayer,and induce both SWSiP_(2)and SWSiAs_(2)monolayers transit from semiconductor to *** research provides new 2D semiconductor candidates for designing high-performance valleytronic devices.

关键词： first-principles calculations two-dimensional valleytronic spintronic

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A new method for evaluating the firing precision of multiple launch rocket system based on Bayesian theory

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Defence Technology（防务技术） 2024年第2期32卷 232-241页

作者： Yunfei Miao Guoping Wang Wei Tian College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjingJiangsuChina Institute of Launch Dynamics Nanjing University of Science and TechnologyNanjingJiangsuChina

How to effectively evaluate the firing precision of weapon equipment at low cost is one of the core contents of improving the test level of weapon system.A new method to evaluate the firing precision of the MLRS considering the credibility of simulation system based on Bayesian theory is proposed in this *** of all,a comprehensive index system for the credibility of the simulation system of the firing precision of the MLRS is constructed combined with the group analytic hierarchy process.A modified method for determining the comprehensive weight of the index is established to improve the rationality of the index weight *** Bayesian posterior estimation formula of firing precision considering prior information is derived in the form of mixed prior distribution,and the rationality of prior information used in estimation model is discussed *** the simulation tests,the different evaluation methods are compared to validate the effectiveness of the proposed ***,the experimental results show that the effectiveness of estimation method for firing precision is improved by more than 25%.

关键词： Multiple launch rocket system Bayesian theory Simulation credibility Mixed prior distribution Firing precision

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Synergistic precipitant powered self-assembly of papain for cross-linked enzyme crystals preparation

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Particuology 2024年第2期85卷 102-112页

作者： Qi Hao Pan Guo Honghai Wang Min Su Chunli Li Yuqi Hu Weiyi Su School of Chemical Engineering and Technology Hebei University of TechnologyTianjin300130China national-Local Joint Engineering Laboratory for Energy Conservation of Chemical Process Integration and Resources Utilization Tianjin300130China

In this study,we prepared cross-linked enzyme crystals(CLECs)of papain to further broaden the application of the enzyme with high activity in extreme ***,papain crystals were successfully obtained based on the micro-batch,batch,and expanded batch crystallization ***,ammonium sulfate and polyethylene glycol 6000(PEG6000)were synergistically used as the precipitants,while L-cysteine was applied to enhance the activity of ***,the interaction between L-cysteine and papain was modeled by molecular docking *** was found that L-cysteine could form a hydrogen bond with aspartic acid residue(Asp)at site 158,and the electrostatic attraction with lysine residue(Lys)at site 156 was also quite *** the enzyme crystals were cross-linked by glutaraldehyde at optimized *** papain CLECs were identified by various methods,and it was found that the thermal stability and enzymatic activity both increased compared to the raw *** importantly,it could be applied at more rigorous conditions,for example,pH of 4.

关键词： Papain Cross-linked enzyme crystals L-cysteine Molecular docking Crystallization

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Some Modified Equations of the Sine-Hilbert Type

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Chinese Physics Letters 2024年第4期41卷 1-6页

作者：闫铃娟刘亚杰胡星标 LSEC ICMSECAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical sciences University of Chinese Academy of SciencesBeijing 100049China

Three modified sine-Hilbert(sH)-type equations, i.e., the modified sH equation, the modified damped sH equation, and the modified nonlinear dissipative system, are proposed, and their bilinear forms are *** on these b... 详细信息

关键词： bilinear equations equation

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