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Disc-cutter induced rock breakage mechanism for TBM excavation in rock masses with different joint shear strengths

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Underground Space 2024年第6期19卷 119-137页

作者： Bolong Liu Bo Li Liang Zhang Rui Huang Huicai Gao Shilin Luo Tao Wang Key Laboratory of Rock Mechanics and Geohazards of Zhejiang province Shaoxing UniversityShaoxing 312000China College of Civil Engineering Tongji UniversityShanghai 200092China College of Civil and Architectural Engineering Xi’an University of Science and TechnologyXi’an 710054China College of Civil Engineering Changsha UniversityChangsha 410022China School of transportation Science and Engineering Harbin Institute of TechnologyHarbin 150040China Chongqing research institute of Harbin institute of Technology Harbin Institute of TechnologyChongqing 401151China

When tunnel boring machines(TBMs)excavate through jointed rock masses,the cutting efficiency is strongly affected by the shear strength of joints,the mechanism of which,however,remains poorly *** this study,a series of disc-cutter indentation tests were conducted on granite rock mass specimens with different joint shear *** the indentation,the cracking process was recorded by a digital image correlation(DIC)*** deformation and strength of specimens,cracking behavior,rock breakage mode and cutting efficiency were quantitatively *** addition,to investigate the combined effects of joint shear strength,orientation and spacing on the rock breakage mechanism,numerical rock mass models were established based on a particle flow code *** results reveal that the cracking of primary and secondary cracks changes from the mixed shear-tensile to tensile mode in the initial stage,while the joint shear strength does not affect the cracking mode in the subsequent propagation *** rock breakage mode is classified to an internal block breakage mode,a cross-joint breakage mode and a cutters-dependent breakage *** cross-joint breakage mode is optimal for improving the cutting *** simulation results reveal that the increase in the joint shear strength changes the internal block breakage mode to cross-joint breakage mode for rock masses of particular ranges of joint orientation and *** findings provide basis for improving the TBM cutting efficiency through jointed rock masses.

关键词： Indentation test Joint shear strength Disc cutter Rock breakage mechanism Cutting efficiency

Deformation and stability of the seawall,considering the strength uncertainty of cement mixing piles

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第6期25卷 483-501页

作者： Yuansheng YU Lingling LI Xiangmiao KONG Chengyuan LI Zhen GUO Key Laboratory of Offshore Geotechnics and Material of Zhejiang province College of Civil Engineering and ArchitectureZhejiang UniversityHangzhou310058China Hainan institute Zhejiang UniversitySanya572000China Ninghai Highway and transportation Management Center Ningbo315600China Ninghai Traffic Engineering Construction Management institute Ningbo315600China

The cement mixing (CM) pile is a common method of improving soft offshore ground. The strength growth of CM piles under complex conditions is affected by many factors, especially the cement and moisture contents, and shows significant uncertainty. To investigate the stochasticity of the early strength of CM piles and its impact on the displacement and stability of a seawall, a series of laboratory tests and numerical analyses were carried out in this study. Vane shear tests were conducted on the cement-solidified soil to determine the relationships between the undrained shear strength s_(u) of the cement soil curing in the seawater and the cement content a_(c), as well as the in situ soil moisture content w. It can be inferred that the 24 h undrained shear strength follows a normal distribution. A numerical model considering the random CM pile strength was established to investigate the deformation of the seawall. Due to the uncertainty of CM pile strength, the displacement of the seawall demonstrates a certain discreteness. The decrease of the mean undrained shear strength of CM piles causes a corresponding increase in the average displacement of the seawall. When the mean strength of CM piles is lower than a certain threshold, there is a risk of instability. Furthermore, the heterogeneity of the strength within an individual CM pile also has an impact on seawall displacement. Attention should be paid to the uncertainty of CM pile strength to control displacement and stability.

关键词： Construction uncertainty Cement mixing(CM)pile Strength of cement soil Seawall stability Random finite element method(RFEM) Monte Carlo simulation(MCS)

Nitrogen‑Doped Magnetic‑Dielectric‑Carbon Aerogel for High‑Efficiency Electromagnetic Wave Absorption

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Nano-Micro Letters 2024年第1期16卷 313-327页

作者： Shijie Wang Xue Zhang Shuyan Hao Jing Qiao Zhou Wang Lili Wu Jiurong Liu Fenglong Wang Key Laboratory for Liquid‑Solid Structural Evolution and Processing of Materials Ministry of Education Shandong UniversityJinan 250061People’s Republic of China School of Mechanical Engineering Shandong UniversityJinan 250061People’s Republic of China Shenzhen research institute of shandong University Shenzhen 518057GuangdongPeople’s Republic of China

Carbonbased aerogels derived from biomass chitosan are encountering a flourishing moment in electromagnetic protection on account of lightweight,controllable fabrication and ***,developing a facile construction method of component design with carbon-based aerogels for high-efficiency electromagnetic wave absorption(EWA)materials with a broad effective absorption bandwidth(EAB)and strong absorption yet hits some ***,the nitrogen-doped magnetic-dielectric-carbon aerogel was obtained via ice template method followed by carbonization treatment,homogeneous and abundant nickel(Ni)and manganese oxide(MnO)particles in situ grew on the carbon *** to the optimization of impedance matching of dielectric/magnetic components to carbon aerogels,the nitrogen-doped magnetic-dielectric-carbon aerogel(Ni/MnO-CA)suggests a praiseworthy EWA performance,with an ultra-wide EAB of 7.36 GHz and a minimum reflection loss(RLmin)of−64.09 dB,while achieving a specific reflection loss of−253.32 dB mm−***,the aerogel reveals excellent radar stealth,infrared stealth,and thermal management ***,the high-performance,easy fabricated and multifunctional nickel/manganese oxide/carbon aerogels have broad application aspects for electromagnetic protection,electronic devices and aerospace.

关键词： Electromagnetic wave absorption Wide bandwidth Dielectric-magnetic synergy Multifunction

Development of the electric automatic steering system for agricultural vehicles

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International Journal of Agricultural and Biological Engineering 2024年第1期17卷 209-214页

作者： Guangshun An Chong Yu Juan Du Xiang Yin Youliang Ni Chengqian Jin School of Agricultural Engineering and Food Science Shandong University of TechnologyZibo 255000ShandongChina Nanjing research institute for Agricultural Mechanization of Ministry of Agriculture and Rural Affairs Nanjing 210014China

Automatic guidance of agricultural vehicles requires automatic execution of operation commands received from the navigation controller by using electronically controlled mechanisms for wheel steering,speed changing and work *** steering contributes as a prerequisite technique in automatic and semi-automatic agricultural *** research aimed to develop an electric automatic steering system that was compact in its structure and integrated into original steering mechanism in a simply and convenient way for aftermarket modification.A brushless motor and reducer assembly was utilized to provide an adequate steering torque instead of manual maneuver.A rapid assembling approach was proposed by passing the steering shaft through the hollow output shaft.A digital proportional-integral-differential(PID)algorithm was implemented to calculate the rotation speeds and directions by comparing the desired angle and the actual angle,which was implemented in a printed circuit board with a microcontroller unit(MCU)and interface *** unmanned wheeled tractor was applied as test platform to integrate the newly developed electric automatic steering *** were conducted to evaluate its performance in terms of stability and *** autonomous navigation system guided the tractor along target paths in the field by sending steering commands to the electric automatic steering *** results show that the steering angle error was less than 0.81°when desired steering angle was less than 10°.The lateral error difference was no more than 4.76 cm when repeating following the same target path,which indicated that the electric automatic steering system responded accurately and robustly to steering commands.

关键词： automatic steering automatic navigation agricultural vehicles

Model moisture transport in oil-paper insulation of transformer:Theory and experiment

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High Voltage 2024年第4期9卷 879-887页

作者： Junjie Zhou Zhicheng Wu Yiran Guo Rui Zhang Wenbing Zhu Qiaogen Zhang State Key Laboratory of Electric Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina State Grid shandong Electric Power research institute JinanChina

The insulation performance of oil paper insulation is significantly affected by moisture such that monitoring moisture content is ***,it is difficult to obtain the moisture content accurately due to its dynamic change under multi physical *** the moisture transportation in oil paper insulation under multi physical fields becomes a vital method in solving the problem.A multi physical model describing moisture migration was proposed,which considered the effects of temperature on moisture in different existing states in oil-immersed paper(OIP).The temperature distribution formed a vapour pressure gradient to drive moisture migration and affected migration ***,experiments and simulations of moisture migration were performed,which showed that the experiments were in good agreement with *** results revealed that the temperature gradient caused uneven moisture distribution and the increased temperature reduced OIP moisture *** established model could fully characterise moisture migration under temperature gradient,which provided a theoretical reference for predicting the risk of partial dampness and evaluating insulation performance.

关键词： moisture insulation distribution

Oblique impact breakage unification of nonspherical particles using discrete element method

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Particuology 2024年第7期90卷 61-71页

作者： Di Peng LiGe Wang Yuquan Lin Chongqiang Zhu Xizhong Chen Zhihui Liu Ruihuan Ge Shenzhen research institute of shandong University Shenzhen 518057China institute of Foundation Engineering China Academy of Building ResearchBeijing 100013China Ubiquitous Particle Ltd. TwickenhamLondon TW27AUUK Department of Smart Manufacturing and Engineering Software School of Qilu TransportationShandong UniversityJinan 250061China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China School of transportation and Civil Engineering Shandong Jiaotong UniversityJinan 250357China School of Science and Engineering University of DundeeDundee DD14HNUK Department of Chemical Engineering School of Chemistry and Chemical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Department of Chemical and Biological Engineering University of SheffieldSheffield S13JDUK

Particle breakage commonly occurs during processing of particulate materials,but a mechanistic model of particle impact breakage is not fully *** article presents oblique impact breakage characteristics of nonspherical particles using discrete element method(DEM)*** different particle shapes,***,cuboidal and cylindrical,are *** spheres are agglomerated with bridging bonds to model the breakage characteristics under impact *** effect of agglomerate shapes on the breakage pattern,damage ratio,and fragment size distribution is fully *** using a newly proposed oblique impact model,unified breakage master surfaces are theoretically constructed for all the particle shapes under oblique impact *** developed approach can be applied to modelling particulate processes where nonspherical particles and oblique impact breakage are prevailing.

关键词： Breakage master curve Nonspherical particle Oblique impact Equivalent velocity Discrete element method(DEM) Bonded contact model

Introducing hydroxyl groups to tailor the d-band center of Ir atom through side anchoring for boosted ORR and HER

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Journal of Energy Chemistry 2024年第3期90卷 144-151,I0005页

作者： Qing Lv Meiping Li Xiaodong Li Xingru Yan Zhufeng Hou Changshui Huang Science Center for Material Creation and Energy Conversion School of Chemistry and Chemical EngineeringInstitute of Frontier and Interdisciplinary ScienceShandong UniversityJinan 250100ShandongChina institute of Chemistry Chinese Academy of ScienceBeijing 100191China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002FujianChina

Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic ***,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne(HsGDY),and coordinated with OH as an Ir atomic catalyst(Ir_(1)-N-HsGDY).The electron structures,especially the d-band center of Ir atom,are optimized by these specific coordination ***,the as-synthesized Ir_(1)-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline *** from the unique structure of HsGDY,IrN_(2)(OH)_(3) has been developed and demonstrated to act as the active site in these electrochemical *** those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity,showing a new strategy to design novel electrochemical catalysts.

关键词： Oxygen reduction reaction D-band center Graphdiyne Hydroxyl group Electrocatalysis

Effect of annealing treatment on the microstructure and mechanical properties of warm-rolled Mg-Zn-Gd-Ca-Mn alloys

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2208-2220页

作者： Yifan Song Xihai Li Jinliang Xu Kai Zhang Yaozong Mao Hong Yan Huiping Li Rongshi Chen School of Materials Science and Engineering Shandong University of Science and TechnologyQingdao 266590China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China shandong Key Laboratory of Advanced Aluminium Materials and Technology Binzhou Institute of TechnologyBinzhou 256606China

The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room *** address these problems,a multi-micro-alloyed high-plasticity Mg-1.8Zn-0.8Gd-0.1Ca-0.2Mn(wt%)alloy was developed using the unique role of rare earth and Ca solute *** addition,the influence of the annealing process on the grain size,second phase,texture,and mechanical properties of the warm-rolled sheet at room temperature was analyzed with the goal of developing high-plasticity mag-nesium alloy sheets and obtaining optimal thermal-mechanical treatment *** results show that the annealing temperature has a significant effect on the microstructure and properties due to the low alloying content:there are small amounts of larger-sized block and long string phases along the rolling direction(RD),as well as several spherical and rodlike particle phases inside the *** increas-ing annealing temperature,the grain size decreases and then increases,and the morphology,number,and size of the second phase also change *** particle phase within the grains vanishes at 450℃,and the grain size increases *** the full recrystal-lization stage at 300-350℃,the optimum strength-plasticity comprehensive mechanical properties are presented,with yield strengths of 182.1 and 176.9 MPa,tensile strengths of 271.1 and 275.8 MPa in the RD and transverse direction(TD),and elongation values of 27.4%and 32.3%,***,there are still some larger-sized phases in the alloy that influence its mechanical properties,which offers room for improvement.

关键词： Mg-Zn-Gd-Ca-Mn alloy annealing treatment microstructure texture dynamic recrystallization mechanical properties

Intelligent Fault Diagnosis Method of Rolling Bearings Based on Transfer Residual Swin Transformer with Shifted Windows

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Structural Durability & Health Monitoring 2024年第2期18卷 91-110页

作者： Haomiao Wang Jinxi Wang Qingmei Sui Faye Zhang Yibin Li Mingshun Jiang Phanasindh Paitekul The institute of Marine Science and Technology Shandong UniversityQingdao26623China The School of Control Sciences and Engineering Shandong UniversityJinan250061China Thailand institute of Scientific and Technological research Amphoe Khlong LuangPathum Thani12120Thailand

Due to their robust learning and expression ability for complex features,the deep learning(DL)model plays a vital role in bearing fault ***,since there are fewer labeled samples in fault diagnosis,the depth of DL models in fault diagnosis is generally shallower than that of DL models in other fields,which limits the diagnostic *** solve this problem,a novel transfer residual Swin Transformer(RST)is proposed for rolling bearings in this *** has 24 residual self-attention layers,which use the hierarchical design and the shifted window-based residual *** with transfer learning techniques,the transfer RST model uses pre-trained parameters from ImageNet.A new end-to-end method for fault diagnosis based on deep transfer RST is ***,wavelet transform transforms the vibration signal into a wavelet time-frequency *** signal’s time-frequency domain representation can be represented ***,the wavelet time-frequency diagram is the input of the RST model to obtain the fault ***,our method is verified on public and self-built *** results show the superior performance of our method by comparing it with a shallow neural network.

关键词： Rolling bearing fault diagnosis transformer self-attention mechanism