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Anisotropic characteristics of layered backfill:Mechanical properties and energy dissipation

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3188-3208页

作者： huisheng qu Lang Liu Yonglu Suo Mengbo Zhu Pan Yang Caixing Zhang Geng Xie Energy School Xi’an University of Science and TechnologyXi’an710054China Key Laboratory of Western Mines and Hazards Prevention Ministry of Education of ChinaXi’an710054China

Layered backfill is commonly used in mining operations,and its mechanical behavior is strongly influenced by delamination *** this study,13 specimens with different numbers of delamination and delamination angle were prepared to investigate the anisotropic mechanical behavior,energy dissipation characteristics and crack development of backfill.P-wave velocity,uniaxial compression,scanning electron microscope(SEM),and acoustic emission(AE)experiments were *** results indicate that:(1)The P-wave velocity has linear and elliptical relationships with the number of delamination surface and delamination angle,respectively;the strength,delamination parameters and P-wave velocity show a high degree of coincidence in terms of their function relationship,which can realize the rapid prediction of strength.(2)The microstructure of the delaminated surface is looser than that of the matrix,leading to a decrease in strength and an increase at the pore-fissure compaction *** number and angle of delamination increase linearly with the anisotropy coefficient.(3)The energy evolution in angle-cut backfill can be divided into four stages,with a decrease in the proportion of elastic energy at the initiation stress and peak stress with increasing number of delamination planes and delamination angle.(4)Crack development increases with the number of delamination surface and delamination angle,resulting in a decrease in energy dissipation coefficient and peak AE *** findings provide valuable insights for the design of filling materials and processes in mining operations.

关键词： Layered backfill Delamination par ameters Anisotropic mechanical behavior P-wave velocity Energy dissipation characteristics Acoustic emission(AE)

不同裂隙角度岩石相似试样力学特性及声发射特性研究

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煤矿安全 2019年第11期50卷 54-57页

作者：索永录屈慧升西安科技大学能源学院陕西西安710054 教育部西部矿井灾害防治重点实验室陕西西安710054

为了研究岩石相似材料在不同倾角预制裂隙影响下的力学特性的变化规律,利用河沙、水泥、石膏等材料制作岩石相似试样,并对制作成功的岩石相似试样制作不同角度的裂隙,最终对含不同倾角的试样进行单轴压缩试验,研究其力学特性的变化规律... 详细信息

为了研究岩石相似材料在不同倾角预制裂隙影响下的力学特性的变化规律,利用河沙、水泥、石膏等材料制作岩石相似试样,并对制作成功的岩石相似试样制作不同角度的裂隙,最终对含不同倾角的试样进行单轴压缩试验,研究其力学特性的变化规律。研究得到含有预制裂隙试样的峰值强度随裂隙倾角的增大呈对数关系增长;同时其峰值应变随裂隙倾角的增大呈指数关系增长;含预制裂隙试样的AE事件累计数及能量强度大致变化趋势相近,可分为压实萌生阶段、弹性稳定增长阶段、破坏剧烈增长阶段;AE事件累计数随着预制裂隙倾角的增大不断增大,能量强度也随着预制裂隙倾角的增大不断增大。

关键词：预制裂隙单轴压缩峰值强度峰值应变物理相似模拟

Time-Periodic Solutions to quasilinear Hyperbolic Systems on General Networks

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 41-72页

作者： Peng qu School of Mathematical Sciences Fudan UniversityShanghai 200433China

For quasilinear hyperbolic systems on general networks with time-periodic boundary-interface conditions with a dissipative structure,the existence and stability of the time-periodic classical solutions are discussed.

关键词： Time-periodic solution quasilinear hyperbolic system General net-work Classical solution Asymptotic stability

Flat jet electrochemical milling of TC4 alloy with tailoring backward parallel flow

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Chinese Journal of Aeronautics 2024年第4期37卷 574-592页

作者： Huanghai KONG Ningsong qu College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In flat jet electrochemical milling, the electrolyte forms a backward parallel flow after impacting the workpiece, resulting in a weak current density distribution on the workpiece. Poor surface quality usually occurs on the machined titanium alloy surface because it inevitably suffers from the weak current density. In this study, a method of flat jet electrochemical milling with tailoring the backward parallel flow was proposed to eliminate the negative effects caused by the weak current density. Multiphysics simulations are carried out to comprehend the mechanism of flat jetEC milling with tailoring backward parallel flow and better construct the novel tool *** on flat jet electrochemical milling of TC4 alloy with and without tailoring backward parallel flow are conducted. The results reveal that, compared with flat jet electrochemical milling without tailoring backward parallel flow, the recommended tool reduces the surface roughness by86% to 93%, and improves the material removal rate by 93% to 163% with different feed ***, the recommended tool is more conducive to maintaining the inherent hardness of the material. Finally, a surface with low Sa of 0.37 μm is obtained.

关键词： Flat jet electrochemical milling TC4 alloy Surface roughness Micro-hardness Material removal rate

Pathways toward a pollution-free planet and challenges

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 3-8页

作者： Jiuhui qu Jiaping Chen School of Environment Tsinghua UniversityBeijing 100084China College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060China

The mission of“Establishment of Zero-Pollution Earth”defined by United Nations Environment Programme aims at creation of a clean,safe and prosperous home for all human *** is of rational choice from each individual to protect our environment and demonstrates our great ambition to achieve our *** key message given in this article is that,zero pollution does not mean no discharge of pollutants and instead it can be achievable through optimizing and controlling a sound balance between pollutants discharge and capacities of decontamination through treatment and natural environmental accumulation,which can be termed as“Principle of Equilibrium”between pollution and *** on this principle,we propose and illustrate several key factors and synergistic pathways toward a pollution-free planet:quantitative determination on purification and wastewater;source control through green measures;minimization of negative side-effects;precise management through digitalized systems;and keeping sound balance between pollutants and natural *** should be noted that we would face a series of difficulties and challenges in moving forward to“Zero-Pollution Earth”.We should further develop theories,principles and tools to achieve the balance between quantity of pollutants and decontamination *** should work together to break through the bottleneck limited by“Principle of equilibrium”to establish new environmental remediation systems leading to“Zero-Pollution Earth”.

关键词： Wastewater treatment Resources Recovery Greenhouse gases Energy Pollution-free

Different Types of Bone Fractures Observed by Terahertz Time-Domain Spectroscopy

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Acta Mechanica Solida Sinica 2024年第3期37卷 468-477页

作者： Minghao Zhang Xianjia Meng Zhiyong Wang Chuanyong qu Chuan qu Donghui Fu Department of Mechanics Tianjin UniversityTianjin300072China Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin300072China

Microcracks are common in compact bone,but their continued propagation can lead to macroscopic *** microcracks cannot be visualized radiographically,necessitating alternative noninvasive methods to identify excessive microcracking and prevent *** this study,terahertz time-domain spectroscopy(THz-TDS)was used to examine bone interiors near cracks resulting from loading in bovine tibia *** loading configurations,such as impact,quasi-static loading,and fatigue loading,known to induce different types of micro-scale damage,were *** values of refractive index and absorption coefficient of the bone samples were then determined from the THz-TDS spectra acquired before loading and after *** study revealed that different loading configurations led to varying terahertz optical coefficients associated with various types of bone ***,the refractive index notably increased under fatigue loading but remained relatively stable during quasi-static *** absorption coefficient of bone decreased only under fatigue ***,samples were subjected to axial and radial impacts without sustaining *** indicated that in the undamaged state,the change in refractive index was smaller compared to after impact failure,while the change in absorption coefficient remained consistent after *** radial impact loading,changes in refractive index and absorption coefficient were significantly more pronounced than under axial *** to loading,the measured value of refractive index was 2.72±0.11,and the absorption coefficient was 6.33±0.09 mm^(−1)at 0.5 THz.

关键词： Terahertz time-domain spectroscopy Bone Microdamage Noninvasive method

Digital Twin Technology of Human-Machine Integration in Cross-Belt Sorting System

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 195-212页

作者： Yanbo qu Ning Zhao Haojue Zhang School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China Institute of Microelectronics of the Chinese Academy of Sciences Beijing 100029China Wayzim Technology Co. LtdWuxi 214108China Business School Beijing Technology and Business UniversityBeijing 100048China

The Chinese express delivery industry processes nearly 110 billion items in 2022,averaging an annual growth rate of 200%.Among the various types of sorting systems used for handling express items,cross-belt sorting systems stand out as the most ***,despite their high degree of automation,the workload for operators has intensified owing to the surging volume of express *** the era of Industry 5.0,it is imperative to adopt new technologies that not only enhance worker welfare but also improve the efficiency of cross-belt *** a balance between efficiency in handling express items and operator well-being is *** twin technology offers a promising solution in this respect.A realization method of a human-machine integrated digital twin is proposed in this study,enabling the interaction of biological human bodies,virtual human bodies,virtual equipment,and logistics equipment in a closed loop,thus setting an operating *** technologies in the proposed framework include a collection of heterogeneous data from multiple sources,construction of the relationship between operator fatigue and operation efficiency based on physiological measurements,virtual model construction,and an online optimization module based on real-time *** feasibility of the proposed method was verified in an express distribution center.

关键词： Industry 5.0 Cross-belt sorting system Human-machine integrated Digital twin Online optimization

A Review on the Mullins Effect in Tough Elastomers and Gels

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Acta Mechanica Solida Sinica 2024年第2期37卷 181-214页

作者： Lin Zhan Shaoxing qu Rui Xiao MOE Key Lab of Disaster Forecast and Control in Engineering College of Mechanics and Construction EngineeringJinan UniversityGuangzhou510632China State Key Laboratory of Fluid Power and Mechatronic System Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering MechanicsZhejiang UniversityHangzhou310027China

Tough elastomers and gels have garnered broad research interest due to their wide-ranging potential ***,during the loading and unloading cycles,a clear stress softening behavior can be observed in many material systems,which is also named as the Mullins *** this work,we aim to provide a complete review of the Mullins effect in soft yet tough materials,specifically focusing on nanocomposite gels,double-network hydrogels,and multi-network *** first revisit the experimental observations for these soft *** then discuss the recent developments of constitutive models,emphasizing novel developments in the damage mechanisms or network *** phenomenological models will also be briefly *** attention is then placed on the anisotropic and multiaxial modeling *** is demonstrated that most of the existing models fail to accurately predict the multiaxial data,posing a significant challenge for developing future anisotropic models tailored for tough gels and elastomers.

关键词： Mullins effect Double-network hydrogels Nanocomposite gels Multi-network elastomers Anisotropic damage model Multiaxial model

Bacterial Cellulose/Zwitterionic Dual-network Porous Gel Polymer Electrolytes with High Ionic Conductivity

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 596-605页

作者：侯朝霞 WANG Haoran qu Chenying Liaoning Province Key Laboratory of Micro-nano Materials Research and Development School of Mechanical EngineeringShenyang UniversityShenyang 110044China

Bacterial cellulose(BC)was innovatively combined with zwitterionic copolymer acrylamide and sulfobetaine methacrylic acid ester[P(AM-co-SBMA)]to build a dual-network porous structure gel polymer electrolytes(GPEs)with high ionic *** dual network structure BC/P(AM-co-SBMA)gels were formed by a simple one-step polymerization *** results show that ionic conductivity of BC/P(AM-co-SBMA)GPEs at the room temperature are 3.2×10^(-2) S/cm@1 M H_(2)SO_(4),4.5×10^(-2) S/cm@4 M KOH,and 3.6×10^(-2) S/cm@1 M NaCl,*** active carbon(AC)as the electrodes,BC/P(AM-co-SBMA)GPEs as both separator and electrolyte matrix,and 4 M KOH as the electrolyte,a symmetric solid supercapacitors(SSC)(AC-GPE-KOH)was assembled and *** specific capacitance of AC electrode is 173 F/g and remains 95.0%of the initial value after 5000 cycles and 86.2%after 10,000 cycles.

关键词： bacterial cellulose zwitterion gel polymer electrolytes ionic conductivity dual-network structure