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Mesoscopic fracture damage evolution and fractal damage constitutive model of heat-treated red sandstone under direct tensile impact loadings

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Journal of Rock Mechanics and Geotechnical engineering 2025年第1期17卷 323-340页

作者： Shi Liu Yu Jia Yue Zhai Shaoxu Hao school of Mechanics and construction engineering Jinan UniversityGuangzhou510632China school of Geology engineering and Geomatics Chang'an UniversityXi'an710064China

Understanding the mesoscopic tensile fracture damage of rock is the basis of evaluating the deterioration process of mechanical properties of heat-damaged rock. For this, tensile tests of rocks under high-temperature treatment were conducted with a ϕ75 mm split Hopkinson tension bar (SHTB) to investigate the mesoscopic fracture and damage properties of rock. An improved scanning electron microscopy (SEM) experimental method was used to analyze the tensile fracture surfaces of rock samples. Qualitative and quantitative analyses were performed to assess evolution of mesoscopic damage of heat-damaged rock under tensile loading. A constitutive model describing the mesoscopic fractal damage under thermo-mechanical coupling was established. The results showed that the high temperatures significantly reduced the tensile strength and fracture surface roughness of the red sandstone. The three-dimensional (3D) reconstruction of the fracture surface of the samples that experienced tensile failure at 900 °C showed a flat surface. The standard deviation of elevation and slope angle of specimen fracture surface first increased and then decreased with increasing temperature. The threshold for brittle fracture of the heat-damaged red sandstone specimens was 600 °C. Beyond this threshold temperature, local ductile fracture occurred, resulting in plastic deformation of the fracture surface during tensile fracturing. With increase of temperature, the internal meso-structure of samples was strengthened slightly at first and then deteriorated gradually, which was consistent with the change of macroscopic mechanical properties of red sandstone. The mesoscopic characteristics, such as the number, mean side length, maximum area, porosity, and fractal dimension of crack, exhibited an initial decline, followed by a gradual increase. The development of microcracks in samples had significant influence on mesoscopic fractal dimension. The mesoscopic fractal characteristics were used to establis

关键词： High temperature rock mechanics Dynamic direct tension Red sandstone Mesoscopic fracture mechanism Fractal damage constitutive model

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Magnetically-responsive phase change thermal storage materials:Mechanisms,advances,and beyond

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Journal of Energy Chemistry 2025年第2期101卷 485-510页

作者： Yan Gao Yang Li Jinjie Lin Panpan Liu Xiao Chen Ge Wang Beijing Advanced Innovation Center for Materials Genome engineering Beijing Key Laboratory of Function Materials for Molecule & Structure Construction School of Materials Science and Engineering University of Science and Technology Beijing school of Physics and Astronomy Beijing Normal University Shunde Graduate school University of Science and Technology Beijing

Rapid advances in thermal management technology and the increasing need for multi-energy conversion have placed stringent energy efficiency requirements on next-generation shape-stable composite phase change materials(PCMs).Magnetically-responsive phase change thermal storage materials are considered an emerging concept for energy storage systems,enabling PCMs to perform unprecedented functions(such as green energy utilization,magnetic thermotherapy,drug release,etc.).The combination of multifunctional magnetic nanomaterials and PCMs is a milestone in the creation of advanced multifunctional composite ***,a timely and comprehensive review of composite PCMs based on magnetic nanoparticle modification is still ***,we furnish an exhaustive exposition elucidating the cutting-edge advancements in magnetically responsive composite *** delve deeply into the multifarious roles assumed by distinct nanoparticles within composite PCMs of varying dimensions,meticulously scrutinizing the intricate interplay between their architectures and thermophysical ***,we prognosticate future research trajectories,delineate alternative stratagems,and illuminate prospective *** review is intended to stimulate broader academic interest in interdisciplinary fields and provide valuable insights into the development of next-generation magnetically-responsive composite PCMs.

关键词： Magnetic nanoparticles Magnetic-thermal conversion Phase change materials Response mechanism Thermal energy storage

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Nitrogen-cycling processes under long-term compound heavy metal(loids)pressure around a gold mine:Stimulation of nitrite reduction

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Journal of Environmental Sciences 2025年第1期147卷 571-581页

作者： Xuesong Hu Xiaoxia Liu Shuo Zhang Caihong Yu school of Chemical&Environmental engineering China University of Mining and Technology(Beijing)Beijing 100083China Beijing Cultivated Land construction and Protection Center Beijing 100020China

Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil *** microorganisms adapt their metabolism to such conditions,driving alterations in soil *** study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)*** results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)*** microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 ***,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite *** gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key *** results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).

关键词： N cycle Nitrite reduction Nitrite reductase Metagenome Key species

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Morphological Mechanism and Experimental Verification of Self-healing of Basalt-fiber Modified Water-soaked Asphalt

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 171-186页

作者： XIAO Minmin DONG Jinyong LI Chunyan GUO Xu REN Jianguo school of Urban construction and Safety engineering Shanghai Institute of TechnologyShanghai 201418China

This study investigates the mechanism of action of representative molecules of basalt fibers on the healing of water-soaked *** parameters,morphological characteristics,interfacial healing energy,and interfacial healing strength were analyzed using molecular dynamics and macroscopic tests under different time,temperature,and water conditions to evaluate the specific states and critical conditions involved in *** results indicate that basalt-fiber molecules can induce rearrangement and a combination of water-soaked asphalt at the healing *** groups with different bonding states increase the interfacial adsorption capacity of water-soaked *** interaction between basalt fiber molecules and water molecules leads to a"hoop"phenomenon,while aromatics-2 molecules exhibit a"ring band aggregation"*** former reduces the miscibility of water and asphalt molecules,while the latter causes slow diffusion of the ***,a micro-macro dual-scale comparison of interfacial healing strength was conducted at temperatures of 297.15 and 312.15 K to identify the strength transition point and critical temperature of 299.4 K during the self-healing process of basalt-fiber modified water-soaked asphalt.

关键词： water-soaked asphalt basalt-fibers self-healing properties moisture status molecular characterization

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How do Notch Shape and Boundary Conditions Affect the Hydro-Mechanical Behavior of Fractured Geomaterials?Findings via the Darcy-Brinkman-Biot Approach

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Journal of Earth Science 2025年第1期36卷 351-356页

作者： Yi-Xiang Wang Xiao-Pei Guo Ling Xu Shi-Feng Lu Department of Civil engineering School of Human Settlements and Civil EngineeringXi'an Jiaotong UniversityXi'an 710049China China construction Eighth engineering Division Co. Ltd.Southwest BranchChengdu 610041China

0 INTRODUCTION Natural geomaterials,including soils and rocks,are invariably exposed to intricate stress conditions,in addition to water pressure,in various engineering contexts such as foundation treatment,mining,and *** geomaterials frequently contain numerous fractures,which significantly influence hydrological dynamics as water permeates through them,leading to processes like expansion and bifurcation(Shu et al.,2023;Tran and Jha,2021;Lei et al.,2017;Wang et al.,2015).

关键词： bifurcation invar mining

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Life-Cycle Bearing Capacity for Pre-Stressed T-beams Based on Full-Scale Destructive Test

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Structural Durability & Health Monitoring 2025年第1期19卷 145-166页

作者： Yushan Ye Tao Gao Liankun Wang Junjie Ma Yingchun Cai Heng Liu Xiaoge Liu China construction Seventh engineering Division Corp. Ltd.Zhengzhou450004China school of Water Conservancy and Transportation Zhengzhou UniversityZhengzhou450001China

To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete *** on the measurement and ana-lysis of beam deﬂection,strain,and crack development under various loading levels during the research tests,combined with the veriﬁcation coefﬁcient indicators speciﬁed in the codes,the veriﬁcation coefﬁcients of bridges at different stages of damage can be *** results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test *** the complete linear elastic stage,both the deﬂection and bottom strain veriﬁcation coefﬁcients comply with the speciﬁcations,indicating a good structural load-bearing capacity no longer adheres to the code’s *** the non-linear stage,both coefﬁcients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing *** to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s speciﬁed *** strain veriﬁcation coefﬁcient sourced from the compression zone at the bottom of theﬂange is not recommended for assessing the bridge’s load-bearing capacity.

关键词： Pre-stressed T-beams whole process destructive test bearing capacity veriﬁcation coefﬁcient

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Experimental Study and a Modified Model for Temperature-Recovery Stress of Shape Memory Alloy Wire under Different Temperatures

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Structural Durability & Health Monitoring 2025年第2期19卷 347-364页

作者： Zhi-Xiang Wei Wen-Wei Wang Yan-Jie Xue Wu-Tong ZhangQiu-Di Huang Guangxi Lepu Expressway Co. Ltd.Nanning530000China Department of Bridge engineering School of TransportationSoutheast UniversityNanjing211189China Department of Road and Bridge engineering College of Construction EngineeringJilin UniversityChangchun130012China

To investigate the performance of utilizing the shape memory effect of SMA(Shape Memory Alloy)wire to generate recovery stress,this paper performed single heating recovery stress tests and reciprocating heating-cooling recovery stress tests on SMA wire under varying initial strain *** effects of various strains and different energized heating methods on the recovery stress of SMA wires were explored in the single heating *** SMA wire was strained from 2%to 8%initially,and two distinct heating approaches were employed:one using a large current interval for rapid heating and one using a small current interval for slower *** experimental outcomes reveal that during a single heating cycle,the temperature-recovery stress relationship of SMA wire exhibits three distinct stages:the martensite phase stage,the transition stage from martensite to austenite phase,and the austenite phase ***,the choice of heating method does not influence the maximum recovery stress value,and the correlation between initial strain and maximum recovery stress is predominantly ***,conducting the reciprocating temperature rise and fall performance test is important to better simulate the scenario in practical engineering where multiple recovery stress in SMA wires for structural *** this test,two temperature cycling methods were studied:interval rise and fall,as well as direct rise and *** the case of utilizing the interval temperature rise and fall method,it was observed that the recovery stress associated with cooling was significantly higher than that corresponding to heating at the same ***,the recovery stress was lower upon subsequent heating than that measured during the previous heating *** on the experimental results,a prediction model for the temperature-recovery stress relationship has been proposed to simplify numerical *** is hoped that an approximate temperaturerecovery stress curve can be

关键词： SMA wire temperature recovery stress modified model phase transition

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Insight into the bimetallic structure sensibility of catalytic nitrate reduction over Pd-Cu nanocrystals

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Journal of Environmental Sciences 2025年第3期149卷 221-233页

作者： Zhiqiang Zhang Wenhang Li Cailin Zheng Kunyu Chen Heliang Pang Wenxin Shi Jinsuo Lu school of Environmental and Municipal engineering Xi’an University of Architecture and TechnologyXi’an 710055China Key Laboratory of Northwest Water Resources Environment and EcologyMinistry of EducationXian 710055China State Key Laboratory of Urban Water Resource and Environment Harbin Institute of TechnologyHarbin 150090China construction engineering quality and safety supervision center station House and Urban Rural Development Department of AnkangAnkang 725000China College of Urban construction and Environmental engineering Chongqing UniversityChongqing 400044China

Catalytic reduction of nitrate over bimetallic catalysts has emerged as a technology for sustainable treatment of nitrate-containing ***,the structure of bimetallic has been much less investigated for catalyst ***,two main types of Pd-Cu bimetallic nanocrystal structures,heterostructure and intermetallic,were prepared and characterized using high-resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The results show that two individual Pd and Cu nanocrystals with a mixed interface exist in the heterostructure nanocrystals,while Pd and Cu atoms are uniformly distributed across the intermetallic Pd-Cu *** catalytic nitrate reduction experiments were carried out in a semibatch reactor under constant hydrogen *** nitrate conversion rate of the heterostructure Pd-Cu nanocrystals supported onα-Al_(2)O_(3),γ-Al_(2)O_(3),SBA-15,and XC-72R exhibited 3.82-,6.76-,4.28-,2.44-fold enhancements relative to the intermetallic nanocrystals,and the nitrogen and nitrite were the main products for the heterostructure and intermetallic Pd-Cu nanocrystals,*** indicates that the catalytic nitrate reduction over Pd-Cu catalyst is sensitive to the bimetallic structures of the catalysts,and heterostructure bimetallic nanocrystals exhibit better catalytic performances on both the activity and selectivity,which may provide new insights into the design and optimization of catalysts to improve catalytic activity and selectivity for nitrate reduction in water.

关键词： Catalytic nitrate reduction Pd-Cu bimetallic catalyst Heterostructure Intermetallic Activity and selectivity

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Model tests and numerical analysis of emergency treatment of cohesionless soil landslide with quick-setting polyurethane

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Journal of Mountain Science 2025年第1期22卷 110-121页

作者： ZHANG Zhichao TANG Xuefeng HUANG Rufa CAI Zhenjie GAO Anhua Key Laboratory of Geohazard Prevention of Hilly Mountains Ministry of Natural Resources of ChinaFuzhou 350002China Technology Innovation Center for Monitoring and Restoration engineering of Ecological Fragile Zone in Southeast China Ministry of Natural ResourcesFuzhou 350001China Fujian construction Research engineering Consulting Co. Ltd.Fuzhou 350100China Xin Zhongkun construction engineering Co. LTDLongyan 364399China Fujian Jiakang construction engineering Co. LTDLongyan 364199China

Shotcrete is one of the common solutions for shallow *** works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow ***,the solidification time of conventional cement paste is long when shotcrete is used to treat cohesionless soil *** idea of reinforcing slope with polyurethane solidified soil(i.e.,mixture of polyurethane and sand)was *** tests and finite element analysis were carried out to study the effectiveness of the proposed new method on the emergency treatment of cohesionless soil *** loading on the crest of the slope was applied step by step until landslide was triggered so as to test and compare the stability and bearing capacity of slope models with different *** simulated slope displacements were relatively close to the measured results,and the simulated slope deformation characteristics were in good agreement with the observed phenomena,which verifies the accuracy of the numerical *** the condition of surcharge loading on the crest of the slope,the unreinforced slope slid when the surcharge loading exceeded 30 k Pa,which presented a failure mode of local instability and collapse at the shallow layer of slope *** reinforced slope remained stable even when the surcharge loading reached 48 k *** displacement of the reinforced slope was reduced by more than 95%.Overall,this study verifies the effectiveness of polyurethane in the emergency treatment of cohesionless soil landslide and should have broad application prospects in the field of geological disasters concerning the safety of people's live.

关键词： Cohesionless soil landslide Polyurethane Emergency treatment Reinforcement effect Model test Finite element analysis

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The optimal control theory——a scientific approach to fundamentally solving control problems

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Science China(Information Sciences) 2025年第1期68卷 389-391页

作者： Huanshui ZHANG school of Electrical and Automation engineering Shandong University of Science and Technology school of Control Science and engineering Shandong University

The maximum principle has bridged mathematical optimization to optimal control,ushering in significant developments and refinements in optimal control theory,notably during the 1960s with the advent of linear quadratic (LQ)control and linear quadratic estimation (LQE).This progression propelled optimal control theory into further advancements,encompassing stochastic control,robust/H-infinity control,model predictive control (MPC),networked control,and reinforcement learning *** control,established upon a rigorous mathematical foundation,extends static optimization theory to dynamic systems,exhibiting scientific essence,unity,and ***,since its inception,optimal control theory has served as an indispensable core role across all control-related domains,including communication-constrained control in networked systems,consensus control,cooperative control,and reinforcement learning control.

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