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Enhancement of Activated Coal Gangue Waste in Aging Resistance Performance of Asphalt Binder and Influence Mechanism from Interfacial Interaction Ability

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SSRN 2024年

作者： Li, Fan Wang, Linbing Li, Jianfeng Gao, Yang Su, Ningyi Faculty of Civil Engineering and Mechanics Kunming University of Science and Technology Kunming650500 China The Sensing and Perception Lab School of Environmental Civil Agricultural and Mechanical Engineering University of Georgia AthensGA30602 United States Shanxi Key Laboratory of Civil Engineering Disaster Prevention and Control College of Civil Engineering Taiyuan University of Technology Shanxi Taiyuan030024 China

This study conducted thermal activation approach to modify coal gangue (CG) waste from 450 ℃ to 900 ℃ and applied it to enhance aging resistance performance of asphalt binder. The surface morphology, mineral components and size distribution were analyzed via scanning electron microscope (SEM), X-ray diffraction (XRD) and laser granularity techniques. After 10, 20 and 40 h pressure aging vessel (PAV), rheological and chemical aging behaviors of various CG asphalt mastics (CGAM) were characterized by dynamic shear rheometer (DSR) and Fourier Transform infrared spectroscopy (FTIR). The K-B-G* parameter was calculated to measure interfacial interaction ability between asphalt and different fillers, aiming to establish correlation with aging indexes and explore enhancement mechanism of CG waste on aging resistance property of asphalt binder. The multi-scale results show that thermal activation process on CG waste results in particle size decreasing, surface roughness increasing and crystal lattice transferring. These variances contribute to increasing the interaction area of CG particles with asphalt binder. When calcination temperature elevates to 750 ℃, the activated CG exhibits strongest interaction ability with asphalt binder. There is a highly relation between K-B-G* and the aging indexes calculated by fatigue factor, rutting factor and infrared peak intensity at C=O band. This demonstrates that the stronger asphalt-filler interaction ability is, the better aging resistance property of asphalt mastic is. Thermal activation on CG waste has positive influence on enhancing the aging resistance property of corresponding asphalt mastic, and the suggested calcination temperature is 750 ℃. © 2024, The Authors. All rights reserved.

关键词： Particle size

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Experimental study on damping characteristics of elevator traction system

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ADVANCES IN MECHANICAL engineering 2022年第3期14卷

作者： Xu, Peng Peng, Qifeng Jin, Fusong Xia, Fei Xue, Jianghong Yuan, Hong Li, Shanqing Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn 601 Huang Pu Da Dao Guangzhou 51063 Peoples R China China Univ Petr Huadong Coll Pipeline & Civil Engn Qingdao Peoples R China

An elevator traction system is simplified as a damped vibration system. In order to study the damping characteristics of an elevator traction system, this paper tests the vibration characteristics of a car frame on an in-service elevator with a traction ratio of 2:1. The results show that the natural frequency and stiffness of the system decrease with the increase of the elevator load;the attenuation coefficient and damping increase with the increase of the elevator load;Furthermore, the damping of the traction system is related to the initial running direction. Under the same load, the damping value of downward is greater than that of upward. This research establishes the relationship between vibration parameters, load and elevator running direction and provides an approach to solve the problem of quantitative measurement of damping in the process of elevator operation. Results from this study can provide reference for elevator vibration analysis.

关键词： Elevator car frame free vibration damping attenuation coefficient test method

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Deformable micro-continua in which quantum mysteries reside

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Applied Mathematics and Mechanics(English Edition) 2019年第12期40卷 1805-1830页

作者： Heng XIAO Shanghai Institute of Applied Mathematics & Mechanics College of Mechanics and Engineering Science Shanghai University College of Mechanics and Construction Engineering MOE Lab of Disaster Forecast and Control in Engineering Jinan University

Deformable micro-continua of highly localized nature are found to exactly exhibit all quantum effects commonly known for quantum entities at microscopic *** every instant,the spatial configuration of each such micro-continuum is prescribed by four spatial distributions of the mass,the velocity,the internal stress,and the intrinsic angular *** deformability features of such micro-continua in response to all configuration changes are identified with a constitutive equation that specifies how the internal stress responds to the mass density *** is shown that these microcontinua are endowed with the following unique response features:(i)the coupled system of the nonlinear field equations governing their dynamic responses to any given force and torque fields is exactly reducible to a linear dynamic equation governing a complex field variable;(ii)this fundamental dynamic equation and this complex field variable are just the Schrodinger equation and the complex wave function in quantum theory;and,accordingly,(iii)the latter two and all quantum effects known for quantum entities are in a natural and unified manner incorporated as the inherent response features of the micro-continua discovered,thus following objective and deterministic response patterns for quantum entities,in which the physical origins and meanings of the wave function and the Schrodinger equation become self-evident and,in particular,any probabilistic indeterminacy becomes irrelevant.

关键词： quantum entity micro-continuum Hencky strain-energy density nonlinear dynamic equation exact linearization Schrodinger equation deterministic pattern

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Recycled Aggregate Concrete-Filled Steel Tube Columns with Small-Diameter Circular Frp-Confined Sea-Sand Concrete Cores: Conceptual and Experimental Investigations

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SSRN 2023年

作者： Zeng, Lan Wu, Liqi Li, Boqin Fang, Shu Mohamed, Hazem Samih Fang, Zhuangcheng Yuan, Hong MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangdong Guangzhou510632 China Guangdong Architectural Design and Research Institute Co. Ltd. Guangzhou510006 China Guangdong Key Laboratory of Earthquake Engineering & Applied Technique Earthquake Engineering Research & Test Centre Guangzhou University Guangzhou510006 China School of Architectural Engineering Guangzhou Institute of Science and Technology Guangzhou510540 China Fujian Agriculture and Forestry University China

Recycled aggregate concrete (RAC) prepared from waste concrete can achieve the green recycling of resources;however, its inferior material properties hinder its applications. Sea-sand concrete (SSC) can help alleviate the resource shortage of fresh water and river sands but is prone to steel corrosion. To address these challenges, this study developed a new RAC-filled steel tube column with a small-diameter circular fibre-reinforced polymer (FRP)-confined SSC core. This paper presents and discusses the results of the axial compression tests conducted on RAC-filled steel tube columns, with and without small-diameter circular FRP-confined SSC cores. The study investigated the effects of the configuration of the FRP-confined SSC core, diameter-to-thickness ratio of the FRP tubes, compressive strength of RAC and SSC, and cross-sectional shape of the column. The results revealed that using small-diameter circular FRP-confined SSC cores to partially replace RAC was effective in improving the compressive performance of RAC-filled steel tube columns. The increase in the number of FRP tubes, in-filled concrete strength, and confinement stiffness of the steel and FRP tubes contributed to improvements in the structural strength and ductility, resulting in progressive ladder-shaped declines in the post-peak curve. Finally, a reasonable load–capacity model is presented for the proposed columns. © 2023, The Authors. All rights reserved.

关键词： Steel corrosion

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Double-Level Energy Absorption of 3D Printed TPMS Cellular Structures via Wall Thickness Gradient Design

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MATERIALS 2021年第21期14卷 6262-6262页

作者： Zhong, Minting Zhou, Wei Xi, Huifeng Liang, Yingjing Wu, Zhigang Guangzhou Univ Sch Civil Engn Guangzhou 510006 Peoples R China Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

This paper investigates the deformation mechanism and energy absorption behaviour of 316 L triply periodic minimal surface (TPMS) structures with uniform and graded wall thicknesses fabricated by the selective laser melting technique. The uniform P-surface TPMS structure presents a single-level stress plateau for energy absorption and a localized diagonal shear cell failure. A graded strategy was employed to break such localized geometrical deformation to improve the overall energy absorption and to provide a double-level function. Two segments with different wall thicknesses separated by a barrier layer were designed along the compression direction while keeping the same relative density as the uniform structure. The results show that the crushing of the cells of the graded P-surface TPMS structure occurs first within the thin segment and then propagates to the thick segment. The stress-strain response shows apparent double stress plateaus. The stress level and length of each plateau can be adjusted by changing the wall thickness and position of the barrier layer between the two segments. The total energy absorption of the gradient TPMS structure was also found slightly higher than that of the uniform TPMS counterparts. The gradient design of TPMS structures may find applications where the energy absorption requires a double-level feature or a warning function.

关键词： triply periodic minimal surface selective laser melting 316 L stainless steel energy absorption deformation mechanism

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Strengthening Layer with Nano-Twins in Titanium Alloy Induce by Laser Surface Re-Melting: Mechanism of High Strength and Ductility

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SSRN 2022年

作者： Li, Kunmao Liu, Xiaochun Liu, Yujing Wu, Xiang Zhang, Wencai Yang, Junjie Li, Wei Zhou, Shengfeng Institute of Advanced Wear & Corrosion Resistance and Functional Materials MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China Hunan Changsha410004 China Department of Orthopedics First Affiliated Hospital Jinan University Guangzhou510632 China The state Key Laboratory of Mechanical Transmissions Chongqing University Chongqing400044 China

To increase the strength of titanium (Ti) alloys, severe plastic deformation techniques are usually adopted to refine their grain structure, but these methods have long processing cycle, high cost, and easily result in the oxidized of Ti alloys. This work proposes a strategy of laser surface re-melting (LSR) as-cast TC4-1Cu alloy, which can refine its grain into ~63 nm at relatively lower costs and short manufacturing cycle. By forming a thin strengthening layer with a thickness of ~60 μm, the yield strength and tensile strength of the as-cast TC4-1Cu alloy are increased by 28% and 35%, respectively. More importantly, the {10-11} nano-twinned system is activated due to the tensile stress, thereby accommodating plastic strain and producing excellent strain hardening. These improvements in properties are attributed to the surface strengthening layer with nano-twins and the homogenized elemental distribution, which can provide important implications for studying how to address the strength-ductility trade-off in as-cast Ti alloys. © 2022, The Authors. All rights reserved.

关键词： Titanium alloys

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Independent risk evaluation associated with short-term black carbon exposure on mortality in two megacities of Yangtze River Delta, China

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SCIENCE OF THE TOTAL ENVIRONMENT 2023年第1期880卷 163273页

作者： Zhang, Xiaoling Zhang, Yuanrui Xiu, Meng Zhang, Ying Zhu, Bin Ou, Yihan Wang, Shigong Zheng, Canjun Chengdu Univ Informat Technol Sch Atmospher Sci Plateau Atmosphere & Environm Key Lab Sichuan Prov Chengdu 610225 Peoples R China Chengdu Plain Urban Meteorol & Environm Sichuan Pr Chengdu 610225 Peoples R China Nanjing Univ Informat Sci & Technol Collaborat Innovat Ctr Forecast & Evaluat Meteorol Key Lab Meteorol Disaster KLME Minist Educ Nanjing Peoples R China Chinese Ctr Dis Control & Prevent Natl Inst Communicable Dis Control & Prevent Beijing 102206 Peoples R China Chengdu Univ Informat Technol Sch Atmospher Sci Chengdu 610225 Peoples R China

The adverse health effects of PM2.5 have been well demonstrated by many studies. However, as a component of PM2.5, evidence on the mortality risk of black carbon (BC) is still limited. In this study, based on the data of daily mean PM2.5 concentration, BC concentration, meteorological factors, total non-accidental (all-cause) and cardiovascular mortality in Shanghai and Nanjing during 2015-2016, a semi-parameter generalized additive model (GAM) in the time series and the constituent residual approach were employed to explore the exposure-response relationship between BC and human mortality in these two megacities of Yangtze River Delta, China. The main objective was to separate the health effects of BC from total PM2.5, and compare the difference of mortality ER related to BC original concentration and adjusted concentration after controlling PM2.5. Results showed that there were all significantly associated with daily mortality for PM2.5 and BC. The percentage excess risk (ER) increases in all-cause and cardiovascular categories were 1.68 % (95 % s 1.28, 2.08) and 2.16 % (95 % CI: 1.54, 2.79) with 1 mu g/m3 increment in original BC concentration in Shanghai. And the ER in Nanjing was smaller than that in Shanghai. After eliminating PM2.5 confounding effects by a constituent residual approach, the BC residual concentration still had a strong significant ER. The ER for BC residual in Shanghai got an obvious increase, and ER of the cardiovascular mortality for all, females and males increased by 0.55 %, 1.46 % and 0.62 %, respectively, while the ER in Nanjing decreased slightly. It also revealed that females were more sensitive to the health risk associated with short-term BC exposure than males. Our findings provide addi-tional important evidence and ER for mortality related to independent BC exposure. Therefore, BC emission reduction should be paid more attention in air pollution control strategies to reduce BC-related health burdens.

关键词： Black carbon Constituent residual approach Excess risk Exposure-response relationship

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Powder bed fusion manufacturing of beta-type titanium alloys for biomedical implant applications: A review

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JOURNAL OF ALLOYS AND COMPOUNDS 2023年 936卷

作者： Zhang, Lai-Chang Chen, Liang-Yu Zhou, Shengfeng Luo, Zhen Edith Cowan Univ Sch Engn 270 Joondalup Dr Perth WA 6027 Australia Jiangsu Univ Sci & Technol Sch Mat Sci & Technol Zhenjiang 212003 Jiangsu Peoples R China Jinan Univ Inst Adv Wear & Corros Resistant & Funct Mat MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Univ Technol Sydney Sch Mech & Mechatron Engn Ultimo NSW 2007 Australia

Thanks to many fascinating properties, such as high mechanical properties, good corrosion resistance, and excellent biocompatibility, beta-type Ti alloys are frequently employed as biomedical implants. In recent decades, rapidly developed powder bed fusion (PBF) technologies have become new methods for fabricating beta-type Ti alloys. This article reviews the recent advances and insightful perspectives on the feedstock powder characteristics (e.g., pre-alloyed powder and elemental powder mixtures), microstructure, me-chanical properties, and corrosion behavior of PBF-produced beta-type Ti alloys in the forms of bulk solid parts and lattice structures. As reviewed, PBF-produced bulk beta-type Ti alloys exhibit higher strength than their conventional counterparts, accompanying with slight decrease in the maximum deformation strain. The corrosion behavior of PBF-produced bulk beta-type Ti alloys with the identical corresponding chemical compositions is related to their phase constituents in microstructure, which results from the fabrication methods or processing procedures. Additionally, PBF-produced bulk beta-type Ti alloys still have higher elastic moduli than the human bones. Hence, with the assistance of PBF technologies, lattice structures of beta-type Ti alloys with lower and controllable moduli are developed to obtain reduced their elastic moduli. For biomedical implant applications, PBF-produced lattice structures of beta-type Ti alloys with multi-functional coatings may become promising materials in the future. Nevertheless, the investigations on the PBF-produced beta-type Ti alloys for biomedical implant applications are hitherto still in the initial stage. (c) 2022 Elsevier B.V. All rights reserved.

关键词： Powder bed fusion Additive manufacturing Beta-type Ti alloy Biomedical materials Properties

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Emergent Constraint on Projection of the North Pacific Monsoon Trough and Its Implications for Typhoon Activity Using CMIP6 Models

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JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 2024年第5期129卷 e2023JD040471-e2023JD040471页

作者： Gou, Yan Wang, Chao Wu, Yuqin Wu, Liguang Nanjing Univ Informat Sci & Technol Collaborat Innovat Ctr Forecast & Evaluat Meteorol Earth Syst Modeling Ctr Pacific Typhoon Res CtrKey Lab Meteorol Disaster Nanjing Peoples R China China Satellite Maritime Tracking & Control Dept Jiangyin Peoples R China Fudan Univ Dept Atmospher & Ocean Sci Shanghai Peoples R China Fudan Univ Inst Atmospher Sci Shanghai Peoples R China

The North Pacific monsoon trough (NPMT) is an imperative large-scale circulation pattern influencing tropical cyclone (TC) activity in the western North Pacific (WNP), thus its future change has great implications for the WNP TC activity. Here future change in the NPMT and its uncertainty are examined by using 35 climate models from Phase six of Coupled Model Intercomparison Project (CMIP6). Due to the El Nino-like sea surface temperature (SST) pattern, the multi-model ensemble (MME) mean projects an eastward extension of the NPMT in the latter half of the 21st century. However, considerable inter-model uncertainty exists in the projection, which is associated with the diversity in the zonal SST gradient across the tropical Pacific. This diversity in the projected SST is largely rooted in the simulated precipitation biases in the tropical Pacific in the historical experiments of CMIP6 models, which can modulate future Pacific SST distribution through the shortwave-SST feedback. This linkage between biases in historical climate and future climate allows us to constrain the projection by using observational data sets. Emergent constraint using observational precipitation data set reduces the projection uncertainty by 48% and projects an eastward extension of the north Pacific NPMT by 6.2 degrees. This eastward extension of the NPMT indicates an eastward migration of TC genesis location, and elongated TC track and thus strengthened TC intensity, suggesting an increased TC-related disaster for residents near the WNP. Tropical cyclones (TCs) in the western North Pacific (WNP) greatly threaten the residents in the Pacific coastal regions due to the TC-related enormous disasters. How TCs will change in a warmer climate is of great scientific and societal concern. However, current state-of-the-art climate models are still insufficient to resolve TCs. Here we take an alternative way to examine the future change in a large-scale circulation important for TC activity (i.e., No

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Compressive and thermal properties of foamed concrete at high temperature

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JOURNAL OF SUSTAINABLE CEMENT-BASED MATERIALS 2022年第6期11卷 353-369页

作者： Xi, Huifeng Yao, Yiming Sun, Yuanfeng Mobasher, Barzin Liu, Yiping Ma, Hongwei Jinan Univ Coll Mech & Construct Engn Guangzhou Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Xi An Jiao Tong Univ State Key Lab Strength & Vibrat Mech Struct Xian Peoples R China Southeast Univ Minist Educ Engn Res Ctr Safety & Protect Explos & Impact Nanjing Peoples R China Southeast Univ Sch Civil Engn Nanjing Peoples R China Arizona State Univ Sch Sustainable Engn & Built Environm Tempe AZ USA South China Univ Technol Sch Civil Engn & Transportat Guangzhou Peoples R China Dongguan Univ Technol Sch Environm & Civil Engn Dongguan Peoples R China

Foamed concrete is an attractive material for structural use and insulation of buildings, which can replace flammable organic insulating materials on the market. This study investigated the compressive and thermal properties of the plain, fly ash and expanded polystyrene (EPS) foamed concrete ranging widely in density from 180 to 1800 kg/m(3). Furthermore, the compressive strength of the plain foamed concrete was analyzed at four density levels of 180, 325, 450, and 595 kg/m(3) and at four temperatures of room temperature, 300, 600, and 900 degrees C to quantify its fire resistance. The compressive strength of the foamed concrete dramatically declined, and it suffered severe damage when the temperature was higher than 300 degrees C. A constitutive stress-strain model incorporating the compressive strength-density relationship and the temperature effects was also proposed for the plain foamed concrete. The findings may provide new perspectives on the existing design codes for energy efficiency and fire protection.

关键词： Foamed concrete compressive behavior thermal conductivity elevated temperature constitutive relation

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