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Face stability analysis of large shield-driven tunnel in rock-soil interface composite formations

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Underground Space 2022年第6期7卷 1021-1035页

作者： Xiaobin Ding Kang Li yuxuan xie Shuzhuo Liu School of Civil Engineering and Transportation South China University of TechnologyGuangzhou 510641China Guangdong Provincial Key Laboratory of Modern Civil Engineering Technology South China Institute of Geotechnical EngineeringGuangzhou 510650China

A new 3D log-spiral model(LS-M model)is proposed to determine the minimal support pressure on the tunnel face of a large shielddriven tunnel in rock-soil interface(RSI)composite *** the proposed LS-M model,we define the RSI angle ω and use a new approach to calculate the equivalent tunnel face area,which provides a collapse zone with more realistic geometry than the traditional wedge *** it has acceptable accuracy with simpler implementation than limit equilibrium *** with previous studies and 3D numerical analysis,it indicates that:(i)the LS-M results agree well with others in full-soil formations on the variation patterns of minimum support pressure and stability coefficients N_(c) and N_(γ);(ii)the critical RSI angle ω_(cr),which is predominantly influenced by soil cohesion,increases with the soil property values;(iii)the limit support pressure starts to increase with ω only when ω>ω_(cr);(iv)the peak support pressure occurs at lower C/D with a lower ω;(v)ω can only affect stability coefficients N_(c) and N_(γ) when ω and the friction angle are relatively small,while N_(s) is substantially influenced by RSI angle ω.

关键词： Tunnel Stability Limit support pressure RSI composite formations 3D failure mechanism

Chinese Spirits Identification Model Based on Mid-Infrared Spectrum

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Computers, Materials & Continua 2020年第9期64卷 1869-1883页

作者： Wu Zeng Zhanxiong Huo yuxuan xie Yingxiang Jiang Kun Hu School of Electrical and Electronic Engineering Wuhan Polytechnic UniversityWuhan430000China Gina Cody School of Engineering and Computer Science Concordia UniversityMontrealH3G 1M8Canada

Applying computer technology to the field of food safety,and how to identify liquor quickly and accurately,is of vital importance and has become a research *** this paper,sparse principal component analysis(SPCA)was applied to seek sparse factors of the mid-infrared(MIR)spectra of five famous vintage year Chinese *** results showed while meeting the maximum explained variance,23 sparse principal components(PCs)were selected as features in a support vector machine(SVM)model,which obtained a 97%classification *** comparison principal component analysis(PCA)selected 10 PCs as features but only achieved an 83%classification *** both approaches were better than a direct SVM approach based on the classification results(64%classification accuracy),they also demonstrated the importance of extracting sparse PCs,which captured most important *** combination of computer technology SPCA and MIR provides a new and convenient method for liquor identification in food safety.

关键词： Mid-infrared spectra Chinese spirits SPCA SVM liquor identification

Microwave Absorption and Mechanical Properties of Short-cutted Carbon Fiber/glass Fiber Hybrid Veil Reinforced Epoxy Composites

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Journal of Wuhan University of Technology(Materials Science) 2023年第1期38卷 248-254页

作者：陈威 ZHEN Bowen xie yuxuan 贺行洋 SU Ying WANG Jun WU Yan School of Civil Engineering Architecture and EnvironmentHubei University of TechnologyWuhan 430068China Building Waterproof Engineering and Technology Research Center of Hubei Province Hubei University of TechnologyWuhan 430068China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Institute of Advanced Material Manufacturing Equipment and Technology Wuhan University of TechnologyWuhan 430070China Hubei Standardization and Quality Institute Wuhan 430061China

This work aims at investigating the microwave absorption and mechanical properties of short-cutted carbon fiber/glass fiber hybrid veil reinforced epoxy *** short-cutted carbon fibers(CFs)/glass fibers(GFs)hybrid veil were prepared by papermaking technology,and composites liquid molding was employed to manufacture CFs/GFs hybrid epoxy *** microstructure,microwave absorbing properties and mechanical properties of the hybrid epoxy composites were studied by using SEM,vector network analyzer and universal material testing,*** reflection coefficient of the composites were calculated by the measured complex permittivity and permeability in the X-band(8.2-12.4 GHz)*** optimum microwave absorption properties can be obtained when the content of CFs in the hybrid veil is 6 wt%and the thickness of the composites is 2 mm,the minimum reflection coefficient of-31.8 dB and the effective absorption bandwidth is 2.1 GHz,which is ascribed to benefitting impedance matching characteristic and dielectric loss of the carbon *** the tensile strength and modulus can achieve 104.0 and 2.98GPa,demonstrating that the CFs/GFs hybrid epoxy composites can be a promising candidate of microwave absorbing materials with high mechanical properties.

关键词： microwave absorption fiber reinforced composites papermaking carbon fiber

Shape Memory Polymer Composite Booms with Applications in Reel-Type Solar Arrays

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Chinese Journal of Mechanical Engineering 2023年第3期36卷 326-338页

作者： Hong Xiao Sijie Wu Dongdong xie Hongwei Guo Li Ma yuxuan Wei Rongqiang Liu State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150006China Yinhe Hangtian Internet Technology Co. Ltd.Beijing 100192China China Academy of Space Technology Beijing 100098China

Solar arrays are the primary energy source for *** traditional rigid solar arrays improve power supply,the quality increases ***,it is difficult to satisfy the requirements of high-power and low-cost space *** this study,a shape-memory polymer composite(SMPC)boom was designed,fabricated,and characterized for flexible reel-type solar *** SMPC boom was fabricated from a smart material,a shape-memory polymer composite,whose mechanical properties were ***,a mathematical model of the bending stiffness of the SMPC boom was developed,and the bending and buckling behaviors of the boom were further analyzed using the ABAQUS *** SMPC boom was fabricated to demonstrate its shape memory characteristics,and the driving force of the booms with varying geometric parameters was *** also designed and manufactured a reel-type solar array based on an SMPC boom and verified its self-deployment *** results indicated that the SMPC boom can be used as a deployable unit to roll out flexible solar arrays.

关键词： Shape memory polymer composite Reel-type solar array Deployable boom Bending behavior

An Improved Approach to the Performance of Remote Photoplethysmography

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Computers, Materials & Continua 2022年第11期73卷 2773-2783页

作者： Yi Sheng Wu Zeng Qiuyu Hu Weihua Ou yuxuan xie Jie Li School of Electrical and Electronic Engineering Wuhan Polytechnic UniversityWuhan430000China School of Electronic and Information Engineering Guizhou Normal UniversityGuizhou550000China Gina Cody School of Engineering and Computer Science Concordia UniversityW.MontrealQuebecH3G1M8Canada

Heart rate is an important metric for determining physical and mental *** recent years,remote photoplethysmography(rPPG)has been widely used in characterizing physiological signals in human ***,research on non-contact detection of heart rate mainly focuses on the capture and separation of spectral signals from video ***,this method is very sensitive to the movement of the test subject and light intensity variation,and this results in motion artifacts which presents challenges in extracting accurate physiological signals such as heart *** this paper,an improved method for rPPG signal preprocessing is *** on the well known red green blue(RGB)color space,we segmented skin tone in different color spaces and extracted rPPG signals,after which we use a skin segmentation training model based on the luminance component,the blue-difference chroma components,and red-difference chroma components(YCbCr),as well as hue saturation intensity(HSI)color *** the experimental verification section,we compare the robustness of the signal on different color *** summary,we are experimentally verifying a better image pre-processing method based on real-time rPPG,which results in more precise measurements through the comparative analysis of skin segmentation and signal quality.

关键词： Remote photoplethysmography skin segmentation heart rate

Achieving highest Young’s modulus in Al-Li by tracing the size and bonding evolution of Li-rich precipitates

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Journal of Materials Science & Technology 2023年第14期145卷 125-135页

作者： Chengpeng Xue yuxuan Zhang Shuo Wang Guangyuan Tian Xinghai Yang Yubin Ke Zhenhua xie Junsheng Wang School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China China Spallation Neutron Source Dongguan BranchInstitute of High Energy PhysicsChinese Academy of SciencesDongguan 523803China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China

For decades,it has been well accepted that every 1 wt.%Li addition to Al will reduce Al alloy’s density by 3%and increase its Young’s modulus by 6%.However,the fundamental mechanism of modulus improve-ments stays controversial though all studies agreed that the contribution of such a substantial boosting comes from Li-rich clusters either in solid solution or *** this study,we experimentally produce nano-sized Li-rich clusters by non-equilibrium solidification using centrifugal casting and trace their evolutions as a function of subsequent heat ***-resolution transmission electron mi-croscopy(HRTEM)reveals a further decrease in the lattice constants of Li-rich regions from the as-cast(0.406 nm),solid solution(0.405 nm)to the aged state(0.401 nm),while Young’s modulus of the Al-Li al-loy reaches 89.16 ***-angle neutron scattering(SANS)experiments and first-principle calculations based on density functional theory have shown both the bond strength around precipitates and the size of those Li-rich region dominate Young’s *** the beginning,it is volumetric compression due to Li addition that increases modulus,tightening the Al-Al potential *** the end,it is the Al-Al and Al-Li valence bonds in Al 3 Li at large size and high-volume fraction which increase its second derivative of internal energy and thus Young’s modulus.

关键词： Al-Li alloy Young’s modulus SANS HRTEM DFT Precipitate kinetics

Simple construction of the α-MnO2@ZIF-8 nanomaterial with highly enhanced U(Ⅵ) adsorption performance and assessed removal mechanism

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Progress in Natural Science:Materials International 2023年第4期33卷 508-517页

作者： Siyi Wang yuxuan Bai Zhixiong Zhang Chengde xie Wenhui Song Chen Wang Zhuoyu Ji Jianjun Wang North China Electric Power University MOE Key Laboratory of Resources and Environmental Systems Optimization College of Environmental Science and Engineering

In this study, the one-dimensional nanomaterial α-MnO2@ZIF-8 was satisfactorily fabricated using a simple hydrothermal method by modifying ZIF-8 on α-MnO2nanowires for high-performance extraction of U(Ⅵ) out of water solution. The experimental data indicated that the adsorption of U(Ⅵ) on α-MnO2@ZIF-8 was intensely dependent on solution pH but not on ionic strength. The maximum adsorption of U(Ⅵ) on α-MnO2@ZIF-8 at pH= 5.0 and T = 298 K was 802.36 mg/g, substantially higher than the adsorption on α-MnO2(22.32 mg/g) or ZIF-8(551.31 mg/g) under the same conditions, indicating that the performance of the modified α-MnO2was greatly enhanced. Attaining adsorption equilibrium within 45 min, the analytical kinetic process of α-MnO2@ZIF-8 indicated that its adsorption on U(Ⅵ) was monolayer chemisorption. The adsorption experiments and XPS analyzed the possible adsorption mechanism of U(Ⅵ) in the reaction with α-MnO2@ZIF-8 during the adsorption process, namely intra-sphere surface complexation, chemisorption and electrostatic interaction. The simple preparation and high removal efficiency of α-MnO2@ZIF-8 indicated that this adsorbent had good prospects for application in wastewater.

关键词： α-MnO_2@ZIF-8 Adsorption Uranium Mechanism

Numerical study of effect of post injection coupled with EGR on combustion and emission performances of CRDI engine fueled with biodiesel-ethanol blends

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第6期10卷 1174-1186页

作者： Limin Geng Hongliang Xiao yuxuan Cui Nan Gao Qi Li Hao Chen Yuantao xie Key Laboratory of Shaanxi Province for Development and Application of New Transportation Energy Chang'an UniversityXian 710064China School of Energy and Electrical Engineering Chang'an UniversityXian 710064China Geely Automobile Research Institute(Ningbo)Co. Ltd.Ningbo 311228China

Energy shortage and environmental pollution are becoming more serious,biodiesel is regarded as the most promising alternative fuel for diesel engines due to its environmentally friendly and renewable *** this study,the biodiesel-ethanol blends were used in a diesel engine,and the purpose of the study was to simultaneously control the NOx and soot emissions of the diesel engine by adjusting the injection strategy and EGR rate.A turbocharged,six-cylinder,common rail direct injection(CRDI)engine model was established using *** effects of the main-post injection strategy and post injection coupled with exhaust gas recirculation(EGR)on combustion and emission characteristics were investigated at a maximum torque speed and a medium *** results show that when the main-post injection strategy is employed,the combustion duration of the main injection is shortened with an increase in the main-post injection interval(MPI).When the MPI increased to more than 18℃A,the heat release of post injection could be observed clearly from the curve of the heat release rate,NOx emissions decreased by 5.70%and 7.12%,respectively,and soot emissions decreased by 25.56%and 30.20%,***,with the increasing post injection quantity,the combustion duration of the main injection shortened,and the peak heat release rate(PHRR)of the post injection *** the fuel quantity for the post injection increased from 2 to 6 mg,NOx emissions decreased from 2.33%to 9.80%,and soot emissions decreased from 16.10%to 34.97%.The effect of post injection quantity on emissions was more significant than that of the *** addition,with increasing EGR rate,the ignition delay is prolonged,the peak cylinder pressure,PHRR,peak combustion temperature and NOx emissions decrease,whereas soot emissions increase ***-post injection can improve the NO-soot trade-off,the optimal EGR rate is 22.86%under a post injection quantity of 4 mg and a MPI of 22℃A.

关键词： Post injection Exhaust gas recirculation Combustion characteristics Exhaust emissions Biodiesel-ethanol blends

An alternative approach to improve the compatibility of PCE in cement paste blend with coal gangue powder

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Waste Disposal and Sustainable Energy 2024年第1期6卷 139-150页

作者： Zonglin xie yuxuan Li Dahui Sun Yi Tian Jinyuan Hu Qiang Yuan Zheng Chen School of Civil Engineering Central South UniversityChangshaChina China Railway NO.9 Group CO. LTDShenyangChina National Engineering Research Center for High-Speed Railway Construction Technology ChangshaChina Guangxi Key Laboratory of Disaster Prevention and Engineering Safety Guangxi UniversityNanningChina

Coal gangue(CG)is an environmental waste that faces an urgent demand for disposal in *** utilization of CG in construction materials has broad application prospects and gained increasing ***,the poor compatibility of polycarboxylate superplasticizer(PCE)with CG powder hinders its efficiency in a wide range of ***,this paper attempts to improve the compatibility of PCE with CG powder in cement paste based on the regulation of aggregation and the adsorption behavior of *** light scattering(DLS)and fluorescence spectroscopy tests were carried out to understand the improved *** results indicated that the addition of CG powder increases the ionic strengths of the cement liquid phase,which makes PCE tend to aggregate at a lower concentration compared with no CG powder ***(CH_(3)COO)_(2)Cu is beneficial for enhancing the workability of cement paste by reducing PCE aggregation while maintaining the compressive strength of cement ***,(CH_(3)COO)_(2)Cu extra addition can be regarded as an effective and sustainable way to improve the workability of cement paste with CG powder.

关键词： Coal gangue powder Polycarboxylate superplasticizer Compatibility Aggregation