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Journal of Wuhan University of Technology(Materials science) 2024年第2期39卷 353-363页

作者：杨志强李化建 WEN Jiaxing DONG Haoliang HUANG Fali WANG Zhen YI Zhonglai railway Engineering Research Institute China Academy of Railway Science Corporation LimitedBeijing 100081China State Key Laboratory for Track System of High-Speed railway Beijing 100081China School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China

In order to clarify the fatigue damage evolution of concrete exposed to flexural fatigue loads,ultrasonic pulse velocity(UPV),impact-echo technology and surface electrical resistance(SR) method were *** variable based on the change of velocity of ultrasonic pulse(Du) and impact elastic wave(Di)were defined according to the classical damage *** influences of stress level,loading frequency and concrete strength on damage variable were *** experimental results show that Du and Di both present a three-stages trend for concrete exposed to fatigue *** impact elastic wave is more sensitive to the microstructure damage in stage Ⅲ,the critical damage variable,i e,the damage variable before the final fracture of concrete of Di is slightly higher than that of ***,the evolution of SR of concrete exposed to fatigue loads were analyzed and the relationship between SR and Du,SR and Di of concrete exposed to fatigue loads were *** is found that the SR of concrete was decreased with the increasing fatigue cycles,indicating that surface electrical resistance method can also be applied to describe the damage of ballastless track concrete exposed to fatigue loads.

关键词： ballastless track fatigue damage ultrasonic pulse velocity impact-echo surface electrical resistance

Investigation of cracking mechanism of the first tunnel lining during double-arch tunnel construction

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Underground Space 2024年第1期14卷 1-17页

作者： Yi Sui Xiaohui Cheng Zuozhou Zhao Weibin Ma railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China School of Civil Engineering Tsinghua UniversityBeijing 100084China

To solve the engineering problem of the first tunnel lining cracking caused by the second tunnel construction of double-arch highway tunnels,a research method combining distributed optical-fibre monitoring,inversion analysis and numerical simulation that can reflect lining cracking was *** fibres were laid on opposite sides of the steel arches inside the first tunnel *** optical-fibre monitoring was conducted continuously during the second tunnel *** on the fibre-optic strain profile,the lining cracking was deduced and warned in *** mechanical behaviour of the steel arch was investigated by the inversion analysis,which took into consideration the integrated impact of axial force and flexural moment.A two-dimensional(2D)load-structure method–based numerical model was established,considering the influence of different load distributions in each construction *** total strain rotating crack constitutive model was applied to reflect the cracking behaviour of concrete lining in the simulation,and the model was calibrated and verified in the *** analysis between the simulated strain distribution and the distributed optical-fibre monitoring results was carried *** deformation mode and crack distribution of the lining were *** cracking mechanism was ***,the second tunnel construction led to the loading at the top of the middle partition wall and the release of rock pressure in the first *** these load changes,the secondary lining of the first tunnel cracked on the inner side of the top of the middle partition wall owing to tension,and compression-bending failure occurred near the right arch ***,the influence of the parameters on the lining force was analysed,and a construction optimisation scheme was proposed.

关键词： Double-arch tunnel Cracking mechanism Distributed optical-fibre sensing Inversion analysis Total strain rotating crack model Loadstructure method

Experimental and Numerical Investigation on the Aerodynamic Characteristics of High-Speed Pantographs with Supporting Beam Wind Deflectors

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Fluid Dynamics & Materials Processing 2024年第1期20卷 127-145页

作者： Shiyang Song Tongxin Han Postgraduate Department China Academy of Railway SciencesBeijing100081China Locomotive&Car Research Institute China Academy of Railway Sciences Corporation LimitedBeijing100081China

Aiming to mitigate the aerodynamic lift force imbalance between pantograph strips,which exacerbates wear and affects the current collection performance of the pantograph-catenary system,a study has been conducted to support the beam deflector optimization using a combination of experimental measurements and computational fluid dynamics(CFD)*** results demonstrate that the size,position,and installation orientation of the wind deflectors significantly influence the amount of force *** also indicate that the front strip deflectors should be installed downwards and the rear strip deflectors upwards,thereby forming a“π”***,the lift force compensation provided by the wind deflectors increases with the size of the *** wind compensation strategies,such as control circuits,are also discussed,putting emphasis on the pros and cons of various pantograph types and wind compensation approaches.

关键词： High-speed pantograph aerodynamic lift force supporting beam wind deflectors computational fluid dynamics(CFD)

Experimental study on the compression-shear performance of a new-type circumferential joint of shield tunnel

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Underground Space 2024年第1期14卷 138-155页

作者： Ziyang Zhou Kun Feng Yiteng Liu Bohan Wu Chunfang Lu Gang Lin Chuan He Key Laboratory of Transportation Tunnel Engineering of Ministry of Education Southwest Jiaotong UniversityChengdu 610031China china academy of railway sciences Corporation Limited Beijing 100081China china railway Eryuan Engineering Group Co. Ltd.Chengdu 610031China

To investigate the compression-shear behavior of a new circumferential joint based on the sleeve-straight bolt combination type connection of large-diameter shield tunnels,a series of full-scale joint experiments was carried *** the process of the experiment,more attention was paid to the specimen displacement,bolt stress and joint damage *** the basis of these experiment phenomena,this study discussed the compression-shear bearing process of the new connector,analyzed the damage mode of the joint structure,and finally evaluated the performance of the new *** is found that the bearing process of the joint can be divided into four stages:the transitional stage for overcoming the friction of the concrete,the sleeve bearing stage for the sleeve bearing shear loads alone,the combined bearing stage for bearing shear loads by the connector system,and the structural damage stage for structural instability and *** speaking,affected by connector position and hand hole,the positive compression-shear stiffness of the joint is less than the negative compression-shear stiffness,and the positive shear strength of the joint is greater than the negative shear *** increase of longitudinal axial force will improve the compression-shear performance of the *** relationship between longitudinal axial force and joint stiffness is a logarithmic *** use of new type of connector can effectively improve the compression-shear stiffness of joints under low shear loads,but the application of straight bolts will lose part of the strength performance.

关键词： Shield tunnel New type of connector Shear resistance Full-scale experiment Circumferential joint

Forward to the Special Topic on“Solving Differential Equations with Deep Learning”

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Journal of Systems science & Complexity 2024年第2期37卷 389-390页

作者： YAN Zhenya academy of Mathematics and Systems science Chinese Academy of SciencesBeijing 100190China

The concept of artificial intelligence(AI)was first presented at the Dartmouth SummerResearch Project on AI hosted by McCarthy and Minsky in *** that,the developmentof AI has experienced ups and downs due to some limited conditions including intelligentcomputing techniques,computer and hardware and software^([1,2]).In particular,with the rapidof deep artificial neural networks,machine learning(ML)and deep learning(DL)techniques^([3,4])have been applied in many fields of science and engineering,including machine translation,image recognition,genomics,scientific computing and atmospheric science,etc^([5]).

关键词： has artificial hardware

The Investigation of Data Voting Algorithm for Train Air-Braking System Based on Multi-Classification SVM and ANFIS

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Chinese Journal of Electronics 2024年第1期33卷 274-281页

作者： Juhan WANG Ying GAO Yuan CAO Tao TANG School of Electronics and Information Engineering Beijing Jiaotong University Graduate Department China Academy of Railway Science National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University

The pressure data of the train air braking system is of great significance to accurately evaluate its operation state. In order to overcome the influence of sensor fault on the pressure data of train air braking system, it is necessary to design a set of sensor fault-tolerant voting mechanism to ensure that in the case of a pressure sensor fault, the system can accurately identify and locate the position of the faulty sensor, and estimate the fault data according to other normal data. A fault-tolerant mechanism based on multi-classification support vector machine(SVM) and adaptive network-based fuzzy inference system(ANFIS) is introduced. Multi-classification SVM is used to identify and locate the system fault state, and ANFIS is used to estimate the real data of the fault sensor. After estimation, the system will compare the real data of the fault sensor with the ANFIS estimated data. If it is similar,the system will recognize that there is a false alarm and record it. Then the paper tests the whole mechanism based on the real data. The test shows that the system can identify the fault samples and reduce the occurrence of false alarms.

关键词： Support vector machines Fault diagnosis Pressure sensors Fuzzy logic Fault tolerance Adaptive systems Fault tolerant systems

Preparation of Modified UiO-66 Catalyst and Its Catalytic Performance for NH_(3)-SCR Denitration

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Journal of Wuhan University of Technology(Materials science) 2024年第2期39卷 261-267页

作者：吴彦霞梁海龙 CHEN Yufeng HU Liming WANG Chunpeng Ceramics science Institute China Building Materials AcademyBeijing 100002China

Zirconium-based metal-organic framework UiO-66 was successfully prepared by solvothermal method,and UiO-66 was modified by adding regulators such as formic acid,acetic acid,and hydrochloric *** NH_(3)-SCR reactivity of the samples was evaluated by the denitration activity evaluation system,and the UiO-66 and the regulator-modified UiO-66 were characterized by XRD,SEM,BET,FTIR,TG,NH_(3)-TPD,etc.,the effects of regulator types on the structure and properties of UiO-66 were *** experimental results show that,after adding the modifier,the morphology of UiO-66 changes from irregular quadrilateral with serious agglomeration to particles with regular crystal shape and good dispersibility,and the crystal morphology of the catalyst is *** addition,after adding the modifier,UiO-66 has a larger specific surface area and stronger surface acidity,which optimizes the catalytic performance of *** catalytic performance test results of NH_(3)-SCR show that the low-temperature activity of UiO-66 is poor,and it only shows a certain catalytic activity at higher *** catalytic activity of UiO-66 was significantly improved after adding the *** them,the UiO-66-HCl modified with hydrochloric acid had the best catalytic activity,and the denitration rate reached 70%when the denitration temperature was 380℃.

关键词： UiO-66 catalyst catalytic denitration NH_(3)-SCR modified

Dynamic Scene Graph Generation of Point Clouds with Structural Representation Learning

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Tsinghua science and Technology 2024年第1期29卷 232-243页

作者： Chao Qi Jianqin Yin Zhicheng Zhang Jin Tang School of Artificial Intelligence Beijing University of Posts and TelecommunicationsBeijing 100876China Standard and Metrology Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China

Scene graphs of point clouds help to understand object-level relationships in the 3D *** graph generation methods work on 2D structured data,which cannot be used for the 3D unstructured point cloud *** point-cloud-based methods generate the scene graph with an additional graph structure that needs labor-intensive manual *** address these problems,we explore a method to convert the point clouds into structured data and generate graphs without given ***,we cluster points with similar augmented features into groups and establish their relationships,resulting in an initial structural representation of the point ***,we propose a Dynamic Graph Generation Network(DGGN)to judge the semantic labels of targets of different *** dynamically splits and merges point groups,resulting in a scene graph with high *** show that our methods outperform other baseline *** output reliable graphs describing the object-level relationships without additional manual labeled data.

关键词： scene graph generation structural representation point cloud

Study on thermal decomposition kinetics of azobenzene-4,4′-dicarboxylic acid by using compensation parameter method and nonlinear fitting evaluation

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Chinese Journal of Chemical Engineering 2024年第6期70卷 269-279页

作者： Shuyi Shen Song Guo Sining Chen Jinhua Zhao Nanjing University of science&Technology Nanjing 210094China china academy of Safety science and Technology Beijing 100012China

Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent *** large quantities put into application in the future,the thermal stability of this substance during storage,transportation,and use will become quite ***,in this work,the thermal decomposition behavior,thermal decomposition kinetics,and thermal hazard of ADCA were *** were conducted by using a SENSYS evo DSC device.A combination of differential iso-conversion method,compensation parameter method,and nonlinear fitting evaluation were also used to analyze thermal kinetics and mechanism of ADCA *** results show that when conversion rate α increases,the activation energies of ADCA's first and main decomposition peaks *** amount of heat released during decomposition varies between 182.46 and 231.16 J·g^(-1).The proposed kinetic equation is based on the Avrami-Erofeev model,which is consistent with the decomposition *** the Frank-Kamenetskii model,a calculated self-accelerating decomposition temperature of 287.0℃is obtained.

关键词： Azobenzene-4,4′-dicarboxylic acid Thermal decomposition behavior Kinetic mechanism Thermal hazard evaluation Compensation parameter effect

L vector spaces and L fields

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science china Mathematics 2024年第10期67卷 2195-2216页

作者： Yinhe Peng Liuzhen Wu academy of Mathematics and Systems science Chinese Academy of SciencesBeijing 100190China

We construct in ZFC(the Zermelo-Fraenkel system with choice) an L topological vector space—a topological vector space that is an L space—and an L field—a topological field that is an L space. This generalizes earli... 详细信息

关键词： minimal walk topological vector space topological eld L space L vector space L eld