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Deep learning for P-wave arrival picking in earthquake early warning

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Earthquake Engineering and Engineering Vibration 2021年第2期20卷 391-402页

作者： Wang Yanwei Li Xiaojun Wang Zifa shi jianping Bao Enhe College of Architecture and Civil Engineering Beijing University of TechnologyBeijing 100022China Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering Guilin University of TechnologyGuilin 541004China College of Architecture and Civil Engineering Henan UniversityKaifeng 475004China Institute of Engineering Mechanics China Earthquake AdministrationHarbin 150080China China Academy of Railway Sciences China Railway CorporationBeijing 100081China

Fast and accurate P-wave arrival picking significantly affects the performance of earthquake early warning(EEW)*** P-wave picking algorithms used in EEW have encountered problems of falsely picking up noise,missing P-waves and inaccurate P-wave arrival *** address these issues,an automatic algorithm based on the convolution neural network(DPick)was developed,and trained with a moderate number of data sets of 17,717 *** to the widely used approach of the short-term average/long-term average of signal characteristic function(STA/LTA),DPick is 1.6 times less likely to detect noise as a P-wave,and 76 times less likely to miss *** terms of estimating P-wave arrival time,when the detection task is completed within 1 s,DPick′s detection occurrence is 7.4 times that of STA/LTA in the 0.05 s error band,and 1.6 times when the error band is 0.10 *** verified that the proposed method has the potential for wide applications in EEW.

关键词： P-wave arrival convolution neural network deep learning earthquake early warning

Microscopic insights into the catalytic mechanisms of monolayer MoS2 and its heterostructures in hydrogen evolution reaction

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Nano Research 2019年第9期12卷 2140-2149页

作者： Min Hong jianping shi Yahuan Huan Qin Xie Yanfeng Zhang Department of Materials Science and Engineering College of EngineeringPeking UniversityBeijing 100871China Center for Nanochemistry (CNC) Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

Exploring high-efficient catalysts for hydrogen evolution reaction(HER)has become very urgeht for resolving the energy related ***,two-dimensional layered MoS2 and its heterostructures with graphene or other traditional photocatalysts have presented great potentials for electrocatalytic and photocatalytic HER ***-site investigations of the atomic-scale structures and local electronic properties of the catalytically active sites are the key points for understanding the internal mechanisms,which however are hard to be achievec from the practical ***,this review focuses on the recent progresses on the on-site scanning tunneling microscopy/spectroscopy investigations of the atomic structures and electronic properties of the ultrahigh-vacuum deposited and chemical vapor deposition(CVD)synthesized monolayer MoS2 and MoSz/graphene vertical stacks on the electrodes of Au(111)and Au *** correlations between the respective HER activities,edge types and edge electronic states are comparatively ***,this review also introduces thephotocatalytic HER applications of CVD-grown MoS2/WS2 and WS/MoS2 vertical stacks on Au foils,mainly considering of their type-ll *** and the novel interlayer charge transfer ***,future research directions are also proposed for in-depth understanding of the catalytic mechanism,as well as for exploring more efficient HER catalysts.

关键词： M0S2 seanning tunneling microscopy/spectroscopy hydrogen evolution reaction metallic edge states vertical stacks

Research about the Effect of Ultrasonic Impact on the Fatigue Properties of Cruciform Joints of 16MnR Steel

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稀有金属材料与工程 2012年第S1期41卷 283-286页

作者： He Bolin Yu Yingxia Liu Jing Zhang Xiaodong shi jianping E China Jiaotong Univ Minist Educ Conveyance & Equipment Key Lab Nanchang 330013 Peoples R China China Acad Railway Sci Beijing 100081 Peoples R China

Surface impact treatment was carried out on the cruciform joint weldment of 16MnR steel by using the HJ-II-type ultrasonic impact *** ultrasonic impact current is 1.2 A,the impact amplitude is 30?m and ultrasonic impacting time is 30 and 60 min,*** experiments were carried out for both treated specimen and un-treated specimen by using EHF-EM200K2-070-1A fatigue testing *** fatigue fractures were observed with the scanning electron microscope of 6360LA type and the microstructure of ultrasonic impact treating surface layer was analyzed by using high resolution transmission electron microscope of JEM-2100 *** experimental results show that the microstructure of ultrasonic impact surface layer has been successfully *** fatigue life of welded cruciform joints of 16MnR steel can be significantly improved through the ultrasonic impact *** main reasons are that the ultrasonic impact treating can reduces the stress concentration in the weld toe,decrease the tensile stress,and even change to compressive stress in the weldment,the grain size in the welded joint can be *** longer the impact time,the greater increasing range of fatigue life will *** to the sample without treatment,its fatigue life was increased 210.37%,362.48%,respectively,when the impact time was 30,60 min,respectively.

关键词： 16MnR steel fatigue strength ultrasonic impact cruciform joint fracture

GATE simulation based feasibility studies of in-beam PET monitoring in ^(12)C beam cancer therapy

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Nuclear Science and Techniques 2010年第5期21卷 275-280页

作者： WU Jing LIU Yaqiang MA Tianyu WEI Qingyang WANG shi CHENG jianping Key Laboratory of Particle & Radiation Imaging Ministry of Education Department of Engineering Physics Tsinghua University Beijing 100084 China

In comparison with conventional radiotherapy techniques,12C beam therapy has its significant advantage in cancer treatment because the radiation dose are mostly concentrated near the Bragg peak region and damage to normal tissues along the beam path is thus greatly ***-beam PET provides a way to monitor dose distribution inside human body since several kinds of positron-emitting nuclei are produced through the interaction between 12C beam and body *** this work,we study the quantitative relationship between the spatial location of the Bragg peak and the spatial distribution of positrons produced by positron-emitting *** Carlo package GATE is used to simulate the interactions between the incident 12C beam of different energies(337.5,270.0 and 195.0 MeV/u) and various target matters(water,muscle and spine bone).Several data post-processing operations are performed on the simulated positron-emitting nuclei distribution data to mimic the impacts of positron generation and finite spatial resolution of a typical PET imaging *** results are compared to published experimental data for *** all the simulation cases,we find that 10C and 11C are two dominant positron-emitting nuclei,and there exists a significant correlation between the spatial distributions of deposited energy and ***,we conclude that it is possible to determine the location of Bragg peak with 1 mm accuracy using current PET imaging systems by detecting the falling edge of the positron distribution map in depth direction.

关键词：放射治疗癌症治疗模拟聚酯正电子发射 Bragg峰监测辐射剂量

Improving the device performances of two-dimensional semiconducting transition metal dichalcogenides: Three strategies

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Frontiers of physics 2022年第6期17卷 35-50页

作者： Mo Cheng Junbo Yang Xiaohui Li Hui Li Ruofan Du jianping shi Jun He The Institute for Advanced Studies Wuhan UniversityWuhan 430072China Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education School of Physics and TechnologyWuhan UniversityWuhan 430072China

Two-dimensional(2D)semiconductors are emerging as promising candidates for the next-generation *** a type of unique channel materials,2D semiconducting transition metal dichalcogenides(TMDCs),such as MoS2 and WS2,exhibit great potential for the state-of-the-art fieldeffect transistors owing to their atomically thin thicknesses,dangling-band free surfaces,and abundant band *** so,the device performances of 2D semiconducting TMDCs are still failing to reach the theoretical values so far,which is attributed to the intrinsic defects,excessive doping,and daunting contacts between electrodes and *** this article,we review the up-to-date three strategies for improving the device performances of 2D semiconducting TMDCs:(i)the controllable synthesis of wafer-scale 2D semiconducting TMDCs single crystals to reduce the evolution of grain boundaries,(ii)the ingenious doping of 2D semiconducting TMDCs to modulate the band structures and suppress the impurity scatterings,and(iii)the optimization design of interfacial contacts between electrodes and channels to reduce the Schottky barrier heights and contact *** the end,the challenges regarding the improvement of device performances of 2D semiconducting TMDCs are highlighted,and the further research directions are also *** believe that this review is comprehensive and insightful for downscaling the electronic devices and extending the Moore’s law.

关键词： 2D semiconductor transition metal dichalcogenides waferscale single crystal ingenious doping interfacial contact device performance

Controlled Syntheses and Multifunctional Applications of Two-Dimensional Metallic Transition Metal Dichalcogenides

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Accounts of Materials Research 2021年第9期2卷 751-763页

作者： Peng Wang Yahuan Huan Pengfei Yang Mo Cheng jianping shi Yanfeng Zhang The Institute for Advanced Studies Wuhan UniversityWuhan 430072China School of Materials Science and Engineering Peking UniversityBeijing 100871China

CONSPECTUS:Among two-dimensional(2D)layered materials,metallic transition metal dichalcogenides(MTMDCs)are emerging as promising candidates in many application aspects(e.g.,electronics,spintronics,and energy related fields,etc.)in view of their ultrahigh electronic conductivities,newfangled room-temperature ferromagnetism(e.g.,VSe_(2),VTe_(2)),and excellent catalytic ***,2D TaX_(2) and VX_(2)(X=S,Se,Te)materials stand in a vital place on account of their exotic physical and chemical ***,the controlled synthesis of such materials is the premise for exploring the aforementioned properties and *** the reported preparation methods,chemical vapor deposition(CVD)is proven to be a promising approach in view of its scalability,simple operation,low cost,*** method has been employed to synthesize various 2D layered materials and heterostructures in a well-controlled ***,in view of the complicated growth mechanism and process,the CVD growth of ultrathin TaX_(2) and VX_(2) nanosheets/films remains extremely *** addition,the application explorations of 2D TaX_(2) and VX_(2) in the energy related fields and electronic devices are still in the primary *** this Account,we review the up-to-date advances regarding the CVD syntheses of 2D TaX_(2) and VX_(2)(e.g.,TaS_(2),TaSe_(2),VS_(2),VSe_(2),and VTe_(2),etc.)and air-stable MTMDCs(e.g.,PtSe2,NiTe2),as well as their multifunctional applications in the energy related fields and electronic ***,the CVD growth of TaX_(2) and VX_(2) nanosheets/films with tunable thicknesses/domain sizes and the MTMDCs/semiconducting TMDCs vertical heterostructures are systematically ***,the application explorations of CVD-synthesized 2D TaX_(2) and VX_(2) as high-performance electrode materials in electrocatalytic hydrogen evolution reaction(HER)and electronic devices are introduced,***,the CVD syntheses of 2D MTMDCs with robust envir

关键词： properties Transition mentioned

Transformation of monolayer MoS2 into multiphasic MoTe2： Chalcogen atom-exchange synthesis route

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Nano Research 2017年第8期10卷 2761-2771页

作者： Qiyi Fang Zhepeng Zhang Qingqing Ji Siya Zhu Yue Gong Yu Zhang jianping shi Xiebo Zhou Lin Gu Qian Wang Yanfeng Zhang Department of Materials Science and Engineering College of Engineering Peking University Beijing 100871 China Center for Nanochemistry (CNC) Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Academy for Advanced lnterdisciplinary Studies Peking University Beijing 100871 China Center for Applied Physics and Technology Peking University Beijing 100871 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Collaborative Innovation Center of Quantum Matter Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100190 China

Molybdenum ditelluride （MoTe2）, which is an important transition-metal dichalcogenide, has attracted considerable interest owing to its unique properties, such as its small bandgap and large Seebeck coefficient. However, the batch production of monolayer MoTe2 has been rarely reported. In this study, we demonstrate the synthesis of large-domain （edge length exceeding 30 μm）, monolayer MoTe2 from chemical vapor deposition-grown monolayer MoS2 using a chalcogen atom-exchange synthesis route. An in-depth investigation of the tellurization process reveals that the substitution of S atoms by Te is prevalently initiated at the edges and grain boundaries of the monolayer MoS2, which differs from the homogeneous selenization of MoS2 flakes with the formation of alloyed Mo-S-Se hybrids. Moreover, we detect a large compressive strain （approximately -10%） in the transformed MoTe2 lattice, which possibly drives the phase transition from 2H to 1T＇ at the reaction temperature of 500 ℃. This phase change is substantiated by experimental facts and first-principles calculations. This work introduces a novel route for the templated synthesis of two-dimensional layered materials through atom substitutional chemistry and provides a new pathway for engineering the strain and thus the intriguing physics and chemistry.

关键词： transition-metal dichacogenide MoTe2 atom exchange multiphase phase transformation

Quasi-freestanding, striped WS2 monolayer with an invariable band gap on Au（001）

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Nano Research 2017年第11期10卷 3875-3884页

作者： Min Hong Xiebo Zhou jianping shi Yue Qi Zhepeng Zhang Qiyi Fang Yaguang Guo Yajuan Sun Zhongfan Liu Yuanchang Li Qian Wang Yanfeng Zhang Department of Materials Science and Engineering College of Engineering Peking University Beijing 100871 China Center for Nanochemistry(CNC) Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Academy for Advanced Interdisciplinary Studies Peking University Beijing 100871 China State Key Laboratory of Coal-based Low-carbon Energy ENN Group Co. Ltd. Langfang 065001 China National Center for Nanoscience and Technology Chinese Academy of Sciences Beijing 100190 China Center for Applied Physics and Technology Peking University Beijing 100871 China

Revealing the structural/electronic features and interfacial interactions of monolayer MoS2 and WS2 on metals is essential to evaluating the performance of related *** this study,we focused on the atomic-scale features of monolayer WS2 on Au（001） synthesized via chemical vapor *** tunneling microscopy and spectroscopy reveal that the WS2/Au（001） system exhibits a striped superstructure similar to that of MoS2/Au（001） but weaker interfacial interactions,as evidenced by experimental and theoretical ***,the WS2/Au（001） band gap exhibits a relatively intrinsic value of ～ 2.0 ***,the band gap can gradually decrease to ～ 1.5 eV when the sample annealing temperature increases from ～370 to 720 ℃.In addition,the doping level （or Fermi energy） of monolayer WS2/Au（001） varies little over the valley and ridge regions of the striped patterns because of the homogenous distributions of point defects introduced by ***,this work provides an in-depth investigation into the interfacial interactions and electronic properties of monolayer MX2 on metal substrates.

关键词： WS2 Au(001) striped superstructure interfacial interaction STM/STS

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高速铁路地震预警系统事件确认方法

中国铁道科学 2021年第5期42卷 174-182页

作者：史建平中国铁道科学研究院集团有限公司铁道科学技术研究发展中心北京100081

针对我国高速铁路地震预警系统因非地震事件干扰而产生的误报,基于地震波在2个台站之间的幅值衰减关系,提出1种高速铁路地震预警系统事件确认方法,既可以及时解除预警系统因干扰事件而发出的异常误报,又可以避免地震时的正常警报被错误... 详细信息

针对我国高速铁路地震预警系统因非地震事件干扰而产生的误报,基于地震波在2个台站之间的幅值衰减关系,提出1种高速铁路地震预警系统事件确认方法,既可以及时解除预警系统因干扰事件而发出的异常误报,又可以避免地震时的正常警报被错误解除。利用收集得到的各种干扰记录和世界各国强震动数据,对本文方法进行干扰事件测试和地震事件测试,考察其解除误报、避免漏报的能力。模拟测试结果表明:本文方法误报率为1.2%,误报解除延迟均值为12.5 s,漏报率为0%,满足《高速铁路地震预警监测系统技术条件》要求,兼顾了实时性和准确率;误报解除延迟与台站密度和地震波形相关,密度越高延迟越小、地震波幅值增长越快延迟越小;综合运用本文方法与我国高速铁路地震预警系统前端智能识别算法,可及时解除预警系统发出的所有误报。

关键词：高速铁路地震预警系统抗震防灾衰减关系误报解除