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Memristive switching in the surface of a charge-density-wave topological semimetal

Science Bulletin 2024年第13期69卷 2042-2049页

作者： Jianwen Ma xianghao meng Binhua Zhang Yuxiang Wang Yicheng Mou Wenting Lin Yannan Dai Luqiu Chen Haonan Wang Haoqi Wu Jiaming Gu Jiayu Wang Yuhan Du Chunsen Liu Wu Shi Zhenzhong Yang Bobo Tian Lin Miao Peng Zhou Chun-Gang Duan Changsong Xu Xiang Yuan Cheng Zhang State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing Fudan UniversityShanghai 200433China State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200241China Key Laboratory of Computational Physical Sciences(Ministry of Education) Institute of Computational Physical SciencesState Key Laboratory of Surface PhysicsDepartment of PhysicsFudan UniversityShanghai 200433China Shanghai Qi Zhi Institute Shanghai 200030China School of Physics Southeast UniversityNanjing 211189China Key Laboratory of Polar Materials and Devices(Ministry of Education) Department of ElectronicsEast China Normal UniversityShanghai 200241China Shanghai Center of Brain–inspired Intelligent Materials and Devices East China Normal UniversityShanghai 200241China State Key Laboratory of ASIC and System School of MicroelectronicsFudan UniversityShanghai 200433China Frontier Institute of Chip and System Fudan UniversityShanghai 200433China Zhangjiang Fudan International Innovation Center Fudan UniversityShanghai 201210China School of Physics and Electronic Science East China Normal UniversityShanghai 200241China

Owing to the outstanding properties provided by nontrivial band topology,topological phases of matter are considered as a promising platform towards low-dissipation electronics,efficient spin-charge conversion,and topological quantum *** ferroelectricity in topological materials enables the non-volatile control of the quantum states,which could greatly facilitate topological electronic ***,ferroelectricity is generally incompatible with systems featuring metallicity due to the screening effect of free *** this study,we report the observation of memristive switching based on the ferroelectric surface state of a topological semimetal(TaSe_(4))*** find that the surface state of(TaSe_(4))2I presents out-of-plane ferroelectric polarization due to surface *** the combination of ferroelectric surface and charge-density-wave-gapped bulk states,an electric-switchable barrier height can be achieved in(TaSe_(4))2I-metal *** employing a multi-terminal-grounding design,we manage to construct a prototype ferroelectric memristor based on(TaSe_(4))2I with on/off ratio up to 103,endurance over 103 cycles,and good retention *** origin of the ferroelectric surface state is further investigated by first-principles calculations,which reveal an interplay between ferroelectricity and band *** emergence of ferroelectricity in(TaSe_(4))2I not only demonstrates it as a rare but essential case of ferroelectric topological materials,but also opens new routes towards the implementation of topological materials in functional electronic devices.

关键词： Topological semimetal Schottky barrier Surface ferroelectricity Memristor

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致密储层压驱焖井阶段渗吸机理分子模拟研究

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力学学报 2024年第6期56卷 1624-1634页

作者：王凤娇孟详昊刘义坤徐贺胡超洋东北石油大学提高油气采收率教育部重点实验室黑龙江大庆163318 大庆石油管理局博士后工作站黑龙江大庆163453 东北石油大学三亚海洋油气研究院海南三亚572025

针对致密储层开发中存在的天然地层能量衰减快、驱替相有效波及体积不足等难题,考虑将压驱与焖井相结合的高效开发技术应用于致密储层.基于分子动力学方法从微观作用力角度分析致密储层压驱渗吸机理,进行致密储层压驱过程溶质动态迁移表... 详细信息

针对致密储层开发中存在的天然地层能量衰减快、驱替相有效波及体积不足等难题,考虑将压驱与焖井相结合的高效开发技术应用于致密储层.基于分子动力学方法从微观作用力角度分析致密储层压驱渗吸机理,进行致密储层压驱过程溶质动态迁移表征,并从分子尺度对渗吸阶段进行划分.采用分子模拟方法,构建致密储层壁面-油相-驱替相三相体系,分别从体系弛豫特征、浓度分布及扩散能力和介质间相互作用能等方面分析常规水力压裂后常压驱替条件和压驱高压条件渗吸过程特征性差异,从分子尺度阐释致密储层压驱渗吸机理.研究表明:相对于常规压裂后驱替而言,压驱条件下,驱替相分子扩散系数提高20.06%,与孔隙壁面的相互作用能提高2.3倍;驱替相分子吸附层数增加,油相解吸效果更为明显,渗吸换油效率提高38.73%.此外,渗吸效率随储层温度变化的过程存在峰值,具有先上升后降低的特征;且受到壁面润湿性的影响,壁面亲水性越强渗吸效率越高.从分子尺度将焖井渗吸过程划分为3个阶段:水分子优先靠近壁面;驱替相流体与油相分子竞争吸附,将吸附态油相剥离为游离态,使其远离壁面;压驱液溶质分子进入初始油相范围,进一步置换油相,提高渗吸效率.压驱技术高压注入压驱剂可快速补充地层能量,扩大驱替相流体波及体积并提高洗油效率,在二者的协同作用下可大幅度提高渗吸驱油效率.该项研究可为致密储层高效开发提供理论参考.

关键词：致密储层压驱技术焖井渗吸机理分子动力学

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多RIS辅助通信网络协同传输性能研究

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无线电通信技术 2024年第2期50卷 303-311页

作者：孟祥浩安康施育鑫林志南京信息工程大学电子与信息工程学院江苏南京210044 国防科技大学第六十三研究所江苏南京210007 国防科技大学电子对抗学院安徽合肥230037

研究了多智能超表面(Reconfigurable Intelligent Surface, RIS)辅助的无线系统的传输性能。在无线信道传播环境中部署多个相同几何尺寸的RIS,考虑不同RIS所关联的无线信道是独立非同分布且具有不同的分布和统计特性,基于上述系统模型... 详细信息

研究了多智能超表面(Reconfigurable Intelligent Surface, RIS)辅助的无线系统的传输性能。在无线信道传播环境中部署多个相同几何尺寸的RIS,考虑不同RIS所关联的无线信道是独立非同分布且具有不同的分布和统计特性,基于上述系统模型提出了两种目标导向的多RIS辅助方案,即穷举式(Exhaustive RIS-Aided, ERA)和机会式(Opportunistic RIS-Aided, ORA)方案。利用基于矩量法的端到端信道数学模型,可以将端到端信道系数近似为伽马分布,从中断概率(Outage Probability, OP)和各态历经容量(Ergodic Capacity, EC)两种性能指标分别对两种方案的性能进行评估。通过研究EC的上下界,提供了快速估算可达传输速率的方法。结果表明ORA方案可以优化能量效率,ERA方案在OP和EC方面优于ORA方案。

关键词：智能超表面性能分析伽马分布各态历经容量中断概率

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多运营商5G网络速率测评方法

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电信快报 2024年第8期 31-37页

作者：孟翔浩杨雪瑾祁超上海市无线电监测站上海市200031

公众对于5G移动通信网络的用户感知度反映了公众对于整个网络的网络质量的感受。文章通过仿真测试的方法,设计单运营商串行、并行,多运营商交替测试以及多运营商并行测试等方案,针对上下行速率等关键网络质量指标进行测试,分析各测试方... 详细信息

公众对于5G移动通信网络的用户感知度反映了公众对于整个网络的网络质量的感受。文章通过仿真测试的方法,设计单运营商串行、并行,多运营商交替测试以及多运营商并行测试等方案,针对上下行速率等关键网络质量指标进行测试,分析各测试方案的影响因素,并就各方案的结果进行评估,为今后5G移动通信网络质量用户感知度测试提供依据。

关键词：移动通信网络用户感知度测评上下行速率多运营商 5G网络速率测试

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基于时空图神经网络的异构交通参与者风险预测

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汽车工程 2024年第9期46卷 1537-1545页

作者：孟相浩牛凌席军强陈丹妮吕超北京理工大学机械与车辆学院北京100081 清华大学深圳国际研究生院深圳518055

有效预测驾驶员视野下的多交通参与者未来风险指标是为人类驾驶员提供风险预警,规避潜在碰撞风险的关键。大多数现有对风险的研究仅考虑场景中单一个体与本车之间的成对交互关系,并从评估而非预测的角度展开研究,而忽略异构交通参与者... 详细信息

有效预测驾驶员视野下的多交通参与者未来风险指标是为人类驾驶员提供风险预警,规避潜在碰撞风险的关键。大多数现有对风险的研究仅考虑场景中单一个体与本车之间的成对交互关系,并从评估而非预测的角度展开研究,而忽略异构交通参与者之间不同的交互关系及未来风险状态。本文提出了一种基于时空图卷积神经网络的异构多目标风险预测方法Risk-STGCN,通过图卷积及时间卷积分别对单帧场景图信息与时序信息进行学习,结合多层时序预测网络对多目标风险指标TTC进行预测。在开源BLVD与实车自采数据集上进行了训练验证,并与常用序列预测模型进行对比。实验结果表明,所提模型在不同数据集上的平均TTC误差均在0.95 s以下,多实验指标均优于文中所提到的其他模型,具有良好的鲁棒性,同时提升了复杂交通场景下风险预测的可解释性。

关键词：智能汽车多交通参与者交互表征风险预测时空图神经网络

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Transparent exopolymer particles(TEPs)-associated protobiofilm:A neglected contributor to biofouling during membrane filtration

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Frontiers of Environmental Science & Engineering 2021年第4期15卷 205-214页

作者： Shujuan meng Rui Wang Kaijing Zhang xianghao meng Wenchao Xue Hongju Liu Dawei Liang Qian Zhao Yu Liu School of Space and Environment Beihang UniversityBeijing100191China Department of Energy Environment and Climate ChangeSchool of EnvironmentResources and DevelopmentAsian Institute of TechnologyP.O.Box 4Klong LuangPathumthani12120Thailand School of Municipal and Environmental Engineering Shandong Jianzhu UniversityJinan250101China School of Civil and Environmental Engineering Nanyang Technological UniversitySingapore639798Singapore

Transparent exopolymer particles(TEPs)are a class of transparent gel-like polysaccharides,which have been widely detected in almost every kind of feed water to membrane systems,including freshwater,seawater and *** TEP have been thought to be related to the membrane fouling,little information is currently available for their influential mechanisms and the pertinence to biofouling *** present study,thus,aims to explore the impact of TEPs on biofouling development during *** samples were inoculated with bacteria for several hours before filtration and the formation of“protobiofilm”(pre-colonized TEP by bacteria)was examined and its influence on biofouling was *** was observed that the bacteria can easily and quickly attach onto TEPs and form *** experiments further revealed that TEP-protobiofilms served as carriers which facilitated and accelerated transport of bacteria to membrane surface,leading to rapid development of biofouling on the ultrafiltration membrane ***,compared to the feed water containing independent bacteria and TEPs,more flux decline was observed with ***,it appeared from this study that TEP-protobiofilms play a vital role in the development of membrane biofouling,but unfortunately,this phenomenon has been often overlooked in the ***,these findings in turn may also challenge the current understanding of organic fouling and biofouling as membrane fouling caused by TEP-protobiofilm is a combination of *** is expected that this study might promote further research in general membrane fouling mechanisms and the development of an effective mitigation strategy.

关键词： Transparent exopolymer particles(TEPs) TEP-protobiofilm Bacteria attachment Biofouling of membrane

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考虑结构非线性的轴系传动随机振动响应分析

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机械与电子 2024年第6期42卷 45-49页

作者：孟祥昊于坤鹏王志海中国电子科技集团公司第三十八研究所安徽合肥230088

为了研究转轴结构中零件配合状态、间隙等非线性因素对其随机振动响应的影响,基于显式动力学分析,在时域内对转轴结构的随机振动响应进行了仿真。结果表明处于紧密配合状态的零件间振动传递更加平顺,响应幅值小于临界状态。当结构存在... 详细信息

为了研究转轴结构中零件配合状态、间隙等非线性因素对其随机振动响应的影响,基于显式动力学分析,在时域内对转轴结构的随机振动响应进行了仿真。结果表明处于紧密配合状态的零件间振动传递更加平顺,响应幅值小于临界状态。当结构存在间隙时,其响应幅值随着间隙的增大而显著下降,但零件间的碰撞会导致结构高频段的响应增加,同时也会加剧零件的磨损。研究结论可以为结构的设计理念和选型方法提供参考。

关键词：随机振动非线性时域仿真

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The effect of thermal fluid derived from mud diapir on sandstone reservoirs in the Yinggehai Basin, South China Sea

Energy Geoscience

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Energy Geoscience 2022年第4期3卷 473-484页

作者： Xiaowei Lv Meiyan Fu Shaonan Zhang Yi Liu Xiaoqi Ding xianghao meng Shuai Yin Tengjiao Sun State Key Laboratory of Oil and Gas Geology and Exploitation Chengdu610059China College of Energy Resource Chengdu University of TechnologyChengdu610059China Research Institute of SINOPEC Henan Oilfield Company Zhengzhou450018China College of Geosciences and Technology Southwest Petroleum UniversityChengdu610500China Research Institute of CNOOC Zhanjiang Branch Company Zhanjiang524059China School of Earth Sciences and Engineering of Xian Shiyou University Xian710065China

The underground thermal fluid is one of the significant factors controlling the formation and quality of *** Huangliu Formation(N_(1)h)in YF1 area of the central depression belt in the Yinggehai Basin,South China Sea,is characterized by intense thermal fluid activities related to mud diapir and large-scale shallow-water gravity flow *** multi-episodic invasion of high-temperature and CO_(2)-rich thermal fluid into the formation induces complex water-rock reaction during diagenetic pro-cess,providing a preferable investigation opportunity for revealing how thermal fluid affects reservoir *** study characterizes the reservoirs in the formation through core and thin section analyses as well as physical property *** reservoirs are dominated by fine-grained sandstone characterized by medium porosity(15.2-21.3%)and lower permeability(0.56-15.75mD).Based on an analysis of casting thin section,cathode luminescence(CL),scanning electron microscope(SEM),carbon and oxygen isotope,inclusion test,and electron-probe microanalysis(EPMA),we systematically investigate the diagenetic patterns and pore evolution process for the reservoirs in the *** episodic invasion of thermal fluid occurred approximately 0.4 Ma ago plays an important role in controlling reservoir development:The CO_(2)-rich formation water induces massive late-stage dissolution,resulting in a higher proportion of dissolved pores(38.7-46.4%),which improves the porosity of reservoirs at a depth of 2600-3100 ***,the late dissolution together with carbonate cementation occurred in closed diagenetic system blocks most seepage ***,the relatively high level clay mineral transformation in the YF1 area leads to a higher content of authigenic illite(44-62%)in the *** authigenic illite severely blocks the pore throats in fine sandstone,reducing *** study offers an insight to the understanding of mud diapir-derived thermal fluid

关键词： Thermal fluid Sandstone diagenesis CO_(2)dissolution Low permeability Huangliu Formation

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Harmonically pump a femtosecond optical parametric oscillator to 1.13 GHz by a femtosecond 515 nm laser

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Chinese Optics Letters 2020年第3期18卷 57-61页

作者： Jiajun Song xianghao meng Zhaohua Wang Xianzhi Wang Wenlong Tian Jiangfeng Zhu Shaobo Fang Hao Teng Zhiyi Wei Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China School of Physics and Optoelectronic Engineering Xidian UniversityXi’an 710071China

We demonstrate a harmonically pumped femtosecond optical parametric oscillator(OPO)laser using a frequency-doubled mode-locked Yb:KGW laser at a repetition rate of 75.5 MHz as the pump *** on a bismuth borate nonlinear crystal,repetition rates up to 1.13 GHz are realized,which is 15 times that of the pump *** signal wavelength is tunable from 700 nm to 887 *** maximum power of the signal is 207 m W at the central wavelength of 750 nm and the shortest pulse duration is 117 fs at 780 *** beam quality(M^2 factor)in the horizontal and vertical directions of the output beam are 1.077 and 1.141,respectively.

关键词： GHz femtosecond laser optical parametric oscillator tunable wavelength

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A disk I/O optimized system for concurrent graph processing jobs

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Frontiers of Computer Science 2024年第3期18卷 13-29页

作者： xianghao XU Fang WANG Hong JIANG Yongli CHENG Dan FENG Peng FANG School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Department of Computer Science&Engineering University of Texas at ArlingtonArlingtonTX 76019USA College of Computer and Data Science Fuzhou UniversityFuzhou 350108China Zhejiang Lab Hangzhou 311121China

In order to analyze and process the large graphs with high cost efficiency,researchers have developed a number of out-of-core graph processing systems in recent years based on just one commodity *** the other hand,with the rapidly growing need of analyzing graphs in the real-world,graph processing systems have to efficiently handle massive concurrent graph processing(CGP)***,due to the inherent design for single graph processing job,existing out-of-core graph processing systems usually incur unnecessary data accesses and severe competition of I/O bandwidth when handling the CGP *** this paper,we propose GraphCP,a disk I/O optimized out-of-core graph processing system that efficiently supports the processing of CGP *** proposes a benefit-aware sharing execution model to share the I/O access and processing of graph data among the CGP jobs and adaptively schedule the graph data loading based on the states of vertices,which efficiently overcomes above challenges faced by existing out-of-core graph processing ***,GraphCP adopts a dependency-based future-vertex updating model so as to reduce disk I/Os in the future *** addition,GraphCP organizes the graph data with a Source-Sorted Sub-Block graph representation for better processing capacity and I/O access *** evaluation results show that GraphCP is 20.5×and 8.9×faster than two out-of-core graph processing systems GridGraph and GraphZ,and 3.5×and 1.7×faster than two state-of-art concurrent graph processing systems Seraph and GraphSO.

关键词： graph processing disk I/O concurrent jobs

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