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Interhemispheric Comparison of Dipole Tilt Angle Effects on Latitude of Mid-Altitude Cusp

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Chinese Physics Letters 2008年第5期25卷 1916-1918页

作者：郭建广史建魁 zhang tie-long 刘振兴 State Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 Graduate University of Chinese Academy of Sciences Beijing 100049 Spaze Research Institute Austrian Academy of Sciences Graz Austria

A statistical study of interhemispheric comparison of dipole tilt angle effect on the latitude of the mid-altitude cusp is preformed by a data set of the Cluster cusp crossings over a 5-year period. The result shows that the dipole tilt angle has a clear control of the cusp latitudinal location. When the dipole tilts sunwards, the cusp is shifted poleward. The northern cusp moves 1° ILAT for every 15.4° increase in the dipole tilt angle, while the southern cusp moves 1° ILAT for every 20.8° increase in the dipole tilt angle. This suggests that an interhemispheric difference appears in the dependence of cusp latitudinal location on the dipole tilt angle.

关键词： MAGNETOSPHERIC CUSPS MAGNETIC-FIELD LOCATION DEPENDENCE CURRENTS PLASMA

Probability of Field-Aligned Currents Observed by the Satellite Cluster in the Magnetotail

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Chinese Physics Letters 2007年第4期24卷 1125-1127页

作者：程征伟史建魁 zhang tie-long 刘振兴 State Key Laboratory for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 Space Research Institute Austrian Academy of Sciences Graz Austria Graduate University of Chinese Academy of Sciences Beijing 100049

Field-aligned current （FAC） density distribution at the plasma sheet boundary layers is statistically studied. The FAC is calculated by the so-called curlometer technique with the data from FGM onboard the four Cluster spacecraft in 2001. By calculation we obtain a large number of FAC samples. In the samples, most of calculated FAC densities were very small and around zero caused by some errors or noise. In order to get the real FAC density distribution in the magnetotail, we use a three-Gaussian distribution to fit the errors, then subtract the estimated error contribution from the full distribution and obtain the FAC density distribution. The result shows that the FAC occurrence versus its density has a distribution consisting of a Gauss/an distribution with an additional decreasing exponential distribution. The most probable value of the FAC density is 3.45 pT/km.

关键词： PLASMA SHEET BOUNDARY SUBSTORMS LAYER

Field-Aligned Currents at the PSBL on 17 August 2001 Storm: Relationships with solar Wind Conditions

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Chinese Physics Letters 2011年第9期28卷 267-270页

作者： CHENG Zheng-Wei SHI Jian-Kui zhang tie-long WANG Sheng-Guo LIU Zhen-Xing State Key Laboratory of Space Weather CSSAR/CASBeijing 100190 Space Research Institute Austrian Academy of SciencesGrazAustria Beijing Institute of Applied Meteorology Beijing 100083

Using magnetic field and plasma data acquired with Cluster spacecrafts,we investigate the relationship between the field-aligned currents(FACs)at the plasma sheet boundary layer(PSBL)and solar wind dynamic pressure,as well as the interplanetary magnetic field(IMF)By on 17 August 2001 *** studies reveal that FAC density at the PSBL in the magnetotail in the storm time is controlled mainly by the solar wind dynamic pressure rather than IMF *** FACs at the PSBL are associated with the low−altitude region-1 current and have the same polarity as region-1 current in the dawn *** the polar region,the footprints of the FACs at the PSBL expand *** data analysis also shows that a very strong FAC with a density over 40 nA·m^(−2) appeared in this storm time when a substorm just occurred.

关键词： storm altitude Wind

磁尾的等离子体片边界层场向电流密度与地磁活动指数Kp的关系分析

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中国科学：技术科学 2011年第11期41卷 1499-1504页

作者：程征伟史建魁 zhang tie long DUNLOP Malcolm 刘振兴中国科学院空间科学与应用研究中心空间天气学国家重点实验室北京100190 Space Research Institute Austrian Academy of Sciences Graz A-8010 Austria SSTD Rutherford Appleton Laboratory SW7 2AZ UK

对2001年7月～10月Cluster穿越磁尾等离子体片边界层期间观测到的172个场向电流事件进行了研究,主要分析了等离子体片边界层场向电流特性与地磁活动指数之间的关系.研究结果表明:1)等离子体片边界层场向电流的相对发生率随地磁活动的增... 详细信息

对2001年7月～10月Cluster穿越磁尾等离子体片边界层期间观测到的172个场向电流事件进行了研究,主要分析了等离子体片边界层场向电流特性与地磁活动指数之间的关系.研究结果表明:1)等离子体片边界层场向电流的相对发生率随地磁活动的增强而增加;2)等离子体片边界层场向电流密度随Kp指数的增大而增大;在磁暴的主相阶段,场向电流迅速增大,电流密度最大达到19.05nA/m2,同时Kp增大至5;3)地磁活动指数Kp与等离子体片边界层区场向电流密度有着一致的变化关系.然而,当AE800nT时,场向电流密度随着AE的增加而减小.从而说明,等离子体片边界层场向电流密度与Kp指数的变化关系更为密切.

关键词：场向电流等离子体片边界层 Kp指数 AE指数

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Frequency Domain Fatigue Evaluation on SCR Girth-Weld Based on Structural Stress

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China Ocean Engineering 2024年第2期38卷 255-270页

作者： zhang long ZHAO Tian-feng College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

The Steel Catenary Riser(SCR)is a vital component for transporting oil and gas from the seabed to the floating *** harsh environmental conditions and complex platform motion make the SCR’s girth-weld prone to fatigue *** structural stress fatigue theory and Master S-N curve method provide accurate predictions for the fatigue damage on the welded joints,which demonstrate significant potential and compatibility in multi-axial and random fatigue ***,we propose a new frequency fatigue model subjected to welded joints of SCR under multiaxial stress,which fully integrates the mesh-insensitive structural stress and frequency domain random process and transforms the conventional welding fatigue technique of SCR into a spectrum analysis technique utilizing structural ***,a full-scale FE model of SCR with welds is established to obtain the modal structural stress of the girth weld and the frequency response function(FRF)of modal coordinate,and a biaxial fatigue evaluation about the girth weld of the SCR can be achieved by taking the effects of multi-load correlation and pipe-soil interaction into *** research results indicate that the frequency-domain fatigue results are aligned with the time-domain results,meeting the fatigue evaluation requirements of the SCR.

关键词： SCR girth weld random vibration self(cross)power spectrum structural stress method biaxial fatigue damage

Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 184-194页

作者： Ruiying zhang Fan Jiang long Xue School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Beijing Academy of Safety Engineering and Technology Beijing 102617China College of Mechanical and Energy Engineering Beijing University of TechnologyBeijing 100124China

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive *** this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial *** results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was *** the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting *** average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc *** minimum melting amount was not affected by the wire-torch distance under any current separation ratio *** the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch *** the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch *** effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation *** this study,the decoupling mechanism and ability of this innovative

关键词： Twin-body plasma arc Melting control ability Melting amount Current separation ratio

Chien-physics-informed neural networks for solving singularly perturbed boundary-layer problems

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1467-1480页

作者： long WANG Lei zhang Guowei HE The State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

A physics-informed neural network(PINN)is a powerful tool for solving differential equations in solid and fluid ***,it suffers from singularly perturbed boundary-layer problems in which there exist sharp changes caused by a small perturbation parameter multiplying the highest-order *** this paper,we introduce Chien's composite expansion method into PINNs,and propose a novel architecture for the PINNs,namely,the Chien-PINN(C-PINN)*** novel PINN method is validated by singularly perturbed differential equations,and successfully solves the wellknown thin plate bending *** particular,no cumbersome matching conditions are needed for the C-PINN method,compared with the previous studies based on matched asymptotic expansions.

关键词： physics-informed neural network(PINN) singular perturbation boundarylayer problem composite asymptotic expansion

Design Strategies for Aqueous Zinc Metal Batteries with High Zinc Utilization: From Metal Anodes to Anode-Free Structures

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Nano-Micro Letters 2024年第4期16卷 305-349页

作者： Xianfu zhang long zhang Xinyuan Jia Wen Song Yongchang Liu School of Materials Science and Engineering University of Science and Technology Beijing30 College RoadBeijing 100083People’s Republic of China Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyState Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing 100083People’s Republic of China

Aqueous zinc metal batteries(AZMBs)are promising candidates for next-generation energy storage due to the excellent safety, environmental friendliness, natural abundance, high theoretical specific capacity, and low redox potential of zinc(Zn) metal. However,several issues such as dendrite formation, hydrogen evolution, corrosion, and passivation of Zn metal anodes cause irreversible loss of the active materials. To solve these issues, researchers often use large amounts of excess Zn to ensure a continuous supply of active materials for Zn anodes. This leads to the ultralow utilization of Zn anodes and squanders the high energy density of AZMBs. Herein, the design strategies for AZMBs with high Zn utilization are discussed in depth, from utilizing thinner Zn foils to constructing anode-free structures with theoretical Zn utilization of 100%, which provides comprehensive guidelines for further research. Representative methods for calculating the depth of discharge of Zn anodes with different structures are first summarized. The reasonable modification strategies of Zn foil anodes, current collectors with pre-deposited Zn, and anode-free aqueous Zn metal batteries(AF-AZMBs) to improve Zn utilization are then detailed. In particular, the working mechanism of AF-AZMBs is systematically introduced. Finally, the challenges and perspectives for constructing high-utilization Zn anodes are presented.

关键词： Aqueous zinc metal batteries Zinc anodes High zinc utilization Depth of discharge Anode-free structures

Accumulated-state-error-based event-triggered sampling scheme and its application to H∞ control of sampled-data systems

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Science China(Information Sciences) 2024年第6期67卷 328-341页

作者： Xian-Ming zhang Qing-long HAN Bao-Lin zhang Xiaohua GE Dawei zhang School of Science Computingand Engineering TechnologiesSwinburne University of Technology College of Automation and Electronic Engineering Qingdao University of Science & Technology School of Mathematics Shandong University

This paper is concerned with event-triggered H∞control of sampled-data systems. Its novelties lie in three aspects:（i） A novel accumulated-state-error-based event-triggered scheme is introduced by comparing the integral of the state error from tk to t with the system state sampled at tk. This condition works well due to the fact that the so-called Zeno behaviour does not occur.（ii） A novel Lyapunov functional is constructed to establish a criterion to ensure some certain H∞performance of the closed-loop system. This Lyapunov functional is dependent on the integral of the state error involved in the event-triggered scheme.（iii） Under the event-triggered sampling scheme, suitable state-feedback controllers can be designed rather than be given a priori. Moreover, a self-triggered implementation of the proposed event-triggered sampling scheme is presented as well. Finally, a batch reactor model and an inverted pendulum system are given to demonstrate the effectiveness of the proposed method.

关键词： event-triggered sampling self-triggered implementation $H_\infty$ control looped-functional