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Qualitative Analyses of Correlations between Strong Ground Motions of the Three Large Earthquakes and Landslide Distributions

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Journal of Earth Science 2023年第2期34卷 369-380页

作者： yuzhu bai Chong Xu Institute of Geology China Earthquake AdministrationBeijing 100029China National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing 100085China Key Laboratory of Compound and Chained Natural Hazards Dynamics Ministry of Emergency Management of ChinaBeijing 100085China

In this work,the correlations between spatial distributions of landslide point density(LPD)and strong ground motions of the three strong earthquakes are qualitatively investigated.Meanwhile the qualitative relationship between the distribution of LPD and the fault rupture process is also characterized.Three strong events are the Lushan,Wenchuan,and Jiuzhaigou earthquakes.In order to reconstruct the near filed strong ground motions and the fault processes of these earthquakes,the broadband ground simulation method of University of California Santa Barbara(UCSB)and the simplified crustal layer structures are applied.To show the rationality of the UCSB method,the fault slip distributions of the three earthquakes reconstructed by the kinematic rupture generator model in the UCSB method are compared with those by inversed.Furthermore,the validation of the UCSB method for the three earthquakes is also carried according to the validation exercise of the Southern California Earthquake Center(SCEC)Broadband Platform(BBP).Lastly,the fields of peak ground acceleration(PGA)and peak ground velocity(PGV)in three mutually perpendicular directions of the three earthquakes are achieved.Generally,the landslide distribution length of large LPD values along the fault strike is less than the fault strike length.Therefore,the slip modes of earthquake faults affect the distributions of landslides.For the strike slip earthquakes,the distributions of large LPD values relate well to PGA and PGV components of the parallel and normal to the fault strike.For the reverse slip earthquakes,distributions of LPD relate to ground motion components in all directions.Moreover,distributions of landslides in near fields of earthquakes are significantly affected by the focus parameters and fault scales.

关键词： Lushan earthquake Wenchuan earthquake Jiuzhaigou earthquake landslide ground motions engineering geology

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Gaussian mixture model based adaptive control for uncertain nonlinear systems with complex state constraints

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Chinese Journal of Aeronautics 2022年第5期35卷 361-373页

作者： yuzhu bai Rong CHEN Yong ZHAO Yi WANG College of Aerospace and Engineering National University of Defense TechnologyChangsha 410073China Nanjing Research Institute of Electronics Technology Nanjing 210000China

This paper addresses an uncertain nonlinear control system problem with complex state constraints and mismatched uncertainties.A novel Gaussian Mixture Model(GMM)based adaptive PID-Nonsingular Terminal Sliding Mode Control(NTSMC)(GMM-adaptive-PID-NTSMC)method is proposed.It is achieved by combining a GMM based adaptive potential function with a novel switching surface of PID-NTSMC.Next,the stability of the closed-loop system is proved.The main contribution of this paper is that the GMM method is applied to obtain the analytic description of the complex bounded state constraints,ensuring that the states'constraints are not violated with GMM-based adaptive potential function.The developed potential function can consider the influence of uncertainties.More importantly,the GMM-adaptive-PID-NTSMC can be generalized to control a more representative class of uncertain nonlinear systems with constrained states and mismatched uncertainties.In addition,the proposed controller enhances the robustness,and requires less control cost and reduces the steady state error with respect to the Artificial Potential Function based Nonsingular Terminal Sliding Mode Control(APF-NTSMC),GMM-NTSMC and GMM-adaptive-NTSMC.At last,numerical simulation is performed to validate the superior performance of the proposed controller.

关键词： Gaussian mixture model Nonlinear systems State constrained Terminal sliding mode control Uncertain

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Extrusion deformation process of ground surface during the Lushan earthquake in China

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Geodesy and Geodynamics 2017年第2期8卷 84-89页

作者： yuzhu bai Key Laboratory of Active Tectonics and Volcano Institute of GeologyChina Earthquake Administration

Based on finite element method, the extrusion deformation process of ground surface during the Lushan earthquake （April 20, 2013） is investigated in this work. In order to construct the finite element model of Lushan earthquake structure, the geophysical layer model of Lushan area, the frictional characteristic of slip-weaken along the fault surface, and the Coulomb failure criterion are considered. Through the computation and the comparison with achievement on the Lushan focal dynamics, our researches indicate that：（1） The most extrusion deformation of ground surface occurred in the initial phase of earthquake procession, i.e., between the fourth and sixth seconds after the earthquake occurred. （2） Between the first and sixth seconds after the earthquake, the extrusion deformation concentrates on the surface projection of earthquake fault. （3） Between the first and third seconds after the earthquake, the extrusion deformation of ground surface is very tiny. Meanwhile, the extrusion deformation reaches maximum at the sixth second after earthquake. （4） After 6 s of Lushan earthquake, the extrusion deformation spread out of earthquake structure projection. （5） During the earthquake, the maximum of extrusion deformation on ground surface is larger than the final deformation of the post-earthquake, in other words, the ground extrusion deformation will lastly reach a relatively small value after the Lushan earthquake occurred.

关键词： Lushan earthquake Extrusion deformation Finite element method

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The qualitative analyses of correlations between strong ground motions of the three large earthquakes and landslide distributions

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Journal of Earth Science 2021年

作者： yuzhu bai Chong Xu Institute of Geology China Earthquake Administration

In this work， the correlations between spatial distributions of landslide point density (LPD) and strong ground motions of the three strong earthquakes are qualitatively investigated. Meanwhile the qualitative relationship between the distribution of LPD and the fault rupture process is also characterized. Three strong events are the Lushan， Wenchuan， and Jiuzhaigou earthquakes. In order to reconstruct the near filed strong ground motions and the fault processes of these earthquakes， the broadband ground simulation method of University of California Santa Barbara (UCSB) and the simplified crustal layer structures are applied. To show the rationality of the UCSB method， the fault slip distributions of the three earthquakes reconstructed by the kinematic rupture generator model in the UCSB method are compared with those by inversed. Furthermore， the validation of the UCSB method for the three earthquakes is also carried according to the validation exercise of the Southern California Earthquake Center (SCEC) Broadband Platform (BBP). Lastly， the fields of peak ground acceleration (PGA) and peak ground velocity (PGV) in three mutually perpendicular directions of the three earthquakes are achieved. Generally， the landslide distribution length of large LPD values along the fault strike is less than the fault strike length. Therefore， the slip modes of earthquake faults affect the distributions of landslides. For the strike slip earthquakes， the distributions of large LPD values relate well to PGA and PGV components of the parallel and normal to the fault strike. For the reverse slip earthquakes， distributions of LPD relate to ground motion components in all directions. Moreover， distributions of landslides in near fields of earthquakes are significantly affected by the focus parameters and fault scales.

关键词： Lushan earthquake Wenchuan earthquake Jiuzhaigou earthquake Landslide Ground motions

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基于测地线的航天器集群隐蔽机动轨迹规划

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宇航学报 2024年第4期45卷 513-522页

作者：王璟贤白玉铸陈致钧郑中旭赵勇陈小前国防科技大学空天科学学院长沙410073 军事科学院北京100091

针对航天器集群隐蔽机动问题,提出一种基于测地线的航天器集群轨迹规划方法。该方法将轨迹规划问题抽象到微分流形拓扑空间中,通过数学定义赋予空间结构度量。首先将集群的运动约束、避撞约束以及隐蔽构型约束等非凸约束集成到度量中,... 详细信息

针对航天器集群隐蔽机动问题,提出一种基于测地线的航天器集群轨迹规划方法。该方法将轨迹规划问题抽象到微分流形拓扑空间中,通过数学定义赋予空间结构度量。首先将集群的运动约束、避撞约束以及隐蔽构型约束等非凸约束集成到度量中,避免增加系统维度的同时无需进行约束凸化处理。进一步定义了一个依赖于流形度量的目标泛函,利用同伦变换将泛函局部极值问题转为偏微分方程求解问题。数值仿真结果表明,相比于模型预测-序列凸规划算法,该方法在解决了隐蔽机动非凸多约束问题的同时,具有不依赖于初始猜想、集群内部隐蔽覆盖性高和系统控制输入小的特点,能够为航天器集群提供有效的隐蔽机动轨迹。

关键词：航天器集群测地线隐蔽机动轨迹规划黎曼度量

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Spacecraft formation reconfiguration with multi-obstacle avoidance under navigation and control uncertainties using adaptive artificial potential function method

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Astrodynamics 2020年第1期4卷 41-56页

作者： Yi Wang Xiaoqian Chen Dechao Ran Yong Zhao Yang Chen yuzhu bai College of Aerospace Science and Engineering National University of Defense TechnologyChangsha410073China National Innovation Institute of Defense Technology Chinese Academy of Military SciencesBeijing10071China

In this paper,an adaptive artificial potential function(AAPF)method is developed for spacecraft formation reconfiguration with multi-obstacle avoidance under navigation and control uncertainties.Furthermore,an improved Linear Quadratic Regular(ILQR)is proposed to track the reference trajectory and a Lyapunov-based method is employed to demonstrate the stability of the overall closed-loop system.Compared with the traditional APF method and the equal-collision-probability surface(ECPS)method,the AAPF method not only retains the advantages of APF method and ECPS method,such as low computational complexity,simple analytical control law and easy analytical validation progress,but also proposes a new APF to solve multi-obstacle avoidance problem considering the influence of the uncertainties.Moreover,the ILQR controller obtains high control accuracy to enhance the safe performance of the spacecraft formation reconfiguration.Finally,the effectiveness of the proposed AAPF method and the ILQR controller are verified by numerical simulations.

关键词： spacecraft formation flying spacecraft formation reconfiguration collision avoidance artificial potential function uncertainties

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Apply of Explicit Finite Element in Seismic Ground Motion Computation

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Journal of Applied Mathematics and Physics 2013年第6期1卷 11-14页

作者： yuzhu bai Xiwei Xu Active Tectonics and Volcano Lab Key Lab of China Earthquake Administration Beijing China

In this paper, we will use the explicit finite element to compute ground motion due to Tangshan earthquake. The explicit finite-element method uses one integration point and an hourglass control scheme. We implement the coarse-grain method in a structured finite-element mesh straightforwardly. At the same time, we also apply the coarse-grain method to a widely used, slightly unstructured finite-element mesh, where unstructured finite elements are only used in the vertical velocity transition zones. By the finite-element methods, we can compute the ground velocity with some distance to the seismogenic fault in Tangshan earthquake. Through the computation, we can find the main character of ground motion for the strike slip earthquake events and the high frequency vibration motion of ground motion.

关键词： Finite-Element Method Fault Ground Motion Tangshan Earthquake

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Study on asymmetric interior corner flow in microgravity condition

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Science China(Technological Sciences) 2012年第8期55卷 2332-2337页

作者： LI JingHao CHEN XiaoQian HUANG YiYong bai yuzhu College of Aerospace and Materials Engineering National University of Defense TechnologyChangsha 410073China Subunit 91 Unit 91550 of People's Liberation ArmyDalian 116000China

The capillary flow in asymmetric interior corner consisting of straight vane and curved wall is studied with analytical solution.The concept of equivalent interior corner angle is proposed to convert the asymmetric interior corner model into symmetric interior corner model.Then the governing equations of interior corner flow are established,and based on which the interior corner flow is calculated.This method is used to analyze the capillary flow in cylindrical vane-type surface tension tank with outer vanes.The research can provide beneficial reference to the design of vane-type surface tension tank.

关键词：非对称微重力条件内角表面张力贮箱毛细管流动模型转换控制方程直叶片

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Reduced-Order Fixed-Time Control for Under-actuated Spacecraft Hovering

Reduced-Order Fixed-Time Control for Under-actuated Spacecra...

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第40届中国控制会议

作者： Yi Cao Zhijun Chen yuzhu bai Yong Zhao College of Aerospace Science and Engineering National University of Defense Technology

This paper proposes a Reduced-Order Fixed-Time Control（ROFTC） method for the hovering problem of the under-actuated spacecraft. Firstly, the dynamic equation of the under-actuated relative motion is established for the hovering mission of the under-actuated spacecraft, and the controllability of the system and the feasible set of hovering are analyzed. Then,under-actuated relative motion model is deduced by dimensionality reduction. Based on the reduced-order dynamics model, a fixed-time controller is proposed. The simulation results show that the under-actuated spacecraft can achieve hovering motion to the given position under the reduced-order fixed-time controller, and the system state can converge in a fixed time with high accuracy.

关键词： Under-actuated Spacecraft Hovering Fixed-Time Control Reduced-Order Control

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Highly Efficient Aligned Ion‑Conducting Network and Interface Chemistries for Depolarized All‑Solid‑State Lithium Metal Batteries

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Nano-Micro Letters 2024年第5期16卷 102-119页

作者： Yongbiao Mu Shixiang Yu yuzhu Chen Youqi Chu Buke Wu Qing Zhang Binbin Guo Lingfeng Zou Ruijie Zhang Fenghua Yu Meisheng Han Meng Lin Jinglei Yang Jiaming bai Lin Zeng Shenzhen Key Laboratory of Advanced Energy Storage Southern University of Science and TechnologyShenzhen 518055People’s Republic of China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055People’s Republic of China SUSTech Energy Institute for Carbon Neutrality Southern University of Science and TechnologyShenzhen 518055People’s Republic of China Department of Mechanical and Aerospace Engineering Hong Kong University of Science and TechnologyKowloon 997077Hong Kong Special Administrative Region of ChinaPeople’s Republic of China HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute FutianShenzhenPeople’s Republic of China

Improving the long-term cycling stability and energy density of all-solid-state lithium(Li)-metal batteries(ASSLMBs)at room temperature is a severe challenge because of the notorious solid–solid interfacial contact loss and sluggish ion transport.Solid electrolytes are generally studied as two-dimensional(2D)structures with planar interfaces,showing limited interfacial contact and further resulting in unstable Li/electrolyte and cathode/electrolyte interfaces.Herein,three-dimensional(3D)architecturally designed composite solid electrolytes are developed with independently controlled structural factors using 3D printing processing and post-curing treatment.Multiple-type electrolyte films with vertical-aligned micro-pillar(p-3DSE)and spiral(s-3DSE)structures are rationally designed and developed,which can be employed for both Li metal anode and cathode in terms of accelerating the Li+transport within electrodes and reinforcing the interfacial adhesion.The printed p-3DSE delivers robust long-term cycle life of up to 2600 cycles and a high critical current density of 1.92 mA cm^(−2).The optimized electrolyte structure could lead to ASSLMBs with a superior full-cell areal capacity of 2.75 mAh cm^(−2)(LFP)and 3.92 mAh cm^(−2)(NCM811).This unique design provides enhancements for both anode and cathode electrodes,thereby alleviating interfacial degradation induced by dendrite growth and contact loss.The approach in this study opens a new design strategy for advanced composite solid polymer electrolytes in ASSLMBs operating under high rates/capacities and room temperature.

关键词： All-solid-state lithium metal batteries Composite solid electrolyte 3D printing Areal capacity Interfacial degradation

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