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Non-uniform Berry-Esseen bound by unbounded exchangeable pairs approach

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Applied Mathematics(A Journal of Chinese Universities) 2021年第2期36卷 256-268页

作者： LIU Da-li LI Zheng WANG Han-chao CHEN zeng-jing Institute for Financial Studies Shandong UniversityJinan 250100China School of Mathematics Shandong UniversityJinan 250100China

In this paper,a new technique is introduced to obtain non-uniform Berry-Esseen bounds for normal and nonnormal approximations by unbounded exchangeable *** technique does not rely on the concentration inequalities dev... 详细信息

关键词： non-uniform Berry-Esseen bounds Stein's method exchangeable pairs

In-situ construction of a thermodynamically stabilized interface on the surface of single crystalline Ni-rich cathode materials via a onestep molten-salt route

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Nano Research 2023年第5期16卷 6771-6779页

作者： Huiya Yang Xiangbang Kong Jiyang Li Pengpeng Dai jing zeng Yang Yang Jinbao Zhao State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Centre of Chemistry for Energy MaterialsState-Province Joint Engineering Laboratory of Power Source Technology for New Energy VehicleEngineering Research Center of Electrochemical TechnologyMinistry of EducationCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China

Nickel rich LiNi_(x)Co_(y)Mn_(1−x−y)O_(2)cathode materials have been studied extensively to increase the energy density of lithium-ion batteries(LIBs)due to their advantages of high capacity and low ***,the anisotropic crystal expansion and contraction inside the secondary particles would cause detrimental micro-cracks and severe parasitic reactions at the electrode/electrolyte interface during cycling,which severely decreases the stability of crystalline structure and cathodeelectrolyte interphase and ultimately affects the calendar life of ***,a thermodynamically stabilized interface is constructed on the surface of single-crystalline Ni-rich cathode materials(SC811@RS)via a facile molten-salt route to suppress the generation of microcracks and interfacial parasitic side reactions *** functional theory calculations show that the formation energy of interface layer(−1.958 eV)is more negative than that of bulk layered structure(−1.421 eV).Such a thermodynamically stable protective layer can not only prevent the direct contact between highly reactive LiNi_(x)Co_(y)Mn_(1−x−y)O_(2)and electrolyte,but also mitigate deformation of structure caused by stress thus strengthening the mechanical *** spectra further confirm the excellent structural reversibility and reaction homogeneity of SC811@RS at particle,electrode,time ***,SC811@RS cathode material delivers significantly improved cycling stability(high capacity retention of 92%after 200 cycles at 0.5 C)compared with polycrystalline LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(82%).

关键词： LiNi_(x)Co_(y)Mn_(1−x−y)O_(2) single crystalline polycrystalline cathode lithium-ion battery

Suppressing the dissolution of vanadium by organic-inorganic hybrid for aqueous zinc-ion batteries

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Journal of Materials Science & Technology 2023年第14期145卷 93-100页

作者： Zexiang Luo Zhen Liu Hanbing He Zhihao Zhang Yong Chen Chaoqun Peng jing zeng School of Metallurgy and Environment Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China

Vanadium-based materials have been considered as the high promising cathodes for aqueous zinc ion batteries(ZIBs).Nevertheless,the dissolution of vanadium,the structural instability and the poor cy-cling stability largely hindered their *** organic frameworks(MOFs)and their deriva-tives attracted wide attention for their large specific surface area and structural ***,MOFs derived·VO_(2)·Zn_(2)V_(2)O_(7)(MVHA)as organic-inorganic hybrids were constructed by the in-situ substitution *** mixed valences of V 4+and V 5+between VO_(2)(B)and Zn_(2)V_(2)O_(7)were helpful to improve the electronic conductivity of MVHA cathode,and MOF-5-V acted as a physical barrier to inhibit the ca-thodic dissolution attributing to the particular organic frame *** obtained hybrid electrodes could deliver a high specific capacity(312.7 mA h g^(−1)at 1 A g^(−1)),and excellent long-term cycle stability(141.2 mA h g^(−1)after 1000 cycles at 10 A g^(−1)).Assistant density functional theory(DFT)calculations in-dicated that it has an ultra-low diffusion barrier of 0.32 eV for optimal Zn 2+diffusion path in *** intriguing idea of in-situ compositing vanadium oxide and MOFs derived material opens up a new research direction for high-energy secondary batteries.

关键词： Vanadium dioxide MOF-5 Aqueous zinc ion batteries Hybrid materials Dissolution

Safety evaluation for railway vehicles using an improved indirect measurement method of wheel–rail forces

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Journal of Modern Transportation 2016年第2期24卷 114-123页

作者： jing zeng Lai Wei Pingbo Wu State Key Laboratory of Traction Power Southwest Jiaotong University

The wheel-rail force measurement is of great importance to the condition monitoring and safety evaluation of railway vehicles. In this paper, an improved indirect method for wheel-rail force measurement is proposed to evaluate the running safety of railway vehicles. In this method, the equilibrium equations of a suspended wheelset are derived and the wheel-rail forces are then be obtained from measured suspension and inertia forces. This indirect method avoids structural modifications to the wheelset and is applicable to the long-term operation of railway vehicles. As the wheel-rail lateral forces at two sides of the wheelset are difficult to separate, a new derailment criterion by combined use of wheelset derailment coefficient and wheel unloading ratio is proposed. To illustrate its effectiveness, the indirect method is applied to safety evaluation of rail- way vehicles in different scenarios, such as the cross wind safety of a high-speed train and the safety of a metro vehicle with hunting motions. Then, the feasibility of using this method to identify wheel-rail forces for low-floor light rail vehicles with resilient wheels is discussed. The values identified by this method is compared with that by Simpack simulation for the same low-floor vehicle, which shows a good coincidence between them in the time domain of the wheelset lateral force and the wheel-rail vertical force. In addition, use of the method to determine the high-frequency wheel-rail interaction forces reveals that it is possible to identify the high-frequency wheel-rail forces through the accelerations on the axle box.

关键词： Wheel-rail force Safety evaluation - Indirect method Union safety domain Wheelset derailment coefficient Hunting motions Cross wind Low-floor vehicle

Identifying the relationship between suspension parameters of underframe equipment and carbody modal frequency

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Journal of Modern Transportation 2014年第4期22卷 206-213页

作者： Guangbing Luo jing zeng Qunsheng Wang State Key Laboratory of Traction Power Southwest Jiaotong University

As a critical component of the railway vehicle, underframe equipment has a great influence on the ride comfort of railway vehicles due to their big mass and active vibration. Therefore, study on the relationship between suspension parameters of underframe equipment and the modal frequency of carbody is extremely crucial for con trolling the ride quality of railway vehicles. In this paper, a finite element model of the carbody was developed to investigate the effects of the suspension location, the mass of the suspension equipment, and the suspension frequency on the mode of the carbody. Then, the matching relationship between the suspension parameters and the modal frequency of the carbody was studied through the transfer function. In addition, roller rig tests were performed to verify the numerical simulation model of the carbody. The results show that the suspension parameters of the underframe equipment have a great influence on the mode of the carbody, especially for the frequency of the first bending mode. To improve the frequency of carbody highfrequency bending and reduce energy transfer, equipment with a large mass should be suspended toward the middle of the carbody. The weight of the equipment strongly affects the first bending frequency and energy transfer of the carbody. The frequency of heavy suspended equipment should be sufficiently low to increase the transmissibility of high frequencies and improve the vibration characteristics of the carbody. Although the bending frequency of the carbody can be improved effec tively by increasing the suspension stiffness of thesuspension equipment, in order to reduce carbody vibration effectively, the suspension frequency of the equipment should be slightly lower than the carbody bending frequency.

关键词： Underframe equipment Suspension parameters Modal frequency Carbody Bending frequency Suspension types

Non-symmetrical levee breaching processes in a channel bend due to overtopping

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International Journal of Sediment Research 2018年第2期33卷 208-215页

作者： Songbai Wu Minghui Yu Hongyan Wei Yanjie Liang jing zeng State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Institute of Earth Surface System and Hazards Northwest University Yellow River Engineering Consulting Co. Ltd.

A series of experiments were done to reveal the overtopping breaching process of non-cohesive and cohesive levees in a U-bend flume. The flood hydrograph and breaching geometry were measured and analyzed in detail. The results show that the levee breaching processes can be briefly divided into four stages: slope erosion, longitudinal headward gully-cutting, lateral erosion, and relative stabilization. For non-cohesive levees, non-symmetrical lateral development of the breach occurs throughout the four stages, and the final non-symmetrical coefficient is approximately 2.2-2.6. Larger flow discharge or higher water level can accelerate the breaching process, while coarser sands tend to accelerate the process initially but depress the process at the end. The fluvial erosion rate of a non-cohesive breach shows a power-function relation with the excess wall shear stress. For cohesive levees, a plateau forms in the breach partially blocking the flow in the first two stages. The breach flow is approximately perpendicular to the levee body, and, thus, the erosion rates of the two breach sides are almost the ***-symmetrical lateral development mainly occurs in the third stage when the deep gully forms. The final non-symmetrical coefficient is approximately 2.7-3.3. It is expected that these findings can provide a valuable experimental dataset and a theoretical basis for breach closure and flood alleviation.

关键词： Overtopping Levee breach Hydrodynamic model Flume experiment

Paleoseismologic record of earthquakes along the Wuzunxiaoer section of the Altyn Tagh fault and its implication for cascade rupture behavior

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Science China Earth Sciences 2020年第1期63卷 93-107页

作者： Zhaode YUAN jing LIU-zeng You ZHOU Zhigang LI Heng WANG Wenqian YAO Longfei HAN State Key Laboratory of Earthquake Dynamics Institute of GeologyChina Earthquake AdministrationBeijing 100029China Institute of Geomechanics Chinese Academy of Geological SciencesBeijing 100081China School of Earth Sciences and Engineering Sun Yat-Sen UniversityGuangzhou 510275China

The Altyn Tagh fault is one of the few great active strike-slip faults in the world. The recurrence characteristics of paleoearthquakes on this fault are still poorly understood due to the lack of paleoseismic records recorded in high-resolution strata. We document a paleoseismic record in a pull-apart basin along the Wuzunxiaoer section of the central Altyn Tagh *** high-resolution strata recorded abundant seismic deformations and their sedimentary responses. Four earthquakes are identified based on event evidence in the form of open fissures, thickened strata, angular unconformities, and folds. The occurrence times of the four events were constrained using radiocarbon dating. Event W1 occurred at AD1220–1773, events W2 and W3 occurred between 407 and 215 BC, and event W4 occurred slightly earlier at 1608–1462 BC, indicating clustered recurrence characteristics. A comparison of the earthquake records along the Wuzunxiaoer section with other records along the Xorkoli section suggests that both sections ruptured during the most recent event.

关键词： Tibet Altyn Tagh fault Strike-slip fault Paleoearthquake Coseismic offset

Exploring the Far Side of Glycosyl Sulfoxide Activation Process

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Chinese Journal of Chemistry 2023年第4期41卷 383-391页

作者： Wei Chen Pinru Wu jing zeng jing Fang Zhiwen Liao Lei Cai Hao Wang Lingkui Meng Qian Wan Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation School of PharmacyHuazhong University of Science and Technology13 Hangkong RoadWuhanHubei430030 China Wuhan Union Hospital of China Huazhong University of Science and Technology1277 Jiefang AvenueWuhanHubei430022 China

The discovery of Kahne glycosylation forwards a big step in the carbohydrate *** an extensive series of studies,the precise mechanism of this powerful glycosylation is still not fully *** address these 30-year puzzles,the far side of Kahne glycosylation is explored in this *** a series of control and tracking experiments,a number of important intermediates including glycosyl oxo-sulfonium ion and sulfenic anhydride(Crich's intermediate)are suggested to be responsible for the complex reaction *** also reveals that in addition to the conventional ionic glycosylation pathway,a novel free radical pathway is very likely to contribute to the various side-and *** study provides further understanding of Kahne glycosylation,and it also sheds light on how to improve the efficiency of sulfoxide-based glycosylation reactions.

关键词： Carbohydrates Kahne glycosylation Radicals Reaction mechanisms Reactive intermediates

Non-Markovianity of an atom in a semi-infinite rectangular waveguide

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Chinese Physics B 2023年第3期32卷 102-110页

作者：曾静宋亚菊卢竞周兰 Key Laboratory of Low-Dimensional Quantum Structures and and Quantum Control of the Ministry of Education Department of Physics and Synergetic Innovation Center of Quantum Effects and ApplicationsKey Laboratory for Matter Microstructure and Function of Hunan ProvinceHunan Normal UniversityChangsha 410081China College of Physics and Electronic Engineering Hengyang Normal UniversityHengyang 421002China

We investigate the non-Markovianity(NM)of a waveguide QED with a two-level atom as the system and a semiinfinite rectangular waveguide as the environment,where the transverse magnetic(TM_(mn))modes define the quantum channels of guided *** perfect mirror imposed by the finite end exerts a retarded feedback mechanism to allow for information backflow,which leads to NM *** the energy separation of the atom far away from the cutoff frequencies of transverse modes,the delay differential equations are obtained with single-excitation initial in the *** attention is focused on the effects of multiple quantum channels involved in guiding photons on the degree of nonMarkovian *** asymptotic value of the non-Markovianity N_(1)can be found as the atom–mirror distance is large enough,however,the asymptotic value of N_(2)of the atom interacting with the effective double-modes is lower than that of the atom interacting with the effective *** also show that N_(1)is a constant,and the analytical expression for N_(2)is related to the parameters associated with the modes,which is related to the interference of the two modes.

关键词： open system non-Markovianity waveguide QED quantum information