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In Situ Synchrotron Radiation Techniques: Watching Deformation-induced Structural Evolutions of Polymers

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Chinese Journal of Polymer Science 2018年第10期36卷 1093-1102页

作者： liang-bin li National Synchrotron Radiation Lab Chinese Academy of Sciences Key Laboratory of Soft Matter Chemistry Anhui Provincial Engineering Laboratory of Advanced Functional Polymer Film University of Science and Technology of China

Synchrotron radiation （SR） provides highly brilliant light with tunable wavelength from hard X-ray to far infrared, on which scattering, spectroscopy and imaging techniques with high time and spatial resolutions have been developed for in situ study on biological system and materials like polymer. With examples on flow-induced crystallization of polymer, deformation of nanoparticle filler network in rubber composite and necking propagation in tensile stretch, current work attempts to demonstrate the advantages of in situ synchrotron radiation X-ray scattering, X-ray nano-CT and infrared imaging in the study of deformation-induced multi-scale structural evolutions of polymers. With time resolution up to sub-ms, synchrotron radiation is expected to play a great role in understanding non-equilibrium polymer physics under processing and service conditions, while high-throughput characterization platform based on synchrotron radiation opens the possibility to establish polymer Materials Genome database in processing parameter space within reasonable time, which can serve as the roadmap for industrial polymer processing and accelerate material innovation.

关键词： Synchrotron radiation techniques X-ray nano-CT Flow-induced crystallization Necking propagation Rubber nanocomposite

Multiscale computation on feedforward neural network and recurrent neural network

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Frontiers of Structural and Civil Engineering 2020年第6期14卷 1285-1298页

作者： bin li Xiaoying ZHUANG Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

Homogenization methods can be used to predict the effective macroscopic properties of materials that are heterogenous at micro-or *** existing methods for homogenization,computational homogenization is widely used in multiscale analyses of structures and *** computational homogenization suffers from long computing times,which substantially limits its application in analyzing engineering *** neural networks can be used to construct fully decoupled approaches in nonlinear multiscale methods by mapping macroscopic loading and microscopic *** homogenization methods for nonlinear material and implementation of offline multiscale computation are studied to generate data *** article intends to model the multiscale constitution using feedforward neural network(FNN)and recurrent neural network(RNN),and appropriate set of loading paths are selected to effectively predict the materials behavior along unknown *** to two-dimensional multiscale analysis are tested and discussed in detail.

关键词： multiscale method constitutive model feedforward neural network recurrent neural network

Spacecraft attitude maneuver control using two parallel mounted 3-DOF spherical actuators

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Chinese Journal of Aeronautics 2017年第1期30卷 419-425页

作者： li Guidan li Haike li bin School of Electrical and Information Engineering Tianjin University Tianjin 300072 China State Grid Tianjin Power Dongli Power Supply Branch Tianjin 300300 China

A parallel configuration using two 3-degree-of-freedom（3-DOF） spherical electromagnetic momentum exchange actuators is investigated for large angle spacecraft attitude ***, the full dynamic equations of motion for the spacecraft system are derived by the NewtonEuler method. To facilitate computation, virtual gimbal coordinate frames are established. Second,a nonlinear control law in terms of quaternions is developed via backstepping method. The proposed control law compensates the coupling torques arising from the spacecraft rotation, and is robust against the external disturbances. Then, the singularity problem is analyzed. To avoid singularities, a modified weighed Moore-Pseudo inverse velocity steering law based on null motion is proposed. The weighted matrices are carefully designed to switch the actuators and redistribute the control torques. The null motion is used to reorient the rotor away from the tilt angle saturation state. Finally, numerical simulations of rest-to-rest maneuvers are performed to validate the effectiveness of the proposed method.

关键词： Attitude maneuver Backstepping control Null motion Parallel configuration Singularity Spherical actuator

Multi-Vehicle Cooperative Positioning Based on Edge-Computed Multidimensional Scaling

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China Communications 2021年第6期18卷 53-63页

作者： bin Yang Rui Chen bin li Changle li State Key Laboratory of ISN Xidian UniversityXi’an 710071China Shaanxi Key Laboratory of Integrated and Intelligent Navigation Xi’an 710068China

As the basis of location-based services(LBS),positioning is one of the most essential parts in intelligent transportation systems(ITS).Although global positioning system(GPS)has been widely used in vehicle positioning,it can not achieve lane level positioning *** by the mature ranging technologies such as radar and ultra-wideband(UWB),several cooperative positioning(CP)methods have been proposed to enhance the accuracy and robustness of *** this paper,we proposed a twostage CP algorithm that combines multidimensional scaling(MDS)and Procrustes analysis for vehicles with GPS ***,the optimized MDS based on the scaling by majorizing a complicated function(SMACOF)algorithm is first proposed to get the relative coordinates of vehicles which can tackle measurements of different error distributions,then Procrustes analysis is carried out to transform the relative coordinates of vehicles to their absolute coordinates based on GPS *** the computations are performed at the mobile edge computing node(MECN)for the request of ultra-reliable and low latency communications(URLLC).Simulation results validate that the proposed algorithm can greatly improve the positioning accuracy and robustness for vehicles.

关键词： intelligent transportation systems(ITS) Internet of vehicles(IoV) multidimensional scaling(MDS) positioning Procrustes analysis

First-Principles Study of Field Emission from Zigzag Graphene Nanoribbons Terminated with Ether Groups

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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： Xin Chen bin li Department of Physics University of Science and Technology of China Hefei 230026 China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Hefei 230026 ChinaSynergetic Innovation Center of Quantum Information & Quantum Physics University of Science and Technology of China Hefei 230026 China

Field emission properties of zigzag graphenenanoribbons terminated with C-O-C ether groups (including cyclic and alternative ether groups at edge, denoted as ZGNR-CE and ZGNR-AE) are studied by adopting a self-consistent method based on density functional theory calculation. The results show that the field emissions of these two nanoribbons are dominated by states around Brillouin zone center and close to Fermi level. Because of lower work function, the ZGNR-CE can produce much stronger emission current than reconstructed zigzag graphenenanoribbon. The ZGNR-AE has nearly completely spin-polarized emission current, although its emission current is not strong enough. It is also found that under the lower E-field, the uniaxial strain can effectively modulate their emission currents but the spin polarization of ZGNR-AE keeps unchanged with the varied strain. The underlying mechanisms are revealed by combining the analyses of their work functions and band structures with edge dipole model.

关键词： Field emission Nanoribbon Ether group Density functional theory

Probabilistic-constrained robust secure transmission for energy harvesting over MISO channels

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Science China(Information Sciences) 2018年第2期61卷 65-76页

作者： bin li Zesong FEI School of Information and Electronics Beijing Institute of Technology

In this paper, we consider a system supporting simultaneous wireless information and power transfer(SWIPT), where the transmitter delivers private message to a destination receiver(DR) and powers to multiple energy receivers(ERs) with multiple single-antenna external eavesdroppers(Eves). We study secure robust beamformer and power splitting(PS) design under imperfect channel state information(CSI).The artificial noise(AN) scheme is further utilized at the transmitter to provide strong wireless security. We aim at maximizing the energy harvested by ERs subject to the transmission power constraint, a range of outage constraints concerning the signal-to-interference-plus-noise ratio(SINR) recorded at the DR and the Eves, as well as concerning the energy harvested at the DR. The energy harvesting maximization(EHM)problem is challenging to directly solve, we resort to Bernstein-type inequality restriction technique to reformulate the original problem as a tractable approximated version. Numerical results show that our robust beamforming scheme outperforms the beamforming scheme relying on the worst-case design philosophy.

关键词： secure communication wireless power transfer power splitting Bernstein-type inequality robust beamforming

Spatial-temporal modeling of initial COVID-19 diffusion: The cases of the Chinese Mainland and Conterminous United States

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Geo-Spatial Information Science 2021年第3期24卷 340-362页

作者： Daniel Griffith bin li Department of Geography&Environmental Studies Central Michigan UniversityMount PleasantMichiganUnited States School of Economic Political and Policy SciencesThe University of Texas at DallasRichardsonTexasUnited States

COVID-19 outbreaks in China in late December 2019,then in the United States(US)in early *** the initial wave of diffusion,the virus respectively took 14 and 33 days to spread across the provinces/states in the Chinese mainland and the coterminous US,during which there are 43%and 70%zero entries in the space-time series for China and US respectively,indicating a zero-inflated count process.A logistic growth curve as a function of the number of days since the first case appeared in each of these countries accurately portrays the national aggregate per capita rates of infection for *** paper presents two space-time model specifications,one based upon the generalized linear mixed model,and the other upon Moran eigenvector space-time filtering,to describe the spread of COVID-19 in the initial 19 and 58 days across the Chinese mainland and the coterminous US,*** from these case studies show both models shed new light on the role of spatial structures in COVID-19 diffusion,models that can forecast new cases in subsequent days.A principal finding is that describing the spatiotemporal diffusion of COVID-19 benefits from including a hierarchical structural component to supplement the commonly employed contagion component.

关键词： COVID-19 contagion diffusion hierarchical diffusion moran eigenvector spatial-time filtering random effects

MCS-based quantile value approach for reliability-based design of tunnel face support pressure

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Underground Space 2024年第5期18卷 187-198页

作者： bin li Changxing Wang Hong li Department of Road and Bridge Engineering School of Transportation and Logistics EngineeringWuhan University of TechnologyWuhan 430063China Hubei Highway Engineering Research Center Wuhan 430063China

This paper develops a new approach for reliability-based design(RBD)of tunnel face support pressure from a quantile value perspective.A surrogate model is constructed to calculate the collapse pressures of the random samples generated by a single run of Monte Carlo simulation(MCS).The cumulative distribution function(CDF)of the collapse pressure is then obtained and the support pressure aiming at a target failure probability is chosen as the upper quantile value of the collapse *** proposed approach does not require repetitive reliability analyses compared to the existing ***,a direct relationship between the target failure probability and the required support pressure is *** illustrative example is used to demonstrate the implementation *** accuracy of the reliability-based support pressures is verified by direct MCS incorporating with three-dimensional numerical ***,the influencing factors,including the sample size of MCS,the correlation coefficient between random variables,the choice of experimental points,and the surrogate model,are *** method can play a complementary role to available approaches due to its advantages of simplicity and efficiency.

关键词： Tunnel face stability Support pressure Reliability-based design Response surface method Monte Carlo simulation

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基于LSM树的视频数据扩容存储系统设计

电子设计工程 2025年第1期33卷 31-35页

作者：李斌刘思尧国网宁夏电力有限公司信息通信公司宁夏银川750000 宁夏信通网络科技有限公司宁夏银川750000

针对视频清晰度过高导致存储容量不足以及处理耗时长的问题,设计基于LSM树的视频数据扩容存储系统。利用EMCX4-480磁盘阵列储存备份数据,使用FPGA实现数据缓存管理与控制。应用LSM树控制存储过程中出现的延迟问题,并通过分割机制计算数... 详细信息

针对视频清晰度过高导致存储容量不足以及处理耗时长的问题,设计基于LSM树的视频数据扩容存储系统。利用EMCX4-480磁盘阵列储存备份数据,使用FPGA实现数据缓存管理与控制。应用LSM树控制存储过程中出现的延迟问题,并通过分割机制计算数据节点的分割存储数量,由此完成系统扩容。利用LSM树组织视频数据,应用概率描述存储期望值,实现视频数据扩容存储。由实验结果可知,该系统能够将所有视频数据存储在系统中,且数据存储最大耗时为179 ms,能够达到在短时间内实现全部视频数据有效存储的目的。

关键词： LSM树视频数据扩容存储数据重叠系统扩容