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Kohn–Sham time-dependent density functional theory with Tamm–Dancoff approximation on massively parallel GPUs

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npj computational Materials 2023年第1期9卷 1556-1567页

作者： Inkoo Kim Daun Jeong Won-Joon Son Hyung-Jin Kim Young Min Rhee Yongsik Jung Hyeonho Choi Jinkyu Yim Inkook Jang Dae Sin Kim Innovation center Samsung ElectronicsHwaseong 18448Republic of Korea Department of Chemistry Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Samsung Advanced Institute of technology Samsung ElectronicsSuwon 16678Republic of Korea

We report a high-performance multi graphics processing unit(GPU)implementation of the Kohn–Sham time-dependent density functional theory(TDDFT)within the Tamm–Dancoff *** algorithm on massively parallel computing systems using multiple parallel models in tandem scales optimally with material size,considerably reducing the computational wall time.A benchmark TDDFT study was performed on a green fluorescent protein complex composed of 4353 atoms with 40,518 atomic orbitals represented by Gaussian-type functions,demonstrating the effect of distant protein residues on the *** the largest molecule attempted to date to the best of our knowledge,the proposed strategy demonstrated reasonably high efficiencies up to 256 GPUs on a custom-built state-of-the-art GPU computing system with Nvidia A100 *** believe that our GPU-oriented algorithms,which empower first-principles simulation for very large-scale applications,may render deeper understanding of the molecular basis of material behaviors,eventually revealing new possibilities for breakthrough designs on new material systems.

关键词： GPUs graphics massive

The initial stages of Li_(2)O_(2) formation during oxygen reduction reaction in Li-O_(2) batteries:The significance of Li_(2)O_(2) in charge-transfer reactions within devices

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Journal of Energy Chemistry 2024年第1期88卷 223-231,I0006页

作者： Daniela M.Josepetti Bianca P.Sousa Simone A.J.Rodrigues Renato G.Freitas Gustavo Doubek Advanced Energy Storage Division LABCenter for Innovation on New EnergiesSchool of Chemical EngineeringUniversity of CampinasAv Albert Einstein 50013083-852CampinasSPBrazil Institute of Physics&Department of Chemistry Laboratory of Computational MaterialsFederal University of Mato Grosso78060-900CuiabáMTBrazil

Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion ***,this theoretical characteristic has not yet been converted into a real device with high *** with air contamination,metallic lithium reactivity,and complex discharge and charge reactions are the main issues for this technology.A fast and reversible oxygen reduction reaction(ORR)is crucial for good performance of secondary batteries',but the partial knowledge of its mechanisms,especially when devices are concerned,hinders further *** this perspective,the present work uses operando Raman experiments and electrochemical impedance spectroscopy(EIS)to assess the first stages of the discharge processes in porous carbon electrodes,following their changes cycle by cycle at initial operation.A growth kinetic formation of the discharge product signal(Li_(2)O_(2))was observed with operando Raman,indicating a first-order reaction and enabling an analysis by a microkinetic *** solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time *** the time constant for the anode interface reveals to remain relatively constant after the first discharge,its surface seemed to be more *** model indicated that the reaction occurs at the Li_(2)O_(2) surface,decreasing the associated resistance during the initial discharge ***,the growth of Li_(2)O_(2) forms a hetero-phase between Li_(2)O_(2)/electrolyte,while creating a more compact and homogeneous on the Li_(2)O_(2)/cathode *** methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis.

关键词： Li-O_(2)battery Operando Raman analysis Equivalent circuit modeling Time-constant distribution

Efficient coherent detection of maneuvering targets based on location rotation transform and non-uniform fast Fourier transform

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Frontiers of Information technology & Electronic Engineering 2020年第8期21卷 1251-1266页

作者： Ke JIN Tao LAI Yan-li QI Jie HUANG Yong-jun ZHAO National Digital Switching system Engineering and Technological research center Zhengzhou 450001China School of Electronics and Communication Engineering Sun Yat-Sen UniversityGuangzhou 510000China Anhui Institute of Quality and Standardization Hefei 230000China

Long-term coherent integration can remarkably improve the ability of detection and motion parameter estimation of radar for maneuvering ***,the linear range migration,quadratic range migration(QRM),and Doppler frequency migration within the coherent processing interval seriously degrade the detection and estimation ***,an efficient and noise-resistant coherent integration method based on location rotation transform(LRT)and non-uniform fast Fourier transform(NuFFT)is *** is corrected by the second-order keystone *** the relationship between the rotation angle and Doppler frequency,a novel phase compensation function is *** parameters can be rapidly estimated by LRT and *** with several representative algorithms,the proposed method achieves a nearly ideal detection performance with low computational ***,experiments based on measured radar data are conducted to verify the proposed algorithm.

关键词： Coherent integration Maneuvering target Parameter estimation Location rotation transform(LRT) Non-uniform fast Fourier transform(NuFFT)

A robust protocol to compute wind load coefficients of telecommunication towers and antennas using numerical simulation for risk and resilience assessment

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Resilient Cities and Structures 2024年第1期3卷 66-83页

作者： Mohanad Khazaali Liyang Ma Keivan Rokneddin Matteo Mazzotti Paolo Bocchini research Engineer Extreme Event Solutions at VeriskLafayette City CenterBostonMA 02111USA Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090PR China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information technology Harbin Institute of TechnologyHarbin 150090PR China Senior research Scientist RenaissanceRe Risk SciencesUSA research Associate P.M.Rady Department of Mechanical EngineeringUniversity of Colorado Boulder1111 Engineering Dr UCB 427BoulderCO 80309USA Professor Dept.of Civil and Environmental EngineeringLehigh University117 ATLSS DrBethlehemPA 18015-4729.USA Director Catastrophe Modeling CenterLehigh UniversityBethlehemPAUSA

An accurate estimation of wind loads on telecommunication towers is crucial for design,as well as for perform-ing reliability,resilience,and risk *** particular,drag coefficient and interference factor are the most significant factors for wind load *** tunnel tests and computational fluid dynamics(CFD)are the most appropriate methods to estimate these *** wind tunnel tests are generally preferred in practice,they require dedicated facilities and personnel,and can be expensive if multiple configurations of tower panels and antennas need to be tested under various wind directions(e.g.,fragility curve development for system resilience analysis).This paper provides a simple,robust,and easily accessible CFD protocol with widespread applicability,offering a practical solution in situations where wind tunnel testing is not feasible,such as complex tower configurations or cases where the cost of running experiments for all the tower-antennas configurations is prohibitively *** turbulence models,structural and fluid boundary conditions and mesh types are tested to provide a streamlined CFD modeling strategy that shows good convergence and balances accuracy,computational time,and *** protocol is calibrated and validated with experimental studies available in the *** demonstrate the capabilities of the protocol,three lattice tower panels and antennas with different configurations are analyzed as *** protocol successfully estimates the drag and lateral wind loads and their coefficients under different wind *** differences are observed between the esti-mated wind loads with this protocol and those computed by a simple linear superposition used in most practical applications,indicating the importance of tower-antenna ***,as expected,the wind loads recom-mended by design codes overestimate the simulated *** importantly,the telecommunication design codes inadequate

关键词： Generalized CFD protocol Lattice tower Tower panel Microwave antenna Wind coefficients Tower-antenna interaction

A TWO-GRID FINITE ELEMENT APPROXIMATION FOR NONLINEAR TIME FRACTIONAL TWO-TERM MIXED SUB-DIFFUSION AND DIFFUSION WAVE EQUATIONS

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Journal of computational Mathematics 2022年第6期40卷 936-954页

作者： Yanping Chen Qiling Gu Qingfeng Li Yunqing Huang School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China School of Mathematics and computational Science Xiangtan UniversityXiangtan 411199China

In this paper,we develop a two-grid method(TGM)based on the FEM for 2D nonlinear time fractional two-term mixed sub-diffusion and diffusion wave equations.A two-grid algorithm is proposed for solving the nonlinear system,which consists of two steps:a nonlinear FE system is solved on a coarse grid,then the linearized FE system is solved on the fine grid by Newton iteration based on the coarse *** fully discrete numerical approximation is analyzed,where the Galerkin finite element method for the space derivatives and the finite difference scheme for the time Caputo derivative with orderα∈(1,2)andα1∈(0,1).Numerical stability and optimal error estimate O(h^(r+1)+H^(2r+2)+τ^(min{3−α,2−α1}))in L^(2)-norm are presented for two-grid scheme,where t,H and h are the time step size,coarse grid mesh size and fine grid mesh size,***,numerical experiments are provided to confirm our theoretical results and effectiveness of the proposed algorithm.

关键词： Two-grid method Finite element method Nonlinear time fractional mixed sub-diffusion and diffusion-wave equations L1-CN scheme Stability and convergence

基于Seed-PCG法的列车-轨道-地基土三维随机振动GPU并行计算方法

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Journal of Central South University 2024年第1期31卷 302-316页

作者：朱志辉冯杨杨啸李昊邹有 National Engineering research center of High-speed Railway Construction technology Changsha 410075China School of Civil Engineering Central South UniversityChangsha 410075China School of Computer Science and Engineering Center South UniversityChangsha 410083China Information and Network center Central South UniversityChangsha 410083China

为了解决列车-轨道-地基土三维有限元模型随机多样本计算效率低的问题,本文提出了一种基于Seed-PCG法的高效并行计算方法。基于有限元法和虚拟激励法建立轨道不平顺激励下的三维列车-轨道-地基土耦合随机振动分析模型;针对车致地基土随... 详细信息

为了解决列车-轨道-地基土三维有限元模型随机多样本计算效率低的问题,本文提出了一种基于Seed-PCG法的高效并行计算方法。基于有限元法和虚拟激励法建立轨道不平顺激励下的三维列车-轨道-地基土耦合随机振动分析模型;针对车致地基土随机振动分析产生的多右端项线性方程组求解问题,采用Seed-PCG方法进行求解。通过PCG方法求解种子系统得到的Krylov子空间进行投影,以改进其余线性方程组的初始解和对应的初始残量,有效提高了PCG法的收敛速度,最后,在MATLABCUDA混合平台上开发了并行计算程序。数值算例表明:相同计算平台下的该方法相比多点同步算法获得了104.2倍的加速;相比PCG法逐个求解方案减少了18%的迭代次数,获得了1.21倍的加速。

关键词： Seed-PCG法多右端项线性方程组随机振动 GPU并行计算列车-轨道-地基土耦合模型

Applying Stack Bidirectional LSTM Model to Intrusion Detection

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Computers, Materials & Continua 2020年第10期65卷 309-320页

作者： Ziyong Ran Desheng Zheng Yanling Lai Lulu Tian School of Computer Science Research Center for Cyber SecuritySouthwest Petroleum UniversityChengdu610500China Brunel University London UxbridgeMiddlesexUB83PHUK

Nowadays,Internet has become an indispensable part of daily life and is used in many *** to the large amount of Internet traffic,computers are subject to various security threats,which may cause serious economic losses and even endanger national *** is hoped that an effective security method can systematically classify intrusion data in order to avoid leakage of important data or misuse of *** machine learning technology matures,deep learning is widely used in various *** deep learning with network security and intrusion detection is the current *** this paper,the problem of data classification in intrusion detection system is *** propose an intrusion detection model based on stack bidirectional long short-term memory(LSTM),introduce stack bidirectional LSTM into the field of intrusion detection and apply it to the intrusion *** order to determine the appropriate parameters and structure of stack bidirectional LSTM network,we have carried out experiments on various network structures and parameters and analyzed the experimental *** classic KDD Cup’1999 dataset was selected for experiments so that we can obtain convincing and comparable *** results derived from the KDD Cup’1999 dataset show that the network with three hidden layers containing 80 LSTM cells is superior to other algorithms in computational cost and detection performance due to stack bidirectional LSTM model’s ability to review time and correlate with connected records *** experiment shows the effectiveness of stack bidirectional LSTM network in intrusion detection.

关键词： Stack bidirectional LSTM KDD Cup’1999 intrusion detection systems machine learning recurrent neural network

Simulation Method of Dynamic Characteristics of Turbine Flow Sensor

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Instrumentation 2021年第3期8卷 1-15页

作者： GUO Suna JI Zengqi LIU Xu WANG Fan ZHAO Ning FANG Lide College of Quality and Technical Supervision Hebei UniversityBaodingHebei071002China National&Local Joint Engineering research center of Metrology Instrument and system BaodingHebei071002China Hebei Key Laboratory of Energy Metering and Safety Testing technology Hebei UniversityBaoding071002China

computational Fluid Dynamics(CFD)simulation is one of the important methods to study the performance and influencing factors of turbine flow *** to the working characteristics of the turbine flow sensor,the passive simulation method based on the six degrees of freedom(6-DOF)model and dynamic mesh is proposed in this *** reliability of the simulation method is verified by steady-state experiments and unsteady-state *** results show that the trend of meter factor with flow rate acquired from the simulation is close to the experimental results,and the deviation between the simulation result and the experiment result is low with a maximum deviation of 2.88%.In the unsteady simulation study,the impeller speed changes with the inlet velocity of the turbine flow sensor,which has a good *** passive simulation method can be used to predict the dynamic performance of the turbine flow sensor.

关键词： Turbine Flow Sensor CFD Dynamic Performance Unsteady-state Flow Simulation Method

Design and Evaluation of a Distributed Security Framework for the Internet of Things

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Journal of Signal and Information Processing 2022年第1期13卷 1-23页

作者： Kelechi G. Eze Cajetan M. Akujuobi The center of Excellence for Communication systems technology research (CECSTR) Department of Electrical Engineering Prairie View A & M University Prairie View USA

The adopters of IoT face challenges with the surging Internet-based attacks on their IoT assets and inefficiencies within the technology. Unfortunately, IoT is overly distributed, still evolving and facing implementation and security challenges. Given the above scenario, we argue that the IoT network should always be decentralized design, and security should be built by design. The paper is the design and construction of a decentralized IoT security framework, with the goal of making emerging IoT systems more resilient to attacks and supporting complex communication and resource sharing. The framework improves efficiency and scalability in IoT, exposes vulnerable subsystems and components as possible weak links to system compromise, and meets the requirements of a heterogeneous computing environment. Other features of the framework including efficient resource sharing, fault tolerance, and distributed storage support the Internet of Things. We discuss the design requirements and carry out the implementation of Proof of Concept and evaluation of our framework. Two underlying technologies: the actor model and the blockchain were used for the implementation. Our reason for choosing the actor model and blockchain is to compare its suitability for IoT integration in parallel. Hence, evaluation of the system is performed based on computational and memory efficiency, security, and scalability. We conclude from the evaluations that the actor-based implementation has better scalability than the block-chain-based implementation. Also, the blockchain seems to be computationally more intensive than the actors and less suitable for IoT systems.

关键词： Actor Model Blockchain Security Framework Internet of Things