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SPICE modeling of memristors with multilevel resistance states

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Chinese Physics B 2012年第9期21卷 594-600页

作者：方旭东唐玉华吴俊杰 National Laboratory for Parallel and Distributed Processing School of ComputerNational University of Defense Technology department of computer Science and technology School of ComputerNational University of Defense Technology

With CMOS technologies approaching the scaling ceiling, novel memory technologies have thrived in recent years, among which the memristor is a rather promising candidate for future resistive memory （RRAM）. Memristor＇s potential to store multiple bits of information as different resistance levels allows its application in multilevel cell （MCL） tech- nology, which can significantly increase the memory capacity. However, most existing memristor models are built for binary or continuous memristance switching. In this paper, we propose the simulation program with integrated circuits emphasis （SPICE） modeling of charge-controlled and flux-controlled memristors with multilevel resistance states based on the memristance versus state map. In our model, the memristance switches abruptly between neighboring resistance states. The proposed model allows users to easily set the number of the resistance levels as parameters, and provides the predictability of resistance switching time if the input current/voltage waveform is given. The functionality of our models has been validated in HSPICE. The models can be used in multilevel RRAM modeling as well as in artificial neural network simulations.

关键词： memristor multilevel cell SPICE model

A Specific-Targeting Asymmetric Group Key Agreement for Cloud Computing

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Chinese Journal of Electronics 2018年第4期27卷 866-872页

作者： TAN Yu'an ZHENG Jiamin ZHANG Qikun ZHANG Xiaosong LI Yuanzhang ZHANG Quanxin School of computer Science and technology Beijing Institute of Technology Institute of computer and Communication Engineering Zhengzhou University of Light Industry department of computer Science and technology Tangshan University

When the information is exchanged and transmitted among the group members in mobile cloud environment, the group members may distribute different security domains. The information exchanged among group members may have different secret levels in this environment. When a person has some secret information, he only wants to share these information with some people who have the appropriate level of security permissions, other than all the members in the group. Aiming at these needs,we propose a flexible Asymmetric group key agreement(AGKA) protocol that information exchange and transmission are specific-targeting. The paper adopts bilinear mapping and two-way anonymous authentication technology to hide personal identity authentication information, and uses storage and computing migration technology to reduce the resource consumption of mobile terminal, and also proposes the secret key factor oriented extraction and combinations technology to achieve multi-level three-dimensional complex space security information exchange requirements and meet the lightweight computing. The analysis proves that the protocol has good safety performance and low resource consumption.

关键词： Asymmetric group key agreement(AGKA) Specific-targeting information exchange Key self-certified Mobile cloud

A High-Performance Hierarchical Snapshot Scheme for Hybrid Storage Systems

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Chinese Journal of Electronics 2018年第1期27卷 76-85页

作者： YU Xiao TAN Yu'an ZHANG Changyou LIANG Chen Khaled AOURRA ZHENG Jun ZHANG Quanxin School of computer Science and technology Beijing Institute of Technology department of computer Science and technology Shandong University of Technology Institute of Software Chinese Academy of Science

With the increased snapshot operations(creation or deletion), the performance of storage system will degrade severely whether in Copy on write(COW)or Redirect on write(ROW). This paper presents a novel snapshot scheme which could use of storage resources effectively and keep the historical data accurately for SSDHDD-hybrid storage system. SSD(source volume) stores all the active data and executes read/write operations without responding to snapshot operations. In contrast,HDDs(snapshot volume) store the writing data sequentially in the form of logs and are responsible for backup and snapshot operations. In this way, the hybrid storage system can get the high throughput power via SSD even the snapshot functions are active and HDDs can keep pace with the high Input/Output operations per second(IOPS)capability of the SSD. Logs are combined and kept in a separate image volume by the controller. So, fine-grained Recovery point objective(RPO) and good Recovery time objective(RTO) can be achieved. Experiment results show that the prototype can achieve excellent I/O performance while snapshot operations are active and consume a few extra storage space.

关键词： Hybrid disk array Snapshot Copy on write(COW) Redirect on write(ROW) Recovery point objective(RPO) Recovery time objective(RTO)

Doping effect of rare-earth(lanthanum, neodymium and gadolinium) ions on structural,optical, dielectric and magnetic properties of copper nanoferrites

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Journal of Rare Earths 2018年第12期36卷 1299-1309页

作者： R. Rajesh Kanna K. Sakthipandi S.M.Seeni Mohamed Aliar Maraikkayar N. Lenin M. Sivabharathy department of Physics Sethu Institute of Technology department of computer Science and Engineering Sethu Institute of Technology

Copper and rare earth-doped(RE = La, Gd, Nd) CuFe1.85RE0.15O4nano ferrites were prepared using the so nochemical method. The effective doping of rare-earth(La3+, Nd3+, Gd3+) ions with copper nanoferrites was confirmed by X-ray diffraction. The tetrahedral and octahedral sites of the nano ferrites were identified through the Fourier transform infrared spectra. The doping of rare-earth elements enhances the optical bandgap energy of the nanoferrites that are observed through Ultraviolet-DRS spectra. The oxidation state of the elements Cu 2 p, La 3 d, Nd 3 d, Gd 3 d, Fe 2 p and O 1 s was analyzed. Scanning electron microscopy images indicate a spherical morphology with agglomeration to some elongate. The values of dielectric constant and conductivity decrease considerably due to doping rare-earth ions in copper nanoferrites. Low saturation magnetization and high coercivity values of rare earth-doped copper nanoferrites are observed from the typical hysteresis curves.

关键词： Nanoferrites Optical properties Dielectric response Magnetic measurements Rare earths

Surface-to-air missile sites detection agent with remote sensing images

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Science China(Information Sciences) 2021年第9期64卷 232-234页

作者： Feng LIU Jihong ZHU Wufan WANG Minchi KUANG department of computer Science and technology Tsinghua University

Improvement and development in satellite and aerial photography have resulted in the rapid growth of the quantity and quality of remote sensing images, which are commonly used in military intelligence gathering, navigation, damage assessment, surveying, and mapping. Finding military facilities such as surface-to-air missile sites(SAMSs) from massive amounts of high-resolution remote sensing images,

关键词： Information Systems and Communication Service

Quaternion Kernel Fisher Discriminant Analysis for Feature-Level Multimodal Biometric Recognition

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Chinese Journal of Electronics 2020年第6期29卷 1085-1092页

作者： WANG Zhifang ZHEN Jiaqi ZHU Fuzhen HAN Qi department of Electronic Engineering Heilongjiang University department of computer Science and technology Harbin Institute of Technology

Quaternion kernel Fisher discriminant analysis(QKFDA) is proposed for feature level multimodal biometric *** quaternion division ring,QKFDA extracts the most discriminative information from the quaternion fusion feature sets by maximizing the betweenclass variance while minimizing the within-class variance.A complete two-phases framework of QKFDA is developed:Quaternion kernel principal component analysis(QKPCA)plus Quaternion linear discriminant analysis(QLDA).Two experiments are designed:experiment Ⅰ fuses four different features of face and plamprint,experiment Ⅱ fuses three different features of face,plamprint and *** experimental results show that QKFDA is superior to both traditional feature fusion methods(series rule and weighted sum rule)and other quaternion feature fusion methods(QPCA,QFDA,QLPP and QKPCA).

关键词： biometrics (access control) face recognition feature extraction image fusion principal component analysis plamprint feature face feature fusion quaternion feature fusion methods QLDA quaternion linear discriminant analysis QKPCA QLPP QFDA QPCA quaternion kernel principal component analysis quaternion kernel Fisher discriminant analysis quaternion fusion feature sets discriminative information quaternion division ring feature level multimodal biometric recognition QKFDA Quaternion division ring Quaternion kernel Fisher discriminant analysis (QKFDA) Multimodal biometrics Feature fusion

Hover control of a thrust-vectoring aircraft

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Science China(Information Sciences) 2015年第7期58卷 200-204页

作者： KUANG MinChi ZHU JiHong department of computer Science and technology Tsinghua University

In this paper, the hover control method of a thrust-vectoring aircraft is discussed, which is the first step to realize vertical takeoff and landing(VTOL) as a tail-sitter. To avoid the gimbal lock problem,vertical Euler angles are used and a new calculation method of them is presented. The attitude controller switches between horizon mode and vertical mode, with a specially designed switchable control ***/constant acceleration approximation is used for attitude control, which aims to get quick response and prevent overshooting at the same time. Special proportion integral derivative(PID) controller with anti-torque counteraction is proposed to generate servo angles. Experimental results verify the effectiveness of the proposed control method.

关键词： hover control thrust-vectoring aircraft tail-sitter vertical takeoff and landing(VTOL) vertical Euler angles

Multi-objective evaluation and optimization on trustworthy computing

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Science China(Information Sciences) 2016年第10期59卷 242-244页

作者： Chuang LIN Chao XUE department of computer Science & technology Tsinghua University

TC(trustworthy computing)is *** the appearance of TCB in TCSEC in the1980s and the following TDI and TNI,to the establishment of TCPA and the reorganization of TCG in April 2003,discussion and research on TC have lasted more than 30 years both in academia and *** are plenty of achievements and understanding in the exploration of software and networking trustworthiness,and they have been continuously developing and evolving with the appearance of new technology and environment.

关键词： MOP Multi-objective evaluation and optimization on trustworthy computing Figure

Helmholtz Solving and Performance Optimization in Global/Regional Assimilation and Prediction System

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Tsinghua Science and technology 2021年第3期26卷 335-346页

作者： Jianqiang Huang Wei Xue Haodong Bian Wenxin Yan Xiaoying Wang Wenguang Chen department of computer Science and technology Tsinghua UniversityBeijing 100084China department of computer technology and Applications Qinghai UniversityXining 810016China

Despite efficient parallelism in the solution of physical parameterization in the Global/Regional Assimilation and Prediction System(GRAPES),the Helmholtz equation in the dynamic core,with the increase of resolution,can hardly achieve sufficient parallelism in the solving process due to a large amount of communication and irregular *** this paper,optimizing the Helmholtz equation solution for better performance and higher efficiency has been an urgent *** optimization scheme for the parallel solution of the Helmholtz equation is proposed in this ***,the geometrical multigrid optimization strategy is designed by taking advantage of the data anisotropy of grid points near the pole and the isotropy of those near memory equator in the Helmholtz equation,and the Incomplete LU(ILU)decomposition preconditioner is adopted to speed up the convergence of the improved Generalized Conjugate Residual(GCR),which effectively reduces the number of iterations and the computation *** overall solving performance of the Helmholtz equation is improved by thread-level parallelism,vectorization,and reuse of data in the *** experimental results show that the proposed optimization scheme can effectively eliminate the bottleneck of the Helmholtz equation as regards the solving *** the test results on a 10-node two-way server,the solution of the Helmholtz equation,compared with the original serial version,is accelerated by 100,with one-third of iterations reduced.

关键词： Global/Regional Assimilation and Prediction System(GRAPES) Helmholtz equation Generalized Conjugate Residual(GCR) performance optimization Incomplete LU(ILU)