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Observation of electron weak localization and correlation effects in disordered graphene

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Science China(Physics,Mechanics & Astronomy) 2009年第9期52卷 1293-1298页

作者： tan ChangLing tan zhenbing MA Li QU FanMing YANG Fan CHEN Jun LIU GuangTong YANG HaiFang YANG ChangLi LU Li Daniel Chee Tsui Laboratory Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China Laboratory of Microfabrication Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China

We have studied the electron transport properties of a disordered graphene sample, where the disorder was intentionally strengthened by Ga+ ion irradiation. The magneto-conductance of the sample exhibits a typical two-dimensional electron weak localization behavior, with electron-electron interaction as the dominant dephasing mechanism. The absence of electron anti-weak localization in the sample implies strong intersublattice and/or intervalley scattering caused by the disorders. The temperature and bias-voltage dependencies of conductance clearly reveal the suppression of conductance at low energies, indicating opening of a Coulomb gap due to electron-electron interaction in the disordered graphene sample.

关键词： graphene weak-localization electron-electron interaction power law

Synthesis of Isotopically-Labeled Graphite Films by Cold-Wall Chemical Vapor Deposition and Electronic Properties of Graphene Obtained from Such Films

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Nano Research 2009年第11期2卷 851-856页

作者： Weiwei Cai Richard D.Piner Yanwu Zhu Xuesong Li zhenbing tan Herman Carlo Floresca Changli Yang Li Lu M.J.Kim Rodney S.Ruoff Department of Mechanical Engineering and the Texas Materials Institute University of Texas at AustinAustinTX 78712USA Institute of Physics Chinese Academy of SciencesBeijing 100190China Department of Materials Science and Engineering University of Texas at DallasRichardsonTX 75083USA

We report the synthesis of isotopically-labeled graphite films on nickel substrates by using cold-wall chemical vapor deposition(CVD).During the synthesis,carbon from^(12)C-and^(13)C-methane was deposited on,and dissolved in,a nickel foil at high temperature,and a uniform graphite film was segregated from the nickel surface by cooling the sample to room *** and transmission electron microscopy,micro-Raman spectroscopy,and X-ray diffraction prove the presence of a graphite *** graphene films obtained from such isotopically-labeled graphite films by mechanical methods have electron mobility values greater than 5000 cm^(2)·V^(-1)·s^(-1)at low ***,such films exhibit the half-integer quantum Hall effect over a wide temperature range from 2 K to 200 K,implying that the graphite grown by this cold-wall CVD approach has a quality as high as highly oriented pyrolytic graphite(HOPG).The results from transport measurements indicate that^(13)C-labeling does not significantly affect the electrical transport properties of graphene.

关键词： Chemical vapor deposition(CVD) isotopically-labeled graphite graphene

Heilbronn's Problem of Eight Points in the Square

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Journal of Systems Science & Complexity 2022年第6期35卷 2452-2480页

作者： DEHBI Lydia ZENG zhenbing School of Software Engineering East China Normal UniversityShanghai 200062China Department of Mathematics Shanghai UniversityShanghai 200444China

In this work the authors consider the problem of optimally distributing 8 points inside a unit square so that the smallest area of the(38)triangles formed by them is *** computations are employed to reduce the problem... 详细信息

关键词： Global search Heilbronn’s problem optimal configuration smallest triangle’s area symbolic computations

Computing Sparse GCD of Multivariate Polynomials via Polynomial Interpolation

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Journal of Systems Science & Complexity 2018年第2期31卷 552-568页

作者： tanG Min LI Bingyu ZENG zhenbing School of Mathematics and Computing Science Guangxi Key Laboratory of Cryptography and Information Security Guilin University of Electronic Technology Guilin 541004 China Shanghai Key Laboratory of Trustworthy Computing East China Normal University Shanghai 200062 China. Email: ***@***. School of Mathematics and Statistics Northeast Normal University Changchun 130024 China. Department of Mathematics Shanghai University Shanghai 200444 China

The problem of computing the greatest common divisor（GCD） of multivariate polynomials, as one of the most important tasks of computer algebra and symbolic computation in more general scope, has been studied extensively since the beginning of the interdisciplinary of mathematics with computer science. For many real applications such as digital image restoration and enhancement,robust control theory of nonlinear systems, L1-norm convex optimization in compressed sensing techniques, as well as algebraic decoding of Reed-Solomon and BCH codes, the concept of sparse GCD plays a core role where only the greatest common divisors with much fewer terms than the original polynomials are of interest due to the nature of problems or data structures. This paper presents two methods via multivariate polynomial interpolation which are based on the variation of Zippel＇s method and Ben-Or/Tiwari algorithm, respectively. To reduce computational complexity, probabilistic techniques and randomization are employed to deal with univariate GCD computation and univariate polynomial interpolation. The authors demonstrate the practical performance of our algorithms on a significant body of examples. The implemented experiment illustrates that our algorithms are efficient for a quite wide range of input.

关键词： Ben-Or/Tiwari algorithm multivariate polynomial interpolation sparse GCD Zippel's algorithm.

Resultant Elimination via Implicit Equation Interpolation

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Journal of Systems Science & Complexity 2016年第5期29卷 1411-1435页

作者： tanG Min YANG Zhengfeng ZENG zhenbing Shanghai Key Laboratory of Trustworthy Computing East China Normal University Department of Mathematics Shanghai University

It is well known that resultant elimination is an effective method of solving multivariate polynomial equations. In this paper, instead of computing the target resultants via variable by variable elimination, the authors combine multivariate implicit equation interpolation and multivariate resultant elimination to compute the reduced resultants, in which the technique of multivariate implicit equation interpolation is achieved by some high probability algorithms on multivariate polynomial interpolation and univariate rational function interpolation. As an application of resultant elimination, the authors illustrate the proposed algorithm on three well-known unsolved combinatorial geometric optimization problems. The experiments show that the proposed approach of resultant elimination is more efficient than some existing resultant elimination methods on these difficult problems.

关键词： Elimination implicit equations interpolation resultants.

Adaptive robust cubature Kalman filtering for satellite attitude estimation

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Chinese Journal of Aeronautics 2018年第4期31卷 806-819页

作者： zhenbing QIU Huaming QIAN Guoqing WANG College of Automation Harbin Engineering University

This paper is concerned with the adaptive robust cubature Kalman filtering problem for the case that the dynamics model error and the measurement model error exist simultaneously in the satellite attitude estimation system. By using Hubel-based robust filtering methodology to correct the measurement covariance formulation of cubature Kalman filter, the proposed filtering algorithm could effectively suppress the measurement model error. To further enhance this effect and reduce the impact of the dynamics model error, two different adaptively robust filtering algorithms,one with the optimal adaptive factor based on the estimated covariance matrix of the predicted residuals and the other with multiple fading factors based on strong tracking algorithm, are developed and applied for the satellite attitude estimation. The quaternion is employed to represent the global attitude parameter, and three-dimensional generalized Rodrigues parameters are introduced to define the local attitude error. A multiplicative quaternion error is derived from the local attitude error to maintain quaternion normalization constraint in the filter. Simulation results indicate that the proposed novel algorithm could exhibit higher accuracy and faster convergence compared with the multiplicative extended Kalman filter, the unscented quaternion estimator, and the adaptive robust unscented Kalman filter.

关键词： Attitude estimation Cubature Kalman filter Multiple fading factors Optimal adaptive factor Robust filtering

Parallel computation of determinants of matrices with multivariate polynomial entries

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Science China(Information Sciences) 2013年第11期56卷 158-173页

作者： CHEN LiangYu ZENG zhenbing Shanghai Key Laboratory of Trustworthy Computing East China Normal University

In this paper we present an extension to the work of Bjrck et *** computing the determinants of matrices with univariate or bivariate polynomials as entries to multivariate *** algorithm supports parallel computation and has been implemented on a multi-core cluster computer *** show how to use our approach to calculate two unsolved problems,which arise from computational geometry optimization and electric power engineering,and analyze the time complexity as well as bits complexity.

关键词： determinant interpolation parallel algorithm

Effect of three-electrode plasma synthetic jet actuator on shock wave control

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Science China(Technological Sciences) 2017年第1期60卷 146-152页

作者： ZHOU Yan XIA ZhiXun LUO zhenbing WANG Lin Science and Technology on Scramjet Laboratory National University of Defense Technology Changsha 410073 China

A three-electrode high-energy plasma synthetic jet(PSJ) actuator was used for shock wave control. This actuator is an enhanced version of the two-electrode actuator as a high-voltage trigger electrode is added to increase the cavity volume and the input energy while retaining a relatively low disruptive voltage. The electrical properties were studied using current-voltage measurements, and the energy consumption was calculated. To assess the jet strength, the penetration of PSJ was compared with empirical values, and the results show that the momentum flux ratio of PSJ for a capacitance of 0.96, 1.6, and 3 μF was approximately equal to 0.6, 1.0, and 1.3, respectively. The interaction of PSJ with shock waves was acquired using high-speed shadowgraph imaging. The shock was generated by a 25° compression ramp in Mach 2 flow, and PSJ actuator was placed up-stream of the compression ramp. Under the action of PSJ, the strength of the shock was notably weakened, and the near-wall part of the shock was entirely eliminated. The results show the good control effect of the three-electrode high-energy PSJ in high-speed flow.

关键词： plasma synthetic jet three-electrode shock wave active flow control

A novel optimal design for an application-oriented synthetic jet actuator

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Chinese Journal of Aeronautics 2014年第3期27卷 514-520页

作者： Deng Xiong Xia Zhixun Luo zhenbing Wang Lin Science and Technology on Scramjet Laboratory National University of Defense Technology

The evaluation indicator for the performance of a synthetic jet actuator （SJA） is well-defined because of its various applications, which require optimal design to improve its performance and extend its field of application. This paper presents a novel approach to the optimal design of an SJA applied to enhance fuel/air mixture. It optimizes the combination of an actuator＇s geometric parameters by selecting the strength of vortex pairs as the evaluation indicator, coupled with orthogonal experiments and analysis of variance （AOV）. The results indicate that slot width is the most notable factor influencing the strength of vortex pairs, followed by cavity height and slot depth. The optimal value of the strength of vortex pairs increases by 32.5%over the experimental data of the base case, and more than 8.4%compared with the simulation results of the orthogonal experiments. It is concluded that the optimal method can effectively improve the performance of an SJA applied in mixing enhancement, reducing the test numbers and the associated design cycle and cost.

关键词： Analysis of variance Evaluation indicator Orthogonal experiment Strength of vortex pairs Synthetic jet