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Scarring of Dirac fermions in chaotic billiards

Physical Review E 2012年第1期86卷 016702-016702页

作者： Xuan Ni Liang Huang Ying-Cheng Lai Celso Grebogi School of Electrical Computer and Energy Engineering Arizona State University Tempe Arizona 85287 USA Institute of Computational Physics and Complex Systems and Key Laboratory for Magnetism and Magnetic Materials of MOE Lanzhou University Lanzhou Gansu 730000 China Department of Physics Arizona State University Tempe Arizona 85287 USA Institute for Complex Systems and Mathematical Biology King's College University of Aberdeen Aberdeen AB24 3UE United Kingdom

Scarring in quantum systems with classical chaotic dynamics is one of the most remarkable phenomena in modern physics. Previous works were concerned mostly with nonrelativistic quantum systems described by the Schrödinger equation. The question remains outstanding of whether truly relativistic quantum particles that obey the Dirac equation can scar. A significant challenge is the lack of a general method for solving the Dirac equation in closed domains of arbitrary shape. In this paper, we develop a numerical framework for obtaining complete eigensolutions of massless fermions in general two-dimensional confining geometries. The key ingredients of our method are the proper handling of the boundary conditions and an efficient discretization scheme that casts the original equation in a matrix representation. The method is validated by (1) comparing the numerical solutions to analytic results for a geometrically simple confinement and (2) verifying that the calculated energy level-spacing statistics of integrable and chaotic geometries agree with the known results. Solutions of the Dirac equation in a number of representative chaotic geometries establish firmly the existence of scarring of Dirac fermions.

关键词： NONRELATIVISTIC quantum mechanics SCHRODINGER equation DIRAC equation FERMIONS BOUNDARY value problems RELATIVISTIC particles ENERGY levels (Quantum mechanics)

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Conductance fluctuations in graphene systems: The relevance of classical dynamics

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Physical Review B 2012年第24期85卷 245448-245448页

作者： Lei Ying Liang Huang Ying-Cheng Lai Celso Grebogi School of Electrical Computer and Energy Engineering Arizona State University Tempe Arizona 85287 USA Institute of Computational Physics and Complex Systems and Key Laboratory for Magnetism and Magnetic Materials of MOE Lanzhou University Lanzhou Gansu 730000 China Department of Physics Arizona State University Tempe Arizona 85287 USA Institute for Complex Systems and Mathematical Biology King's College University of Aberdeen Aberdeen AB24 3UE United Kingdom

Conductance fluctuations associated with transport through quantum-dot systems are currently understood to depend on the nature of the corresponding classical dynamics, i.e., integrable or chaotic. However, we find that in graphene quantum-dot systems, when a magnetic field is present, signatures of classical dynamics can disappear and universal scaling behaviors emerge. In particular, as the Fermi energy or the magnetic flux is varied, both regular oscillations and random fluctuations in the conductance can occur, with alternating transitions between the two. By carrying out a detailed analysis of two types of integrable (hexagonal and square) and one type of chaotic (stadium) graphene dot system, we uncover a universal scaling law among the critical Fermi energy, the critical magnetic flux, and the dot size. We develop a physical theory based on the emergence of edge states and the evolution of Landau levels (as in quantum Hall effect) to understand these experimentally testable behaviors.

关键词： FLUCTUATIONS (Physics) GRAPHENE QUANTUM dots MAGNETIC flux MAGNETIC fields

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Visualization of signalized intersections in driving simulator and validity of driving behaviors in virtual environments

Advances in Transportation Studies

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Advances in Transportation Studies 2012年第26期 17-28页

作者： Yan, X. Abdel-Aty, M. Guo, D. Radwan, E. MOE Key Laboratory for Transportation Complex Systems Theory and Technology Beijing Jiaotong University Beijing 100044 China Department of Civil and Environmental Engineering University of Central Florida Orlando FL 32816-2450 United States Computer Science Program College of Business Florida Gulf Coast University 10501 FGCU Boulevard South Fort Myers FL 33965-6565 United States Center for Advanced Transportation Systems Simulation University of Central Florida Orlando FL 32816-2450 United States

Visualization of highway traffic environments in virtual reality plays a key role on fidelity of simulation and validity of driving behaviors in driving simulator studies. This paper describes a procedure to replicate a signalized intersection with many complex features into a driving simulator's 3-D databases through building a graphical visual database, constructing a road motion database, and creating simulated traffic. The validity of the visualization was assessed via the comparison of the drivers' speeds in the simulator and the speed data at the real intersection. It was found that both speed data follow normal distributions and have equal means for each intersection approach;however, that the speeds measured in the driving simulator have a larger variability than those measured in the field. The users' subjective evaluation results indicated that 92% subjects could recognize the simulated intersection in the driving simulator experiment. Therefore, the strategy of geo-specific environment modeling would be useful for studying driving behaviors in virtual environments.

关键词： Visualization

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A reinforcement learning based tag recommendation

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作者： Ge, Feng He, Yi Liu, Jin Lv, Xiaoming Zhang, Wensheng Li, Yiqun State Key Laboratory of Software Engineering Computer School Wuhan University 430072 China Logistics Group Wuhan University 430072 China State Key Laboratory of Intelligent Control and Management of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China Baidu Inc. 100085 China

ISBN: (纸本)9783642256578

This paper proposes a reinforcement learning based tag recommendation algorithm to deal with the data sparseness that affects the performance stability of collaborative filtering algorithms. Our algorithm integrates user tags into traditional collaborative filtering algorithms and attaching importance to user interest shift in the process of user interest learning process. Empirical Cases of comparing with traditional collaborative filtering algorithms indicate that our recommend algorithm exhibits better performance competition. © 2011 Springer-Verlag Berlin Heidelberg.

关键词： Reinforcement learning

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A drum-buffer-rope based scheduling method for semiconductor manufacturing system

A drum-buffer-rope based scheduling method for semiconductor...

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2011 7th IEEE International Conference on Automation Science and engineering, CASE 2011

作者： Cao, Zhengcai Peng, Yazhen Wang, Yongji College of Information Science and Technology Beijing University of Chemical Technology Beijing 100029 China State Key Laboratory of Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an 710054 China State Key Laboratory of Computer Science Institute of Software Chinese Academy of Sciences Beijing 100190 China

ISBN: (纸本)9781457717307

Scheduling in semiconductor manufacturing system is an important task for the industries faced with a large amount of resource competitions. Effective scheduling can improve the overall system performance and customer satisfaction. In this paper, a scheduling method with the core of bottleneck equipment control is designed referring to Drum-Buffer-Rope (DBR) theory. In order to identify the main-bottleneck, the relative load which takes the feature of reentrance into consideration is applied. For the avoidance of local blocking, the management of sub-bottleneck is presented. As both releasing and dispatching are taken into account, a scheduling method based on the compound priority is formed. Finally, HP-24 semiconductor wafer fabrication is used as an example to demonstrate the effectiveness of the proposed method. © 2011 IEEE.

关键词： Customer satisfaction

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High-order MRF prior based bayesian deblurring

International Journal of Digital Content Technology and its ...

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International Journal of Digital Content Technology and its Applications 2011年第12期5卷 383-392页

作者： Zhao, Bo Zhang, Wensheng Liu, Jin Ding, Huan State Key Laboratory of Intelligent Control and Management of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China State Key Laboratory of Software Engineering Computer School Wuhan University China

A novel image deblurring method based on high-order non-local range Markov Random Field (NLR-MRF) prior is proposed in the paper. NLR-MRF provides an effective framework to model the statistical prior of natural images and leads to excellent performance in the application of image denoising and inpainting. Moreover, the framework will be extended to image deblurring in our work. Instead of commonly used maximum a-posteriori (MAP) estimation, which has several shortcomings, the high-order NLR-MRF prior is integrated into Bayesian minimum mean squared error (MMSE) estimation framework. Then, an efficient Gibbs sampling algorithm is adopted to compute MMSE estimation. The proposed method frees the user from determining regularization parameter beforehand, which relies on unknown noise level. We perform experiments on synthetic and real-world data to demonstrate the effectiveness of our method. Both quantitatively and qualitatively evaluations show superior or comparable results to the state-of-art deblurring methods.

关键词： Image denoising

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Region-based active contour with neighborhood information for image segmentation

International Journal of Digital Content Technology and its ...

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International Journal of Digital Content Technology and its Applications 2011年第10期5卷 322-329页

作者： Yang, Mingyu Liu, Jin Zhang, Wensheng Key Laboratory of Complex Systems and Intelligence Science Institute of Automation Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of software Engineering Computer School Wuhan University Wuhan 430072 China

Intensity inhomogeneous images, especially medical images, widely exist in real world. Considering that the existing methods can not solve intensity inhomogeneous images segmentation properly, this paper proposes a region-based active contour model with neighborhood information. Different from existing models using global region information, the new model incorporates local information of an image into a level set formulation. By defining a new energy functional for every pixel in the image domain and utilizing the information of neighborhoods, the proposed model has the ability to extract local details, thus can segment images with intensity inhomogeneity. We also present a new approximation of the Heaviside function and Dirac function. Experimental results demonstrate that the new model has desirable performance, which is more precise than the Chan-Vese model and much faster than the Piecewise Smooth model.

关键词： Image segmentation

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A drum-buffer-rope based scheduling method for semiconductor manufacturing system

A drum-buffer-rope based scheduling method for semiconductor...

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IEEE International Conference on Automation Science and engineering (CASE)

作者： Zhengcai Cao Yazhen Peng Yongji Wang College of Information Science and Technology Beijing University of Chemical Technology Beijing China State Key Laboratory of Manufacturing Systems Engineering Xi'an Jiaotong University Xian China State Key Laboratory of Computer Science Institute of Software Chinese Academy of Sciences (CAS) Beijing China

关键词： Job shop scheduling Distributed Bragg reflectors Object oriented modeling Semiconductor device modeling Workstations Fabrication Dispatching

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Abnormal electron paths induced by Klein tunneling in graphene quantum point contacts

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Physical Review B 2011年第3期84卷 035426-035426页

作者： Rui Yang Liang Huang Ying-Cheng Lai Celso Grebogi School of Electrical Computer and Energy Engineering Arizona State University Tempe Arizona 85287 USA Institute of Computational Physics and Complex Systems and Key Laboratory for Magnetism and Magnetic Materials of MOE Lanzhou University Lanzhou Gansu 730000 China Department of Physics Arizona State University Tempe Arizona 85287 USA Institute for Complex Systems and Mathematical Biology School of Natural and Computing Sciences King’s College University of Aberdeen Aberdeen United Kingdom

We study quantum transport in a general graphene system subject to external potential, a situation that can be expected in all kinds of future graphene-based electronic devices with quantum dots and quantum point contacts. We find that electrons tend to take on propagating paths due to Klein tunneling that have absolutely no counterpart in nonrelativistic quantum systems. Strikingly, such abnormal quantum paths can lead to an extreme type of fractal-like of conductance fluctuations, not seen previously in any quantum transport systems. This phenomenon has profound implications to the development of graphene based devices that require stable electronic properties.

关键词： ELECTRONIC systems QUANTUM electronics QUANTUM dots CATHODE rays LEPTONS (Nuclear physics)

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Interactive creation of Chinese calligraphy with the application in calligraphy education

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2011年 6530卷 112-121页

作者： Zhang, Xianjun Zhao, Qi Xue, Huanzhen Dong, Jun Software Engineering Institute East China Normal University Shanghai 200062 China International Education College Shanghai University of Finance and Economics Shanghai 200433 China Key Laboratory of Complex Systems and Intelligence Science Chinese Academy of Sciences Beijing 100080 China Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Suzhou 215125 China

ISBN: (纸本)9783642184512

Given a few tablet images of Chinese calligraphy, it is difficult to automatically create new Chinese calligraphy with better effects while keeping similar style. A semiautomatic creation scheme of Chinese calligraphy and its application in calligraphy education are proposed. First of all, the preprocessing, contour tracing and skeleton extraction are performed respectively on the images of original Chinese calligraphy characters. After that, strokes are extracted interactively. Then a statistical model is used to make stroke reforming. All strokes are stored separately in the stroke library. Finally, new Chinese calligraphy characters are created based on the structure of skeletons and right selection of reformed strokes from the stroke library. The experimental results show the created Chinese calligraphy characters look similar to the samples in the structure, however, with different effects. © 2011 Springer-Verlag Berlin Heidelberg.

关键词： Musculoskeletal system

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