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Optical ultra-wideband pulse generation and distribution using a dual-electrode Mach-Zehnder modulator

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Chinese Optics Letters 2010年第2期8卷 138-141页

作者：李晶宁提纲裴丽祁春慧 Institute of Lightwave Technology Beijing Jiaotong University Key Lab of All Optical network and Advanced Telecommunication network of EMC Beijing Jiaotong University

A novel approach to generate and distribute ultra-wideband （UWB） pulses in optical domain is investigated. In this proposed scheme, a dual-electrode Mach-Zehnder modulator （DE-MZM） is biased at its quadrature point so as to realize the linear response. Then the intensity of output optical field can be assumed to the subtraction of two input Gaussian pulses. If the input Gaussian pulses are with the same sharp parameters but different time delays, a quasi-monocycle-waveform UWB signal can be generated. If the input Gaussian pulses are with different amplitudes and full-width at half-maximum （FWHM）, a quasi-doublet-waveform UWB signal can be generated. A transmission of the UWB signals through a 25-km single mode fiber is carried out successfully. The results in both temporal and frequency domains are also presented.

关键词： Light modulators Modulation Pulse generators Single mode fibers

Resource Intensity Aware Job Scheduling in A Distributed Cloud

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China Communications 2014年第A02期11卷 175-184页

作者： HUANG Daochao ZHU Chunge ZHANG Hong LIU Xinran national Computer network Emergency Response Technical Team Coordination Center of China (CNCERT or CNCERT/CC) No.A3 Yumin Road Chaoyang District Beijing China 100029

A Dominant Resource Fairness （DRF） based scheme for job scheduling in distributed cloud computing systems which was modeled as multi-job scheduling and multi-resource allocation coupling problem is proposed, where the resource pool is constructed from a large number of distributed heterogeneous servers, representing different points in the configuration space of resources such as processing, memory, storage and bandwidth. By introducing dominant resource share of jobs and virtual machines, the multi-job scheduling and multi-resource allocation joint mechanism significantly improves the cloud system＇s resource utilization, yet with a substantial reduction of job completion times. We show through experiments and case studies the superior performance of the algorithms in practice.

关键词： job scheduling resource allocation cloud computing dominant resource fairness

FINE:Future Internet iNnovation Environment

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China Communications 2015年第1期12卷 146-147页

作者： BI Jun Institute for network Sciences and Cyberspace Tsinghua University Department of Computer Science Tsinghua University Tsinghua national Laboratory for Information Science and Technology(TNList)

This article introduces FINE(Future Internet iNnovation Environment) project,which is supported by national High-tech R&D Program( "863" Program) of China.

关键词：互联网环境创新

Joint optimization of spectral efficiency for cell-free massive MIMO with network-assisted full duplexing

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Science China(Information Sciences) 2021年第8期64卷 156-171页

作者： Xinjiang XIA Pengcheng ZHU Jiamin LI Hao WU Dongming WANG Yuanxue XIN national Mobile Communications Research Laboratory Southeast University State Key Laboratory of Mobile network and Mobile Multimedia Technology Zhongxing Telecommunication Equipment Corporation College of Internet of Things Engineering Hohai University

In this paper, we investigate duplex mode selection and transceiver design for cell-free massive multiple-input multiple-output(MIMO) with network-assisted full duplexing(NAFD), where the remote antenna units(RAUs) simultaneously serve both uplink and downlink users on the same time-frequency resource, and the joint transmission and reception are done at the central processing unit. We consider that each antenna can operate in three modes, i.e., uplink reception, downlink transmission and sleep. In particular, we model the problem as a mixed-integer optimization problem to maximize the aggregated spectral efficiency(SE) of downlinks and uplinks, where the quality-of-service constraints and power budget constraints are considered. Since the uplinks and downlinks are highly coupled, to address the design problem,we resolve the combinatorial problem by a series of nonconvex-convex approximate methods, such as equivalent formulations, iterative success convex approximations, and binary relaxations. In particular, a two-stage strategy is proposed to solve the optimization problem. In the first stage, we fix the mode selection vectors and then obtain the optimal transceivers with such a fairness strategy. In the second stage, with the transceiver parameters obtained from the first stage, we further optimize the duplex mode of each *** algorithms of the two stages will alternately run in several loops until convergence. Numerical results indicate that the proposed solution can obtain SE performance that is close to the optimal exhaustive search solution and yields a higher SE gain compared with the traditional fixed-mode duplex scheme.

关键词： cell-free massive MIMO network-assisted full duplexing mode selection success convex approximations spectral efficiency

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Performance Evaluation of an Anomaly-Detection Algorithm for Keystroke-Typing Based Insider Detection

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Tsinghua Science and Technology 2018年第5期23卷 513-525页

作者： Liang He Zhixiang Li Chao Shen national Key Laboratory of Science and Technology on Blind Signal Processing Chengdu 610041 China Ministry of Education Key Lab for Intelligent networks and network Security Xi'an Jiaotong University Xi'an 710004 China

Keystroke dynamics is the process to identify or authenticate individuals based on their typing rhythm behaviors. Several classifications have been proposed to verify a user＇s legitimacy, and the performances of these classifications should be confirmed to identify the most promising research direction. However, classification research contains several experiments with different conditions such as datasets and methodologies. This study aims to benchmark the algorithms to the same dataset and features to equally measure all performances. Using a dataset that contains the typing rhythm of 51 subjects, we implement and evaluate 15 classifiers measured by Fl-measure, which is the harmonic mean of a false-negative identification rate and false-positive identification rate. We also develop a methodology to process the typing data. By considering a case in which the model will reject the outsider, we tested the algorithms on an open set. Additionally, we tested different parameters in random forest and k nearest neighbors classifications to achieve better results and explore the cause of their high performance. We also tested the dataset on one-class classification and explained the results of the experiment. The top-performing classifier achieves an Fl-measure rate of 92% while using the normalized typing data of 50 subjects to train and the remaining data to test. The results, along with the normalization methodology, constitute a benchmark for comparing the classifiers and measuring the performance of keystroke dynamics for insider detection.

关键词： keystroke dynamics insider identification Fl-measure normalization one-class classification

(3+1)-Dimensional Quantum Mechanics from Monte Carlo Hamiltonian: Harmonic Oscillator

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Communications in Theoretical Physics 2001年第7期36卷 7-10页

作者： LUO Xiang-Qian XU Hao YANG Jie-Chao CHANG Di LIN Yin Helmut Kroger WANG Yu-Li Department of Physics Zhongshan University Guangzhou 510275 China Department de Physique Universite Laval Quebec Quebec GiK 7P4 Canada Department of Physics Zhongshan University Guangzhou 510275 China Guangdong National Communication Network Science & Technology Stock Co. Ltd. Guangzhou 510080 China Guangdong National Communication Network Science & Technology Stock Co. Ltd. Guangzhou 510080 China Guangdong National Communication Network Science & Technology Stock Co. Ltd. Guangzhou 510080 China Department de Physique Universite Laval Quebec Quebec GiK 7P4 Canada Guangdong National Communication Network Science & Technology Stock Co. Ltd. Guangzhou 510080 China

In Lagrangian formulation, it is extremely difficult to compute the excited spectrum and wavefunctions ora quantum theory via Monte Carlo methods. Recently, we developed a Monte Carlo Hamiltonian method for investigating this hard problem and tested the algorithm in quantum-mechanical systems in 1+1 and 2t1 dimensions. In this paper we apply it to the study of thelow-energy quantum physics of the (3+1)-dimensional harmonic oscillator.

关键词： Monte Carlo method, quantum mechanics, computational physics

Some classes of complete permutation polynomials over Fq

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Science China Mathematics 2015年第10期58卷 2081-2094页

作者： WU GaoFei LI Nian HELLESETH Tor ZHANG YuQing State Key Laboratory of Integrated Service networks Xidian University Information Security and national Computing Grid Laboratory Southwest Jiaotong University Department of Informatics University of Bergen national Computer network Intrusion Protection Center University of Chinese Academy of Sciences

By using a powerful criterion for permutation polynomials, we give several classes of complete permutation polynomials over finite fields. First, two classes of complete permutation monomials whose exponents are of Niho type are presented. Second, for any odd prime p, we give a sufficient and necessary condition for a-1xdto be a complete permutation polynomial over Fp4 k, where d =(p4k-1)/(pk-1)+ 1 and a ∈ F*p4k. Finally, we present a class of complete permutation multinomials, which is a generalization of recent work.

关键词： finite field complete permutation polynomials Walsh transform Niho exponents Dickson polynomials

A planar chiral nanostructure with asymmetric transmission of linearly polarized wave and huge optical activity in near-infrared band

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Chinese Physics B 2013年第12期22卷 256-261页

作者：刘道亚罗孝阳刘锦景董建峰 Institute of Optical Fiber Communication and network Technology Ningbo University

Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The designed nanostructure that consists of twisted metallic split-ring resonators on both sides of a dielectric substrate achieves asymmetric transmission for a forward and backward propagating linearly polarized wave by numerical simulation in near-infrared band. Difference in transmission efficiency of the optimized structure between the same polarized waves incident from opposite directions can reach a maximum at the communication wavelength （1.55 μm）. Moreover, the simulation results of this structure also exhibit strong optical activity and circular dichroism.

关键词： asymmetric transmission optical activity linearly polarized wave circular dichroism

Single-molecule devices reveal step-by-step dynamics of hydrogen bonds

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Science China Chemistry 2018年第6期61卷 639-640页

作者： Lifa Ni Dong Xiang Takhee Lee Tianjin Key Laboratory of Optoelectronic Sensor and Sensing network Technology College of Electronic Information and Optical Engineering Nankai University Department of Physics and Astronomy Seoul National University

Intermolecular interactions,including hydrogen bonding,hydrophobic interactions,halogen bonding etc.,are ubiquitous in nature,which play key roles in the basic chemical,physical and biochemical process of *** them,hydrogen bonds are particularly attractive because they dominate many important structures and functions in nature from elegant base-pair interactions in DNAs to sophisticated protein folding and are regarded as an important element in the discovery of new *** better elucidate fundamental mechanisms,

关键词：氢结合单个分子动力学设备相互作用生物化学分子间 DNA