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Optoelectronic Devices and Integration, OEDI 2015

作者： Yi, Lilin Zheng, Ran Li, Weixiong Hu, Weisheng State Key Lab of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Department of Electronic Engineering Shanghai200240 China

ISBN: (纸本)9781943580019

By transferring 100-nm gold coated CVD monolayer graphene onto the well-polished surface of D-shape fiber, we achieved a graphene in-line polarizer with high polarization extinction ratio of 27 dB, low insertion loss of 5 dB@1550nm and strong saturable absorption effect of 14%. To explore the potential applications of the dual-functional device, we demonstrate ultra-short pulse generation using the graphene device. © OSA 2015.

关键词： Graphene

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Early Warning of City-Scale Unusual Social Event on Public Transportation Smartcard Data

Early Warning of City-Scale Unusual Social Event on Public T...

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Symposia and Workshops on Ubiquitous, Autonomic and Trusted Computing, UIC-ATC

作者： Haiyang Wang Xiaming Chen Siwei Qiang Honglun Zhang Yongkun Wang Jianyong Shi Yaohui Jin State Key Lab of Advanced Optical Communication System and Network Shanghai Jiao Tong University P. R. China Network and Information Center Shanghai Jiao Tong University P. R. China School of Naval Architecture Ocean & Civil Engineering Shanghai Jiao Tong University P. R. China

A sudden social crowd event is serious to public safety as it usually triggers huge number of people who are overwhelming to existing public facilities. Detection, early warning of such social crowd events is very important to the city administration but a very challenging problem in research. In this paper, we aim to solve this problem by using the non-sensitive data from public transportation smartcard. We make a detailed analysis of the traffic of people from smartcard data,, we find a 'two-peak' pattern of human flow before, after a social crowd event happening. Motivated by this finding, we propose a framework for early detection of unusual social crowd events by exploiting time series analysis, machine learning technology. We evaluate our model on the real world public transportation data of the biggest metropolitan of China, validate our model with social crowd event data retrieved from the Internet. The evaluation result shows the effectiveness of our model.

关键词： Public transportation Data models History Mobile handsets Urban areas Hidden Markov models

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Discovering Mass Activities Using Anomalies in Individual Mobility Motifs

Discovering Mass Activities Using Anomalies in Individual Mo...

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Symposia and Workshops on Ubiquitous, Autonomic and Trusted Computing, UIC-ATC

作者： Zhenhuan Li Haiyang Wang Xiaming Chen Yongkun Wang Yaohui Jin Wenjun Zhang Inst. of Image Commun. & Inf. Process. Shanghai Jiao Tong University P. R. China State Key Lab of Advanced Optical Communication System and Network Shanghai Jiao Tong University P. R. China Network and Information Center Shanghai Jiao Tong University P. R. China

Mobility motif is a typical topology structure shared by movement trajectories, which could exhibit multi-scale spatio-temporal patterns in human behavior. There are two types of motifs, frequent, infrequent. The infrequent one hasn't got enough attention in research. In this paper, we study the relationship between infrequent motifs, mass activities. We have discovered that crowds are more likely to generate abnormal motifs when they attend activities than on ordinary days. Inspired by the discovery, we propose a novel model to incorporate the connection between motif anomalies, mass activities, which is verified by our real-world data driven analysis. Compared to previous mobility analysis, our work facilitates the inspection of human mobility anomalies in a fresh perspective, it is a promising step towards unraveling the actual causation behind human mobility.

关键词： Buildings Trajectory IEEE 802.11 Standard Data mining Global Positioning System Internet Topology

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Deterministic realization of collective measurements via photonic quantum walks

arXiv

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arXiv 2017年

作者： Hou, Zhibo Tang, Jun-Feng Shang, Jiangwei Zhu, Huangjun Li, Jian Yuan, Yuan Wu, Kang-Da Xiang, Guo-Yong Li, Chuan-Feng Guo, Guang-Can Key Laboratory of Quantum Information University of Science and Technology of China CAS Hefei230026 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei230026 China Naturwissenschaftlich-Technische Fakultät Universität Siegen Siegen57068 Germany Beijing Key Laboratory of Nanophotonics Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing100081 China Institute for Theoretical Physics University of Cologne Cologne50937 Germany Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China Institute of Signal Processing Transmission Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing210003 China

Collective measurements on identically prepared quantum systems can extract more information than local measurements, thereby enhancing information-processing efficiency. Although this nonclassical phenomenon has been known for two decades, it has remained a challenging task to demonstrate the advantage of collective measurements in experiments. Here we introduce a general recipe for performing deterministic collective measurements on two identically prepared qubits based on quantum walks. Using photonic quantum walks, we realize experimentally an optimized collective measurement with fidelity 0.9946 without post selection. As an application, we achieve the highest tomographic efficiency in qubit state tomography to date. Our work offers an effective recipe for beating the precision limit of local measurements in quantum state tomography and metrology. In addition, our study opens an avenue for harvesting the power of collective measurements in quantum information processing and for exploring the intriguing physics behind this power. Copyright © 2017, The Authors. All rights reserved.

关键词： Quantum optics

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Best-fit Cell Attachment for Decoupling DL/UL to Promote Traffic Offloading in HetNets

Best-fit Cell Attachment for Decoupling DL/UL to Promote Tra...

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IEEE International Conference on communications

作者： Hemin Yang Anpeng Huang Linzhen Xie mHealth Lab State Key Lab of Advanced Optical Communication Systems and Networks Peking University

ISBN: (纸本)9781467364300

Heterogeneous networks (HetNets), in which small cells are ultra-densely deployed within a macro cell, is widely regarded as a key solution to mobile traffic offloading. However, this kind of traffic offloading is confronted by two challenges. Firstly, the number of users in any small cell is really limited due to the larger power gap between macros and small cells in HetNets. In return, this phenomenon may degrade traffic offloading performance. Secondly, spectrum efficiency may be deteriorated since uplink channel states are not involved in the conventional cell attachment strategies. To address these challenges, we propose a best-fit cell attachment where downlink and uplink are decoupled and attached to cells independently. Specifically, in this paper, we conceive best-fit strategies for down-link and uplink cell attachment, for taking into account of both channel quality and cell load. And then, their implementation issues in different scenarios are discussed in detail. System-level simulation results demonstrated that our proposal can effectively offload traffic from macros to small cells, and improve data rates for cell-edge users significantly.

关键词： Heterogeneous networks (HetNets) Downlink-Uplink Decouple Traffic Offloading Best-Fit Cell Attachment

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Unrepeatered 515Gb/s Nyquist PDM-128QAM transmission over 120km SSMF with backward Raman amplification

Unrepeatered 515Gb/s Nyquist PDM-128QAM transmission over 12...

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OptoElectronics and communications Conference, OECC

作者： Dan Wang Xin Lv Yixiao Zhu Kaiheng Zou Fan Zhang Lixin Zhu Zhangyuan Chen State Key Lab of Advanced Optical Communication Systems and Networks Peking University Beijing China

We experimentally demonstrate Nyquist superchannel transmission of 515Gb/s (8×64.4Gb/s) PDM-128QAM over single span of 120 km SSMF, using backward Raman amplification at the receiver-side. We achieve a record dis... 详细信息

关键词： optical fiber amplifiers optical transmitters optical fiber communication Stimulated emission optical amplifiers optical receivers optical filters

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Unrepeatered 447Gb/s Nyquist PDM-64QAM transmission over 160km SSMF with Backward Raman Amplification

Unrepeatered 447Gb/s Nyquist PDM-64QAM transmission over 160...

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European Conference on optical communication

作者： Xin Lv Dan Wang Yixiao Zhu Kaiheng Zou Zhennan Zheng Fan Zhang Lixin Zhu Zhangyuan Chen State Key Lab of Advanced Optical Communication Systems and Networks Peking University Beijing China

We experimentally demonstrate Nyquist superchannel transmission of 447 Gb/s (8×55.97Gb/s) PDM-64QAM over single span of 160 km SSMF with backward Raman amplification. We achieve a record distance of unrepeatered ... 详细信息

关键词： Bit error rate optical fibers optical transmitters Power measurement optical filters Stimulated emission Erbium-doped fiber amplifiers

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Analyzing and Modeling Spatio-Temporal Dependence of Cellular Traffic at City Scale

Analyzing and Modeling Spatio-Temporal Dependence of Cellula...

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IEEE International Conference on communications

作者： Xiaming Chen Yaohui Jin Siwei Qiang Weisheng Hu Kaida Jiang State Key Lab of Advanced Optical Communication System and Network Shanghai Jiao Tong University Network and Information Center Shanghai Jiao Tong University

ISBN: (纸本)9781467364300

Traffic characteristics over space and time constitute an important aspect of cellular networks in consideration of resource provision, traffic engineering and system optimization. Despite recent progress in revealing temporal dynamics and spatial inhomogeneity of cellular traffic, limited knowledge about traffic dependence is gained. One of challenges comes from the absence of sustained observations at a network-wide scale. In this paper, we make an analysis on the week-long traffic generated by a large population of users in a city of China, and model traffic dependence along both space and time dimensions. The evaluation results suggest connections between spatio-temporal dependence of cellular traffic and the organization of human lives. Region differences are observed to impact traffic dependence to a great extent. Additionally, interactive knowledge between space and time enhances traffic prediction with a decrease in root-mean-square error of 2.8%～25.2%. We believe that these achievements will benefit multiple research and development areas such as network deploying and simulation researches.

关键词： Spatio-temporal dependence Traffic modeling Mobile measurement Correlation analysis Tide effects

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Intelligent timeout master: Dynamic timeout for SDN-based data centers

Intelligent timeout master: Dynamic timeout for SDN-based da...

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IFIP/IEEE International Symposium on Integrated network Management

作者： Huikang Zhu Hongbo Fan Xuan Luo Yaohui Jin State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Network & Information Center Shanghai Jiao Tong University China

ISBN: (纸本)9781479982424

Software Defined networks (SDN) such as OpenFlow provides better network management for data center by decoupling control plane from data plane. Current OpenFlow controllers install flow rules with a fixed timeout after which the switch automatically removes the rules from its flow table. However, this fixed timeout has shown many disadvantages. For flows with short packet interval, the timeout may be too large so that flow rules stay in the flow table for too long time and result in unnecessary occupation of flow table; for flows with long packet interval or periodic flows, the timeout may be too short, hence producing too many packet-in events and causing overload on the controller. In this paper, we propose the Intelligent Timeout Master, which can assign suitable timeout to different flows according to their characteristics, as well as conduct a feedback control to adjust the max timeout value according to the current flow table occupation, in an effort to avoid flow table overflow. In our experiments, we use real traffic trace and the result confirms that our Intelligent Timeout Master performs quite well in reducing the number of packet-in events as well as flow table occupation.

关键词： Feedback control Switches Telecommunication traffic Algorithm design and analysis Upper bound Heuristic algorithms Monitoring

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Frequency chirp compensation of directly modulated DBR laser

Frequency chirp compensation of directly modulated DBR laser

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International Conference on Transparent optical networks

作者： Zanwei Shen Xuelin Yang Xiaonan Hu Weisheng Hu State Key Lab of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Shanghai P. R. China

ISBN: (纸本)9781467378819

We propose a model to analyze the frequency chirp of directly modulated distributed Bragg reflector (DBR) laser by evaluating the carrier dynamics in DBR. Due to the opposite sign of chirp in the gain and phase sections, the chirp compensation is achieved by injecting simultaneously injecting the data signals into both of the phase and gain sections in DBR laser. The simulation shows that, the overall chirp can be fully compensated, while the residual chirp at the rising and falling edges is only ~2 GHz. Moreover, the corresponding spectrum linewidth is significantly compressed after effective chirp compensation.

关键词： Chirp Distributed Bragg reflectors Refractive index Charge carrier density Frequency modulation Integrated optics Gain

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