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Science Bulletin 2017年第10期62卷 717-723页

作者： Junhui Li Bin Luo Dongyue Yang Longfei Yin Guohua Wu Hong Guo astute Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science and Center for Quantum Information Technology Peking University Beijing 100871 China stute Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing 100876 China School of Electronic Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

When using the image mutual information to assess the quality of reconstructed image in pseudothermal light ghost imaging, a negative exponential behavior with respect to the measurement number is observed. Based on information theory and a few simple and verifiable assumptions, semi-quantitative model of image mutual information under varying measurement numbers is established. It is the Gaussian characteristics of the bucket detector output probability distribution that leads to this negative exponential behavior. Designed experiments verify the model.

关键词： Ghost imaging Image mutual information Information theory Image quality assessment

Blind identification of SFBC-OFDM signals based on the central limit theorem

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arXiv 2018年

作者： Gao, Mingjun Li, Yongzhao Dobre, Octavia A. Al-Dhahir, Naofal State Key Laboratory of Integrated Services Networks Xidian University Xi'an710071 China Department of Electrical and Computer Engineering Memorial University St. John'sNL Canada Electrical and Computer Engineering University of Texas at Dallas RichardsonTX United States

Previous approaches for blind identification of space-frequency block codes (SFBC) do not perform well for short observation periods due to their inefficient utilization of frequency-domain redundancy. This paper proposes a hypothesis test (HT)-based algorithm and a support vector machine (SVM)based algorithm for SFBC signals identification over frequency-selective fading channels to exploit two-dimensional space-frequency domain redundancy. Based on the central limit theorem, space-domain redundancy is exploited to construct the cross-correlation function of the estimator and frequency-domain redundancy is incorporated in the construction of the statistics. The difference between the two proposed algorithms is that the HT-based algorithm constructs a chi-square statistic and employs an HT to make the decision, while the SVM-based algorithm constructs a non-central chi-square statistic with unknown mean as a strongly-distinguishable statistical feature and uses an SVM to make the decision. Both algorithms do not require knowledge of the channel coefficients, modulation type or noise power, and the SVM-based algorithm does not require timing synchronization. Simulation results verify the superior performance of the proposed algorithms for short observation periods with comparable computational complexity to conventional algorithms, as well as their acceptable identification performance in the presence of transmission impairments. Copyright © 2018, The Authors. All rights reserved.

关键词： Support vector machines

Silica capillary based Whispering Gallery Mode resonators and functional fiber devices

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Silica capillary based Whispering Gallery Mode resonators an...

Optical Fiber Communication Conference, OFC 2018

作者： Zhang, Xiaobei Wang, Jiawei Yan, Ming Xiao, Hai Wang, Tingyun Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai University Shanghai200444 China Department of Electrical and Computer Engineering Clemson University Clemson29634 United States

A novel and compact silica capillary based Whispering Gallery Mode resonators and functional fiber devices are demonstrated with Fano resonances observed, while the temperature, refractive index and strain sensing are... 详细信息

ISBN: (纸本)9781943580385

关键词： Silica

Full-space Cloud of Random Points with a Scrambling Metasurface

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Light(Science & Applications) 2018年第1期7卷 467-474页

作者： Zile Li Qi Dai Muhammad Q.Mehmood Guangwei Hu Boris Luk’yanchuk Jin Tao Chenglong Hao Inki Kim Heonyeong Jeong Guoxing Zheng Shaohua Yu Andrea Alù Junsuk Rho Cheng-Wei Qiu School of Electronic Information Wuhan UniversityWuhan 430072China NOEIC State Key Laboratory of Optical Communication Technologies and NetworksWuhan Research Institute of Posts and TelecommunicationsWuhan 430074China Department of Electrical Engineering Information Technology University of the PunjabFerozpur Road54000 LahorePakistan Department of Electrical and Computer Engineering National University of Singapore4 Engineering Drive 3Singapore 117583Singapore Advanced Science Research Center City University of New YorkNew York 10031USA Data Storage Institute A*STAR(Agency for ScienceTechnology and Research)2 Fusionopolis Way#08-01Innovis 138634Singapore Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea National Institute of Nanomaterials Technology(NINT) Pohang 37673Republic of Korea

With the rapid progress in computer science,including artificial intelligence,big data and cloud computing,full-space spot generation can be pivotal to many practical applications,such as facial recognition,motion detection,augmented reality,*** opportunities may be achieved by using diffractive optical elements(DOEs)or light detection and ranging(LIDAR).However,DOEs suffer from intrinsic limitations,such as demanding depth-controlled fabrication techniques,large thicknesses(more than the wavelength),Lambertian operation only in half space,*** nevertheless relies on complex and bulky scanning systems,which hinders the miniaturization of the spot ***,inspired by a Lambertian scatterer,we report a Hermitian-conjugate metasurface scrambling the incident light to a cloud of random points in full space with compressed information density,functioning in both transmission and reflection *** 4044 random spots are experimentally observed in the entire space,covering angles at nearly 90°.Our scrambling metasurface is made of amorphous silicon with a uniform subwavelength height,a nearly continuous phase coverage,a lightweight,flexible design,and low-heat ***,it may be mass produced by and integrated into existing semiconductor foundry *** work opens important directions for emerging 3D recognition sensors,such as motion sensing,facial recognition,and other applications.

关键词： conjugate directions amorphous

High contrast linking 6 lasers to a 1 GHz Ybfiber laser frequency comb

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arXiv 2018年

作者： Ma, Yuxuan Meng, Fei Wang, Yan Wang, Aimin Zhang, Zhigang State Key Laboratory of Advanced Optical Communication System and Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China National Institute of Metrology Beijing100029 China

We demonstrate a 0.95 GHz repetition rate fully stabilized Yb:fiber frequency comb without optical amplification. Benefitted from the high mode power and high coherence, this comb achieved 35 dB to 42 dB signal to noise ratio on the direct heterodyne beat signals with at least 6 continuous wave lasers (at 580nm, 679nm, 698nm, 707nm, 813nm and 922 nm) while keeping >40 dB carrier envelop frequency signal. It can be used for the direct measurement of optical frequencies in visible and near-infrared wavelengths, and has a great potential on simultaneous comparison of multiple optical frequencies. Copyright © 2018, The Authors. All rights reserved.

关键词： Optical materials

A simple channel independent beamforming scheme with circular array

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arXiv 2018年

作者： Jing, Haiyue Cheng, Wenchi Xia, Xiang-Gen State Key Laboratory of Integrated Services Networks Xidian University Xi'an710071 China Xidian University and the Department of Electrical and Computer Engineering University of Delaware NewarkDE19716 United States

In this letter, we consider a uniform circular array (UCA) based line-of-sight (LOS) multiple-input-multiple-output (MIMO) system, where the transmit and receive UCAs are aligned with each other. We propose a simple channel independent beamforming scheme with fast symbol-wise maximum likelihood (ML) detection. Copyright © 2018, The Authors. All rights reserved.

关键词： Beamforming

An ultra-compact MMI-based wavelength diplexer employing subwavelength grating 14

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An ultra-compact MMI-based wavelength diplexer employing sub...

14th International Conference on Group IV Photonics, GFP 2017

作者： Liu, Lu Deng, Qingzhong Zhou, Zhiping State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China

Through the refractive index engineering of the subwavelength grating, an ultra-compact multimode interference based diplexer is proposed and demonstrated. It is 43.4 μm in length, only ~30% of its conventional count... 详细信息

ISBN: (纸本)9781509065684

关键词： Silicon photonics

Refractive index engineering of high performance coupler for compact photonic integrated circuits

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Refractive index engineering of high performance coupler for...

作者： Liu, Lu Zhou, Zhiping State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China

High performance couplers are highly desired in many applications, but the design is limited by nearly unchangeable material refractive index. To tackle this issue, refractive index engineering method is investigated, which can be realized by subwavelength grating. Subwavelength gratings are periodical structures with pitches small enough to locally synthesize the refractive index of photonic waveguides, which allows direct control of optical profile as well as easier fabrication process. This review provides an introduction to the basics of subwavelength structures and pay special attention to the design strategies of some representative examples of subwavelength grating devices, including: edge couplers, fiber-chip grating couplers, directional couplers and multimode interference couplers. Benefited from the subwavelength grating which can engineer the refractive index as well as birefringence and dispersion, these devices show better performance when compared to their conventional counterparts. © 2017 The Japan Society of Applied Physics.

关键词： Refractive index

Flexible energy management protocol for cooperative EV-to-EV charging

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arXiv 2018年

作者： Zhang, Rongqing Cheng, Xiang Yang, Liuqing State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing China Department of Electrical and Computer Engineering Colorado State University CO United States Shenzhen Research Institute of Big Data Shenzhen Guangdong China

In this paper, we investigate flexible power transfer among electric vehicles (EVs) from a cooperative perspective in an EV system. First, the concept of cooperative EV-to- EV (V2V) charging is introduced, which enables active cooperation via charging/discharging operations between EVs as energy consumers and EVs as energy providers. Then, based on the cooperative V2V charging concept, a flexible energy management protocol with different V2V matching algorithms is proposed, which can help the EVs achieve more flexible and smarter charging/discharging behaviors. In the proposed energy management protocol, we define the utilities of the EVs based on the cost and profit through cooperative V2V charging and employ the bipartite graph to model the charging/discharging cooperation between EVs as energy consumers and EVs as energy providers. Based on the constructed bipartite graph, a max-weight V2V matching algorithm is proposed in order to optimize the network social welfare. Moreover, taking individual rationality into consideration, we further introduce the stable matching concepts and propose two stable V2V matching algorithms, which can yield the EV-consumer-optimal and EVprovider- optimal stable V2V matchings, respectively. Simulation results verify the efficiency of our proposed cooperative V2V charging based energy management protocol in improving the EV utilities and the network social welfare as well as reducing the energy consumption of the EVs. Copyright © 2018, The Authors. All rights reserved.

关键词： Electric vehicles

Towards a stochastic model for integrated detection and filtering of DoS attacks in cloud environments 17

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Towards a stochastic model for integrated detection and filt...

2nd International Conference on Big Data Cloud and Applications, BDCA 2017

作者： El Mir, Iman Kim, Dong Seong Haqiq, Abdelkrim Computer Networks Mobility and Modeling Laboratory Faculty of Sciences and Technology Hassan 1st Univ Morocco Department of Computer Science and Software Engineering University of Canterbury New Zealand

ISBN: (纸本)9781450348522

Cloud Data Center (CDC) security remains a major challenge for business organizations and takes an important concern with research works. The attacker purpose is to guarantee the service unavailability and maximize the financial loss costs. As a result, Distributed Denial of Service (DDoS) attacks have appeared as the most popular attack. The main aim of such attacks is to saturate and overload the system network through a massive data packets size flooding toward a victim server and to block the service to users. This paper provides a defending system in order to mitigate the Denial of Service (DoS) attack in CDC environment. Basically it outlines the different techniques of DoS attacks and its countermeasures by combining the filtering and detection mechanisms. We presented an analytical model based on queueing model to evaluate the impact of flooding attack on cloud environment regarding service availability and QoS performance. Consequently, we have plotted the response time, throughput, drop rate and resource computing utilization varying the attack arrival rate. We have used JMT (Java Modeling Tool) simulator to validate the analytical model. Our approach was appeared powerful for attacks mitigation in the cloud environment. © 2017 ACM.

关键词： Queueing theory