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High sensitivity dual microring sensor based on intensity detection

High sensitivity dual microring sensor based on intensity de...

Asia Communications and Photonics Conference and Exhibition(2010亚洲光纤通信与光弹博览会及研讨会 ACP 2010)

作者： H.Yi D.S.Citrin Z.Zhou State Key Laboratory on Advanced Optical Communication Systems and Networks Peking University Beij School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta 30318 USA State Key Laboratory on Advanced Optical Communication Systems and Networks Peking University Beij

By employing the enhanced phase transfer of single microring resonator, the enhanced intensity sensing is obtained based on the dual microring resonator with coupled mode theory.

ISBN: (纸本)9780819485588

By employing the enhanced phase transfer of single microring resonator, the enhanced intensity sensing is obtained based on the dual microring resonator with coupled mode theory.

关键词： Coupled mode theory Coupled resonators Light wavelength Optical resonators Resonance Transmission coefficient

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User-level virtual networking mechanisms to support virtual machine migration over multiple clouds

User-level virtual networking mechanisms to support virtual ...

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IEEE Globecom Workshops

作者： Maurício Tsugawa Pierre Riteau Andréa Matsunaga José Fortes Advanced Computing and Information Systems Laboratory Department of Electrical and Computer Engineering University of Florida Gainesville FL USA IRISA Laboratory Université de Rennes 1 Rennes France

Dynamic allocation of multiple cloud resources adapting to application needs over time can be achieved by taking advantage of wide-area VM live migration technologies. However, migration of VMs across different subnets, potentially in multiple clouds, requires networking support to keep the network state of moving VMs unchanged. Two problems make traditional solutions to machine mobility inefficient in this scenario: (1) administrative overheads due to coordination requirements between moving machines and the network infrastructure; and (2) degraded network performance of machines moved away from their “home” networks. New solutions are needed to efficiently support the migration of virtual machines over multiple cloud providers. The user-level virtual network architecture presented in this paper implements mechanisms to allow VM migration over clouds without requiring support from the physical network infrastructure, and automatically reconfiguring virtual networks to maximize the network performance of migrated virtual machines.

关键词： IP networks Virtual machining Routing Cloud computing Virtual machine monitors Software

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Power Control for Radio-Over-Fiber Downlinks in Frequency Division Multiplexing Cellular Communication systems

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IEEE/OSA Journal of Optical Communications and Networking 2010年第12期2卷 1022-1030页

作者： Yinqing Pei Xiupu Zhang Kun Xu Xiaoqiang Sun Bouchaib Hraimel Jian Wu Jintong Lin Advanced Photonic Systems Laboratory Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing China Beijing University of Posts and Telecommunications

This paper, for the first time to our knowledge, introduces a power control technique for radio-over-fiber (RoF) downlinks in frequency division multiplexing (FDM) cellular communication systems. The power control technique, which has been widely used in traditional wireless systems, is to radiate sufficient power to establish an adequate service for a particular distance. Due to RoF link nonlinearities, RoF systems can be limited by nonlinear distortion that is dependent on the input RF power. The power control technique can manage the input power of RF signals to the RoF links, and thus nonlinear distortion and interchannel interference can be diminished. In this paper, we theoretically analyze the necessity of power control in FDM-RoF systems and then propose a simple power control algorithm. Finally, the proposed power control algorithm is verified in four- and nine-channel orthogonal frequency division multiplexing ultrawideband (OFDM UWB) wireless systems with RoF distribution.

关键词： Power control Radio frequency Wireless communication Nonlinear distortion OFDM Frequency division multiplexing Downlink

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Passive-scheme analysis for solving the untrusted source problem in quantum key distribution

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Physical Review A 2010年第4期81卷 042320-042320页

作者： Xiang Peng Bingjie Xu Hong Guo []CREAM Group State Key Laboratory of Advanced Optical Communication Systems and Networks (Peking University) and Institute of Quantum Electronics School of Electronics Engineering and Computer Science Peking University Beijing 100871 People's Republic of China

As a practical method, the passive scheme is useful to monitor the photon statistics of an untrusted source in a “Plug & Play” quantum key distribution (QKD) system. In a passive scheme, three kinds of monitor mode can be adopted: average photon number (APN) monitor, photon number analyzer (PNA), and photon number distribution (PND) monitor. In this paper, the security analysis is rigorously given for the APN monitor, while for the PNA, the analysis, including statistical fluctuation and random noise, is addressed with a confidence level. The results show that the PNA can achieve better performance than the APN monitor and can asymptotically approach the theoretical limit of the PND monitor. Also, the passive scheme with the PNA works efficiently when the signal-to-noise ratio (RSN) is not too low and so is highly applicable to solve the untrusted source problem in the QKD system.

关键词： Signal to noise ratio

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Passive scheme with a photon-number-resolving detector for monitoring the untrusted source in a plug-and-play quantum-key-distribution system

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Physical Review A 2010年第4期82卷 042301-042301页

作者： Bingjie Xu Xiang Peng Hong Guo []CREAM Group State Key Laboratory of Advanced Optical Communication Systems and Networks （Peking University） and Institute of Quantum Electronics School of Electronics Engineering and Computer Science Peking University Beijing 100871 People’s Republic of China

A passive scheme with a beam splitter and a photon-number-resolving (PNR) detector is proposed to verify the photon statistics of an untrusted source in a plug-and-play quantum-key-distribution system by applying a three-intensity decoy-state protocol. The practical issues due to statistical fluctuation and detection noise are analyzed. The simulation results show that the scheme can work efficiently when the total number of optical pulses sent from Alice to Bob is above 108, and the dark count rate of the PNR detector is below 0.5 counts/pulse, which is realizable with current techniques. Furthermore, we propose a practical realization of the PNR detector with a variable optical attenuator combined with a threshold detector.

关键词： Photons

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True random number generator based on the phase noise of laser

True random number generator based on the phase noise of las...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Yu Liu Wenzhuo Tang Hong Guo State Key Laboratory of Advanced Optical Communication Systems and Networks and Institute of Quantum Electronics School of Electronics Engineering and Computer Science Peking University Beijing China

We present a true random number generator with the high generation rate of 80 Mbit/s, based on the measurement of the phase noise of a single mode vertical cavity surface emitting laser (VCSEL).

ISBN: (纸本)9781557528896

We present a true random number generator with the high generation rate of 80 Mbit/s, based on the measurement of the phase noise of a single mode vertical cavity surface emitting laser (VCSEL).

关键词： Random number generation Phase noise Laser noise Vertical cavity surface emitting lasers Surface emitting lasers Laser theory Laser modes Fluctuations Delay effects Noise measurement

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A Hierarchical Image Annotation Method Based on SVM and Semi-supervised EM

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自动化学报 2010年第7期36卷 960-967页

作者： GAO Yan-Yu YIN Yi-Xin UOZUMI Takashi School of Information Engineering University of Science and Technology Beijing Beijing 100083 P.R.China Key Laboratory of Advanced Control of Iron and Steel Process (Ministry of Education) University of Science and Technology Beijing Beijing 100083 P. R. China Department of Computer Science and Systems Engineering Muroran Institute of Technology Muroran 050- 8585 Japan

Automatic image annotation, which aims at automatically identifying and then assigning semantic keywords to the meaningful objects in a digital image, is not a very difficult task for human but has been regarded as a difficult and challenging problem to machines. In this paper, we present a hierarchical annotation scheme considering that generally human s visual identification to a scenery object is a rough-to-fine hierarchical process. First, the input image is segmented into multiple regions and each segmented region is roughly labeled with a general keyword using the multi-classification support vector machine. Since the results of rough annotation affect fine annotation directly, we construct the statistical contextual relationship to revise the improper labels and improve the accuracy of rough annotation. To obtain reasonable fine annotation for those roughly classified regions, we propose an active semi-supervised expectation-maximization algorithm, which can not only find the representative pattern of each fine class but also classify the roughly labeled regions into corresponded fine classes. Finally, the contextual relationship is applied again to revise the improper fine labels. To illustrate the effectiveness of the presented approaches, a prototype image annotation system is developed, the preliminary results of which showed that the hierarchical annotation scheme is effective.

关键词：数字图像自动化系统准确性意义图像标注

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The Optimal Network Version of Water-filling: Polite Water-filling

The Optimal Network Version of Water-filling: Polite Water-f...

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中国电子学会第十七届信息论学术年会

作者： Liu An Liu Youjian Xiang Haige Luo Wu State Key Laboratory of Advanced Optical Communication Systems & Networks School of EECSPeking Univ Department of Electrical Computerand Energy EngineeringUniversity of Colorado at BoulderUSA

We found the long-sought optimal water-filling for networks, representing a major advance for the optimization of general MIMO interference networks under the assumption of Gaussian input,which has been an open problem due to its *** key to this open problem is to find the optimal input structure,just like the cases of single-user MIMO channels and sum-rate maximization of MIMO multiaccess channels where the complexity of the optimization is greatly reduced by exploiting the water-filling *** general cases,the problem has been open for a long *** found the optimal input structure called polite water-filling, satisfied by all Pareto optimal input This network version of water-filling is polite because it optimally balances between reducing interference to others and maximizing a link's own *** can be immediately used to design/improve almost allnetwork optimization *** applications,including the weighted sum-rate maximization,are discussed to demonstrate the impact of the result.

关键词： Water-filling MIMO Network Transmitter Optimization Network Information Theory

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Improving the performance of hypervisor-based fault tolerance

Improving the performance of hypervisor-based fault toleranc...

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International Symposium on Parallel and Distributed Processing (IPDPS)

作者： Jun Zhu Wei Dong Zhefu Jiang Xiaogang Shi Zhen Xiao Xiaoming Li School of Electronics Engineering & Computer Sciences Peking University Beijing China State Key Laboratory of Advanced Optical Communication Systems & Networks Peking University Beijing China

ISBN: (纸本)9781424464425

Hypervisor-based fault tolerance (HBFT), a checkpoint-recovery mechanism, is an emerging approach to sustaining mission-critical applications. Based on virtualization technology, HBFT provides an economic and transparent solution. However, the advantages currently come at the cost of substantial overhead during failure-free, especially for memory intensive applications. This paper presents an in-depth examination of HBFT and options to improve its performance. Based on the behavior of memory accesses among checkpointing epochs, we introduce two optimizations, read fault reduction and write fault prediction, for the memory tracking mechanism. These two optimizations improve the mechanism by 31.1% and 21.4% respectively for some application. Then, we present software-superpage which efficiently maps large memory regions between virtual machines (VM). By the above optimizations, HBFT is improved by a factor of 1.4 to 2.2 and it achieves a performance which is about 60% of that of the native VM.

关键词： Fault tolerance Virtual manufacturing Virtual machine monitors Application software Fault tolerant systems Mission critical systems Read-write memory Checkpointing Virtual machining Maintenance

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Iterative Polite Water-Filling for Weighted Sum-Rate Maximization in iTree Networks

Iterative Polite Water-Filling for Weighted Sum-Rate Maximiz...

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2010 IEEE Global Telecommunications Conference GLOBECOM 2010

作者： An Liu Youjian Liu Haige Xiang Wu Luo State Key Laboratory of Advanced Optical Communication Systems & Networks School of EECS Peking University China Department of Electrical and Computer Engineering University of Colorado Boulder USA

It is well known that in general, the traditional water-filling is far from optimal in networks. We recently found the long-sought network version of water-filling named polite water-filling that is optimal for a large class of MIMO networks called B-MAC networks, of which interference Tree (iTree) networks is a subset whose interference graphs have no directional loop. iTree networks is a natural extension of both broadcast channel (BC) and multiaccess channel (MAC) and possesses many desirable properties for further information theoretic study. Given the optimality of the polite water-filling, general purpose optimization algorithms for networks are no longer needed because they do not exploit the structure of the problems. Here, we demonstrate it through the weighted sum-rate maximization. The significance of the results is that the algorithm can be easily modified for general B-MAC networks with interference loops. It illustrates the properties of iTree networks and for the special cases of MAC and BC, replaces the current steepest ascent algorithms for finding the capacity regions. The fast convergence and high accuracy of the proposed algorithms are verified by simulation.

关键词： Covariance matrix MIMO Convergence Interference cancellation Optimization Algorithm design and analysis

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