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Realization of population inversion between 7S_(1/2) and 6P_(3/2) levels of cesium for four-level active optical clock

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Science China(Physics,Mechanics & Astronomy) 2013年第6期56卷 1107-1110页

作者： WANG YanFei WANG DongYing ZHANG TongGang HONG YeLong ZHANG ShengNan TAO ZhiMing XIE XiaoPeng CHEN JingBiao State Key Laboratory of Advanced Optical Communication Systems and Networks Institute of Quantum ElectronicsSchool of Electronics Engineering & Computer SciencePeking University

We demonstrate experimentally the population inversion between 7S1/2 and 6P3/2 levels of cesium in thermal cesium cell with a 455.5 nm pumping *** calculate the relative population probabilities at each level theoretically with the density matrix *** a steady state,5.8% atoms are at 7S1/2 level and 2.9% at 6P3/2 level,which builds up the population inversion between the two *** obtain the fluorescence spectra produced in thermal cesium cell in our *** measured relative intensity of each available fluorescence spectral line in the experiment agrees very well with the theoretical *** demonstrated population inversion between 7S1/2 and 6P3/2 levels can be used to construct an active optical clock of four-level system with a wavelength of 1469.9 nm.

关键词： active optical clock four-level system population inversion

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Integration of split ring resonators (SRRs) to UHF RFID tag antenna for size reduction

Integration of split ring resonators (SRRs) to UHF RFID tag ...

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International Conference on engineering Technology and Technopreneuship (ICE2T)

作者： Nor Hidayah Daud Alyani Ismail Adam Reda Hasan Alhawari Aduwati Sali Mohd Fadlee A. Rasid Ali Sadeq Abdulhadi Jalal Department of Computer and Communication SYstems Engineering Wireless and Photonic Networks Research Centre Halal Products Research Institute Universiti Putra Malaysia Serdang Selangor Malaysia Universiti Putra Malaysia Serdang Selangor MY

This paper presents the design of miniaturized dipole antenna for passive Radio Frequency Identification (RFID). The proposed tag antenna is designed in such away that covers the Malaysian Ultra High-Frequency (UHF) RFID frequency band. The proposed tag antenna was designed using a double-sided Flame Retardant 4 (FR-4) substrate. The antenna's configuration consists of meander dipole antenna incorporated with metamaterial square split-ring resonators (SRRs) and capacitive tip-loading. This antenna designed focusing on the antenna parameters such as size, gain, radiation pattern, matching impedance and read range. In this work, the results show that the SRR structure is capable to reduce the size of the tag design by increasing the length of the unit cell.

关键词： Dipole antennas Radiofrequency identification Resonant frequency UHF antennas Loading

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Active optical clock based on four-level quantum system

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Chinese Science Bulletin 2013年第18期58卷 2033-2038页

作者： ZHANG TongGang WANG YanFei ZANG XiaoRun ZHUANG Wei CHEN JingBiao State Key Laboratory of Advanced Optical Communication Systems and Networks Institute of Quantum ElectronicsSchool of Electronics Engineering & Computer SciencePeking University

Active optical clock,a new conception of atomic clock,has been proposed *** this work,we propose a scheme of active optical clock based on four-level quantum *** final accuracy and stability of two-level quantum system are limited by second-order Doppler shift of thermal atomic *** three-level quantum system,they are mainly limited by light shift of pumping laser *** limitations can be avoided effectively by applying the scheme proposed *** atom four-level quantum system,as a typical example,is *** population inversion between 6S 1/2 and 5P 3/2 states can be built up at a time scale of 10-6 *** the mechanism of active optical clock,in which the cavity mode linewidth is much wider than that of the laser gain profile,it can output a laser with quantum-limited linewidth narrower than 1 Hz in *** experimental configuration is designed to realize this active optical clock.

关键词：主动光学量子系统四能级时钟三能级系统激光增益多普勒频移粒子数反转

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EURETILE Design Flow: Dynamic and Fault Tolerant Mapping of Multiple Applications Onto Many-Tile Systems

EURETILE Design Flow: Dynamic and Fault Tolerant Mapping of ...

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International Symposium on Parallel and Distributed Processing with Applications, ISPA

作者： Lars Schor Iuliana Bacivarov Luis Gabriel Murillo Pier Stanislao Paolucci Frédéric Rousseau Ashraf El Antably Robert Buecs Nicolas Fournel Rainer Leupers Devendra Rai Lothar Thiele Laura Tosoratto Piero Vicini Jan Weinstock Computer Engineering and Networks Laboratory Zurich Switzerland Institute for Communication Technologies and Embedded Systems (ICE) RWTH Aachen University Germany INFN Roma “La Sapienza” Roma Italy System Level Synthesis Group TIMA Laboratory (CNRS/UIF/INPG) Grenoble France

EURETILE investigates foundational innovations in the design of massively parallel tiled computing systems by introducing a novel parallel programming paradigm and a multi-tile hardware architecture. Each tile includes multiple general-purpose processors, specialized accelerators, and a fault-tolerant distributed network processor, which connects the tile to the inter-tile communication network. This paper focuses on the EURETILE software design flow, which provides a novel programming environment to map multiple dynamic applications onto a many-tile architecture. The elaborated high-level programming model specifies each application as a network of autonomous processes, enabling the automatic generation and optimization of the architecture-specific implementation. Behavioral and architectural dynamism is handled by a hierarchically organized runtime-manager running on top of a lightweight operating system. To evaluate, debug, and profile the generated binaries, a scalable many-tile simulator has been developed. High system dependability is achieved by combining hardware-based fault awareness strategies with software-based fault reactivity strategies. We demonstrate the capability of the design flow to exploit the parallelism of many-tile architectures with various embedded and high performance computing benchmarks targeting the virtual EURETILE platform with up to 192 tiles.

关键词： computer architecture Program processors Hardware Programming Optimization Abstracts

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Secure Deduplication Storage Systems with Keyword Search

Secure Deduplication Storage Systems with Keyword Search

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IEEE International Conference on Advanced Information Networking and Applications

作者： Jin Li Xiaofeng Chen Fatos Xhafa Leonard Barolli School of Computer Science Guangzhou University China State Key Laboratory of Integrated Service Networks (ISN) Xidian University P.R. China Department of Languages and Informatics Systems Technical University of Catalonia Barcelona Spain Department of Information and Communication Engineering Fukuoka Institute of Technology Japan

ISBN: (纸本)9781479936311

Data deduplication is an attractive technology to reduce storage space and upload bandwidth for increasing vast amount of duplicated and redundant data. In a cloud storage system with data deduplication, duplicate copies of data will be eliminated and only one copy will be kept in the storage. To protect the confidentiality of sensitive data while supporting deduplication, the convergent encryption technique has been proposed to encrypt the data before outsourcing. However, the issue of keyword search over encrypted data in deduplication storage system has to be addressed for efficient data utilization. This paper firstly proposes two constructions which support secure keyword search in this scenario. In these constructions, the integrity of the data can be realized by just checking the convergent key, without other traditional integrity auditing mechanisms. Security analysis demonstrates that our keyword search schemes are secure in terms of the definitions specified in the proposed security model.

关键词： Deduplication distributed storage system reliability secret sharing

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Opportunistic Full-Duplex Relay Selection for Decode-and-Forward Cooperative networks over Rayleigh Fading Channels

Opportunistic Full-Duplex Relay Selection for Decode-and-For...

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IEEE International Conference on communications

作者： Bin Zhong Dandan Zhang Zhongshan Zhang Zhengang Pan Keping Long Athanasios V. Vasilakos Technology Research Center for Convergence Networks and Ubiquitous Services University of Science and Technology Beijing (USTB) Beijing China National Mobile Communications Research Laboratory Southeast University Green Communication Research Center (GCRC) of China Mobile Research Institute (CMRI) Department of Computer and Telecommunications Engineering University of Western Macedonia

The performance analysis of optimal relay decode-and-forward (DF) selection for both the full-duplex (FD) and half-duplex (HD) relaying modes is studied, with some important factors such as the distributions of the received signal-to-noise ratio (SNR), the outage probability and the average channel capacity, etc., being taken into account. Different from the conventional relay selection schemes, the trade-off between the FD and HD modes is studied, with the former suffering from the impact of residual self-interference while the latter consuming more channel resources than the former by allocating two orthogonal channels for transmission and reception. The optimal power allocation (OPA) subject to individual power constrains (IPC) and sum power constrains (SPC) are also analyzed in the proposed FD scheme. In particular, the exact closed-form expressions for outage probability of the proposed FD relay selection scheme over independent and identically distributed (i.i.d.) Rayleigh fading channels are derived in this paper, with the validity of the proposed analysis being proven by simulation. It is also shown that the proposed FD scheme outperforms the HD mode in terms of average channel capacity by about 33.1%, provided that the self-interference can be successfully suppressed below the noise power level.

关键词： Relays High definition video Analytical models Signal to noise ratio Resource management Cooperative systems Wireless communication

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Carrier-grade internet access sharing in wireless mesh networks: The vision of the CARMNET project 9

Carrier-grade internet access sharing in wireless mesh netwo...

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9th Advanced International Conference on Telecommunications, AICT 2013

作者： Glabowski, Mariusz Szwabe, Andrzej Department of Communication and Computer Networks Poznan University of Technology Poznan Poland Institute of Control and Information Engineering Poznan University of Technology Poznan Poland

ISBN: (纸本)9781612082790

The paper presents the vision of CARMNET - a Swiss-Polish project aimed at investigating "CARrier-grade delay-aware resource management for wireless multihop/ Mesh networks". The project focuses on developing solutions that will motivate telecom operators to reconsider their view on user-operated IEEE 802.11-compliant wireless mesh networks. The project is driven by the vision of networks operated jointly by telecom operators - likely appreciating the CARMNET compliance with their IP Multimedia Subsystem (IMS) infrastructure - and a community of users contributing to and enjoying the pervasiveness of the CARMNET-based Internet access. The project aims at providing, both telecom operators and potential end users, with solutions that will create appropriately strong incentives - technological, functional and economical - for a widespread adoption of CARMNET-like networks within a steadily expanding group of users. Initial results indicate, that despite the originality of the project vision, the preliminary CARMNET system architecture complies with key relevant standards. Copyright © 2013 IARIA.

关键词： MESH networking

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How shadowing hurts vehicular communications and how dynamic beaconing can help

How shadowing hurts vehicular communications and how dynamic...

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32nd IEEE Conference on computer communications, IEEE INFOCOM 2013

作者： Sommer, Christoph Joerer, Stefan Segata, Michele Tonguz, Ozan Cigno, Renato Lo Dressler, Falko Computer and Communication Systems Institute of Computer Science University of Innsbruck Austria Electrical and Computer Engineering Dept. Carnegie Mellon University Pittsburgh PA United States Systems and Networks Dept. of Information Engineering and Computer Science University of Trento Italy

ISBN: (纸本)9781467359467

We study the effect of radio signal shadowing dynamics, caused by vehicles and by buildings, on the performance of beaconing protocols in Inter-Vehicular communication (IVC). Recent research indicates that beaconing, i.e., one hop message broadcast, shows excellent characteristics and can outperform other communication approaches for both safety and efficiency applications, which require low latency and wide area information dissemination, respectively. We show how shadowing dynamics of moving obstacles hurt IVC, reducing the performance of beaconing protocols. At the same time, shadowing also limits the risk of overloading the wireless channel. To the best of our knowledge, this is the first study identifying the problems and resulting possibilities of such dynamic radio shadowing. We demonstrate how these challenges and opportunities can be taken into account and outline a novel approach to dynamic beaconing. It provides low-latency communication (i.e., very short beaconing intervals), while ensuring not to overload the wireless channel. The presented simulation results substantiate our theoretical considerations. © 2013 IEEE.

关键词： Information dissemination

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Geometric phase gate for entangling two Bose-Einstein condensates

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Physical Review A 2014年第5期89卷 053607-053607页

作者： Mahmood Irtiza Hussain Ebubechukwu O. Ilo-Okeke Tim Byrnes State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing 100871 People's Republic of China Centre for Quantum Dynamics Griffith University Nathan Queensland 4111 Australia Department of Physics Federal University of Technology P. M. B. 1526 Owerri Imo State Nigeria National Institute of Informatics 2-1-2 Hitotsubashi Chiyoda-Ku Tokyo 101-8430 Japan

We propose a method of entangling two spinor Bose-Einstein condensates using a geometric phase gate. The scheme relies upon only the ac Stark shift and a common controllable optical mode coupled to the spins. Our scheme allows for the creation of an SzSz-type interaction where Sz is the total spin. The geometric phase gate can be executed in times of the order of 2πℏ/G, where G is the magnitude of the Stark shift. In contrast to related schemes which relied on a fourth-order interaction to produce entanglement, this is a second-order interaction in the number of atomic transitions. Closed expressions for the entangling phase are derived and the effects of decoherence due to cavity decay, spontaneous emission, and incomplete de-entangling of the light to the Bose-Einstein condensates are analyzed.

关键词： BOSE-Einstein condensation GEOMETRIC quantum phases QUANTUM entanglement STARK effect SPIN-spin interactions

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The Design and Implementation of a DTN Naming System

The Design and Implementation of a DTN Naming System

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3rd International Conference on Computational Science, engineering and Information Technology, CCSEIT 2013

作者： Chen, Lishui Wang, Songyang Sun, Zhenxi Yan, Changjiang Rao, Huijuan Science and Technology on Information Transmission and Dissemination in Communication Networks Lab. Shijiazhuang 050081 China School of Computer Science and Engineering Beihang University Beijing 100191 China Department of Communication Engineering Harbin Institute of Technology Harbin 150001 China

ISBN: (纸本)9783319009506

This paper presents the design and implementation of the naming mechanism (NAME), a resource discovery and service location approach for Delay/Disruption-Tolerant Network (DTN). First discuss the architecture of NAME mainly including Name Knowledge Base, Name Dissemination, Name Resolution and Name-based Routing. In the design and implementation of NAME, we introduce the simple name-specifiers to describe name, the name-tree for name storage and the efficient predicate-based routing algorithm. Future work is finally discussed for completing NAME and providing APIs for abundant applications.

关键词： Knowledge based systems

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