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2011 30th URSI General Assembly and Scientific Symposium, URSIGASS 2011

作者： Luo, Bin Guo, Hong State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing 100871 China

ISBN: (纸本)9781424451173

Dispersion properties of an optical medium can be greatly changed using electromagnetically induced transparency (EIT) and other nonlinear effects. Thus, the group velocity of light pulse can be much smaller (greater or even negative) than light speed in vacuum, which is called slow (fast) light. Slow and fast light are very useful in optical processing, such as optical buffer, switching, and storage devices. Usually, slow and fast light cannot be generated simultaneously in the same medium. In this paper, we propose applicable level structures to generate controllable slow and fast light simultaneously at two frequencies, with the same polarization. © 2011 IEEE.

关键词： Light

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Simulative performance evaluation of the simTD Self Organizing Traffic Information System

Simulative performance evaluation of the simTD Self Organizi...

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IFIP Annual Mediterranean Ad Hoc Networking Workshop

作者： Eckhoff, David Gansen, Tobias Manz, Robert Thum, Daniela Klages, Oliver Sommer, Christoph Computer Networks and Communication Systems Dept. of Computer Science University of Erlangen Germany AUDI AG/Audi Electronics Venture GmbH Germany C4c Engineering GmbH Germany

ISBN: (纸本)9781457709005

The simTD (Safe and Intelligent Mobility: Test Field Germany) research project is another step towards bringing Car-to-X technology to marketability. One of its envisioned applications is a Traffic Information System (TIS) based on self-generated maps for vehicles not equipped with digital maps. To assure reliable operation, the function itself, its performance and the effect of its input parameters was simulatively evaluated before it was validated on real vehicles. In this paper we demonstrate how to adequately parameterize and evaluate such a TIS. We find feasible values for the input parameters for the creation of self-generated maps to ensure solid operation of the function. We further contribute to the community and other projects using similar TIS deployments by introducing applicable metrics for TIS evaluation in general and show our findings for the simTD research project. © 2011 IEEE.

关键词： Function evaluation

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Cooperative Awareness at Low Vehicle Densities: How Parked Cars Can Help See through Buildings

Cooperative Awareness at Low Vehicle Densities: How Parked C...

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2011 IEEE Global Telecommunications Conference - GLOBECOM 2011

作者： David Eckhoff Christoph Sommer Reinhard German Falko Dressler Computer Networks and Communication Systems Department of Computer Science University of Erlangen Germany Computer and Communication Systems Institute of Computer Science University of Innsbruck Austria

Many safety applications in Intelligent Transportation systems (ITS) require vehicles to be aware of the presence of nearby cars, but - especially in urban and suburban regions - buildings and other obstacles may block radio transmissions. In the literature, multi-hop relaying by neighboring cars has been demonstrated to perform well at disseminating safety broadcasts in the presence of obstacles. At night, in areas with low traffic density, or when the penetration rate of Car-2-X devices is low, however, there are likely to be too few relaying cars available. This again leads to the problem that vehicles which are not in line-of-sight frequently cannot be sensed either. To the best of our knowledge, we are the first to help overcome this problem by utilizing parked cars as relay nodes. We study the effectiveness and the necessity of this approach with the help of extensive simulative studies and real life experiments. We show how, for scenarios with few equipped cars, the utilization of parked cars proves crucial to support safety applications. When disseminating safety critical events in a realistic scenario, parked cars can increase cooperative awareness by over 40% in total.

关键词： Vehicles Peer to peer computing Relays Safety Buildings Attenuation High definition video

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A computationally inexpensive empirical model of IEEE 802.11p radio shadowing in urban environments

A computationally inexpensive empirical model of IEEE 802.11...

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Annual Conference on Wireless On Demand Network systems and Services (WONS)

作者： Christoph Sommer David Eckhoff Reinhard German Falko Dressler Computer Networks and Communication Systems Department of Computer Science University of Erlangen Germany

We present a realistic, yet computationally inexpensive simulation model for IEEE 802.11p radio shadowing in urban environments. Based on real world measurements using IEEE 802.11p/DSRC devices, we estimated the effect that buildings and other obstacles have on the radio communication between vehicles. Especially for evaluating safety applications in the field of Vehicular Ad Hoc networks (VANETs), stochastic models are not sufficient for evaluating the radio communication in simulation. Motivated by similar work on WiFi measurements, we therefore created an empirical model for modeling buildings and their properties to accurately simulate the signal propagation. We validated our model using real world measurements in a city scenario for different types of obstacles. Our simulation results show a very high accuracy when compared with the measurement results, while only requiring a marginal overhead in terms of computational complexity.

关键词： Buildings Computational modeling Mathematical model Shadow mapping Attenuation Predictive models Loss measurement

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Self-healing optical access networks (SHOAN) operated by optical switching technologies

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IEEE Transactions on Network and Service Management 2011年第3期8卷 234-244页

作者： Huang, Anpeng Liu, Siyu Xie, Linzhen Chen, Zhangyuan Mukherjee, Biswanath State Key Lab. of Advanced Optical Communication Systems and Networks China Wireless Communications Lab. PKU-UCLA Joint Research Institute Peking University Beijing 100871 China Department of Computer Science University of California Davis United States

An optical access network should offer low-cost reliable services to its end users. To address this problem, an optimal solution is needed which can turn an optical access architecture into a self-healing system. Hence, we propose the Self-Healing Optical Access Network (SHOAN), in which two or more optical access architectures are partners of each other, and they are interconnected by elementary optical crossbar switches into a simple mesh network. In SHOAN, the crossbar switches can keep each access architecture as an independent and closed system for only serving its own end users in normal state. But the crossbars become open in fault scenarios. Whenever a failure occurs in the network, the fault can be monitored and affected services can be recovered by the partner of the access architecture that is affected. Such an interconnected optical access network can withstand failures in its transmission paths, and recover network services in a self-healing way. Compared to existing solutions (e.g., dual-home architecture), illustrative examples demonstrate that SHOAN has many desirable properties: (1) it is robust because risks are disjointed, (2) it is reliable because service recovery is given top priority, and (3) it has low cost because redundant backup components are not necessary since the partner's resources act as backup resources. Analysis results show that SHOAN can minimize disruption duration and network cost for broadband access services. © 2011 IEEE.

关键词： Cost benefit analysis

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Near range pedestrian collision detection using bio-inspired visual neural networks

Near range pedestrian collision detection using bio-inspired...

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2011 7th International Conference on Natural Computation, ICNC 2011

作者： Belevskiy, Vladimir Yue, Shigang Computer Systems and Networks Department Bauman Moscow State Technical University Moscow Russia School of Computer Science Faculty of MHT University of Lincoln Lincoln LN6 7TS United Kingdom

ISBN: (纸本)9781424499533

New vehicular safety standards require the development of pedestrian collision detection systems that can trigger the deployment of active impact alleviation measures from the vehicle prior to a collision. In this paper, we propose a new vision-based system for near-range pedestrian collision detection. The low-level system uses a bio-inspired visual neural network, which emulates the visual system of the locust, to detect visual cues relevant to objects in front of a moving car. At a higher level, the system employs a neural-network classifier to identify dangerous pedestrian positions, triggering an alarm signal. The system was tuned via simulation and tested using recorded video sequences of real vehicle impacts. The experiment results demonstrate that the system is able to discriminate between pedestrians in dangerous and safe positions, triggering alarms accordingly. © 2011 IEEE.

关键词： Pedestrian safety

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Efficient free-space optical coupler into dielectric waveguide with great field enhancement

Efficient free-space optical coupler into dielectric wavegui...

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2011 International Conference on Information Photonics and Optical communications, IPOC 2011

作者： Li, Guangyuan Li, Kun Cai, Lin Xu, Anshi State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University 5# Yiheyuan Road Haidian Beijing 100871 China

ISBN: (纸本)9781467307130

We propose an efficient optical coupler to launch free-space signals into a dielectric dielectric waveguide via plasmonic structures with great field enhancement. A plasmonic concentrator composed of a subwavelength slit surround by periodic grooves is used to access and collect free-space light. The transmitted light is then unidirectional directed into a dielectric waveguide with a plasmonic Bragg reflector and a directional coupler. The free-space optical coupler is useful as it combines the plasmonic structure for optical signal access in subwavelength scale with the ultra-low loss dielectric waveguide for long-distance signal transmission and processing making use of nonlinearity. © 2011 IEEE.

关键词： Plasmonics

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Simultaneous slow and fast light

Simultaneous slow and fast light

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Optical Sensors, Sensors 2011

作者： Luo, Bin Guo, Hong CREAM Group State Key Laboratory of Advanced Optical Communication Systems and Networks Inst. of Quantum Electronics School of Electronics Engineering Computer Science Peking University Beijing 100871 China

Simultaneous slow and fast light requires rf field [Opt. Lett. 35, 64 (2010)], which is inconvenient. We suggest that the rf field can be replaced by lights and thus, the phenomena can be realized optically. © OS... 详细信息

ISBN: (纸本)9781557529138

关键词： Slow light

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Distributed Mass-Spring-Relaxation for Anchor-Free Self-Localization in Sensor and Actor networks

Distributed Mass-Spring-Relaxation for Anchor-Free Self-Loca...

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International Conference on computer communications and networks (ICCCN)

作者： Juergen Eckert Felix Villanueva Reinhard German Falko Dressler Computer Networks and Communication Systems Department of Computer Science University of Erlangen Germany Computer Architecture and Networks School of Computer Science University of Castilla La Mancha Spain Institute of Computer Science University of Innsbruck Austria

We present a fully self-organizing approach for creating and maintaining a reference coordinate system for self-localization in Sensor and Actor networks (SANETs). GPS technology has become a de facto standard for outdoor localization, however, self-localization in GPS denied scenarios is still extremely challenging. Typically, anchor nodes or global state information are used to update the nodes' location information. In contrast, we present a fully self-organizing strategy to generate a distributed reference coordinate system. In particular, we use autonomous robot systems to span and maintain this coordinate system. In particular, we investigated the capabilities of the Mass-Spring-Relaxation (MSR) algorithm, which is frequently used for fault-tolerant and robust localization. Unfortunately, this algorithm needs certain globally valid state information. We extended the MSR algorithm in two ways: First, we made the algorithm independent of a priori global knowledge, and, secondly, we provide extensions that make the algorithm more reliable and robust, and to reduce the number of necessary information exchanges between the nodes. As can be seen from the simulation results, our advanced MSR is very accurate and clearly outperforms the classical MSR for increasing network sizes. We also validated the simulations in an experimental setting. The obtained results confirm the very high localization accuracy.

关键词： Springs Equations Distance measurement Artificial neural networks Hardware Robot sensing systems Accuracy

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Magnetically induced simultaneous slow and fast light by phase control

Magnetically induced simultaneous slow and fast light by pha...

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Slow and Fast Light, Slow_Fast 2011

作者： Luo, Bin Guo, Hong CREAM Group State Key Lab. of Advanced Optical Communication Systems and Networks Inst. of Quantum Electronics School of Electronics Engineering and Computer Science Peking University Beijing 100871 China

A-type atom coupled by additional driving light and radio frequency (RF) field can generate controllable simultaneous slow and fast light at two frequencies. Distortions by radiative dampings are discussed and compens... 详细信息

ISBN: (纸本)9781557529138

关键词： Slow light

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