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21.
Medard M. Lumetta S. Liuyang Li 《Selected Areas in Communications, IEEE Journal on》2002,20(4):822-833
We describe an architecture for an optical local area network (LAN) or metropolitan area network (MAN) access. The architecture allows for bandwidth sharing within a wavelength and is robust to both link and node failures. The architecture can be utilized with an arbitrary, link-redundant mesh network (node-redundancy is necessary only to handle all node failures), and assumes neither the use of a star topology nor the ability to embed such a topology within the physical mesh. Reservation of, bandwidth is performed in a centralized fashion at a (replicated) head end node, simplifying the implementation of complex sharing policies relative to implementation on a distributed set of routers. Unlike a router, however, the head end does not take any action on individual packets and, in particular, does not buffer packets. The architecture thus avoids the difficulties of processing packets in the optical domain while allowing for packetized shared access of wavelengths. We describe the route construction scheme and prove its ability to recover from single link and single node failures, outline a flexible medium access protocol and discuss the implications for implementing specific policies, and propose a simple implementation of the recovery protocol in terms of state machines for per-link devices 相似文献
22.
Analysis on the effectiveness of the 20-H rule for printed-circuit-board layout to reduce edge-radiated coupling 总被引:1,自引:0,他引:1
Montrose M.I. Er-Ping Li Hong-Fang Jin Wei-Liang Yuan 《Electromagnetic Compatibility, IEEE Transactions on》2005,47(2):227-233
This paper presents the quantified study of the electromagnetic radiation mechanism of the 20-H rule using a numerical approach that has not yet been systematically addressed. The 20-H rule is a rule-of-thumb layout technique recommended to minimize radiated fields propagating from the edges of a printed circuit board (PCB) coupling onto nearby structures. Propagating electromagnetic fields may corrupt adjacent cable assemblies, sheet metal enclosures, and aperture openings. The magnitude of this design rule is investigated using the full-wave finite-difference time-domain (FDTD) method. An analysis on whether benefits exist from use of this rule is examined and under what conditions the rule is valid when correctly implemented. The purpose of this paper is to provide insight into the validity of the 20-H rule, recognizing that every PCB will have different simulation results. FDTD is used to capture a snapshot view of field propagation. This view allows one to determine the validity of the 20-H rule at a single point of time within a dynamic structure and what may be expected when digital components are finally added to a PCB assembly, which generally negates simulated results. 相似文献
23.
Hong Wang Rong Zeng Xiuping Li 《Microwave Theory and Techniques》2005,53(2):564-570
In this paper, RF noise in 0.18-mum NMOSFETs concerning the contribution of carrier heating and hot carrier effect is characterized and analyzed in detail via a novel approach that modulates the channel carrier heating and number of hot carriers using body bias. We confirm qualitatively a negligible role of hot carrier effect on the channel noise in deep-submicrometer MOSFETs. For a device under reverse body bias (Vb), even though the increase in hot carrier population is clearly characterized by dc measurements, the device high-frequency noise is found to be irrelevant to the increase in the channel hot carriers. Experimental results show that the high-frequency noise is slightly reduced with the increase in |Vb|, and can be qualitatively explained by secondary effects such as the suppression of nonequilibrium channel noise and substrate induced noise. The reduction of NFmin and Rn with the increase in |Vb| may provide a possible methodology to finely adjust the device high-frequency noise performance for circuit design 相似文献
24.
X Y Liu C J Li 《Science in China. Series B, Chemistry, life sciences & earth sciences》1989,32(10):1215-1223
To further evaluate the causality between endogenous pyrogen (EP)-induced fever and cyclic adenosine-3',5'-monophosphate (cyclic AMP) level, the effects of sodium salicylate (SS) on the febrile response and increased levels of cyclic AMP in both cerebrospinal fluid (c.s.f.) and plasma during EP-induced fever in rabbits were observed. The results suggest that cyclic AMP is probably involved in the central mediation of EP-induced fever and that increased concentration of cyclic AMP in c.s.f. associated with EP-induced fever is not the result of temperature elevation but appears to be caused by the increased synthesis in the central nervous system. In addition it is confirmed that blood is impossibly a contributory source of increased cyclic AMP in c.s.f. during EP fever, and that SS may act subsequent to the increase in cyclic AMP. 相似文献
25.
Lifang Li Jindal N. Goldsmith A. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2005,51(4):1326-1347
We derive the outage capacity region of an M-user fading multiple-access channel (MAC) under the assumption that both the transmitters and the receiver have perfect channel side information (CSI). The outage capacity region is implicitly obtained by deriving the outage probability region for a given rate vector. Given a required rate and average power constraint for each user, we find a successive decoding strategy and a power allocation policy that achieves points on the boundary of the outage probability region. We discuss the scenario where an outage must be declared simultaneously for all users (common outage) and when outages can be declared individually (individual outage) for each user. 相似文献
26.
Yanping Li Jinzhong Yu Shaowu Chen 《Photonics Technology Letters, IEEE》2005,17(8):1641-1643
A rearrangeable nonblocking 4/spl times/4 thermooptic silicon-on-insulator waveguide switch matrix at 1.55-/spl mu/m integrated spot size converters is designed and fabricated for the first time. The insertion losses and polarization-dependent losses of the four channels are less than 10 and 0.8 dB, respectively. The extinction ratios are larger than 20 dB. The response times are 4.6 /spl mu/s for rising edge and 1.9 /spl mu/s for falling edge. 相似文献
27.
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29.
An experimental study of an optical burst switching network based on wavelength-selective optical switches 总被引:1,自引:0,他引:1
Li Xinwan Chen Jianping Wu Guiling Wang Hui Ye Ailun 《Communications Magazine, IEEE》2005,43(5):S3-10
In this article we report the system structure and test results of an experimental optical burst switching network with three edge router's and one core node. Wavelength-selective switches developed for this system and their characteristics are depicted. The implementation and performance of our new scheme for the just-in-time protocol are described. We also report experimental results of FTP and VOD services on this system. Some parameters, including traffic rate, average burst data length, and assembly time, are studied. 相似文献
30.
本文讨论了每个元都有幂等元作为右单位元的左消半群与幂单半群N的Schuzenberger积M◇N的ρ类,证明了这种半群M与N的Schuzenberger积M◇N的ρ类是右E一半适合半群和弱E-headged半群. 相似文献