1,720,961 research outputs found
Meeting Optical Qos Requirements With Reduced Complexity In Dynamic Wavelength Assignment
No full textPhysical layer impairments may require highly complex implementations of the control plane in dynamic networks with Quality of Service (QoS) constraints. In order to alleviate this problem, we propose that dynamic wavelength assignment should be based on the elementary First-Fit (FF) algorithm using off-line optimized priority lists. It is shown that this may significantly reduce the effects of physical impairments with no additional computational cost for the control of dynamic networks. A simple metric is proposed to evaluate optical QoS taking the performance of the network as a whole. Different heuristics are presented and evaluated. Results show that there are particular lists capable of reducing in four orders of magnitude the probability of FWM impacting network performance. © 2004 IEEE.331333Ramamurthy, B., Datta, D., Feng, H., Heritage, J.P., Mukherjee, B., Impact of transmission impairments on the teletraffic performance of wavelength-routed optical networks (1999) J. Ligthwave Technology, 17, pp. 1713-1723. , OctAli, M., Tancevski, L., Impact of polarization-mode dispersion on the design of wavelength-routed networks (2002) Photonics Technology Letters, 14, pp. 720-722. , MayFonseca, I.E., Ribeiro, M.R.N., Almeida Jr., R.C., Waldman, H., Preserving global optical QoS in FWM impaired dynamic networks (2004) Electronics Letters, 40, pp. 191-192. , FebXu, B., Brandt-Pearce, M., Comparison of FWM- And XPM-induced crosstalk using the Volterra series transfer function method (2003) J. Ligthwave Technology, 21, pp. 40-53. , JanFonseca, I.E., Almeida Jr., R.C., Ribeiro, M.R.N., Waldman, H., Algorithms for FWM-aware routing and wavelength assignment (2003) Proc. IEEE IMOC'03, 2, pp. 707-713. , SepInoue, K., A simple expression for optical FDM network scale considering fiber FWM and optical amplifier noise (1995) J. Ligthwave Technology, 13, pp. 856-861. , MayForghieri, F., Tkach, R.W., Chraplyvy, A.R., Marcuse, D., Reduction of four-wave mixing crosstalk in WDM systems using unequally spaced channels (1994) Photonics Technology Letters, 6, pp. 754-756. , Jun(2002) Spectral Grids for WDM Application: DWDM Frequency Grid, , ITU-T Rec. G.694.1, Ju
Optical Buffer Modelling For Performance Evaluation Considering Any Packet Inter-arrival Time Distribution
No full textIn this paper we present an exact analytical model for the FIFO delay-line buffer in an asynchronous network scenario considering that packets arrive to the buffer following any inter-arrival time process. The model enables us to study the impact that different inter-arrival distributions have on the buffer performance and design process. The accuracy of the model is compared with simulations for Deterministic, Uniform, Exponential and Weibull inter-arrival time distributions. Then, the effects of these distributions, input load and delay line spacings on the buffer performance are investigated.317711775Hunter, D.K., Chia, M.C., Andonovic, I., Buffering in optical packet switches (1998) Journal on Lightwave Technologies, 16, pp. 2081-2094. , DecemberCallegati, F., Optical buffers for variable length packets (2000) IEEE Communication Letters, 4 (9), pp. 292-294. , SeptemberLaevens, K., Bruneel, H., Analysis of a single-wavelength optical buffer (2003) IEEE INFOCOM 2003, , AprilAlmeida Jr., R.C., Pelegrini, J.U., Waldman, H., Delay-line buffer modeling for asynchronous optical networks (2003) Proceedings of SPIE Opticomm '03, , Dallas, TX. USAOctoberXu, L., Perros, H.G., Rouskas, G., Techniques for optical packet switching and optical burst switching (2001) IEEE Communications Magazine, , JanuaryCallegati, F., Corazza, G., Raffaelli, C., Exploitation of DWDM for optical packet switching with quality of service guarantees (2002) IEEE Journal on Selected Areas in Communications, 20 (1), pp. 190-201. , JanuaryWaldman, H., Almeida Jr., R.C., Pelegrini, J.U., An infinite granularity bound on the performance of delay-line buffering (2003) ONDM 2003, , Budapest, FebruaryTancěvski, L., Ge, A., Castañóon, G., Tamil, L., A new scheduling algorithm for asynchronous, variable length IP traffic incorporating void filling (1999) Proc. of Optical Fiber Communications Conference - OFC'99, , paper ThM7. San Diego. FebruaryTancěvski, L., Yegnanarayanan, S., Castañón, G., Tamil, L., Masetti, F., McDermott, T., Optical routing of asynchronous, variable length packets (2000) IEEE Journal on Selected Areas in Communications, 18 (10). , Octobe
Diffserv Implementation By A Balking Mechanism In Delay-line Buffering
No full textIn this paper we address the problem of providing delay-line buffers with the capability to differentiate services in optical packet switching networks. A simple and efficient policy for acceptance and discarding of optical packets is proposed and its analytical model is presented. The model enables the exact calculation of packet loss probability and average delay for Poisson arrivals and any packet length distribution. The buffer performance as predicted by the model is compared with simulations for Pareto packet length distribution.526842688Xiao, X., Ni, L.M., Internet QoS: A big picture (1999) IEEE Network, 13, pp. 8-18. , MarYoo, M., Qiao, C., Dixit, S., QoS performance of optical burst switching in IP-over-WDM networks (2000) EEE J. Select. Areas Commun., Special Issue on Protocols for the Next Generation Optical Internet, 18, pp. 2062-2071. , OctHunter, D.K., Chia, M.C., Andonovic, I., Buffering in optical packet switches (1998) J. Lightwave Technol., 16, pp. 2081-2094. , DecXu, L., Perros, H.G., Rouskas, G., Techniques for optical packet switching and optical burst switching (2001) IEEE Commun. Mag., 39, pp. 136-142. , JanCallegati, F., Corazza, G., Raffaelli, C., Exploitation of DWDM for optical packet switching with quality of service guarantees (2002) IEEE J. Select. Areas Commun., 20, pp. 190-201. , JanCallegati, F., Optical buffers for variable length packets (2000) IEEE Commun. Lett., 4, pp. 292-294. , SeptWaldman, H., Almeida Jr., R.C., Pelegrini, J.U., An infinite granularity bound on the performance of delay-line buffering (2003) Proc. of the 7th IFIP Optical Network Desing and Modelling Conference (ONDM'03), pp. 1187-1200. , Budapest, Hungary, FebTancěvski, L., Ge, A., Castañón, G., Tamil, L., A new scheduling algorithm for asynchronous, variable length IP traffic incorporating void filling (1999) Proc. of Optical Fiber Communications Conference (OFC'99), pp. 180-182. , San Diego, USA, FebTancěvski, L., Yegnanarayanan, S., Castañón, G., Tamil, L., Masetti, F., McDermott, T., Optical routing of asynchronous, variable length packets (2000) IEEE J. Select. Areas Commun., 18, pp. 2084-2093. , OctGross, D., Harris, C.M., (1998) Fundamentals of Queueing Theory, 3rd Ed., , Wiley-Interscienc
Delay-line Buffer Modeling For Asynchronous Optical Networks
No full textIn this paper we develop an analytical model for the FIFO delay-line buffer in asynchronous optical networks with any packet length distribution, under the assumption that arrivals are Poissonian. We consider that the incoming traffic is distributed among an infinite number of inputs (Aloha traffic) and show that this consideration represents very suitably a real system. The model enables the exact calculation of packet loss probability and average delay, which makes it a very powerful tool for performance evaluation and planning/dimensioning of networks that use this kind of contention resolution technique. The buffer performance as predicted by the model is compared with simulations and discussed for some packet length distributions.5285381391Hunter, D.K., Chia, M.C., Andonovic, I., Buffering in Optical Packet Switches (1998) Journal on Lightwave Technologies, 16, pp. 2081-2094. , DecemberGambini, P., Transparent Optical Packet Switching: Network architecture and demonstrators in the KEOPS project (1998) IEEE Journal on Selected Areas in Communications, 16 (7), pp. 1245-1259. , Invited paperChlamtac, I., CORD: Contention Resolution by Delay Lines (1996) IEEE Journal on Selected Areas in Communications, 14 (5), pp. 1014-1029Xu, L., Perros, H.G., Rouskas, G., Techniques for Optical Packet Switching and Optical Burst Switching (2001) IEEE Communications Magazine, , JanuaryHansen, P.B., Danielsen, S.L., Stubkjaer, K.E., Optical Packet Switching without Packet Alignment (1998) Proc. of ECOC'98, , Madrid, Spain, SeptemberCallegati, F., Corazza, G., Raffaelli, C., Exploitation of DWDM for Optical Packet Switching with Quality of Service Guarantees (2002) IEEE Journal on Selected Areas in Communications, 20 (1), pp. 190-201. , JanuaryCallegati, F., Optical Buffers for Variable Length Packets (2000) IEEE Communication Letters, 4 (9). , SeptemberTancevski, L., Ge, A., Castanon, G., Tamil, L., A New Scheduling Algorithm for Asynchronous, Variable Length IP Traffic Incorporating Void Filling (1999) Proc. of Optical Fiber Communications Conference - OFC'99, , paper ThM7, San Diego, FebTancevski, L., Yegnanarayanan, S., Castañon, G., Tamil, L., Masetti, F., McDermott, T., Optical Routing of Asynchronous, Variable Length Packets (2000) IEEE Journal on Selected Areas in Communications, 18 (10). , OctoberWaldman, H., Almeida Jr., R.C., Pelegrini, J.U., An Infinite Granularity Bound on the Performance of Delay-Line Buffering (2003) Proceedings of ONDM 2003, the 7th IFIP Working Conference on Optical Network Design & Modelling, pp. 1187-1200. , Budapest, FebruaryCrovella, M.E., Bestavros, A., Self-similarity in World Wide Web Traffic: Evidence and possible causes (1997) IEEE/ACM Trans. Networking, 5 (6), pp. 835-846. , De
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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