1,720,967 research outputs found
Implementation Of A Radio Over Fiber System In A Geographically-distributed Optical Network
No full textThis work presents an implementation of a Radio over Fiber system based on IEEE 802.15.4 standard, in a geographically-distributed optical network, called KyaTera. The input signal was launched into hundreds of kilometers from KyaTera Network under real conditions of temperature, pressure, humidity and wind. Experimental results show no performance degradation of the transmitted radio frequency signal.1639641Jia, Z., Yu, J., Ellinas, G., Gee-Kung, C., Key enabling technologies for optical wireless networks optical millimeter wave generation wavelength reuse and architecture (2007) J. of Light. Tech., 25, pp. 3452-3471Chang, S.C.W., (2002) RF Photonic Technology in Optical Fiber Links, , Cambridge University Presswww.kyatera.fapesp.brMarconi, J.D., Callegari, F.A., Abbade, M.L.F., Fragnito, H.L., Field trial evaluation of the Q-factor penalty introduced by fiber four-wave mixing wavelength converters (2008) Opt. Communications, , In Pres
Optical Labelling Through Parametric Amplification
No full textA new all-optical technique to label on-off keyed (OOK) payload signals is experimentally analysed. Such all-optical operation is accomplished by using a fibre optical parametric amplifier (FOPA) with the pump modulated by label information to amplify the OOK payload; as a result, the signal at the output of the FOPA becomes a ternary-amplitude optical packet (TAOP). It is shown that the technique may generate TAOPs with different power level distributions. Furthermore, the TAOP was propagated through a link on a field-trial network. The obtained eye-penalties are inferior to 0.7 dB and suggest that the optical packet could be properly propagated through metropolitan area networks. © 2011 IEEE.Vetenskap och Konst (KTH),acreo,Instytut Lacznosci - Panstwowy Instytut Badawczy,Vetenskapsradet,STAD-StockholmRamaswami, R., Sivarajan, K.N., (2002) Optical Networks: A Practical Perspective, , New York: Academic PressBlumenthal, D.J., All-optical label swapping networks and technologies (2000) IEEE J. Light. Tech., 18, pp. 2058-2075. , DecChi, N., Transmission and transparent wavelength conversion of an optically labeled signal using ASK/DPSK orthogonal modulation (2003) IEEE Phot. Tech. Lett., 15, pp. 760-762. , MayAbbade, M.L.F., Quaternary optical packets generated by fiber four-wave mixing (2006) IEEE Phot. Tech. Lett., 18 (2), pp. 331-333. , JanKoonen, T., Sulur, S., Monroy, I., Jennen, J., Waardt, H., Optical labeling of packets in IP-over-WDM networks (2002) Proc. ECOC 2002, , Copenhagen, Denmark. Paper 5.5.2Abbade, M.L.F., Ternary amplitude optical packets generated by parametric amplification (2007) ICTON 2007, 4, pp. 256-259Marhic, M.E., Kagi, N., Chiang, T.-K., Kazovsky, L.G., Broadband fiber optical parametric amplifiers (1996) Opt. Lett., 21, pp. 573-575Fagotto, E.A.M., Abbade, M.L.F., All-optical demultiplexing of 4-ASK optical signals with four-wave mixing optical gates (2010) Optics Communications, 283, pp. 1102-1109http://www.kyatera.fapesp.br/Walklin, S., Conradi, J., Multilevel signaling for increasing the reach of 10 Gb/s lightwave systems (1999) IEEE J. Light. Tech., 17 (11), pp. 2235-224
Radio Over Fiber System Applied To Ieee 802.15.4 Standard
No full textWe have experimentally applied the Radio over Fiber (RoF) technology to a Wireless Sensor Network (WSN) based on IEEE 802.15.4 standard. Numerical simulations and experimental results demonstrate a successful implementation of a RoF technology operating at 2.4 GHz band over at least 160 km of a geographically-distributed optical network. ©2009IEEE.838840Jia, Z., Yu, J., Ellinas, G., Chang, G.-K., Key enabling technologies for optical wireless networks optical millimeter wave generation wavelength reuse and architecture (2007) Journal of Lightwave Technology, 25, pp. 3452-3471Cerqueira S Jr., A., Valente E Silva, D.C., Fortes, M.A.Q.R., Da Silva, L.F., Branquinho, O.C., Abbade, M.L.F., Performace analysis of a radio over fiber system based on IEEE 802.15.4 standard in a real optical network (2009) Microwave and Optical Technology Letters, 51, pp. 1876-1879William, S., Chang, C., (2002) RF Photonic Technology in Optical Fiber Links, , Cambridge University Presswww.kyatera.fapesp.brMarconi, J.D., Cerqueira S Jr., A., Robinson, J.T., Sherwwod-Droz, N., Okawachi, Y., Hernández-Figueroa, H.E., Lipson, M., Fragnito, H.L., Performance investigation of microphotonic-silicon devices in a field-trial all-optical network (2009) Optics Communications, 282, pp. 849-855Ma, J., Yu, J., Yu, C., Xin, X., Zeng, J., Chen, L., Fiber Dispersion Influence on Transmission of the Optical Millimeter-Waves Generated Using LN-MZM Intensity Modulation (2007) Journal of Ligthwave Technology, 25, pp. 3244-3256. , NovemberNovak, D., Hybrid Fiber Radio - The Application of Photonic Links in Wireless Communication Systems Optical Fiber Communications Conference, SC 217, 200
Optical Amplitude Multiplexing Through Four-wave Mixing Ill Optical Fibers
No full textWe propose a new optical amplitude multiplexing technique that consists of merging two wavelength multiplexed ON-OFF keying (OOK) signals into a single quaternary amplitude shift keying signal. This technique is based on four-wave mixing in a single-mode optical fiber and requires power offset from the OOK signals. Simulation results indicate that the multiplexing may be performed between signals of the same or different bit rates. As a consequence, the proposed technique may be used not only for increasing spectral efficiency but also for optical labeling. © 2005 IEEE.171151153Ono, T., Yano, Y., "Key technologies for terabit/second WDM systems with high spectral efficiency of over 1 bit/s/Hz" (1998) IEEE Photon. Technol. Lett., 34 (11), pp. 2080-2088. , NovRamaswami, R., Sivarajan, K.N., (2002) Optical Networks: A Practical Perspective, pp. 249-250. , 2nd ed. New York: AcademicYonenaga, K., Kuwuano, S., Norimatsu, S., Shibata, N., "Optical duobinary transmission system with no receiver sensitivity degradation" (1995) Electron. Lett., 31 (4), pp. 302-303Walklin, S., Conradi, J., "Multilevel signaling for increasing the reach of 10 Gb/S lightwave systems" (1999) J. Lightw. Technol., 17 (11), pp. 2235-2248. , NovIdler, W., Franz, B., Schlump, D., Wedding, B., Ramos, A.J., "Field trial at 40 Gbit/s over 28.6 km and 86 km of standard singlemode fiber using quaternary dispersion supported transmission" (1998) Electron. Lett., pp. 2425-2426. , DecAvlonitis, N.S., Yeatman, E.M., "Performance of 4-ary ASK for optical communication systems in dispersive, nonlinear environments" (2003) 8th IEEE High Frequency Postgraduate Colloquium, pp. 56-59. , Belfast, U.KAbbade, M.L.F., "Contribuição para o estudo de não-linearidades em fibras ópticas monomodo" (2001), Ph.D. Thesis, UNICAMP, Brazil, (Portuguese)Fonseca, I.E., Moschim, E., Abbade, M.L.F., "Optical multiplexing through FWM in highly nonlinear fibers: A novel device" (2002) Int. Telecommun. Symp., , Natal, BrazilAgrawal, G.P., (2001) Nonlinear Fiber Optics, , 3rd ed. San Diego, CA: AcademicShibata, N., Braun, R.P., Waarts, R.G., "Phase-mismatch dependence of efficiency of wave generation through four-wave mixing in a single-mode optical fiber" (1987) IEEE J. Quantum Electron., QE-23 (7), pp. 1205-1210. , JulCheng, Y., Snyder, A.W., "Four-photon parametric mixing in optical fibers: Effect of pump depletion" (1989) Opt. Lett., 14 (1), pp. 87-89. , Ja
Load balancing in fixed-routing optical networks with weighted ordering heuristics
Full text linkIn this paper we show that the adoption of a simple weighted ordering heuristic strategy to find fixed shortest path routes in a topology can improve load-balancing and, consequently, network performance. We compared our fixed routing strategies against the k-shortest paths (k-SP) fixed-alternate routing strategy for three different mesh topologies considering fixed grid networks (FGNs) and elastic optical networks (EONs). The results show that our simple fixed routing strategies can improve network performance for an optical network system, even compared with the fixed alternate routing and always using the shortest path. Results also show that such easy strategies act mainly in longer routes, increasing their probability of use and balancing the link load distribution
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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