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- da Silva, Edson P., et al.
(författare)
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Combined Optical and Electrical Spectrum Shaping for High-Baud-Rate Nyquist-WDM Transceivers
- 2016
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Ingår i: IEEE Photonics Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0655. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the benefits and limitations of optical time-division multiplexing (OTDM) techniques based on the optical generation of a periodic train of sinc pulses for wavelength-division multiplexing (WDM) transmission at high baud rates. It is shown how the modulated OTDM spectrum bandwidth is related to the optical comb parameters and the pulse shaping of the modulating waveforms in the electrical domain. Such dependence may result in broadening of the modulated spectra, which can degrade the performance of Nyquist-WDM systems due to interchannel crosstalk penalties. However, it is shown and experimentally demonstrated that the same technique of optical pulse train generation can be allied with digital pulse shaping to improve the confinement of the modulated spectrum toward the Nyquist limit independently of the number of OTDM tributaries used. To investigate the benefits of the proposed approach, we demonstrate the first WDM Nyquist-OTDM signal generation based on the periodic train of sinc pulses and electrical spectrum shaping. Straight line transmission of five 112.5-Gbd Nyquist-OTDM dual-polarization quadrature phase-shift keying (QPSK) channels is demonstrated over a dispersion uncompensated link up to 640 km, with full-field coherent detection at the receiver. It is shown that such a design strategy effectively improves the spectral confinement of the modulated OTDM signal, providing a minimum intercarrier crosstalk penalty of 1.5 dB in baud-rate-spaced Nyquist-WDM systems.
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- Kpeglo, D. O., et al.
(författare)
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Radiochemical characterization of produced water from two production offshore oilfields in Ghana
- 2016
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X. ; 152, s. 35-45
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Tidskriftsartikel (refereegranskat)abstract
- Produced water from two Ghanaian offshore production oilfields has been characterized using alpha spectrometry after radiochemical separation, non-destructive gamma spectrometry and ICP-MS and other complimentary analytical tools. The measured concentrations of main NORM components were in the range of 6.2-22.3 Bq.L-1, 6.4-35.5 Bq.L-1, and 0.7-7.0 Bq.L-4 (f)or Ra-226, Ra-228 and Ra-224 respectively. A good correlation between several physico-chemical parameters and radium isotopes was observed in each production oilfield. The radium concentrations obtained in this study for produced water from the two oilfields of Ghana are of radiological importance and hence there may be the need to put in place measures for future contamination concerns due to their bioavailability in the media and bioaccumulation characteristics. The results will assist in critical decision making for future set up of appropriate national guidelines for the management of NORM waste from the emerging oil and gas industry in Ghana. (C) 2015 Elsevier Ltd. All rights reserved.
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