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45 results on '"Kwok, C.H."'

24. Link Reliability Improvement for Optical Wireless Communication Systems With Temporal-Domain Diversity Reception.

Author

Kwok, C.H., Penty, R.V., and White, I.H.

Abstract

We experimentally demonstrate a simple temporal- domain diversity reception (TD-DR) scheme to enhance the reliability of optical wireless transmission links corrupted by atmospheric turbulence (AT) effects. Both nonreturn-to-zero and Manchester encoded on-off-keying modulation schemes are studied in laboratory environments at a 1.25-Gb/s data rate. AT effects are emulated as a slowly varying log-normal intensity variation for the received signal. System bit-error ratio is tracked for the performance evaluation, and results show that the outage probability due to the AT-induced intensity fluctuation for a 1.25-Gb/s link using Manchester coding is reduced from 3.2%plusmn0.1% to <0.1%, when the TD-DR is employed. [ABSTRACT FROM PUBLISHER]

Published
2008
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25. Simultaneous 4 × 10 Gb/s NRZ-to-RZ Modulation Format Conversion in Nonlinear Optical Loop Mirror With a Photonic Crystal Fiber.

Author

Kwok, C.H. and Chinlon Lin

Abstract

Orthogonal cross-phase-modulation (XPM) scheme in a nonlinear optical loop mirror (NOLM) is proposed to simultaneously convert four synchronized 10-Gb/s nonreturn-to-zero signals into return-to-zero (RZ) format. Modulation format conversion is achieved by using a synchronized optical control pulse train as the pulse carver in a NOLM. The control pulse train and the targeted signals are orthogonal in their states of polarization. This orthogonal nonlinear interaction substantially suppresses the undesirable four-wave mixing (FWM) induced crosstalk in the multichannel operation. Experimental demonstration of the proposed scheme shows that the suppression of the generated FWM idler is >26 dB. Error-free operation is achieved for the four converted 10-Gb/s RZ signals in a single NOLM by sharing the nonlinear XPM effect induced by the control pulse train. [ABSTRACT FROM PUBLISHER]

Published
2007
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26. The characteristics, perceptions and personalities of women seeking a reversal of their tubal sterilization

Author

Abraham, Suzanne, Jansen, Robert, Fraser, Ian S., and Kwok, C.H. Michael

Abstract

The characteristics, perceptions and personalities of women who had sought a reversal of a tubal sterilization procedure and those who had not were studied. Women were more likely to request reversal of a tubal sterilization if they were less than 30 years old at the time of the operation or if they had changed their marital status since sterilization. Women who had undergone a tubal sterilization and later sought a reversal stated that at the time of the procedure they did not believe that their family was complete; they had not had sufficient time to consider the implications of undergoing a tubal sterilization; they felt that they had been “pressured” by their partner to be sterilized; and they perceived the potential to have a child as important, even if they did not wish for further children. Women who had had a tubal sterilization performed within a few days of childbirth for “health or medical reasons” and sought a reversal no longer believed that the reasons were valid. In spite of the inclusion of women who had changed their minds about tubal sterilization, no differences were detected in psychometric measures of personality and mental health between our groups. The findings of the survey confirm that a woman should make up her own mind whether or not to undergo a tubal sterilization, and the operation should not be available “on demand”. Ways of overcoming the problem are suggested.

Published
1986
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