The Experts below are selected from a list of 54996 Experts worldwide ranked by ideXlab platform

Manik Attygalle - One of the best experts on this subject based on the ideXlab platform.

  • extending optical transmission distance in fiber wireless links using Passive filtering in conjunction with optimized modulation
    Journal of Lightwave Technology, 2006
    Co-Authors: Manik Attygalle, Ampalavanapillai Nirmalathas
    Abstract:

    The authors demonstrate a simple Passive Technique for increasing the transmission distance in fiber wireless links through the application of a narrowband fiber Bragg grating (FBG) with high reflectivity (90-99%). They are applied in a conventional downstream link and also for the upstream in a wavelength-reused scheme. In the conventional nonwavelength-reused system, the grating is used to optimize the optical modulation depth and, hence, the receiver sensitivity in the downstream transmitted signal by reducing the power of the optical carrier before fiber transmission. In the wavelength-reused systems, the highly reflective FBGs can be effectively used at the base stations to recover a major portion of the optical carrier (as high as 99% of the downlink carrier) for uplink transmission from a weakly modulated downstream signal. In the latter case, the penalty in the downstream signal due to the large extraction of carrier power is partially offset by the sensitivity enhancement obtained in the filtering process. The authors present experimental results for the increased transmission performance for both the nonwavelength-reused and wavelength-reused scenarios. The increase in the sensitivity (at biterrorrate=10/sup -9/) in the nonwavelength-reused scheme for a given launch channel power that facilitates the increased transmission distance can be as large as 7 dB. The relative increase in the power margin for the upstream signal can be up to 4 dB in the wavelength-reused scheme. This would more than double the currently demonstrated transmission distances in such wavelength-reused systems without any optical amplification. The scheme is applicable to a wide range of radio frequencies and modulation depths.

  • Transmission improvement in fiber wireless links using fiber Bragg gratings
    IEEE Photonics Technology Letters, 2005
    Co-Authors: Manik Attygalle, Ampalavanapillai Nirmalathas, C. Lim, G.j. Pendock, G. Edvell
    Abstract:

    We demonstrate a simple, Passive Technique for significant improvement of transmission performance in fiber wireless links through the application of a narrow-band fiber Bragg grating. The grating is used to optimize the optical modulation depth in the transmitted signal by reducing the power of the optical carrier. We present experimental measurements that show improvements in receiver sensitivity (at bit-error rate =10/sup -9/) of up to 7 dB for both double- and single-sideband modulation schemes. The scheme is applicable to a wide range of radio frequencies and modulation depths.

Ampalavanapillai Nirmalathas - One of the best experts on this subject based on the ideXlab platform.

  • extending optical transmission distance in fiber wireless links using Passive filtering in conjunction with optimized modulation
    Journal of Lightwave Technology, 2006
    Co-Authors: Manik Attygalle, Ampalavanapillai Nirmalathas
    Abstract:

    The authors demonstrate a simple Passive Technique for increasing the transmission distance in fiber wireless links through the application of a narrowband fiber Bragg grating (FBG) with high reflectivity (90-99%). They are applied in a conventional downstream link and also for the upstream in a wavelength-reused scheme. In the conventional nonwavelength-reused system, the grating is used to optimize the optical modulation depth and, hence, the receiver sensitivity in the downstream transmitted signal by reducing the power of the optical carrier before fiber transmission. In the wavelength-reused systems, the highly reflective FBGs can be effectively used at the base stations to recover a major portion of the optical carrier (as high as 99% of the downlink carrier) for uplink transmission from a weakly modulated downstream signal. In the latter case, the penalty in the downstream signal due to the large extraction of carrier power is partially offset by the sensitivity enhancement obtained in the filtering process. The authors present experimental results for the increased transmission performance for both the nonwavelength-reused and wavelength-reused scenarios. The increase in the sensitivity (at biterrorrate=10/sup -9/) in the nonwavelength-reused scheme for a given launch channel power that facilitates the increased transmission distance can be as large as 7 dB. The relative increase in the power margin for the upstream signal can be up to 4 dB in the wavelength-reused scheme. This would more than double the currently demonstrated transmission distances in such wavelength-reused systems without any optical amplification. The scheme is applicable to a wide range of radio frequencies and modulation depths.

  • Transmission improvement in fiber wireless links using fiber Bragg gratings
    IEEE Photonics Technology Letters, 2005
    Co-Authors: Manik Attygalle, Ampalavanapillai Nirmalathas, C. Lim, G.j. Pendock, G. Edvell
    Abstract:

    We demonstrate a simple, Passive Technique for significant improvement of transmission performance in fiber wireless links through the application of a narrow-band fiber Bragg grating. The grating is used to optimize the optical modulation depth in the transmitted signal by reducing the power of the optical carrier. We present experimental measurements that show improvements in receiver sensitivity (at bit-error rate =10/sup -9/) of up to 7 dB for both double- and single-sideband modulation schemes. The scheme is applicable to a wide range of radio frequencies and modulation depths.

G. Edvell - One of the best experts on this subject based on the ideXlab platform.

  • Transmission improvement in fiber wireless links using fiber Bragg gratings
    IEEE Photonics Technology Letters, 2005
    Co-Authors: Manik Attygalle, Ampalavanapillai Nirmalathas, C. Lim, G.j. Pendock, G. Edvell
    Abstract:

    We demonstrate a simple, Passive Technique for significant improvement of transmission performance in fiber wireless links through the application of a narrow-band fiber Bragg grating. The grating is used to optimize the optical modulation depth in the transmitted signal by reducing the power of the optical carrier. We present experimental measurements that show improvements in receiver sensitivity (at bit-error rate =10/sup -9/) of up to 7 dB for both double- and single-sideband modulation schemes. The scheme is applicable to a wide range of radio frequencies and modulation depths.

Choi Woorak - One of the best experts on this subject based on the ideXlab platform.

  • Effects of surface morphological structure of a brown alga miyeok (Undaria pinnatifida) on sustainable drag reduction
    American Institute of Physics Inc., 2020
    Co-Authors: Lee, Sang Joon, Heo Seongkwang, Yoon, Gun Young, Seo Eunseok, Choi Woorak
    Abstract:

    Liquid-infused surfaces are a promising Passive Technique for frictional drag reduction. However, their practical application is limited by the easy depletion of the lubricant infused in the surface by external forces. Miyeok contains mucus on its surface, which induces a sustainable slippery surface under flow conditions. In this study, the effect of the surface morphological structures of miyeok on slippery characteristics was examined. The surface of miyeok has bump-like microstructures and tiny pores of mucilage gland cells with a re-entrant inlet configuration. A replica model of the miyeok surface was fabricated by adopting a molding process using polydimethylsiloxane. The miyeok replica model was dipped into a silicone oil solution to obtain a slippery surface property. The surface structures of fresh miyeok and the replica were checked by comparing their scanning electron microscopy images. A replica of a kelp surface was also fabricated by employing the same method. The heights of the surface microstructures of the miyeok replica were more uniform than those of the kelp replica. The sustainable drag reduction effect of the replica models' surfaces was assessed by a sessile drop method. The liquid-infused miyeok replica surface (LIMRS) showed better sustainability than other surfaces. The slippery properties of the LIMRS were examined by measuring slip length and pressure drop. The drag reduction rates measured by the two methods were approximately 24% and 19%. The present results would be helpful for understanding the effects of the surface structure of natural miyeok on sustainable drag reduction and developing a biomimetic sustainable drag-reducing surface.1

  • Effects of surface morphological structure of a brown alga miyeok (Undaria pinnatifida) on sustainable drag reduction
    'AIP Publishing', 2020
    Co-Authors: Lee, Sang Joon, Heo Seongkwang, Yoon, Gun Young, Seo Eunseok, Choi Woorak
    Abstract:

    Liquid-infused surfaces are a promising Passive Technique for frictional drag reduction. However, their practical application is limited by the easy depletion of the lubricant infused in the surface by external forces. Miyeok contains mucus on its surface, which induces a sustainable slippery surface under flow conditions. In this study, the effect of the surface morphological structures of miyeok on slippery characteristics was examined. The surface of miyeok has bump-like microstructures and tiny pores of mucilage gland cells with a re-entrant inlet configuration. A replica model of the miyeok surface was fabricated by adopting a molding process using polydimethylsiloxane. The miyeok replica model was dipped into a silicone oil solution to obtain a slippery surface property. The surface structures of fresh miyeok and the replica were checked by comparing their scanning electron microscopy images. A replica of a kelp surface was also fabricated by employing the same method. The heights of the surface microstructures of the miyeok replica were more uniform than those of the kelp replica. The sustainable drag reduction effect of the replica models' surfaces was assessed by a sessile drop method. The liquid-infused miyeok replica surface (LIMRS) showed better sustainability than other surfaces. The slippery properties of the LIMRS were examined by measuring slip length and pressure drop. The drag reduction rates measured by the two methods were approximately 24% and 19%. The present results would be helpful for understanding the effects of the surface structure of natural miyeok on sustainable drag reduction and developing a biomimetic sustainable drag-reducing surface.11Ysciescopu

Yetao Xiang - One of the best experts on this subject based on the ideXlab platform.

  • experimental investigation of a photovoltaic thermal collector with energy storage for power generation building heating and natural ventilation
    Renewable Energy, 2020
    Co-Authors: Guohui Gan, Yetao Xiang
    Abstract:

    Abstract A phase change material (PCM) can be used for thermal management of photovoltaics and thermal energy storage. This paper presents a photovoltaic thermal (PVT) system integrated with a PCM as a thermal storage medium for managing the photovoltaic temperature and together with a ventilation duct for preheating supply air or natural ventilation of a building. The novelty of the integrated PVT/PCM system lies in using the PCM as a Passive Technique not only for PV cooling but also for building heating and ventilation. Experiments have been carried out on a prototype PVT system for different sizes of PCM. The results show that a 30 mm thick PCM layer with a phase change temperature of 25 °C can maintain the PV temperature below 45 °C and improve the PV electrical efficiency by 10% for about 210 min under 600 W/m2 insolation. Increasing the PCM thickness by 10 mm increases the time for thermal control by 60–70 min. The PVT/PCM system is able to generate a 15 L/s ventilation rate in a vertical duct of 1100 mm wide, 1200 mm high and 100 mm deep during the melting phase and at least 20 L/s during the solidification phase. Use of metal fins to enhance heat transfer in the PCM can increase the PV electrical efficiency further by 3% and the ventilation rate by 30%.