Great interest has been generated in the use of natural fibres as environmentally friendly reinforcing materials in polymeric composites, which do not require high load bearing capabilities. kenaf fibres extracted from kenaf plants (hibiscus cannabinus) have been identified as an attractive option due to its production cost and the ability of the kenaf plants to grow in a variety of climatic conditions. Polypropylene (PP) has a relatively low production cost, excellent corrosion resistance, good retention of mechanical properties and less recycling challenges in comparison to other matrix systems such as thermosets. Given the individual advantages of kenaf fibre and polypropylene, kenaf reinforced polypropylene composites (kenaf/PP composites) have considerable commercial interest in the composite industry. However, limitations arise with respect to the mechanical performance and to the resistance to moisture absorption when natural fibres are used. This study focuses on the improvement of the mechanical properties (e.g. tensile, flexural, fatigue and impact properties) and the resistance to moisture absorption of kenaf reinforced polypropylene composites by means of fibre treatments (e.g. alkali and alkali-silane treatments) and the use of filler materials (e.g. functionalized multi-wall carbon nanotubes). Kenaf reinforced polypropylene composites are manufactured by a modified compression moulding using the film–stacking technique. The crux of this technique is that kenaf mats are impregnated with polypropylene powder in order achieve a uniform material distribution and to lower the manufacturing temperature, thereby preventing the thermal alteration of the composite constituents (e.g. kenaf fibres) and silano functional groups attached to the multi-wall carbon nanotubes. Fibre treatments including alkali treatments and alkali followed by silane treatments (alkali-silane) are considered in order to improve the fibre-matrix interfacial adhesion. The concentrations of the alkali solutions range from 1% to 8% in intervals of 1% by mass. Fibre contents ranging from 20% to 35% in interval of 5% by mass are considered for both kenaf and glass fibre reinforced plates. Functionalized multi-wall carbon nanotubes are used as filler material in order to improve the mechanical properties of the composite plates. The concentrations of the multiwall carbon nanotube (MWCNT) range from 0.1% to 1.25%. Mechanical test and microscopic examination results showed that alkali treatments improve the mechanical properties of kenaf/PP composites. However, the improvements due to alkali-silane treatments were found to be more significant because additional silane treatments substantially enhanced the fibrematrix interfacial adhesion. Material failures in untreated kenaf/PP composites and alkali treated kenaf/PP composites were mainly characterized by fibre pullouts, whereas in alkali-silane treated kenaf/PP composites they were characterised by fibre breakage. Alkali concentrations of 5% and 6% NaOH are found to the optimum concentrations for both alkali treatment and alkali-silane treatment. The use of functionalized MWCNTs as filler material improved furthermore the mechanical properties of kenaf/PP-MWCNT composites in comparison to those of kenaf/PP and glass/PP composites. The main contributing factors of the improvements were found to be the enhancement of the interfacial adhesion between the nanoparticles and the matrix, and also between the nanoparticles and kenaf fibres. Material failures in kenaf/PP-MWCNT composites were characterized by fibre breakage and matrix cracks. The optimum MWCNT concentrations were found to be 0.5% and 0.75%. 30% fibre contents was found to be the optimum fibre content for both kenaf/PP and kenaf/PP-MWCNT composites. Test results showed that the fibre treatments, especially alkali-silane treatment, improved the resistance to moisture absorption of the composites. Test results also showed that the manufacturing technique, which enables the manufacturing of composite plates with layers of different moisture diffusion resistances, has a significant influence on the resistance of kenaf/PP composites. The addition of multi-wall carbon nanotubes to the polypropylene matrix did not alter the moisture absorption resistance of kenaf/PP-MWCNT composites. The impregnation of kenaf and fibre glass mats with polypropylene powder significantly lowered the manufacturing temperature

Optical amplification and signal processing are of great importance to ensure reliable operation of fiber-optic networks. The capacity of optical networks are growing rapidly to deal with the ever-growing Internet traffic demand, which requires optical amplification and signal processing to have ultra-fast response, wide operation bandwidth, flexible operation spectral range and transparency to different modulation formats. In this regard, fiber optical parametric amplifiers (FOPAs), which rely on the efficient parametric process in highly nonlinear fibers, are promising to operate as amplifiers and signal processers in future high-capacity optical networks. This thesis focuses on the advanced schemes of optical amplification and signal processing based on FOPAs to cope with the developing optical networks. / New optical amplifiers are highly desirable for previously unused optical bands to increase aggregate optical communication bandwidth. Raman-assisted FOPAs are promising because they can provide higher gain efficiency than Raman amplifiers and more flexible operation spectral range than the conventional FOPAs. Gain saturation is an important property of parametric amplification, which may result in signal distortion during amplification but can be utilized for optical regeneration. In this thesis, gain saturation characteristics in a Raman-assisted FOPA are experimentally observed and theoretically analyzed through simulations. As compared to a conventional FOPA, gain saturation is deferred with enhanced saturated output power and the saturated gain spectrum is broadened with suppressed signal wavelength dependence in the Raman-assisted FOPA. The novel saturation behaviors are explained by the modification of the parametric pump power and nonlinear phase mismatch by the backward Raman amplification. Moreover, controlling saturation behaviors by tuning the Raman gain on the parametric pump are demonstrated. / Amplification performance of Raman-assisted FOPAs is further investigated, including single-channel amplification incorporating with coherent reception and multi-channel amplification for wavelength division multiplexing (WDM) systems. In the single-channel amplification, sufficient amplification performance for the QPSK signal has been successfully achieved in two Raman-assisted FOPAs with the same signal gain of 19 dB but different pump power combinations. In addition, the FOPA with a higher Raman pump is more advantageous due to the wider gain bandwidth and the deferred signal gain saturation. Nonlinear crosstalk is the major restriction of FOPAs for multi-channel amplification in WDM systems. We propose and demonstrate suppression of cross-gain modulation (XGM) crosstalk and four-wave mixing (FWM) crosstalk using a Raman-assisted FOPA. The performances are compared between FOPAs with and without the Raman pump under the condition of identical unsaturated gains. The reduction of XGM crosstalk utilizes the deferred gain saturation in the Raman-assisted FOPA which implies a larger range of input signal power for a constant gain. On the other hand, the suppression of FWM crosstalk is based on the unique signal power evolution which has a crescent slope along the fiber. Accordingly, the performance of multi-channel amplification has been improved in the Raman-assisted FOPA. / Polarization division multiplexing (PDM) in combination with phase-shift keying (PSK) signals is being increasingly employed to improve the spectral efficiency of optical networks. Gain-saturated FOPA is an attractive approach to reduce the nonlinear phase noise and improve the transmission performance by suppressing the amplitude noise of PSK signals. In this thesis, saturation characteristics of FOPA are investigated in terms of input signal polarizations. Our theoretical analysis and experimental results show that PDM signals exhibit nearly identical saturation behaviors when two orthogonal polarized pumps are applied. In addition, polarization-insensitive gain saturation can be achieved by optimizing the pump powers. We report the experimental demonstration on polarization-insensitive amplitude regeneration of 40-Gb/s DPSK signals and amplitude regeneration of 80-Gb/s PDM RZ-DPSK signals. / 光信號的放大和處理在確保光纖通信網絡的可靠運行中起著至關重要的作用。隨著因特網流量需求的不斷增長，光網絡的容量也在高速增長，這就要求光信號的放大和處理具有超快的響應速度，更大的工作帶寬，靈活可調的光譜範圍以及對不同調制格式的透明度。光纖參量放大器是一種基於高非線性光纖的高效率參量過程的多功能器件，非常適合用於未來高容量光網絡中的光信號放大和處理。本論文將致力於研究基於光纖參量放大器的先進技術以適用於快速發展的光通信網絡中光信號的放大和處理。 / 為了拓展總的光通信帶寬，適用於新的光學波段的新型光放大器是非常重要的。拉曼輔助光纖參量放大器具有高於拉曼放大器的增益效率，與傳統的光纖參量放大器相比更加靈活的工作光譜範圍，是一種優秀的新型光放大器。增益飽和是參量放大過程的一種重要特性，它既可能引進放大過程中的信號損傷，又可用於全光再生。本文通過實驗觀察和理論模擬研究了拉曼輔助光纖參量放大器的增益飽和特性。與傳統的光纖參量放大器相比，拉曼輔助光纖參量放大器需要更高的信號輸入功率以達到增益飽和，具有增強的飽和輸出功率。飽和條件下其增益光譜被展寬，而飽和特性與信號波長的相關性被減弱。通過模擬計算，我們得出這些新穎的飽和特性的物理解釋：反向的拉曼放大過程改變了參量泵浦功率和非線性相位失配在光纖中的分布。另外，通過調節參量泵浦的拉曼增益，我們還展示信號增益飽和特性的控制。 / 我們進一步研究了拉曼輔助光纖參量放大器在信號放大方面的性能，包括了單通道信號的放大和波分復用系統中多通道信號的放大。在單通道信號放大的研究中，我們研究了兩種具有不同泵浦功率組合的放大器，而這兩種放大器都提供19dB的增益。實驗中，我們采用相幹接收對放大後的四相相移鍵控信號進行分析，發現兩種放大器都具有令人滿意的放大效果。同時我們還發現其中具有高的拉曼泵浦功率的放大器更有優勢，因為它能夠提供更大的增益帶寬和更加延遲的信號增益飽和。非線性串擾是光纖參量放大器應用於波分復用系統中多波長信號放大的主要障礙。我們提出拉曼輔助光纖參量放大器可用於抑制多通道信號放大時的交叉增益調制串擾和四波混頻串擾。在我們的研究中，拉曼輔助光纖參量放大器在多通道放大方面的優越性能是通過與具有相同線性增益的傳統光纖參量放大器進行比較體現出來的。拉曼輔助光纖參量放大器的延遲增益飽和說明了在更大的信號輸入光功率範圍內不會引起參量泵浦的明顯減弱，因而可以用於抑制交叉增益調制串擾。另一方面，拉曼輔助光纖參量放大器使信號在光纖中具有獨特的功率演變過程，可用於降低四波混頻串擾。因此，我們利用拉曼輔助光纖參量放大器成功地提高了多通道放大的信號質量。 / 偏振復用技術與相移鍵控調制格式的結合越來越多地被用於提高光網絡的頻譜效率。光纖參量放大器的增益飽和是一種很有吸引力的抑制相移鍵控信號幅度噪聲的方法，可以有效地降低非線性相位噪聲從而提高傳輸性能。本文研究了不同信號偏振情況下光纖參量放大器的增益飽和特性。理論分析和實驗結果都顯示在采用正交偏振的參量泵浦時偏振復用信號具有相同的增益飽和特性。另外，偏振不敏感的增益飽和可以通過調節泵浦功率實現。我們成功展示了40-Gb/s非歸零差分相移鍵控信號的偏振不敏感幅度再生以及80-Gb/s偏振復用歸零差分相移鍵控信號的幅度再生。 / Guo, Xiaojie. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references. / Abstracts also in Chinese. / Title from PDF title page (viewed on 12, September, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

by Chun-kit Chan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 68-[73]). / Chapter 1 --- A High-Speed All-Optical Tunable-Channel Multi-Access (TCMA) Network --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Tunable-Channel Multi-Access (TCMA) Networks --- p.4 / Chapter 1.3 --- Protocols For TCMA Networks --- p.5 / Chapter 1.3.1 --- Media Access Procedure For ACTA Protocol --- p.6 / Chapter 1.3.2 --- Cyclc Utilization & Adaptive Algorithm --- p.8 / Chapter 1.3.3 --- Advantages of ACTA Protocol --- p.9 / Chapter 1.4 --- Proposed High-Speed Photonic TDM Implementation --- p.10 / Chapter 1.4.1 --- Centralized Pulse Source --- p.12 / Chapter 1.4.2 --- Channel-Tunable Transmitter --- p.14 / Chapter 1.4.3 --- High Speed All-Optical Demultiplexing --- p.22 / Chapter 1.4.4 --- Timing and Synchronization --- p.23 / Chapter 1.4.5 --- Advantages of the Proposed Scheme --- p.24 / Chapter 1.5 --- Other Network Issues --- p.25 / Chapter 1.5.1 --- Scalability --- p.25 / Chapter 1.5.2 --- Surviability --- p.26 / Chapter 1.5.3 --- Cost-Effectiveness --- p.27 / Chapter 1.6 --- Conclusion --- p.28 / Chapter 2 --- Theoretical Analysis of High Repetition Rate Optical Pulse Multiplication using Fiber Coupler Loop Configuration --- p.29 / Chapter 2.1 --- Introduction --- p.29 / Chapter 2.2 --- Single Coupler Loop Configuration --- p.30 / Chapter 2.3 --- Cascaded Coupler Loop Configuration --- p.34 / Chapter 2.4 --- Discussion --- p.36 / Chapter 2.5 --- Conclusion --- p.38 / Chapter 3 --- Spectrum Analysis of Multichannel CATV Systems --- p.39 / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Considerations of Analysis of Multichannel CATV Systems --- p.41 / Chapter 3.3 --- Effects of Incomplete-cycle Sampling --- p.43 / Chapter 3.4 --- Methods to Alleviate the Incomplete-cycle Sampling Effcct --- p.48 / Chapter 3.4.1 --- Windowing --- p.48 / Chapter 3.4.2 --- Correction --- p.54 / Chapter 3.5 --- Nonlinear Distortion in Multichannel CATV Systems --- p.55 / Chapter 3.5.1 --- Two-tone Third Order Distortion Estimation --- p.56 / Chapter 3.5.2 --- Composite Triple Beat Estimation --- p.62 / Chapter 3.6 --- A Procedure of Spectrum Analysis for Multichannel CATV Systems --- p.64 / Chapter 3.7 --- Conclusion --- p.67 / Bibliography --- p.68 / Chapter A --- Implementation of a high-speed TCMA optical network --- p.74 / Chapter A.1 --- System Setup --- p.74 / Chapter A.2 --- Channel-tunable Delay Line Circuit --- p.75 / Chapter A.3 --- DFB Laser diode --- p.76 / Chapter A.4 --- Erbium-doped Fiber Amplifier (EDFA) --- p.76 / Chapter A.5 --- 1 Gb/s to 16 Gb/s Fiber Multiplexer --- p.77 / Chapter A.6 --- Nonlinear Amplifying Loop Mirror (NALM) --- p.77 / Chapter A.7 --- Decision Circuit --- p.78 / Chapter B --- Frequency Assignment Scheme of CATV Systems --- p.79 / Chapter C --- Derivation --- p.80 / Chapter C.1 --- Channel Carrier Power Level Variation with Rectangular Window --- p.81 / Chapter C.2 --- Channel Carrier Power Level With Hanning Window Function ´Ø --- p.82 / Chapter C.3 --- Correction Factor for the Channel Carriers --- p.83 / Chapter C.4 --- Correction Scheme for Distortion Terms --- p.83

by Poon Wing-chak. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Includes bibliographies.

by Yeung, Sai-mo, Simon. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 189-207.

Hui Yuen Yung. / Thesis submitted in: August 1998. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 70-73). / Text in English; abstract also in Chinese. / Hui Yuen Yung. / Acknowledgements --- p.vi / Abstract --- p.vii / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Second harmonic generation --- p.5 / Chapter 2.1 --- Introduction --- p.5 / Chapter 2.2 --- Maxwell's equations in dielectric media --- p.6 / Chapter 2.3 --- Second harmonic generation --- p.7 / Chapter 2.4 --- Phase matching --- p.8 / Chapter 2.5 --- Quasi phase matching --- p.10 / Chapter 2.6 --- Inversion symmetry --- p.11 / Chapter 3 --- Third order nonlinear optical processes in optical fibers --- p.14 / Chapter 3.1 --- Introduction --- p.14 / Chapter 3.2 --- Optical fibers --- p.15 / Chapter 3.3 --- Third order interaction between waves of same frequency --- p.16 / Chapter 3.4 --- Third order interaction between waves of different frequencies --- p.19 / Chapter 4 --- Multiphoton ionization interference effect --- p.23 / Chapter 4.1 --- Historical development --- p.23 / Chapter 4.2 --- Multiphoton ionization interference effect --- p.26 / Chapter 4.3 --- Periodic ionization --- p.27 / Chapter 4.4 --- Periodic electric field --- p.28 / Chapter 4.5 --- Physical interpretation --- p.29 / Chapter 5 --- Experimental setup --- p.32 / Chapter 5.1 --- Introduction --- p.32 / Chapter 5.2 --- Laser system --- p.32 / Chapter 5.3 --- Optical fibers --- p.33 / Chapter 5.4 --- Coupling light into fibers --- p.34 / Chapter 5.5 --- Detection system --- p.36 / Chapter 5.6 --- Optical layout --- p.36 / Chapter 6 --- Second harmonic generation in optical fibers --- p.40 / Chapter 6.1 --- Introduction --- p.40 / Chapter 6.2 --- Self-preparation in optical fibers --- p.41 / Chapter 6.3 --- Polarization dependence --- p.42 / Chapter 6.4 --- Seeding optical fibers --- p.42 / Chapter 6.5 --- Seeding by varying green light intensity --- p.45 / Chapter 6.6 --- Square dependence of second harmonic generation in optical fibers --- p.46 / Chapter 7 --- Erasure of x(2) grating in optical fibers --- p.56 / Chapter 7.1 --- Introduction --- p.56 / Chapter 7.2 --- Experiment --- p.58 / Chapter 7.3 --- Results --- p.59 / Chapter 7.3.1 --- Erasure by different propagating mode --- p.59 / Chapter 7.3.2 --- Erasure in germanium-doped fiber --- p.60 / Chapter 7.3.3 --- Erasure in erbium-doped fiber --- p.61 / Chapter 7.4 --- Discussion --- p.61 / Chapter 8 --- Conclusion --- p.68 / Chapter 8.1 --- Summary of our work --- p.68 / Chapter 8.2 --- Outlook --- p.69 / Chapter 8.2.1 --- Multiphoton ionization in polymer --- p.69 / Chapter 8.2.2 --- Erasure by blue light --- p.69 / Bibliography --- p.70

No description available.

Chow Kin Kee. / May, 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Both gain transient and dynamic gain control devices were also designed and fabricated as photonic integrated circuits (PICs). Silicon-based PICs were able to perform dynamic gain tilt compensation by thermo-optic effect. Helium doped SOI rib waveguides were used for power monitoring and is potentially used as monolithic gain tilt compensation device with arrayed waveguide grating (AWG). / Dynamic gain tilt induced by wavelength dependent gain of EDFA leads to power penalty in wavelength division multiplexed systems. Using optical filter with known spectral response, it is possible to detect dynamic gain tilt and a per-band compensation scheme using electronic variable optical attenuators. This was implemented for dynamic gain tilt compensation (DGTC). / Dynamic provisioning of bandwidth and re-configurable optical networks can potentially allow efficient and cost effective deliveries of services based on the actual bandwidth requirement. Optical add/drop multiplexers (OADM) and optical cross-connects (OXC) will be used for such networks but the dynamic provisioning of optical channels may introduce optical power transients because of the slow gain dynamics of erbium doped fiber amplifiers. In this dissertation, the potential problems on using Erbium Doped Fiber Amplifiers (EDFA) in future reconfigurable optical networks are studied and possible solutions are assessed. In particular, the problems of gain transient and dynamic gain tilt were studied experimentally and theoretically. / In saturated EDFA channel add/drop can produce average power fluctuations, in timescales in the microsecond range. The thesis describes how gain transients can be minimized in gain clamped EDFA by optimizing erbium concentrations of EDF. Both simulations and experiments demonstrate that highly doped EDF minimize the transient in gain clamped EDFA. For unclamped EDFA, all-optical feedforward constant output power compensation has been successfully demonstrated using electronic variable optical attenuator (EVOA). / Chan Po Shan. / "August 2006." / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1813. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Book SummaryL Appalachia holds a curious place in the American psyche. There is a pervasive perception of the region as a hinterland inhabited by a backward and developmentally stunted people. Economically, culturally, and technologically suspended in an era gone by, this Appalachia is regarded as one of America's enduring social and economic problems.But there is another perception of Appalachia-home to the beautiful mountain system for which the region is named. It is a quaint retreat into the past, reflecting the integrity of a people with a pioneering spirit and lifestyle that pays homage to a simpler time.Until now, there has been no general reference work that captures the complexities of this enigmatic region. The only guide of its kind, the Encyclopedia of Appalachia is replete with information on every aspect of Appalachia's history, land, culture, and people.Containing more than 2,000 entries in 30 sections, the Encyclopedia is designed for quick reference and access to the information you need to know. Teachers, students, scholars, historians, and browsers with a passing interest in this beautiful and richly distinct region will quickly come to rely on the Encyclopedia of Appalachia as the authoritative resource on Appalachia's past and present.The Encyclopedia details subjects traditionally associated with Appalachia-folklore, handcrafts, mountain music, foods, and coal mining-but goes far beyond regional stereotypes to treat such wide-ranging topics as the aerospace industry, Native American foodways, ethnic diversity in the coalfields, education reform, linguistic variation, and the contested notion of what it means to be Appalachian, both inside and outside the region.Researched and developed by the Center for Appalachian Studies and Services at East Tennessee State University, this 1,840-page compendium includes all thirteen states that constitute the northern, central, and southern subregions of Appalachia-from New York to Mississippi. With thorough, detailed, yet accessible entries on everything from Adventists to zinc mining, the Encyclopedia of Appalachia is an indispensable, one-stop guide to all things Appalachian.