Browsing by Author "Lin, YY"

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Compact efficient passively Q-switched Nd : GdVO4/PPLN/Cr4+: YAG tunable intracavity optical parametric oscillator
(2005-11-14)
Tsai, LY
;
Chen, YF
;
Lin, ST
;
Lin, YY
;
Huang, YC
We report on a compact efficient diode pumped passively Q-switched Nd:GdVO4/ Cr4+:YAG/ PPLN intracavity optical parametric oscillator (OPO) with a shared-resonator configuration. Experimental results reveal that the amplitude stability of the shared-resonator configuration is substantially superior to that of the conventional coupled-resonator configuration. At a diode pump power of 15 W, the compact intracavity OPO cavity produces the average power greater than 900 mW with a pulse repetition rate of 36 kHz. The output pulses noticeably display the mode-locking phenomenon that leads to the maximum peak power to be higher than 20 kW. (c) 2005 Optical Society of America.
Control of H2S waste gas emissions with a biological activated carbon filter
(2004-06-01)
Chung, YC
;
Lin, YY
;
Tseng, CP
;
生物科技學系
;
Department of Biological Science and Technology
The removal of high concentrations of H2S from waste gases containing mixtures of H2S and NH3 was studied using the pilot-scale biofilter. Granular activated carbon (GAC), selected as support material in this study, demonstrated its high adsorption capacity for H2S and good gas distribution. Extensive tests to determine removal characteristics, removal efficiency, and removal capacity of high H2S levels and coexisting NH3 in the system were performed. In seeking the appropriate operating conditions, the response surface methodology (RSM) was employed. H2S removal capacities were evaluated by the inoculated bacteria (biological conversion) and BDST (Bed Depth Service Time) methods (physical adsorption). An average 98% removal efficiency for 0.083-0.167 mg dm(-3) of H2S and 0.004-0.021 mg dm(-3) of NH3 gases was achieved during the operational period because of rapid physical adsorption by GAC and subsequently an effective biological regeneration of GAC by inoculated Pseudomonas putida CH11 and Arthrobacter oxydans CH8. The results showed that H2S removal efficiency for the system was not affected by inlet NH3 concentrations. In addition, no acidification was observed in the BAC biofilter. High buffer capacity and low moisture demand were also advantages of this system. The maximal inlet loading and critical loading for the system were 18.9 and 7.7 g-H2S m(-3) h(-1), respectively. The results of this study could be used as a guide for the further design and operation of industrial-scale systems. (C) 2004 Society of Chemical Industry.
Experimental characterization of the vibrational behavior of a fluid-filled thin shell for the purpose of response estimation
(1995-12-01)
Bai, MR
;
Lin, YY
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
Experimental techniques are proposed for developing a model to estimate structural vibrations induced by internal acoustic pressure at low frequencies. In these methods, the acoustic field and the structure are treated as a coupled system with the acoustic loading effect taken into account. The response model between the internal pressure and the surface vibration is established by a modified modal test on the coupled system. Experiments are performed to investigate the surface vibrations of a closed steel cylindrical shell excited by a loudspeaker inside. The experimental results show that developed techniques provide accurate estimation for the acoustically induced vibrations. (C) 1995 Acoustical Society of America.
Intracavity PPLN crystals for ultra-low-voltage laser Q-switching and high-efficiency wavelength conversion
(2005-06-01)
Chen, YH
;
Huang, YC
;
Lin, YY
;
Chen, YE
;
電子物理學系
We report to the best of our knowledge the lowest switching voltage in an electro-optically Q-switched Nd: YVO4 laser by using a 13-mm long, 14-μ m-period PPLN crystal as a Pockels cell. A switching voltage as low as &SIM; 50V in the PPLN crystal was sufficient to hold off the lasing of the Q-switched laser at a pump power more than two times above its continuous-wave threshold. When the PPLN Q-switch was driven by a 100-V voltage at 6.5 kHz, we obtained 0.9-kW laser peak power from this 1-W diode-pumped Nd: YVO4 laser system with 13% output coupling. When the PPLN Pockels cell was cascaded with a 5-cm long, 30-μ m-period PPLN crystal, we produced &SIM; μ J/pulse energy at 1.59 μ m from optical parametric generation inside the actively Q-switched laser.
Operational characteristics of effective removal of H2S and NH3 waste gases by activated carbon biofilter
(2004-04-01)
Chung, YC
;
Lin, YY
;
Tseng, CP
;
生物科技學系
;
Department of Biological Science and Technology
Simultaneous removal of hydrogen sulfide (H,S) and ammonia (NH3) gases from gaseous streams was studied in a biofilter packed with granule activated carbon. Extensive studies, including the effects of carbon (C) source on the growth of inoculated microorganisms and gas removal efficiency, product analysis, bioaerosol emission, pressure drop, and cost evaluation, were conducted. The results indicated that molasses was a potential C source for inoculated cell growth that resulted in removal efficiencies of 99.5% for H2S and 99.2% for NH3. Microbial community observation by scanning electron microscopy indicated that granule activated carbon was an excellent support for microorganism attachment for long-term waste gas treatment. No disintegration or breakdown of biofilm was found when the system was operated for 140 days. The low bioaerosol concentration emitted from the biofilter showed that the system effectively avoided the environmental risk of bioaerosol emission. Also, the system is suitable to apply in the field because of its low pressure drop and treatment cost. Because NH3 gas was mainly converted to organic nitrogen, and H2S gas was converted to elemental sulfur, no acidification or alkalinity phenomena were found because of the metabolite products. Thus, the results of this study demonstrate that the biofilter is a feasible bioreactor in the removal of waste gases.
Pulsed optical parametric generation, amplification, and oscillation in monolithic periodically poled lithium niobate crystals
(2004-06-01)
Chiang, AC
;
Wang, TD
;
Lin, YY
;
Lau, CW
;
Chen, YH
We conducted a series of passively Q-switched Nd:YAG laser pumped optical parametric generation, amplification, and oscillation experiments in monolithic periodically poled lithium niobate (PPLN) crystals. Double-pass optical parametric generation with an effective gain length of 10 cm in a PPLN crystal was performed in comparison with single-pass operation in the same crystal. By seeding a PPLN, optical parametric amplifier with a distributed feedback (DFB) diode laser, we produced 200-ps transform-limited laser pulses at 1549.6 mn and observed parametric gain competition at different pump levels. For optical parametric oscillations, we first demonstrated 22% power efficiency from a 2.4-cm intrinsic-cavity PPLN optical parametric oscillator pumped by a 4.2-ns, 10-kW passively Q-switched Nd:YAG laser. Preliminary studies on DFB optical parametric oscillators in PPLN are mentioned. The temporal and spectral properties of these optical parametric generators, amplifiers, and oscillators are characterized and discussed.
Removal of high concentration of NH3 and coexistent H2S by biological activated carbon (BAC) biotrickling filter
(2005-11-01)
Chung, YC
;
Lin, YY
;
Tseng, CP
;
生物科技學系
;
Department of Biological Science and Technology
High efficiency of NH3 and H2S removal from waste gases was achieved by the biotrickling filter. Granular activated carbon (GAC), inoculated with Arthrobacter oxydans CH8 for NH3 removal and Pseudomonas putida CH11 for H2S removal, was used as packing material. Under conditions in which 100% H2S was removed, extensive tests to eliminate high concentrations of NH3 emission-including removal characteristics, removal efficiency, and removal capacity of the system-were performed. The results of the Bed Depth Service Time (BDST) experiment suggested that physical adsorption of NH3 gas by GAC was responsible for the first 10 days, after which NH3 gas was biodegraded by inoculated microorganisms. The dynamic steady state between physical adsorption and biodegradation was about two weeks. After the system achieved equilibrium, the BAC biotrickling filter exhibited high adaptation to shock loading, elevated temperature, and flow rate. Greater than 96% removal efficiency for NH3 was achieved during the 140-day operating period when inlet H2S loading was maintained at 6.25 g-S/m(3)/h. During the operating period, the pH varied between 6.5 and 8.0 after the physical adsorption stage, and no acidification or alkalinity was observed. The results also demonstrated that NH3 removal was not affected by the coexistence of H2S while gas retention time was the key factor in system performance. The retention time of at least 65 s is required to obtain a greater than 95% NH3 removal efficiency. The critical loading of NH3 for the system was 4.2 g-N/m(3)/h, and the maximal loading was 16.2 g-N/m(3)/h. The results of this study could be used as a guide for further design and operation of industrial-scale systems. (c) 2005 Elsevier Ltd. All rights reserved.
Simultaneous amplitude modulation and wavelength conversion in an asymmetric-duty-cycle periodically poled lithium niobate
(2003-08-01)
Chen, YH
;
Fan, FC
;
Lin, YY
;
Huang, YC
;
Shy, JT
We report the theory and experiment for an amplitude modulator and wavelength converter based on an electrode-coated asymmetric-duty-cycle periodically poled lithium niobate (PPLN). In a 56%/44% domain-duty-cycle PPLN crystal, we modulated the amplitude of the 532-nm second-harmonic output and measured a normalized half-wave voltage of 1.1 V x d (mum)/I-eff (cm), where d is the separation of the electrodes and I-cff is the effective electrode length defined by the PPLN length multiplying the deviation of the domain-duty-cycle from the 50% value. A modulation depth of 85% was obtained in the linear modulation regime. We also derived a unified theory to describe the half-wave voltage for two types of PPLN-based amplitude modulators. (C) 2003 Elsevier Science B.V. All rights reserved.
Single-longitudinal-mode, tunable dual-wavelength, CWNd : YVO4 laser
(2006-06-12)
Lin, YY
;
Chen, SY
;
Chiang, AC
;
Tu, RY
;
Huang, YC
We report a single-longitudinal-mode CW diode-pumped Nd:YVO4 laser emitting at both 1064 and 1342 nm with 10% optical efficiency at 20-W pump power. The measured spectral widths at 1064 and 1342 nm were less than 450 MHz and 400 MHz, respectively. The two emission wavelengths can be independently tuned over the lasing bandwidths of the dual-wavelength laser. (c) 2006 Optical Society of America.
Transport through a quantum ring, dot, and barrier embedded in a nanowire in magnetic field
(2005-06-01)
Gudmundsson, V
;
Lin, YY
;
Tang, CS
;
Moldoveanu, V
;
Bardarson, JH
We investigate the transport through a quantum ring, a dot, and a barrier embedded in a nanowire in a homogeneous perpendicular magnetic field. To be able to treat scattering potentials of finite extent in a magnetic field we use a mixed momentum-coordinate representation to obtain an integral equation for the multiband scattering matrix. For a large embedded quantum ring we are able to obtain Aharonov-Bohm type of oscillations with superimposed narrow resonances caused by interaction with quasibound states in the ring. We also employ the scattering matrix approach to calculate the conductance through a semiextended barrier or well in the wire. The numerical implementations we resort to in order to describe the cases of weak and intermediate magnetic field allow us to produce high resolution maps of the "near field" scattering wave functions, which are used to shed light on the underlying scattering processes.