Browsing by Author "Lin, Wei-Chih"

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A polarization-independent liquid crystal phase modulation using polymer-network liquid crystal with orthogonal alignment layers
(2012-01-01)
Chen, Ming-Syuan
;
Lin, Wei-Chih
;
Tsou, Yu-Shih
;
Lin, Yi-Hsin
;
光電工程學系
A polarization-independent liquid crystal (LC) phase modulation using polymer-network liquid crystals with orthogonal alignments layers (T-PNLC) is demonstrated. T-PNLC consists of three layers. LC directors in the two layers near glass substrates are orthogonal to each other. In the middle layer, LC directors are perpendicular to the glass substrate. The advantages of such T-PNLC include polarizer-free, larger phase shift (similar to 0.4 pi rad) than the residual phase type (< 0.05 pi rad), and low operating voltage (< 30V(rms)). It does not require bias voltage for avoiding scattering because the refractive index of liquid crystals matches that of polymers. The phase shift of T-PNLC is affected by the cell gap and the curing voltages. The potential applications are laser beam steering, spatial light modulators and electrically tunable micro-lens arrays.
A polarization-independent liquid crystal phase modulation using polymer-network liquid crystal with orthogonal alignment layers
(2012-01-01)
Chen, Ming-Syuan
;
Lin, Wei-Chih
;
Tsou, Yu-Shih
;
Lin, Yi-Hsin
;
光電工程學系
A polarization-independent liquid crystal (LC) phase modulation using polymer-network liquid crystals with orthogonal alignments layers (T-PNLC) is demonstrated. T-PNLC consists of three layers. LC directors in the two layers near glass substrates are orthogonal to each other. In the middle layer, LC directors are perpendicular to the glass substrate. The advantages of such T-PNLC include polarizer-free, larger phase shift (similar to 0.4 pi rad) than the residual phase type (< 0.05 pi rad), and low operating voltage (< 30V(rms)). It does not require bias voltage for avoiding scattering because the refractive index of liquid crystals matches that of polymers. The phase shift of T-PNLC is affected by the cell gap and the curing voltages. The potential applications are laser beam steering, spatial light modulators and electrically tunable micro-lens arrays.
A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degrees twisted cell
(2012-07-15)
Lin, Yi-Hsin
;
Chen, Ming-Syuan
;
Lin, Wei-Chih
;
Tsou, Yu-Shih
;
光電工程學系
A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degrees twisted cell (T-PNLC) is demonstrated. T-PNLC consists of three layers. Liquid crystal (LC) directors in the two layers near glass substrates are orthogonal to each other and those two layers modulate two eigen-polarizations of an incident light. As a result, two eigen-polarizations of an incident light experience the same phase shift. In the middle layer, LC directors are perpendicular to the glass substrate and contribute no phase shift. The phase shift of T-PNLC is electrically tunable and polarization-independent. T-PNLC does not require any bias voltage for operation. The phase shift is 0.28 pi rad for the voltage of 30 V-rms. By measuring and analyzing the optical phase shift of T-PNLC at the oblique incidence of transverse magnetic wave, the pretilt angle of LC directors and the effective thickness of three layers are obtained and discussed. The potential applications are spatial light modulators, laser beam steering, and micro-lens arrays. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737260]
Analysis of microbial diversity and optimal conditions for enhanced biogas production from swine waste anaerobic digestion
(2013-09-01)
Chung, Ying-Chien
;
Chang, Yu-Cheng
;
Chen, Yu-Pei
;
Lin, Wei-Chih
;
Lin, Hsiao-Hsien
Swine wastewater pretreated by solid-liquid separation was optimized for biogas production and water purification. Dynamic diversity of the bacterial community in the anaerobic plug flow reactor was investigated under various temperatures and hydraulic retention times (HRT). Results of batch experiments indicated that under optimal operating conditions, biogas production, methane production rate, and chemical oxygen demand (COD) removal efficiencies increased up to 26%, 52%, and 44%, respectively. In the continuous experiments, optimal operating conditions for the plug flow operator were found to be HRT of 8 d and temperature of 35 degrees C, under which relatively high CH4 concentration (67%), CH4 production rate (4.6 l/d), and total COD removal (79%) were achieved. A minimum of 12 bands was observed in the denaturing gradient gel electrophoresis profile. Phylogenetic analysis revealed the predominance of phyla Firmicutes, Proteobacteria, and Euryarchaeota in the anaerobic plug-flow reactor. However, the occurrence and prevalence of specific bacterial species varied with HRT and temperature. This study establishes the optimal operating parameters for the anaerobic plug-flow digestion of swine wastewater, which can be employed in a full-scale reactor to maximize biogas production and to purify water quality. (C) 2013 AIP Publishing LLC.
Elimination of high concentration hydrogen sulfide and biogas purification by chemical-biological process
(2013-08-01)
Ho, Kuo-Ling
;
Lin, Wei-Chih
;
Chung, Ying-Chien
;
Chen, Yu-Pei
;
Tseng, Ching-Ping
A chemical-biological process was performed to remove a high concentration of H2S in biogas. The high iron concentration tolerance (20 g L-1) of Acidithiobacillus ferrooxidans CP9 provided sufficient ferric iron level for stable and efficient H2S elimination. A laboratory-scale apparatus was setup for a 45 d operation to analyze the optimal conditions. The results reveal that the H2S removal efficiency reached 98% for 1500 ppm H2S. The optimal ferric iron concentration was kept between 9 and 11 g L-1 with a cell density of 10(8) CFU g(-1) granular activated carbon and a loading of 15 g S m(-3) h(-1). In pilot-scale studies for biogas purification, the average inlet H2S concentration was 1645 ppm with a removal efficiency of up to 97% for a 311 d operation and an inlet loading 40.8 g S m(-3) h(-1). When 0.1% glucose was added, the cell density increased twofold under the loading of 65.1 g S m(-3) h(-1) with an H2S removal efficiency still above 96%. The analysis results of the distribution of microorganisms in the biological reactor by DGGE show that microorganism populations of 96.7% and 62.7% were identical to the original strain at day 200 and day 311, respectively. These results clearly demonstrate that ferric iron reduction by H2S and ferrous iron oxidation by A. ferrooxidans CP9 are feasible processes for the removal of H2S from biogas. (C) 2013 Elsevier Ltd. All rights reserved.
Pilot-scale chemical-biological system for efficient H2S removal from biogas
(2013-05-01)
Lin, Wei-Chih
;
Chen, Yu-Pei
;
Tseng, Ching-Ping
;
生物科技學系
;
Department of Biological Science and Technology
A pilot-scale chemical biological process was performed efficiently to remove corrosive H2S from biogas. Consecutive 356-d livestock biogas purification was conducted at various H2S loading rates. The average inlet H2S concentration was 3542 ppm, and a removal efficiency of 95% was achieved with gas retention time of 288 s. This system showed robust performance during operation with stable parameters. Purified biogas with an average of 59% CH4 was collected for power production. Moreover, 28.3 kW h of power was produced by using a 30 kW biogas generator under 300 LPM biogas flow rate. During the 30-d shut down test, the jarosite formation resulted in pH decrease and appearance of Leptospirillum sp. and Sulfobacillus sp. in the bioreactor. However, the cell density of the inoculated Acidithiobacillus ferrooxidans was maintained above 5 x 10(7) CFU/g-AC during long-term operation. Thus, given the successful H2S elimination, the chemical biological process is a feasible system for biogas purification. (C) 2012 Elsevier Ltd. All rights reserved.