Browsing by Author "Chen, Yen-Chang"

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Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions
(2016-12-07)
Ishihara, Hidetaka
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Chen, Yen-Chang
;
De Marco, Nicholas
;
Lin, Oliver
;
Huang, Chih-Meng
The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.
Enhanced fight transmission for Si solar cells using anti-reflector of mesoporous silica with low refractive index
(2007)
Shieh, Jia-Min
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Wang, Chao-Kei
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Wu, Shich-Chuan
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Ni, Wei-Xin
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Kuo, Hao-Chung
Mesoporus silica dielectrics, which revealed low refractive index (n similar to 1.27), were introduced together with Si3N4 layers to be double-layer-based graded-refractive-index ant-reflectors for silicon solar-cells. Enhanced solar-light transmission increased conversion efficiency of Si solar panels by 20%.
Enhanced solar-light transmission by broadband anti-reflective structure with mesoporous silica of low refractive index
(2008)
Wang, Chao-Kei
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Shieh, Jia-Min
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Wu, Shich-Chuan
;
Yu, Wen-Chien
;
Kuo, Hao-Chung
Mesoporus silica dielectrics, which revealed low refractive index (n similar to 1.26), were introduced together with Si3N4 layers to be double-layer-based graded-refractive-index ant-reflectors for silicon solar-cells. Enhanced solar-light transmission increased conversion efficiency of Si solar panels by 4%.
On the Accumulated Loopback Self-Interference of Two-Way Full-Duplex AF Relaying Systems
(2019-05-01)
Chang, Min-Kuan
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Chien, Feng-Tsun
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Kuo, Chih-Hung
;
Chen, Yen-Chang
;
交大名義發表
Two-way full-duplex (TWFD) transmissions in cooperative amplify-and-forward (AF) relaying systems provide a promising way of communications with the improved spectral efficiency by concurrently transmitting/receiving data in the same frequency band and by the two-way transmission protocol. However, the loopback self-interference, caused by the imperfect channel estimation in the loopback link, at the AF relay accumulates and is forwarded to the end users recurrently, which substantially degrades the end users' error performance if this accumulated loopback self-interference (ALSI) does not converge. It is therefore of critical importance to analyze the convergence behavior of the ALSI in the TWFD systems with AF relaying. In this paper, we establish sufficient conditions on the relay power to ensure the convergence of the ALSI, with which the average limiting signal-to-interference-plus-noise ratio at the infinite time horizon is derived. In addition, we specify the relay power at which the signal-to-noise ratio reaches the maximal value under different scenarios and obtain an upper bound to the symbol error rate. Finally, extensive computer simulations results are provided to corroborate the analytic derivations.
Uncertainties in the Methods of Flood Discharge Measurement
(2013-01-01)
Chen, Yen-Chang
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Hsu, Yung-Chia
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Kuo, Kuang-Ting
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防災與水環境研究中心
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Disaster Prevention and Water Environment Research Center
This study demonstrates an application of uncertainty analysis in evaluating methods of discharge measurement including: the velocity-area, rating curve and efficient methods based on the probabilistic velocity distribution equation. The measurement of river discharge plays a large part in the distribution of water resources. The conventional methods of discharge measurement are costly, time-consuming, and dangerous. Therefore the efficient method of discharge measurement which bases on the relationship between maximum and mean velocities being constant was employed to justify its alternative for the conventional methods: velocity-area and rating curve methods. Distribution test was applied to investigate the statistical properties of the uncertainties involved in the three methods of discharge measurement. Latin hypercube sampling (LHS) method was employed accordingly to assess the discharge features of the three methods of discharge measurement. The main purpose of this study is to quantify the uncertainty involved in several discharge measurement methods and justify the availability and reliability of using the efficient method as an alternative of the conventional methods. Results show that the correlation analysis also validates that the efficient method is a more reliable method than the rating curve method to yield accurate discharge measurements. Moreover, it also yielded comparably accurate measurements as those by the velocity-area method.
Vehicular Signal Transmission Using Power Line Communications
(2012)
Chen, Yen-Chang
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Tsai, Shang-Ho
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Yang, Kai-Jiun
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Ho, Ping-Fan
;
Tseng, Kuo-Feng
We propose a power line communication (PLC) system for transmitting control signals in vehicle through internal power lines, such that the internal wires can be reduced and the vehicles can be lighter. The signals from different devices are multiplexed and modulated to the power lines by the transmitter. In the receiver, first the noise within power lines are filtered. Afterwards the multiplexed signals are selectively extracted by specific codes which are minimally correlated. Finally the control signals are restored from the error-control coded bits which make the information more robust. The maximum data rate of the chip is 50 kbps, and the die area is 3.74 mm(2) using a TSMC 0.18 mu m standard cell library with power consumption 22.49 mW.