Browsing by Author "Wang, Chih-Yu"

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A High-Accuracy Multidomain Legendre Pseudospectral Frequency-Domain Method With Penalty Scheme for Solving Scattering and Coupling Problems of Nano-Cylinders
(2013-03-01)
Wang, Chih-Yu
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Chung, Shih-Yung
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Teng, Chun-Hao
;
Wang, Juen-Kai
;
Chen, Chung-Ping
A new multidomain pseudospectral frequency-domain (PSFD) method based on the Legendre polynomials with penalty scheme is developed for numerically modeling electromagnetic wave scattering problems. The primary aim of the proposed method is to more accurately analyzing scattering and coupling problems in plasmonics, in which optical waves interact with nanometer-sized metallic structures. Using light scattering by a silver circular cylinder as a first example, the formulated method is demonstrated to achieve numerical accuracy in near-field calculations on the order of 10(-9) with respect to a unity field strength of the incident wave with excellent exponentially convergent behavior in numerical accuracy. Then, scattering by a dielectric square cylinder and that by several coupled metallic structures involving circular cylinders, square cylinders, or dielectric coated cylinders are examined to provide high-accuracy coupled near-field results.
A Multidomain Pseudospectral Mode Solver for Optical Waveguide Analysis
(2012-07-01)
Chiang, Shun-Fan
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Lin, Bang-Yan
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Chang, Hung-Chun
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Teng, Chun-Hao
;
Wang, Chih-Yu
We propose a pseudospectral mode solver for optical waveguide mode analysis formulated by the frequency-domain Maxwell equations. Special attention is paid upon identifying the required boundary operator for the formulation and the relationships between the derived operator and the physical boundary conditions. These theoretical results are adopted into a Legendre pseudospectral multidomain computational framework to compute the propagation characteristics of optical waveguides. Numerical experiments are conducted, and the expected spectral convergence of the scheme is observed for smooth problems and for problems having field jumps at material interfaces. For dielectric waveguides with sharp corners, the spectral convergence is lost due to the singular nature of fields at the corner. Nevertheless, compared with other methods, the present formulation remains as an efficient approach to obtain waveguide modes.
Comparison of the performance of linear multivariate analysis methods for normal and dyplasia tissues differentiation using autofluorescence spectroscopy
(2006-11-01)
Chu, Shou Chia
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Hsiao, Tzu-Chien Ryan
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Lin, Jen K.
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Wang, Chih-Yu
;
Chiang, Huihua Kenny
We compared the performance of three widely used linear multivariate methods for autofluorescence spectroscopic tissues differentiation. Principal component analysis (PCA), partial least squares (PLS), and multivariate linear regression (MVLR) were compared for differentiating at normal, tubular adenoma/epithelial dysplasia and cancer in colorectal and oral tissues. The methods' performances were evaluated by cross-validation analysis. The group-averaged predictive diagnostic accuracies were 85% (PCA), 90% (PLS), and 89% (MVLR) for colorectal tissues; 89% (PCA), 90% (PLS), and 90% (MVLR) for oral tissues. This study found that both PLS and MVLR achieved higher diagnostic results than did PCA.
Education system integration in cross-disciplinary with colleges - Virtual biomedical instrument (VBI) for example
(2008-06-01)
Hsiao, Tzu-Chien
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Chang, Chia-Chi
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Liu, Chien-Sheng
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Lin, Chii-Wann
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Wang, Chih-Yu
Due to the rapid development of computer science, software, and biomedical engineering, many clinical diagnosis instruments and control system improved accordingly. The minimization and practicality of sensors, as well as the efficiency and stability of computers make simulation control system in medical instruments become the most important part of developing items. The relevant subject of course, virtual biomedical instrumentations (VBI), which combined with computer science, electrical engineering, and medical science, has become a major developing course in biomedical education. Cross-disciplinary research needs experts in different areas and most cross-disciplinary schools cannot afford it. So it requires integration and cooperation between schools. To address this issue, a graduated course has been designed to provide an opportunity for all professions in each field to discuss and share their resources on an e-learning platform. With the progress of the project, VBI course integrates biomedical education resources from north to south colleges to reduce the request of manpower for cross-disciplinary course of biomedical. In addition, VBI courses initiate the cooperation between academic community and industry.
Exact Performance of NOMA with Full-Duplex Energy Harvesting Relaying in Nakagami-m Frequency-Selective Fading Channel
(2018-01-01)
Wang, Szu-Liang
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Wang, Chih-Yu
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Chung, Wei-Ho
;
交大名義發表
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National Chiao Tung University
In this paper, the NOMA transmission with fullduplex energy harvesting relaying ( FDEHR) is investigated. Closed-form expressions for the outage probability of the near and far users are presented over Nakagami-m frequency-selective fading channel. Monte Carlo simulations are provided throughout to verify the accuracy of the derivations. Simulation and numerical results demonstrate that the near user without FDEHR possesses lower outage probability than the far user. While the outage performance of the far user could be improved and better than the near user with FDEHR.
Facile Synthesis of Radial-Like Macroporous Superparamagnetic Chitosan Spheres with In-Situ Co-Precipitation and Gelation of Ferro-Gels
(2012-11-30)
Yang, Chih-Hui
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Wang, Chih-Yu
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Huang, Keng-Shiang
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Yeh, Chen-Sheng
;
Wang, Andrew H. -J.
Macroporous chitosan spheres encapsulating superparamagnetic iron oxide nanoparticles were synthesized by a facile and effective one-step fabrication process. Ferro-gels containing ferrous cations, ferric cations and chitosan were dropped into a sodium hydroxide solution through a syringe pump. In addition, a sodium hydroxide solution was employed for both gelation (chitosan) and co-precipitation (ferrous cations and ferric cations) of the ferro-gels. The results showed that the in-situ co-precipitation of ferro-ions gave rise to a radial morphology with non-spheroid macro pores (large cavities) inside the chitosan spheres. The particle size of iron oxide can be adjusted from 2.5 nm to 5.4 nm by tuning the concentration of the sodium hydroxide solution. Using Fourier Transform Infrared Spectroscopy and X-ray diffraction spectra, the synthesized nanoparticles were illustrated as Fe3O4 nanoparticles. In addition, the prepared macroporous chitosan spheres presented a super-paramagnetic behaviour at room temperature with a saturation magnetization value as high as ca. 18 emu/g. The cytotoxicity was estimated using cell viability by incubating doses (0 similar to 1000 mu g/mL) of the macroporous chitosan spheres. The result showed good viability (above 80%) with alginate chitosan particles below 1000 mu g/mL, indicating that macroporous chitosan spheres were potentially useful for biomedical applications in the future.
High-Accuracy Waveguide Leaky-Mode Analysis Using a Multidomain Pseudospectral Frequency-Domain Method Incorporated With Stretched Coordinate PML
(2013-07-15)
Wang, Chih-Yu
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Liu, Hsuan-Hao
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Chung, Shih-Yung
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Teng, Chun-Hao
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Chen, Chung-Ping
A recently developed pseudospectral frequency-domain (PSFD) method employing a penalty scheme is further incorporated with stretched coordinate perfectly matched layers (PMLs) in order to solve waveguide leaky modes. Several standard leaky-mode slab and circular waveguides, including the W-type and M-type ones, are examined first by solving their complex effective indexes and field profiles, showing that the PSFD method achieves computational accuracy on the order of. Then, this high-accuracy solver is used to analyze waveguide structures with more complicated geometries, such as the leaky six-air-hole fiber, for which self convergence of accuracy in calculated effective indexes is demonstrated to be on the orders of, and two rectilineal waveguides with sharp corners, i.e., the rib waveguide and the photonic wire. Comparison of the PSFD method obtained results for these more complicated waveguide structures with those from other methods in the literature is presented and discussed.
Investigation of Nanoelectromagnetics Problems Using the Multidomain Legendre Pseudospectral Time-Domain Method
(2012)
Chang, Hung-chun
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Chung, Shih-Yung
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Wang, Chih-Yu
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Teng, Chun-Hao
;
Wang, Juen-Kai
Nanoelectromagnetics problems in nanophotonics and plasmonics in the optical-wavelength regime are concerned in this paper. Very often such problems demand more accurate electromagnetic computation and analysis. A multidomain Legendre pseudospectral time-domain (PSTD) method recently developed and demonstrated to provide high numerical accuracy is utilized to study light interaction with sub-wavelength three-dimensional plasmonic structures and associated plasmonic resonances. With the multidomain technique, the simulation region is partitioned into curvilinear hexahedral subdomains with better fitting to the structural shapes and material interfaces so as to achieve high-accuracy near-field calculations. Light scattering by multiple plasmonic nanospheres and light transmission through a metallic thin film perforated with periodic apertures are investigated with the PSTD analysis.
Mechanism in determining pretilt angle of liquid crystals aligned on fluorinated copolymer films
(2009-08-07)
Wu, Hsin-Ying
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Wang, Chih-Yu
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Lin, Chia-Jen
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Pan, Ru-Pin
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Lin, Song-Shiang
This work explores the surface treatment of copolymer materials with fluorinated carbonyl groups in various mole fractions by ultraviolet irradiation and ion-beam (IB) bombardment and its effect on liquid crystal (LC) surface alignments. X-ray photoemission spectroscopic analysis confirms that the content of the grafted CF(2) side chains dominates the pretilt angle. A significant increase in oxygen content is responsible for the increase in the polar surface energy during IB treatment. Finally, the polar component of the surface energy dominates the pretilt angle of the LCs.
Microfluidic Synthesis of Microfibers for Magnetic-Responsive Controlled Drug Release and Cell Culture
(2012-03-28)
Lin, Yung-Sheng
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Huang, Keng-Shiang
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Yang, Chih-Hui
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Wang, Chih-Yu
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Yang, Yuh-Shyong
This study demonstrated the fabrication of alginate microfibers using a modular microfluidic system for magnetic-responsive controlled drug release and cell culture. A novel two-dimensional fluid-focusing technique with multi-inlets and junctions was used to spatiotemporally control the continuous laminar flow of alginate solutions. The diameter of the manufactured microfibers, which ranged from 211 mm to 364 mm, could be well controlled by changing the flow rate of the continuous phase. While the model drug, diclofenac, was encapsulated into microfibers, the drug release profile exhibited the characteristic of a proper and steady release. Furthermore, the diclofenac release kinetics from the magnetic iron oxide-loaded microfibers could be controlled externally, allowing for a rapid drug release by applying a magnetic force. In addition, the successful culture of glioblastoma multiforme cells in the microfibers demonstrated a good structural integrity and environment to grow cells that could be applied in drug screening for targeting cancer cells. The proposed microfluidic system has the advantages of ease of fabrication, simplicity, and a fast and low-cost process that is capable of generating functional microfibers with the potential for biomedical applications, such as drug controlled release and cell culture.
Pair Auction and Matching for Resource Allocation in Full-Duplex Cellular Systems
(2020-04-01)
Chao, Cheng-Chih
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Wang, Chih-Yu
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Lee, Chia-Han
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Wei, Hung-Yu
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Chen, Wen-Tsuen
Full-duplex techniques improve spectral efficiency in cellular networks by allowing a transceiver to simultaneously transmit and receive data with the same radio resource. To minimize self-interference and inter-node interference due to the deployment of full-duplex radio, users have to feed back their measurements of interference to allow the base station to effectively allocate resources and form transmission pairs. Considering that the interference measurements are private information, users may not report the true values and may try to gain their own benefits. To solve this problem, we propose a strategy-proof resource allocation mechanism for full-duplex cellular networks. The proposed scheme, which is based on auction and matching theories, guarantees that users report true values of their channel quality and utilities, and therefore guarantees the correctness of feedback information and the efficiency of resource allocation. Moreover, the proposed matching-based mechanism is theoretically proved to be stable and Pareto efficient. Simulation results confirm that, compared to a centralized scheme with non-truthful information from users, the proposed scheme can achieve an 11% gain.
Simulations of Dielectric and Plasmonic Waveguide-Coupled Ring Resonators Using the Legendre Pseudospectral Time-Domain Method
(2012-06-01)
Chung, Shih-Yung
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Wang, Chih-Yu
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Teng, Chun-Hao
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Chen, Chung-Ping
;
Chang, Hung-Chun
The accurate Legendre pseudospectral time-domain (PSTD) method is applied in this paper to the study of optical behaviors of 2-D dielectric and plasmonic waveguide-coupled ring resonators. Based on its inherent multidomain scheme with curvilinear-quadrilateral subdomain partitioning, the PSTD method possesses superior advantage in fulfilling field continuity conditions across material interfaces, which provides better numerical handling upon circular or even more complicated ring structures. Accordingly, investigations of several plasmonic nanoring resonators of different shapes with surface plasmon polariton (SPP) waves propagating on the metal/dielectric/metal waveguides are made with the aids of a well-fitted Drude-Lorentz material-dispersion model through analyzing their characteristics in the near-infrared and visible parts of the light spectrum. Especially, the racetrack-shaped ring is carefully designed with optimized track length to avoid the over-or under-coupling problem between the ring and input waveguides and, thus, achieve excellent spectral performance.
Solving Optical Waveguide Leaky Modes Using a Multidomain Legendre Pseudospectral Frequency-Domain Method
(2013)
Wang, Chih-Yu
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Chung, Shih-Yung
;
Teng, Chun-Hao
;
Chen, Chung-Ping
;
Chang, Hung-chun
A Legendre pseudospectral frequency-domain (PSFD) method incorporated with stretched coordinate perfectly matched layers (PMLs) and a multidomain technique is established for solving optical waveguide leaky modes. A recently developed penalty scheme is employed to assure numerical accuracy. This high-accuracy solver is used to analyze a leaky six-air-hole microstructured fiber, for which self convergence of accuracy in calculated effective indexes is demonstrated to be on the orders of 10(-14). Then, the photonic wire is analyzed and the comparison with the analysis results from other methods is discussed.
Surface Alignment with High Pretilt Angle Using the Photoreactive Fluorinated Polymer Films
(2009)
Wu, Hsin-Ying
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Wang, Chih-Yu
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Lin, Chia-Jen
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Pan, Ru-Pin
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Lin, Song-Shiang
A newly developed fluorinated polymer film for liquid crystal alignment by applying ultra-violet (UV) irradiation or ion beam treatment is studied in this work. The surface alignment with high pretilt angle is achieved by the UV treatment. The induced pretilt angle by ion beam treatment on this photo-reactive polymer film, however, is relatively small. Surface analyses by x-ray photoemission spectroscopy and contact angle measurement are carried out to deduce the underlying mechanism. The result shows that the higher content of the fluorinated side-chain in polymer contribute to the lower surface energy and the higher pretilt angle. The atomic ratio of fluorine is largely decreased by ion beam treatments. The alignment uniformity and stability of the surfaces treated by linearly-polarized UV light and ion beam bombardment are also demonstrated.
Synthesis of uniform core-shell gelatin-alginate microparticles as intestine-released oral delivery drug carrier
(2014-02-01)
Huang, Keng-Shiang
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Yang, Chih-Hui
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Kung, Chao-Ping
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Grumezescu, Alexandru Mihai
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Ker, Ming-Dou
A core-shell gelatin-alginate composite used for intestine-released oral delivery drug carrier was synthesized through microfluidic technique. At the fixed continuous phase flow rate, the size of the core-shell gelatin-alginate microparticles increases with the dispersed phase flow rate, and monodispersity can be retained (the variation coefficient for the diameter distribution can be kept less than 10%). The fabricated microparticles could remain intact in gastric juice for at least 3 h, indicating that the gelatin core could be well protected by alginate shell in acid environment. However, the alginate shell of the microparticles would swell or collapse in alkali environment in half an hour, assuring the controlled drug release in intestinal juice. The fabricated uniform core-shell gelatin-alginate microparticles were potential as pH-responsive drug carriers.