Browsing by Issue Date, starting with "2011-06-01"

Now showing 1 - 20 of 41262

Vibrations of rectangular plates with internal cracks or slits
(2011-06-01)
Huang, C. S.
;
Leissa, A. W.
;
Chan, C. W.
;
土木工程學系
;
Department of Civil Engineering
This work applies the famous Ritz method to analyze the free vibrations of rectangular plates with internal cracks or slits. To retain the important and useful feature of the Ritz method providing the upper bounds on exact natural frequencies, the paper proposes a new set of admissible functions that are able to properly describe the stress singularity behaviors near the tips of the crack and meet the discontinuous behaviors of the exact solutions across the crack. The validity of the proposed set of functions is confirmed through comprehensive convergence studies on the frequencies of simply supported square plates with horizontal center cracks having different lengths. The convergent frequencies show excellent agreement with published accurate results obtained by an integration equation technique, and are more accurate than those obtained by a previously published approach using the Ritz method combined with a domain decomposition technique. Finally, the present solution is employed to obtain accurate natural frequencies and mode shapes for simply supported and completely free square plates with internal cracks having various locations, lengths, and angular orientations. Most of the configurations considered here have not been analyzed in the previously published literature. The present results are novel, and are the first published vibration data for completely free rectangular plates with internal cracks and for plates with internal cracks, which are not parallel to the boundaries. (C) 2011 Elsevier Ltd. All rights reserved.
Experimental Study and Modeling of Lapping Using Abrasive Grits with Mixed Sizes
(2011-06-01)
Chung, Chunhui
;
Korach, Chad S.
;
Kao, Imin
;
機械工程學系
;
Department of Mechanical Engineering
In this paper, the lapping process of wafer surfaces is studied with experiments and contact modeling of surface roughness. In order to improve the performance of the lapping processes, effects of mixed abrasive grits in the slurry of the free abrasive machining (FAM) process are studied using a single-sided wafer-lapping machine. Under the same slurry density, a parametric experimental study employing different mixing ratios of large and small abrasive grits and various normal loadings on the wafer surface applied through a jig is conducted. Observations and measurements of the total amount of material removed, material removal rate, surface roughness, and relative angular velocity are presented as a function of various mixing ratios and loadings and discussed in the paper. The experiments show that the 1:1 mixing ratio of abrasives removes more material than other mixing ratios under the same conditions, with a slightly higher surface roughness. Modeling of the mixed abrasive particle distributions correspondingly indicates that the roughness trend is due to the abrasive size distribution and the particle contact mechanics. The results of this study can provide a good reference to the FAM processes that practitioners use today by exploiting different abrasive mixing ratios in slurry and normal loadings in the manufacturing processes. [DOI: 10.1115/1.4004137]
Highly efficient Nd:Gd(0.6)Y(0.4)VO(4) laser by direct in-band pumping at 914 nm and observation of self-mode-locked operation
(2011-06-01)
Liang, H. C.
;
Huang, Y. J.
;
Chiang, P. Y.
;
Chen, Y. F.
;
電子物理學系
A highly efficient Nd:Gd(0.6)Y(0.4)VO(4) laser by direct in-band pumping at 914 nm is demonstrated for the first time. With an absorbed power of 3.7 W, a maximum output power of 2.65 W at 1064 nm was obtained, corresponding to an optical conversion efficiency of 72%. We also experimentally observed that the laser system could be efficiently operated in the self-mode-locked state in the range of 0.9-3.3 GHz. The pulse width was measured to be 16 ps at a repetition rate of 1.75 GHz.
GPU acceleration for general conservation equations and its application to several engineering problems
(2011-06-01)
Kuo, Fang-An
;
Smith, Matthew R.
;
Hsieh, Chih-Wei
;
Chou, Chau-Yi
;
Wu, Jong-Shinn
Presented is a general method for conservation equations called SHLL (split HLL) applied using Graphics Processing Unit (GPU) acceleration. The SHLL method is a purely vector-split approximation of the classical HLL method (Harten et al.. 1983 [1]) which assumes the presence of local wave propagation in the algebraic derivation of fluxes across cell surfaces. The conventional HLL flux expression terms are interface-split and wave propagation velocities estimated (where required) based on local conditions. Due to the highly local nature of the SHLL fluxes, the scheme is very efficiently applied to GPU computation since the flux, initialisation and update phases of the computation are all vectorized processes. The SHLL scheme is applied to GPU computating using Nvidia's CUDA package. Numerical schemes are presented for solutions to the general transport (convection-diffusion) equation, Euler Equations and Shallow Water Equations with results presented for several benchmark gas and shallow water flow engineering problems. Computational times are compared between high-end GPU (Nvidia C1060) and CPU (Intel Xeon 3.0 GHz, 32 MB cache) systems with reported speedups of over 67 times when applied to two dimensional simulations with multi-million cell numbers. (C) 2010 Elsevier Ltd. All rights reserved.
Mechanical and optoelectric properties of post-annealed fluorine-doped tin oxide films by ultraviolet laser irradiation
(2011-06-01)
Tseng, Shih-Feng
;
Hsiao, Wen-Tse
;
Chiang, Donyau
;
Huang, Kuo-Cheng
;
Chou, Chang-Pin
The fluorine-doped tin oxide (FTO) thin film deposited on a soda-lime glass substrate was annealed by a defocus ultraviolet (UV) laser irradiation at ambient temperature. The mechanical and optoelectric properties of FTO films annealed by using the various laser processing parameters were reported. After the FTO films were subjected to laser post-annealing, the microhardness were slightly less but the reduced modulus values were larger than that of unannealed FTO films, respectively. The average optical transmittance in the visible waveband slightly increased with increasing the laser annealing energy and scan speed. Moreover, all the sheet resistance of laser annealed films was less than that of the unannealed ones. We found that the sheet resistance decrease was obviously influenced by annealing. The suitable annealing conditions could maintain the film thickness and relief the internal stress generated in the film preparation process to improve the electrical conductivity via decreasing laser energy or increasing scan speed. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.
Controlling number of lasing modes for designing short-cavity self-mode-locked Nd-doped vanadate lasers
(2011-06-01)
Chen, Y. F.
;
Huang, Y. J.
;
Chiang, P. Y.
;
Lin, Y. C.
;
Liang, H. C.
A short-cavity Nd:YVO(4) laser is employed to confirm that a spontaneous mode locking (SML) typically occurs without employing an extra nonlinearity. We further experimentally demonstrate that reducing the number of longitudinal lasing modes can diminish the phase fluctuation and effectively improve the SML pulse stability. Considering the spatial hole-burning (SHB) effect, an analytical expression is derived to accurately estimate the number of longitudinal lasing modes for a practical design guideline.
Attention-based high dynamic range imaging
(2011-06-01)
Lin, Wen-Chieh
;
Yan, Zhi-Cheng
;
資訊工程學系
;
多媒體工程研究所
;
Department of Computer Science
Many tone mapping algorithms have been proposed based on the studies in Human Visual System; however, they rarely addressed the effects of attention to contrast response. As attention plays an important role in human visual system, we proposed a local tone mapping method that respects both attention and adaptation effects. We adopt the High Dynamic Range (HDR) saliency map to compute an attention map, which predicts the attentive regions and nonattentative regions in an HDR image. The attention map is then used to locally adjust the contrast of the HDR image according to attention and adaptation models found in psychophysics. We applied our tone mapping approach to HDR images and videos and compared with the results generated by three state-of-the-art tone mapping algorithms. Our experiments show that our approach produces results with better image quality in terms of preserving details and chromaticity of visual saliency.
Annealing treatment improves the morphology and performance of photovoltaic devices prepared from thieno[3,4-c]pyrrole-4,6-dione-based donor/acceptor conjugated polymers and CdSe nanostructures
(2011-06-01)
Kuo, Chih-Yin
;
Su, Ming-Shi
;
Chen, Guan-Yu
;
Ku, Ching-Shun
;
Lee, Hsin-Yi
We have prepared photovoltaic devices based on blend films of CdSe tetrapods and the donor/acceptor conjugated polymer PDTTTPD, which comprises 2,5-di(thiophen-2-yl) thieno[3,2-b]thiophene and thieno[3,4-c]pyrrole-4,6-dione units. The AM1.5 power conversion efficiency (PCE) of a photovoltaic device containing a PDTTTPD/CdSe tetrapod blend (1:9, w/w) that had experienced thermal annealing (130 degrees C, 20 min) was three times greater than that of the corresponding device incorporating the as-prepared PDTTTPD/CdSe tetrapod blend (2.9% vs. 1.0%). Synchrotron X-ray reflectivity revealed that annealing (i.e., removal of pyridine ligands from the surfaces of the CdSe tetrapods) caused the thickness of the PDTTTPD/CdSe tetrapod blend film to decrease (and its average density to increase) relative to that of the as-prepared blend film. Transmission electron microscopy and atomic force microscopy revealed that thermal annealing enhanced the degree of aggregation of the CdSe tetrapods and induced denser morphologies, leading to substantially increased charge transport, which enhanced the PCE of the device.
具有三五族通道及四族源汲極之半導體裝置及其製造方法
(2011-06-01)
張俊彥
本發明係關於具有三五族通道及四族源汲極之半導體裝置及其製造方法，具體而言，係藉由三五族與四族材料的異質磊晶及元件的結構設計來提高三五族材料的能階密度及摻雜濃度。該方法包括：製備基板；在該基板上沉積假閘極材料層，利用微影法將該假閘極材料層定義出假閘極；以該假閘極作為遮罩實施自我對準式離子佈植而進行摻雜，進行高溫活化而形成源汲極；去除該假閘極；藉由蝕刻，在成對之該源汲極之間的該基板形成凹陷；在該凹陷中磊晶形成包含通道之堆疊元件；及在該包含通道之堆疊元件上形成閘極。
3-Cell Network MIMO Architectures with Sectorization and Fractional Frequency Reuse
(2011-06-01)
Wang, Li-Chun
;
Yeh, Chu-Jung
;
傳播研究所
;
電機工程學系
;
Institute of Communication Studies
In this paper, we present a 3-cell network multiple-input multiple-output (MIMO) architecture with fractional frequency frequency (FFR) and a novel tri-sector frequency partition scheme. One fundamental question to apply the network MIMO technique in such a high interference environment is: how many base stations should be coordinated together to provide sufficient performance? We will demonstrate that the FFR-based 3-cell network MIMO architecture with the proposed tri-sector frequency partition can not only effectively overcome the inter-group interference, but can avoid executing the complex multibase-station joint processing for a huge number of cluster of cells at all locations. It will be shown that the proposed 3-cell network MIMO with the rearranged tri-sector frequency partition strategy can outperform the 7-cell network MIMO with omni-directional antennas. Various sector antenna architectures and the method for determining the inner region of the FFR cell planning are also discussed and analyzed on top of the network MIMO system. We hope that this study can provide important insights into the design of the network MIMO systems from the perspectives of architecture and deployment.
Performance Analysis on Planar Micro PDMS Proton Exchange Membrane Fuel Cell Stack
(2011-06-01)
Peng, Rong-Gui
;
Chen, Tang-Yuan
;
Hsu, Yi-Ja
;
Chen, Chiun-Hsun
;
機械工程學系
The objective of this study is to develop a micro proton exchange membrane fuel cell (PEMFC) stack, in which a flow field plate in each cell is made of polydimethyl-siloxane (PDMS) and manufactured by micro-molding technology. A four-cell micro PEMFC stack in series with a volume of 12 cm x 4.5 cm x 1.2 cm is constructed and tested. The active area of a membrane electrode assembly (MEA) is 2 cm x 2 cm in each individual PEMFC, and the platinum loadings at anode and cathode are 0.3 and 0.5 mg/cm(2), respectively. A series of performance experiments were carried out. Experimental parameters included clamping force and fuel supply condition. Durability tests were carried out as well. Experimental results showed that an appropriate clamping torque range should be considered carefully to enhance performance without narrowing down fuel flow channels. Under a torque of 2.0 kgf . cm, peak power density for this stack is 122.5 mW/cm(2) at 2.0 V. Increase in fuel flow rate is not the best way to improve concentration polarization in this air-breathing stack experiment because of limited air supply, and each cell in the same stack has a different performance under the present arrangement. At present, such stack can maintain a stable power output for a long time (up to 14 hours).
一種非晶系氧化物半導體的光感測器裝置與其製作方法
(2011-06-01)
劉柏村
;
鄒一德
;
鄧立峯
本發明係提供一種非晶系氧化物半導體之光感測器裝置與其製作方法，特色在於新氧化物感光材料以應用於主動式顯示面板上，可以對其外在光產生特殊光感應，並維持一段時間特性不改變；亦可藉由電壓施加方式，令其原特性快速恢復。
一種應用資訊檢索技術之智慧型行動式服務商品評鑑系統與方法
(2011-06-01)
羅濟群
;
龔旭陽
;
陳志華
;
程鼎元
;
呂志健
本發明係一種應用資訊檢索技術之智慧型行動式服務商品評鑑系統與方法，其係結合即時商品辦識系統（Real-Time Merchandise Identifying System,RMIS）、商品評論建議系統(Merchandise Evaluating System,MES)、以及商品比價推薦系統（Merchandise Recommandation System,MRS）以提供即時之商品評鑑服務(Merchandise Evaluate Service,MES)以推薦相關之商品，並利用自我組織類神經網路(Self-Organizing Maps,SOM)學習各個商品特徵，並有效進行分類，結合多文件自動摘要技術（Multiple Document Summarization,MDS）幫助消費者於短時間內判斷及取得重要購買決策參考資訊。
Enhanced omnidirectional photon coupling via quasi-periodic patterning of indium-tin-oxide for organic thin-film solar cells
(2011-06-01)
Tseng, Ping-Chen
;
Hsu, Min-Hsiang
;
Tsai, Min-An
;
Chu, Chih-Wei
;
Kuo, Hao-Chung
Enhanced optical coupling via an indium tin oxide quasi-periodic structure (ITO-QPS) as the frontal electrode for organic thin film solar cells was demonstrated. The QPS was fabricated via scalable polystyrene colloidal lithography, which effectively coupled the incident light to the photo-active layer through antireflection and light-trapping mechanisms. The cell efficiency was boosted from 2.91% to 3.26%, corresponding to a 12% enhancement after ITO patterning. Moreover, the angle-resolved absorption spectroscopy also confirmed excellent light coupling at large angles of incidence to 45 degrees, particularly in the wavelength range between 540 and 670 nm. The ITO-QPS guarantees broadband and omnidirectional light harvesting and is widely applicable to a variety of thin film solar cells. (C) 2011 Elsevier B.V. All rights reserved.
Electrical Characterization of Al2O3/n-InAs Metal-Oxide-Semiconductor Capacitors With Various Surface Treatments
(2011-06-01)
Trinh, H. D.
;
Brammertz, G.
;
Chang, E. Y.
;
Kuo, C. I.
;
Lu, C. Y.
Ex situ sulfide and HCl wet chemical treatments in conjunction with in situ trimethyl aluminum (TMA) pretreatment were performed before the deposition of Al2O3 on n-InAs surfaces. X-ray photoelectron spectroscopy analyses show a significant reduction of InAs native oxides after different treatments. The capacitance-voltage C-V characterization of Al2O3/n-InAs structures shows that the frequency dispersion in the accumulation regime is small (< 0.75%/dec) and does not seem to be significantly affected by the different surface treatments, whereas the latter improves depletion and inversion behaviors of the n-channel metal-oxide-semiconductor capacitors. The interface trap density profiles extracted from the simulation mainly show donorlike interface states inside the InAs band gap and in the lower part of the conduction band. The donorlike traps inside the InAs band gap and in the lower part of the conduction band were significantly reduced by using wet-chemical-plus-TMA treatments, in agreement with C-V characteristics.
Method for Determining the Angle in Two Dimension Nanoscale: Pitch Grating
(2011-06-01)
Pan, Shan-Peng
;
Liu, Tzong-Shi
;
Tasi, Min-Ching
;
Liou, Huay-Chung
;
機械工程學系
A two-dimensional (2D) grating is useful for calibrating the accuracy of an electron microscope and atomic force microscope (AFM). An inter laboratory comparison has been carried out for measuring pitches and angles of 2D gratings with 292 and 1000nm pitches using both AFM and an optical diffractometer (OD). The grating angle at the 292nm pitch size was obtained at some of the laboratories by the conventional OD method. However, they could not measure the grating angle when the grating pitch was smaller than (lambda/2) x root 2, where lambda denotes the laser wavelength. We propose a diffraction angle rotation method of grating angle measurements. Using a precision rotary table along with diffractive light, we accurately measure a 2D grating angle for any pitch size larger than lambda/2. (C) 2011 The Japan Society of Applied Physics
融合教育下適應體育發展與方向
(國立交通大學體育室, 2011-06-01)
施敬洲
;
劉佳哲
;
張碧峰
;
詹益欣
;
Ching-Chou Shih
適應體育包含了所有可用於身心障礙者的適性體育活動。目前國內各級學校的身心障礙學生，約有八成接受融合式教育安置；在此種特殊教育安置型態下的適應體育教學，必須更加著重身障學生之個別差異，針對殘存能力加以調整教材教法，提供符合其現況能力之體育教學活動。期望藉由教師事先的規劃設計，讓學生能縮小與同儕間的差距，融入各項體育教學活動之中。
ON THE RATE OF CONVERGENCE OF BINOMIAL GREEKS
(2011-06-01)
Chung, San-Lin
;
Hung, Weifeng
;
Lee, Han-Hsing
;
Shih, Pai-Ta
;
資訊管理與財務金融系註：原資管所+財金所
This study investigates the convergence patterns and the rates of convergence of binomial Greeks for the CRR model and several smooth price convergence models in the literature, including the binomial Black-Scholes (BBS) model of Broadie M and Detemple J (1996), the flexible binomial model (FB) of Tian YS (1999), the smoothed payoff (SPF) approach of Heston S and Zhou G (2000), the GCRR-XPC models of Chung SL and Shih PT (2007), the modified FB-XPC model, and the modified GCRR-FT model. We prove that the rate of convergence of the CRR model for computing deltas and gammas is of order O(1/n), with a quadratic error term relating to the position of the final nodes around the strike price. Moreover, most smooth price convergence models generate deltas and gammas with monotonic and smooth convergence with order O(1/n). Thus, one can apply an extrapolation formula to enhance their accuracy. The numerical results show that placing the strike price at the center of the tree seems to enhance the accuracy substantially. Among all the binomial models considered in this study, the FB-XPC and the GCRR-XPC model with a two-point extrapolation are the most efficient methods to compute Greeks. (C) 2010 Wiley Periodicals, Inc. Jrl Fut Mark 31:562-597, 2011
Grating Pitch Measurement Beyond the Diffraction Limit with Modified Laser Diffractometry
(2011-06-01)
Pan, Shan-Peng
;
Liu, Tzong-Shi
;
Tasi, Min-Ching
;
Liou, Huay-Chung
;
機械工程學系
The demand for accurate measurements of nanostructures is increasing for the microprocesses and nanotechnology used in the semiconductor industry. In this study, we present an improved method for measuring gratings with a pitch size lower than one-half of the laser wavelength by using a modified laser diffractometer (LD). In experiments, the modified LD with a 633nm laser is used to measure a grating with a 288nm pitch size. This result is compared with results measured by both a metrological atomic force microscope and the traditional LD with a 543nm laser. The validity of this method is demonstrated. The difference between the pitch size of 288nm obtained by these three methods is approximately 0.17 nm. (C) 2011 The Japan Society of Applied Physics
Highly efficient Nd:Gd0.6Y0.4VO4 laser by direct in-band pumping at 914 nm and observation of self-mode-locked operation
(2011-06-01)
Liang, H. C.
;
Huang, Y. J.
;
Chiang, P. Y.
;
Chen, Y. F.
;
電子物理學系
A highly efficient Nd:Gd0.6Y0.4VO4 laser by direct in-band pumping at 914 nm is demonstrated for the first time. With an absorbed power of 3.7 W, a maximum output power of 2.65 W at 1064 nm was obtained, corresponding to an optical conversion efficiency of 72%. We also experimentally observed that the laser system could be efficiently operated in the self-mode-locked state in the range of 0.9-3.3 GHz. The pulse width was measured to be 16 ps at a repetition rate of 1.75 GHz.