Browsing by Issue Date, starting with "2018-09"

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Pseudopolymorph Control of L-Phenylalanine Achieved by Laser Trapping
(2018-09-01)
Wu, Chi-Shiun
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Hsieh, Pei-Yun
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Yuyama, Ken-ichi
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Masuhara, Hiroshi
;
Sugiyama, Teruki
We demonstrate pseudopolymorph control of L-phenylalanine (L-Phe) with laser trapping method by tuning laser power, polarization, and initial solution concentration. When a continuous-wave near-infrared laser beam of 1064 nm was focused at an air/solution interface of L-Phe D2O solutions with different saturation, L-Phe crystallization was always observed within 30 min-irradiation, even from unsaturated solution. Either whisker- or plate-like crystals were generated depending on given conditions, and identified by Raman spectroscopy to be two L-Phe pseudopolymorphs of monohydrate and anhydrous forms, respectively. The absolute control of L-Phe pseudopolymorphism was achieved by changing the initial solution concentration. In unsaturated solution, laser trapping always produced only one anhydrous crystal at the focus, which can never be produced on spontaneous nucleation at ordinary temperatures and pressures, while in supersaturated solution, a number of monohydrate crystals were densely distributed in an area ranging from 500 mu m to 1 mm away from the focus. Moreover, in saturated solution, laser power and polarization contributed to the pseudopolymorphism. As laser power was increased, linearly and circularly polarized laser irradiation increased the formation probability of the anhydrous and monohydrate crystals, respectively. The dynamics and mechanism of laser trapping-induced pseudopolymorphism of L-Phe are discussed in view of the formation of a highly concentrated domain consisting of the liquid-like clusters and the stability of the clusters in the domain under electromagnetic field of trapping laser.
Orthogonally Polarized Self-Mode-Locked Lasers With Repetition Rate Multiplication up to Hundreds of Gigahertz: Observation of Temporal Carpets
(2018-09-01)
Chen, Yung-Fu
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Chang, Ming-Ting
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Huang, Tzu-Lin
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Tung, Jung-Chen
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Huang, Kai-Feng
Mode-locked laser sources with high repetition rates in the range of 10-1000 GHz are of considerable interest in modern communications, optical metrology, and photonic applications. Currently, developed laser systems generally suffer from the hardware complexity and energy loss. Here, we demonstrate a compact robust scheme based on a self-mode-locked monolithic Yb:KGW laser with external feedback coupling to achieve numerous repetition rate multiplications in the range of 25-330 GHz. The output pulse train consists of two orthogonally polarized components to form a vector state that is beneficial to practical applications. More intriguing, the pulse train measured as a function of the distance of the coupling feedback reveals a feature of the fractional recurrence that is like the Talbot carpet. An analytic formula is derived to manifest the formation of the temporal carpets. The developed experiment and formula not only pave a useful way for generating ultrahigh-repetition-rate femtosecond lasers but also provide new perspectives in the fractional recurrences of coherent waves.
Promising Er3+/Yb3+-Codoped GdBiW2O9 Phosphor for Temperature Sensing by Upconversion Luminescence
(2018-09-01)
Dutta, Somrita
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Som, Sudipta
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Chen, Teng-Ming
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應用化學系
;
Department of Applied Chemistry
Yb3+/Er3+-codoped GdBiW2O9 phosphors are prepared via the solidstate route for application in upconversion temperature sensors. The structural analyses indicate that all phosphors possess a single-phased orthorhombic structure. Upon the excitation of a laser wavelength of 980 nm, Yb3+/Er3+-codoped GdBiW2O9 phosphors emanate green emission peaks, endorsed to the emission to the I-4(15/2) state from the S-4(3/2) and H-2(11/2) states, respectively, and the weak emission (red) from the F-4(9/2) state to the I-4(15/2) state of Er3+ ion. The upconversion mechanism has been elucidated via the scheme of energy levels conferred from the pump power-induced upconversion characteristics. The temperature-dependent upconversion of GdBiW2O9 phosphors was investigated in detail along with the estimation of the stability and repeatability of the measurement. The obtained sensitivity data for the present materials with the corresponding sensing parameters show their probable outlook in temperature sensing applications.
Employment of silicon-micro-ring resonator and compound-ring architecture for stable and tunable single-longitudinal-mode fiber laser
(2018-09-01)
Hsu, Yung
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Yeh, Chien-Hung
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Cheng, Hao-Yun
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Chang, Yuan-Chia
;
Chow, Chi-Wai
In this work, a wavelength-switchable erbium-doped fiber (EDF) glasses-type compound-ring (GTCR) laser with stable single-longitudinal-mode (SLM) oscillation is proposed and presented. In the experiment, to accomplish wavelength-tunable operation, a silicon-micro-ring-resonator (SiMRR) is utilized inside the ring cavity, when the birefringent loss of EDF laser is adjusted properly. Moreover, the GTCR configuration is proposed to as the mode-filter for suppressing the multi-longitudinal-mode (MLM) to achieve the SLM oscillation. Here, the measured linewidth of output wavelength is 61 kHz. The output stabilities of the proposed SiMRR EDF compound-ring laser are also discussed experimentally. (C) 2018 Elsevier Ltd. All rights reserved.
A Speed- and Power-Efficient SPIHT Design for Wearable Quality-On-Demand ECG Applications
(2018-09-01)
Hsieh, Jui-Hung
;
Hung, King-Chu
;
Lin, Yu-Ling
;
Shih, Meng-Ju
;
生物科技學系
In this paper, a speed and power-efficient set partitioning in hierarchical trees (SPIHT) design is introduced for one-dimensional (1-D) wavelet-based electrocardiography (ECG) compression systems with quality guarantee. To achieve real-time and low-power design objectives toward wearable quality-on-demand (QoD) ECG applications, we first propose a coding-time-and computation-efficient SPIHT algorithm using various types of coding status register files to overcome the disadvantages of low coding speeds and complicated hardware architectures characterizing prior SPIHT algorithms resulting from the necessity of dynamic computation and arrangement in the sorting and refinement processing phase. Second, a highly pipelined and power-efficient very large scale integration (VLSI) architecture is developed to implement a high-performance and low-power SPIHT design based on the proposed algorithm. The final simulation results demonstrate that our proposed algorithm can speed up the average coding time 1.52 to 2.74 times compared to prior work with an identical compression ratio for an 11-level 1024 x 1 1 - D discrete wavelet transform at diverse target percentage root-mean-square differences (PRDT) on various MIT-BIH arrhythmia datasets. Applied to wearable wavelet-based QoD ECG applications, our proposed VLSI architecture attains a working frequency of 740 MHz and consumes an average of 23 mu W of power with Taiwan Semiconductor Manufacturing Company 90-nm CMOS technology, which shows the effectiveness of speed and power over the state-of-the-art designs.
Fundus photography with subpixel registration of correlated laser speckle images
(2018-09-01)
Li, Jie-En
;
Tien, Chung-Hao
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光電工程學系
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Department of Photonics
In this paper, we propose multiple modalities based on laser speckle correlation and image registration to enhance the visibility of the fundus without a scanning interferometric scenario, resulting in robustness against intra frame noises induced by inevitable movement. The experimental results showed, with the features from laser speckle contrast imaging (LSCI), that the quality of images obtained using a conventional imaging system could be enhanced. Moreover, by applying the image registration process, we successfully eliminated the inter frame blurring caused by eye movements in an in vivo experiment. The concept was proven when the image contrast of a vascular feature was improved by 1.00x-2.75x. (c) 2018 The Japan Society of Applied Physics
Shake table tests on RC frame infilled by slitted masonry panels
(2018-09-01)
Yuen, Terry Y. P.
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Zhang, Han-hui
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Kuang, J. S.
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Huang, Qunxian
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土木工程學系
Unreinforced masonry infill walls are widely used as non-structural partitions in RC frames. The effects of infills on the structural responses are often ignored in the design process since they are generally considered as expendable elements. However, recent studies have shown that not only shear damage can be inflicted to the columns braced by the infill walls, but also that the structural stability can be jeopardised by the fall-off of the infills. This paper presents the development of new detailing methods for the infill walls, which features slit panels, isolation gaps between the infills and columns, and anchorage of the infills. The proposed detailing methods were tested and verified experimentally using shake-table tests on five 1/3-scale infilled RC frame specimens with different combinations of the features stated above. The design and construction of the shake-table test specimens have taken into account the similitude requirements. The test results indicate that the proposed detailing method effectively reduced the undesirable interaction between column and infill walls. And the use of proper anchorage could prevent the fall off of infills from the bounding frame. Furthermore, the specimens with slit infill walls displayed better seismic performances, which could be attributed to the rocking behaviour of the sub-panels with increased aspect ratios.
Automatic Optimization of Wayfinding Design
(2018-09-01)
Huang, Haikun
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Lin, Ni-Ching
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Barrett, Lorenzo
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Springer, Darian
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Wang, Hsueh-Cheng
Wayfinding signs play an important role in guiding users to navigate in a virtual environment and in helping pedestrians to find their ways in a real-world architectural site. Conventionally, the wayfinding design of a virtual environment is created manually, so as the wayfinding design of a real-world architectural site. The many possible navigation scenarios, as well as the interplay between signs and human navigation, can make the manual design process overwhelming and non-trivial. As a result, creating a wayfinding design for a typical layout can take months to several years. In this paper, we introduce the Way to Go! approach for automatically generating a wayfinding design for a given layout. The designer simply has to specify some navigation scenarios; our approach will automatically generate an optimized wayfinding design with signs properly placed considering human agents' visibility and possibility of making mistakes during a navigation. We demonstrate the effectiveness of our approach in generating wayfinding designs for different layouts such as a train station, a downtown and a canyon. We evaluate our results by comparing different wayfinding designs and show that our optimized wayfinding design can guide pedestrians to their destinations effectively and efficiently. Our approach can also help the designer visualize the accessibility of a destination from different locations, and correct any "blind zone" with additional signs.
A versatile low-resistance ohmic contact process with ohmic recess and low-temperature annealing for GaN HEMTs
(2018-09-01)
Lin, Yen-Ku
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Bergsten, Johan
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Leong, Hector
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Malmros, Anna
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Chen, Jr-Tai
Deeply recessed ohmic contacts for GaN-based high electron mobility transistors (HEMTs) are demonstrated. It is shown that low-resistance ohmic contacts can be achieved with recessing beyond the AlGaN Schottky barrier where the ohmic contacts are formed on the sidewall of the recess. This makes the process versatile and relatively insensitive to the exact recess depth. The ohmic contact is based on a gold-free metallization scheme consisting of a Ta/Al/Ta metal stack requiring a low-temperature annealing. Important parameters for this type of ohmic contact process include the metal coverage, slope of the etched sidewall, bottom Ta-layer thickness, as well as annealing temperature and duration. The optimized contact resistance is as low as 0.24 Omega mm after annealing at 575 degrees C. Moreover, this sidewall contact approach was successfully implemented on different epitaxial heterostructures with different AlGaN barrier thickness as well as with and without AlN exclusion layer. All the samples exhibited excellent contact resistances in a wide range of recess depths. The Ta-based, sidewall ohmic contact process is a promising method for forming an ohmic contact on a wide range of GaN HEMT epitaxial designs.
The Bland-Altman range of agreement: Exact interval procedure and sample size determination
(2018-09-01)
Jan, Show-Li
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Shieh, Gwowen
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管理科學系
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Department of Management Science
The Bland-Altman analysis has been widely used to assess the agreement between two quantitative methods of measurement. The range of agreement is thus represented by the designated central proportion of the distribution of the paired differences. This article aims to provide concrete guidance on the use of accurate confidence intervals of the range of agreement. Theoretical examination and numerical comparison are conducted to support the exact approach and to demonstrate the disadvantages of the currently suggested methods for confidence interval estimation of the range of agreement. For the purpose of design planning, the associated sample size calculations for precise interval estimation of the range of agreement are delineated under the expected width and assurance probability considerations. To enhance the utility of the recommended confidence interval and sample size procedures in practical applications, both SAS and R computer algorithms are also developed.
Surge protection design with surge-to-digital converter for microelectronic circuits and systems
(2018-09-01)
Chen, Wen-Chieh
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Ker, Ming-Dou
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
A surge protection design with surge-to-digital converter is proposed to provide the surge protection for microelectronic products with more flexible applications. The proposed surge-to-digital converter can transfer the occurrences of the surge events into digital output codes by classifying the voltage levels of surge events. It can be used to avoid unwanted power-on reset action, redundant power consumption, or unexpected soft errors, achieving the stability improvement of microelectronic systems. With this surge-to-digital converter, a surge protection design against a surge test of 25 V can clamp the peak voltage of V-DD from 22.2 V to 5.6 V. The proposed converter has been verified in a 0.18-mu m CMOS process.
非對稱性苯并三（硫族吩）化合物及其合成方法，以及高分子
(2018-09-01)
鄭彥如
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包郁傑
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陳世言
本發明提供一種非對稱性苯并三(硫族吩)化合物及其合成方法，以及高分子。在合成非對稱性苯并三(硫族吩)化合物的過程中，使用四(三苯基膦)鈀催化劑及[1,3-二(2,6-二異丙基苯基)咪唑-2-亞基]氯[3-苯基烯丙基]鈀(II)催化劑進行催化。非對稱性苯并三(硫族吩)化合物中含有以下雜環結構：呋喃、噻吩、硒吩及/或碲吩。
On deviations from free-radial outflow in the inner coma of comet 67P/Churyumov-Gerasimenko
(2018-09-01)
Gerig, S. -B.
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Marschall, R.
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Thomas, N.
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Bertini, I.
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Bodewits, D.
The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) onboard the European Space Agency's Rosetta spacecraft acquired images of comet 67P/Churyumov-Gerasimenko (67P) and its surrounding dust coma starting from May 2014 until September 2016. In this paper we present methods and results from analysis of OSIRIS images regarding the dust outflow in the innermost coma of 67P. The aim is to determine the global dust outflow behaviour and place constraints on physical processes affecting particles in the inner coma. We study the coma region right above the nucleus surface, spanning from the nucleus centre out to a distance of about 50 km comet centric distance (approximately 25 average comet radii). We primarily adopt an approach used by Thomas and Keller (1990) to study the dust outflow. We present the effects on azimuthally-averaged values of the dust reflectance of non-radial flow and non-point-source geometry, acceleration of dust particles, sublimation of icy dust particles after ejection from the surface, dust particle fragmentation, optical depth effects and the influence of gravitationally bound particles. All of these physical processes could modify the observed distribution of light scattered by the dust coma. In the image analysis, profiles of azimuthally averaged dust brightness as a function of impact parameter b (azimuthal average, "(A) over bar -curve") were fitted with a simple function that best fits the shape of our profile curves (f (b; u, v, w, z) = u/b(v) + wb + z). The analytical fit parameters (u, v, w, z), which hold the key information about the dust outflow behaviour, were saved in a comprehensive database. Through statistical analysis of these information, we show that the spatial distribution of dust follows free-radial outflow behaviour (i.e. force-free radial outflow with constant velocity) beyond distances larger than similar to 11.9 km from the comet centre, which corresponds to a relative distance of about 6 average comet radii from the comet centre. Hence, we conclude that beyond this distance, and on average, fragmentation and gravitationally bound particles are negligible processes in determining the optically scattered light distribution in the innermost coma. Closer to the nucleus we observe dust outflow behaviour that deviates from free-radial outflow. A comparison of our result profiles with numerical models using a Direct Simulation Monte Carlo (DSMC) approach with dust particle distributions calculated using a test particle approach has been used to demonstrate the influence of a complex shape and particle acceleration on the azimuthal average profiles. We demonstrate that, while other effects such as fragmentation or sublimation of dust particles cannot be ruled out, acceleration of the dust particles and effects arising from the shape of the irregular nucleus (non-point source geometry) are sufficient to explain the observed dust outflow behaviour from image data analysis. As a by-product of this work, we have calculated "Af rho" values for the 1/r regime. We found a peak in the coma activity in terms of Af rho (normalised to a phase angle of 90) of similar to 210 cm 20 days after perihelion. Furthermore, based on simplified models of particle motion within bound orbits, it is shown that limits on the total cross-sectional area of bound particles might be derived through further analysis. An example is given. (C) 2018 The Authors. Published by Elsevier Inc.
Quantum-Dot Photonic-Crystal Surface-Emitting Lasers with Bottom Distributed Bragg Reflector
(2018-09-01)
Hsu, Ming-Yang
;
Lin, Gray
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Quantum-dot (QD) photonic-crystal (PC) surface-emitting laser (SEL) devices with bottom distributed Bragg reflector (DBR) were fabricated based on vertical-cavity SEL structure with top DBR completely removed. Two-dimensional (2D) PCs were deeply etched through QD multilayers to yield strong diffraction coupling. Room-temperature optically pumped lasing emissions at 1194 nm and 1296 nm were demonstrated for two lattice periods of 360 nm and 395 nm, respectively. Two lasing wavelengths separated over 100 nm; however, there were less than two times difference in threshold power densities while slope efficiencies were comparable. The unique spectral gain characteristics of QDs were considered in interpretation of gain-cavity detuning. Moreover, simulation revealed the sub-cavity should be designed so that its resonant wavelength is in phase with lasing wavelength.
ESTABLISHMENT OF GENE SIGNATURE BIOMARKERS FOR IDENTIFICATION OF LYMPH NODE METASTASIS IN ENDOMETRIAL CANCER PATIENTS
(2018-09-01)
Huang, C. Y.
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Huang, H. D.
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Chang, T. H.
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生物科技學系
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Department of Biological Science and Technology
SUBSIDY EXTINCTION AND THE DISTINCTION BETWEEN COMPANY AND SHAREHOLDERS UNDER THE SCM AGREEMENT: PROPOSING A CONTROL-CENTERED APPROACH
(2018-09-01)
Lo, Chih-yuan
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科技法律學院
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College of Law
The Agreement on Subsidies and Countervailing Measures allows Members to impose countervailing duties on subsidized imports that are causing harm to the relevant domestic industry. To impose Countervailing Duties (hereinafter "CVDs"), Members must establish, among other things, that the producer in question enjoyed a subsidy "benefit" during the time of export. In two privatization cases, US - Lead and Bismuth II and US - Countervailing Measures on Certain EC Products, the Panels and Appellate Body (hereinafter "AB") established a principle that could significantly affect a Member's right to impose CVDs. The principle states that the sale of shares in a company at arm's length and for fair market value presumably extinguishes any subsidy "benefit" previously enjoyed by that company. It follows that the company is no longer deemed to enjoy any subsidy "benefit", therefore, the importing Member will not be able to countervail the company's products. One particularly questionable aspect of the principle's rationale is the complete lack of a distinction between the company and its shareholders. The lack of distinction allowed for the notion that a purchase of shares made by the shareholders could extinguish a subsidy received by the company even though there was no money being taken out of the company. The Panels (and the AB to some extent) in the two privatization cases considered that whether the money taken out of the company is irrelevant, as the company and its shareholders are together a single subsidy "recipient" to be assessed. This paper argues that the Panel and AB's reasoning and assessment of the shareholder-company relationship are flawed and introduces a control-centered approach as a potential alternative.
Resonance and Cancellation in Torsional Vibration of Monosymmetric I-Sections Under Moving Loads
(2018-09-01)
Yang, Y. B.
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Li, Mei
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Zhang, Bin
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Wu, Yuntian
;
Yang, Judy P.
This paper is concerned with the lateral and torsional coupled vibration of monosymmetric I-beams under moving loads. To this end, a train is modeled as two subsystems of eccentric wheel loads of constant intervals to account for the front and rear wheels. By assuming the lateral and torsional displacements to be restrained at the two ends of the beam, both the lateral and torsional displacements are approximated by a series of sine functions. The method of variation of constants is adopted to derive the closed-form solution. For the most severe condition when the last wheel load is acting on the beam, both the conditions of resonance and cancellation are identified. Once the condition of cancellation is enforced, the resonance response can always be suppressed, which represents the optimal design for the beam. Since the condition for suppressing the torsional resonance is exactly the same as that for the vertical resonance, this offers a great advantage in the design of monosymmetric I-beams, as no distinction needs to be made between the suppression of vertical or torsional resonance.
Two-Step Solvent On-Film Annealing (2-SOFA) Method: Fabrication of Anisotropic Polymer Particles and Implications for Colloidal Self-Assembly
(2018-09-01)
Tseng, Hsiao-Fan
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Chiu, Yu-Jing
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Wu, Bo-Hao
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Li, Jia-Wei
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Chen, Jiun-Tai
In recent years, anisotropic polymer particles have gained increased interest owing to their special properties and broader applications, such as drug delivery, optical traps, and e-paper display. Most strategies to produce anisotropic polymer particles, however, require sophisticated instruments or additional surfactants. Here, we develop a simple and versatile method, the two-step solvent on-film annealing (2-SOFA) technique, to make anisotropic polymer particles with different shapes. Polystyrene (PS) microspheres spin-coated on poly(methyl methacrylate) (PMMA) films are chosen as model materials. By sequentially annealing the PS/PMMA composites in different solvent vapors, anisotropic polymer particles with distinctive and diverse shapes can be produced, such as half-eaten-peach-shaped, snowman-shaped, and bowler-hat-shaped morphologies. An exquisite selective removal strategy is applied to check the morphologies of the PS/PMMA composite films and to comprehend the transformation mechanism at different annealing steps and times. For particles merged from multiple microspheres, quantitative studies are also performed to figure out the relationships between the sizes of the merged particles and the numbers of the original microspheres. These results have implications for colloidal self-assembly.
Theoretical Calculations for the 1,4-Hydrogen Shift of 1-Hydroxyallyl Radicals Leading to alpha-Keto Radicals; Prediction of Facilitation by 1-Amino and 3-Tin Substituents
(2018-09-01)
Matsubara, Hiroshi
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Kawamoto, Takuji
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Fukuyama, Takahide
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Ryu, Ilhyong
;
應用化學系
DFT calculations were carried out to elucidate the 1,4-hydrogen shift of 1-hydroxyallyl radicals to give alpha-keto radicals. The 1,4-H shift is predicted to be exothermic with large energy barriers. However, the energy barriers of 1,4-H shift were predicted to be lowered significantly by 1-amino and 3-tin substituents. The results agreed well with the experimental results shown by the stannylcarbonylation of alkynes in the presence of an amine, in which the 1,4-H shift of substituted 1-hydroxyallyl radicals has been proposed as a key step.
Effect of hole blocking dielectric layer on microstructure and photoconducting properties of polycrystalline Se thin films
(2018-09-01)
Chang, Cheng-Yi
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Lin, Yi-Jie
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Huang, Yu-Wei
;
Liao, Jye-Yow
;
Lin, Jian-Siang
We fabricated polycrystalline selenium (c-Se) based photodetectors using three different dielectrics (HfO2, Al2O3 and SiO2) as the hole blocking layer (HBL), and studied the influence of the HBLs on the photoconducting performance of the photodetectors. The microstructure of the c-Se layer is greatly influenced by the nucleation behavior of the tellurium (Te) adhesion layer deposited between the c-Se layer and the HBLs. The photoconducting performance of the photodetectors is basically dependent on the barrier height at the junctions of the HBL with the tin-doped indium oxide (ITO) anode and with the c-Se layer. A higher barrier height at the HBL/ITO junction leads to a lower dark current density (I-D) of the photodetectors. However, the photodetector with the SiO2 HBL exhibits the largest I-D as the bias exceeds 2 V although it has the highest junction barrier height. We attribute the abnormity to the rugged morphology of the c-Se layer, which is a result of a less dense Te nucleation on the SiO2 HBL. The photocurrent density (I-ph) is inversely related to the junction barrier height at the HBL/c-Se contact. The c-Se photodetector with the HfO2 HBL has the largest I-Ph and the one with the SiO2 HBL has the smallest. The photodetector with the HfO2 HBL exhibits a quantum efficiency of 89% at 6 V.