Browsing by Issue Date, starting with "2007-05-25"

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Dissociation of energy-selected CH3CN+ in a region 15.1-16.5 eV: Vibrationally enhanced dissociation and mechanisms
(2007-05-25)
Huang, Chuan-Keng
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Lin, I.-Feng
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Chiang, Su-Yu
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應用化學系
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Department of Applied Chemistry
Threshold photoelectron-photoion coincidence spectra of CH3CN were measured in a region 15.1-16.5 eV. We observed a small vibrational enhancement on dissociation of CH3CN+ and obtained kinetic energy releases for channels C2HN+ + H-2 and CH2+ + HCN. The kinetic energies released in channel C2HN+ + H-2 are substantial; a linearly extrapolated dissociation threshold of 14.68 +/- 0.01 eV agrees with a Gaussian-3 B3LYP prediction 14.70 eV for formation of HCCN+ + H-2. In contrast, the small releases for channel CH2+ + HCN agree with a statistical calculation. We describe a plausible dissociation mechanism with the Gaussian-3 B3LYP method to rationalize experimental results. (c) 2007 Elsevier B.V. All rights reserved.
Contact to ZnO and intrinsic resistances of individual ZnO nanowires with a circular cross section
(2007-05-28)
Lin, Yen-Fu
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Jian, Wen-Bin
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Wang, C. P.
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Suen, Yuen-Wuu
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Wu, Zhong-Yi
Single crystalline ZnO nanowires (NWs) with a circular cross section and similar to 40 nm in diameter have been synthesized and utilized to fabricate two-contact ZnO NW devices. The electrical properties of the NW devices can be categorized into two classes according to the magnitude of their room-temperature resistances. I-V curves of low-resistance devices exhibit downward bending features and their temperature dependent resistances demonstrate thermal activation transport in the ZnO NWs. The high-resistance NW devices can be modeled as back-to-back Schottky contacts and the electron transport through the contacts reveals a variable-range-hopping mechanism. (C) 2007 American Institute of Physics.
Quantum limit of optimum four-level ASK signals with direct detection optically preamplified receivers
(2007-05-28)
Peng, Wei-Ren
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Chi, Sien
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光電工程學系
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Department of Photonics
We analytically obtain the exact fundamental limit of 4- level amplitude shifted keying formats (4ASK) with direct detection optically preamplified receivers. The optimum multilevel spacing and the corresponding decision thresholds, which depend both on the signal to noise ratio and optical bandwidth, are obtained numerically considering the Chis-quared distribution of each level. The quantum limit under the optimum level spacing is 127.5 photons/bit, which is about 0.2 dB smaller than the results by the Gaussian approximation. Over a broad range of the signal to noise ratio and the optical bandwidth, we have found that not only the bit error rate but also the optimum level spacing are well predicted by Gaussian method, although the three decision thresholds are all underestimated. (C) 2007 Optical Society of America.
Near-infrared femtosecond laser crystallized poly-Si thin film transistors
(2007-05-28)
Wang, Yi-Chao
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Shieh, Jia-Min
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Zan, Hsiao-Wen
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Pan, Ci-Ling
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光電工程學系
Polycrystalline silicon (poly-Si) thin film transistors (TFTs) fabricated by near-infrared femtosecond laser annealing (FLA) are demonstrated. The FLA-annealed poly-Si channels exhibit low tail-state, deep-state, and midgap-state densities of grain traps. Characteristics such as field-effect mobility, threshold voltage, and subthreshold slope for FLA-annealed poly-TFTs are comparable to those of conventional approaches. A wide process window for annealing laser fluences was confirmed by examining the changes in electrical parameters for transistors with various channel dimensions. (C) 2006 Optical Society of America.
Effects of supercritical CO2 fluid on sputter-deposited hafnium oxide
(2007-05-28)
Liu, Po-Tsun
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Tsai, Chih-Tsung
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Yang, Po-Yu
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光電工程學系
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顯示科技研究所
Low-temperature supercritical fluid (SCF) technology is employed to improve the dielectric characteristics of metal oxide film deposited at low temperature. In this investigation, hafnium oxide (HfO2) film was sputter deposited at room temperature and post-treated with SCF at 150 degrees C, replacing typical high-temperature annealing process. From Fourier transformation infrared and thermal desorption spectroscopy measurement, the absorption peaks of Hf-O-Hf bonding and the oxygen content in HfO2 film have, respectively, shown apparent raise. The leakage current density of the low-temperature deposited HfO2 film is reduced significantly, and the conduction mechanism is modified from trap-assisted quantum tunneling to thermionic emission process, since SCF treatment effectively reduces the number of traps in HfO2 film. (C) 2007 American Institute of Physics.
Nickel nanocrystals with HfO2 blocking oxide for nonvolatile memory application
(2007-05-28)
Yang, F. M.
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Chang, T. C.
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Liu, P. T.
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Chen, U. S.
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Yeh, P. H.
A distributed charge storage with Ni nanocrystals embedded in the SiO2 and HfO2 layer has been fabricated in this study. The mean size and aerial density of the Ni nanocrystals are estimated to be about 5 nm and 3.9x10(12)/cm(2), respectively. The nonvolatile memory device with Ni nanocrystals exhibits 1 V threshold voltage shift under 4 V write operation. The device has a long retention time with a small charge lose rate. Besides, the endurance of the memory device is not degraded up to 10(6) write/erase cycles. (C) 2007 American Institute of Physics.
Operations of poly-Si nanowire thin-film transistors with a multiple-gated configuration
(2007-05-30)
Su, C. J.
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Lin, H. C.
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Tsai, H. H.
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Hsu, H. H.
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Wang, T. M.
In this study, a novel multiple-gated (MG) thin-film transistor (TFT) with poly-Si nanowire ( NW) channels is fabricated using a simple process flow. In the proposed new transistors, poly-Si NWs were formed in a self-aligned manner and were precisely positioned with respect to the source/drain, and the side-gate. Moreover, the NW channels are surrounded by three gates, i.e., top-gate, side-gate and bottom-gate, resulting in much stronger gate controllability over the NW channels, and greatly enhanced device performance over the conventional single-gated TFTs. Furthermore, the independently applied top-gate and/or bottom-gate biases could be utilized to adjust the threshold voltage of NW channels in a reliable manner, making the scheme suitable for practical applications.
Device and method for integrating sound effect processing and active noise control
(2007-05-31)
Bai, Mingsian R.
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Ou, Kuen-Ying
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Lin, Jain-Liang
A device and a method for integrating 3D sound effect processing and active noise control are proposed. A digital signal processor incorporates an artificial reverberator and a 3D spatial audio processor into an audio module. The audio signal is presented via an earphone. Next, a microphone embedded in the vicinity of the loudspeaker inside the headset is used to sense an external noise while playing, and feed it back to an active noise controller, which generates an anti-noise to eliminate the external noise. Therefore, the signal to noise ratio can be increased and the 3D sound field effect can be significantly enhanced. In addition, a head-related transfer function is more efficiently implemented on the basis of an interaural transfer function in the spatial audio processing to reduce the filter order lower and hence the computation loading.
Method and apparatus for telephone routing between PTN and PSTN
(2007-05-31)
Chang, Ming-Feng
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Lin, Yi-Bing
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Liang, Ching-Feng
Disclosed is a method and apparatus applicable to an interface between PSTN and PTN for telephone routing. The interface includes a branch switch, a key system, a network branch switch, and media gateway, etc. The telephone routing method and apparatus of the present invention creates, maintains, and utilizes a call-back routing table to enable a specified PSTN user to call the callback external leased line to reach a specified PTN user in a one-stage dialing manner. The process of one-stage dialing includes PTN call origination to PSTN, PSTN call origination to PTN, and callback tag insertion in the call-back routing table. The call-back routing table consists of a plurality of call-back tags. Each call-back tag consists of at least a data triple, i.e. PTN user identifier, PSTN called party telephone number, and callback leased line identifier.
Vertical-channel organic thin-film transistors with meshed electrode and low leakage current
(2007-06-01)
Zan, Hsiao-Wen
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Yen, Kuo-Hsi
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光電工程學系
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顯示科技研究所
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Department of Photonics
In this study, we have successfully fabricated vertical-channel organic thin-film transistors with a channel length smaller than 100nm. It is found that Fowler-Nordheim tunneling is the dominant mechanism determining the ultra short-channel device behavior. To improve the gate control capability, a meshed source electrode pad had been used. This significantly lowers the gate and drain driving voltages (<10V), improves the saturation characteristics and reduces the leakage current. The improvement may be due to the fringing field around the source electrode, which suppresses the tunneling effect.
Chaos in a modified van der Pol system and in its fractional order systenis
(2007-06-01)
Ge, Zheng-Ming
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Zhang, An-Ray
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機械工程學系
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Department of Mechanical Engineering
Chaos in a modified van der Pot system and in its fractional order systems is studied in this paper. It is found that chaos exists both in the system and in the fractional order systems with order from 1.8 down to 0.8 much less than the number of states of the system, two. By phase portraits, Poincare maps and bifurcation diagrams, the chaotic behaviors of fractional order modified van der Pot systems are presented. (c) 2005 Elsevier Ltd. All rights reserved.
Universal share for the sharing of multiple images
(2007-06-01)
Fang, Wen-Pinn
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Lin, Ja-Chen
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資訊工程學系
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Department of Computer Science
To share numerous grey-valued images (or numerous color-valued images), this study presents a system with a universal share. A company organizer can use this universal share to attend the recovery meeting of any shared image. No storage space is wasted; i.e. for each shared image, the total storage space occupied by all generated shares (including the universal share) is identical to the image size.
Magneto-electrodynamical modeling and design of a microspeaker used for mobile phones with considerations of diaphragm corrugation and air closures
(2007-06-01)
Chao, Paul C. -P.
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Chiu, Chi-Wei
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Hsu-Pang, Yuan
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電控工程研究所
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Institute of Electrical and Control Engineering
Recent design trends for modern mobile phones are evolving to be miniaturized and versatile sounds in quality. To these ends, a microspeaker with a corrugated diaphragm is employed to broaden the sound frequency range. Due to the fact that diaphragm corrugation and air closures were not considered in any past studies, this study presents comprehensive modeling with the consideration of diaphragm corrugations and air closures. It starts with the modeling on the subsystems of the voice coil motor (VCM) in the speaker. The magnetic field of the VCM is modeled by one set of finite elements, while the corrugated diaphragm is modeled by another set of finite elements. In addition, the air closures above or below the diaphragm are modeled by the third group of finite elements based on basic acoustics. Simulations are conducted with and without air closures. It is found that: 1) the speaker with 45 degrees corrugation exhibits overall higher (better) sound pressure levels (SPLs), while 2) the 75 degrees corrugation leads to unsatisfied, low SPLs below 1 kHz and two undesired antiresonances at higher frequencies. The theoretical findings are successfully validated by experiments.
AlGaInAs quantum-well as a saturable absorber in a diode-pumped passively Q-switched solid-state laser
(2007-06-01)
Huang, S. C.
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Liu, S. C.
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Li, A.
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Su, K. W.
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Chen, Y. F.
We demonstrate what is believed to be the first use of AlGaInAs quantum wells (QWs) as a saturable absorber in the Q switching of a high-power diode-pumped Nd-doped 1.06 mu m laser. The barrier layers are designed to locate the QW groups in the region of the nodes of the lasing standing wave to avoid damage. With an incident pump power of 13.5 W, an average output power of 3.5 W with a Q-switched pulse width of 0.9 ns at a pulse repetition rate of 110 kHz was obtained. (c) 2007 Optical Society of America.
Robust environmental change detection using PTZ camera via spatial-temporal probabilistic modeling
(2007-06-01)
Hu, Jwu-Sheng
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Su, Tzung-Min
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper proposes a novel procedure for detecting environmental changes by using a pan-tilt-zoom (PTZ) camera. Conventional approaches based on pixel space and stationary cameras need time-consuming image registration to yield pixel statistics. This work proposes an alternative approach to describe each scene with a Gaussian mixture model (GMM) via a spatial-temporal statistical method. Although details of the environment covered by the camera are lost; this model is efficient and robust in recognizing scene and detecting scene changes in the environment. Moreover, the threshold selection for separating different environmental changes is convenient by using the proposed framework. The effectiveness of the proposed method is demonstrated experimentally in an office environment.
Preparation of UV-curable intercalated/exfoliated epoxide/acrylateclays nanocomposite resins
(2007-06-01)
Wang, Yu-Young
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Hsieh, Tsung-Eong
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材料科學與工程學系
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Department of Materials Science and Engineering
Preparation of UV-curable intercalated/exfoliated epoxide/acrylateclays nanocomposite resins with the addition of specific monomers and solvent via the consideration of solubility parameter and chemical reactivity was carried out in this work. Due to the good compatibility with surfactant in acrylateclays and the cationic oligorner in resin matrix, the two additive monomers dispersed uniformly in resin matrix with the swollen acrylateclays before UV curing. As revealed by conversion ratio and DTG analyses, chemical bonds between the two additive monomers, the cationic oligomers and surfactant in acrylateclays were formed during UV irradiation. This, in turn, generated a hybrid acrylate-based/epoxy network and effectively enlarged the lamellae spacing of inorganic clays in nanocomposite resins prepared in this work. The XRD and TEM characterizations revealed that the intercalated clay domains containing exfoliated lamellae about 1 nm in thickness uniformly disperse in polymeric matrix. The nanocomposite resin containing 5 wt.% inorganic filler possessed the physical properties as follows: Td-5% = 213 degrees C, CTE = 80.5 ppm/degrees C, moisture absorption = 6.12%, average optical transmittance = 83.17%, and adhesion strength on glass substrate = 43.8 kgf/cm(2). The analyses above indicated that the formation of polymeric interpenetrating networks and nanometer-scale exfoliation of clay lamellae not only improve the thermal properties and resistance to moisture permeation, but also retain highly optical transmittance and satisfactory adhesion strength of nanocomposite resins prepared in this work. A better device lifetime property was hence achieved when the nanocomposite resins were applied to the packaging of OLEDs.
Investigating the value of information sharing in multi-echelon supply chains
(2007-06-01)
Chen, Mu-Chen
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Yang, Taho
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Yen, Chi-Tsung
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
Under the structure of multiple business entities, supply chain management (SCM) offers the external and internal integration of business processes in enterprises. The most important objective of SCM is to enhance the supply chain performance such as reinforcing the service level and increasing profit as well as reducing order cycle time and inventory. In recent years, due to the advancement of information technology, enterprises can manage the product flow and the information flow via economical and efficient mechanisms. The well-organized information sharing can enhance the supply chain performance and allow enterprises to refine their strategies of supply chain in order to maximize their profits. The previous studies pointed out the positive effect of information sharing on the efficiency of supply chain. However, relatively little literature focuses on the performance analysis for multi-echelon supply chain with various information sharing scenarios. By using the simulation technique, this paper models different scenarios of information sharing, and further analyzes the impacts of information quality on multi-echelon supply chain performance. In addition, this paper employs Data Envelopment Analysis (DEA) to integrate multiple performance measures to ensure the information sharing scenarios with enhanced performance.
A hybrid fuzzy-optimization approach to customer grouping-based logistics distribution operations
(2007-06-01)
Sheu, Jiuh-Biing
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
This paper presents an integrated fuzzy-optimization customer grouping based logistics distribution methodology for quickly responding to a variety of customer demands. The proposed methodology involves three main mechanisms: (1) pre-route customer classification using fuzzy clustering techniques, (2) determination of customer group-based delivery service priority and (3) en-route goods delivery using multi-objective optimization programming methods. In the process of pre-route customer classification, the proposed method groups customers' orders primarily based on the multiple attributes of customer demands, rather than by static geographic attributes, which are mainly considered in classical vehicle routing algorithms. Numerical studies including a real-world application are conducted to illustrate the applicability of the proposed method and its potential advantages over existing operational strategies. Using the proposed method, it is shown that the overall performance of a logistics distribution system can be improved by more than 20%, according to the numerical results from the case studied. (c) 2006 Elsevier Inc. All rights reserved.
An efficient code generation algorithm for non-orthogonal DSP architecture
(2007-06-01)
Lee, Yi-Hsuan
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Chen, Cheng
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資訊工程學系
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Department of Computer Science
To meet strict speed and power requirements for embedded applications, many high-end digital Signal Processors (DSPs) commonly employ non-orthogonal architectures that are typically characterized by irregular data paths, heterogeneous registers, and multiple memory banks. Obviously to harvest the benefits provided by this non-orthogonal architecture sufficient compiler support is necessary and important. However, the complexity of such architectures presents a great challenge to compiler design and the usual compilation techniques for general-purpose CPUs do not adapt well to the irregularity of DSP. The entire code generation process must include the following phases: intermediate representation, code compaction, instruction scheduling, memory bank assignment (or variable partition), and register/accumulator assignment. Much related research only considers some phases, which is inadequate. In this paper, we present an effective code generation algorithm named Rotation Scheduling with Spill Codes Predicting (RSSP) to maximally exploit the benefits of non-orthogonal architectures. It contains six parts that cover almost the entire phases of the code generation process. As well as introducing the detailed principles and algorithms of the proposed RSSP, we use an analytic model to evaluate its preliminary performance. Evaluation results clearly demonstrate the effectiveness of the proposed method. Furthermore, we also present some preliminary ideas to generalize RSSP, which can make it more practicable and suit various DSPs with similar architectural features.
A note on parallel-machine scheduling with deteriorating jobs
(2007-06-01)
Jeng, A. A. K.
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Lin, B. M. T.
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資訊工程學系
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資訊管理與財務金融系註：原資管所+財金所
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Department of Computer Science
We consider a parallel-machine scheduling problem of minimizing the total completion time. The processing time of a job is a linear function of its starting time and deterioration rate. This problem is known to be NP-hard, even for the case with two machines. In this note, we generalize an existing lower bound for the two-machine case to the general case with an arbitrary number of machines. Despite the generalization concerning machine number, our bound has one extra term that makes our bound tighter than the existing one.