Browsing by Issue Date, starting with "2009-05-01"

Now showing 1 - 20 of 50886

單端多埠之儲存裝置
(2009-05-01)
楊皓義
;
黃威
本發明係有關於一種單端多埠之儲存裝置,其藉由一第一反相器之第一輸入端耦接於一第二反相器之第二輸出端,第一反相器之第一輸出端耦接於第二反相器之第二輸入端,一均衡器,耦接該第一反相器與該第二反相器,以控制該第一反相器與該第二相器之電位,使耦接於第一反相器與於第二反相器之複數存取埠可存取資料。如此,可降低資料寫入儲存裝置所消耗的功率,並加快資料寫入儲存裝置的速度。
The Inductance Enhancement Study of Spiral Inductor Using Ni-AAO Nanocomposite Core
(2009-05-01)
Hsu, M. C.
;
Chao, T. Y.
;
Cheng, Y. T.
;
Liu, C. M.
;
Chen, C.
The letter presents the fabrication and characterization of on-chip spiral inductors with Ni-anodic alumina oxide (Ni-AAO) nanocomposite core. Ni nanorods with 70 nm diameter are deposited and isolated in an AAO matrix to form a layer of nanocomposite on silicon substrate. About 3% inductance enhancement to the inductor with the nanocomposite core has been observed and the enhancement can be kept up more than 6 GHz. Because the proposed inductance enhancement scheme using ferromagnetic-AAO-based nanocomposite as inductor core employs a CMOS-compatible fabrication process with the characteristics that can be further improved, it is our belief that the scheme has a great potential application for future radio frequency integrated circuitry (RFIC) manufacture.
Asymptotic Critical Transmission Radii for Greedy Forward Routing in Wireless Ad Hoc Networks
(2009-05-01)
Wan, Peng-Jun
;
Yi, Chih-Wei
;
Wang, Lixin
;
Yao, Frances
;
Jia, Xiaohua
In wireless ad hoe networks, greedy forward routing is a localized geographic routing algorithm in which one node discards a packet if none of its neighbors is closer to the destination of the packet than itself, or otherwise forwards the packet to the neighbor closest to the destination. If all nodes have the same transmission radii, the critical transmission radius for greedy forward routing is the smallest transmission radius which ensures packets can be delivered by greedy forward routing through any source-destination pair. In this paper, we study asymptotic critical transmission radii of randomly deployed wireless ad hoc networks. Assume network nodes are represented by a Poisson point process of density n over a unit-area convex compact region whose boundary curvature is bounded. We show that the ratio of critical transmission radii to root ln n/pi n is asymptotically almost surely equal to root 1/(2/3 - root 3/2 pi) approximate to 1.6.
Er-Yb Codoped Ferroelectrics for Controlling Visible Upconversion Emissions
(2009-05-01)
Huang, Tung-Ching
;
Hsieh, Wen-Feng
;
光電工程學系
;
Department of Photonics
Under a 980 nm laser pumping, quenching of green upconversion (UC) emission accompanied with enhancement of red UC emission observed was dominated by the energy back-transfer (EBT) process in Er(3+) and Yb(3+) codoped PbTiO(3), BaTiO(3), and SrTiO(3) polycrystalline powders. The efficiency of the EBT process depends not only on Yb(3+) concentration but also on level match of the doped Er(3+) and Yb(3+) ions caused by the crystal fields with different symmetries. Our UC emission spectra and X-ray diffraction confirm that the centrosymmetric crystal field arising from reducing tetragonality causes level match of transition (4)S(3/2) -> (4) I(13/2) of Er(3+) and (2)F(7/2) -> (2) F(5/2) of Yb(3+). This level match is responsible for enhancing red UC emission.
Location Classification of Nonstationary Sound Sources Using Binaural Room Distribution Patterns
(2009-05-01)
Hu, Jwu-Sheng
;
Liu, Wei-Han
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper discusses the relationships between the nonstationarity of sound sources and the distribution patterns of interaural phase differences (IPDs) and interaural level differences (ILDs) based on short-term frequency analysis. The amplitude variation of nonstationary sound sources is modeled by the exponent of polynomials from the concept of moving pole model. According to the model, the sufficient condition for utilizing the distribution patterns of IPDs and ILDs to localize a nonstationary sound source is suggested and the phenomena of multiple peaks in the distribution pattern can be explained. Simulation is performed to interpret the relation between the distribution patterns of IPD and ILD and the nonstationary sound source. Furthermore, a Gaussian-mixture binaural room distribution model (GMBRDM) is proposed to model distribution patterns of IPDs and ILDs for nonstationary sound source location classification. The effectiveness and performance of the proposed GMBRDM are demonstrated by experimental results.
Effect of Pulsed Electromagnetic Field on the Proliferation and Differentiation Potential of Human Bone Marrow Mesenchymal Stem Cells
(2009-05-01)
Sun, Li-Yi
;
Hsieh, Dean-Kuo
;
Yu, Tzai-Chiu
;
Chiu, Hsien-Tai
;
Lu, Sheng-Fen
Pulsed electromagnetic fields (PEMFs) have been used clinically to slow down osteoporosis and accelerate the healing of bone fractures for many years. The aim of this study is to investigate the effect of PEMFs on the proliferation and differentiation potential of human bone marrow mesenchymal stem cells (BMMSC). PEMF stimulus was administered to BMMSCs for 8 h per day during culture period. The PEMF applied consisted of 4.5 ms bursts repeating at 15 Hz, and each burst contained 20 Pulses. Results showed that about 59% and 40% more viable BMMSC cells were obtained in the 2 PEMF-exposed Cultures at 24 h after plating for the seeding density of 1000 and 3000 cells/cm(2) respectively. Although, based on the kinetic analysis, the growth rates of BMMSC during the exponential growth phase were not significantly affected, 20-60% higher cell densities were achieved during the exponentially expanding stage. Many newly divided cells appeared from 12 to 16 h after the PEMF treatment as revealed by the cell cycle analysis. These results Suggest that PEMF exposure Could enhance the BMMSC cell proliferation during the exponential phase and it possibly resulted from the shortening of the lag phase. In addition, according to the cytochemical and immunofluorescence analysis performed, the PEMF-exposed BMMSC showed multi-lineage differentiation potential similar to the control group. Bioelectromagnetics 30:251-260, 2009. (C) 2009 Wiley-Liss. Inc.
Effect of bump size on current density and temperature distributions in flip-chip solder joints
(2009-05-01)
Kuan, Wei-Chih
;
Liang, S. W.
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Three dimensional thermo-electrical analysis was employed to simulate the current density and temperature distributions for eutectic SnAg solder bumps with shrinkage bump sizes. It was found that the current crowding effects in the solder were reduced significantly for smaller solder joints. Hot-spot temperatures and thermal gradient were increased upon reducing the solder. The maximum temperature for solder joint with 144.7 mu m bump height is 103.15 degrees C which is only 3.15 degrees C higher than the substrate temperature due to joule heating effect. However, upon reducing the bump height to 28.9 mu m, the maximum temperature in the solder increased to 181.26 degrees C. Serious joule heating effect was found when the solder joints shrink. The higher Joule heating effect in smaller solder joints may be attributed to two reasons, first the increase in resistance of the Al trace, which is the main heating source. Second, the average and local current densities increased in smaller bumps, causing higher temperature increase in the smaller solder bumps. (C) 2009 Published by Elsevier Ltd.
Signal Remodulation of OFDM-QAM for Long Reach Carrier Distributed Passive Optical Networks
(2009-05-01)
Chow, C. W.
;
Yeh, C. H.
;
Wang, C. H.
;
Shih, F. Y.
;
Chi, S.
The passive optical network (PON) using orthogonal frequency-division multiplexing (OFDM) is a subject of many research works recently. The OFDM signal is especially good for long reach (LR)-PON due to its high tolerance to chromatic dispersion and high spectral efficiency. We study, for the first time, the possibility of using OFDM for signal remodulation in LR-PONs. Three different colorless optical networking unit (ONU) architectures, electroabsorption modulator-based, reflective semiconductor optical amplifier-based, and injection-locked Fabry-Perot laser diode-based ONUs, are tested and compared. Error-free operations are achieved in 100-km fiber transmission without dispersion compensation.
A green supplier selection model for high-tech industry
(2009-05-01)
Lee, Amy H. I.
;
Kang, He-Yau
;
Hsu, Chang-Fu
;
Hung, Hsiao-Chu
;
工業工程與管理學系
With growing worldwide awareness of environmental protection, green production has become an important issue for almost every manufacturer and will determine the sustainability of a manufacturer in the long term. A performance evaluation system for green suppliers thus is necessary to determine the suitability of suppliers to cooperate with the firm. While the works on the evaluation and/or selection of suppliers are abundant, those that concern environmental issues are rather limited. Therefore, in this study, a model for evaluating green suppliers is proposed. The Delphi method is applied first to differentiate the criteria for evaluating traditional suppliers and green suppliers. A hierarchy is constructed next to help evaluate the importance of the selected criteria and the performance of green suppliers. Since experts may not identify the importance of factors clearly, the results of questionnaires may be biased. To consider the vagueness of experts' opinions, the fuzzy extended analytic hierarchy process is exploited. With the proposed model, manufacturers can have a better understanding of the capabilities that a green Supplier must possess and can evaluate and select the most suitable green supplier for cooperation. (C) 2008 Elsevier Ltd. All rights reserved.
Dynamic Characteristics and Linewidth Enhancement Factor of Quantum-Dot Vertical-Cavity Surface-Emitting Lasers
(2009-05-01)
Peng, Peng-Chun
;
Lin, Gray
;
Kuo, Hao-Chung
;
Yeh, Chao-En
;
Liu, Jui-Nung
This study explores the relative intensity noise characteristics of quantum-dot vertical-cavity surface-emitting lasers (QD VCSELs). The resonance frequency and eye diagram are presented. The linewidth enhancement factor (alpha factor) of QD VCSEL is also investigated experimentally. The values of alpha factor were measured to be between 0.48 and 0.60. Moreover, a photonic RF phase shifter is examined using the QD VCSEL. A phase shifter with a total phase shift of 2 pi was demonstrated. These investigations and demonstrations will be useful in the field of QD VCSEL.
Development of GaN-Based Vertical-Cavity Surface-Emitting Lasers
(2009-05-01)
Lu, Tien-Chang
;
Chen, Jun-Rong
;
Chen, Shih-Wei
;
Kuo, Hao-Chung
;
Kuo, Chien-Cheng
This paper reviews the fabrication technology and performance characteristics of optically pumped and electrically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs). The lasing action of optically pumped hybrid GaN-based VCSELs has been observed at room temperature due to the employment of high-quality and high-reflectivity AlN/GaN-based distributed Bragg reflectors in the VCSEL structure. Based on the device structure of the optically pumped hybrid GaN-based VCSELs, we further achieved the lasing action of electrically pumped GaN-based VCSELs under continuous-wave operation at 77 K. The laser has a threshold injection current of 1.4 mA and emits a blue wavelength at 462 nm together with a narrow linewidth of about 0.15 nm. The laser beam has a divergence angle of about 11.7 degrees with a polarization ratio of 80%. A very strong spontaneous coupling efficiency of 7.5 x 10(-2) was measured.
Learning a Scene Background Model via Classification
(2009-05-01)
Lin, Horng-Horng
;
Liu, Tyng-Luh
;
Chuang, Jen-Hui
;
資訊工程學系
;
Department of Computer Science
Learning to efficiently construct a scene background model is crucial for tracking techniques relying on background subtraction. Our proposed method is motivated by criteria leading to what a general and reasonable background model should be, and realized by a practical classification technique. Specifically, we consider a two-level approximation scheme that elegantly combines the bottom-up and top-down information for deriving a background model in real time. The key idea of our approach is simple but effective: If a classifier can be used to determine which image blocks are part of the background, its outcomes can help to carry out appropriate blockwise updates in learning such a model. The quality of the solution is further improved by global validations of the local updates to maintain the interblock consistency. And a complete background model can then be obtained based on a measurement of model completion. To demonstrate the effectiveness of our method, various experimental results and comparisons are included.
A Low-Power and High-Precision Spread Spectrum Clock Generator for Serial Advanced Technology Attachment Applications Using Two-Point Modulation
(2009-05-01)
Kao, Yao-Huang
;
Hsieh, Yi-Bin
;
傳播研究所
;
Institute of Communication Studies
A new technique utilizing two-point (TP) modulation for a spread spectrum clock generator (SSCG) for serial advanced technology attachment is presented in which the divider ratio is varied by a digital Sigma Delta modulator, and the voltage-controlled oscillator is modulated analogically. With this technique, the modulation bandwidth is enhanced in order that the modulation profile accuracy and jitter performance caused by the Sigma Delta modulator can be improved at the same time. The order of the Sigma Delta modulator and the loop filter can be reduced to save power and area, while the electromagnetic interference (EMI) suppression still satisfies specifications. The dual-path loop filter (DL) reduces the size of the loop capacitor and enables full integration. The proposed TPDL-SSCG has been fabricated in a 0.18-mu m CMOS process. The size of the chip area is 0.44 x 0.48 mm(2). The circuit produces a clock of 1.5 GHz with a down-modulation ratio of 0.5%, 10.14 dB EMI of reduction, 5.485 ps rms jitter, and 35 ps peak-to-peak jitter. The power consumption, excluding an output buffer, is only 15.3 mW.
Temperature-dependent X-ray absorption near edge spectroscopy of doped LaMnO(3): Ion-size and the Jahn-Teller distortion effects
(2009-05-01)
Tsai, Y. T.
;
Chang, W. J.
;
Huang, S. W.
;
Lin, J. -Y.
;
Lee, J. Y.
The temperature-dependent X-ray absorption near-edge spectroscopy (XANES) of LaMnO(3) thin films doped with various divalent ions was systematically carried out to investigate the effects of the ion size and associated Jahn-Teller distortions (JTDs) on the electronic structure modifications. Doped LaMnO(3) thin films were grown on (100) SrTiO(3) and (110) NdGaO(3) substrates by pulsed-laser deposition with typical thickness of 250-300 nm. Temperature-dependent resistivity p(T) and magnetization M(T) were measured. The results indicate that the drastic changes in magneto-transport properties induced by the substitution of A-site ion and the splitting of the O K-edge pre-edge peak associated with the e(g)(up arrow) and t(2g)(down arrow) energy levels at low temperatures in La(1-x)Ca(x)MnO(3) and La(1-x)Sr(x)MnO(3) (x = 0.3, 0.375) may both relate to the lattice disorder and the associated JTD effects on modifying the electronic structure of doped-LaMnO(3). (C) 2009 Elsevier B.V. All rights reserved.
Precise orbit determination for the FORMOSAT-3/COSMIC satellite mission using GPS
(2009-05-01)
Hwang, Cheinway
;
Tseng, Tzu-Pang
;
Lin, Tingjung
;
Svehla, Drazen
;
Schreiner, Bill
The joint Taiwan-US mission FORMOSAT-3/ COSMIC (COSMIC) was launched on April 17, 2006. Each of the six satellites is equipped with two POD antennas. The orbits of the six satellites are determined from GPS data using zero-difference carrier-phase measurements by the reduced dynamic and kinematic methods. The effects of satellite center of mass (COM) variation, satellite attitude, GPS antenna phase center variation (PCV), and cable delay difference on the COSMIC orbit determination are studied. Nominal attitudes estimated from satellite state vectors deliver a better orbit accuracy when compared to observed attitude. Numerical tests show that the COSMIC COM must be precisely calibrated in order not to corrupt orbit determination. Based on the analyses of the 5 and 6-h orbit overlaps of two 30-h arcs, orbit accuracies from the reduced dynamic and kinematic solutions are nearly identical and are at the 2-3 cm level. The mean RMS difference between the orbits from this paper and those from UCAR (near real-time) and WHU (post-processed) is about 10 cm, which is largely due to different uses of GPS ephemerides, high-rate GPS clocks and force models. The kinematic orbits of COSMIC are expected to be used for recovery of temporal variations in the gravity field.
Chaos control and anticontrol of a tachometer system by Ge-Yao-Chen partial region stability theory
(2009-05-01)
Ge, Z-M
;
Chiang, C-Y
;
機械工程學系
;
Department of Mechanical Engineering
In this paper, chaos control and anticontrol of a tachometer system by Ge-Yao-Chen (GYC) partial region stability are proposed. The Lyapunov function becomes a simple linear homogeneous function and the controllers become simpler by using the GYC partial region stability theory. The simulation results are more precise because the controllers are in lower degree than that of traditional controllers. Finally, chaos control and anticontrol of the tachometer system by GYC partial region stability are obtained and verified by numerical simulations.
Discrete-Dopant-Induced Timing Fluctuation and Suppression in Nanoscale CMOS Circuit
(2009-05-01)
Li, Yiming
;
Hwang, Chih-Hong
;
Li, Tien-Yeh
;
電信工程研究所
;
Institute of Communications Engineering
As the dimensions of semiconductor devices continue to be reduced, device fluctuations have become critical to determining the accuracy of timing in circuits and systems. This brief studies the discrete-dopant-induced timing characteristic fluctuations in 16-nm-gate complementary metal-oxide-semiconductor (CMOS) circuits using a 3-D "atomistic" coupled device-circuit simulation. The accuracy of the simulation has been confirmed by using the experimentally calibrated transistor physical model. For a 1.6-nm-gate CMOS inverter, 3.5%, 2.4%, 18.3%, and 13.2% normalized fluctuations in the rise time, fall time, high-to-low delay time, and low-to-high delay time, respectively, are found. Random dopants may cause significant timing fluctuations in the studied circuits. Suppression approaches that are based on the circuit and device design viewpoints are implemented to examine the associated characteristic fluctuations. The use of shunted transistors in the circuit provides similar suppression to the use of a device with doubled width. However, both approaches increase the chip area. To eliminate the need to increase the chip area, channel engineering approaches (vertical and lateral) are proposed, and their effectiveness in reducing the timing fluctuation is demonstrated.
Improving Light Output Power of the GaN-Based Vertical-Injection Light-Emitting Diodes by Mg(+) Implanted Current Blocking Layer
(2009-05-01)
Tsai, Min-An
;
Yu, Peichen
;
Chen, J. R.
;
Huang, J. K.
;
Chiu, C. H.
A method for forming a current blocking layer (CBL) by ion implantation in GaN-based vertical-injection light-emitting diodes (VI-LEDs) was proposed. It was found that the use of CBL in VI-LEDs can effectively reduce the current crowding effect and enhance the light output power. The uniform emission intensity distribution of VI-LEDs with CBL was demonstrated by electroluminescence measurements. Experimental results show that the wall-plug efficiency was enhanced by 12.3% at an injection current of 20 mA, compared to that of VI-LEDs without CBL, and by 56.2% compared to that of conventional LEDs. The device simulation results reveal that the current path can be blocked by CBL, resulting in high light extraction efficiencies and large current densities within the effective emission region of active layers.
A scenario-based stochastic programming model for the control or dummy wafers downgrading problem
(2009-05-01)
Chung, Shu-Hsing
;
Yang, Yi-Shu
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
The subject of this paper is to Study a realistic planning environment in wafer fabrication for the control or dummy (C/D) wafers problem with uncertain demand. The demand of each product is assumed with a geometric Brownian motion and approximated by a finite discrete set of scenarios. A two-stage stochastic programming model is developed based oil scenarios and solved by a deterministic equivalent large linear programming model. The model explicitly considers the objective to minimize the total cost of C/D wafers. A real-world example is given to illustrate the practicality of a stochastic approach. The results are better in comparison with deterministic linear programming by using expectation instead of stochastic demands. The model improved the performance of control and dummy wafers management and the flexibility of determining the downgrading policy. Copyright (C) 2008 John Wiley & Sons, Ltd.
Emotion-based music recommendation by affinity discovery from film music
(2009-05-01)
Shan, Man-Kwan
;
Kuo, Fang-Fei
;
Chiang, Meng-Fen
;
Lee, Suh-Yin
;
資訊工程學系
With the growth of digital music, the development of music recommendation is helpful for users to pick desirable music pieces from a huge repository of music. The existing music recommendation approaches are based on a user's preference on music. However, sometimes, it might better meet users' requirement to recommend music pieces according to emotions. In this paper, we propose a novel framework for emotion-based music recommendation. The core of the recommendation framework is the construction of the music emotion model by affinity discovery from film music, which plays an important role in conveying emotions in film. We investigate the music feature extraction and propose the Music Affinity Graph and Music Affinity Graph-Plus algorithms for the construction of music emotion model. Experimental result shows the proposed emotion-based music recommendation achieves 85% accuracy in average. (C) 2008 Elsevier Ltd. All rights reserved.