Browsing by Issue Date, starting with "2002-08-01"

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A novel amplifying antenna array using patch-antenna couplers - Design and measurement
(2002-08-01)
Tsai, CH
;
Yang, YCA
;
Chung, SJ
;
Chang, K
;
電信工程研究所
This paper proposes a novel amplifying antenna array using the patch-antenna coupler formed by placing one or two open-ended microstrip lines (coupled lines) near and along the nonradiating edge(s) of a patch antenna. An X-band five-element array with broadside 25-dB Chebyshev radiation is demonstrated. When the input signal is fed to the center element, with most of the power radiating from the antenna, part of it is tapped to the coupled lines, amplified by an FET amplifier, and fed to the next antenna element. This process is repeated after all the antenna elements are fed with suitable power. The amplitude distribution of the fields radiated from the antennas is controlled by the coupling coefficient from the patch to the coupled line, which, in turn, is governed by the coupling length and gap between the patch and line. The measured return loss of the designed five-element array is -27 dB at the center frequency of 10 GHz with 2% 10-dB bandwidth. The radiation pattern possesses a transmitting gain of 15.9 dB, a half-power beamwidth of 17degrees, and a sidelobe level of -22 dB.
Analysis of petroleum distillates from fire debris using supercritical fluid extraction with a two-level orthogonal array experimental design
(2002-08-01)
Huang, CT
;
Hsieh, YZ
;
應用化學系
;
Department of Applied Chemistry
A supercritical fluid extraction (SFE) method was developed in the present study as an effective sample pretreatment technique of petroleum distillates from fire debris. Three petroleum distillates were used as target analytes, including 95 unleaded gasoline, kerosene, and premium diesel. An orthogonal array (L16) experimental design was adopted to separately evaluate primary SFE experimental factors. The SFE efficiencies of petroleum distillates at various extraction conditions were examined and the optimized SFE conditions were identified. Experimental results demonstrated that the optimized SFE method not only provided an effective extraction method for the spiked sample, but also successfully recovered residues of petroleum distillates from fire debris.
Dependence of deep level concentrations on ammonia flow rate in n-type GaN films
(2002-08-01)
Lee, L
;
Chang, FC
;
Chung, HM
;
Lee, MC
;
Chen, WH
Deep level transient spectroscoppy was used to characterize the deep levels of GaN films grown with various V/III ratios using metalorganic vapor phase epitaxy. Two prominent defects, located at E(C)-0.569 +/- 0.003 and E(C)-1.013 +/- 0.091 eV, were detected in this study. When the NH(3) flow rate was increased, we observed a slight increase in trap concentration of the E(C)-0.569 eV defect and a significant increase at E(C)-1.013 eV. Although a high V/III seems necessary for obtaining good quality GaN film, our results indicate that, if the ammonia is in excessive supply, it may generate a large number of E(C)-1.013 eV deep level defects, which deteriorate the film quality - which should be avoided with special care.
A manufacturer's optimal quantity discount strategy and return policy through game-theoretic approach
(2002-08-01)
Su, CT
;
Shi, CS
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This study generalised the traditional quantity discount problem with return contracts, in which a manufacturer promises to refund some fraction of the retailer's wholesale price if an item is returned, as a two-stage game. In the first stage the manufacturer and retailer determine the inventory level cooperatively. In the second stage, the manufacturer bargains with the retailer for quantity discount and return schemes to maintain channel efficiency. A menu of discount-return combinations is proposed for the manufacturer to make inventory decisions. The model developed will demonstrate that the return policy can be considered as mirror images of quantity discount strategy. That is, options with more generous return privileges are coupled with higher wholesale prices, whereas the lowest wholesale price comes with very strict limits on returns and a restocking fee for any returned goods.
A fast audio bit allocation technique based on a linear R-D model
(2002-08-01)
Lee, CY
;
Fang, YC
;
Chuang, HC
;
Wang, CN
;
Chiang, T
The MPEG-1 Layer III audio coding is most widespread digital audio format on the Internet. Its encoder is more complicated than the other layers., in the MPEG-I audio specification, where the bit allocation constitutes significant part of the total computational load. This paper describes a fast bit allocation technique using a novel linear model to compute the bitrate and the global gain of the inner loop (rate control loop) for the classic MP3 bit allocation problem. Estimated quantization noise is approximated with a binomial expansion for the adjustment of the scalefactors. This procedure reduces the outer loop iterations (distortion control loop) to one loop. Our bit allocation technique is about five times faster compared to the well-known LAME MP3 encoder. Based on the objective quality measure, total number of distorted bands, and average total noise-to-masking ratio (NMR), our experimental results show that there is significant improvement in speedup of the encoding process without noticeable audio quality degradation.
Electron energy state spin-splitting in 3D cylindrical semiconductor quantum dots
(2002-08-01)
Li, Y
;
Voskoboynikov
;
Lee, CP
;
Sze, SM
;
Tretyak, O
In this article we study the impact of the spin-orbit interaction on the electron quantum confinement for narrow gap semiconductor quantum dots. The model formulation includes: (1) the effective one-band Hamiltonian approximation; (2) the position- and energy-dependent quasi-particle effective mass approximation; (3) the finite hard wall confinement potential; and (4) the spin-dependent Ben Daniel-Duke boundary conditions. The Hartree-Fock approximation is also utilized for evaluating the characteristics of a two-electron quantum dot system. In our calculation, we describe the spin-orbit interaction which comes from both the spin-dependent boundary conditions and the Rashba term (for two-electron quantum dot system). It can significantly modify the electron energy spectrum for InAs semiconductor quantum dots built in the GaAs matrix. The energy state spin-splitting is strongly dependent on the dot size and reaches an experimentally measurable magnitude for relatively small dots. In addition, we have found the Coulomb interaction and the spin-splitting are suppressed in quantum dots with small height.
A parallelized indexing method for large-scale case-based reasoning
(2002-08-01)
Chen, WC
;
Tseng, SS
;
Chang, LP
;
Hong, TP
;
Jiang, MF
Case-based reasoning (CBR) is a problem-solving methodology commonly seen in artificial intelligence. It can correctly take advantage of the situations and methods in former cases to find out suitable solutions for new problems. CBR must accurately retrieve similar prior cases for getting a good performance. In the past, many researchers proposed useful technologies to handle this problem. However, the performance of retrieving similar cases may be greatly influenced by the number of cases. In this paper, the performance issue of large-scale CBR is discussed and a parallelized indexing architecture is then proposed for efficiently retrieving similar cases in large-scale CBR. Several algorithms for implementing the proposed architecture are also described. Some experiments are made and the results show the efficiency of the proposed method. (C) 2002 Elsevier Science Ltd. All rights reserved.
Precursor ISI-free frame synchronization for DMT VDSL system
(2002-08-01)
Lin, ST
;
Wei, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new modified maximum likelihood (ML) algorithm for frame synchronization in discrete multitone VDSL transmission system is presented. Computer simulation results are included to show its improvement in Et/N-0 of each tone in the received data. This algorithm estimates the frame boundary at the initial transition edge rather than at the middle peak of a shortened twisted-pair channel response. The timing margin degradation caused by precursor intersymbol interference (ISI) can be reduced significantly, especially at the sub-channel loaded with more bits.
Impacts of gate structure on dynamic threshold SOI nMOSFETs
(2002-08-01)
Lo, WC
;
Chang, SJ
;
Chang, CY
;
Chao, TS
;
電子工程學系及電子研究所
The effects of different substrate-contact structures (T-gate and H-gate) dynamic threshold voltage silicon-on-insulator (SOI) nMOSFETs (DTMOS) have been investigated. It is found that H-gate structure devices have higher driving current than T-gate under DTMOS-mode operation. This is because H-gate SOI devices have larger body effect factor (gamma), inducing a lager reduction of threshold voltage. Besides, it is found that drain-induced-barrier-lowering (DIBL) is dramatically reduced for both T-gate and H-gate structure devices when devices are operated under DTMOS-mode.
Investigation of superfilling and electrical characteristics in low-impurity-incorporated Cu metallization
(2002-08-01)
Shieh, JM
;
Chang, SC
;
Dai, BT
;
Feng, MS
;
材料科學與工程學系
Complete filling of 0.13-mum vias and deposition of Cu with a low resistivity of about 2.3 muOmega(.)cm were obtained using an electrolyte with 2-aminobenzothiazole (2ABT) as the filling promoter. Due to the moderate charge transfer polarization characteristic realized by the addition of 2ABT, the film resistivity and the activation energy for thermal grain growth were similar to those for electrolytes without it. After rapid thermal annealing (RTA) at 400degreesC for 30 s, the resistivity was further reduced to similar to1.9 muOmega(.)cm.
A solution model of integrating cells of PCS to switches in wireless ATM network
(2002-08-01)
Din, DR
;
Tseng, SS
;
資訊工程學系
;
Department of Computer Science
In this paper, we investigate the optimal assignment problem of cells in PCS (Personal Communication Service) to switches on a ATM (Asynchronous Transfer Mode) network. Given cells and switches on an ATM network (whose locations are fixed and known), the problem is to group cells into clusters and assign these clusters to switches in an optimum manner. This problem is modeled as a complex integer programming problem. Since finding an optimal solution of this problem is NP-hard, a heuristic solution model consists of three phases (Cell Pre-Partitioning Phase, Cell Exchanging Phase, and Cell Migrating Phase) is proposed. Experimental results show that Cell Exchanging and Cell Migrating Phases can really reduce total cost near 44% on average.
Smith form of FIR pseudocirculants
(2002-08-01)
Lin, YP
;
Phoong, SM
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The pseudocirculant matrices have been found to be a very useful tool in the analysis and design of communication systems, e.g., precoding systems and discrete multitone transceivers. In these systems, a scalar channel P(z) is recast into a pseudocirculant channel matrix. Many important channel properties have been derived from the Smith form and the decomposition of pseudocirculants. In this letter, we will show that the Smith form of a pseudocirculant matrix can be given in terms of the zeros of the underlying finite-impulse response (FIR) channel P(z). Once the zeros of P(z) are known, the Smith form of the corresponding pseudocirculant matrix can be obtained in closed form.
Study on dopant activation of phosphorous implanted polycrystalline silicon thin films by KrF excimer laser annealing
(2002-08-01)
Tseng, CH
;
Lin, CW
;
Teng, TH
;
Chang, TK
;
Cheng, HC
The KrF excimer laser annealing of phosphorous implanted polycrystalline silicon (poly-Si) films had been investigated completely. Resistors were fabricated to measure sheet resistance of poly-Si film. The interference effect, heat absorption of capping oxide as well as transformation of poly-Si grain size during laser annealing were reported. Depending on the carrier concentrations, poly-Si exhibits different sheet resistance behavior when the excimer laser fluence is higher than the full-melt threshold fluence. The sheet resistance of poly-Si film has an abnormal increase from 5 x 10(4) to 4 x 10(6) Q/square when the excimer laser energy is higher than full-melt threshold energy. (C) 2002 Elsevier Science Ltd. All rights reserved.
A compact low-power rail-to-rail class-B buffer for LCD column driver
(2002-08-01)
Weng, MC
;
Wu, JC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper proposes a compact, low-power, and rail-to-rail class-B output buffer for driving the large column line capacitance of LCDs. The comparator used as a nonlinear element in feedback path is modified from the current-mirror amplifier, which has area and power advantages. The output buffer was realized in a 0.35 mum CMOS process. The active area of the buffer is 86 X 73.5 mum(2). With a 3.3 V supply, the measured quiescent current is 7.4 muA. The settling time for 0.05-3.25 V swing to within 0.2% is 8 mus.
管管作品三首
(2002-08-01)
管管
Impact of nitrogen and/or fluorine implantation on deep-submicron Co-salicide process
(2002-08-01)
Chang, TY
;
Lei, TF
;
Chao, TS
;
Chen, SW
;
Kao, LM
In our previous study, using NF3 annealed poly-Si to improve gate oxide integrity for Co-silicide process has been proposed [SSDM, 1998, p. 164]. It is very interesting and important to know the mechanism of both F and N incorporation in the SiO2 and Co-salicide. In this study, F and/or N will be implanted into poly-Si with/without Co-salicide process, to identify the interaction of N and F in the SiO2 and Co-salicide process. In our work, we will describe the optimized structure and F/N incorporation for Co-silicide process. (C) 2002 Elsevier Science Ltd. All rights reserved.
Syntheses of nano-sized cubic phase early transition metal carbides from metal chlorides and n-butyllithiurn
(2002-08-01)
Chang, YH
;
Chin, CW
;
Chen, YC
;
Wu, CC
;
Tsai, CP
Nano-sized early transition metal carbides, including TiC, ZrC, HfC, V4C3, NbC and TaC, were synthesized from colloidal precursors generated by reducing the metal chlorides, TiCl4, ZrCl4, HfCl4, VCl3, NbCl5, and TaCl5, respectively, with n-C4H9Li in hexane. The colloids were formed from the reduction of the metal centers, which then nucleated into nano-scaled metal clusters. The major byproducts were LiCl, C4H10, and C4H8, indicating that the butyl groups probably underwent beta-hydrogen elimination and reductive elimination. This suggests that C-C bond activation of the butyl groups was in operation, leaving residual carbon atoms in the metal colloids. The colloids were further heated at 873-1273 K to crystallize into cubic phase TIC, ZrC, HfC, V4C3, NbC and TaC nanoparticles.
H-infinity tracking-based sliding mode control for uncertain nonlinear systems via an adaptive fuzzy-neural approach
(2002-08-01)
Wang, WY
;
Chan, ML
;
Hsu, CCJ
;
Lee, TT
;
電控工程研究所
In this paper, a novel adaptive fuzzy-neural sliding mode controller with H-infinity tracking performance for uncertain nonlinear systems is proposed to attenuate the effects caused by unmodeled dynamics, disturbances and approximate errors. Because of the advantages of fuzzy-neural systems, which can uniformly approximate nonlinear continuous functions to arbitrary accuracy, adaptive fuzzy-neural control theory is then employed to derive the update laws for approximating the uncertain nonlinear functions of the dynamical system. Furthermore, the H-infinity tracking design technique and the sliding mode control method are incorporated into the adaptive fuzzy-neural control scheme so that the derived controller is robust with respect to unmodeled dynamics, disturbances and approximate errors. Compared with conventional methods, the proposed approach not only assures closed-loop stability, but also guarantees an H-infinity tracking performance for the overall system based on a much relaxed assumption without prior knowledge on the upper bound of the lumped uncertainties. Simulation results have demonstrated that the effect of the lumped uncertainties on tracking error is efficiently attenuated, and chattering of the control input is significantly reduced by using the proposed approach.
A novel all-binary motion estimation (ABME) with optimized hardware architectures
(2002-08-01)
Luo, JH
;
Wang, CN
;
Chiang, TH
;
資訊科學與工程研究所
;
電子工程學系及電子研究所
We present a fast motion estimation algorithm using only binary representation, which is desirable for both embedded system and hardware implementation with parallel architectures. The key algorithm distinction is that only the high-frequency spectrum is used. Our experimental results show that it provides excellent performance at both low and high bit rates. Because of its binary-only representation, the proposed algorithm offers low computational complexity and low memory bandwidth consumption. For multimedia-embedded system design, we further investigated specific implementation techniques for several well-known hardware platforms including Intel x86 processors, single-instruction multiple-data processors, and systolic array circuit design. The systolic array architecture requires only single memory access for both the reference and current frames from the on-chip memory. Such an implementation provides an optimized solution with great throughput, while the quality is maintained. Finally, we show that our binarization methods are closely coupled to the accuracy of binary motion estimation algorithms. The binarization and coding efficiencies can be improved using various filters and binarization methods.
Implementing compensation capacitor in logic CMOS processes
(2002-08-01)
Lin, TC
;
Wu, JC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
MOSFETs can be used as capacitors, but its capacitance can vary by 5 to 7 times as its terminal voltage varies. To reduce the voltage dependence of the capacitance, this paper proposed two types of devices: one is called accumulation MOSFET (AMOS) and the other is formed by two conventional PMOS connected in anti-parallel. These two devices are readily available in the standard digital CMOS processes. The proposed capacitors were implemented in three different CMOS processes. The measured results show that the capacitances of both devices have less voltage dependence than a single PMOS. The voltage dependence of the AMOS capacitance can be as small as 17%. The minimum capacitance per unit area of the AMOS is 1.8 times that of the double-poly capacitor in an analog/mixed-mode CMOS process. To verify the usefulness of these two types of capacitors, they are used as compensation capacitors in a conventional two-stage amplifier. The measured results show that the amplifier compensated by the AMOS capacitor has little variation (6%) of the unity-gain frequency over the input common-mode range. Due to its smaller die area and cheaper digital process, AMOS can be used as compensation capacitor without resorting to more expensive analog process.