Browsing by Author "Chen, JM"

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A comparison between the Fehrenbacher-Rice and the Liechtenstein-Mazin models
(2000-11-01)
Liu, SJ
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Lin, JY
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Chen, JM
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Nachimuthu, P
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Luo, CW
Unoccupied electronic states of Y1-xPrxCu3O7-y (x = 0 - 1) thin films have been investigated using high-resolution polarization-dependent O K-edge x-ray absorption spectroscopy (XANES). After determining the hole distribution among different oxygen sites of the Pr-doped thin films, we compare the experimental data with the Fehrenbacher and Rice (FR) model and the Liechtenstein and Mazin (LM) model, both of which are based on the hybridization of Pr 4f(z(x2-y2)) and O 2p(pi) orbitals in PrBa2Cu3O7-y. Our experimental results are more consistent with the FR model.
A high-throughput VLSI architecture for LZFG data compression
(2002-03-01)
Chen, JM
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Wei, CH
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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
This paper presents a high-throughput VLSI architecture for LZFG data compression and decompression, To reduce the hardware cost and maintain both of the interior node and the leaf node numbering systems, we modify the original LZFG data structure. Compared to the original LZFG tree, the number of characters in our modified LZFG data structure must be greater than one to establish one new interior node down the root node (<^>) into the new node. Meanwhile, this architecture employs a series of encoding cells with content addressable memory (CAM) to search the longest match and maintain the LZFG data tree during the encoding and decoding processes. By using the parallel design, the compressor and decompressor can keep a constant high bit rate to encode and decode one character per clock cycle, that is, it is directly proportional to the operating clock rate, but independent of the sizes of the word dictionary and the input file. By using 0.25 mum CMOS silicon technology, the operating clock rate can be as high as 85 MHz. Some untargeted encoding cells will be disabled to reduce the power consumption during the comparison operation. Therefore, this architecture can be easily applied in the high-speed real-time communication and data storage systems.
A novel VLSI design for Ziv-Lempel data compression
(1998)
Chen, JM
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Wei, CH
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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
In this paper, we present a simple real-time parallel architecture for CMOS VLSI implementation of Ziv-Lempel (LZ type) data compression system. This encoding system employs a linear systolic array to find concurrently the matches between each input data character and its corresponding dictionary. A new encoding architecture is proposed to improve the encoding speed and reduce the hardware complexity for the encoding cells. The access time of memory is reduced to save its power consumption for high-speed applications. The encoder encodes one character( more than 8 bits)per encoding cycle. The clock rate by Verilog simulator can be constrainted below 12ns by 0.6um CMOS technology process.
A simple dispersion measurement of fiber gratings by interferometric technique
(2006-01-01)
Sheu, LG
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Chen, JM
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Yu, SY
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Hsu, KC
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Tsai, MC
A simple dispersion measurement of fiber gratings using an un-balanced Michelson interferometer is proposed. A broadband source and an optical spectrum analyzer are used to scan the interference spectrum, and then the group time delay can be obtained rapidly by Fourier transform processing the interference spectrum. We measured the group time delays of a uniform-period FBG, a chirped FBG, an arrayed-waveguide grating interleaver, and a thin-film filter type OADM by an un-balanced Michelson and Mach-Zehnder interferometers, respectively. The experimental results excellent match the measured results of the optical network analyzer. The experimental repeatability is shown to be better than 1ps.
Anisotropic electronic structure of in-plane aligned a-axis YBa2Cu3O7-delta thin films
(2003-09-01)
Luo, CW
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Chen, MH
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Liu, SJ
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Wu, KH
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Juang, JY
Polarization-dependent x-ray absorption near-edge spectra (XANES) of the O 1s has been measured on a highly in-plane aligned a-axis YBa2Cu3O7-delta (YBCO) thin film. The in-plane XANES, with the electric field E of the linearly polarized synchrotron light being parallel to the b or c axis of YBCO films (E//b or E//c) were obtained in a normal-incidence alignment. The XANES for E//a was then calculated from the data obtained by varying the angle. The results lend strong support to those obtained by using detwinned YBCO single crystals in all crystalline orientations, including the extrapolated c-axis spectra. (C) 2003 American Institute of Physics.
Anisotropic O 2p-Mn 3d unoccupied states in La1-xMnO3: an X-ray absorption spectroscopy study
(2002-02-01)
Lin, JY
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Chen, CW
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Liu, YC
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Liu, SJ
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Wu, KH
We have studied La1-xMnO3 thin films, which show the metal-insulator transition similar to La1-xCaxMnO3. The transport and magnetic properties are measured, X-ray absorption spectroscopy is employed to investigate the electronic structure. Surprisingly, the electronic structure of La1-xMnO3 shows large anisotropy. Our results suggest that La1-xMnO3 is unique among manganites. (C) 2002 Elsevier Science B.V. All rights reserved.
Charge transfer process in Tl2Ba2Ca2Cu3O10 and Tl2Ba2CaCu2O8 thin films probed by polarized X-ray absorption spectroscopy
(1997-09-26)
Chen, JM
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Liu, RG
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Liu, RS
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Lin, HC
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Uen, TM
We report high-resolution polarized O 1s X-ray absorption spectra of highly c-axis-oriented Tl2Ba2Ca2Cu3O10 (Tl-2223) and Tl2Ba2CaCu2O8 (Tl-2212) superconducting thin films. Near the O Is edge, the low-energy pre-edge peak at 528.3 eV has mainly O 2p(xy) symmetry, while the pre-edge peak at 529.4 eV has predominantly O 2p, character. The spectral weight of the pre-edge peak at 528.3 eV, originating from the CuO2 planes, increases similar to 60% from the Tl-2212 to Tl-2223 thin films. Conversely, the high-energy pre-edge peak at 530.3 eV, originating from the TlO planes, is lower in spectral intensity by similar to 30% in Tl-2223 as compared to the Tl-2212 thin film. The experimental results clearly demonstrate the pictures of the self doping due to the charge transfer from the CuO2 layers to the TlO layers. (C) 1997 Published by Elsevier Science B.V.
Dissociation dynamics of excited neutral fragments of gaseous SiCl4 following Si 2p and Cl 2p core-level excitations
(2005-09-01)
Chen, JM
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Lu, KT
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Lee, JM
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Ho, SC
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Chang, HW
State-specific dissociation dynamics for excited fragments of gaseous SiCl4 following Cl 2p and Si 2p core-level excitations were characterized by the dispersed UV/optical fluorescence spectroscopy. The core-to-Rydberg excitations at both Si 2p and Cl 2p edges lead to a noteworthy production of excited atomic fragments, neutral and ionic (Si-*,Si+*). In particular, the excited neutral atomic fragments Si-* are significantly reinforced. The core-to-valence excitation at the Si 2p edge generates an enhancement of excited molecular-ion SiCl4+. The experimental results provide deeper insight into the dissociation dynamics for excited neutral fragments of molecules via core-level excitation.
Earth pressures with sloping backfill
(1997-03-01)
Fang, YS
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Chen, JM
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Chen, CY
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交大名義發表
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土木工程學系
This paper presents experimental data of earth pressure acting against a vertical rigid wall, which moved away from or toward a mass of dry sand with an inclined surface. The instrumented retaining-wall facility at National Chiao Tung University (NCTU) Taiwan, was used to investigate the variation of earth pressure induced by the translational wall movement. Based on experimental data, it has been found that the earth-pressure distributions are essentially linear at each stage of wall movement. Both the wall movement required for the backfill to reach an active state and the wall movement needed for the backfill to reach a passive state increase with an increasing backfill inclination. The experimental active and passive earth-pressure coefficients for various backfill sloping angles are in good agreement with the values calculated by Coulomb's theory. It may not be appropriate to adopt the Rankine theory to determine either active or passive earth pressure against a rigid wall with sloping backfill.
Earth pressures with sloping backfill - Closure
(1998-11-01)
Fang, YS
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Chen, JM
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Chen, CY
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土木工程學系
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Department of Civil Engineering
Electromigration lifetime improvement of copper interconnect by cap/dielectric interface treatment and geometrical design
(2005-12-01)
Lin, MH
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Lin, YL
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Chen, JM
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Yeh, MS
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Chang, KP
A significant improvement of electromigration (EM) lifetime is achieved by modification of the preclean step before cap-layer deposition and by changing Cu cap/dielectric materials. A possible mechanism for EM lifetime enhancement was proposed. Cu-silicide formation prior to cap-layer deposition and adhesion of Cu/cap interface were found to be the critical factors in controlling Cu electromigration reliability. The adhesion of the Cu/cap interface can be directly correlated to electromigration median-time-to-failure and activation energy. Effects of layout geometrical variation and stress current direction were also investigated.
Electronic structure and transport properties of La0.7Ce0.3MnO3
(2005-10-01)
Chang, WJ
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Tsai, JY
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Jeng, HT
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Lin, JY
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Zhang, KYJ
X-ray absorption spectroscopy (XAS), optical reflectance spectroscopy, and the Hall effect measurements were used to investigate the electronic structure in La0.7Ce0.3MnO3 thin films (LCeMO). The XAS results are consistent with those obtained from LDA+U calculations. In that the doping of Ce has shifted up the Fermi level and resulted in marked shrinkage of hole pockets originally existing in La0.7Ca0.3MnO3 (LCaMO). The Hall measurements indicate that in LCeMO the carriers are still displaying the characteristics of holes as LDA+U calculations predict. Analyses of the optical reflectance spectra evidently disapprove the scenario that the present LCeMO might have been dominated by the La-deficient phases.
Glutathione S-transferase M1*null genotype but not myeloperoxidase promoter G-463A polymorphism is associated with higher susceptibility to endometriosis
(2004-10-01)
Hsieh, YY
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Chang, CC
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Tsai, FJ
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Lin, CC
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Chen, JM
Glutathione S-transferase M1 (GSTM1), one member of the GST family, is responsible for metabolism of xenobiotics and carcinogens. Myeloperoxidase (MPO) plays an important role in the oxidation and activation of carcinogens and nitric oxide. Allelic variants of GSTM1 and MPO gene polymorphisms might impair detoxification function and increase the susceptibility to endometriosis. We aimed to investigate if these polymorphisms are useful markers for predicting endometriosis susceptibility. Women were divided into two groups: (i) endometriosis (n=150); (ii) non-endometriosis (n=159). Polymorphisms for GSTM1 and MPO were amplified by polymerase chain reaction and detected by electrophoresis after restriction digestion. The relative frequencies of the GSTM1*wild (+/+,+/0)/null (0/0) genotypes and MPO-463*G/A gene polymorphisms between both groups were compared. The distribution of GSTM1 polymorphisms was significantly different between the two groups. Proportions of GSTM1*wild/null alleles in both groups were: (i) 36.7/63.3%; (ii) 95/5% (P=0.001). In contrast, MPO-463 genotypes were not significantly different between the two groups. Proportions of MPO*A homozygote/heterozygote/G homozygote in both groups were: (i) 2.7/17.4/79.9% and (ii) 1.9/17/81.1% (P> 0.05). We conclude that the GSTM1*null genotype is associated with a higher risk of endometriosis development. MPO-463*G/A gene polymorphism is not related to the susceptibility of endometriosis.
Hole distribution in YxPr1-xBa2Cu4O8 and YxPr1-xBa2Cu3O7 probed by X-ray absorption spectroscopy
(2004-08-01)
Chen, JM
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Liu, SJ
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Lee, JM
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Lin, JY
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Gou, YS
Utilizing high-resolution O K-edge X-ray absorption spectra, we report a comparative study on the variation of hole states with Pr doping for Y-x Pr1-xBa2Cu3O7 and YxPr1-xBa2 Cu-4 O-8. The depletion rate of hole carriers in the CuO2 planes with Pr doping in YxPr1-xBa2Cu4 O-8 is considerably slower than that in YxPr1-xBa2Cu3O7. The oxygen content affects the depletion rate of hole carriers in cuprates with Pr doping. (C) 2004 Elsevier B.V. All rights reserved.
Hole states of X-Bi2Sr2CaCu2O8 [X=I, HgI2, and (Py-CH3)(2)HgI4] probed by OK-edge X-ray absorption spectroscopy
(2006-01-01)
Chen, JM
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Chang, SC
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Liu, RS
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Lee, JM
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Park, M
Hole states of X-Bi2Sr2CaCU2O8[X-Bi2212, X=I, HgI2, and (Py-CH3)(2)-HgI4, Py = pyridinel have been probed by O K-edge X-ray absorption near-edge structure (XANES) spectra. In the O 1s absorption edge of X-Bi2212, the pre-edge peak at similar to 528.3 eV is attributed to transitions into the 0 2p hole states located in the CuO2 planes. The hole concentration in the CuO2 planes of X-Bi2212 increases for X =I and HgI2, but decreases for X= (Py-CH3)(2)HgI4 as coMPared to pristine Bi2212. The variation of CuO2-plane hole concentration of Bi2212 is primarily responsible for the T-c variation upon intercalation. (c) 2005 Elsevier Ltd. All rights reserved.
Intelligent location tracking strategy in PCS
(2000-02-01)
Wang, K
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Liao, JM
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Chen, JM
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資訊工程學系
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Department of Computer Science
An alternative strategy (AS) for reducing location update signalling load has been proposed to improve the classical strategy (CS) used in the Global System for Mobile Communications (GSM). However, the AS is suitable only for long-term events and fixed movement tracks. Location tracking (paging) costs more when the mobile host (MH) changes movement habits or encounters short-term events. A novel method is proposed that aims to reduce signalling load resulting from location tracking in the above situations. The key idea is to take user recent movement information (called the paging information record) into account to determine which location area to page first. Performance evaluation has been conducted using a city area zone model that can model a realistic city area environment. Experimental results show that the method can reduce location management signalling costs by 14-55% and 6-39% compared to CS and AS, respectively. The overhead of the approach is the additional storage space required (for storing MH profiles and paging information records) and the additional processing time. However, the overhead is insignificant in terms of today's memory capacity and processor speed, and the reduction in signalling load makes more bandwidth available.
Investigation of the electrical properties and reliability of amorphous SiCN
(2004-01-30)
Chen, CW
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Chang, TC
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Liu, PT
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Tsai, TM
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Huang, HC
Amorphous SiCN (a-SiCN) is a candidate for barrier dielectric and has lower dielectric constant (ksimilar to5) relative to the commonly used barrier SiN (ksimilar to7). In this study, we investigate the leaky behavior and barrier characteristics of a-SiCN (k: 4similar to5) doped with different nitrogen concentration. The leaky behavior of a-SiCN is Poole-Frenkel at high electric field. This is similar to SiN. Thermal stability of a-SiCN films is good enough to meet the prescription in back-end-of-line fabrication process. The bias-temperature stress (BTS) test has been conducted on a-SiCN to investigate the barrier ability against copper 15/16penetration. We find that a-SiCN could sustain the stress of electric field up to 4 mV/cm at 150 degreesC. In addition, a-SiCN films with higher nitrogen concentration exhibit better barrier property against copper penetration. The SIMS spectra also have been used to monitor the distributions of copper after different BTS conditions, confirming our inference on leakage mechanism. (C) 2003 Elsevier Science B.V. All rights reserved.
Origin of size effect on superconductivity in (R-0.8 Pr-0.2)Ba2Cu3O7 studied by soft X-ray absorption spectroscopy
(2001-03-30)
Chen, JM
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Nachimuthu, P
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Lin, JY
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Hong, IP
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Chang, CF
O K-edge X-ray absorption near-edge structure (XANES) spectroscopy of (R-0.8 Pr-0.2)Ba2Cu3O7 (R = Y, Tm, Dy, Gd, Eu and Sm) has been performed to investigate the dependence of hole distribution on ionic size of the R3+ ions. Near the O Is absorption edge, pre-peaks at similar to 527.8 and similar to 528.5 eV are assigned to transitions into O 2p hole states located in the CuO3 ribbons and CuO2 planes, respectively. As deduced from O K-edge X-ray absorption spectra, the hole concentrations in the CuO2 planes decrease monotonically with increasing ionic size of the rare-earth elements. The present XANES results clearly demonstrate that the suppression of superconductivity in (R1-x Pr-x)Ba2Cu3O7 With ionic radius of the R3+ ions results predominantly from the hole-depletion effect. (C) 2001 Elsevier Science B.V. All rights reserved.
Peculiar hole doping by Ca substitution in cuprate superconductors
(2003-05-01)
Lin, JY
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Chung, PC
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Liu, SJ
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Hsiang, CC
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Lin, PH
The doping effect of Ca substitution in Y0.7Ca0.3Ba2Cu3Oy has been studied for y=6.9 and 6 by the x-ray absorption near edge spectroscopy (XANES). While Ca doping leads to an obvious increase in hole concentration in the CuO2 planes in Y0.7Ca0.3Ba2Cu3O6.9, XANES indicates absence of this doping effect in Y0.7Ca6.3Ba2Cu3O6. These two contradict results suggest that the doping effect by Ca substitution could be sensitive to the oxygen content when y similar to6.0. Comparisons with others' works are made.
Polarization-dependent X-ray absorption spectroscopy of in-plane aligned (100) YBa2Cu3O7-delta thin films
(2003-05-01)
Luo, CW
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Liu, SJ
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Chen, MH
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Wu, KH
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Lin, JY
Polarization-dependent X-ray absorption spectra (XAS) on the 0 Is edge has been measured on a highly in-plane aligned (100) a-axis YBa2Cu3O7-delta (YBCO) thin films. The in-plane XAS, that is, the electric field E of the linearly polarized synchrotron light parallels to b- or c-axes of YBCO films (Eparallel tob or Eparallel toc), were obtained in a normal-incidence alignment. Furthermore, the XAS for Eparallel toa was calculated from the oblique incidence to the sample with different angles. The present results are consistent with those obtained by using detwinned YBCO single crystals. (C) 2003 Elsevier Science B.V. All rights reserved.