Browsing by Issue Date, starting with "2009-02-05"

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OPERATING METHOD APPLIED TO LOW DENSITY PARITY CHECK (LDPC) DECODER AND CIRCUIT THEREOF
(2009-02-05)
LIU, Chih-Hao
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Liao, Yen-Chin
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Lee, Chen-Yi
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Chang, Hsie-Chia
;
Hsu, Yarsun
An operating method applied to low density parity check (LDPC) decoders and the circuit thereof are proposed, in which original bit nodes are incorporated into check nodes for simultaneous operation. The bit node messages are generated according to the different between the newly generated check messages and the previously check node messages. The bit node messages can be updated immediately, and the decoder throughput can be improved. In the other way, the required memory of LDPC decoders can be effectively reduced, and the decoding speed can also be enhanced.
Improved reliability of Mo nanocrystal memory with ammonia plasma treatment
(2009-02-09)
Lin, Chao-Cheng
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Chang, Ting-Chang
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Tu, Chun-Hao
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Chen, Wei-Ren
;
Hu, Chih-Wei
We investigated ammonia plasma treatment influence on the nonvolatile memory characteristics of the charge storage layer composed of Mo nanocrystals embedded in nonstoichiometry oxide (SiO(x)). X-ray photoelectron spectra analyses revealed that nitrogen was incorporated into the charge storage layer. Electric analyses indicated that the memory window was reduced and the retention and the endurance improved after the treatment. The reduction in the memory window and the improvement in retention were interpreted in terms of the nitrogen passivation of traps in the oxide around Mo nanocrystals. The robust endurance characteristic was attributed the improvement of the quality of the surrounding oxide by nitrogen passivation.
Size-dependent strain relaxation in InN islands grown on GaN by metalorganic chemical vapor deposition
(2009-02-09)
Tsai, Wen-Che
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Lin, Feng-Yi
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Ke, Wen-Cheng
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Lu, Shu-Kai
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Cheng, Shun-Jen
We report Raman measurements on InN islands grown on GaN by metalorganic chemical vapor deposition. The Raman frequency of the InN E(2) mode is found to decrease exponentially with the island's aspect ratio, indicating a size dependent strain relaxation during the island formation. Our results suggest that most of the strain at the InN-GaN interface have been released plastically during the initial stage of island formations. After that, the residual strain of only -3.5x10(-3) is further relaxed elastically via surface islanding. The experimental data are in agreement with the strain relaxation predicted from a simplified model analysis as well as three-dimensional finite-element simulations.
NiSiGe nanocrystals for nonvolatile memory devices
(2009-02-09)
Hu, Chih-Wei
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Chang, Ting-
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Tu, Chun-Hao
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Chiang, Cheng-Neng
;
Lin, Chao-Cheng
In this work, charge-storage characteristics of NiSiGe nanocrystal memory device have been studied. Transmission electron microscope shows that the annealed NiSiGe film has higher nanocrystal size and density distribution. Related material analyses such as x-ray photoelectron spectroscopy, Raman spectroscopy, and energy dispersive spectrometer were used to confirm that the Ge elements provide the additional nucleation centers and enhance the nanocrystals aggregation during thermal process. With the improved nanocrystal formation process, a remarkable improvement of the memory effect is observed by comparing the NiSi and NiSiGe nanocrystals. In addition, the retention characteristics of the nanocrystals memory devices have been discussed.
New Host Containing Bipolar Carrier Transport Moiety for High-Efficiency Electrophosphorescence at Low Voltages
(2009-02-09)
Gao, Zhi Qiang
;
Luo, Meiming
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Sun, Xiao Hua
;
Tam, Hoi Lam
;
Wong, Man Shing
A new host material for use in phosphorescent OLEDs with desirable electronic properties has been synthesized. The material exhibits superior carrier-transport properties, a narrow optical band gap, relatively high triplet energy, and high thermal stability. It is synthesized by integrating hole-transporting carbazole groups into an electron-transporting phenanthroline core (see figure), and is demonstrated to be an excellent host for phosphorescent dopant emitters.
Large vacuum Rabi splitting in ZnO-based hybrid microcavities observed at room temperature
(2009-02-09)
Chen, Jun-Rong
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Lu, Tien-Chang
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Wu, Yung-Chi
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Lin, Shiang-Chi
;
Liu, Wei-Rein
Wide-band gap ZnO semiconductors are attractive materials for the investigation of microcavity exciton polaritons due to the large exciton binding energy and oscillator strength. We report the growth and characterization of bulk ZnO-based hybrid microcavity. The phenomenon of strong exciton-photon coupling at room temperature has been observed in the ZnO-based hybrid microcavity structure, which consists of 30 pair epitaxially grown AlN/AlGaN distributed Bragg reflector (DBR) on the bottom side of the 3/2 lambda thick ZnO cavity and 9 pair SiO(2)/HfO(2) DBR as the top mirror. The cavity quality factor is about 221. The experimental results show good agreement with theoretically calculated exciton-polariton dispersion curves based on transfer matrix method. From the theoretical and experimental exciton-polariton dispersion curves with two different cavity-exciton detuning values, the large vacuum Rabi splitting is estimated to be about 58 meV in the ZnO-based hybrid microcavity.
Lithium Ion Intercalation Performance of Porous Laminal Titanium Dioxides Synthesized by Sol-Gel Process
(2009-02-10)
Tsai, Min-Chiao
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Chang, Jian-Chia
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Sheu, Hwo-Shuenn
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Chiu, Hsin-Tien
;
Lee, Chi-Young
We have synthesized novel mesoporous titanate nanosheets by reacting titanium isopropoxide (TTIP) with formic acid. The porous nanosheets were characterized as a new titanate structure with intercalation of formate groups and protons, in the form of HCOOH-intercalated titanate. Most interestingly, TiO(2)-B, a well-known but unusual titanium dioxide phase with great potential in applications in Li-ion batteries, was obtained after the nanosheets were heated above 250 degrees C. Mesoporous nanosheets of HCOOH-intercalated titanate, titanium dioxide with mostly TiO(2)-B and titanium dioxide with traces of TiO(2)-B were obtained by heating the as prepared mesoporous titanate nanosheets at 200, 300, and 550 degrees C, respectively. The method reported here is the first to utilize the sol-gel process to synthesize TiO(2)-B. In addition, different anodes were made from HCOOH-intercalated titanate and titanium dioxide with different ratios of TiO2-B to examine the performance of the charging/discharging capacity in Li ion intercalation. The discharging capacity of titanium dioxide with major TiO2-B can reach 357 mA h/g at the first charging cycle and is highest among TiO(2)-B reports so far.
Different effects of probiotic species/strains on infections in preschool children: A double-blind, randomized, controlled study
(2009-02-11)
Lin, Jun-Song
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Chiu, Yi-Han
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Lin, Nien-Tsung
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Chu, Chia-Hsiang
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Huang, Kuo-Chin
Treatment and prevention of pediatric infectious diseases of three commercial probiotic products were evaluated by a double-blind, randomized, controlled trial. Test subjects under age 5,1062 in total, were distributed randomly into four groups. This investigation showed that L. casei rhamnosus can control bacterial, viral and respiratory infections; a multi-species probiotic reduced gastrointestinal disease significantly. Long-term consumption of L. rhamnosus T cell-1 decreased the incidence of bacterial infection. (C) 2008 Elsevier Ltd. All rights reserved.
Single-electron effects in non-overlapped multiple-gate silicon-on-insulator metal-oxide-semiconductor field-effect transistors
(2009-02-11)
Lee, W.
;
Su, P.
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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 systematically presents controlled single-electron effects in multiple- gate silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) with various gate lengths, fin widths, gate bias and temperature. Our study indicates that using the non-overlapped gate to source/drain structure as an approach to the single-electron transistor (SET) in MOSFETs is promising. Combining the advantage of gate control and the constriction of high source/drain resistances, single-electron effects are further enhanced using the multiple- gate architecture. From the presented results, downsizing multiple- gate SOI MOSFETs is needed for future room-temperature SET applications. Besides, the tunnel barriers and access resistances may need to be further optimized. Since the Coulomb blockade oscillation can be achieved in state-of-the-art complementary metal-oxide-semiconductor (CMOS) devices, it is beneficial to build SETs in low-power CMOS circuits for ultra-high-density purposes.
Highest Urgency First (HUF): A latency and modulation aware bandwidth allocation algorithm for WiMAX base stations
(2009-02-12)
Lin, Yi-Neng
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Lin, Ying-Dar
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Lai, Yuan-Cheng
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Wu, Che-Wen
;
交大名義發表
The mobile WiMAX systems based on IEEE 802.16e-2005 provide high data rate for mobile wireless networks. However, the link quality is frequently unstable owing to mobility and air interference and therefore impacts the latency requirement of real-time applications. In the WiMAX standard, the modulation/coding scheme and the boundary of uplink/downlink sub-frames could be adjusted subject to channel quality and the traffic volume, respectively. This provides us a chance to design a MAC-layer uplink/downlink bandwidth allocation algorithm that is QoS/PHY-aware. This work takes into account the adaptive modulation and coding scheme (MCS), uplink and downlink traffic volume, and QoS parameters of all five defined service classes to design a bandwidth allocation algorithm that calculates the slot allocation in two phases. The first phase decides the boundary of uplink and downlink sub-frames by satisfying requests with pending latency violation and proportionating according to traffic volume, while the second phase allocates slots to mobile stations considering urgency, priority and fairness. Simulation results show our algorithm achieves zero latency violation and higher system throughput compared to existing non-QoS/PHY-aware or less-QOS/PHY-aware approaches. (C) 2008 Elsevier B.V. All rights reserved.
Increasing wide-area download throughputs on the roads by trunking multiple cellular channels over a vehicular ad hoc network
(2009-02-12)
Wang, S. Y.
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Chou, C. L.
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Lin, C. C.
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資訊工程學系
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Department of Computer Science
To obtain infotainment services (e.g., traffic, maps, accidents, weather, etc.) on the roads, vehicle drivers and back-seat passengers may want to use wide-area networks (e.g., GPRS) to download useful information from the Internet when needed. In this paper. we design and implement a scheme to increase GPRS download throughput for a vehicle user while he (she) is moving on the roads. This scheme integrates inter-vehicle communication with trunking mechanisms to achieve this goal. This scheme can be readily deployed for any real-world GPRS network or any 3G network without any support from the network operator. Our field trial results show that when this scheme is applied in a motorcade of four vehicles and all of the GPRS channel provided by each vehicle are used to download a file simultaneously, the download speed is 3.92 times faster than that achieved when only one GPRS channel is used. (C) 2008 Elsevier B.V. All rights reserved.
Thermally or Magnetically Induced Polarization Reversal in the Multiferroic CoCr2O4
(2009-02-13)
Choi, Y. J.
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Okamoto, J.
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Huang, D. J.
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Chao, K. S.
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Lin, H. J.
We report the unexpected evolution, with thermal and magnetic-field (H) variations, of the interrelation between the polarization P, magnetization M, and spiral wave vector Q in CoCr2O4, which has a ferrimagnetic conical-spiral magnetic order. For example, P suddenly jumps and changes its sign at the magnetic lock-in transition (T-L) with thermal variation, or with isothermal variation of H (without changing its direction) at T-L, which surprisingly occurs without change in spiral handedness (i.e., the sign of Q). The presence of multiple spiral sublattices may be behind this unusual behavior.
Thermally or Magnetically Induced Polarization Reversal in the Multiferroic CoCr(2)O(4)
(2009-02-13)
Choi, Y. J.
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Okamoto, J.
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Huang, D. J.
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Chao, K. S.
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Lin, H. J.
We report the unexpected evolution, with thermal and magnetic-field (H) variations, of the interrelation between the polarization P, magnetization M, and spiral wave vector Q in CoCr(2)O(4), which has a ferrimagnetic conical-spiral magnetic order. For example, P suddenly jumps and changes its sign at the magnetic lock-in transition (T(L)) with thermal variation, or with isothermal variation of H (without changing its direction) at T(L), which surprisingly occurs without change in spiral handedness (i.e., the sign of Q). The presence of multiple spiral sublattices may be behind this unusual behavior.
Quantitative Assessment of Hepatic Fat of Intact Liver Tissues with Coherent Anti-Stokes Raman Scattering Microscopy
(2009-02-15)
Wu, Yao-Ming
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Chen, Hung-Che
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Chang, Wei-Tien
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Jhan, Jhen-Wei
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Lin, Hung-Lung
A fatty liver might progress from being a benign fatty liver, to steatohepatitis, cirrhosis, or even hepatocellular carcinoma. The great prevalence and severe outcome have warranted much investigation of the pathology and the development of effective therapies, which involve animal studies requiring critical evaluation of the hepatic fatty change. Histological examination and wet chemical analysis of liver biopsy specimens are generally employed for this purpose despite numerous procedures being involved. Using coherent anti-Stokes Raman scattering (CARS) microscopy, we have demonstrated the specific imaging of fat droplets in intact liver tissues and extracted the hepatic fat content through image analysis while eliminating laborious procedures required by traditional histopathological. examination. The content of hepatic fat measured with CARS imaging was correlated strongly with that determined by biochemical analysis (R(2) = 0.89) over a pathologically significant range of the hepatic fat (from 2% to 20% of the total mass of tissue). Our work validates the quantitative assessment of fat in intact tissue through the use of CARS microscopy. When combined with the increasingly diverse animal models of diseases related to metabolic disorders of lipids, our approach is extensible to enable acquiring important insight into the genetic, environmental, and dietary factors affecting the uptake and accumulation of fat within tissues.
Numerical study on micro-reformer performance and local transport phenomena of the plate methanol steam micro-reformer
(2009-02-15)
Hsueh, Ching-Yi
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Chu, Hsin-Sen
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Yan, Wei-Mon
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機械工程學系
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Department of Mechanical Engineering
The objective of this work is to investigate the transport phenomena and performance of a plate steam methanol micro-reformer. Micro channels of various height and width ratios are numerically analyzed to understand their effects on the reactant gas transport characteristics and micro-reformer performance. In addition, influences of Reynolds number and geometric size of micro channel on methanol conversion of micro-reformer and gas transport phenomena are also explored. The predicted results demonstrated that better performance is noted for a micro channel reformer with lower aspect-ratio micro channel. This is due to the larger the chemical reaction surface area for a lower aspect-ratio channel reformer. It is also found that the methanol conversion decreases with increasing Reynolds number Re. The results also indicate that the smaller micro channel size experiences a better methanol conversion. This is due to the fact that a smaller micro channel has a much more uniform temperature distribution, which in turn, fuel utilization efficiency is improved for a smaller micro channel reformer. (C) 2008 Elsevier B.V. All rights reserved.
Ultrafast optical probes of polaron dynamics in La0.7Ca0.3MnO3 thin films
(2009-02-15)
Wu, K. H.
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Hsu, T. Y.
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Shih, H. C.
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Chen, Y. J.
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Luo, C. W.
In this work, we use ultrafast optical pump-optical probe spectroscopy to probe the polaron dynamics in La0.7Ca0.3MnO3 (LCMO) thin films. The temporal evolution in transient reflectivity change Delta R/R exhibits two relaxing components: a fast component with a time constant of subpicosecond and a slow component with time constant ranging from tens of picoseconds to hundreds of picoseconds. The amplitude of the fast component, though has been seldom discussed before, exhibits the similar temperature dependence with that of the resistivity and the neutron scattering intensity due to nanoscale correlated polarons. The results strongly suggest that the fast photoinduced reflectivity change may have been due to the photoexcitation and trapping process of correlated Jahn-Teller polarons in the paramagnetic and ferromagnetic phases and, thus, implies the presence of electronic inhomogeneity in LCMO manganites.
Using C-band erbium-doped fiber amplifier with two-ring scheme for broadly wavelength-tuning fiber ring laser
(2009-02-15)
Yeh, C. H.
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Shih, F. Y.
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Wen, S.
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Chow, C. W.
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Chi, S.
In this demonstration, we propose and experimentally investigate a broad and stable wavelength-tuning fiber laser employing a C-band erbium-doped fiber amplifier (EDFA) and coupled-ring cavity scheme. Based on the proposed laser scheme, the wavelength-tuning range can be tuned in S- to C-bands (from 1510.0 to 1562.0 nm) due to the properly control of cavity loss. In addition, the performances of side-mode suppression ratio (SMSR), optical signal to noise ratio (OSNR), and output power and wavelength are also discussed and analyzed over the wavelength-tuning range. (C) 2008 Elsevier B.V, All rights reserved.
Organic light-emitting devices based on solution-processible quinolato-complex supramolecules
(2009-02-15)
Cheng, Jung-An
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Chen, Chin H.
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Shieh, Han-Ping D.
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光電工程學系
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顯示科技研究所
This paper discusses a new type of supramolecular material tris{5-N-[3-(9H-carbazol-9-yl)propyl]-N-(4-methylphenyl)aminesulfonyl-8-hydroxyquinolato} aluminum(III), Al(SCarq)(3), which we synthesized using three 5-N-[3-(9H-carbazol-9-yl)propyl]-N-(4-methylphenyl)aminesulfonyl-8-hydroxyquinoline as bidentate ligands. The peak photoluminescence in the solid phase appears at 488 nm. In cyclic voltammetric measurement, two oxidation peaks, which were obtained at -5.6 and -5.9eV, correspond to HOMO sites of carbazoyl and aluminum quinolates, respectively. in the investigation of solid morphological thin film, the flat surface was investigated using an atomic force microscope. The root mean square (rms) and mean roughness (R(a)) were respectively measured to be 0.427 and 0.343 nm. For the fabrication of organic light-emitting devices (OLEDs) using spin-coating techniques, the turn-on voltage and maximum luminescence of the optimized electroluminescence device, glass/ITO (20 nm)/PEDOT: PSS (75 nm)/Al(SCarq)(3) (85 nm)/BCP (8 nm)/LiF (1 nm)/Al (200 nm), were respectively 9.6 V and 35.0 cd m(-2). Due to the electroplex formation between the carbazole (electron-donor) and the aluminum quinolates (electron-acceptor) moieties under an applied DC bias, the chromaticity of electroluminescence shifted to green-yellow with 1931 CIE(x,y) (0.40, 0.47). (C) 2008 Elsevier B.V. All rights reserved.
Functional analysis of the evolutionarily conserved cis-regulatory elements on the sox17 gene in zebrafish
(2009-02-15)
Chan, Tzu-Min
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Chao, Chung-Hao
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Wang, Horng-Dar
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Yu, Yen-Ju
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Yuh, Chiou-Hwa
The Sox17 is an important transcription factor for endodermal cells (Danio rerio). According to the predictions of the GRNs, based on perturbation experiments and literature search, the sox17 gene is engaged with two other regulatory genes, sox32 and pou5f1. Nodal signaling operated on several endoderm-specific transcription factors to determine the endoderm specification. In addition, endoderm specification requires the Fgf and Bmp signaling pathways to be repressed in the cells which will become endoderm. It is predicted that Nodal activates sox32 and works synergistically with Pou5f1 to activate sox17 Bmp represses the expression of sox17 on the ventral side and Fgf represses it on the dorsal side. The regulatory inputs of sox17 at the genomic sequence level are not known. Here, we have uncovered the relevant sox17 cis-regulatory elements, and examined the specific input predictions of the GRNs. We discovered three conserved modules, A, 13, and C, with a synergistic effect among them. We revealed that the Pou5f1-binding element on the B module and the Sox32-binding element on the C module work synergistically. Furthermore, an evolutionarily non-conserved R module exhibits a repressive effect on both the ventral and dorsal side. We have directly demonstrated the structural and functional relationships of the genomic code at this key node of the endoderm GRNs in zebrafish development. This information provides new insight into the complexity of endoderm formation and serves as a valuable resource for the establishment of a complete endoderm gene regulatory network. (c) 2008 Elsevier Inc. All rights reserved.
Long paths in hypercubes with conditional node-faults
(2009-02-15)
Kueng, Tz-Liang
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Liang, Tyne
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Hsu, Lih-Hsing
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Tan, Jimmy J. M.
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資訊工程學系
Let F be a set of f <= 2n - 5 faulty nodes in an n-cube Q(n) such that every node of Q(n) still has at least two fault-free neighbors. Then we show that Q(n) - F contains a path of length at least 2(n) - 2f - 1 (respectively, 2(n) - 2f - 2) between any two nodes of odd (respectively, even) distance. Since the n-cube is bipartite, the path of length 2(n) - 2f - 1 (or 2(n) - 2f - 2) turns out to be the longest if all faulty nodes belong to the same partite set. As a contribution, our study improves upon the previous result presented by [J.-S. Fu, Longest fault-free paths in hypercubes with vertex faults, Information Sciences 176 (2006) 759-771] where only n - 2 faulty nodes are considered. (c) 2008 Elsevier Inc. All rights reserved.