Browsing by Issue Date, starting with "2001-04-07"

Now showing 1 - 20 of 76584

Nanoscale surface electrical properties of indium-tin-oxide films for organic light emitting diodes investigated by conducting atomic force microscopy
(2001-04-07)
Lin, HN
;
Chen, SH
;
Perng, GY
;
Chen, SA
;
電子物理學系
Nanoscale surface electrical properties of indium-tin-oxide films prepared by different cleaning methods for use as anode materials in organic light emitting diodes are studied by conducting atomic force microscopy. It is found that most of the surface area possesses a nonconducting feature, and an ultraviolet-ozone treatment produces the most nonconductive sample. The conducting regions, which distribute randomly and range from 6 to 50 nm in size, are attributed to the existence of Sn-rich oxide by a comparison with reported scanning electron microscopy images. After scanning the tip with a bias of -8 V on the nonconducting regions, oxide decomposition occurs on as-received and wet-cleaning processed samples, whereas no structure change appears on the ozone treated sample. The results indicate that the generation of stable oxide after ozone treatment is one of the origins for improved device performance. (C) 2001 American Institute of Physics.
Down-regulation of matrix Gla protein messenger RNA in human colorectal adenocarcinomas
(2001-04-10)
Fan, CW
;
Sheu, DL
;
Fan, HA
;
Hsu, KC
;
Chang, CA
Matrix Gla protein (MGP) is a vitamin K-dependent extracellular matrix protein commonly found in a variety of tissues. In this study, we describe the potential use of MGP gene expression as the tumor marker of colorectal cancer. A decrease in expression of the MGP gene was also discovered in colorectal cancer using differential screening of cDNA libraries. The MGP expression in 80 human colorectal adenocarcinomas was quantified by a Northern blot analysis to better define the expression pattern of MGP in colorectal cancer. The expression of MGP mRNA was reduced in 63 of 80 (79%) colorectal adenocarcinomas (P < 0.001) as compared to the mRNA in adjacent normal tissue, implying that a decrease in MGP expression is associated with colorectal cancer development. The proportion of tumors with downregulated expression of MGP was lower in Duke's A/B than Duke's C/D (34 of 47 versus 26 of 33, respectively) tumors and was lower in moderate differentiation than poor differentiation (44 of 64 versus 16 of 16, respectively). However, chi (2) analysis does not reveal any correlation between a loss of MGP expression and tumor progression or differentiation state. In conclusion, the downregulation of MGP mRNA generally occurs in colorectal adenocarcinomas. Although the role of MGP in cancer development is unknown, the reduced expression of MGP may be used to distinguish the normal colorectal cells from malignant cells. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.
Spin-orbit splitting in semiconductor quantum dots with a parabolic confinement potential
(2001-04-15)
Voskoboynikov, O
;
Lee, CP
;
Tretyak, I
;
交大名義發表
;
National Chiao Tung University
We present a theoretical study of the effect of spin-orbit interaction on the electron energy spectrum of cylindrical semiconductor quantum dots. The study is based on a simple effective one-band approximation. The dependence of energy levels on parameters of the dots and the applied external magnetic field is studied. Contributions of the bulk inversion asymmetry (the Dresselhaus term) and the system inversion asymmetry (the Rashba term) to the spin splitting of the electron energy states are discussed. The spin splitting of electron states with nonzero angular momentum is demonstrated theoretically for InSb and InAs small quantum dots at zero magnetic field. We find a "crossing" of the electron energy stales with the same angular momentum and different spin polarizations in a nonzero magnetic field.
Characteristics of YBa2Cu3O7 thin films deposited on substrates buffered by various TiO2 layers
(2001-04-15)
Lin, PL
;
Liu, CW
;
Hsieh, CC
;
Wu, KH
;
Juang, JY
Titanium nitride (TiN) and superconducting YBa2Cu3O7 (YBCO) thin films have been deposited sequentially on SrTiO3(STO)(100) substrates by in situ pulsed laser ablation. The TiN films were originally intended to serve as the lower contact electrode of the c-axis YBCO thin films. It was found that, although high-quality YBCO films could be obtained with the YBCO/TiN/STO(100) bilayer structure, the TiN(100) layer was oxidized which changed the structure into YBCO/TiO2/STO(100) during YBCO deposition. Comparative studies of depositing YBCO films directly onto a dc-sputtered TiO2/STO(100) template conventionally used in the selective epitaxial growth (SEG) process have, however, resulted in formation of a nonsuperconducting YBCO top layer. The characteristics of the resultant TiO2 layers obtained using various processes were analyzed to delineate the apparent discrepancies.
Rapid process for purification of an extracellular beta-xylosidase by aqueous two-phase extraction
(2001-04-15)
Pan, IH
;
Li, YK
;
應用化學系
;
Department of Applied Chemistry
A rapid process for purification of an extracellular beta -xylosidase with high purity was developed. The manipulation involved the precipitation of protein from culture medium and the extraction of enzyme from the resuspended elude protein solution by an aqueous-two phase separation. A linear random copolymer, PE62, with 20% ethylene oxide and 80% propylene oxide was employed in both stages of the purification. The enzyme was precipitated effectively by using 10% (w/v) PE62 and 5% (w/v) Na2HPO4. The aqueous two-phase extraction was performed with PE62 (10%)-NaH2PO4 (15%) as phase-forming reagent. SDS-PAGE analysis revealed that the purified enzyme is near homogeneity. The yield is about 100% with a purification factor of 8.8-fold. The whole process can be completed within an hour without any column chromatography. (C) 2001 Elsevier Science B.V. All rights reserved.
H-infinity control for nonlinear affine systems: a chain-scattering matrix description approach
(2001-04-15)
Hong, JL
;
Teng, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper combines an alternative chain-scattering matrix description with (J, J')-lossless and a class of conjugate (- J, - J')-lossless systems to design a family of nonlinear H-infinity output feedback controllers. The present systems introduce a new chain-scattering setting, which not only offers a clearer expression for the solving process of the nonlinear H-infinity control problem but also removes the fictitious signals introduced by the traditional chain-scattering approach. The intricate nonlinear affine control problem thus can be transformed into a simple lossless network and is easy to deal with in a network-theory context. The relationship among these (J, J') systems, L-2-gain, and Hamilton-Jacobi equations is also given. Block diagrams are used to illustrate the central theme. Copyright (C) 2001 John Wiley & Sons, Ltd.
Precision calculation of magnetization and specific heat of vortex liquids and solids in type-II superconductors
(2001-04-16)
Li, DP
;
Rosenstein, B
;
交大名義發表
;
電子物理學系
;
National Chiao Tung University
A new systematic calculation of magnetization and specific heat contributions of vortex liquids and solids is presented. We develop an optimized perturbation theory for the Ginzburg-Landau description of thermal fluctuations effects in the vertex liquids. The expansion is convergent in contrast to the conventional high temperature expansion which is asymptotic. In the solid phase we calculate the first two orders which are already quite accurate. The results are in good agreement with existing Monte Carlo simulations and experiments. Limitations of various nonperturbative and phenomenological approaches are noted. In particular, we show that thew is no exact intersection point of the magnetization curves.
General fuzzy piecewise regression analysis with automatic change-point detection
(2001-04-16)
Yu, JR
;
Tzeng, GH
;
Li, HL
;
管理學院
;
運輸與物流管理系註：原交通所+運管所
Yu et al. (Fuzzy Sets and Systems 105 (1999) 429) performed general piecewise necessity regression analysis based on linear programming (LP) to obtain the necessity area. Their method is the same as that according to data distribution, even if the data are irregular, practitioners must specify the number and the positions of change-points. However, as the sample size increases, the number of change-points increases and the piecewise linear interval model also becomes complex. Therefore, this work devises general fuzzy piecewise regression analysis with automatic change-point detection to simultaneously obtain the fuzzy regression model and the positions of change-points. Fuzzy piecewise possibility and necessity regression models are employed when the function behaves differently in different parts of the range of crisp input variables. As stated, the above problem can be formulated as a mixed-integer programming problem. The proposed fuzzy piecewise regression method has three advantages: (a) Previously specifying the number of change-points, then the positions of change-points and the fuzzy piecewise regression model are obtained simultaneously. (b) It is more robust than conventional fuzzy regression. The conventional regression is sensitive to outliers. In contrast, utilizing piecewise concept, the proposed method can deal with outliers by automatically segmenting the data. (c) By employing the mixed integer programming, the solution is the global optimal rather than local optimal solution. For illustrating more detail, two numerical examples are shown in this paper. By using the proposed method, the fuzzy piecewise regression model with detecting change-points can be derived simultaneously. (C) 2001 Elsevier Science B.V. All rights reserved.
Chain conformation and crystallization behavior of the syndiotactic polystyrene nanocomposites studied using Fourier transform infrared analysis
(2001-04-24)
Wu, HD
;
Tseng, CR
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
Analyses of the effects of montmorillonite (clay) on the chain conformation and crystallization of syndiotactic polystyrene (s-PS) thin films are investigated using FTIR spectroscopy, X-ray diffraction, and TEM. The clay is dispersed into the s-PS matrix using a solution blending with scale in 1-2 nm or in a few tenths to 100 nm, depending on whether a surfactant is added or not. Upon adding clay, the chain conformation of s-PS tends to convert to TTTT from rTTGG after drying because the highly dispersed clay overcomes the energy barrier of chain conformation transformation. This phenomenon leads to a change in a conventional mechanism of molecular packing for s-PS in the drying stage. During melt-crystallization, clay plays a vital role in facilitating the formation of the thermodynamically favored all-trans p form crystal, particularly on the s-PS thin film. When the s-PS is melt-crystallized at a cooling rate of 1 degreesC/min from 320 degreesC, the highest absolute crystallinity of beta form up to 0.56 occurs in the clay dispersibility of few tenths to 100 nm in the s-PS matrix; then dispersibility is of 1-2 nm (0.49), and the final one is of pure s-PS (0.42). Evidently, clay significantly affects the chain conformation and crystallization of s-PS.
Non-linear dynamics and chaos control of a physical pendulum with vibrating and rotating support
(2001-04-26)
Ge, ZM
;
Yang, CH
;
Chen, HH
;
Lee, SC
;
機械工程學系
The dynamic behavior of a physical pendulum system of which the support is subjected to both rotation and vertical vibration are studied in this paper. Both analytical and computational results are employed to obtain the characteristics of the system. By using Lyapunov's direct method the conditions of stability of the relative equilibrium position can be determined. Melnikov's method is applied to identify the existence of chaotic motion. The incremental harmonic balance method is used to find the stable and unstable periodic solutions For the strong non-linear system. By applying various numerical results such as phase portrait, Pioncare map. time history and power spectrum analysis, a variety of the periodic solutions and the phenomena of the chaotic motion can be presented. The effects of the changes of parameters in the system could be found in the bifurcation and parametric diagrams. Further, chaotic motion can be verified by using Lyapunov exponent and Lyapunov dimension. The global analysis of basin boundary and fractal structure are observed by the modified interpolated cell mapping method. Besides, non-feedback control, delayed feedback control, adaptive control, and variable structure control are used to control the chaos effectively. (C) 2001 Academic Press.
秦俑看病
(2001-04-29)
管管
Application of 2-D random generators to the study of solute transport in fractures
(2001-05-01)
Su, HC
;
Kinzelbach, W
;
土木工程學系
;
Department of Civil Engineering
Two fields with random aperture distribution and different spatial structures are taken as models to study solute transport in fractures. One network has non-vaunishing long range correlations and represents a fractal pattern. The other one has a finite correlation length and an exponential covariance function. Based on these fields, two physical fracture models were produced and used to record the movement of a coloured solute by means of a CCD camera. The pictures obtained were analyzed with image processing methods. A front tracking algorithm shows that the growth law of the frontal variance is a power law of time with the exponent depending on the Hut-st coefficient of the aperture distribution in the case of the fractal pattern, while it is a linear function of time for the case of the finite correlation length.
Performance enhancement of IP forwarding by reducing routing table construction time
(2001-05-01)
Wang, PC
;
Chan, CT
;
Chen, YC
;
資訊工程學系
;
Department of Computer Science
In previous work, Lampson et al, proposed an IP lookup algorithm which performs binary search on prefixes (BSP) [3], The algorithm is attractive for IPv6 because of its bounded worst-case memory requirement. Although for the sake of fast forwarding, the cost paid for the slowing down insertion is reasonable, the performance of routing-table reconstruction in BGP is too time-consuming to handle the frequent route updates. In this letter, we propose a fast forwarding-table construction algorithm which can handle more than 3600 route updates per second, Moreover, it is simple enough to fulfill the need of fast packet forwarding.
High-bandwidth x86 instruction fetching based on instruction pointer table
(2001-05-01)
Chiu, JC
;
Chung, CP
;
資訊工程學系
;
Department of Computer Science
Providing higher degree superscalar instruction fetching is a major concern in a high performance superscalar processor design. In x86 architectures, the variable-length instructions make fetching multiple instructions in a cycle difficult. A common practice is to use predecoded information to help in instruction fetching, while the complex instruction formats induce high redundancies in storing and processing the pre-decoded information in the cache. In the paper, the authors propose to use an Instruction Identifier to predict instruction length and store the instruction pointers as superscalar instruction group indicators. With this method, the difficulty of achieving a high instruction fetch degree (>3) can be overcome. Simulation results suggest that the Instruction Identifier with a 64-entry table is a good performance/cost choice. In the meantime, as the table size decreases, the prediction scheme becomes increasingly important. Moreover, simulation and circuit synthesis show that this design is feasible for high clock rate design.
A possibilistic decision logic with applications
(2001-05-01)
Liau, CJ
;
Liu, DR
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
In this paper, we investigate a knowledge representation formalism in the context of fuzzy data tables. A possibilistic decision logic incorporating linguistic terms is proposed for representing and reasoning about knowledge in fuzzy data tables. Two applications based on the logic are described. The first is the extraction of fuzzy rules from general fuzzy data tables. In this application, the knowledge in the tables may be made explicit by the formulas of the logic or used implicitly in decision-making. The second is for the fuzzy quantization problem of precise data tables. It can be viewed as a special case of the first, however, due to some special properties of the problem, a polynomial time rule extraction process can be obtained. Finally, the relationship of the logic with some works for handling uncertain information in data tables is also discussed.
Real-time deadlock-free control strategy for single multi-load automated guided vehicle on a job shop manufacturing system
(2001-05-01)
Liu, FH
;
Hung, PC
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
An unmanned automated job shop manufacturing system with a single multi-load automated guided vehicle, which traverses around a single-loop guidepath, is considered in this work. This type of shop design is often used as an independent sector of some complex AGV layouts, such as tandem, segmented bi-directional single-loop and divided configurations. The type of multi-load vehicle is a good alternative against using more single-load vehicles to serve a higher transportation demand. To an unmanned automated manufacturing system, the management of finite system resources, e.g. finite input/output queuing space and transporting carriers, plays a vital role in avoiding system deadlocks and machine blockages. The proposed control strategy for a single multi-load vehicle uses global shop real-time information to achieve the objectives: avoid shop deadlocks caused by inappropriate job movement as well as satisfy the system transport requirement. The efficiency of the proposed vehicle control strategy and the other two expanded strategies under various parameter designs are verified by computer simulation.
The inequality between the coefficient of determination and the sum of squared simple correlation coefficients
(2001-05-01)
Shieh, GW
;
管理科學系
;
Department of Management Science
The inequality between the coefficient of determination and the sum of two squared simple correlation coefficients in a two-variable regression model is reexamined through two relative measures. They are the relative coefficient of determination and the relative simple correlation, which are the ratio of the coefficient of determination to the sum of squares of the two simple correlations and the ratio of two simple correlations, respectively. This approach not only permits new insights into their relationship hut also allows clear and informative visual representations of various aspects of the counterintuitive condition. We consider the occurrence and corresponding magnitude? probability and expected magnitude of the enhancement-synergism situation. Numerical examples are presented to illustrate these phenomena.
Decay rate of a Wannier exciton in low-dimensional systems
(2001-05-01)
Chen, YN
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
The superradiant decay rate of a Wannier exciton in a one-dimensional system is studied. The crossover behavior from 1D chain to 2D film is also examined. It is found that the decay rate shows a oscillatory dependence on the channel width L. When the quasi-1D channel is embeded with planar microcavities, it is show that the dark mode exciton can be examined experimentally.
Data broadcasting and seamless channel transition for highly demanded videos
(2001-05-01)
Tseng, YC
;
Yang, MH
;
Hsieh, CM
;
Liao, WH
;
Sheu, JP
One way to broadcast a popular video is to use a number of dedicated channels, each responsible for broadcasting some portion of the video periodically in a predefined way. The stress on channels can be alleviated, and new viewers do not have to wait long to start their playback, Many approaches falling in this category have been proposed, One such scheme that interests us is the fast broadcasting (FB) scheme, which can broadcast a video using k channels by incurring at most O(D/2(k)) waiting time on new-coming viewers, where D is the length of the video. In this paper, we consider a set of videos, each being broadcast by the FB scheme, Since the levels of demands on these videos may change by time, it is sometimes inevitable to change the numbers of channels assigned to some videos. We propose a novel seamless channel transition enhancement on top of the FB scheme to dynamically change the number of channels assigned to a video on-the-fly. Clients currently viewing this video will not experience any disruption because of the transition. A channel allocation scheme is also proposed based on the arrival rates of videos to minimize the average waiting experienced by all viewers, From the system manager's point of view, the enhancement will make the FB scheme more attractive.
Electrical properties of the free-standing diamond film at high voltages
(2001-05-01)
Huang, BR
;
Ke, WC
;
Chen, WK
;
電子物理學系
;
Department of Electrophysics
Polycrystalline diamond films were deposited on P-type (100) silicon substrates by the microwave plasma chemical vapor deposition system. The free-standing diamond film was then obtained by etching the silicon substrate with a KOH I solution. It was found that more non-diamond components, i.e., SiC and amorphous carbon, existed on the bottom surface of the free-standing diamond film. Two different contact geometries, coplanar contact and sandwich contact geometries, were used to characterize the in-plane and transverse hi.-h-voltage electrical properties of the free-standing diamond film, respectively. The transverse electrical property of the free-standing diamond film showed the asymmetric current-voltage (1-V) characteristic and lower break-down voltage at -220 V and 850 V. However, the in-plane electrical property exhibited the symmetric I-V characteristic in the range of - 1100 V to 1100 V. The electrical properties were successfully represented by the Frenkel-Poole conduction mechanism at high voltages (> 200 V). The simulated results indicated that the breakdown field was strongly related to the Coulombic center density of the free-standing diamond film.