Browsing by Issue Date, starting with "2001-04-24"

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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
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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
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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.
Characteristics of fluorinated amorphous carbon films and implementation of 0.15 mu m Cu/a-C : F damascene interconnection
(2001-05-01)
Shieh, JM
;
Suen, SC
;
Tsai, KC
;
Dai, BT
;
Wu, YC
Fluorinated amorphous carbon films (a-C:F) deposited by plasma enhanced chemical vapor deposition with low dielectric constant (K similar to2.3), thermal stability (higher than 400 degreesC) and acceptable adhesion to a cap layer such as SiOF or SiO2 were obtained by varying the range of content ratios between carbon and fluorine, the rf power, the process pressure and the base temperature. Standard x-ray photoelectron spectroscopy and thermal desorption spectroscopy metrologies were employed to characterize the deposited a-C:F films. The damascene pattern with 0.15 mum and an etching selectivity of more than 50 (a-C:F/SiOF, SiO2) was implemented by a mixture of etching gases of N-2+O-2. The bias power, rf power and gas hows were incorporated to optimize the etching recipe for achieving a damascene profile with a high aspect ratio. The scanning electron microscope results showed that a better etch profile can be obtained at higher bias power. In our damascene architecture, the etching stop layer or hard mask of both SiOF and SiO2 was studied. The SiOF, providing a lower dielectric constant than SiO2, would especially reduce the entire effective dielectric constant. Furthermore, we integrated electroplated copper into trenches or vias as small as 0.15 mum, with aspect ratio of 6. (C) 2001 American Vacuum Society.
High-order MS_CMAC neural network
(2001-05-01)
Jan, JC
;
Hung, SL
;
土木工程學系
;
Department of Civil Engineering
A macro structure cerebellar model articulation controller (CMAC) or MS_CMAC was developed by connecting several one-dimensional (1-D) CMACs as a tree structure, which decomposes a multidimensional problem into a set of 1-D subproblems, to reduce the computational complexity in multidimensional CMAC, Additionally, a trapezium scheme is proposed to assist MS_CMAC to model nonlinear systems. However, this trapezium scheme cannot perform a real smooth interpolation, and its working parameters are obtained through cross-validation. A quadratic splines scheme is developed herein to replace the trapezium scheme in MS_CMAC, named high-order MS_CMAC (HMS_CMAC), The quadratic splines scheme systematically transforms the stepwise weight contents of CMACs in MS_CMAC into smooth weight contents to perform the smooth outputs, Test results affirm that the HMS_CMAC has acceptable generalization in continuous function-mapping problems for nonoverlapping association in training instances. Nonoverlapping association in training instances not only significantly reduces the number of training instances needed, but also requires only one learning cycle in the learning stage.
Anisotropic self-diffraction under Bragg mismatching
(2001-05-01)
Wang, B
;
Sun, CC
;
Yang, TH
;
Ye, P
;
Chang, JY
Anisotropic self-diffraction (ASD) under Bragg mismatch has been studied. We derive a solution that can describe well the diffraction characteristics of the anisotropic self-diffraction under Bragg mismatch. The solution is useful for estimating the Bragg constraint when the ASD is applied to optical information processing. Both the theory and the experiment are presented.
Multiple melting behavior of poly(butylene-2,6-naphthalate)
(2001-05-01)
Ju, MY
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
Multiple melting behaviors of poly(butylene-2,6-naphthalate) (PBN) prepared by various crystallization conditions were studied by differential scanning calorimetry at a heating rate of 10 degreesC/min. It is found that the crystallization rate of PEN is so rapid that the glass transition temperature cannot be detected by simply heating the quenched sample. Two melting peaks are generally perceptible in a heating scan for isothermally crystallized samples that can be properly explained by the model proposed by Zhou and Clough (Polym Engng Sci 28 (1988) 65). The low-temperature melting peak can be ascribed to the melting of primary and secondary crystals generated during the crystallization or annealing process, while the high-temperature melting peak comes from the significant contribution of the melting of recrystallized species formed during heating. The step-crystallization was performed to clarify the relationship between the melting behavior and crystal modifications of PEN. In this study, it is found that the melting behavior of PEN is independent of the crystal forms and dominated by the crystal lamellar thickness and the perfection of crystals, which are dependent upon the thermal history. Finally, an equilibrium melting temperature of 276 degreesC is obtained for the neat PEN, which is lower than that published in the literature. (C) 2001 Elsevier Science Ltd. All rights reserved.
A simple recursive method for converting a chain code into a quadtree with a lookup table
(2001-05-01)
Chen, Z
;
Chen, IP
;
資訊工程學系
;
Department of Computer Science
We present a simple recursive method for converting a chain code into a quadtree. We generate the quadtree black nodes level by level, starting from the finest resolution (i.e. the bottom) level toward the coarsest resolution (i.e. the top) level. Meanwhile, at each resolution level a new object border is revealed after the removal of the black nodes. The chain code elements for this new object border can be easily generated. Thus, the quadtree black nodes and the chain code elements of the new object border are generated side by side and their generations constitute a basic cycle of the conversion process. We show the generations can be done with the aid of a lookup table. Finally, we compare our method with the existing two-phase methods exemplified by Samet's method in terms of the total numbers of major operations including node allocations, node color filling, and node pointer linking. It indicates that our method is conceptually simpler and runs faster. (C) 2001 Elsevier Science B.V. All rights reserved.
Investigations of effects of bias polarization and chemical parameters on morphology and filling capability of 130 nm damascene electroplated copper
(2001-05-01)
Chang, SC
;
Shieh, JM
;
Lin, KC
;
Dai, BT
;
Wang, TC
Through elucidating the effects of current density, cupric ion concentration, bath temperature, and air agitation on plating uniformity and filling capability of copper electroplating, the deposition of copper in an acid copper electrolyte will be illustrated to scale down to the sub-0.13 mum features with uniform plating, which is required by chemical mechanical polishing in current damascene techniques. In order to achieve the defect-free filling in sub-0.13 mum vias and trenches, the electrolyte must be composed of proper amounts of cupric ions, sulfuric acid, chloride ions, wetting agent, and filling promoter. The supplied current controlled at a lower current density, agitation acceded to the electroplating process were found as further keys. In the electrolyte, the filling promoter was consisted essentially of thiazole derivatives with benzyl groups and amino-group (-NH2) offering sufficient inhibition on copper depositing and selective inhibition gradient. Moreover, a lower resistivity film and higher filling capability could be obtained by using periodic pulse current plating as compared with direct current plating. (C) 2001 American Vacuum Society.
Annealing temperature dependence of electric conduction and capacitance dispersion in nitrogen-implanted GaAs
(2001-05-01)
Chen, JF
;
Huang, MM
;
Wang, JS
;
電子物理學系
;
Department of Electrophysics
The annealing behavior of nitrogen-implanted GaAs samples has been investigated by secondary ion mass spectroscopy, current-voltage (I-V) and capacitance-frequency (C-F) measurements. The I-V data show that the conductivity of as-implanted samples is dominated by variable-range hopping beta een defect states below 300 K. The implanted layer becomes highly resistive after annealing. The activation energy of the resistance is found to increase from 0.2 eV for as-implanted samples to 0.71 eV for 950 degreesC-annealed samples. Significant capacitance dispersion is observed over frequency for implanted samples. Based on a proposed equivalent circuit, the high-frequency capacitance dispersion is shown to be the result. of resistance-capacitance (RC) time constant effects. The increase of activation energy of the resistance can be explained by the creation of deep traps by high temperature annealing. Traps at 0.69 eV and 0.82 eV are detected for 700 degreesC and 950 degreesC-annealing, respectively.
Effect of catalyst on growth behavior of carbon nanotube synthesizing by microwave heating thermal chemical vapor deposition process
(2001-05-01)
Chen, SC
;
Shih, LY
;
Chang, YC
;
Tu, GC
;
Lin, IN
A modified chemical vapor deposition process, which utilizes a susceptor to absorb the microwave and to self generate the heat, for heating up the Si substrate, was used for growing carbon nanotubes (CNTs). The advantage of such a process is that the deposition chamber can be maintained at around room temperature with only the substrates localized heated, such that the deposition temperature can be more precisely controlled. The influence of the pretreatment process for catalyst-coated Si substrates on growth behavior of CNTs and the related electron field emission properties were systematically examined. Among the form of catalyst used, the Fe(NO3)(3)-ethythersilicate mixture performs much better than the de sputtered Fe films. The higher the concentration of Fe species in the catalyst mixture, the denser the CNTs formed on the subs;rates, resulting in better held emission properties. Thus grown CNTs can be turned on at a very low field (E(0)congruent to0.78 V/mum), achieving a very large emission current density (J(e)congruent to 13 mA/cm(2)) at 5.5 V/mum applied field. (C) 2001 American Vacuum Society.