Browsing by Issue Date, starting with "1998-06-08"

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Properties of thin Ta-N films reactively sputtered on Cu/SiO2/Si substrates
(1998-06-08)
Chuang, JC
;
Chen, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work studied the thin film properties of 200 Angstrom Ta and Ta-N films reactively sputtered on the Cu/SiO2/Si substrates. The nitrogen atomic concentration in the Ta-N film was found to saturate at about 30%. Excessive sputtering gas flow, especially the N-2 gas, caused surface damage to the sputter deposited films. Thermal annealing in N-2 ambient at temperatures up to 700 degrees C did not change the atomic concentrations and the chemical states of Ta and N in the Ta and Ta-N films. The thermal annealing resulted in the grain growth and the healing of sputter damage, but it also induced new defects in the Ta-N films due to thermal stress. This presents a reliability problem in process application involving high temperature thermal cycle. (C) 1998 Elsevier Science S.A. All rights reserved.
管管娶嬌娘,喜宴忒詩意
(1998-06-10)
江中明
Adaptive filter bank reconstruction using fast multichannel RLS algorithms
(1998-06-11)
Chang, DC
;
Wu, WR
;
電信工程研究所
;
Institute of Communications Engineering
The recursive least-squares (RLS) algorithm has been used in the adaptive synthesis filter bank for fast convergence. However, because of interpolation operations involved in the synthesis process, fast RLS algorithms cannot be applied. In this Letter, an approach is proposed that can formulate subband reconstruction as a multichannel filtering problem. This formulation allows the application of fast multichannel RLS algorithms and substantial reduction in computational complexity.
飲者之歌辛鬱-我友管管大喜日詩呈紀弦老師
(1998-06-11)
辛鬱
鐵的說帖
(1998-06-15)
管管
鐵的說帖
(1998-06-15)
管管
鐵的說帖
(1998-06-15)
管管
鐵的說帖
(1998-06-15)
管管
Interference patterns of scattering light induced by orientational fluctuations in an electric-field-biased nematic liquid-crystal film
(1998-06-15)
Shen, YR
;
Chen, SH
;
Hsu, CH
;
Lai, YC
;
光電工程學系
A new light-scattering phenomenon from a planar aligned nematic liquid-crystal film is observed and studied. This new phenomenon exhibits ring patterns in the orthogonal polarization. A simple model based on optical interference has been developed, and its predictions agree well with experimental observation. (C) 1998 Optical Society of America.
Transportation investment project selection using fuzzy multiobjective programming
(1998-06-16)
Teng, JY
;
Tzeng, GH
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
This paper proposes the fuzzy multiobjective programming for the problem of transportation investment project selection (TIPS). The programming then uses the fuzzy spatial algorithm, which calculates the performance of objective achievement and the requirement of resource utilization as of fuzziness, Under a complex and uncertain decision-making environment, there exists a certain degree of interdependence among these transportation investment projects. This paper uses expert evaluation, and conducts, respectively, with the consensus of most of the experts, the decision on interdependence type (complementary and substitutive) and on the degree of fuzzy interdependence. In every iteration of the fuzzy spatial algorithm, the method of ranking fuzzy numbers must be used so as to obtain the ranking for selecting investment projects. This paper has modified the method provided by Kim and Park in order that the preference of most of the decision makers or experts can be overlooked, since the degree of optimism or pessimism can be demonstrated in the profitability of every investment project. In the end, this paper will employ a numerical example to illustrate the method forwarded. (C) 1998 Elsevier Science B.V. All rights reserved.
An approximate approach of global optimization for polynomial programming problems
(1998-06-16)
Li, HL
;
Chang, CT
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Many methods for solving polynomial programming problems can only find locally optimal solutions. This paper proposes a method for finding the approximately globally optimal solutions of polynomial programs. Representing a bounded continuous variable x(i) as the addition of a discrete variable d(i) and a small variable epsilon(i), a polynomial term x(i)x(j) can be expanded as the sum of d(i)x(j), d(j) epsilon(i) and epsilon(i) epsilon(j). A procedure is then developed to fully linearize d(i)x(j) and d(j) epsilon(i), and to approximately linearize epsilon(i) epsilon(j) with an error below a pre-specified tolerance. This linearization procedure can also be extended to higher order polynomial programs. Several polynomial programming examples in the literature are tested to demonstrate that the proposed method can systematically solve these examples to find the global optimum within a pre-specified error. (C) 1998 Elsevier Science B.V.
瘦了的秋月
(1998-06-22)
管管
Two-dimensional beam-scanning phase-shifterless technique using linear active leaky-wave antenna array
(1998-06-25)
Hu, CC
;
Jou, CF
;
Wu, JJ
;
傳播研究所
;
Institute of Communication Studies
A novel two-dimensional electronic beam scanning technique using a linear leaky-wave antenna array with coupled oscillators is introduced, eliminating the need for phase shifters. The measured H-plane main beam carl be continuously scanned from 70 to 40 degrees as the frequency varies from 7.9 to 9.05 GHz. By detuning the free running frequencies of the end elements, the measured E-plane main beam can be continuously scanned from -22 to +26 degrees.
The use of a biomolecular target for crystalline carbon nitride film deposition by Ar ion-beam sputtering without any other source of nitrogen
(1998-06-29)
Chen, LC
;
Lu, TR
;
Kuo, CT
;
Bhusari, DM
;
Wu, JJ
Carbon nitride films have been synthesized by argon ion-beam sputtering from a biomolecular compound target, 8-aza-6-aminopurine (C4N6H4) The compound has a six-membered ring structure similar to that existing in the hypothetical beta-C3N4. Except fur the target material, no other source of nitrogen was used during sputtering deposition. It was found that crystalline carbon nitride with high N/C atomic composition ratios of 0.43-0.56 can be formed even at room temperature. The infrared spectra of the film exhibit two peaks at 1383 and 1643 cm(-1), corresponding to C-N and C=N stretching modes, respectively. No detectable peak at 2200 cm(-1) (C=N stretching mode) is observed. Both x-ray diffraction and transmission electron microscopy show a very strong broad peak at 3.2 Angstrom, comparable to the d spacing of the (110) orientation in the beta-C3N4 structure. However, it is suggested that the film contains a nanocrystalline phase with a crystal structure yet to be determined. (C) 1998 American Institute of Physics.
Nonlocal extended conformal algebras associated with multiconstraint KP hierarchy and their free field realizations
(1998-06-30)
Shaw, JC
;
Tu, MH
;
應用數學系
;
物理研究所
;
Department of Applied Mathematics
We study the conformal properties of the multiconstraint KP hierarchy and its nonstandard partner by covariantizing their corresponding Lax operators. The associated second Hamiltonian structures turn out to be nonlocal extensions of W-n algebra by some integer or half-integer spin fields depending on the order of the Lax operators. In particular, we show that the complicated second Hamiltonian structure of the nonstandard multiconstraint KP hierarchy can be simplified by factorizing its Lax operator to multiplication form. We then diagonalize this simplified Poisson matrix and obtain the free held realizations of its associated nonlocal algebras.
An inheritance flow model for class hierarchy analysis
(1998-06-30)
Chen, JL
;
Wang, FJ
;
資訊工程學系
;
Department of Computer Science
This paper presents an inheritance flow model, which represents the inheritance relationships among classes as a flow graph. A flow operation is associated with each attribute and method in a class to denote the defined (redefined) or inherited member. An inherited member can be deemed as being handled by a sequence of how operations along a path in the flow graph. This model provides several analyses in a class hierarchy, such as implicit inherited member and polymorphic method invocation. These analyses may be applied in various fields of software engineering, such as static analysis, maintenance, and complexity measurement. (C) 1998 Elsevier Science B.V. All rights reserved.
A homophonic DES
(1998-06-30)
Hsieh, TM
;
Yeh, YS
;
Hsieh, YC
;
Wang, CC
;
資訊科學與工程研究所
In this paper, we propose a variant of DES called a homophonic DES. The DES algorithm is strengthened by adding some random bits into the plaintext, which are placed in particular positions to maximize diffusion, and to resist differential attack. (C) 1998 Elsevier Science B.V. All rights reserved.
Barrier properties of very thin Ta and TaN layers against copper diffusion
(1998-07-01)
Wang, MT
;
Lin, YC
;
Chen, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Diffusion barrier properties of very thin sputtered Ta and reactively sputtered TaN films used as a barrier layer between Cu and Si substrates were investigated using electrical measurement and materials analysis. The Cu/Ta/p(+)-n junction diodes with the Ta barrier of 5, 10, and 25 nm thicknesses were able to sustain a 30 min thermal annealing at temperatures up to 450, 500, and 550 degrees C, respectively, without causing degradation to the device's electrical characteristics. The barrier capability of Ta layer can be effectively improved by incorporation of nitrogen in the Ta film using reactive sputtering technique. For the Cu/TaN/p(+)-n junction diodes with the TaN barrier of 5,10, and 25 nm thicknesses, thermal stability was able to reach 500, 600, and 700 degrees C, respectively. We found that failure of the very thin Ta and TaN barriers was not related to Ta silicidation at the barrier/Si interface. Failure of the barrier layer is presumably due to Cu diffusion through the barrier layer during the process of thermal annealing via local defects, such as grain boundaries and stress-induced weak points.
Numerical analysis of a burning droplet with internal circulation in a gravitational environment
(1998-07-01)
Huang, LW
;
Chen, CH
;
機械工程學系
;
Department of Mechanical Engineering
A theoretical analysis of steady burning droplets with internal circulation in the presence of normal atmosphere and gravity is presented. The normalized system governing the gas phase consists of the complete set of conservation equations in r-z coordinates and includes finite-rate global kinetics. For the liquid phase, it includes continuity and momentum conservation equations. Thermodynamic equilibrium is assumed along the gas-liquid interface, which is not stationary. A body-fitted grid generation technique is used to handle irregular boundaries. The parametric study is performed by changing droplet diameter. The induced convection flowfield is presented to demonstrate its interaction with the flame and the liquid flow motion. The predicted results show that there exists one, two, or three cells within the burning droplet, depending on its diameter. The occurrence of an extra cell is due to reverse flow in the gas phase generated by interaction of the induced flow and blowing velocity. Comparison with the case where internal flow is not considered, for a small droplet the effect of internal circulation on mass evaporation rate can be neglected. On the other hand the internal flow will increase the mass evaporation rate.
Fuzzy neural systems for controlling sound localisation in stereophonic reproduction
(1998-07-01)
Chang, PR
;
Tan, TH
;
電信工程研究所
;
Institute of Communications Engineering
The paper presents a new fuzzy logic control (FLC) approach which leads to a stereophonic reproduction controller for localising an auditory image in the desired direction and at the expected distance. Since an auditory event is usually less precisely resolved than the physical sound space, the auditory event need not coincide with a physical sound source, and can occur at a position where nothing is visible to a listener. It turns out that controlling the auditory image is more difficult than the localisation of a sound image. Unlike the conventional sound image localisation approach, our fuzzy logic controller can take account of knowledge in human auditory perception. The ambiguous human auditory perception in conjunction with the spatial reverberation from the surrounding environment can be represented by a number of fuzzy-set values. From these fuzzy representations, the auditory image localisation controller characterises the function of how control outputs depend on control inputs as fuzzy implications or associations. Furthermore, the overall stereophonic reproduction controller can be realised by a 45-rule fuzzy associative memory (FAM) system. The performance of FLC-based auditory image localisation is verified in a number of experiments.