Browsing by Issue Date, starting with "1997-07-31"

Now showing 1 - 20 of 83591

Growth rate control of fumarase (fumA) gene expression in Escherichia coli
(1997-07-31)
Tseng, CP
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Yu, CC
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Hwang, SM
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交大名義發表
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National Chiao Tung University
Reactions of phenol sulfotransferase with nucleotides
(1997-07-31)
Yang, YS
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Lin, ES
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生物科技學系
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Department of Biological Science and Technology
Reactions of phenol sulfotransferase with nucleotides
(1997-07-31)
Yang, YS
;
Lin, ES
;
生物科技學系
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Department of Biological Science and Technology
A multicasting solution for ATM video applications
(1997-08-01)
Tsai, JM
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Fang, HH
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Lee, CY
;
交大名義發表
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電子工程學系及電子研究所
This paper presents a multicasting solution for shared-buffer ATM switch, The cell duplicating function is performed by a one-to-many modified demur circuit, A shared multicast server is used to translate input multicast cells to find destination ports and corresponding routing information, By using link-list based ring structure, the multicast server can provide high speed (5 ns to search entry in 256-entry block in 0.8-mu m CMOS process) and cascadable multicast translating function, In addition, the channel complexity of multipoint-to-multipoint multicast applications can be reduced to N channels per N users. The shared-buffer controller is modified by adding controlling and scheduling functions for multicasting queues to process the multicast feature. Finally with the aid of the quality of service (QoS) management, this proposed solution provides multi-QoS for multicast cells to meet the needs of various video applications.
Thickness dependence of magnetic force acting on a magnetic dipole over a type-II superconducting thin film
(1997-08-01)
Yang, TJ
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Wei, JC
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Chen, JL
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Horng, L
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電子物理學系
The thickness dependence of the magnetic force acting on a point magnetic dipole over a superconducting thin film in the mixed state with a single vortex line is calculated by London theory. The magnetic force is decomposed into two parts, vertical and lateral components. Both vertical and lateral force components approach to the saturated value with increasing thickness when the thickness is much larger than the London penetration depth. A single vortex created in the thin film by the field of the magnetic dipole is also considered. The thickness dependence of the critical position of the point dipole for creating the first vortex line in the thin film is exploited and derived.
The design of a hybrid filter bank for the psychoacoustic model in ISO/MPEG phases 1,2 audio encoder
(1997-08-01)
Liu, CM
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Lee, WC
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資訊工程學系
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Department of Computer Science
The ISO/MPEG phases 1 and 2 audio compression are receiving a wide range of applications. In the encoding process of MPEG, the psychoacoustic model exploits audio irrelevancy which is the key role to achieve high compression ratio without losing audio quality. However, the Fourier transform (FT) which has been used by the two psychoacoustic models suggested in standard draft requires high computational complexity, and hence leads to high hardware and software cost for real-time applications. This paper presents a new design named the hybrid filter bank to replace the FT. The hybrid filter bank can be integrated with the psychoacoustic models and provides a much lower complexity than the FT. Also, this paper shows that the hybrid filter is more suitable for the stereo coding and hence can provide a better quality for the intensity stereo coding, which is the key technology for the MPEG 1 to achieve near transparent quality lower than 96x2 kbits for two stereo channels.
Objective image quality measure for block-based DCT coding
(1997-08-01)
Liu, CM
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Lin, JY
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Wu, KG
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Wang, CN
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交大名義發表
The block-based discrete cosine transform (DCT) coding has been widely adopted in image or video compression standards, such as JPEG and MPEG. Such type of coding will produce a noticeable artifact known as the blocking effect at very low bit rate applications. In the literature, there have been various postprocessing methods proposed to reduce the blacking effect. However, there is no suitable objective criterion evaluating the effectiveness of these various methods. This paper presents a new objective measure evaluating the postprocessing methods. The proposed measure also provides an analytical result on the underlying sources of artifacts.
Stability and chaotic dynamics of a rate gyro with feedback control
(1997-08-01)
Ge, ZM
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Chen, HH
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機械工程學系
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Department of Mechanical Engineering
An analysis is presented of a single-axis rate gyro subjected to linear feedback control mounted on a space vehicle that is spinning with uncertain angular velocity w(Z)(t) about its spin of the gyro. The stability of the nonlinear nonautonomous system is investigated by Liapunov stability and instability theorems. Bs the electrical Dime constant is much smaller than the mechanical time constant, the full singularly perturbed system is obtained. We study the stability of the system by forming a Liapunov function candidate as a linear combination of the Liapunov functions for the reduced and boundary-layer systems. When the perturbation near angular velocity w(Z)(t) of the space vehicle is harmonic, the feedback control system reduces to a planar system of parametrical excitation by the singular perturbation theory. Using the Melnikov technique, we can give criteria for the existence of chaos in the gyro motion. The numerical results, in which the existence of chaos is demonstrated, are presented in the form of phase plane, Poincare maps, bifurcation diagrams and Lyapunov exponents.
Three-dimensional finite element analysis of sheet-metal bending with complex die geometry
(1997-08-01)
Chou, IN
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Hung, CH
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機械工程學系
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Department of Mechanical Engineering
The purpose of this research was to and manufacturing processing conditions that would prevent the occurrence of fractures in a sheet-metal bending product. The finite element code ABAQUS was used to analyze the tensile strain at the particular point where fractures frequently occur. First an optimal combination of factors was sought using the method of controlling parameters. The analysis showed that the three factors, r(2), r(4), and the coefficient of friction, which are typical controlling factors, cannot be used to reduce the tensile strain at the critical point efficiently. A preform design was then applied to solve the problem of fracturing. By using a two-step bending operation, we successfully moved the highest tensile strain away from the critical point and also reduced the magnitude of this strain.
The application of Petri nets to failure analysis
(1997-08-01)
Liu, TS
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Chiou, SB
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交大名義發表
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機械工程學系
;
National Chiao Tung University
Unlike the technique of fault tree analysis that has been widely applied to system failure analysis in reliability engineering, this study presents a Petri net approach to failure analysis. It is essentially a graphical method for describing relations between conditions and events. The use of Petri nets in failure analysis enables to replace logic gate functions in fault trees, efficiently obtain minimal cut sets, and absorb models. It is demonstrated that for failure analysis Petri nets are more efficient than fault trees. In addition, this study devises an alternative; namely, a trapezoidal graph method in order to account for failure scenarios. Examples validate this novel method in dealing with failure analysis. (C) 1997 Elsevier Science Limited.
Internetting connectionless data networks with a wide area public ATM network
(1997-08-01)
Tsai, IF
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Jan, RH
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資訊工程學系
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Department of Computer Science
Connectionless data services on ATM-based B-ISDN can be realized directly by means of the connectionless service function which is provided in connectionless servers. In this paper, we consider how to locate a certain amount of connectionless servers among the switching nodes in a public ATM network for the internetworking of connectionless data networks. The problem is formulated as a network optimization problem which is similar to the p-median problem. Two algorithms, one based on the greedy method and the other using branch-and-bound strategy, are presented to determine the locations of connectionless servers. By finding the optimal locations of connectionless servers, an optimal virtual overlay network which has minimized total transport costs for the connectionless data traffics can be constructed. (C) Elsevier Science B.V.
Hybrid-damped resolved-acceleration control for manipulators
(1997-08-01)
Wu, SL
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Lin, SK
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交大名義發表
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電控工程研究所
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National Chiao Tung University
The singularity problem of the resolved-acceleration control scheme can be solved by the damped least-squares method. This approach, however, does suffer from one serious drawback: oscillations of the end-effector when the target is outside the workspace and self-motion of the manipulator when it is at the orientation degeneracy. In this paper, we present a hybrid-damped resolved-acceleration control scheme (HDRAC), which is capable of damping both the accelerations and the velocities to overcome this drawback. The main advantage of the present approach is that the control system need not plan the path to avoid the infeasible region of the manipulator, since the controller will automatically command the end-effector to move along the boundary of the workspace with a minimum trajectory error. Thus this approach renders the resolved-acceleration control scheme a much more practical control for the industry. The stability of the proposed control scheme is also proved in this paper. Incorporated with the concept of the degenerated-direction damped least-squares method (DDDLSM), this new control scheme can also apply only to the degenerated directions, which scheme is simulated on the PUMA 560 manipulator to verify its usefulness. (C) 1997 John Wiley & Sons, Inc.
Study of the acoustic feedback problem of active noise control by using the l(1) and l(2) vector space optimization approaches
(1997-08-01)
Bai, MSR
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Wu, TY
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交大名義發表
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機械工程學系
;
National Chiao Tung University
This study attempts to explore the acoustic feedback problem that is frequently encountered in feedforward active noise control (ANC) structure from the standpoint of control theories. The analysis is carried out on the basis of the Youla's parametrization and the l(1)-norm and l(2)-norm vector space optimization. The ANC problem is formulated as a model matching procedure and is solved via linear programming in the dual vector space. These methods alleviate the problems caused by the nonminimum phase (NMP) zeros of the cancellation path. The ANC algorithms are implemented by using a digital signal processor. Various types of noises were chosen for validating the developed algorithms. The proposed methods are also compared with the well-known filtered-u least-mean square (FULMS) method, The experimental results show that the acoustic feedback problem significantly degrades the performance and stability of the ANC system regardless which method is used. Insights into the difficulties due to acoustic feedback are addressed along the line of control theories. (C) 1997 Acoustical Society of America.
呢喃
(1997-08-01)
管管
An adaptive neural fuzzy filter and its applications
(1997-08-01)
Lin, CT
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Juang, CF
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交大名義發表
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電控工程研究所
;
National Chiao Tung University
A new kind of nonlinear adaptive filter, the adaptive neural fuzzy filter (ANFF), based upon a neural network's learning ability and fuzzy if-then rule structure, is proposed in this paper, The ANFF is inherently a feedforward multilayered connectionist network which can learn by itself according to numerical training data or expert knowledge represented by fuzzy if-then rules, The adaptation here includes the construction of fuzzy if-then rules (structure learning), and the tuning of the free parameters of membership functions (parameter learning), In the structure learning phase, fuzzy rules are found based on the matching of input-output clusters, In the parameter learning phase, a backpropagation-like adaptation algorithm is developed to minimize the output error, There are no hidden nodes (i.e., no membership functions and fuzzy rules) initially, and both the structure learning and parameter learning are performed concurrently as the adaptation proceeds, However, if some linguistic information about the design of the filter is available, such knowledge can be put into the ANFF to form an initial structure with hidden nodes, Two major advantages of the ANFF can thus be seen: 1) a priori knowledge can be incorporated into the ANFF which makes the fusion of numerical data and linguistic information in the filter possible; and 2) no predetermination, like the number of hidden nodes, must be given, since the ANFF can find its optimal structure and parameters automatically. Moreover, in contrast to traditional fuzzy systems where the input-output spaces are partitioned as grid type causing the combinatorial growing of fuzzy rules as the input-output dimensions increase, irregular partitions are done in the ANFF according to the distribution of training data so fewer fuzzy rules will be generated, To demonstrate the performance of the ANFF, two applications, the nonlinear channel equalization and the adaptive noise cancellation, are simulated, Efficiency and advantages of the ANFF are verified by these simulations and comparisons.
呢喃
(1997-08-01)
管管
Improvement of water-related hot-carrier reliability by optimizing the plasma-enhanced tetra-ethoxysilane deposition process
(1997-08-01)
Lin, YM
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Jang, SM
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Yu, CH
;
Lei, TF
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電子工程學系及電子研究所
As-deposited, steam-exposed O-3-tetra-ethoxysilane (TEOS)-based intermetallic dielectric were characterized according to the LR-absorption spectra. The plasma-enhanced-TEOS films investigated here were formed by mixed-frequency plasma processes and differentiated by reaction oxidizers and/or plasma powers. Increasing stress and nitrogen or oxygen concentrations improved the moisture resistance of PE-TEOS oxide films. In addition to the moisture resistance of PE-TEOS films, another factor affecting hot-carrier robustness is the maximum thickness of the underlayer for O-3-TEOS films, which is limited by their conformity The integrated intermetallic dielectrics were evaluated by constant-current and hot-carrier stressing. In obtaining the best device reliability, a trade-off exists between moisture resistance, gapfilling capacity of the PE-TEOS underlayer, and plasma damage. Our results indicate that an O-2-rich, PE-TEOS film with a mechanical stress of 3 x 10(9) dyn/cm(2) is the optimum.
Multiple access in the presence of optical-beat and co-channel interference using Walsh-code-based synchronized CDMA technique
(1997-08-01)
Hsiao, CC
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Wang, BH
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Way, WI
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電信工程研究所
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Institute of Communications Engineering
We experimentally demonstrated the feasibility of using Walsh-code-hased synchronized code-division-multiple access (S-CDMA) technique to achieve multiple access in the presence of optical-beat interference (OBI), This multiple access technique can, thus, be applied to WDMA networks using subcarrier-based common wavelength signaling, or PON's which generally do not have wavelength control on uplink laser diodes.
Graphical method for the determination of the complex NMR shift and equilibrium constant for a hetero-association accompanying self-associations
(1997-08-01)
Lin, CC
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Fang, CY
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Kao, DY
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Chen, JS
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應用化學系
We describe a novel graphical method which, in conjunction with the previously proposed graphical determination of mono;ner shift, dimer shift, and dimerization constant for self-association, allows us to determine the complex shift and equilibrium constant for a hetero-association, A + B reversible arrow AB, accompanying self-associations, A + A reversible arrow A(2), and B + B reversible arrow B-2. The merit of the new method includes the removal of the restrictions imposed on the conventional Benesi-Hildebrand (B-H) plot: (1) that the concentration of one component must be much less than that of the other; (2) that there be no accompanying self-association, The simultaneous equilibrium of the self-association of 2-pyrrolidone (A) and that of 4-methyl-alpha-pyrrolidone (B) and the hetero-association between A and B in acetonitrile-d(3) at 25 degrees C is studied. The inappropriateness of the B-H plot in dealing with this case is also pointed out.
Amorphouslike chemical vapor deposited tungsten diffusion barrier for copper metallization and effects of nitrogen addition
(1997-08-01)
Chang, KM
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Yeh, TH
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Deng, IC
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Shih, CW
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電子工程學系及電子研究所
In this article, we propose an amorphouslike chemical vapor deposited tungsten (CVD-W) thin him as a diffusion barrier for copper metallization. Experimental results gave no evidence of interdiffusion and structural change for Cu/amorphouslike CVD-W/Si samples annealed up to 675 degrees C for 30 min in N-2. At higher temperatures (700 degrees C), Cu penetration results in the formation of eta ''-Cu3Si precipitates at the CVD-W/Si interface. This is due to the crystallization of the amorphouslike CVD-W film above 650 degrees C, rendering the grain-boundary structure and, hence, fast pathways for Cu diffusion. The Cu/amorphouslike CVD-W/p(+)n diodes, thus, sustain large increases in reverse leakage current. In addition, the effects of nitrogen addition by using an in situ nitridation on the amorphouslike CVD-W film are also discussed. The effectiveness of the nitrided barrier is attributed to the blocking of the grain boundaries in the tungsten film by nitrogen atoms. This slows down Cu diffusion significantly. Physical and chemical analyses indicate that interfaces in the Cu/WNx/W/Si multilayer maintain their integrity while the annealing is carried out at 750 degrees C. Moreover, the reverse leakage current densities of Cu/WNx/W/p(+)n diodes remain at 10(-7) A/cm(2) after 725 degrees C annealing. (C) 1997 American Institute of Physics.