Browsing by Author "Wu, SJ"

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A new insight into the degradation mechanisms of various mobility-enhanced CMOS devices with different substrate engineering
(2005)
Chung, SS
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Liu, YR
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Wu, SJ
;
Lai, CS
;
Liu, YC
In this paper, the difference in degradation mechanism for different substrate engineered CMOS devices has been reported for the first time. These two different substrate engineering includes hybrid substrate engineering, with (100) and (110) orientations, and strained-Si devices. Different mechanisms are responsible for these two different mobility enhancement schemes. For strained-Si devices, it shows that the dominant mechanism for HC(Hot Carrier) and NBT (Negative Bias Temperature) degradations is attributed to the lateral electric field resulting from the mobility enhancement. While for (110)/(100) substrate engineered devices, the dominant mechanism is due to the dangling bond of the surface. In other words, for (I I 0)/(l 00) substrate, the device degradation is weakly dependent on the mobility enhancement while largely dependent on the bond strength. Finally, the difference in temperature dependence of HC and NBT has also been observed for both strained-Si and (110)/(100) substrate devices. Sophisticated measurement techniques, charge pumping (CP) and gated-diode (GD) measurement, have been employed to understand these device mechanisms. These results provide a guideline for the device design and the understanding of related reliabilities in the popular strained-Si and hybrid substrate technology CMOS devices.
Application of fuzzy sets theory in process data filtering
(2003)
Chiang, HH
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Wu, SJ
;
Lee, TT
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電控工程研究所
;
Institute of Electrical and Control Engineering
introduced and applied to the problems of signal restoration. A fuzzy approach for system identification and state estimation is developed. The estimated values obtained from the fuzzy model are in the form of fuzzy numbers which present the possibility of the system structure. Both L-R and symmetric triangular type membership functions are employed to derive the fuzzy-data based estimator (FBE). Illustrative examples with white and color noise are provided to demonstrate the applicability and effectiveness of the developed FBE. Comparisons between the FBE and various modified Kalman filter are also included.
Application of neural-fuzzy modeling and optimal fuzzy controller for nonlinear magnetic bearing systems
(2003)
Yu, SS
;
Wu, SJ
;
Lee, TT
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電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper we apply a new approach, called optimal fizzy control based on linear TS type fuzzy model, to deal with nonlinear magnetic bearing systems. The linear TS type fuzzy model is used to represent the nonlinear plant To obtain the linear TS fuzzy model, we use linear self-constructing neural fuzzy inference network(linear SONFIN) to model the nonlinear system. Once the TS fuzzy model of the magnetic bearing system is obtained, the optimal fuzzy controller can be applied if the system is completely controllable and observable. Simulation results show that the proposed optimal fuzzy controller can operate in widely range of shaft position.
Bayesian inference for Rayleigh distribution under progressive censored sample
(2006-05-01)
Wu, SJ
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Chen, DH
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Chen, ST
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
It is often the case that some information is available on the parameter of failure time distributions from previous experiments or analyses of failure time data. The Bayesian approach provides the methodology for incorporation of previous information with the current data. In this paper, given a progressively type 11 censored sample from a Rayleigh distribution, Bayesian estimators and credible intervals are obtained for the parameter and reliability function. We also derive the Bayes predictive estimator and highest posterior density prediction interval for future observations. Two numerical examples are presented for illustration and some simulation study and comparisons are performed. Copyright (C) 2006 John Wiley & Sons. Ltd.
Comment on "discrete-time optimal fuzzy controller design: Global concept approach" - Reply
(2005-04-01)
Wu, SJ
;
Lin, CT
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電控工程研究所
;
Institute of Electrical and Control Engineering
Continuous time-invariant optimal fuzzy tracker design based on local concept approach
(2000)
Wu, SJ
;
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we propose a global optimal fuzzy tracking controller for continuous time-invariant fuzzy tracking system to trace the moving or model-following target under infinite-horizon (time) quadratic performance index. We also demonstrate that the stability of the closed-loop fuzzy tracking systems can be ensured by the designed optimal fuzzy tracking controllers. One example is given to illustrate the proposed optimal fuzzy tracker design scheme and to show the proved stability property.
Discrete-time optimal fuzzy controller design: Global concept approach
(2002-02-01)
Wu, SJ
;
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we propose a systematic and theoretically sound way to design a global optimal discrete-time fuzzy controller to control and stabilize a nonlinear discrete-time fuzzy system with finite or infinite horizon (time). A linear-like global system representation of discrete-time fuzzy system is first proposed by viewing a discrete-time fuzzy system in global concept and unifying the individual matrices into synthetical matrices. Then, based on this kind of system representation, the discrete-time optimal fuzzy control law which can achieve global minimum effect is developed theoretically. A nonlinear two-point-boundary-value-problem (TPBVP) is derived as the necessary and sufficient condition for the nonlinear quadratic optimal control problem. To simplify the computation, a multistage decomposition of optimization scheme is proposed and then a segmental recursive Riccati-like equation is derived. Moreover, in the case of time-invariant fuzzy systems, we show that the optimal controller can be obtained by just solving discrete-time algebraic Riccati-like equations. Grounding on this, several fascinating characteristics of the resultant closed-loop fuzzy system can be elicited easily. The stability of the closed-loop fuzzy system can be ensured by the designed optimal fuzzy controller. The optimal closed-loop fuzzy system can not only be guarantee to be exponentially stable, but also be stabilized to any desired degree. Also, the total energy of system output is absolutely finite. Moreover, the resultant closed-loop fuzzy system possesses an infinite gain margin; that is, its stability is guaranteed no matter how large the feedback gain becomes. An example is given to illustrate the proposed optimal fuzzy controller design approach and to demonstrate the proved stability properties.
Fuzzy approach for disturbance reduction
(2003)
Chiang, HH
;
Wu, SJ
;
Lee, TT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The basic principles of the fuzzy set theory are applied to the signal restoration problems. The estimated values obtained from the fuzzy model are in the form of fuzzy numbers which present the possibility of the system structure. Both L-R and symmetric triangular type membership functions are employed to derive the fuzzy disturbance reduction. The quarter-car semi-active suspension system with unknown disturbance caused by roughness of road is provided to demonstrate the applicability and effectiveness of the proposed fuzzy algorithm in disturbance reduction problem.
Global optimal fuzzy tracker design based on local concept approach
(2002-04-01)
Wu, SJ
;
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we propose a global optimal fuzzy tracking controller, implemented by fuzzily blending the individual local fuzzy tracking laws, for continuous and discrete-time fuzzy systems with the aim of solving, respectively, the continuous and discrete-time quadratic tracking problems with moving or model-following targets under finite or infinite horizon (time). The differential or recursive Riccati equations, and more, the differential or difference equations in tracing the variation of the target are derived. Moreover, in the case of time-invariant fuzzy tracking systems, we show that the optimal tracking controller can be obtained by just solving algebraic Riccati equations and algebraic matrix equations. Grounding on this, several fascinating characteristics of the resultant closed-loop continuous or discrete time-invariant fuzzy tracking systems can be elicited easily. The stability of both closed-loop fuzzy tracking systems can be ensured by the designed optimal fuzzy tracking controllers. The optimal closed-loop fuzzy tracking systems cannot only be guaranteed to be exponentially stable, but also be stabilized to any desired degree. Moreover, the resulting closed-loop fuzzy tracking systems possess infinite gain margin; that is, their stability is guaranteed no matter how large the feedback gain becomes. Two examples are given to illustrate the performance of the proposed optimal fuzzy tracker design schemes and to demonstrate the proved stability properties.
Identification and stochastic generation of representative rainfall temporal patterns in Hong Kong territory
(2006-04-01)
Wu, SJ
;
Yang, JC
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Tung, YK
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土木工程學系
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Department of Civil Engineering
In hydrosystem engineering design and analysis, temporal pattern for rainfall events of interest is often required. In this paper, statistical cluster analysis of dimensionless rainfall pattern is applied to identify representative temporal rainfall patterns typically occurred in Hong Kong Territory. For purpose of selecting an appropriate rainfall pattern in engineering applications, factors affecting the occurrence of different rainfall patterns are examined by statistical contingency tables analysis through which the inter-dependence of the occurrence frequency of rainfall patterns with respect to geographical location, rainfall duration and depth, and seasonality is investigated. Furthermore, due to inherent variability of rainfall mass curves or hyetographs within each classified rainfall pattern, a practical procedure to probabilistically generate plausible rainfall patterns is described. The procedure preserves the inherent stochastic features of random dimensionless rainfall hyetograph ordinates, which in general are correlated non-normal multivariate compositional variables.
Microstructural evolution and formation of highly c-axis-oriented aluminum nitride films by reactively magnetron sputtering deposition
(2005-04-01)
Liu, WJ
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Wu, SJ
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Chen, CM
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Lai, YC
;
Chuang, CH
Highly (0 0 2) c-axis-oriented AlN films have been successfully deposited on Ti/Si substrates using reactive magnetron radio frequency (RF) sputtering deposition and ideal AlN films could be obtained by fine-tuning the parameters at pressure 5Pa, temperature of 250 degrees C, and N-2 ratio 85%. The detailed layer-by-layer microstructure of AlN films deposited on Ti/Si substrate consists of TiO2 thin film, amorphous layer without Al2O3 particles, transition layer, and the columnar (0 0 2) e-axis preferred orientation layer. AlN films possessing a higher deposition rate to form an amorphous layer in the initial deposition stage will result in the lower deposition rate to form following transition and columnar preferred orientation textures. Therefore, we strongly suggest adopting a two-step deposition method, that is, use lower deposition rate to form preferred orientation layers and then a higher deposition rate to form preferred orientation textures. (c) 2004 Elsevier B.V. All rights reserved.
Minimum-energy neural-fuzzy approach for current/voltage-controlled electromagnetic suspension system
(2003)
Chang, YC
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Wu, SJ
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Lee, TT
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電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, the electromagnetic suspension system is modeled as a neural-based linear T-S fuzzy system, and then the optimal fuzzy control design scheme is proposed to control the current and voltage-controlled system with minimum current and voltage consumption, respectively. The proposed linear self-constructing neural fuzzy inference network is a six layer neural network (linear SONFIN) modified from the well-known SONFIN network, which can construct a linear T-S fuzzy model of the system just by the input and output (I/O) information. Based on the linear T-S model, we can construct the optimal fuzzy control scheme to efficiently regulate the highly nonlinear, complex and uncertain electromagnetic suspension system to the equilibrium state.
Neural-network-based optimal fuzzy controller design for nonlinear systems
(2005-09-01)
Wu, SJ
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Chiang, HH
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Lin, HT
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Lee, TT
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電控工程研究所
A neural-learning fuzzy technique is proposed for T-S fuzzy-model identification of model-free physical systems. Further, an algorithm with a defined modelling index is proposed to integrate and to guarantee that the proposed neural-based optimal fuzzy controller can stabilize physical systems; the modelling index is defined to denote the modelling-error evolution, and to ensure that the training data for neural learning can describe the physical system behavior very well; the algorithm, which integrates the neural-based fuzzy modelling and optimal fuzzy controlling process, can implement off-line modelling and on-line optimal control for model-free physical systems. The neural-fuzzy inference network is a self-organizing inference system to learn fuzzy membership functions and fuzzy-subsystems' parameters as data feeding in. Based on the generated T-S fuzzy models for the continuous mass-spring-damper system and Chua's chaotic circuit, discrete-time model car system and articulated vehicle, their corresponding fuzzy controllers are formulated from both local-concept and global-concept fuzzy approach, respectively. The simulation results demonstrate the performance of the proposed neural-based fuzzy modelling technique and of the integrated algorithm of neural-based optimal fuzzy control structure. (c) 2005 Elsevier B.V. All rights reserved.
Optimal fuzzy control of radial active magnetic bearing systems
(2003)
Yu, SS
;
Wu, SJ
;
Lee, TT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, a neural-fuzzy approach to develop the optimal fuzzy control of a highly nonlinear radial current-controlled active magnetic bearing (AMB) systems is proposed. A linear self-constructing neural fuzzy inference network is proposed to neural-fuzzy modeling the radial current-controlled AMB system first. Then, the corresponding optimal fuzzy control design scheme is obtained to stabilize the AMB system with minimize current consumption. Simulation results show that the proposed optimal fuzzy controller can operate in widely range of shaft position.
Optimal fuzzy controller design in continuous fuzzy system: Global concept approach
(2000-12-01)
Wu, SJ
;
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we propose a systematic and theoretically sound way to design a global optimal fuzzy controller to control and stabilize a continuous fuzzy system with free- or fixed-end point under finite or infinite horizon (time), A linear-like global system representation of continuous fuzzy system is first proposed by viewing a continuous fuzzy system in global concept and unifying the individual matrices into synthetical matrices. Based on this, the optimal control law which can achieve global minimum effect is developed theoretically. The nonlinear segmental two-point boundary-value problem (TPBVP) is derived for the finite-horizon problem and a forward Riccati-like differential equation (DE) for the infinite-horizon problem. To further simplify the computation, a segmental Riccati-like DE is derived in solving the finite- or infinite-horizon issues. Moreover, in the case of time-invariant fuzzy systems, we show that the optimal controller can be obtained by Just solving algebraic Riccati-like equations. Grounding on this, several fascinating characteristics of the resultant closed-loop fuzzy system can be elicited easily. The stability of the closed-loop fuzzy system can be ensured by the designed optimal fuzzy controller. The optimal closed-loop fuzzy system cannot only be guaranteed to be exponentially stable, but also be stabilized to any desired degree. Also, the total energy of system output is absolutely finite. Moreover, the resultant closed-loop fuzzy system possesses an infinite gain margin; that is, its stability is guaranteed no matter how large the feedback gain becomes. An example is given to illustrate the proposed optimal fuzzy controller design approach and to demonstrate the proved stability properties.
Optimal fuzzy controller design: Local concept approach
(2000-04-01)
Wu, SJ
;
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we present a global optimal and stable fuzzy controller design method for both continuous- and discrete-time fuzzy systems under both finite and infinite horizons. First, a sufficient condition is proposed which indicates that the global optimal effect can be achieved by the fuzzily combined local optimal controllers. Based on this sufficient condition, we derive a local concept approach to designing the optimal fuzzy controller by applying traditional linear optimal control theory, The stability of the entire closed-loop continuous fuzzy system can be ensured by the designed optimal fuzzy controller. The optimal feedback continuous fuzzy system can not only be guaranteed to be exponentially stable, but also be stabilized to any desired degree. Also, the total energy of system output is absolutely finite. Moreover, the resultant feedback continuous fuzzy system possesses an infinite gain margin; that is, its stability is guaranteed no matter how large the feedback gain becomes, Two examples are given to illustrate the proposed optimal fuzzy controller design approach and to demonstrate the proved stability properties.
Risk analysis of reservoir level during rehabilitation
(2000)
Wu, SJ
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Yang, JC
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Tung, YK
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土木工程學系
;
Department of Civil Engineering
After five decades of service since 1953, the storage capacity of Ah-gong-dein reservoir in Taiwan has been reduced by about 71% due to accumulated sedimentation. Its ability to serve flood control function has been greatly compromised. The Taiwan Department of Water Resources currently is undertaking measures to vitalize its flood control function over an eight-year period. The paper addresses probabilistic behavior of reservoir surface level during the rehabilitation period. In particular, randomness of monthly rainfall amounts is considered in developing function relationship between monthly probability of water surface elevation exceeding certain target level and various factors. Information such as these is useful to examine the implications of proposed rehabilitation schemes on overtopping risk and to monitor the required revitalization progress and reservoir storage condition.