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Full-Text Articles in Engineering

Training Fuzzy Systems With The Extended Kalman Filter, Daniel J. Simon Dec 2002

Training Fuzzy Systems With The Extended Kalman Filter, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

The generation of membership functions for fuzzy systems is a challenging problem. We show that for Mamdani-type fuzzy systems with correlation-product inference, centroid defuzzification, and triangular membership functions, optimizing the membership functions can be viewed as an identification problem for a nonlinear dynamic system. This identification problem can be solved with an extended Kalman filter. We describe the algorithm and compare it with gradient descent and with adaptive neuro-fuzzy inference system (ANFIS) based optimization of fuzzy membership functions. The methods discussed in this paper are illustrated on a fuzzy filter for motor winding current estimation, and are compared with Butterworth …


Training Radial Basis Neural Networks With The Extended Kalman Filter, Daniel J. Simon Oct 2002

Training Radial Basis Neural Networks With The Extended Kalman Filter, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Radial basis function (RBF) neural networks provide attractive possibilities for solving signal processing and pattern classification problems. Several algorithms have been proposed for choosing the RBF prototypes and training the network. The selection of the RBF prototypes and the network weights can be viewed as a system identification problem. As such, this paper proposes the use of the extended Kalman filter for the learning procedure. After the user chooses how many prototypes to include in the network, the Kalman filter simultaneously solves for the prototype vectors and the weight matrix. A decoupled extended Kalman filter is then proposed in order …


Sum Normal Optimization Of Fuzzy Membership Functions, Daniel J. Simon Aug 2002

Sum Normal Optimization Of Fuzzy Membership Functions, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Given a fuzzy logic system, how can we determine the membership functions that will result in the best performance? If we constrain the membership functions to a certain shape (e.g., triangles or trapezoids) then each membership function can be parameterized by a small number of variables and the membership optimization problem can be reduced to a parameter optimization problem. This is the approach that is typically taken, but it results in membership functions that are not (in general) sum normal. That is, the resulting membership function values do not add up to one at each point in the domain. This …


From Linear To Nonlinear Control Means: A Practical Progression, Zhiqiang Gao Apr 2002

From Linear To Nonlinear Control Means: A Practical Progression, Zhiqiang Gao

Electrical and Computer Engineering Faculty Publications

With the rapid advance of digital control hardware, it is time to take the simple but effective proportional-integral-derivative (PID) control technology to the next level of performance and robustness. For this purpose, a nonlinear PID and active disturbance rejection framework are introduced in this paper. It complements the existing theory in that (1) it actively and systematically explores the use of nonlinear control mechanisms for better performance, even for linear plants; (2) it represents a control strategy that is rather independent of mathematical models of the plants, thus achieving inherent robustness and reducing design complexity. Stability analysis, as well as …


A Stable Self-Tuning Fuzzy Logic Control System For Industrial Temperature Regulation, Zhiqiang Gao, Thomas A. Trautzsch, James G. Dawson Mar 2002

A Stable Self-Tuning Fuzzy Logic Control System For Industrial Temperature Regulation, Zhiqiang Gao, Thomas A. Trautzsch, James G. Dawson

Electrical and Computer Engineering Faculty Publications

A closed-loop control system incorporating fuzzy logic has been developed for a class of industrial temperature control problems. A unique fuzzy logic controller (FLC) structure with an efficient realization and a small rule base that can be easily implemented in existing industrial controllers was proposed. The potential of FLC in both software simulation and hardware test in an industrial setting was demonstrated. This includes compensating for thermo mass changes in the system, dealing with unknown and variable delays, operating at very different temperature set points without retuning, etc. It is achieved by implementing, in the FLC, a classical control strategy …


A 0.5 Μm Thick Polysilicon Schottky Diode With Rectification Ratio Of 10^6, Elena A. Guliants, Chunhai Ji, Young J. Song, Wayne A. Anderson Jan 2002

A 0.5 Μm Thick Polysilicon Schottky Diode With Rectification Ratio Of 10^6, Elena A. Guliants, Chunhai Ji, Young J. Song, Wayne A. Anderson

Electrical and Computer Engineering Faculty Publications

Polycrystalline Si films, 0.5-mm thick, were obtained as a result of metal-induced growth by sputtering from a Si target on 25 nm thick Ni prelayers at 525 °C. Silicon grew heteroepitaxially on the NiSi2 layer formed due to the reaction between the sputtered Si atoms and Ni. Schottky diodes were fabricated on the Si films by deposition of a Schottky metal on the front surface of the film while Ni disilicide provided an intimate ohmic contact at the back. A Pd/n-Si diode using an n-Si film annealed for 2 h at 700 °C in forming gas demonstrated a rectification ratio …


Self-Assembly Of Spatially Separated Silicon Structures By Si Heteroepitaxy On Ni Disilicide, Elena A. Guliants, Chunhai Ji, Wayne A. Anderson Jan 2002

Self-Assembly Of Spatially Separated Silicon Structures By Si Heteroepitaxy On Ni Disilicide, Elena A. Guliants, Chunhai Ji, Wayne A. Anderson

Electrical and Computer Engineering Faculty Publications

A nonlithographic approach to produce self-assembled spatially separated Si structures for nanoelectronic applications was developed, employing the metal-induced silicon growth. Densely packed Si whiskers, 500–800 nm thick and up to 2500 nm long, were obtained by magnetron sputtering of Si on a 25 nm thick Ni prelayer at 575 °C. The nucleation of the NiSi2 compound at the Ni–Si interface followed by the Si heteroepitaxy on the lattice-matched NiSi2 is suggested to be the driving force for the whisker formation.


Implementation Of A Si/Sic Hybrid Optically Controlled High-Power Switching Device, Prashant Bhadri, Kuntao Ye, Elena A. Guliants, Fred R. Beyette Jr. Jan 2002

Implementation Of A Si/Sic Hybrid Optically Controlled High-Power Switching Device, Prashant Bhadri, Kuntao Ye, Elena A. Guliants, Fred R. Beyette Jr.

Electrical and Computer Engineering Faculty Publications

The ever-increasing performance and economy of operation requirements placed on commercial and military transport aircraft are resulting in very complex systems. As a result, the use of fiber optic component technology has lead to high data throughput, immunity to EMI, reduced certification and maintenance costs and reduced weight features. In particular, in avionic systems, data integrity and high data rates are necessary for stable flight control. Fly-by-Light systems that use optical signals to actuate the flight control surfaces of an aircraft have been suggested as a solution to the EMI problem in avionic systems. Current fly-by-light systems are limited by …


Translation Of 'Balika Badhu: A Selected Anthology Of Bengali Short Stories', Monish Ranjan Chatterjee Jan 2002

Translation Of 'Balika Badhu: A Selected Anthology Of Bengali Short Stories', Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

This project, which began with the desire to render into English a rather long tale by Bimal Kar about five years ago, eventually grew into a considerably more extended compilation of Bengali short stories by 10 of the most well-known practitioners of that art since the heyday of Rabindranath Tagore. The collection is limited in many ways, not the least of which being that no woman writer has been included, and that it contains only a baker's dozen stories (if we count Bonophool's micro-stories collectively as one ) — a number pitifully small considering the vast and prolific field of …


Kalman Filtering With State Equality Constraints, Daniel J. Simon, Tien Li Chia Jan 2002

Kalman Filtering With State Equality Constraints, Daniel J. Simon, Tien Li Chia

Electrical and Computer Engineering Faculty Publications

Kalman filters are commonly used to estimate the states of a dynamic system. However, in the application of Kalman filters there is often known model or signal information that is either ignored or dealt with heuristically. For instance, constraints on state values (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. A rigorous analytic method of incorporating state equality constraints in the Kalman filter is developed. The constraints may be time varying. At each time step the unconstrained Kalman filter solution is projected onto the state …