Browsing by Author "CHAN, KK"

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A NEURAL NETWORK APPROACH TO MVDR BEAMFORMING PROBLEM
(1992-03-01)
CHANG, PR
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YANG, WH
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CHAN, KK
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交大名義發表
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電信工程研究所
A Hopfield-type neural network approach which leads to an analog circuit for implementing the real-time adaptive antenna array is presented. An optimal pattern of the array can be steered by updating the weights across the array in order to maximize the output signal-to-noise ratio (SNR). Furthermore, it is shown that the problem of adjusting the array weights can be characterized as a constrained quadratic nonlinear programming. Practically, the adjustment of settings is required to respond to a rapid time-varying environment. Many numerical algorithms have been developed for solving such problems using digital computers. The main disadvantage of these algorithms is that they generally converge slowly. To tackle this difficulty, a neural analog circuit solution is particularly attractive in real-time applications with minimization of a cost function subject to constraints. A novel Hopfield-type neural net with a number of graded-response neurons designed to perform the constrained quadratic nonlinear programming would lead to such a solution in a time determined by RC time constants, not by algorithmic time complexity. The constrained quadratic programming neural net has associated it with an energy function which the net always seeks to minimize. A fourth-order Runge-Kutta simulation is conducted to verify the performance of the proposed analog circuit. It shows that the circuit operates at a much higher speed than conventional techniques and the computation time of solving a linear array of 10 elements is about 0.1 ns for RC = 5 x 10(-9).
COMMENTS ON A NEURAL-NETWORK APPROACH TO MVDR BEAMFORMING PROBLEM - REPLY
(1993-09-01)
CHANG, PR
;
YANG, WH
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CHAN, KK
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交大名義發表
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電信工程研究所
COMPLEX-VALUED NEURAL-NETWORK FOR DIRECTION-OF-ARRIVAL ESTIMATION
(1994-03-31)
YANG, WH
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CHAN, KK
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CHANG, PR
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交大名義發表
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電信工程研究所
A complex-valued neural network for the implementation of a direction of arrival (DoA) estimator is presented. The network is based on the linear prediction method, with data processed fully in the complex domain. Simulation results are given to demonstrate the effectiveness of the network performances.
ON THE SPECTRAL THEORY OF WAVE-PROPAGATION IN A WEAKLY RANGE-DEPENDENT ENVIRONMENT
(1986-05-01)
CHAN, KK
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交大名義發表
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傳播研究所
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National Chiao Tung University
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Institute of Communication Studies
OPTIMAL BORESIGHT ERROR DESIGN OF RADOMES OF REVOLVING SYMMETRY
(1994-09-15)
HSU, F
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CHAN, KK
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CHANG, PR
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CHAO, SH
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電信工程研究所
An optimisation technique is applied to the design of three-dimensional radomes of revolving symmetry. A design example for an ogive radome is given. The best possible thickness profile of the radome is found and the boresight error is reduced significantly. Both B-spline modelling and polynomial modelling for the thickness profile are considered.
OPTIMIZATION OF 2-DIMENSIONAL RADOME BORESIGHT ERROR PERFORMANCE USING SIMULATED ANNEALING TECHNIQUE
(1993-09-01)
HSU, F
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CHANG, PR
;
CHAN, KK
;
交大名義發表
;
電信工程研究所
In this paper a systematic approach to radome design is presented. The problem is formulated as a global optimization procedure such that the radome performance is optimized by properly adjusting the thickness of the radome layer over the entire radome surface. In this approach the thickness profile is parameterized via B-splines representation. Simulated annealing technique is applied to finding the best thickness profile so that the maximum boresight error is reduced as small as possible over the entire range of the antenna look angle. A two-dimensional design example is given. The best possible thickness profile is found and the boresight error is reduced considerably compared to that due to a uniform layer. The method is general and can be applied without difficulty to other realistic three-dimensional radomes of arbitrary shapes.
PULSED FIELD DUE TO AN ELECTRIC-DIPOLE IN PRESENCE OF A PERFECTLY CONDUCTING WEDGE
(1977)
CHAN, KK
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FELSEN, LB
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交大名義發表
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National Chiao Tung University
TRANSIENT AND TIME-HARMONIC DYADIC GREEN-FUNCTIONS FOR A PERFECTLY CONDUCTING CONE
(1979)
CHAN, KK
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FELSEN, LB
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交大名義發表
;
National Chiao Tung University