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Start date: 1980End date: 1999

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    BRM technique for space vector decomposition reactive power of SPIM
    (1999-12-01)
    Tipsuwanporn, V.
    ;
    Cheevasuvit, F.
    This research paper proposes the controlling technique of Single Phase Induction Motor (SPIM) by Binary Rate Modulation (BRM). The BRM composes of 8 independent patterns, these patterns can be linearly combined into 255 pattern forms, then transmit to control motor speed. Applying this technique along with vector space will result in power factor increasing and reactive power decreasing. When load is at threshold state it can be brought to the steady state condition at short instant, consequently the capacity and efficiency will be improved.
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    Analysis of steerable active slot array applicator
    (1999-12-01)
    Krairiksh, M.
    ;
    Thongsopa, C.
    ;
    Srimoon, D.
    ;
    Mearnchu, A.
    This paper analyzes temperature distribution of a steerable active slot array applicator in terms of slot separation and injecting signal to find the appropriate condition that provides a wide effective area. This result is useful in the design of an applicator for a large area application such as chest wall.
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    Adaptive fuzzy PI controller for speed of separately excited DC motor
    (1999-12-01)
    Tunyasrirut, S.
    ;
    Ngamwiwit, J.
    ;
    Furuya, T.
    This paper presents a design of adaptive fuzzy PI controller to control the speed of separately excited DC motor by self-tuning. The speed of motor can be changed by controlling the armature and field voltages. In this paper, the adaptive fuzzy PI controller is designed to control the armature voltage while the field voltage is fixed as a constant. The fuzzy system tunes the gains of the PI controller according to error and change of error of the speed control system to meet the step response specifications of the motor speed. The experimental results show that the step responses of the speed of the DC motor controlled by the adaptive fuzzy PI controller have step responses with small overshoot when compared to the usual PI cascade controller. That is, the proposed controller gives the controlled system has small overshoot and zero steady-state error when the reference speed is 2000 rpm at no load, half load and full load. The effect of the applied step full load and released load at the steady state is also rapidly rejected.
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    BRM fast response DC motor speed control
    (1999-12-01)
    Tipsuwanporn, V.
    ;
    Cheevasuvit, F.
    ;
    Piyarat, W.
    ;
    Siribanchachai, W.
    ;
    Paraken, Y.
    The paper presents, hithtero contribute the DC motor control by Binary Rate Modulation (BRM). The 8 bit binary rate are controlled by 8051 which inturn generate BRM by PI(Proportional Integral Controller). The BRM method is efficient to control the supplied power with appropriate speed. BRM method has low ripple, usually less than 5%, consequently, less noise with fast speed response when load changes.
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    Temperature-insensitive voltage-to-current converter and its applications
    (1999-12-01)
    Surakampontorn, Wanlop
    A novel voltage-to-current (V/I) converter circuit is proposed, which is based on an Operational Transconductance Amplifier (OTA) integrated circuit. The V/I transconductance gain is insensitive to temperature and the input differential voltage swing limitation of the OTA integrated circuit is alleviated. New circuits for the temperature-insensitive general-grounded resistance converter, instrumentation amplifier, electronically tunable gyrator, and analog multiplier are presented. Experimental and simulation results that demonstrate the performances of the V/I and its applications are also included.
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    SAR images speckle noise reduction by wavelet thresholding
    (1999-12-01)
    Thitimajshima, Punya
    This paper describes a method of speckle reduction in Synthetic Aperture Radar (SAR) images based on the wavelet transform. To deduce the problem of filtering the multiplicative noise to the case of an additive noise, the wavelet decomposition is performed on the logarithm of the image gray levels. A threshold value is estimated according to the noise variance and used for the soft-thresholding performed on all the high frequency subimages. The filtered logarithmic image is then obtained by reconstruction from the thresholded coefficients. The exponential function of this reconstructed image gives the final filtered image. Experimental results on JERS-1/SAR images showed that the proposed method results in a significant noise removal.
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    Fuzzy logic control for speed of wound rotor induction motor with slip energy recovery
    (1999-12-01)
    Tunyasrirut, Satean
    ;
    Kanchanathep, Attapol
    ;
    Ngamwiwit, Jongkol
    ;
    Furuya, Tadayoshi
    Fuzzy Logic control is considered for speed of wound rotor induction motors with slip energy recovery. The speed is limited at some range of sub-synchronous speed of the rotating magnetic field. Control speed by adjusting resistance value in the rotor circuit that occurs the efficiency of power are reduced, because of the slip energy is lost when it passes through the rotor resistance. The control system is designed to maintain efficiency of motor. Fuzzy logic control method is applied for self-tuning the system by keeping the speed constant and adjusting the rotor current appropriated to the load. The good transient response without overshoot can be obtained.
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    Edge detection in remote sensing images based on cluster information
    (1999-12-01)
    Chumsamrong, Warin
    ;
    Thitimajshima, Punya
    In this paper, a multispectral image edge detection algorithm is proposed based on the idea that uses global multispectral information to guide local gradient computation. The image is first segmented into a small number of clusters through a clustering algorithm. According to these clusters, a set of linear projection vectors are generated. For a given image, if n clusters are found, there are n(n-1)/2 possible projection vectors. Edge detection is performed by calculating gradient magnitudes separately on each channel. An appropriate projection vector is chosen for each pixel to maximize gradient magnitude. In this way, edges are treated as transitions from one cluster to another. The algorithm has been tested on JERS-1/OPS images, and the experimental results demonstrate its potential usefulness.
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    Wavelet-based texture analysis for SAR image classification
    (1999-12-01)
    Chumsamrong, Warin
    ;
    Thitimajshima, Punya
    ;
    Rangsanseri, Yuttapong
    In this paper, a novel method for SAR image classification based on stationary wavelet transform will be described. First, a SAR image is decomposed into 4 subbands using stationary wavelet transform. Each pixel is then represented by a 4-dimension vector whose components are taken from the wavelet subbands. The pixels are finally classified into a small set of categories by using a parametric supervised classification algorithm. The classification using this wavelet transform was successfully applied to a JERS-1/SAR image.
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    Fuzzy clustering of multispectral images based on integrated spectral and spatial features
    (1999-12-01)
    Rangsanseri, Yuttapong
    An unsupervised classification method in multispectral images based on a fuzzy clustering driven by integrated spectral and spatial features is presented. Spectral information can be obtained directly from pixel values in different frequency-band images, while spatial information can be extracted by mean of texture analysis. The images are spectrally decorrelated via the Karhunen-Loeve Transform (KLT). The resulting first principal component image is then exploited by applying the gray-level co-occurrence matrices. A fuzzy clustering approach is finally performed based on the features that combine both spectral and spatial information on the image. The results of applying the algorithm to an urban area image are illustrated.