Showing papers by "Chung Yuan Christian University published in 1998"

Adaptive fuzzy sliding-mode control for PM synchronous servo motor drives

Abstract: An adaptive fuzzy sliding-mode control system, which combines the merits of sliding-mode control, the fuzzy inference mechanism and the adaptive algorithm, is proposed. First a sliding-mode controller with an integral-operation switching surface is designed. Then a fuzzy sliding-mode controller is investigated in which a simple fuzzy inference mechanism is used to estimate the upper bound of uncertainties. The fuzzy inference mechanism with centre adaptation of membership functions is investigated to estimate the optimal bound of uncertainties. Position control of a permanent magnet synchronous servo motor drive using the proposed control strategies is illustrated.

High-pressure phase transitions in Zn 1 − x M x Se ( M = Cd , Fe, and Mn)

Abstract: Energy-dispersive x-ray diffraction was employed to study pressure-induced phase transitions in ${\mathrm{Zn}}_{0.84}{\mathrm{Fe}}_{0.16}$Se, ${\mathrm{Zn}}_{0.9}{\mathrm{Cd}}_{0.1}$Se, and ${\mathrm{Zn}}_{0.76}{\mathrm{Mn}}_{0.24}$Se crystals up to 21.0, 23.3, and 24.3 GPa, respectively. Our result shows that the $B3$ to $B1$ structure transitions for these crystals occurred at 11.4$\ifmmode\pm\else\textpm\fi{}$0.5, 9.5$\ifmmode\pm\else\textpm\fi{}$0.3, and 9.6$\ifmmode\pm\else\textpm\fi{}$0.5 GPa, respectively. Compared to the phase-transition pressure ${(P}_{t})$ of ZnSe (14.4 GPa), a reduction of about 3--5 GPa is exhibited in these ternary compounds. This reduction in phase-transition pressure $\ensuremath{\Delta}{P}_{t}$ in the ternary compounds suggests that the fractional volume change, $(\ensuremath{\Delta}{V/V}_{0})$, of the $B3\ensuremath{-}B1$ phase admixture might be the source of this reduction. Our results indicate that ${P}_{t}$ (with respect to the phase transition pressure 14.4 GPa of ZnSe) is related to the fractional volume change $(\ensuremath{\Delta}{V/V}_{0})$ by the expression ${P}_{t}$=[14.4003+0.1568$(\ensuremath{\Delta}{V/V}_{0})$-0.0281$(\ensuremath{\Delta}{V/V}_{0}{)}^{2}$] GPa.

A new short-term load forecasting approach using self-organizing fuzzy ARMAX models

Abstract: This paper proposes a new self-organizing model of fuzzy autoregressive moving average with exogenous input variables (FARMAX) for one day ahead hourly load forecasting of power systems To achieve the purpose of self-organizing the FARMAX model, identification of the fuzzy model is formulated as a combinatorial optimization problem Then a combined use of heuristics and evolutionary programming (EP) scheme is relied on to solve the problem of determining optimal number of input variables, best partition of fuzzy spaces and associated fuzzy membership functions The proposed approach is verified by using diverse types of practical load and weather data for Taiwan Power (Taipower) systems Comparisons are made of forecasting errors with the existing ARMAX model implemented by the commercial SAS package and an artificial neural networks (ANNs) method

Capability Index Using Principal Components Analysis

Abstract: Multivariate process capability indices have recently been developed to assess the capability of processes having multiple characteristics. When quality variables are related characteristics, analysis should be based on a multivariate statistical techni..

A PM synchronous servo motor drive with an on-line trained fuzzy neural network controller

Abstract: A permanent magnet (PM) synchronous servo motor drive with integral-proportional (IP) position controller and a proposed on-line trained fuzzy neural network (FNN) controller is introduced in this paper. First, an IP position controller is designed according to the estimated plant model to match the time-domain command tracking specifications. Then the resulting closed-loop tracking transfer function is used as the reference model, and an adaptive signal generated from the proposed FNN controller, whose membership functions and connective weights are trained on-line according to the model-following error of the states, is added to the control system to preserve a favorable model-following characteristics under various operating conditions.

Fast kNN classification algorithm based on partial distance search

Abstract: A new fast kNN classification algorithm is presented for texture and pattern recognition. The algorithm identifies the fat k closest vectors in the design set of a kNN classifier for each input vector by performing the partial distance search in the wavelet domain. Simulation results show that, without increasing the classification error rate, the algorithm requires only 12.94% of the computational time of the original kNN technique.

Novel sliding mode controller for synchronous motor drive

Abstract: A novel sliding mode controller with an integral-operation switching surface is proposed. Furthermore, an adaptive sliding mode controller is investigated, in which a simple adaptive algorithm is utilized to estimate the bound of uncertainties. The position control for a permanent magnet (PM) synchronous servo motor drive using the proposed control strategies is illustrated. The theoretical analysis and the theorems for the proposed sliding mode controllers are described in detail. Simulation and experimental results show that the proposed controllers provide high-performance dynamic characteristics and are robust with regard to plant parameter variations and external load disturbance.

Comparison of sliding-mode and fuzzy neural network control for motor-toggle servomechanism

Abstract: A comparative study of sliding-mode control and fuzzy neural network (FNN) control on the motor-toggle servomechanism is presented. The toggle mechanism is driven by a permanent-magnet synchronous servomotor. The rod and crank of the toggle mechanism are assumed to be rigid. First, Hamilton's principle and Lagrange multiplier method are applied to formulate the equation of motion. Then, based on the principles of the sliding-mode control, a robust controller is developed to control the position of a slider of the motor-toggle servomechanism. Furthermore, an FNN controller with adaptive learning rates is implemented to control the motor-toggle servomechanism for the comparison of control characteristics. Simulation and experimental results show that both the sliding-mode and FNN controllers provide high-performance dynamic characteristics and are robust with regard to parametric variations and external disturbances. Moreover, the FNN controller can result in small control effort without chattering.

Evaluating different footprints parameters as a predictor of arch height

Abstract: Some controversies still exist concerning the validity and efficacy of using footprint parameters to predict arch height. Some investigators have disputed the ability of using the footprint to characterize arch types, since factors other than arch height may contribute to the footprint. Chu and coworkers (1995) used a digital approach and included pressure information with AI, which they termed the modified arch index (MAI). Their results showed that significant correlation existed between the arch height and both the MAI (r=-0.71) and the AI (r=-0.70). The causes of the above-mentioned controversy have been believed to be due to errors introduced during the footprint acquisition and parameter extraction phases. The purpose of this study was to use the same digital approach as Chua to determine whether correlation existed between arch height and the other eight footprint parameters besides the MAI and AI. The objective of classifying foot arch type is to help people with abnormal foot structure prevent injury, and to help athletes enhance performance. The main purpose of footprint parameters is to provide an easily accessible and valid approach to reach this objective.

Influence of hydroxyapatite particle size on bone cell activities: An in vitro study

Abstract: Over the past decade, a large number of biomaterials have been proposed as artificial bone fillers for repairing bone defects. The material most widely used in clinical medicine is hydroxyapatite. The aim of our investigation was to study the effect of hydroxyapatite size mechanism on osteoblasts. The osteoblasts were cultured in vitro with 0.1% (1 mg/mL) of various sized hydroxyapatite particles (0.5-3.0, 37-63, 177-250, and 420-841 microm) for 1 h, 3 h, 1 day, 3 days, and 7 days. The results showed that adding hydroxyapatite particles to osteoblast cultures can significantly affect osteoblast cell count. Osteoblast populations decreased significantly. Osteoblast mean surface areas also changed significantly. Transforming growth factor-beta1 (TGF-beta1) concentrations in culture medium decreased significantly with the addition of hydroxyapatite particles. Prostaglandin E2 (PGE2) concentrations in medium increased significantly. The changes in TGF-beta1 and PGE2 concentration were more significant and persisted longer in smaller-particle groups. The inhibitory effects of hydroxyapatite particles on osteoblast cell cultures were mediated by the increased synthesis of PGE2. Caution should be exercised before using a hydroxyapatite product which could easily break down into fine particles.

Experimental evaluation of smart antenna system performance for wireless communications

Abstract: In wireless communications, smart antenna systems (or antenna arrays) can be used to suppress multipath fading with antenna diversity and to increase the system capacity by supporting multiple co-channel users in reception and transmission. This paper presents experimental results of diversity gain, interference cancellation, and mitigation of multipath fading obtained by using a smart antenna system in typical wireless scenarios. Also given are experimental results for the signal-to-interference ratio (SIR) of two moving users, comparing different beamforming algorithms in typical wireless scenarios. All of the experiments were performed using the 900-MHz smart antenna testbed at The University of Texas at Austin.

Study of amorphous tin oxide thin films for ISFET applications

Abstract: In this study, an amorphous tin oxide (SnO 2 ) obtained by thermal evaporation was used as a pH-sensitive material for pH-ISFETs. Capacitance–voltage (C–V) curves of the EIS diode were used to evaluate pH response of SnO 2 thin film. Subsequently, SnO 2 /SiO 2 gate ISFET was fabricated and pH sensitivity was determined through a shift in the threshold voltage of an ISFET sensor. The experimental data show that the SnO 2 /SiO 2 gate ISFET sensors have a linear pH response of about 58 mV pH −1 in a concentration range between pH 2 and pH 10. In addition, the other characteristics of this sensor, such as temperature effect, drift effect, hysteresis and response time were also investigated in this paper.

Information processing in schizophrenia and bipolar disorder: a discriminant analysis.

Abstract: Schizophrenia and bipolar disorder are two distinct categories of mental disorders in the DSM-IV. However, it is often difficult to make a differential diagnosis because of the overlapping symptoms. A potential adjunct in the classification of schizophrenia and bipolar disorder is the application of information processing models, as patients with schizophrenia and possibly those with bipolar disorder have information processing deficits. A study was conducted in which a computerized battery of information processing tasks (called COGLAB) was administered to three participant groups: patients with schizophrenia, patients with bipolar disorder, and normal controls. The tasks included the Mueller-Lyer illusion, reaction time, size estimation, a variant of the Wisconsin Card Sorting Test, backward masking, and Asarnow continuous performance. Discriminant analyses were used to investigate the differences among the three groups. Results indicated that COGLAB correctly classified 75.5% of the cases of schizophrenia and bipolar disorder. The Mueller-Lyer illusion and the number of perseverative errors on the card sort most powerfully discriminated the two groups.

A Preliminary Study of Negative Poisson's Ratio of Laminated Fiber Reinforced Composites:

Abstract: Composite materials can be regarded as structures, so there is a great opportunity to design a wide range of properties for such kind of material to meet the various application requirements, even ...

New UV-curable cyclotriphosphazenes as fire-retardant coating materials for wood

Abstract: A series of (2-hydroxyethylmethacrylate)(n-propoxy)cyclotriphosphazenes (HPCP) has been prepared by the reaction of N3P3Cl6 with n-propanol and 2-hydroxyethylmethacrylate (HEMA) sequentially in the appropriate solvents. These phosphazene compounds are characterized by a combination of Fourier transform infrared, ultraviolet, and nuclear magnetic resonance spectroscopies. It was found that the compounds were soluble in most of the organic solvents, exhibited an absorption between 207–216 nm, and were curable by UV irradiation. After curing, the surfaces of the HPCP-coated woodblocks were transparent and had a fire-retardant property, which has been ascribed to the intumescent behavior during the burning process. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 115–122, 1998

Reducing lipid peroxidation stress of erythrocyte membrane by α-tocopherol nicotinate plays an important role in improving blood rheological properties in type 2 diabetic patients with retinopathy

Abstract: The effects of alpha-tocopherol nicotinate on blood viscoelasticity and viscosity and on lipid peroxidation stress in erythrocyte membranes in patients with Type 2 DM were investigated. Thirteen Type 2 diabetic subjects with retinopathy were given alpha-tocopherol nicotinate 300 mg tds, after meals, for 3 months. The treatment resulted in significant reductions of blood viscosity at different shear rates (e.g. -2.23 +/- 2.82 p<0.015, gamma = 1.5 s(-1)) and viscoelasticity (p<0.004); resistance of erythrocyte deformation (p<0.001) and lipid peroxidation stress in red cell membrane (malondialdehyde or MDA reduced by 0.17 +/- 0.13 nmol l(-1) p<0.005). Plasma viscosity, red cell rigidity, and HbA1c were unchanged. There were negative linear correlations between the indices of red cell deformability and the levels of MDA of red cell membrane both pre- and post-treatment (e.g. R = -0.79, p<0.001; R = -0.78, p<0.002, n = 13; pre- and post-, respectively). We suggest that the improvements of rheological properties of blood and red cell deformability by alpha-tocopherol nicotinate are mainly attributed to reducing lipid peroxidation stress on membrane of red blood cells. The treatment may be useful in slowing deterioration of microangiopathy in Type 2 DM.

Preparation and characterization of heparin-containing SBS-g-DMAEMA copolymer membrane

Abstract: The grafting of dimethyl amino ethyl methacrylate (DMAEMA) onto styrene-butadiene-styrene triblock copolymer (SBS) membrane was subsequently conducted by UV-radiation induced graft copolymerization without degassing to obtain the SBS-g-DMAEMA copolymer membrane. The substituted amino groups on the SBS-g-DMAEMA graft copolymer membrane were quaternized with iodomethane, and then the membrane was treated with heparin to prepare the heparin-containing SBS-g-DMAEMA copolymer membrane (SBS-g-DMAEMA-HEP). The graft copolymer membrane (SBS-g-DMAEMA) and the heparin-containing SBS-g-DMAEMA copolymer membrane (SBS-g-DMAEMA-HEP) were characterized by FTIR spectroscopy. The heparin content was determined by toluidine blue heparin assay. Contact angle, water content, and protein adsorption of fibrinogen and albumin experiments were also performed to evaluate the effect of graft amount and heparin content on the biocompatibility of SBS-g-DMAEMA and SBS-g-DMAEMA-HEP graft copolymer membranes. By using Kaelble's equation, the surface tension of SBS-g-DMAEMA and SBS-g-DMAEMA-HEP were determined. It was found that with increasing grafting amount and the heparin content, the surface tension and water content of SBS-g-DMAEMA membrane increased, whereas the contact angle decreased. The amount of the adsorption of albumin and fibrinogen decreased with increasing graft amount and heparin content. However, there was a minimum for adsorption of proteins in the SBS-g-DMAEMA and SBS-g-DMAEMA-HEP membranes.

Slider-crank mechanism control using adaptive computed torque technique

Abstract: The position control of the slider of a slider-crank mechanism, which is driven by a permanent magnet (PM) synchronous motor, using an adaptive computed torque technique, is studied. First, the mathematical model of the motor mechanism coupling system is described, where the Hamilton principle and the Lagrange multiplier method are applied to formulate the equation of motion. Secondly, assuming that the parameters of the system are well known, according to the computed torque technique, a robust controller is designed to control the slider-crank mechanism. Then, considering the existence of the uncertainties of the system, an adaptive computed torque controller is designed based on the Lyapunov stability. Moreover, to increase the execution rate of the control algorithms, a digital signal processor (DSP)-based control computer is devised to control the motor mechanism coupling system.

Sliding-mode motion/force control of constrained robots

Abstract: A sliding-mode controller is proposed for the simultaneous position and force control of constrained robot manipulators with parametric uncertainties. Based on this controller, the trajectories of the closed-loop system can reach a stable sliding surface in finite time. Under this condition, the asymptotic convergence of the motion error and force error can be successfully ensured with improved results compared to previous studies.

Induction motor servo drive with adaptive rotor time-constant estimation

Abstract: An indirect filed-oriented induction motor (IM) position servo drive with adaptive rotor time-constant estimation and an on-line trained neural network controller is presented. First, the rotor time-constant is estimated real-time on the basis of the model reference adaptive system (MRAS) theory. Next, a linear model-following controller (LMFC) is designed according to the estimated plant model to allow the state responses of the plant to follow the reference model. Then an augmented signal generated from the proposed neural network controller, whose connective weights are trained on-line according to the model-following error of the states, is added to the LMFC system to preserve a favorable model-following characteristic under various operating conditions.

Ultrasonic motor servo-drive with online trained neural-network model-following controller

Abstract: An ultrasonic motor (USM) servo-drive with an online trained neural-network model-following controller is proposed. First, the driving circuit for the USM, which is a two-phase chopper-inverter combination, is introduced. Since the dynamic characteristics of the USM are difficult to obtain and the motor parameters are time varying, an online trained neural-network model-following controller is proposed to control the rotor position of the USM. An accurate tracking response can be obtained by random initialisation of the weights and biases of the network owing to the powerful online learning capability. Moreover, the influences of parameter variations and external disturbances of the USM servo-drive can be effectively reduced by the neural-network controller.

Two new constituents from the leaves of magnolia coco

Abstract: A new amide, magnolamide (1), and a new lignan, magnolone (2), whose structures were determined on the basis of spectral analysis, were found in the leaves of Magnolia coco. Eleven known compounds (episesamin, sesamin, magnolol, fargesin, aschantin, epieudesmin, syringaresinol, syringaresinol-O-β-d-glucopyroside, scoparone, oxoanolobine, and dicentrinone) were also isolated.