Browsing by Author "Tsai, JL"

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A new adaptive notch filter with constrained poles and zeros using Steiglitz-McBride method
(1998)
Cheng, MH
;
Tsai, JL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper we present a new adaptive notch filter (ANF) using the well-known Steiglitz-McBride method (SMM) [1] for an IIR filter with the constrained poles and zeros. The proposed ANF, termed as SMM-ANF, converges to the unbiased solution, has fast convergence speed, and requires less computational complexity than existing recursive maximum likelihood adaptive notch filters (RML-ANF) [2]. In the stationary environments, we analyze SMM-ANF convergence properties using the ordinary differential equation (ODE) [4] technique; we derive conditions for the SMM-ANF convergence solution unbiased. Simulations further display that SMM-ANF has better resolution in identifying frequencies of multiple sine waves than RML-ANF. In the nonstationary environments, we also show that SMM-ANF and RML-ANF have approximately identical tracking performance. Simulations are also done to verify the theoretically derived results.
A new IIR adaptive notch filter
(2006-07-01)
Cheng, MH
;
Tsai, JL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A new IIR adaptive notch filter (ANF) with fast convergence rate, accurate estimation of notch frequencies, and modest realization complexity is presented in this paper. The problem of obtaining a notch filter from a given signal containing multiple sine waves in noise is first formulated as the conventional problem of system identification. Then the new ANF is developed via the algorithm of Steiglitz McBride. Extensive simulations have been performed to verify the effectiveness of the ANF. (C) 2005 Elsevier B.V. All rights reserved.
An intuitive and device-independent method of generating color atlases for electronic displays
(1998-01-01)
Tsai, JL
;
Perng, DB
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
We propose a HCL mix color system that can describe accurate colors on different electronic displays. Algorithms for computing the threshold values of chroma and lightness are devised so that the HCL mix color system can create the 3D color gamut of a display. We propose an intuitive and device-independent method of generating a color atlas in the HCL mix color system. Users can find the desired colors in the 3D color gamut by using perceptually descriptive items for hue names, color tones, and lightness levels. The system is helpful for color schemes of computer-designed products. Simulation results of generated color atlases are given to show the feasibility and effectiveness of the method.
An intuitive and device-independent method of generating color atlases for electronic displays
(1998-01-01)
Tsai, JL
;
Perng, DB
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
We propose a HCL mix color system that can describe accurate colors on different electronic displays. Algorithms for computing the threshold values of chroma and lightness are devised so that the HCL mix color system can create the 3D color gamut of a display. We propose an intuitive and device-independent method of generating a color atlas in the HCL mix color system. Users can find the desired colors in the 3D color gamut by using perceptually descriptive items for hue names, color tones, and lightness levels. The system is helpful for color schemes of computer-designed products. Simulation results of generated color atlases are given to show the feasibility and effectiveness of the method.
Fabrication and mechanical properties of glass fiber/epoxy nanocomposites
(2006)
Tsai, JL
;
Kuo, JC
;
Hsu, SM
;
機械工程學系
;
Department of Mechanical Engineering
This research is aimed to fabricate glass fiber/epoxy nanocomposites containing organoclay as well as to understand the organoclay effect on the in-plane shear strength of the nanocomposites. To demonstrate the organoclay effect, three different loadings of organoclay, were dispersed in the epoxy resin using mechanical mixer followed by sonication. The corresponding glass/epoxy nanocomposites were prepared by impregnating the organoclay epoxy mixture into the dry glass fiber through a vacuum hand lay-up process. Off-axis block glass/epoxy nanocomposites were tested in compression to produce in-plane shear failure. It is noted only the specimens showing in-plane shear failure mode were concerned in this study. Through coordinate transformation law, the uniaxial failure stresses were then converted to a plot of shear stress versus transverse normal stress from which the in-plane shear strength was obtained. Experimental results showed that the fiber/epoxy nanocomposite exhibit higher in-plane shear strength than the conventional composites. This increased property could be ascribed to the enhanced fiber/matrix adhesion promoted by the organoclay.
Investigating strain rate effect on transverse compressive strength of fiber composites
(2006)
Tsai, JL
;
Kuo, JC
;
機械工程學系
;
Department of Mechanical Engineering
This research aims to investigate strain rate effect on transverse compressive strength of unidirectional fiber composites. Both glass/epoxy and graphite/epoxy composites were taken into account in this study. To demonstrate strain rate effect, composite brick specimens were fabricated and tested to failure in the transverse direction at strain rate ranges from 10(-4)/S to 500/s. For strain rate less than 1/s, the experiments were conducted by a hydraulic MTS machine. However, the higher strain rate tests were performed using a Split Hopkinson Pressure Bar (SHPB). Experimental observations reveal that the transverse compressive strengths increase corresponding to the increment of the strain rates. A semi-logarithmic function was employed to describe the rate sensitivity of the transverse compressive strength. SEM photographic on the failure surfaces depicts that for glass/epoxy composites, the failure mechanism is mainly due to the matrix shear failure, however, for the graphite/epoxy composites, it becomes the fiber and epoxy interfacial debonding which could dramatically reduce the transverse compressive strengths of the fiber composites.
Strain rate effect on in-plane shear strength of unidirectional polymeric composites
(2005-10-01)
Tsai, JL
;
Sun, CT
;
機械工程學系
;
Department of Mechanical Engineering
The strain rate effect on the in-plane shear strength of unidirectional composites was investigated. Off-axis S2/8552 glass epoxy block specimens were employed to produce in-plane shear failure. In order to determine the strain rate effect, specimens were tested in compression at various strain rates. For strain rates less than 1/s, experiments were conducted on an MTS machine. For higher strain rates, they were performed using a Hopkinson pressure bar. Experimental observations indicated that, for composite specimens with off-axis angles less than 10 degrees, fiber microbuckling is the dominant failure mechanism. However, for the specimens with off-axis angles between 15 degrees and 45 degrees, in-plane sharing is the major failure mode. If the off-axis angle is greater than 45 degrees, out of plane shear failure would take place. Only the in-plane shear failure mechanism was concerned in this study. The shear strain rate was obtained from the uniaxial strain rate by relating the effective plastic strain rate to the plastic shear strain rate with the aid of a viscoplasticity model. Through coordinate transformation law, the uniaxial failure stresses were then converted to a plot of shear stress versus transverse normal stress from which the shear strength in the absence of transverse normal stress (sigma(22) = 0) was obtained. Experimental results showed that the shear strength of the composite is quite sensitive to strain rate and the shear strength increases as strain rate increases. In contrast, the shear failure strain decreases as strain rate increases. (c) 2005 Elsevier Ltd. All rights reserved.
Strain rate effect on mechanical behaviors of nylon 6-clay nanocomposites
(2006)
Tsai, JL
;
Huang, JC
;
機械工程學系
;
Department of Mechanical Engineering
This study aims to investigate strain rate effect on the mechanical behaviors of nylon 6-clay nanocomposites. Both dry and wet nylon 6-clay nanocomposites are examined in this study. To determine the strain rate effect, the nylon 6 nanocomposites with 5 wt% loading of the organoclay are tested in compression at different strain rates. For strain rates less than 1/s, the experiments are conducted using a hydraulic MTS machine. However, the high strain rate tests are performed using a split Hopkinson pressure bar (SHPB). To establish reliable dynamic stress and strain curves for the nanocomposites, a pulse-shaper technology is employed in the SHPB tests. Experimental observations reveal that for dry nanocomposites, the linear portions of the stress and strain curves are not affected substantially by the strain rates, but the yielding stresses increase with the increment of the strain rates. On the other hand, for the wet nanocomposites, the stress and strain curves are almost nonlinear demonstrating significant stiffening behaviors as the strain rates increase. This stiffening behavior is continuous until the stress and strain curves are almost linear at the strain rate of 500/s. Comparison of nylon 6-clay nanocomposites and unfilled nylon 6 indicates that the supplement of 5 wt% organoclay in the dry nylon 6 can enhance the Young's modulus to 32% within the tested strain rate ranges. Moreover, for the wet nylon reinforced with organoclay, the increment of Young's modulus can be achieved up to 43%.