Ting T.-H.,Chinese Military Academy |
Wu K.-H.,Chung Cheng Institute of Technology
Journal of Magnetism and Magnetic Materials | Year: 2010
Polyaniline/BaFe12O19 (PANI/Ba ferrite) composites were synthesized by in situ polymerization at different aniline/Ba ferrite weight ratios (Ani/Ba ferrite=1/2, 1/1 and 2/1) and introduced into epoxy resin to be microwave absorber. The spectroscopic characterizations of the formation processes of PANI/Ba ferrite composites were studied using Fourier transform infrared, ultraviolet-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron spin resonance. Microwave-absorbing properties were investigated by measuring complex permittivity, complex permeability and reflection loss in the 2-18 and 18-40 GHz microwave frequency range using the free space method. The results showed that a wider absorption frequency range could be obtained by adding different polyaniline contents in Ba ferrite. © 2010 Elsevier B.V. All rights reserved.
Lin T.-W.,Chung Cheng Institute of Technology |
Wang C.-H.,Chung Cheng Institute of Technology
Journal of Intelligent Manufacturing | Year: 2012
This study presents a hybrid genetic algorithm (GA) to optimize the periodic preventive maintenance model in a series-parallel system. The intrinsic properties of a repairable system, including the structure of reliability block diagrams, maintenance priority of components, and their maintenance periods, are considered in developing the proposed hybrid GA. The importance measure of components is employed to account for these properties, identify important components, and determine their maintenance priorities. The optimal maintenance periods of these important components are then determined to minimize total maintenance cost given the allowable worst reliability of a repairable system using the GA search mechanism. An elitist conservation strategy is applied to retain superior chromosomes in the iterative breeding process to accelerate the approach toward the global optimum. Furthermore, the response surface methodology is utilized to systematically determine crossover probability and mutation probability in the GA instead of using the conventional trial-and-error process. A case study demonstrates the effectiveness and practicality of the proposed hybrid GA in optimizing the periodic preventive maintenance model in a series-parallel system. © 2010 Springer Science+Business Media, LLC.
Wang C.-C.,Chung Cheng Institute of Technology
Expert Systems with Applications | Year: 2011
This study compares the application of two forecasting methods on the amount of Taiwan export, the ARIMA time series method and the fuzzy time series method. Models discussed for the fuzzy time series method include the Factor models, the Heuristic models, and the Markov model. When the sample period is prolong in our models, the ARIMA model shows smaller than predicted error and closer predicted trajectory to the realistic trend than those of the fuzzy model, resulted in more accurate forecasts of the export amount in the ARIMA model. Especially, the coefficient of the error term for the previous period has increased to 79%, implying the influential effect of external factors. These external factors attribute to the export amount of Taiwan according to the economic viewpoints. However, this impact reduces as time progressing and the export amount of the lag period of 12 or 13 do not affect current export amount anymore. In conclusion, when the sample period is shorter with only a small set of data available, the fuzzy time series models can be utilized to predict export values accurately, outperforming the ARIMA model. © 2011 Published by Elsevier Ltd.
Tan K.-H.,Chung Cheng Institute of Technology
IEEE Transactions on Power Electronics | Year: 2016
A wavelet Petri fuzzy neural network (WPFNN) controller is proposed to control squirrel-cage induction generator (SCIG) system with an ac/dc power converter and a dc/ac power inverter for grid-connected wind power applications. First, the ac/dc power converter and the dc/ac power inverter are developed to deliver the electric power generated by a three-phase SCIG to power grid. Moreover, the ac/dc power converter and the dc/ac power inverter are mainly designed to control the mechanical rotor speed, dc-link voltage, and reactive power output of the SCIG system, respectively. Furthermore, since the varying active power outputs of the dc/ac power inverter seriously affect the tracking control of the dc-link voltage, a novel intelligent WPFNN controller is proposed to replace the traditional proportional-integral controller for the tracking control of the dc-link voltage in this study. In addition, the network structure and the online learning algorithm of the proposed WPFNN are described in detail. Finally, some experimental results are provided to show the effectiveness of the intelligent controlled-SCIG system using the proposed WPFNN controller for grid-connected wind power applications. © 1986-2012 IEEE.
Hou K.-H.,Chung Cheng Institute of Technology |
Chen Y.-C.,Chung Cheng Institute of Technology
Applied Surface Science | Year: 2011
The aim of this work is to obtain the electroplating parameters for preparation of Ni-W/Al2O3 composite coating with high tungsten content, high micro-hardness and excellent wear resistance by pulse plating procedure. Our results showed that the duty cycle is a dominant parameter for the tungsten content in the coating and the tungsten content increases significantly with increasing duty cycle. The further analysis showed the great influence of tungsten content on micro-hardness of the coating. A maximum micro-hardness of about 859 Hv was obtained in pulse electrodeposited Ni-W/Al2O3 composite with tungsten content of 40 wt.% at a peak current density of 20 A/dm2, a duty cycle of 80%, a pulse frequency of 1000 Hz and a particle loading of 10 g/L alumina in the plating bath. Although the hardness of Ni-W/Al2O3 composite coating was only slightly affected by the alumina content of the deposits prepared in present investigation, the alumina content effect on the tribological characteristic of Ni-W/Al2O3 composite coatings is significant. The friction coefficient was lowered to 0.25 and the wear loss was reduced to 1.05 mg by setting the control factors according to the values mentioned above for obtaining the coating with the highest micro-hardness. © 2011 Elsevier B.V.
Sze J.-Y.,Chung Cheng Institute of Technology |
Wu Y.-F.,Chung Cheng Institute of Technology
Progress in Electromagnetics Research | Year: 2010
A planar hexa-band internal antenna designed for mobile phone applications is presented. The antenna occupying a small area of 45 × 12mm2 is placed on the top no-ground portion of the system circuit board with a ground-plane size of 45 × 100mm2. The design begins with constructing a meandered monopole. With a parasitic and an impedance-adjustment structure subsequently added, the resulting antenna can be viewed as a printed planar inverted-F antenna with a parasitic resonant element. Two wide impedance bands can be generated by the designed antenna to support GSM 850, GSM 900, DCS, PCS, UMTS, and 2.4-GHz WLAN operations. The measurement was found to agree reasonably well with the simulation. Design procedures and rules along with the design concepts behind are all presented in detail.
Cheng S.-J.,Taiwan Power |
Miao J.-M.,National Pingtung University of Science and Technology |
Wu S.-J.,Chung Cheng Institute of Technology
Applied Energy | Year: 2013
The main purpose of this paper is to realize a metamodeling optimal approach that can be employed cost-efficiently and systematically to improve the performance of power density in PEMFC. First, an power density database is generated that corresponds to different levels of PEMFC unit operating parameters (factors) using the Design of Experiment (DoE) scheme, screening experiments, and Taguchi Orthogonal Array (OA). Then, metamodel is constructed by Radial Basis Function Neural Network (RBFNN) to represent the PEMFC system as a nonlinear complex model. The cross-validation procedure is implemented to prove the metamodel correctness and generalization. Moreover, Genetic Algorithm (GA) is applied to avoid local point and reduce time consumption to search the global optimum in promoting the performance of design factors. The proposed optimization methodology from experimental results provides an effective and economical approach to improve the performance of fuel cell unit and can be easy extended to the fuel cell stack system in energy applications. © 2013.
Lou D.-C.,Chang Gung University |
Hu C.-H.,Chung Cheng Institute of Technology
Information Sciences | Year: 2012
Statistical steganalysis schemes detect the existence of secret information embedded by steganography. The x 2-detection and Regular-Singular (RS)-attack methods are two well-known statistical steganalysis schemes used against LSB (least significant bit) steganography. The embedded message length can be estimated accurately by these two steganalysis schemes. For secret communication, the resistance of steganography against steganalysis is very important for information security. To avoid the enemy's attempts, the statistical features between stego-images and cover images should be as similar as possible for better resistance to steganalysis. In this manuscript, a reversible histogram transformation function-based LSB steganographic method is proposed to resist statistical steganalysis. The experimental results show that the proposed method resists not only RS-attack but also x 2-detection methods. © 2011 Elsevier Inc. All rights reserved.
Deng S.,Chung Cheng Institute of Technology |
Yeh T.-H.,Chung Cheng Institute of Technology
International Journal of Production Economics | Year: 2011
Accurate cost estimation plays a significant role in industrial product development and production. This research applied least squares support vector machines (LS-SVM) method solving the problem of estimating the manufacturing cost for airframe structural projects. This research evaluated the estimation performance using back-propagation neural networks and statistical regression analysis. In case studies, this research considered structural weight and manufacturing complexity as the main factors in determining the manufacturing labor hour. The test results verified that the LS-SVM model can provide accurate estimation performance and outperform other methods. This research provides a feasible solution for airframe manufacture industry. © 2010 Elsevier B.V. All rights reserved.
Lin Y.-C.,Chung Cheng Institute of Technology
Remote Sensing | Year: 2015
Full-waveform airborne laser scanning systems provide fundamental observations for each echo, such as the echo width and amplitude. Geometric and physical information about illuminated surfaces are simultaneously provided by a single scanner. However, there are concerns about whether the physical meaning of observations is consistent among different scanning missions. Prior to the application of waveform features for multi-temporal data classification, such features must be normalized. This study investigates the transferability of normalized waveform features to different surveys. The backscatter coefficient is considered to be a normalized physical feature. A normalization process for the echo width, which is a geometric feature, is proposed. The process is based on the coefficient of variation of the echo widths in a defined neighborhood, for which the Fuzzy Small membership function is applied. The normalized features over various land cover types and flight missions are investigated. The effects of different feature combinations on the classification accuracy are analyzed. The overall accuracy of the combination of normalized features and height-based attributes achieves promising results ( > 93% overall accuracy for ground, roof, low vegetation, and tree canopy) when different flight missions and classifiers are used. Nevertheless, the combination of all possible features, including raw features, normalized features, and height-based features, performs less well and yields inconsistent results. © 2015 by the authors.