Statistical process monitoring using an empirical Bayes multivariate process control chart

In this paper, we describe the theory underlying an empirical Bayesian approach to monitoring two or more process characteristics simultaneously. If the data is continuous and multivariate in nature, often the multivariate normal distribution can be used to model the process. Then, using Bayesian theory, we develop techniques to implement empirical Bayes process monitoring of the multivariable process. Lastly, an example is given to illustrate the use of our techniques. Copyright © 2001 John Wiley & Sons, Ltd.     

Effects of fluorine-implanted treatment on Ba0.7Sr0.3TiO3 films

The effects of F-ion implantation on the leakage and dielectric properties of the Ba_0.7Sr_0.3TiO₃ (BST) films were investigated. The BST film implanted with 1×10¹⁵ cm^–2 shows the optimum leakage performance. The leakage current density can be decreased by one order of magnitude as compared to that of the non-implanted sample at an applied voltage of 2 V. On increasing the implanted dose from 5×10¹⁴ to 5×10¹⁵ cm^–2, the dielectric constant first increases and then decreases due to the deteriorated crystallinity. It is found that the suitable F-ion dose can reduce the –OH contaminants and improve the dielectric and leakage properties.     

Effect of montmorillonite on thermal and moisture absorption properties of polyimide of different chemical structures

The thermal properties and the moisture absorption of three types of polyimide/montmorillonite nanocomposite were investigated: 3,3′,4,4′‐biphenyltetracarboxylic dianhydride‐4,4′‐oxydianiline (BPDA‐ODA); pyromellitic dianhydride‐ODA (PMDA‐ODA); and 3,3′,4,′‐benzophenone tetracarboxylic dianhydride‐ODA (BTDA‐ODA). The inhibition effect on in‐plane coefficients of thermal expansion (CTE) and moisture absorption of these polyimide nanocomposites by layered silicates from montmorillonite was found to decrease with the crystallinity in the pristine polyimides. The largest reduction, 30% in in‐plane CTE occurred in the case of amorphous BTDA‐ODA containing 5 wt % montmorillonite as compared with that of pure BTDA‐ODA, while the reduction in in‐plane CTE was 20% for the case of semicrystalline BPDA‐ODA. The maximum reduction in moisture absorption, 43%, also took place for the case of 3/97 ODA‐Mont/BTDA‐ODA as compared with that of pure BTDA‐ODA, whereas the semicrystalline 1/99 PPD‐Mont/BPDA‐ODA showed a 30% reduction as compared with that of pure BPDA‐ODA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1742–1747, 2001     

Performance evaluation of random power capture on mobile communications

Power assignment schemes are man‐made methods to enhance the capture effect of radio communications. In a previous study, Wen and Yang investigated the combined capture effect of the fixed power assignment scheme, Rayleigh fading, and near–far effect on the performance of packet radios. The performance analysis was limited to an infinite population environment. This assumption is reasonable for a conventional packet radio system with a vast service area. However, for a cellular mobile system, a finite population model should be used. In this paper, we analyse the combined natural and man‐made capture effect on the performance of a cellular system with finite population in each cell. A random power assignment scheme is adopted to produce the man‐made capture. The system throughput and delay are carried out by a Markov model. Some numerical calculations are used to demonstrate the degree of performance improvement. Copyright © 2001 John Wiley & Sons, Ltd.     

Performance evaluation of LIBTA/hybrid time‐slot selection algorithm for cellular systems

This paper studies the performance of radio assignment algorithms for portable access in cellular systems. Several channel access procedures are proposed and simulated using block oriented network simulator (BONeS) simulation of a model 36‐port system. Simulation results exhibit that load‐sharing system with LIBTA algorithm is better than directed retry system with the same algorithm by around 0.9 erlangs while better than quasi‐fixed channel assignment (QFCA) system by around 2 erlangs if the grade of service (GOS) is constrained to less than 10 per cent. Plus, a hybrid time‐slot selection procedure is proposed to enhance the system performance. It is observed that systems with hybrid time‐slot selection perform better than those with LIBTA algorithm in GOS under heavy load. It is also observed that load sharing system with hybrid time‐slot selection algorithm is better than directed retry system with the same algorithm by around 0.7 erlangs and better than QFCA system by around 2 erlangs. Copyright © 2001 John Wiley & Sons, Ltd.     

Complete methodology for electrical modeling of RFIC packages

A complete methodology based on broadband S-parameter measurement is proposed to establish the electrical models for radio-frequency integrated circuit (RFIC) packages. The research is focused on calibration of the test-fixture parasitics to obtain the intrinsic S-parameters from which an equivalent coupled lumped model can be extracted for any pair of package leads under test. Then a step-by-step optimization scheme is employed to construct an equivalent circuit for the whole package. A real example on modeling a 16-lead Thin Shrink Small Outline Package (TSSOP) has been demonstrated. The established model can account for various package effects at radio frequencies     

The Economical PAPR Minization Scheme for Combinative Coding Technique Applied OFDM Communication System

In this paper, we propose a new combinative scheme to combine with parity check and block coding methods for the reduction of the peak to average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) system. In the proposed schemes, the simulation results shown that Peak-to-Average Power Ratio (PAPR) can be reduced by 3.502 dB. The results of this mapped can be shown that PAPR is reduced. The principle of the scheme is illustrated with the specific example of an eight-carriers signal and its computer simulation results. All simulation results have compare with ideal channel case and AWGN case separately; both of cases are shown the PAPR reduced indeed. Do Horng Guo received his B.S. Degree in Electronic Engineering from National Taiwan Marine Science University, Keelung, Taiwan, in 1983, and M.S. Degree in Computer Communication from Northrop University, Los Angeles, USA, in 1986. He is enrolled in Ph.D program in Graduate Institute of Communication Engineering of Tatung University from 2001. His current interest includes wireless communication system and digital signal processing. Chau-Yun Hsu received his B.S. degree M.S. and Ph.D in Electrical Engineering from Tatung Institute of Technology, Taipei, Taiwan, in 1981, 1983 and 1988, respectively. He was the lecturer in Department of Electrical Engineering of Tatung University from 1983 to 1985. From 1988 to 1997, he served as the Associate professor of Tatung University. Since 1998, he has been the Chair Professor of Graduate Institute of Communication Engineering of Tatung University. Now he is also the chair of department of Electrical Engineering of Tatung University. His current interest includes Wireless Channel Model and Estimation, Machine Learning, Digital Signal Processing and Image Processing.     

An adaptive watermarking scheme for e-government document images

This paper proposes an adaptive watermarking scheme for e-government document images. The adaptive scheme combines the discrete cosine transform (DCT) and the singular value decomposition (SVD) using luminance masking. As a core of masking model in the human visual system (HVS), luminance masking is implemented to improve noise sensitivity. Genetic algorithm (GA), subsequently, is employed for the optimization of the scaling factor of the masking. Involving a number of steps, the scheme proposed through this study begins by calculating the mask of the host image using luminance masking. It is then continued by transforming the mask on each area into all frequencies domain. The watermark image, following this, is embedded by modifying the singular values of DCT-transformed host image with singular values of mask coefficient of host image and the control parameter of DCT-transformed watermark image using Genetic Algorithm (GA). The use of both the singular values and the control parameter respectively, in this case, is not only to improve the sensitivity of the watermark performance but also to avoid the false positive problem. The watermark image, afterwards, is extracted from the distorted images. The experiment results show the improved adaptive performance of the proposed scheme is in resistant to several types of attacks in comparison with the previous schemes; the adaptive performance refers to the adaptive parameter of the luminance masking functioned to improve the performance or robustness of an image from any attacks.     

Optimal Speed-Up Parallel Image Template Matching Algorithms on Processor Arrays with a Reconfigurable Bus System,

The image template matching problem is one of the fundamental problems of and has many practical applications in image processing, pattern recognition, and computer vision. It is a useful operation for filtering, edge detection, image registration, and object detection [13]. In this paper, we first design twoO[(M²/p²)log logM] andO[(M²/p²)+(M/p)log logp] time parallel image template matching algorithms on a 3-D processor array with a reconfigurable bus system usingp²N²processors with each processor containingO(1) andO(M/p) restricted memory for 1 ≤p≤M≤N, respectively, for anN×Ndigital image and anM×Mtemplate. By increasing the number of processors, these two proposed algorithms can be run inO(M²/p²) time for speeding up the time complexity usingp²M^1/cN²andp^2+1/cN²processors, respectively, wherecis a constant andc≥1. Furthermore, anO(1) time can be also obtained from these two proposed algorithms by usingM²+1^/cN²processors. These results improve the best known bounds and achieve both optimal and optimal speed-up in their time and processor complexities.     

MTPSO algorithm for solving planar graph coloring problem

In this paper, we proposed a modified turbulent particle swarm optimization (named MTPSO) model for solving planar graph coloring problem based on particle swarm optimization. The proposed model is consisting of the walking one strategy, assessment strategy and turbulent strategy. The proposed MTPSO model can solve the planar graph coloring problem using four-colors more efficiently and accurately. Compared to the results shown in Cui et al. (2008), not only the experimental results of the proposed model can get smaller average iterations but can get higher correction coloring rate when the number of nodes is greater than 30.