Chao-Hsing Hsu

Adaptive Pattern Nulling Design of Linear Array Antenna by Phase-Only Perturbations Using Memetic Algorithms

In this paper, the pattern nulling of a linear array for interference cancellation is derived by phase-only perturbations using memetic algorithm. It is proposed to improve the search ability of genetic algorithms. Memetic algorithm is a kind of an improved type of the traditional genetic algorithm. By using local search procedure, it can avoid the shortcoming of the traditional genetic algorithm, whose termination criteria are set up by using the trial and error method. The memetic algorithm is applied to find the pattern nulling of the proposed adaptive antenna. This design for radiation pattern nulling of an adaptive antenna can suppress interference by placing nulls at the directions of the interfering sources, i.e., to increase the signal to interference ratio (SIR). This proposed method is that an innovative adaptive antenna optimization technique is also able to solve the multipath problem which exists in practical wireless communication systems. The example is provided to justify the proposed phase-only perturbations approach based on memetic algorithms. Computer simulation results are given to demonstrate the effectiveness of the proposed method

Optimizing Beam Pattern of Linear Adaptive Phase Array Antenna Based on Particle Swarm Optimization

In this paper, an innovative optimal radiation pattern of an adaptive linear array is derived by phase-only perturbations using a Particle Swarm Optimization (PSO) algorithm. An antenna array is often made as an adaptive antenna. An optimal radiation pattern design for an adaptive antenna system is not only to suppress interference by placing a null in the direction of the interfering source but also to derive the maximum power pattern in the direction of the desired signal. The Signal Interference Ratio (SIR) can be maximized. The PSO algorithm is a new methodology in this study area, which can handle adaptive radiation pattern of antenna array. In this paper, an optimal radiation pattern of linear array is derived by phase-only perturbations using a PSO algorithm. PSO algorithms will be stated and computed for this problem. Then, the optimal solution can be derived, and simulation results are also presented in this paper.

Optimizing interference cancellation of adaptive linear array by phase-only perturbations using genetic algorithms

An antenna array is often used as an adaptive antenna. In this paper, the pattern nulling of a linear array for interference cancellation is derived by phase-only perturbations using genetic algorithms. This design for radiation pattern nulling of an adaptive antenna can suppress multiple interferences by placing nulls at the directions of the interfering sources, i.e., to increase the Signal Interference Ratio (SIR). One example is provided to justify the proposed phase-only perturbations approach based on genetic algorithms. The simulation results show that optimizing interference cancellation of adaptive linear array has been achieved by phase-only perturbations using genetic algorithms.

Optimizing linear adaptive broadside array antenna by amplitude-position perturbations using memetic algorithms

This paper presents an innovative implementation method of the broadside antenna by using adaptive array antenna. Compared with the conventional ones, its performance can be improved because it is possible to null the interfering signals adjustably and at the same time maximize the main lobe towards the array normal. Thus the optimal radiation pattern can be obtained. The conventional broadside array only can make a main lobe toward the array normal, but it can not cancel the interferences. So, it is easy to be seen for the significance of this proposed method. In many applications, it is required to have the maximum radiation of an array directed toward the array normal. An optimal radiation pattern design for an adaptive broadside array antenna is not only to derive the maximum power radiation at the array normal direction but also to suppress interference by placing nulls at the directions of the interfering sources. The signal to interference ratio (SIR) can be maximized. Memetic algorithm is used for the search of the optimal weighting of array factor of the optimal radiation pattern by amplitude-position perturbations.

Applying Image Processing Technology to Region Area Estimation

This paper proposes a method to measure a region area of field by using aerial images. An unmanned aerial vehicle (UAV) and image processing technology is used to capture images of the land and measure its area. The main advantage of using UAV to capture images is the higher degree of freedom; it can accord user’s operation to capture from various angles and heights to obtain more diversified information. Even taking pictures of a dangerous area, the user can remote the UAV in a safer place, and get the information of the area or the UAV in real time. In the experiment, an UAV is used to get images of the playground grassland which region area is known, and capture a group of images with same area from 70 to 120 m height every ten meters. In image processing process, edge detection and morphology are used to find the range of the interest region, and then count the number of pixels of it. We can get the relation between the different height and per pixels of the real area. Experimental results show that the average deviations of estimating unknown area are less than 2%.

Apply Image Technology to River Level Estimation

In this paper, an image based approach of the water flow information measurement is proposed. Applying the image based measurement is safely and efficiently non-contact method. This paper proposes the multiple virtual water level probes (MVWLP) method which can apply in any river environment without ruler where has regular water line on the embankment. This approach mainly applies the color space adjustable technique to reduce noises and uses the adaptive edge detection to extract the water line. Then, it sets some virtual probes on the discovered water line comparing with the preset probes to measure the current water level. We convince that the proposed methods are accurate, robust and adaptable enough to overcome multiple conditions presented in the sites.

Stability Analysis of Grey Discrete Time Time-Delay Systems: A Sufficient Condition

Uncertainties in a control system may be the results modeling errors, measurement errors, parameter variations and a linearization approximation. Most physical dynamical systems and industrial process can be described as discrete time uncertain subsystems. Similarly, the unavoidable computation delay may cause a delay time, which can be considered as timedelay in the input part of the original systems. The stability of systems with parameter perturbations must be investigated. The problem of robust stability analysis of a nominally stable system subject to perturbations has attracted wide attention (Mori and Kokame, 1989). Stability analysis attempts to decide whether a system that is pushed slightly from a steadystate will return to that steady state. The robust stability of linear continuous time-delay system has been examined (Su and Hwang, 1992; Liu, 2001). The stability analysis of an interval system is very valuable for the robustness analysis of nominally stable system subject to model perturbations. Therefore, there has been considerable interest in the stability analysis of interval systems (Jiang, 1987; Chou and Chen, 1990; Chen, 1992). Time-delay is often encountered in various engineering systems, such as the turboject engine, microwave oscillator, nuclear reactor, rolling mill, chemical process, manual control, and long transmission lines in pneumatic and hydraulic systems. It is frequently a source of the generation of oscillation and a source of instability in many control systems. Hence, stability testing for time-delay has received considerable attention (Mori, et al., 1982; Su, et al., 1988; Hmamed, 1991). The time-delay system has been investigated (Mahmoud, et al., 2007; Hassan and Boukas, 2007). Grey system theory was initiated in the beginning of 1980s (Deng, 1982). Since then the research on theory development and applications is progressing. The state-of-the-art development of grey system theory and its application is addressed (Wevers, 2007). It aims to highlight and analysis the perspective both of grey system theory and of the grey system methods. Grey control problems for the discrete time are also discussed (Zhou and Deng, 1986; Liu and Shyr, 2005). A sufficient condition for the stability of grey discrete time systems with time-delay is proposed in this article. The proposed stability criteria are simple

Robust Stability Analysis of Discrete Time System via an Optimization Approach

This paper presented an optimization approach for the robust stability analysis of discrete time system using memetic algorithm. The problem framework that needed to be made to the memetic algorithm for successful application to robustness analysis is described. A sufficient condition can successfully test for instability in uncertain linear system with nonlinear polynomial structures via the proposed optimization approach. Such memetic algorithm solves the robust stability analysis of discrete time system and shortens the convergence time successfully. An example is given to demonstrate the approach.