752 publications from this institution
There are more than two dozen variants of particle swarm optimization (PSO) algorithms in the literature. Recently, a new variant, called accelerated PSO (APSO), shows some extra advantages in convergence for global search. In the present study, we will introduce chaos into the APSO in order to further enhance its global search ability. Firstly, detailed studies are carried out on benchmark problems with twelve different chaotic maps to find out the most efficient one. Then the chaotic APSO (CAPSO) will be compared with some other chaotic PSO algorithms presented in the literature. The performance of the CAPSO algorithm is also validated using three engineering problems. The results show that the CAPSO with an appropriate chaotic map can clearly outperform standard APSO, with very good performance in comparison with other algorithms and in application to a complex problem.
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Solitary waves occur in the system of wave propagation in a dispersive energy conserving medium. We show that soliton-like travelling waves arise naturally in the flow of viscoelastic media.
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The flower pollination algorithm (FPA) is a nature-inspired algorithm for optimization. This chapter introduces the basic ideas of FPA and its demo implementation. Multi-objective optimization is also discussed with applications.
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Web services commonly employ Content Distribution Networks (CDNs) for performance and security. As web traffic is becoming 100% HTTPS, more and more websites allow CDNs to terminate their HTTPS connections. This practice may expose a website's user sensitive information such as a user's login password to a third-party CDN. In this paper, we measure and quantify the extent of user password exposure to third-party CDNs. We find that among Alexa top 50K websites, at least 12,451 of them use CDNs and contain user login entrances. Among those websites, 33% of them expose users' passwords to the CDNs, and a popular CDN may observe passwords from more than 40% of its customers. This result suggests that if a CDN infrastructure has a vulnerability or an insider attack, many users' accounts will be at risk. If we assume the attacker is a passive eavesdropper, a website can avoid this vulnerability by encrypting users' passwords in HTTPS connections. Our measurement shows that less than 17% of the websites adopt this countermeasure.
No abstract is provided for this article.
This chapter introduces the fundamentals of numerical solution of partial differential equations (PDEs), starting with the upwind scheme for first-order PDEs, followed by von Neumann stability analysis. Numerical methods such as the central difference scheme are then explained for second-order PDEs such as wave equation, heat conduction equation, and Poisson's equation, together with stability analysis of these schemes. Finally, the basic idea of the spectral method is outlined.
No abstract is provided for this article.
In this paper, the concept of analytical continuation is utilized to generate the electric field over a wide frequency band. The problem of interest is TM scattering from a conducting cylinder. A method of moments formulation is utilized to generate information about the current and its derivatives at a specific frequency. This information is utilized to extrapolate the current at other frequencies. The numerical results presented are in good agreement with exact data.
Despite the increasing popularity of metaheuristics, many crucially important questions remain unanswered. There are two important issues: theoretical framework and the gap between theory and applications. At the moment, the practice of metaheuristics is like heuristic itself, to some extent, by trial and error. Mathematical analysis lags far behind, apart from a few, limited, studies on convergence analysis and stability, there is no theoretical framework for analyzing metaheuristic algorithms. I believe mathematical and statistical methods using Markov chains and dynamical systems can be very useful in the future work. There is no doubt that any theoretical progress will provide potentially huge insightful into meteheuristic algorithms.
Trigonometry is an essential part of engineering mathematics. For example, in robotics, trigonometry can be useful in calculating the positions of robotic arms, rotations as well as other quantities. In addition, trigonometrical functions are also intrinsically related to complex numbers. This chapter introduces the fundamentals of trigonometrical functions.
Metaheuristic optimization algorithms are usually based on swarm intelligence,and these algorithms are often referred to as smart algorithms.We review some of the widely used algorithms for optimization,including ant and bee algorithms,bat algorithm,cuckoo search, firefly algorithm and particle swarm optimization.We also discuss the challenging issues concerning parameter tuning and parameter control in metaheuristic algorithms.