1,055 research outputs found
Nature-inspired Cuckoo Search Algorithm for Side Lobe Suppression in a Symmetric Linear Antenna Array
In this paper, we proposed a newly modified cuckoo search (MCS) algorithm integrated with the Roulette wheel selection operator and the inertia weight controlling the search ability towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL) and/or nulls control. The basic cuckoo search (CS) algorithm is primarily based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Levy flight behavior of some birds and fruit flies. The CS metaheuristic approach is straightforward and capable of solving effectively general N-dimensional, linear and nonlinear optimization problems. The array geometry synthesis is first formulated as an optimization problem with the goal of SLL suppression and/or null prescribed placement in certain directions, and then solved by the newly MCS algorithm for the optimum element or isotropic radiator locations in the azimuth-plane or xy-plane. The study also focuses on the four internal parameters of MCS algorithm specifically on their implicit effects in the array synthesis. The optimal inter-element spacing solutions obtained by the MCS-optimizer are validated through comparisons with the standard CS-optimizer and the conventional array within the uniform and the Dolph-Chebyshev envelope patterns using MATLABTM. Finally, we also compared the fine-tuned MCS algorithm with two popular evolutionary algorithm (EA) techniques include particle swarm optimization (PSO) and genetic algorithms (GA)
An Improved particle swarm optimization based on lévy flight and simulated annealing for high dimensional optimization problem
Particle swarm optimization (PSO) is a simple metaheuristic method to implement with robust performance. PSO is regarded as one of the numerous researchers' most well-studied algorithms. However, two of its most fundamental problems remain unresolved. PSO converges onto the local optimum for high-dimensional optimization problems, and it has slow convergence speeds. This paper introduces a new variant of a particle swarm optimization algorithm utilizing Lévy flight-McCulloch, and fast simulated annealing (PSOLFS). The proposed algorithm uses two strategies to address high-dimensional problems: hybrid PSO to define the global search area and fast simulated annealing to refine the visited search region. In this paper, PSOLFS is designed based on a balance between exploration and exploitation. We evaluated the algorithm on 16 benchmark functions for 500 and 1,000 dimension experiments. On 500 dimensions, the algorithm obtains the optimal value on 14 out of 16 functions. On 1,000 dimensions, the algorithm obtains the optimal value on eight benchmark functions and is close to optimal on four others. We also compared PSOLFS with another five PSO variants regarding convergence accuracy and speed. The results demonstrated higher accuracy and faster convergence speed than other PSO variants. Moreover, the results of the Wilcoxon test show a significant difference between PSOLFS and the other PSO variants. Our experiments' findings show that the proposed method enhances the standard PSO by avoiding the local optimum and improving the convergence speed
Towards Swarm Diversity: Random Sampling in Variable Neighborhoods Procedure Using a Lévy Distribution
Abstract. Particle Swarm Optimization (PSO) is a nondirect search method for numerical optimization. The key advantages of this metaheuristic are principally associated to its simplicity, few parameters and high convergence rate. In the canonical PSO using a fully connected topology, a particle adjusts its position by using two attractors: the best record stored for the current agent, and the best point discovered for the entire swarm. It leads to a high convergence rate, but also progressively deteriorates the swarm diversity. As a result, the particle swarm frequently gets attracted by sub-optimal points. Once the particles have been attracted to a local optimum, they continue the search process within a small region of the solution space, thus reducing the algorithm exploration. To deal with this issue, this paper presents a variant of the Random Sampling in Variable Neighborhoods (RSVN) procedure using a Lévy distribution, which is able to notably improve the PSO search ability in multimodal problems. Keywords. Swarm diversity, local optima, premature convergence, RSVN procedure, Lévy distribution. Hacia la diversidad de la bandada: procedimiento RSVN usando una distribución de Lévy Resumen. Particle Swarm Optimization (PSO) es un método de búsqueda no directo para la optimización numérica. Las principales ventajas de esta metaheurística están relacionadas principalmente con su simplicidad, pocos parámetros y alta tasa de convergencia. En el PSO canónico usando una topología totalmente conectada, una partícula ajusta su posición usando dos atractores: el mejor registro almacenado por el individuo y el mejor punto descubierto por la bandada completa. Este esquema conduce a un alto factor de convergencia, pero también deteriora la diversidad de la población progresivamente. Como resultado la bandada de partículas frecuentemente es atraída por puntos subóptimos. Una vez que las partículas han sido atraídas hacia un óptimo local, ellas continúan el proceso de búsqueda dentro de una región muy pequeña del espacio de soluciones, reduciendo las capacidades de exploración del algoritmo. Para tratar esta situación este artículo presenta una variante del procedimiento Random Sampling in Variable Neighborhoods (RSVN) usando una distribución de Lévy. Este algoritmo es capaz de mejorar notablemente la capacidad de búsqueda de los algoritmos PSO en problemas multimodales de optimización. Palabras clave. Diversidad de la bandada, óptimos locales, convergencia prematura, procedimiento RSVN, distribución de Lévy
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