International Journal of Computational Intelligence and Applications

In this paper, we propose a Collaborative Clustering method based on Variational Bayesian Generative Topographic Mapping (VBGTM). To do so, we first propose a method that combines VBGTM and Fuzzy c-means (FCM). Collaborative clustering is useful to achieve interaction between different sources of information for the purpose of revealing underlying structures and regularities within data sets. It can be treated as a process of consensus building where we attempt to reveal a structure that is common across all sets of data. VBGTM was introduced as a variational approximation of Generative Topographic Mapping (GTM) to control data overfitting. It provides an analytical approximation to the posterior probability of the latent variables and the distribution of the input data in the latent space. It can be effectively applied to visualize and explore properties of the data. But when the number of latent points is large, similar units need to be grouped (i.e., clustered) to facilitate quantitative analysis of the map and the data. We use FCM to determine the prototypes as well as the resultant clusters and the corresponding membership functions of the input data, based on the latent variables obtained from VBGTM. So, by combining the two algorithms, we develop a method that can do visualization and clustering at the same time. We observe that the hybrid method (F-VBGTM) performs very well in terms of many cluster-validity indexes.

Metaheuristics are nondeterministic optimization algorithms used to solve complex problems for which classic approaches are unsuitable. Despite their effectiveness, metaheuristics require considerable computational power and cannot easily be used in time critical applications. Fortunately, those algorithms are intrinsically parallel and have been implemented on shared memory systems and more recently on graphics processing units (GPUs). In this paper, we present highly efficient parallel implementations of the particle swarm optimization (PSO), the genetic algorithm (GA) and the simulated annealing (SA) algorithm on GPU using CUDA. Our approach exploits the parallelism at the solution level, follows an island model and allows for speedup up to 346× for different benchmark functions. Most importantly, we also present a strategy that uses the generalized island model to integrate multiple metaheuristics into a parallel hybrid solution adapted to the GPU. Our proposed solution uses OpenMP to heavily exploit the concurrent kernel execution feature of recent NVIDIA GPUs, allowing for the parallel execution of the different metaheuristics in an asynchronous manner. Asynchronous hybrid metaheuristics has been developed for multicore CPU, but never for GPU. The speedup offered by the GPU is far superior and key to the optimization of solutions to complex engineering problems.

Traveling salesman problem (TSP) is one of well-known discrete optimization problems. The genetic algorithm is improved with the mixed heuristics to resolve TSP. The first heuristics is the four vertices and three lines inequality, which is applied to the 4-vertex paths to generate the shorter Hamiltonian cycles (HC). The second local heuristics is executed to reverse the i-vertex paths with more than two vertices, which also generates the shorter HCs. It is necessary that the two heuristics coordinate with each other in the optimization process. The time complexity of the first and second heuristics are O(n) and O(n³), respectively. The two heuristics are merged into the original genetic algorithm. The computation results show that the improved genetic algorithm with the mixed heuristics can find better solutions than the original GA does under the same conditions.

This paper deals with intelligent tuning by hybrid system composed of genetic algorithm and clonal selection (CS). This paper uses gain margin (GM) and phase margin (PM) to define the tuning margin of control system for optimal tuning. Up to this time, many intelligent algorithms have been tried in order to improve the intelligent controller performance for industrial areas such as power plant, motor control, chemical control, and so on. However, in the actual plant, they are many limitations in tuning approaching because of computing speed. Therefore, it is difficult to apply for getting optimum value in tuning. In this paper, novel computing scheme has been done by hybrid CS algorithm and genetic algorithm, GM, and PM to obtain an advanced value and effective approach for optimal parameters.

We propose in this paper a system to recognize handwritten digit strings, which constitutes a difficult task because of overlapping and/or joining of adjacent digits. To resolve this problem, we use a segmentation-verification of handwritten connected digits based conjointly on the oriented sliding window and support vector machine (SVM) classifiers. The proposed approach allows separating adjacent digits according the connection configuration by finding at the same time the interconnection points between adjacent digits and the cutting path. SVM-based segmentation-verification using the global decision module allows the rejection or acceptance of the processed image. Experimental results conducted on a large synthetic database of handwritten digits show the effective use of the oriented sliding window for segmentation-verification.

Segmentation of an image is the partition or separation of the image into disjoint regions of related features. In clinical practice, magnetic resonance imaging (MRI) is used to differentiate pathologic tissues from normal tissues, especially for brain tumors. The main objective of this paper is to develop a system that can follow a medical technician way of work, considering his experience and knowledge. In this paper, a step by step methodology for the automatic MRI brain tumor segmentation and classification is presented. Initially acquired MRI brain images are preprocessed by the Gaussian filter. After preprocessing, initial segmentation is done by hierarchical topology preserving map (HTPM). From the resultant images, the features are extracted using gray level co-occurrence matrix (GLCM) method, and the same are given as inputs to adaptive neuro fuzzy inference systems (ANFIS) for final segmentation and the classification of brain images into normal or abnormal. In case of abnormal, the MRI brain images are classified as benign subject (tumor without cancerous tissues) or malignant subject (tumor with cancerous tissues). Based on the analysis, it has been discovered that the overall accuracy of classification of our method is above 94%, and F₁-score is about 1. The simulation results also show that the proposed approach is a valuable diagnosing technique for the physicians and radiologists to detect the brain tumors.