Genetic Simulated Annealing-Based Kernel Vector Quantization Algorithm

Codebook design plays an important role in the performance of signal processing based on vector quantization (VQ) just as speech coding, data compression and pattern recognition. LBG is one of the most effective algorithms and is widely used in codebook generation. Some problems still exist while its performance is remarkable. The LBG algorithm is easy to fall into local optimum. Usually there is strong correlation between the best solution and the initial selection for codebook design. It means that the quantization performance of codebooks from the same training data may varies in a certain range. There is also a certain probability for the algorithm to generate empty voronoi cell. In order to solve these problems, a novel algorithm based on ant colony clustering algorithm and genetic algorithm is proposed in this paper. The new algorithm takes advantage of the excellent global optimal searching ability of genetic algorithm. At the same time, the ant colony clustering algorithm is combined into the process. The dynamic change of the searching direction is adopted during crossover stage. The simulation results of line spectrum frequency parameters in mixed linear excitation prediction (MELP) show that the proposed algorithm is more efficient in its quantization performance compared to that of the LBG and genetic algorithms. Meanwhile, it has good stability in quantization performance. Index Terms - Codebook design, Vector quantization, Genetic algorithm, Ant colony clustering algorithm.

The design of vector quantizers (VQs) that yield minimal distortion is one of the most challenging problems in source coding. The problem of VQ design is to find a codebook that gives the least overall distortion (or equivalently, the largest signal-to-noise ratio (SNR)) for a given set of input vectors. This problem is known to be difficult as there are no known closed-form solutions. The generalized Lloyd algorithm (GLA) uses a finite set of training sequences as the data source and employs an iterative refinement. Given an initial codebook, the algorithm computes the nearest focally optimum codebook only. Genetic algorithms (GAs) are emerging as widely accepted optimization and search methods. These search methods are rooted in the mechanisms of evolution and natural genetics. They have a high probability of locating the globally optimal solution in a multimodal search space. A genetic algorithmic (GA) approach to vector quantizer design that combines the GLA is presented. We refer to this hybrid as the genetic generalized Lloyd algorithm (GGLA). It works briefly as follows. Initially, a finite number of codebooks, called chromosomes, are selected. In contrast to the GLA which refines only one codebook at a time, those codebooks undergo iterative cycles of reproduction in parallel. During an iteration, each codebook is updated by GLA or GA operations (i.e., mutation, crossover, and chromosome replacement). Three versions of the GGLAs are investigated depending on how the GLA or GA is selected.

A new hierarchal structure of the self-organizing map (SOM) with dynamic growth is presented and applied to codebook design in vector quantization (VQ) and image compression. The tree-structured approach for codebook design is motivated for reducing the high computational efforts in the training and image coding phases in traditional VQ algorithms. The DHSOM has the ability to self determine the structure of the network through heuristically rules, and its final structure reflects the variability of the data (image blocks). It is shown that training that training and coding times obtained with DHSOM algorithm are faster than conventional SOM and LBG algorithms, while the qualitative results are given.

Novel vector quantiser design using reinforced learning as a pre-process

Transform image coding using scalar quantization, pyramid vector quantization (PVQ), and generalized Lloyd algorithm vector quantization (VQ) and subband image coding using scalar quantization and pyramid vector quantization are considered. In a simulation study at low bit rates (0.5 bit/pel) the transform VQ coder generally provided the largest peak-signal-to-noise ratio (PSNR), although the PVQ subband coder was superior for some images. At larger encoding rates (for which, because of complexity, the generalized Lloyd algorithm VQ was not considered) the scalar-quantizer subband coder generally yielded larger PSNR than did the scalar-quantizer transform coder. The PVQ transform and subband coders provided similar values of PSNR, but the subband coded image had less blockiness than the transform-coded image. >

Numerical analysis of circular straight mufflers equipped with three chambers at high-order-modes

A new optimization method: Electro-Search algorithm

This research introduces a new approach to restoring an image disrupted by salt and pepper (SPN) noise using a genetic algorithm (GA) at all densities, called Enhanced GA (EGA). The key contribution of the proposed algorithm is to merge the genetic algorithm with imaging approaches that are embedded into the population in order to achieve rapid convergence. The concept is to turn a group of entities into a variety of iterations using crossover and mutation operators. This method evolves a series of images rather than a series of filter parameters. Experimental simulation results on various images using a peak signal-to-noise ratio (PSNR), structural similarity index parameter (SSIM), demonstrate that the suggested algorithm outperforms other methods for eliminating SPN where the noise density is moderate and high. Keywords: Enhanced genetic algorithm, Genetic algorithm, Noise removal, Salt and pepper.

Supervised Neural Network (NN) learning is a process in which input patterns and known targets are presented to a NN while it learns to recognize (classify, map, fit, etc.) them as desired. The learning is mathematically defined as an optimisation problem, i.e., an error function representing the differences between the desired and actual output, is being minimized (Bishop, 1995; Haykin, 1999). Because the most popular supervised learning techniques are gradient based (Backpropagation BP), they suffer from the so-called Local Minima Problem (Bishop, 1995). This has motivated the employment of Global Optimisation (GO) methods for the supervised NN learning. Stochastic and heuristic GO approaches including Evolutionary Algorithms (EA) demonstrated promising performance over the last decades (Smagt, 1994; Sexton et al., 1998; Jordanov & Georgieva, 2007; etc.). EA appeared more powerful than BP and its modifications (Sexton et al., 1998; Alba & Chicone 2004), but hybrid methods that combine the advantages of one or more GO techniques and local searches were proven to be even better (Yao, 1999; Rocha et al., 2003; Alba & Chicano, 2004; Ludemir et al., 2006). Hybrid methods were promoted over local searches and simple population based techniques in Alba & Chicone (2004). The authors compared five methods: two BP implementations (gradient descent and Levenberg-Marquardt), Genetic Algorithms (GA), and two hybrid methods, combining GA with different local methods. The methods were used for NN learning applied to problems arising in medicine. Ludemir et al. (2006) optimized simultaneously NN weights and topology with a hybrid method combining Simulated Annealing (SA), Tabu Search (TS) and BP. A set of new solutions was generated on each iteration by TS rules, but the best solution was only accepted according to the probability distribution as in conventional SA. Meanwhile, the topology of the NN was also optimized and the best solution was kept. Finally, BP was used to train the best NN topology found in the previous stages. The new methodology compared favorably with SA and TS on four classification and one prediction problems. Plaginakos et al. (2001) performed several experiments to evaluate various training methods – six Differential Evolution (DE) implementations (with different mutation operators), BP, BPD (BP with deflection), SA, hybridization of BP and SA (BPSA), and GA. They reported O pe n A cc es s D at ab as e w w w .in te ch w eb .o rg

Grasp planning based on geometrical information of objects can be approached as an optimization problem where a hand configuration that indicates a stable grasp needs to be located in a large search space. In this paper, we study the applicability of genetic algorithm (GA) on grasp planning optimization of 3D objects. The details are given on the selection of operators and parameters. Different sampling methods in the implementation of crossover and mutation operators are tested. A quantitative analysis including the comparison with random planner and simulated annealing (SA) method is performed to evaluate the performance of the GA based planner. GraspIt! simulator [1] is used for implementing the proposed algorithm and as the test environment. Two different quality metrics are considered. The result shows that GA is a robust method in the field of grasp planning. And the GA planner outperforms the SA planner in both pre-grasp quality and stability of the final grasp.

Motion estimation (ME) is a process of correlating the frames by pointing the blocks in the candidate frame similar to those in the previous frame. Hexagonal Search (HS) reduces 10–15% search points over Diamond Search (DS) with negligible Peak Signal to Noise Ratio (PSNR) loss. Adapting an optimization will achieve a massive improvement on the search process. The proposed HS-GA method combines the HS with genetic algorithm (GA) to optimize ME. The HS-GA method reduces 72% on average search points pre block (ASPB) with PSNR loss of 2.5 dB and single generation. If the GA is executed with 10 generations the PSNR loss is reduced to 0.48 dB, but ASPB drastically increase to ∼316%. The proposed work aims at multi objective on selection of better chromosomes and on control of generations to avoid the unnecessary generations to improve the GA. This process is named HSIGA(HS with Intelligent GA). The proposed HSIGA adapts five intelligent techniques like Histogram to decide new generations, Region based chromosome selection, Mutation on inner search gene, second rank valley point stopping criteria and interlaced HS to improve search process with negligible PSNR loss with in affordable search.

As the size of the images being captured increases, there is a need for a robust algorithm for image compression which satiates the bandwidth limitation of the transmitted channels and preserves the image resolution without considerable loss in the image quality. Many conventional image compression algorithms use wavelet transform which can significantly reduce the number of bits needed to represent a pixel and the process of quantization and thresholding further increases the compression. In this paper the authors evolve two sets of wavelet filter coefficients using genetic algorithm (GA), one for the whole image portion except the edge areas and the other for the portions near the edges in the image (i.e., global and local filters). Images are initially separated into several groups based on their frequency content, edges, and textures and the wavelet filter coefficients are evolved separately for each group. As there is a possibility of the GA settling in local maximum, we introduce a new shuffling operator to prevent the GA from this effect. The GA used to evolve filter coefficients primarily focuses on maximizing the peak signal to noise ratio (PSNR). The evolved filter coefficients by the proposed method outperform the existing methods by a 0.31 dB improvement in the average PSNR and a 0.39 dB improvement in the maximum PSNR.

BackgroundMining epistatic loci which affects specific phenotypic traits is an important research issue in the field of biology. Bayesian network (BN) is a graphical model which can express the relationship between genetic loci and phenotype. Until now, it has been widely used into epistasis mining in many research work. However, this method has two disadvantages: low learning efficiency and easy to fall into local optimum. Genetic algorithm has the excellence of rapid global search and avoiding falling into local optimum. It is scalable and easy to integrate with other algorithms. This work proposes an epistasis mining approach based on genetic tabu algorithm and Bayesian network (Epi-GTBN). It uses genetic algorithm into the heuristic search strategy of Bayesian network. The individual structure can be evolved through the genetic operations of selection, crossover and mutation. It can help to find the optimal network structure, and then further to mine the epistasis loci effectively. In order to enhance the diversity of the population and obtain a more effective global optimal solution, we use the tabu search strategy into the operations of crossover and mutation in genetic algorithm. It can help to accelerate the convergence of the algorithm.ResultsWe compared Epi-GTBN with other recent algorithms using both simulated and real datasets. The experimental results demonstrate that our method has much better epistasis detection accuracy in the case of not affecting the efficiency for different datasets.ConclusionsThe presented methodology (Epi-GTBN) is an effective method for epistasis detection, and it can be seen as an interesting addition to the arsenal used in complex traits analyses.

Visually lossless compression for Bayer color filter array using optimized Vector Quantization

Problem statement: Spam is an irrelevant or inappropriate message sent on the internet to a large number of newsgroups or users. A spam word is a list of well-known words that often appear in spam mails. Bloom Filter (BF) is used for identification of spam word. Approach: BF is a simple but powerful data structure that can check membership to a static set. The trade-off to use BF is a certain configurable risk of false positives. The odds of a false positive can be made very low if the hash bitmap is sufficiently large. Bin Bloom Filter (BBF) has number of BFs which assign group of words into bins with different false positive rates based on weight of the spam words. Genetic Algorithm (GA) was employed to minimize the total membership invalidation cost of BBF. GA had premature convergence problem. Simulated Annealing (SA) was incorporated with GA to prevent the premature convergence effectively. Results: The experimental results of total membership invalidation cost are analyzed for various sizes of bins. The results showed that the combined GA-SA model outperforms SA and GA model. Conclusion: GA has premature convergence due to its genetic operators that are not able to generate offsprings which are superior to the parents. So more number of similar chromosomes presented on the population. When GA is incorporated with SA new genes were introduced which causes diversity in the population and prevents premature convergence. The combined GA-SA outperforms GA and SA.