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1

Approximation by Szász type operators including Sheffer polynomials

Rao N., Wafi A., Deepmala A.

Journal of Mathematics and Applications

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2017

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Vol. 40

135--148

EN

In present article, we discuss voronowskaya type theorem, weighted approximation in terms of weighted modulus of continuity for Szász type operators using Sheffer polynomials. Lastly, we investigate statistical approximation for these sequences.

2

Modelling the effects of preheating on angular distortions in one sided fillet welds

Sadat Ali M., Rao S., Rao N.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 2

578--583

EN

In all fusion welded joints, residual, transverse, lateral, angular and bowing deformations are observed. In fillet joints the angular distortion is the predominant deformation. The distortions and thermal history of a fillet joint can be measured experimentally which is not economically viable all times. It is time consuming and the deformation can be measured only after the completion of the joining process. So prevention is not possible. In the present work a numerical elasto-plastic thermo mechanical model has been developed for predicting the thermal history and resulting angular distortions of manual metal arc welding in one sided fillet joints. To create a realistic simulation of the single sided fillet welding, a moving distributed heat source is used in finite element model. The effect of filler metal deposition is simulated by implementing a birth and death process for the elements. The temperature dependent material properties are used for predicting the transient temperature distribution in the material which in turn helps to predict the angular distortion profiles of the fillet joint. The simulated modeling results obtained are found to be in complete agreement with the experimental values.

3

Mixture model and Markov random field-based remote sensing image unsupervised clustering method

Hou Y., Yang Y., Rao N., Lun X., Lan J.

Opto-Electronics Review

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2011

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Vol. 19, No. 1

83-88

EN

In this paper, a novel method for remote sensing image clustering based on mixture model and Markov random field (MRF) is proposed. A remote sensing image can be considered as Gaussian mixture model. The image clustering result corresponding to the image label field is a MRF. So, the image clustering procedure is transformed to a maximum a posterior (MAP) problem by Bayesian theorem. The intensity difference and the spatial distance between the two pixels in the same clique are introduced into the traditional MRF potential function. The iterative conditional model (ICM) is employed to find the solution of MAP. We use the max entropy criterion to choose the optimal clustering number. In the experiments, the method is compared with the traditional MRF clustering method using ICM and simulated annealing (SA). The results show that this method is better than the traditional MRF model both in noise filtering and miss-classification ratio.

4

An automatic hybrid method for retinal blood vessel extraction

Yang Y., Huang S., Rao N.

International Journal of Applied Mathematics and Computer Science

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2008

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Vol. 18, no 3

399-407

EN

The extraction of blood vessels from retinal images is an important and challenging task in medical analysis and diagnosis. This paper presents a novel hybrid automatic approach for the extraction of retinal image vessels. The method consists in the application of mathematical morphology and a fuzzy clustering algorithm followed by a purification procedure. In mathematical morphology, the retinal image is smoothed and strengthened so that the blood vessels are enhanced and the background information is suppressed. The fuzzy clustering algorithm is then employed to the previous enhanced image for segmentation. After the fuzzy segmentation, a purification procedure is used to reduce the weak edges and noise, and the final results of the blood vessels are consequently achieved. The performance of the proposed method is compared with some existing segmentation methods and hand-labeled segmentations. The approach has been tested on a series of retinal images, and experimental results show that our technique is promising and effective.