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Panchal J.M.,Government Engineering College | Joshi M.,Government Polytechnic for Girls | Gajjar P.N.,Gujarat University
Phase Transitions | Year: 2016

A first-principles plane wave self-consistent method with the Ultrasoftpseudopotential scheme in the framework of density functional theory is performed to study the high pressure structural, electronic and vibrational properties of InX (X = N, P) for the zinc-blende (ZnS/B3), rock-salt (NaCl/B1) and cesium-chloride (CsCl/B2) phases. We also calculate the phase transition pressures among these different phases. Conclusions based on electronic energy band structure, phonon dispersion and phonon density of states at high pressure phases along phase transition regions are outlined. © 2015 Taylor & Francis.

Upla K.P.,S V National Institute Of Technology | Joshi M.V.,Dhirubhai Ambani Institute of ICT | Gajjar P.P.,Government Polytechnic for Girls
IEEE Transactions on Geoscience and Remote Sensing | Year: 2015

In this paper, we propose a new approach for multiresolution fusion using contourlet transform (CT). The method is based on modeling the low spatial resolution (LR) and high spectral resolution multispectral (MS) image as the degraded and noisy version of their high spatial resolution version. Since this is an ill-posed problem, it requires regularization in order to obtain the final solution. In this paper, we first obtain the initial estimate of the fused image from the available MS image and the panchromatic (Pan) image by using the CT domain learning. Since CT provides better directional edges, the initial estimate has better edge details. Using the initial estimate, we obtain the degradation that accounts for the aliasing between the LR MS image and fused image. Regularization is carried out by modeling the texture of the final fused image as a homogeneous Markov random field (MRF) prior, where the MRF parameter is estimated using the initial estimate. The use of MRF prior on the final fused image takes care of the spatial dependencies among the pixels. A simple gradient-based optimization technique is used to obtain the final fused image. Although we use homogeneous MRF, the proposed approach preserves the edges in the final fused image by retaining the edges from the initial estimate and by carrying out the optimization on nonedge pixels only. Therefore, the advantage of the proposed method lies in preserving the discontinuities without using the discontinuity preserving prior, thus avoiding the use of computationally taxing optimization techniques for regularization purposes. In addition, the proposed method causes minimum spectral distortion since it learns the texture using contourlet coefficients and does not use actual Pan image pixel intensities. We demonstrate the effectiveness of our approach by conducting the experiments using subsampled and nonsubsampled CT on different data sets captured using Ikonos-2, Quickbird, and Worldview-2 satellites. © 1980-2012 IEEE.

Shah N.H.,Gujarat University | Patel D.G.,Government Polytechnic for Girls
OPSEARCH | Year: 2015

The seller offers its buyer a credit period to settle the account which attracts more buyers and boosts market demand. However, the offer of credit period leads to default risk for the supplier. In this study, the seller is the decision maker. The demand is considered to be increasing with time and is dependent of permissible trade credit. The default risk in incurring in sales revenue is incorporated in objective of profit maximization. The necessary and sufficient conditions to obtain the seller’s optimal decision about setting the permissible credit period and purchase quantity are discussed. A procedure to determine the optimal solution is outlined. Finally, the numerical example is given to illustrate the theoretical results and sensitivity analysis is carried out to deduce some managerial insights. © 2014, Operational Research Society of India.

Kumar M.,LDRP Institute Of Technology and Research | Josh M.,Government Polytechnic for Girls | Gajjar P.N.,Gujarat University | Jani A.R.,Sardar Patel University
Solid State Phenomena | Year: 2014

The knowledge of the physical properties of liquid Pb-Bi alloys and those of eutectic composition especially, is of high scientific and practical importance. In present paper temperature dependent electrical conductivity as well as thermoelectric power of liquid Pb-Bi eutectic (Pb- 55.9%Bi) is studied in the framework of Ziman formalism through an electron-ion potential. Partial structure factor is calculated from the Faber-Ziman approach. The dependency of conductivity is interpreted alongwith various screening functions. The results are compared with experimental findings and the effect of screening function on conductivity is discussed. This elucidates that the conductivity data of liquid Pb-Bi system are in qualitative agreement with the nearly-free electron picture © (2014) Trans Tech Publications, Switzerland.

Upla K.P.,Sardar Vallabhbhai National Institute of Technology, Surat | Joshi S.,Sardar Vallabhbhai National Institute of Technology, Surat | Joshi M.V.,Dhirubhai Ambani Institute of ICT | Gajjar P.P.,Government Polytechnic for Girls
Journal of Applied Remote Sensing | Year: 2015

We propose two approaches of multiresolution image fusion using multistage guided filter and difference of Gaussians (DoGs). In a multiresolution image fusion problem, the given multispectral (MS) and panchromatic (Pan) images have high spectral and high spatial resolutions, respectively. One can obtain the fused image using these two images by injecting the missing high frequency details from the Pan image into the MS image. The quality of the final fused image will then depend on the method used for high frequency details extraction and also on the technique for injecting these details into the MS image. Specifically, we have chosen the guided filter and DoGs for detail extraction since these are more versatile in applications involving feature extraction, denoising, and so on. The detail extraction process in the fusion approach using a guided filter exploits the relationship between the Pan and MS images by utilizing one of them as a guidance image while extracting details from the other. The final fused image is obtained by adding the extracted high frequency details to the corresponding MS image. This way, the spatial distortion of the MS image is reduced by consistently combining the details obtained using both MS and Pan images. In the fusion method using DoGs, the high frequency details are extracted in the first and second levels by subtracting the blurred images of the original Pan. The extracted details at both DoGs are added to the MS image to obtain the final fused image. Advantages and disadvantages of each method are discussed and the comparison of the results is shown between the two. The results are also compared with the traditional and the state-of-the-art methods using the images captured using different satellites such as Quickbird, Ikonos-2, and Worldview-2. The quantitative assessment is evaluated using the conventional measures as well as using a relatively new index, i.e., quality with no reference which does not require a reference image. The results and measures clearly show that there is promising improvement in the quality of the fused image using the proposed approaches. © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE).

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