Wyniki wyszukiwania - BazTech

1

Best approximation in quotient probabilistic normed space

Sen M., Nath S., Tripathy B. C.

Journal of Applied Analysis

|

2017

|

Vol. 23, nr 1

53--57

EN

In this article, we study the best approximation in quotient probabilistic normed space. We define the notion of quotient space of a probabilistic normed space, then prove some theorems of approximation in quotient space are extended to quotient probabilistic normed space.

2

Splat formation and degradation of hydroxyapatite during plasma spraying process

Mittal M., Nath S., Prakash S.

Advances in Materials Science

|

2011

|

Vol. 11, nr 2(28)

26-36

EN

Plasma spraying is most used thermal spray process for coating of bioceramic and bioinert materials. It is line of sight technique, easy to use and inexpensive as compared to other processes used for coatings. The main disadvantage of this technique for coating hydroxyapatite (HA) is that due to high temperature of plasma (of the order of 16000°C) HA tends to degrade into amorphous calcium phosphates. These amorphous phases are not desirable and have a tendency to dissolve in body environment. In this article an attempt has been made to understand the plasma spraying process for coating of hydroxyapatite.

3

A least area approach of Hough Transform for pattern recognition in seismic reflection

Nath S., Behura J.

Acta Geophysica Polonica

|

2003

|

Vol. 51, nr 2

155-164

EN

The intensive computational complexity, storage requirement, recognition of envelopes with parametric equations have rendered the standard Hough Transform interior to the intellectual mechanism of human's visual recognition. In this paper, a Modified Generalized Hough Transform is proposed which implements parametric equation of a straight line to establish relationship among various samples lying on a seismic reflector. It performs thresholding demarcation of interfaces in each window, establishment of continuity of interfaces from one window to another and mid-point smoothing. Based on its application on a zero-offset synthetic seismogram and a migrated CDP section presented here, the algorithm is found to be sensitive to the choice of window length. A time window of six samples or less with an equal degree of scrolling seems to the best suited for pattern recognition using this technique. However, a trade-off is necessary between the window length and the amount of overlap to obtain better reflection continuity.

4

Estimation of model parameters from one-dimensional vertical electrical sounding data using evolutionary programming technique

Shahid S., Nath S., Sircar A., Patra H.

Acta Geophysica Polonica

|

1999

|

Vol. 47, nr 3

335-348

EN

Calculus based algebraic algorithms like Singular Value Decomposition, Ridge Regression, Weighted Ridge Regression, etc. were used in the inversion of resistivity data till late 80's. With the advent of high speed computers having higher disk space and parallel processing environment, several global optimization techniques (simulated evolution, simulated annealing, very fast simulated annealing, etc.) are adapted to solve various inherent problems in the inversion of geophysical data. In the present paper an attempt is made to use Evolutionary Programming (EP) technique for the estimation of layer parameters from one-dimensional Vertical Electrical Sounding (VES) data. The algorithm is coded in FORTRAN 77 and tested on both synthetic and actual field data. The results, compared with those obtained by Singular Value Decomposition and borehole lithology, prove the efficiency and robustness of the EP approach.

5

Seismic transmission tomography a configurative approach

Chakraborty S., Nath S., Sengupta S.

Acta Geophysica Polonica

|

1998

|

Vol. 46, nr 4

389-408

EN

Seismic Transmission Tomography provides a method for direct estimation of velocity distribution in the subsurface from the P- or S-wave first arrival traveltime data. Both the data acquisition configuration and the reconstruction algorithm are equally important in imaging the subsurface lithostratigraphic unit. Out of the three transmission tomographic configurationssurface-to borehole, borehole-to-surface and cross-hole, the latter is ussually used in the transmission tomographic fiels investigation. The present study has two aims: (i) to test the performance of the SimultaneousInterative Reconstruction Technique (SIRT) algorithm coded here, and (ii) to show the necessity of a combined interpretation of the three source-reciver configurations. Using the standard formulations, initial parametrization is possible but not exact solution in terms of the velocity distribution in the subsurface and the location of an anomalous body in the halfspace. The SIRT scheme is found to yield satisfactory estimates of the subsurface from the data acquired by the three configurations. Both the synthetic and actual shear wave seismic tomographic data for the detection of galleries at North Searsole Colliery, Raniganj Coalfields, West Bengal, India, are used for an extensive analysis. The resoults presented in the form of raster images undoubtedly show the effectiviteness of SIRT scheme and also the good resolution acheved by a combined interpretation of the surface-ti-borehole, borehole-to-surface and cross hole omographic data.