B. Ghosh

Bio: B. Ghosh is an academic researcher from University of Calcutta. The author has contributed to research in topics: Dispersion relation & Wave propagation. The author has an hindex of 1, co-authored 8 publications receiving 6 citations.

On Schlomilch's Integral Equation for the Ionospheric Plasma

Abstract: The analytical form of the absorption index appropriate to the D- and E-region of the ionospheric plasma is derived. It has been utilised to build up Schlomilch's integral equation. The corresponding solution is obtained in terms of certain ionospheric parameters. The variation of effective collision frequency with height has been computed numerically from the derived solution. The results are presented graphically along with an earlier work.

Field solution in an anisotropic plasma imbedded in a moving dielectric medium

Abstract: Wave equations in an anisotropic plasma imbedded in a moving dielectric medium have been derived through Maxwell-Minkowski relations. These are solved for longitudinal and transverse cases of propagation. The dispersion relation within the medium has been deduced through which the nature of splitting may be understood.

Čerenkov radiation within the Earth's upper atmosphere

Abstract: A brief review of Cerenkov radiation within the upper atmospheric plasma has been presented. Different attempts in this context are systematically discussed. The results of analysis about the nature and characteristics of VLF hisses in terms of incoherent Cerenkov radiation are given in a concise manner. The occurrence of resonance cone has also been reported.

Quality Control and Discrimination of Andrographis paniculata (Burm. f.) Nees based on High Performance Liquid Chromatography Fingerprinting Combined with Chemometric Approaches

Abstract: Andrographis paniculata (Burm. f.) Nees is a potential medicinal herb used to treat a wide range of diseases. Various geographical origins of this herb might lead to the diversity of the herbal quality. The research aims to establish the chemical fingerprint for quality control of Andrographis paniculata and to find out the chemical markers for discrimination from different origin through the chemometrics approach. A high performance liquid chromatography photo diode array method was developed for simultaneous quantii¬cation of i¬ve marker compounds and for establishing the chemical fingerprint of Andrographis paniculata from 28 different locations of Eastern India. Chemometrics techniques including hierarchical cluster analysis, principal component analysis and partial least squares discriminant analysis were used. The similarities between each fingerprint of the sample and the simulative mean chromatogram were greater than 0.90. The relative standard deviation of relative retention time and relative peak area of precision, stability and repeatability of 12 characteristic peaks in these samples were less than 1 % and 3 %, respectively. The andrographolide content in the Odisha region varied in the range of 2.68-5.47 %. The results of hierarchical cluster analysis, principal component analysis and partial least squares discriminant analysis showed that Andrographis paniculata could be successfully grouped into two groups in accordance with the origin. Andrographolide (visual infusion phlebitis score >1.5) was the key discriminatory marker for discriminating the samples. The high performance liquid chromatography fingerprint combined with chemometric approaches could be used as an effective tool for discriminating the herb from different origins and quality control of Andrographis paniculata.

Transient heating of the upper atmosphere by auroral electric field

Abstract: Magnetohydrodynamic formulation has been used to deduce the velocity distribution of the upper atmospheric movement caused by the auroral electric field at the thermospheric height. The expressions for Joule heating and viscous heating are obtained. Numerical analysis has been made to estimate their magnitudes as well as the rate of their variations with time. The results are presented graphically.

Solving the nonlinear Schlomilch’s integral equation arising in ionospheric problems

Abstract: In this paper, the linear and nonlinear Schlomilch’s integral equations and their generalized forms are studied. The Schlomilch’s integral equations are used for many ionospheric problems, atmospheric and terrestrial physics. The generalized fractional order of the Chebyshev orthogonal functions (GFCF) collocation method is used to handle many forms of Schlomilch’s integral equations. The GFCF method can be used in the applied physics, applied mathematics, and engineering applications. The reliability of the GFCF method is justified through illustrative examples.

RADIATION FROM A UNIFORMLY MOVING CHARGE IN AN ANISOTROPIC PLASMA. Technical Report No. 389

Abstract: The radiation from a point charge moving uniformly in a plasma is investigated when the charge is moving in the direction of an external magnetic field. In general, there are two modes, for each of which all the components of the electric and magnetic field are present. The two parameters of interest in this problem are the ratio of the velocity of the charges to the free-space velocity of electromagnetic waves, and the ratio of the gyromagnetic frequency to the plasma frequency of the electrons. For two sets of values of these parameters, the frequency and the angular spectrum of the emitted radiation are obtained. In certain cases, as many as three Cherenkov rays are found to propagate in the same direction; these multiple-rays, however, correspond to different frequency components and to different modes of propagation. The motivation for this investigation is indicated briefly. (auth)

Two efficient methods for solving Schlömilch’s integral equation

Abstract: In this paper, the exact solutions of the Schlomilch’s integral equation and its linear and non-linear generalized formulas with application are solved by using two efficient iterative methods. The Schlomilch’s integral equations have many applications in atmospheric, terrestrial physics and ionospheric problems. They describe the density profile of electrons from the ionospheric for awry occurrence of the quasi-transverse approximations. The paper aims to discuss these issues.,First, the authors apply a regularization method combined with the standard homotopy analysis method to find the exact solutions for all forms of the Schlomilch’s integral equation. Second, the authors implement the regularization method with the variational iteration method for the same purpose. The effectiveness of the regularization-Homotopy method and the regularization-variational method is shown by using them for several illustrative examples, which have been solved by other authors using the so-called regularization-Adomian method.,The implementation of the two methods demonstrates the usefulness in finding exact solutions.,The authors have applied the developed methodology to the solution of the Rayleigh equation, which is an important equation in fluid dynamics and has a variety of applications in different fields of science and engineering. These include the analysis of batch distillation in chemistry, scattering of electromagnetic waves in physics, isotopic data in contaminant hydrogeology and others.,In this paper, two reliable methods have been implemented to solve several examples, where those examples represent the main types of the Schlomilch’s integral models. Each method has been accompanied with the use of the regularization method. This process constructs an efficient dealing to get the exact solutions of the linear and non-linear Schlomilch’s integral equation which is easy to implement. In addition to that, the accompanied regularization method with each of the two used methods proved its efficiency in handling many problems especially ill-posed problems, such as the Fredholm integral equation of the first kind.

Application of a Multilayer Perceptron Artificial Neural Network for the Prediction and Optimization of the Andrographolide Content in Andrographis paniculata

Abstract: Andrographolide, the principal secondary metabolite of Andrographis paniculata, displays a wide spectrum of medicinal activities. The content of andrographolide varies significantly in the species collected from different geographical regions. Therefore, this study aims at investigating the role of different abiotic factors and selecting suitable sites for the cultivation of A. paniculata with high andrographolide content using a multilayer perceptron artificial neural network (MLP-ANN) approach. A total of 150 accessions of A. paniculata collected from different regions of Odisha and West Bengal in eastern India showed a variation in andrographolide content in the range of 0.28–5.45% on a dry weight basis. The MLP-ANN was trained using climatic factors and soil nutrients as the input layer and the andrographolide content as the output layer. The best topological ANN architecture, consisting of 14 input neurons, 12 hidden neurons, and 1 output neuron, could predict the andrographolide content with 90% accuracy. The developed ANN model showed good predictive performance with a correlation coefficient (R2) of 0.9716 and a root-mean-square error (RMSE) of 0.18. The global sensitivity analysis revealed nitrogen followed by phosphorus and potassium as the predominant input variables influencing the andrographolide content. The andrographolide content could be increased from 3.38% to 4.90% by optimizing these sensitive factors. The result showed that the ANN approach is reliable for the prediction of suitable sites for the optimum andrographolide yield in A. paniculata.