arXiv subjects

Abhik Mukherjee

Publications and source records attributed to Abhik Mukherjee.

At least 19 recordsLinked to original sources

arXiv2023

Bending of pinned dust ion acoustic solitary waves in presence of charged space debris

We consider a low temperature plasma environment in the Low Earth Orbital (LEO) region in presence of charged space debris particles. The dynamics of (2+1) dimensional nonlinear dust ion acoustic waves with weak transverse perturbation, generated in the system is found to be governed by a forced Kadomtsev-Petviashvili (KP) equation, where the forcing term depends on charged space debris function. The bending phenomena of some exact dust ion acoustic solitary wave solutions in x-t and x-y planes are shown; that are resulted from consideration of different types of possible localized debris functions. A family of exact pinned accelerated solitary wave solutions has been obtained where the velocity changes over time but the amplitude remains constant. The shape of debris function also changes during its propagation. Also, a special exact solitary wave solution has been derived for the dust ion acoustic wave; that gets curved in spatial dimensions with the curvature depending upon nature of forcing debris function. Such intricate solitary wave solutions may be useful in modelling real experimental data.

physics.plasm-ph↗

arXiv2023

Accelerated magnetosonic lump wave solutions by orbiting charged space debris

The excitations of nonlinear magnetosonic lump waves induced by orbiting charged space debris objects in the Low Earth Orbital (LEO) plasma region are investigated in presence of the ambient magnetic field. These nonlinear waves are found to be governed by the forced Kadomtsev-Petviashvili (KP) type model equation, where the forcing term signifies the source current generated by different possible motions of charged space debris particles in the LEO plasma region. Different analytic lump wave solutions that are stable for both slow and fast magnetosonic waves in presence of charged space debris particles are found for the first time. The dynamics of exact pinned accelerated lump waves is explored in detail. Approximate lump wave solutions with time-dependent amplitudes and velocities are analyzed through perturbation methods for different types of localized space debris functions; yielding approximate pinned accelerated lump wave solutions. These new results may pave new direction in this field of research.

physics.plasm-ph↗

arXiv2023

Charged space debris induced nonlinear magnetosonic waves using inertial magnetohydrodynamics

The excitations of nonlinear magnetosonic waves in presence of charged space debris in the low Earth orbital plasma region is investigated taking into account effects of electron inertia in the framework of classical magnetohydrodynamics, which is also referred to as inertial magnetohydrodynamics. Magnetosonic waves are found to be governed by a forced Kadomtsev-Petviashvili equation with the forcing term representing effects of space debris particles. The dynamical behaviors of both slow and fast magnetosonic solitary waves is explored in detail. Exact accelerated magnetosonic lump solutions are shown to be stable for the entire region in parameter space of slow waves and a large region in parameter space of fast waves. In a similar way, magnetosonic curved solitary waves become stable for a small region in parameter space of fast waves. These exact solutions with special properties are derived for specific choices of debris functions. These novel results can have potential applications in scientific and technological aspects of space debris detection and mitigation.

physics.plasm-ph↗

arXiv2023

Weakly supervised segmentation with point annotations for histopathology images via contrast-based variational model

Image segmentation is a fundamental task in the field of imaging and vision. Supervised deep learning for segmentation has achieved unparalleled success when sufficient training data with annotated labels are available. However, annotation is known to be expensive to obtain, especially for histopathology images where the target regions are usually with high morphology variations and irregular shapes. Thus, weakly supervised learning with sparse annotations of points is promising to reduce the annotation workload. In this work, we propose a contrast-based variational model to generate segmentation results, which serve as reliable complementary supervision to train a deep segmentation model for histopathology images. The proposed method considers the common characteristics of target regions in histopathology images and can be trained in an end-to-end manner. It can generate more regionally consistent and smoother boundary segmentation, and is more robust to unlabeled `novel' regions. Experiments on two different histology datasets demonstrate its effectiveness and efficiency in comparison to previous models.

eess.IV↗

arXiv2021

Bending of solitonic beams modelled by coupled KMN equation in optical birefringent fibers

The dynamics of (2 + 1) dimensional optical solitonic beams in birefringent fibers without four wave mixing terms are considered using the recently introduced coupled Kundu Mukherjee Naskar (KMN) equation. The arbitrary bending of solitonic beams in this coupled optical fiber system has been discussed with various two and three dimensional plots. Such analytical results on the bending of optical pulse may pave new directions of research in this field.

nlin.PS↗

arXiv2021

Exploring the dynamics of protest against National Register of Citizens & Citizenship Amendment Act through online social media: the Indian experience

The generic fluidity observed in the nature of political protest movements across the world during the last decade weigh heavily with the presence of social media. As such, there is a possibility to study the contemporary movements with an interdisciplinary approach combining computational analytics with social science perspectives. The present study has put efforts to understand such dynamics in the context of the ongoing nationwide movement in India opposing the NRC-CAA enactment. The transformative nature of individual discontent into collective mobilization, especially with a reflective intervention in social media across a sensitive region of the nation state, is presented here with a combination of qualitative (fieldwork) and quantitative (computing) techniques. The study is augmented further by the primary data generation coupled with real-time application of analytical approaches.

cs.CY↗

arXiv2020

Propagation of non-linear waves in hot, ideal, and non-extensive quark-gluon plasma

We study the propagation of energy density perturbation in a hot, ideal quark-gluon medium in which quarks and gluons follow the Tsallis-like momentum distributions. We have observed that a non-extensive MIT bag equation of state obtained with the help of the quantum Tsallis-like distributions gives rise to a breaking wave solution of the equation dictating the evolution of energy density perturbation. However, the breaking of waves is delayed when the value of the Tsallis q parameter and the Tsallis temperature T are higher.

nucl-th↗

arXiv2020

Free surface lump wave dynamics of a saturated superfluid Helium film with nontrivial boundary condition at the substrate surface

In this article, the free surface wave dynamics of a saturated superfluid Helium film is considered under the condition that there exists a very weak downward localized superfluid flow into the substrate. For saturated film, the effect of surface tension plays a decisive role in the surface wave evolution dynamics of the system. The free surface evolution is shown to be governed by forced Kadomtsev Petviashvili-I equation, with the forcing function depending on downward superfluid velocity at the substrate surface. Exact as well as perturbative free surface lump wave solutions of the (2+1) dimensional nonlinear evolution equation are obtained and the effect of the leakage velocity function on the lump wave solutions are shown.

nlin.PS↗

arXiv2020

Novel curved solitons of integrable (2 +1) dimensional KMN equation

In this letter, the unique exact lump and topological soliton solutions of integrable (2+1) dimensional Kundu Mukherjee Naskar (KMN) equation are obtained. These solutions have an unusual property that they can get curved in the plane arbitrarily due to the presence of an arbitrary function of space(x) and time(t) in their analytic forms. Due to this special feature, the solutions can be used to model the bending of optical solitonic beam, different types of wave structures in real physical experimental conditions. This novel feature, which is a rare property for a constant coefficient completely integrable equation, arises due to the Galilean co-variance property and current like nonlinearity present in the KMN equation.

nlin.SI↗

arXiv2020

Elementary Cellular Automata along with delay sensitivity can model communal riot dynamics

This work explores the potential of elementary cellular automata to model the dynamics of riot. Here, to model such dynamics, we introduce probabilistic loss of information and delay perturbation in the updating scheme of automata to capture sociological parameters - presence of anti-riot population and organizational presence of communal forces in the rioting society respectively. Moreover, delay has also been incorporated in the model to capture the non-local interaction of neighbours. Finally, the model is verified by a recent event of riot that occurred in Baduria of West Bengal, India.

nlin.CG↗

arXiv2020

Higher dimensional localized and periodic wave dynamics in a new integrable (2+1)-dimensional Kundu-Mukherjee-Naskar model

In this article, a new integrable (2+1)-dimensional Kundu-Mukherjee-Naskar model which is a variant of the well known nonlinear Schrödinger equation is investigated. Bright-dark optical solitons along with periodic waves, complexiton and rational solutions are constructed by employing a generalized traveling wave analysis, Jacobian-elliptic function, Riccati equation and ansatz approach. Further, the dynamics of these bright/dark optical solitons and complexiton/periodic waves are studied by exploring the importance of arbitrary physical parameters with graphical demonstrations for a clear understanding. The obtained higher dimensional nonlinear wave solutions of this integrable system shall have useful applications in different physical systems including the dynamics of beam propagation in optical fibers, ion-acoustic waves in magnetized plasma and deep water oceanic rogue waves.

nlin.PS↗

arXiv2018

Novel nonlinear wave equation: regulated rogue waves and accelerated soliton solutions

A new exactly solvable (1+1)-dimensional complex nonlinear wave equation exhibiting rich ana- lytic properties has been introduced. A rogue wave (RW), localized in space-time like Peregrine RW solution, though richer due to the presence of free parameters is discovered. This freedom allows to regulate amplitude and width of the RW as needed. The proposed equation allows also an intriguing topology changing accelerated dark soliton solution in spite of constant coefficients in the equation.

nlin.PS↗

arXiv2018

A new (2+1) dimensional integrable evolution equation for an ion acoustic wave in a magnetized plasma

A new, completely integrable, two dimensional evolution equation is derived for an ion acoustic wave propagating in a magnetized, collisionless plasma. The equation is a multidimensional generalization of a modulated wavepacket with weak transverse propagation, which has resemblance to nonlinear Schrodinger (NLS) equation and has a connection to Kadomtsev-Petviashvili equation through a constraint relation. Higher soliton solutions of the equation are derived through Hirota bili- nearization procedure, and an exact lump solution is calculated exhibiting 2D structure. Some mathe- matical properties demonstrating the completely integrable nature of this equation are described. Modulational instability using nonlinear frequency correction is derived, and the corresponding growth rate is calculated, which shows the directional asymmetry of the system. The discovery of this novel (2þ1) dimensional integrable NLS type equation for a magnetized plasma should pave a new direction of research in the field.

nlin.SI↗

arXiv2018

Bending of solitons in weak and slowly varying inhomogeneous plasma

Bending of solitons in two dimensional plane is presented in the presence of weak and slowly varying inhomogeneous ion density for the propagation of ion acoustic soliton in unmagnetized cold plasma with isothermal electrons. Using reductive perturbation technique, a modified Kadomtsev- Petviashvili equation is obtained with a chosen unperturbed ion density profile. Exact solution of the equation shows that the phase of the solitary wave gets modified by a function related to the unperturbed inhomogeneous ion density causing the soliton to bend in the two dimensional plane, whereas the amplitude of the soliton remaining constant

physics.plasm-ph↗

arXiv2017

Her2 Challenge Contest: A Detailed Assessment of Automated Her2 Scoring Algorithms in Whole Slide Images of Breast Cancer Tissues

Evaluating expression of the Human epidermal growth factor receptor 2 (Her2) by visual examination of immunohistochemistry (IHC) on invasive breast cancer (BCa) is a key part of the diagnostic assessment of BCa due to its recognised importance as a predictive and prognostic marker in clinical practice. However, visual scoring of Her2 is subjective and consequently prone to inter-observer variability. Given the prognostic and therapeutic implications of Her2 scoring, a more objective method is required. In this paper, we report on a recent automated Her2 scoring contest, held in conjunction with the annual PathSoc meeting held in Nottingham in June 2016, aimed at systematically comparing and advancing the state-of-the-art Artificial Intelligence (AI) based automated methods for Her2 scoring. The contest dataset comprised of digitised whole slide images (WSI) of sections from 86 cases of invasive breast carcinoma stained with both Haematoxylin & Eosin (H&E) and IHC for Her2. The contesting algorithms automatically predicted scores of the IHC slides for an unseen subset of the dataset and the predicted scores were compared with the 'ground truth' (a consensus score from at least two experts). We also report on a simple Man vs Machine contest for the scoring of Her2 and show that the automated methods could beat the pathology experts on this contest dataset. This paper presents a benchmark for comparing the performance of automated algorithms for scoring of Her2. It also demonstrates the enormous potential of automated algorithms in assisting the pathologist with objective IHC scoring.

cs.CV↗

arXiv2016

Controlling near shore nonlinear surging waves through bottom boundary conditions

Instead of taking the usual passive view for warning of near shore surging waves including extreme waves like tsunamis, we aim to study the possibility of intervening and controlling nonlinear surface waves through the feedback boundary effect at the bottom. It has been shown through analytic result that the controlled leakage at the bottom may regulate the surface solitary wave amplitude opposing the hazardous variable depth effect. The theoretical results are applied to a real coastal bathymetry in India.

physics.flu-dyn↗

arXiv2015

Modelling rogue waves through exact dynamical lump soliton controlled by ocean currents

Rogue waves are extraordinarily high and steep isolated waves, which appear suddenly in a calm sea and disappear equally fast. However, though the Rogue waves are localized surface waves, their theoretical models and experimental observations are available mostly in one dimension(1D) with the majority of them admitting only limited and fixed amplitude and modular inclination of the wave. We propose a two-dimensional(2D), exactly solvable Nonlinear Schrödinger equation(NLS), derivable from the basic hydrodynamic equations and endowed with integrable structures. The proposed 2D equation exhibits modulation instability and frequency correction induced by the nonlinear effect, with a directional preference, all of which can be determined through precise analytic result. The 2D NLS equation allows also an exact lump solution which can model a full grown surface Rogue wave with adjustable height and modular inclination. The lump soliton under the influence of an ocean current appear and disappear preceded by a hole state, with its dynamics controlled by the current term.These desirable properties make our exact model promising for describing ocean rogue waves.

nlin.SI↗

arXiv2014

Quantum corrections to nonlinear ion acoustic wave with Landau damping

Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to presence of Landau damping terms has been calculated assuming the Landau damping parameter $α_1 = \sqrt{{m_e}/{m_i}}$ to be of the same order of the quantum parameter $Q = {\hbar^2}/({24 m^2 c^2_{s} L^2})$. The amplitude is shown to decay very slowly with time as determined by the quantum factor $ Q$.

nlin.PS↗