arXiv subjects

Soham Dutta

Publications and source records attributed to Soham Dutta.

5 recordsLinked to original sources

arXiv2026

Non-reciprocity drives a Brownian dimer out of equilibrium

We consider the minimal model of a two dimensional Brownian dimer consisting of two overdamped monomers, trapped in an isotropic harmonic potential and mutually coupled by a non-reciprocal harmonic spring that violates Newton's action-reaction principle. We have shown that the non-reciprocal interaction alone can drive the system far from equilibrium, in the absence of any external time dependent drive and being in contact with a single thermal bath. The exact steady state probability distribution and current are explicitly calculated for the zero-rest-length limit of the spring, which eventually maps our model to another non-equilibrium phenomenon, called Brownian gyration. For a spring with finite rest length, these quantities are calculated numerically.

cond-mat.stat-mech↗

arXiv2026

Brownian gyration of an inertial ellipsoid

Recent studies on Brownian gyration (BG) have focused primarily on spherically symmetric particles under overdamped conditions. To explore BG in the underdamped regime with a spherically asymmetric particle, we investigate the inertial dynamics of a microscopic ellipsoid in a dissipative medium. The particle is confined in a spherically asymmetric trap and simultaneously coupled to two distinct thermal reservoirs. This configuration drives the system into a nonequilibrium steady state (NESS) characterised by BG, which is quantified by the mean and fluctuation of the particle's specific angular momentum. Using inertial Langevin dynamics, we systematically analyze how this microscopic gyration depends not merely on the trap asymmetry and temperature difference, but also on the particle's intrinsic physical properties like shape and axial orientation, besides inertia. Our study uncovers fundamental differences between the gyration of spherical and non-spherical particles in overdamped as well as underdamped conditions, at microscopic scales. These findings provide key insights for optimizing Brownian gyration across a broader landscape of experimentally tuneable parameters.

cond-mat.stat-mech↗

arXiv2025

A Low-Cost UAV Deep Learning Pipeline for Integrated Apple Disease Diagnosis,Freshness Assessment, and Fruit Detection

Apple orchards require timely disease detection, fruit quality assessment, and yield estimation, yet existing UAV-based systems address such tasks in isolation and often rely on costly multispectral sensors. This paper presents a unified, low-cost RGB-only UAV-based orchard intelligent pipeline integrating ResNet50 for leaf disease detection, VGG 16 for apple freshness determination, and YOLOv8 for real-time apple detection and localization. The system runs on an ESP32-CAM and Raspberry Pi, providing fully offline on-site inference without cloud support. Experiments demonstrate 98.9% accuracy for leaf disease classification, 97.4% accuracy for freshness classification, and 0.857 F1 score for apple detection. The framework provides an accessible and scalable alternative to multispectral UAV solutions, supporting practical precision agriculture on affordable hardware.

cs.CV↗

arXiv2025

Stochastic Heat Engine Using a Single Brownian Ellipsoid

Optical tweezers can confine position as well as orientation of a Brownian particle by simultaneously exerting restoring force and torque on it. Here we have proposed the theoretical model of a microscopic Stirling engine, using a passive Brownian ellipsoid as its working substance. The position and the orientation degrees of freedom (DoF) of the ellipsoid in two dimensions (2D), both being confined harmonically by the tweezers, are coupled to a hot and a cold thermal bath time-periodically. The stiffness of the force confinement is also time-periodic such that it resembles a piston-like protocol which drives the Brownian ellipsoid through the strokes of a Stirling cycle. The ellipsoid takes heat from the hot bath and partially converts it into useful thermodynamic work. The extracted work and input heat shows explicit dependence on the shape of the working substance as well as its orientational bias. The operational characteristics of the anisotropic Stirling engine is analyzed using the variance in work and efficiency (in the quasi-static regime), where the latter is bounded by both the Carnot limit as well as the isotropic benchmark. Several ways have been proposed to yield maximum efficiency at a minimum fluctuation in the output. The dissipative coupling between the position and orientation of the ellipsoid, that arises due to its spherical-asymmetry (or, shape anisotropy) and a finite mean orientation, plays an important role to optimize the engine characteristics. Finally, we have analytically explored the slightly anisotropic regime, where the coupling is linearized by suitably tuning the system parameters. The average extracted work has also been calculated in this case, which shows an excellent agreement with the numerical results of the fully anisotropic system, when subjected to the stipulated range of parameters.

cond-mat.stat-mech↗

arXiv2023

Microscopic Gyration with Dissipative Coupling

Microscopic gyrators, including Brownian gyrators (BGs), require anisotropic fluctuations to perform gyration. It produces a finite current, driving the system out of equilibrium. In a typical BG set-up with an isotropic colloidal particle, the anisotropy sets in by the coupling among space dimensions via an externally applied anisotropic potential confining the particle and the difference between the temperatures along various space dimensions. The coupling is conservative. Here, contrary to a typical BG, first we consider an over-damped, anisotropic colloidal particle (a Brownian ellipsoid), trapped in an isotropic harmonic potential in two dimensions (2D). The space dimensions are coupled by the difference between the longitudinal and transverse frictional drags experienced by the ellipsoid, together with a finite tilt in its orientation due to its chirality. The coupling is dissipative. They are intrinsic properties of the particle. We have shown that this dissipative coupling can generate enough anisotropic fluctuations to perform a steady-state gyration in the Brownian scale. Next, going beyond BG, we have considered an inertial, granular, chiral ellipsoid in 2D, subjected to athermal, anisotropic fluctuations. There is no trapping force confining the granular ellipsoid. However, the coupling between the velocity components of the granular ellipsoid is still dissipative. We have shown that being assisted by the dissipative coupling and the anisotropic fluctuations, the inertial, granular ellipsoid can also perform gyration in 2D. We have also shown that the dominant contribution towards the gyrating frequency can be attributed to the Coriolis force acting on the granular ellipsoid. Hence, the gyrator in the granular scale is also a tiny autonomous machine that generates a directed motion (gyration) from fluctuations. Although there are fundamental differences between the two.

cond-mat.stat-mech↗