arXiv subjects

Apurba Sarker

Publications and source records attributed to Apurba Sarker.

6 recordsLinked to original sources

arXiv2026

Separable neural architectures as a primitive for unified predictive and generative intelligence

Intelligent systems across physics, language and perception often exhibit factorisable structure, yet are typically modelled by monolithic neural architectures that do not explicitly exploit this structure. The separable neural architecture (SNA) addresses this by formalising a representational class that unifies additive, quadratic and tensor-decomposed neural models. By constraining interaction order and tensor rank, SNAs impose a structural inductive bias that factorises high-dimensional mappings into low-arity components. Separability need not be a property of the system itself: it often emerges in the coordinates or representations through which the system is expressed. Crucially, this coordinate-aware formulation reveals a structural analogy between chaotic spatiotemporal dynamics and linguistic autoregression. By treating continuous physical states as smooth, separable embeddings, SNAs enable distributional modelling of chaotic systems. This approach mitigates the nonphysical drift characteristics of deterministic operators whilst remaining applicable to discrete sequences. The compositional versatility of this approach is demonstrated across four domains: autonomous waypoint navigation via reinforcement learning, inverse generation of multifunctional microstructures, distributional modelling of turbulent flow and neural language modelling. These results establish the separable neural architecture as a domain-agnostic primitive for predictive and generative intelligence, capable of unifying both deterministic and distributional representations.

cs.LG↗

arXiv2025

A Kernel-based Resource-efficient Neural Surrogate for Multi-fidelity Prediction of Aerodynamic Field

Surrogate models provide fast alternatives to costly aerodynamic simulations and are extremely useful in design and optimization applications. This study proposes the use of a recent kernel-based neural surrogate, KHRONOS. In this work, we blend sparse high-fidelity (HF) data with low-fidelity (LF) information to predict aerodynamic fields under varying constraints in computational resources. Unlike traditional approaches, KHRONOS is built upon variational principles, interpolation theory, and tensor decomposition. These elements provide a mathematical basis for heavy pruning compared to dense neural networks. Using the AirfRANS dataset as a high-fidelity benchmark and NeuralFoil to generate low-fidelity counterparts, this work compares the performance of KHRONOS with three contemporary model architectures: a multilayer perceptron (MLP), a graph neural network (GNN), and a physics-informed neural network (PINN). We consider varying levels of high-fidelity data availability (0%, 10%, and 30%) and increasingly complex geometry parameterizations. These are used to predict the surface pressure coefficient distribution over the airfoil. Results indicate that, whilst all models eventually achieve comparable predictive accuracy, KHRONOS excels in resource-constrained conditions. In this domain, KHRONOS consistently requires orders of magnitude fewer trainable parameters and delivers much faster training and inference than contemporary dense neural networks at comparable accuracy. These findings highlight the potential of KHRONOS and similar architectures to balance accuracy and efficiency in multi-fidelity aerodynamic field prediction.

cs.LG↗

arXiv2025

Process Microstructure Coupling in Reduced Gravity Laser Welding via Open-Source Multiphysics Simulation Framework

Supplying spare parts from Earth for in space repair is economically prohibitive and logistically slow, posing a major barrier to sustainable space operations. As lunar and Martian missions accelerate in the coming decades, the feasibility of in-situ repair methods, particularly laser based welding, must be rigorously evaluated. The micro scale physics governing weld quality are fundamentally altered by variations in gravity and ambient pressure, yet their coupled influence across different welding regimes remains poorly understood. This work introduces a fully open-source thermo-fluid-microstructure modeling framework with computational fluid dynamics (CFD) and cellular automata (CA) to quantify how gravitational conditions reshape weld pool behavior across multiple welding regimes and spatial scales. The framework further enables prediction of the resulting microstructure from imposed process parameters, providing an accessible pathway for future research in in space manufacturing (ISM). As a demonstration, the article analyzes laser welding of Al6061 across three process regimes (conduction, transition, and keyhole) and four gravitational environments (Earth, Moon, Mars, and International Space Station (ISS)). Analysis reveals that reduced gravity suppresses buoyancy-driven convection, thereby altering melt pool geometries. Vacuum conditions increase laser energy deposition, while microgravity promotes equiaxed grain formation via reduced melt convection. The framework captures keyhole dynamics, thermal histories, and grain morphologies with high fidelity, validated against experimental data. These findings establish process microstructure relationships critical for reliable metallic fabrication in space and provide a reproducible platform for future in-space manufacturing research.

physics.flu-dyn↗

arXiv2025

Gravity and Composition Modulated Solidification and Mechanical Properties of Al-Cu Nanostructures

The future of space exploration and human settlement beyond Earth hinges on a deeper understanding of in space manufacturing processes. The unique physical conditions and scarcity of experimental data demand robust computational models to investigate the atomic scale physics of solidification. This work presents a molecular dynamics (MD) model to examine the solidification behavior of the Al Cu binary alloy, focusing on the influence of varying compositions and gravity levels (Earth, Lunar, Martian, and microgravity) on atomistic solidification mechanisms and the resulting mechanical properties specifically, hardness of as solidified nanostructures. Hardness is evaluated via nanoindentation simulations. The study confirms that gravitational forces significantly affect the solidification pathways of Al Cu alloys. Notably, by tuning alloy composition, the influence of gravity can be modulated and in some cases, even reversed. Moreover, hardness exhibits a coupled dependence on both composition and gravity, offering a promising avenue for bottom-up design of components tailored for extraterrestrial environments. The article delves into the nanoscale physical mechanisms underlying these phenomena and outlines future directions for extending this modeling framework to broader applications.

cond-mat.mtrl-sci↗

arXiv2024

Efficient Aircraft Design Optimization Using Multi-Fidelity Models and Multi-fidelity Physics Informed Neural Networks

Aircraft design optimization traditionally relies on computationally expensive simulation techniques such as Finite Element Method (FEM) and Finite Volume Method (FVM), which, while accurate, can significantly slow down the design iteration process. The challenge lies in reducing the computational complexity while maintaining high accuracy for quick evaluations of multiple design alternatives. This research explores advanced methods, including surrogate models, reduced-order models (ROM), and multi-fidelity machine learning techniques, to achieve more efficient aircraft design evaluations. Specifically, the study investigates the application of Multi-fidelity Physics-Informed Neural Networks (MPINN) and autoencoders for manifold alignment, alongside the potential of Generative Adversarial Networks (GANs) for refining design geometries. Through a proof-of-concept task, the research demonstrates the ability to predict high-fidelity results from low-fidelity simulations, offering a path toward faster and more cost effective aircraft design iterations.

cs.LG↗

arXiv2024

Graph neural network framework for energy mapping of hybrid monte-carlo molecular dynamics simulations of Medium Entropy Alloys

Machine learning (ML) methods have drawn significant interest in material design and discovery. Graph neural networks (GNNs), in particular, have demonstrated strong potential for predicting material properties. The present study proposes a graph-based representation for modeling medium-entropy alloys (MEAs). Hybrid Monte-Carlo molecular dynamics (MC/MD) simulations are employed to achieve thermally stable structures across various annealing temperatures in an MEA. These simulations generate dump files and potential energy labels, which are used to construct graph representations of the atomic configurations. Edges are created between each atom and its 12 nearest neighbors without incorporating explicit edge features. These graphs then serve as input for a Graph Convolutional Neural Network (GCNN) based ML model to predict the system's potential energy. The GCNN architecture effectively captures the local environment and chemical ordering within the MEA structure. The GCNN-based ML model demonstrates strong performance in predicting potential energy at different steps, showing satisfactory results on both the training data and unseen configurations. Our approach presents a graph-based modeling framework for MEAs and high-entropy alloys (HEAs), which effectively captures the local chemical order (LCO) within the alloy structure. This allows us to predict key material properties influenced by LCO in both MEAs and HEAs, providing deeper insights into how atomic-scale arrangements affect the properties of these alloys.

cond-mat.mtrl-sci↗