arXiv subjects

Anshu Sharma

Publications and source records attributed to Anshu Sharma.

8 recordsLinked to original sources

arXiv2026

SPECTRA: A Physics-informed Digital Twin for Real-time Structural Anomaly Inference under Operational Variability

Structural health monitoring is moving from damage detection alone towards real-time decision support for ageing and safety-critical infrastructure. This shift requires monitoring methods that can separate true structural change from benign environmental and operational variability, while remaining interpretable to engineers. This paper presents SPECTRA, a physics-informed eigen-compressed digital twin framework for real-time structural anomaly inference. The framework combines a healthy structural twin, eigen-compressed dynamic representation, full-order twin innovation, residual-augmented spectral features, kernel principal component analysis, and a persistent decision rule. The central idea is that structural anomalies are inferred not from statistical features alone, but from disagreement between the measured response and a physics-informed healthy twin. The method is assessed through seven numerical benchmarks: smooth Duffing-type nonlinear drift, sudden stiffness loss, gradual stiffness degradation, bilinear breathing stiffness, environmental and operational variability-confounded local damage, local damping loss, and an operational-only negative-control case. The results show that SPECTRA detects abrupt, gradual, nonlinear and damping-related damage mechanisms, while avoiding persistent false alarms under operational variability alone. Across the accepted benchmark suite, the persistent decision rule gives zero pre-damage persistent false alarms, finite detection delay in damage cases, and zero persistent alarms in the no-damage negative-control case. The framework provides a reproducible route for testing physics-informed anomaly inference before deployment in infrastructure digital twins.

cs.CE↗

arXiv2026

A Formal Semantics of C with OpenMP Parallelism (Extended Version)

OpenMP is a popular parallelization framework that lets users transform sequential code into parallel code with a few simple annotations. Unfortunately, it is also easy to inadvertently introduce errors by adding OpenMP pragmas into otherwise correct programs, including both logic errors and race conditions. We present a formal semantics for C code with OpenMP directives, building on the C semantics of the CompCert verified compiler and its extension to concurrency. Our semantics captures subtle interactions between OpenMP directives and variable state that have been obscured by previous OpenMP semantics, and provides a basis for detecting undesired behaviors introduced by incorrect annotations: in particular, any successful execution is guaranteed to be free of data races.

cs.DC↗

arXiv2026

A Physics-Aware Variational Graph Autoencoder for Joint Modal Identification with Uncertainty Quantification

Reliable modal identification from output-only vibration data remains a challenging problem under measurement noise, sparse sensing, and structural variability. These challenges intensify when global modal quantities and spatially distributed mode shapes must be estimated jointly from frequency-domain data. This work presents a physics-aware variational graph autoencoder, termed UResVGAE, for joint modal identification with uncertainty quantification from power spectral density (PSD) representations of truss structures. The framework represents each structure as a graph in which node attributes encode PSD and geometric information, while edges capture structural connectivity. A residual GraphSAGE-based encoder, attention-driven graph pooling, and a variational latent representation are combined to learn both graph-level and node-level modal information within a single, unified formulation. Natural frequencies and damping ratios are predicted through evidential regression, and full-field mode shapes are reconstructed through a dedicated node-level decoder that fuses global latent information with local graph features. Physical consistency is promoted via mode-shape reconstruction and orthogonality regularisation. The framework is assessed on numerically generated truss populations under varying signal-to-noise ratios and sensor availability. Results demonstrate accurate prediction of natural frequencies, damping ratios, and mode shapes, with high modal assurance criterion values and stable performance under noisy and sparse sensing conditions. Reliability analysis indicates that the predictive uncertainty is broadly consistent with empirical coverage. The proposed framework offers a coherent and physically grounded graph-based route for joint modal identification with calibrated uncertainty from frequency-domain structural response data.

cs.CE↗

arXiv2026

A Cloud-based Multi-Agentic Workflow for Science

As Large Language Models (LLMs) become ubiquitous across various scientific domains, their lack of ability to perform complex tasks like running simulations or to make complex decisions limits their utility. LLM-based agents bridge this gap due to their ability to call external resources and tools and thus are now rapidly gaining popularity. However, coming up with a workflow that can balance the models, cloud providers, and external resources is very challenging, making implementing an agentic system more of a hindrance than a help. In this work, we present a domain-agnostic, model-independent workflow for an agentic framework that can act as a scientific assistant while being run entirely on cloud. Built with a supervisor agent marshaling an array of agents with individual capabilities, our framework brings together straightforward tasks like literature review and data analysis with more complex ones like simulation runs. We describe the framework here in full, including a proof-of-concept system we built to accelerate the study of Catalysts, which is highly important in the field of Chemistry and Material Science. We report the cost to operate and use this framework, including the breakdown of the cost by services use. We also evaluate our system on a custom-curated synthetic benchmark and a popular Chemistry benchmark, and also perform expert validation of the system. The results show that our system is able to route the task to the correct agent 90% of the time and successfully complete the assigned task 97.5% of the time for the synthetic tasks and 91% of the time for real-world tasks, while still achieving better or comparable accuracy to most frontier models, showing that this is a viable framework for other scientific domains to replicate.

cs.CL↗

arXiv2025

Investigating dimensionally-reduced highly-damped systems with multivariate variational mode decomposition: An experimental approach

Structural health monitoring (SHM) is an essential engineering field aimed at ensuring the safety and reliability of civil infrastructures. This study proposes a methodology using multivariate variational mode decomposition (MVMD) for damage detection and modal identification. MVMD decomposes multi-sensor vibration responses into intrinsic modal components, facilitating the extraction of natural frequencies and damping ratios by analyzing amplitude decay in the identified modes. Mode shapes are determined through peak-normalization of Fourier spectra corresponding to each mode. The methodology is further applied to detect damage by identifying changes in the extracted modal parameters and spatial features of the structure. The proposed approach enables damage detection by tracking variations in modal parameters and spatial structural characteristics. To validate its efficacy, the methodology is applied to a benchmark eight-degree-of-freedom (8-DOF) system from Los Alamos National Laboratory (LANL), demonstrating its robustness in identifying structural damage under non-stationary excitation and narrowband frequency content. The results confirm that MVMD provides a reliable and adaptable framework for modal analysis and damage assessment in complex infrastructure systems, addressing key challenges such as environmental variability and practical scenarios.

stat.AP↗

arXiv2025

Validating Quantum State Preparation Programs (Extended Version)

One of the key steps in quantum algorithms is to prepare an initial quantum superposition state with different kinds of features. These so-called state preparation algorithms are essential to the behavior of quantum algorithms, and complicated state preparation algorithms are difficult to develop correctly and effectively. This paper presents Pqasm: a high-assurance framework implemented with the Coq proof assistant, allowing us to certify our Pqasm tool to correctly reflect quantum program behaviors. The key in the framework is to reduce the program correctness assurance of a program containing a quantum superposition state to the program correctness assurance for the program state without superposition. The reduction allows the development of an effective testing framework for testing quantum state preparation algorithm implementations on a classical computer - considered to be a hard problem with no clear solution until this point. We utilize the QuickChick property-based testing framework to test state preparation programs. We evaluated the effectiveness of our approach over 5 case studies implemented using Pqasm; such cases are not even simulatable in the current quantum simulators.

quant-ph↗

arXiv2024

When Fire Attacks: How does Concrete Stand up to Heat ?

Fire is a process that generates both light and heat, posing a significant threat to life and infrastructure. Buildings and structures are neither inherently susceptible to fire nor completely fire-resistant; their vulnerability largely depends on the specific causes of the fire, which can stem from natural events or human-induced hazards. High temperatures in structures can lead to severe health risks for those directly affected, discomfort due to smoke, and compromised safety if the structure fails to meet safety standards. Elevated temperatures can also cause significant structural damage, becoming the primary cause of casualties, economic losses, and material damage. This study aims to investigate the thermal and structural behavior of concrete beams when exposed to extreme fire conditions. It examines the effects of different temperatures on plain and reinforced concrete (PCC and RCC, respectively) using finite element method (FEM) simulations. Additionally, the study explores the performance of various concrete grades under severe conditions. The analysis reveals that higher-grade concrete exhibits greater displacement, crack width, stress, and strain but has lower thermal conductivity compared to lower-grade concrete. These elevated temperatures can induce severe stresses in the concrete, leading to expansion, spalling, and the potential failure of the structure. Reinforced concrete, on the other hand, shows lower stress concentrations and minimal strain up to 250°C. These findings contribute to the existing knowledge and support the development of improved fire safety regulations and performance-based design methodologies.

cs.CE↗

arXiv2022

Dwelling Type Classification for Disaster Risk Assessment Using Satellite Imagery

Vulnerability and risk assessment of neighborhoods is essential for effective disaster preparedness. Existing traditional systems, due to dependency on time-consuming and cost-intensive field surveying, do not provide a scalable way to decipher warnings and assess the precise extent of the risk at a hyper-local level. In this work, machine learning was used to automate the process of identifying dwellings and their type to build a potentially more effective disaster vulnerability assessment system. First, satellite imageries of low-income settlements and vulnerable areas in India were used to identify 7 different dwelling types. Specifically, we formulated the dwelling type classification as a semantic segmentation task and trained a U-net based neural network model, namely TernausNet, with the data we collected. Then a risk score assessment model was employed, using the determined dwelling type along with an inundation model of the regions. The entire pipeline was deployed to multiple locations prior to natural hazards in India in 2020. Post hoc ground-truth data from those regions was collected to validate the efficacy of this model which showed promising performance. This work can aid disaster response organizations and communities at risk by providing household-level risk information that can inform preemptive actions.

cs.LG↗