Sandia National Laboratories

Source Identification via Path-Wise Gradient Estimation

Abstract. In the context of PDE-constrained optimization theory, source identification problems traditionally entail particles emerging from an unknown source distribution inside a domain, moving according to a prescribed stochastic process, e.g., Brownian motion, and then exitin...

Rare Event Simulation of Quantum Error-Correcting Circuits

We describe a practical approach for accessing the logical failure rates of quantum error-correcting (QEC) circuits under low physical (component) failure rate regimes. Standard Monte Carlo is often the de facto approach for studying the failure rates of quantum circuits. However...

Ultrafast Dynamics of Competing Dimethyl Disulfide Photodissociation Pathways

Abstract Disulfide photochemistry impacts a wide range of chemical processes from biological UV photodamage to polymer self-healing and green photocatalysis. Despite this, the response of disulfide bonds to deep-UV light remains poorly understood. Dimethyl disulfide serves as a m...

Evaluation of liquid equation of state for deuterium oxide (D2O) and perfluorooctane (C8F18) via tamped Richtmyer–Meshkov instability experiments

Window materials in shock compression experiments maintain shock stresses in samples and enable optical velocimetry measurements of the sample–window interface. Transparent liquids present unique opportunities as negligible-strength window materials that conform to nonuniform sur...

Voxel-Based Simulation and Optimization Framework for Thermal Protection System Materials

When a spacecraft enters a planet’s atmosphere at hypersonic speed, its leading surfaces experience intense aerothermal heating. Porous ablative materials, typically composed of a fiber matrix and resin binder, are commonly used as thermal protection systems (TPS) to shield the v...

Molecular Aerosol Composition within the Atmospheric Boundary Layer at the Southern Great Plains: Seasonal Signatures from Surface to Aloft Revealed by High-Resolution Mass Spectrometry

Abstract Although aerosols within the atmospheric boundary layer (ABL) are generally considered well-mixed, how different transport mechanisms and chemical processes affect this assumption is unclear, leading to uncertainties in assessing aerosol’s impacts on radiative forcing. H...

The effect of particle size distribution on the shock-induced spread rate of particle curtains

Results are presented on the shock-induced spread rate of dense particle curtains formed using tailored particle size distributions (PSDs). The PSDs include an approximately mono-disperse, bi-disperse, narrow and broad poly-disperse distribution. Experiments were performed in the...

Efficient Generation of Entangled Photons in the Telecommunications Range Using Nonlinear Metasurfaces Integrated With ScAlN/GaN Heterostructures

ABSTRACT Entangled photons provide non‐classical correlations that enable measurement sensitivities beyond classical limits, scalable fault‐tolerant quantum computation, and fundamentally secure quantum communication, making them a foundational necessity for next‐generation quant...

Absence of Ionomer Peaks in X-ray Scattering Does Not Imply Absence of Nanophase Separation in Ionomers

Abstract A peak at low wavevectors in the X-ray scattering of hydrated, ionic polymers is typically indicative of nanophase separation between the hydrophobic and hydrophilic domains. Here we use atomistic molecular dynamics simulations to show that low intensity or absent ionome...

A neural operator for predicting vibration frequency response curves from limited data

In the design of engineered components, rigorous vibration testing is essential for performance validation and identification of resonant frequencies and amplitudes encountered during operation. Performing this evaluation numerically via machine learning has great potential to ac...

Pressure-Driven Performance and Thermal Safety Tradeoff in Solid-State Batteries

Abstract Solid-state batteries (SSBs) offer high energy density and improved safety, but their performance is limited by poor particle contact and sluggish ion transport across solid–solid interfaces. External pressure improves electrochemical performance by enhancing interfacial...

Detailed experimental investigation of the aerodynamics and blade/tower interaction of a 1.5 MW wind turbine in a downwind configuration

Abstract. We present a detailed experimental investigation of the flow details of the blade/tower interaction on a 1.5 MW wind turbine operated in a downwind configuration. The study aims to address claims of shortcomings in the downwind turbine concept, such as impulsive blade l...

Full-Field Measurement Uncertainty Quantification for Luminescence Phosphor Thermography on Surfaces in 3D Space

Abstract Background The luminescent intensity ratio (LIR) method of measuring temperature with thermographic phosphors has long been reported to exhibit sensitivities to experimental geometry as a test article moves in 3D space. Objective This work aims to evaluate the sensitivit...

Quantum-well metasurface for free-space-accessible enhanced nonlinear polarization

Abstract Nonlinear frequency conversion underpins important technologies such as telecommunications and quantum computation; however, weak nonlinearities and architectures that resist miniaturization currently limit devices’ efficiency and widespread adoption. Here we combine a b...

Cybersecurity Threat Hunting and Vulnerability Analysis Using a Neo4j Graph Database of Open Source Intelligence

Open source intelligence is a powerful tool for cybersecurity analysts to gather information both for analysis of discovered vulnerabilities and for detecting novel cybersecurity threats and exploits. Here, we present a Neo4j graph database formed by shared connections (shared su...

Topology Optimization for Fracture Resistance using Differentiable Programming and Peridynamics

Abstract Fracture resistance is a critical consideration in engineering structures, particularly in applications where material failure can have catastrophic consequences. Traditional topology optimization methods often struggle to account for fracture propagation due to the inhe...

Reinforcement learning framework for the mechanical design of microelectronic components under multiphysics constraints

Abstract This study focuses on the development of reinforcement learning-based techniques for the design of microelectronic components under multiphysics constraints. While traditional design approaches based on global optimization approaches are effective when dealing with a sma...

The AWAKEN wind farm benchmark – Part 2: Modeling results

Abstract. Accurately modeling wind farm performance in complex atmospheric flows remains a challenge. This paper presents the modeling results of the American WAKE experimeNt (AWAKEN) wind farm benchmark, a collaborative effort involving 16 research groups from academia and indus...

Accurate and Efficient Data‐Driven Partitioned Scheme for Coupled Heterogeneous Numerical Models

ABSTRACT Heterogeneous numerical models (HNMs) combine conventional discretization modules such as finite elements with nonconventional data‐driven and reduced‐order modules. HNMs can improve computational efficiency and enable simulations of multi‐physics systems in which one or...

Shear banding in simulations of polymer melts

Results from numerical simulations of polymers under shear flow are compared with predictions for shear banding based on a model coupling Rolie-Poly-like tube dynamics to the entanglement dynamics mediated by convected constraint release (CCR). CCR is controlled by a parameter β,...