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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,009 records · Page 56

A crystal plasticity finite element model embedding strain-rate sensitivities inherent to deformation mechanisms: Application to alloy AZ31

We report the fundamental power-law relationship representing the flow rule in crystal visco-plasticity ensures uniqueness in the selection of slip systems accommodating imposed plastic strain-rates. The power-law relationship also introduces an artificially high strain-rate sensitivity in crystal plasticity simulations, unless a high value of the power-law exponent is used. However, the use of high values for the exponent is limited by numerical tractability. This paper presents a numerical method implemented in a crystal plasticity finite element (CPFE) model for embedding any value of the power-law exponent reflecting the true material strain-rate sensitivity. Importantly, the method does not increase computation time involved in the simulations. The enhanced CPFE model is used to interpret and predict a complex strain-rate sensitive response and microstructural evolution of AZ31 Mg alloy. Measured values of strain-rate sensitivity for slip and twinning modes are used in the simulations. Calculations show that the model successfully captures the phenomena pertaining to the effect of changing applied strain-rate on the mechanical response including flow stress and evolution of texture and twinning for a broad range of strain-rates ranging from 10 -3 s -1 to 10 3 s -1 and loading orientations in tension and compression. It is shown that such predictions are a consequence of not only relative amounts of slip and twinning activities driven by a set of accurately characterized hardening law parameters but also values of the strain-rate sensitivities inherent to individual deformation mechanisms. Besides, the model validates the measured strain-rate dependency of deformation mechanisms while accurately reproducing the mechanical data. Hence, the model can be used to verify and further refine or infer measured strain-rate sensitivity per deformation mechanism by reproducing experimental data.

36 MATERIALS SCIENCE↗

Possibility of giant enhancement of low-frequency non-resonant Rayleigh scattering by atomic systems within dense plasmas

In this paper, we demonstrate the possibility of electron density-induced giant growth of non-resonant Rayleigh scattering of electromagnetic radiation (in the low-frequency limit) by atomic systems within dense plasmas. Non-relativistic quantum mechanical calculation is performed under electric dipole approximation, for elastic scattering of radiation by the ground states 1s of plasma-embedded hydrogen-like atomic ions treated within the framework of the ion-sphere model. The results indicate giant enhancement of the non-resonant (photon frequency ω being much smaller than the lowest resonance frequency ω{sub 1s−2p}) Rayleigh cross-section by an order of magnitude, at (atomic system-specific) high enough plasma electron densities under present consideration. The Z{sup −8}-scaling of the non-resonant Rayleigh cross-section in free and isolated H-isoelectronic sequence of ions is shown to be broken in dense plasma environments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Correlation of Surface Acoustic Wave (SAW) force myography sensor output with elbow joint torque

Accurate assessment of skeletal muscle forces and net joint torque is essential for preventing fatigue-related injuries, optimizing physical training, and monitoring disease progression in neuromuscular conditions. However, existing joint torque evaluation techniques are hindered by limited portability and high operational costs, confining their use to controlled laboratory or clinical settings. Despite substantial advances in wearable joint torque estimation systems, ongoing challenges such as power constraints, bulky wired setups, and susceptibility to environmental or motion artifacts underscore the urgent need for truly batteryless, wireless solutions deployable in real-world settings. This paper proposes a novel surface acoustic wave (SAW)-based force myography (FMG) system for noninvasive measurement of joint torque, validated against a gold-standard electromechanical dynamometer. The approach uses a single SAW sensor embedded in an armband to detect volumetric biceps brachii changes, with a second-order polynomial mapping sensor output and elbow angle to torque. Seven participants were tested in both isometric (15°–90°) and isokinetic (10°/s and 20°/s) supinated elbow flexion tasks. Under isometric conditions, subject-specific calibration achieved a normalized root-mean-square error (NRMSE) of 13.6% ± 6.0% and R 2 = 0.834 ± 0.180, while a group-level model yielded 14.4% ± 6.8% and 0.808 ± 0.208, respectively. For isokinetic trials, the group model produced an NRMSE of 24.1% ± 6.6% at 10°/s and 24.9% ± 08.9% at 20°/s, highlighting the feasibility of using a single-sensor SAW-FMG setup across different speeds. Because SAW devices support wireless, battery-free operation, the proposed system offers a pathway to portable, real-time monitoring for sports medicine, rehabilitation, and clinical diagnostics.

36 MATERIALS SCIENCE↗

Parametric Sensitivity and Uncertainty Quantification in the Version 1 of E3SM Atmosphere Model Based on Short Perturbed Parameter Ensemble Simulations

Abstract The atmospheric component of Energy Exascale Earth System Model version 1 has included many new features in the physics parameterizations compared to its predecessors. Potential complex nonlinear interactions among the new features create a significant challenge for understanding the model behaviors and parameter tuning. Using the one‐at‐a‐time method, the benefit of tuning one parameter may offset the benefit of tuning another parameter, or improvement in one target variable may lead to degradation in another target variable. To better understand the Energy Exascale Earth System Model version 1 model behaviors and physics, we conducted a large number of short simulations (three days) in which 18 parameters carefully selected from parameterizations of deep convection, shallow convection, and cloud macrophysics and microphysics were perturbed simultaneously using the Latin hypercube sampling method. From the perturbed parameter ensemble simulations and use of different skill score functions, we identified the most sensitive parameters, quantified how the model responds to changes of the parameters for both global mean and spatial distribution, and estimated the maximum likelihood of model parameter space for a number of important fidelity metrics. Comparison of the parametric sensitivity using simulations of two different lengths suggests that perturbed parameter ensemble using short simulations has some bearing on understanding parametric sensitivity of longer simulations. Results from this analysis provide a more comprehensive picture of the Energy Exascale Earth System Model version 1 behavior. The difficulty in reducing biases in multiple variables simultaneously highlights the need of characterizing model structural uncertainty (so‐called embedded errors) to inform future development efforts.

54 ENVIRONMENTAL SCIENCES↗

Savannah River Remediation Liquid Waste Operations Making the Workplace Safer - Lean and Human Performance Improvement Initiatives - 17244

The Savannah River Site, a U.S. Department of Energy facility, contracted Savannah River Remediation (SRR) to manage its liquid waste project, which is a unique, high hazard nuclear waste treatment and disposal facility consisting of 51, one million gallon underground waste tanks, a solvent extraction processing unit, a vitrification facility for the highest radioactive waste, and a grout solidification and disposal facility for a decontaminated salt solution. Our Project mission is to treat the nuclear waste and close the associated storage and treatment facilities, of which, 8 of the 51 tanks have been closed to date. Over the past three years, SRR implemented a Lean Business Management System to address site inefficiencies, aging infrastructure concerns and budget constraints. The Lean philosophy started with the work of W. Edwards Deming and his contemporaries. In more recent years the process has matured in the Toyota Production System and migrated into fields as diverse as services industries, health-care, and now the DOE complex. Like safety, continuous improvement is a fundamental core business value that starts at the top. The Lean Business System, led by our executive management team, drives quality, production and waste elimination by focusing on People using a structured Process that allows the workforce to identify and fix problems in their workplace. Many inefficiencies and quality related issues start with the desire to make systems fail-safe without defining the core requirements for which that process or program was created. This leads to added complexity and latent or inherent human performance issues embedded within our processes. While Lean can't fix all problems, a combination of strong nuclear safety culture, robust conduct of operations, active human performance improvement process, and a business practice of continuously looking for improvements leads to excellence across our industry and creates a culture that is worthy of promoting. Without strong management, our systems fail because no one sponsors or encourages those attributes we covet. Leadership starts at the top with our customer defining what provides 'value' to them, and filters down through to the organization and ultimately the workforce in day to day conduct of operations. It is imperative that our customer drives these desirable ideals through recognition and contractual requirements to encourage and support those behavioral traits that are critical to our ongoing success.This paper focuses on how the Lean Business Management System supports those attributes that we value: a strong nuclear safety culture; disciplined conduct of operations; and a culture of robust human performance and continuous improvement. These attributes in our daily work environment propel a safer, more consistent, more efficient workplace. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

A gedankenexperiment for anomalous diffusion in a charge-fluctuating dusty plasma

Brownian motion with Gaussian-distributed step-sizes is the prototype of diffusive processes with the typical scaling of the mean-square displacement linear with time. There are, however, processes scaling slower or faster in time due to differently (e.g., power-law) distributed step-sizes, commonly referred to as sub- and superdiffusion, respectively. We address the question whether there is actually a physical reason for a discrimination between normal and anomalous diffusion or whether such processes can be regarded as a special case of normal diffusion with a complicated space- and time-dependent diffusion coefficient. In order to get to the bottom of this question, we construct a numerical gedankenexperiment, which is designed to be as simple as possible and consists of dust particles embedded as test particles into a homogeneous magnetic field that randomly changes their charge. The only parameter governing the system is the ratio of the time-scales for gyration and for recharging. By performing full-orbit simulations of such particles, we are for the first time able to (i) describe a system exhibiting sub-, normal, or superdiffusion as an asymptotic behavior, i.e., not merely as an intermediate state during the evolution of the system. We (ii) observe superdiffusion for low values of the controlling parameter, normal diffusion over a wide plateau of intermediate values, and subdiffusion for high values, i.e., we found (iii) a simple system with one single and illustrative parameter controlling whether the system exhibits super-, normal, or subdiffusion. The crucial point is (iv) a competition between ballistic (particles uncharged, extreme superdiffusion) and confined (charged, extreme subdiffusion) motions. Our system is homogeneous in space and time, so that its (v) behavior cannot be described by normal diffusion with a special diffusion coefficient, and the competition is (vi) fundamentally different from a Gaussian random walk and may be regarded as one possible prototype of anomalous diffusion. We discuss briefly possible implications to space and astrophysical dusty plasma. In particular, we show that in a plasma with polydisperse dust particles, a superposition of the three regimes of the anomalous diffusion can simultaneously come into play.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Magnetocaloric properties of distilled gadolinium: Effects of structural inhomogeneity and hydrogen impurity

High-purity Gd prepared by distillation is a structurally inhomogeneous system consisting of needle-shaped crystals of cross section 0.5–2.5 μm with near-c-axis orientation embedded in a matrix of nanosized (30–100 nm) grains. By measuring the magnetocaloric effect (MCE) directly, we find that the MCE values differ markedly for the plate-shaped samples cut out of a distillate along and perpendicular to the crystals. The effect of small controlled amounts of impurity (hydrogen) on the properties of distilled Gd is further studied. We observe opposite trends in the MCE response to hydrogen charging with respect to the crystal's orientation within the samples and discuss mechanisms interrelating the unique structural morphology with the impurity behavior. As an overall assessment, the Curie temperatures of α-GdH{sub x} solid solutions increase from 291 K up to 294 K when increasing hydrogen concentration x from 0 to 0.15. Hydrogenation is found to broaden the ferromagnetic-to-paramagnetic phase transition. Hydrogen-containing specimens demonstrate reversibility of MCE at these temperatures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Study of carbon nanotube embedded honey as a resistive switching material

In this paper, natural organic honey embedded with carbon nanotubes (CNTs) was studied as a resistive switching material for biodegradable nonvolatile memory in emerging neuromorphic systems. CNTs were dispersed in a honey-water solution with the concentration of 0.2 wt% CNT and 30 wt% honey. The final honey-CNT-water mixture was spin-coated and dried into a thin film sandwiched in between Cu bottom electrode and Al top electrode to form a honey-CNT based resistive switching memory (RSM). Surface morphology, electrical characteristics and current conduction mechanism were investigated. The results show that although CNTs formed agglomerations in the dried honey-CNT film, both switching speed and the stability in SET and RESET process of honey-CNT RSM were improved. The mechanism of current conduction in CNT is governed by Ohm’s law in low-resistance state and the low-voltage range in high-resistance state, but transits to the space charge limited conduction at high voltages approaching the SET voltage.

36 MATERIALS SCIENCE↗

Distribution Feeder-Scale Fast Frequency Response via Optimal Coordination of Net-load Resources Part II: Large-Scale Demonstration

This work is the second of a two-part series in which we develop and experimentally demonstrate a hierarchical control solution for optimally coordinating thousands of deferrable loads and distributed energy resources (DERs) to provide fast frequency response (FFR) from an entire distribution feeder. In Part I, we developed and proved practical algorithms for fast, cost-based optimal dispatch and for determining the optimal amount of headroom to operate solar inverters with to support FFR dispatch while minimizing opportunity cost. Simulation results in Part I demonstrated the advantages of the hierarchical dispatch approach in being able to maintain fast solution times needed for FFR even when the problem size increases. In Part II, we implement the algorithms developed in Part I in a novel, large-scale power hardware-in-the-loop experiment including embedded controllers and more than 100 powered appliance loads and DER connected to a simulated real-world distribution system with more than 10,000 controlled devices. Experimental results from multiple scenarios confirm that the optimal FFR dispatch approach scales well and can optimally coordinate more than 10,000 net-load resources across a distribution network while achieving hardware response times within 500 ms, which is not possible using state-of-the-art optimal coordination approaches.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Addressing Risk in the Valuation of Energy Systems

Valuation is a mechanism by which potential worth of a transaction between two or more parties can be evaluated. Examples include valuation of transactive energy systems such as electric power system and building energy systems. Uncertainties can manifest while exercising a valuation methodology in the form of lack of knowledge or be inherently embedded in the valuation process. Uncertainty could also exist in the temporal dimension while planning for long-term growth. This paper discusses risk considerations associated with valuation studies in support of decision-making in the presence of such uncertainties. It is often important to have foresight of uncertain entities that can impact real-world deployments, such as the comparison or ranking of two valuation studies to determine cost-benefit impacts to multiple stakeholders. The research proposes to address this challenge through simulation and sensitivity analyses to support ‘what-if’ analysis of well-defined future scenarios. This paper describes foundational value of diagrammatic representation techniques such as unified modeling language to understand the implications of not addressing some of the risk elements encountered during the valuation process. The paper includes examples from generation resource adequacy assessment studies (e.g. loss of load) to illustrate the principles of risk in valuation.

Buildings↗

AI-Powered Knowledge Graphs for Neuromorphic and Energy-Efficient Computing

The surge in scientific literature obscures breakthroughs and hinders the discovery of new research paths. We propose an artificial intelligence (AI) powered framework using large language models (LLMs) and knowledge graphs (KGs) to automate parts of scientific discovery, focusing on energy-efficient AI circuits. Our hybrid approach combines LLMs, structured data, and ontology-based reasoning to construct a comprehensive knowledge graph that integrates insights across computational neuroscience, spiking neuron models, learning rules, architectural motifs, and neuromorphic device technologies. This multi-domain representation enables the generation of hypotheses that connect biological function with implementable, energy-efficient hardware architectures. Using KG embeddings and graph neural networks, the framework generates hypotheses for novel circuits, validates them through optimization on exascale HPC systems, and with tools like SuperNeuro and Fugu, the most promising designs will be prototyped in hardware. This open-source system aims to accelerate discoveries and bridging neuroscience with hardware innovation, drive collaboration, and unlock new opportunities in low-power AI computing.

Gautam, Ashish [ORNL]↗

Simultaneous Evolution of Gyre and Atlantic Meridional Overturning Circulation Anomalies as an Eigenmode of the North Atlantic System

Here, the authors observe an interdecadal oscillatory mode of the North Atlantic atmosphere–ocean system in a general circulation model (GFDL CM2.1) via a linear inverse model (LIM). The oscillation mechanism is mostly embedded in the subpolar gyre: anomalous advection generates density anomalies in the eastern subpolar gyre, which propagate along the mean gyre circulation and reach the subpolar gyre center around 10 years later, when associated anomalous advection of the opposite sign starts the other half cycle. While density anomalies reach the Labrador Sea deep convection region, Atlantic meridional overturning circulation (AMOC) anomalies are also induced. Both the gyre and AMOC anomalies then propagate equatorward slowly, following the advection of density anomalies. The oscillation is further demonstrated to be more likely an ocean-only mode while excited by the atmospheric forcing; in particular, it can be approximated as a linearly driven damped oscillator that is partly excited by the North Atlantic Oscillation (NAO). The slowly evolving interdecadal oscillation significantly improves and prolongs the LIM’s prediction skill of sea surface temperature (SST) evolution.

54 ENVIRONMENTAL SCIENCES↗

Software Architecture for Next Generation Beam Position Monitors at Fermilab

The Fermilab Accelerator Division / Instrumentation Department develops Beam Position Monitor (BPM) systems in-house to support its sprawling accelerator complex. Two new BPM systems have been deployed and another upgraded over the last two years. These systems are based on a combination of VME and Gigabit Ethernet connected hardware and a common Linux-based embedded software platform with modular components. The architecture of this software platform and the considerations for adapting to future machines or upgrade projects will be described.

43 PARTICLE ACCELERATORS↗

Impacts of Vehicle (In)Security

Nuclear and radioactive material is routinely transported worldwide every day. Since 2010, the complexity of the transport vehicle to support such activities has grown exponentially. Many core functions of a vehicle are now handled by small embedded computer modules with more being added each year to enhance the owner’s experience and convenience. With a system as complex as today’s automobile, the potential for cyber security issues is certain. Hackers have begun exploring this new domain with public information increasingly disseminated. Because vehicles are allowed into and around secure nuclear facilities, the potential for using a vehicle as a new cyber entry point or vector into the facility is now plausible and must be mitigated. In addition, compromising such a vehicle could aide in illicit removal of nuclear material, putting sensitive cargo at risk. Because cyber attacks can now be introduced using vehicles, cyber security, needs to be integrated into an organization’s design basis threat document. Essentially, a vehicle now extends the perimeter for which security professionals are responsible.Electronic Control Units (ECU) responsible for handling all core and ancillary vehicle functions are interconnected using the controller area network (CAN) bus. A typical CAN network in a modern automobile contains 50 or more ECUs. The CAN protocol now supports a wide variety of areas, including automotive, road transportation, rail transportation, industrial automation, power generation, maritime, military vehicles, aviation, and medical devices. In many ways, the nuclear industry is employing the CAN bus protocol or other similar broadcast serial networks. This paper will provide an overview of the current state of automobile and CAN Bus security, as well as an overview of what has been publicly disclosed by many research organizations. It will then present several hypotheses of how vehicle security issues may impact nuclear activities. An initial discussion of how a vehicle can be used as a new threat vector to penetrate secure facilities will be presented. This includes how a modern automobile can be used as the exploitation mechanism for nearby devices such as laptops, cell phones, and wireless access points. Additional discussion will highlight how vehicle security might impact transportation of nuclear material through remote exploitation of a moving vehicle. The final discussion will include what possible implications might be relative to the physical protection systems at nuclear facilities. The audience will also be given details regarding the complexity of attack, thus implying the likelihood of successful exploitation, and information on how such attacks may be mitigated. Emerging security products for automobiles will be discussed and other mitigation methods will be detailed (e.g. disabling vehicle cellular modems). As a result, the audience will have a greater understanding of how to add vehicle security as a part of a comprehensive nuclear security policy.Finally, this paper will highlight the similarities between CAN Bus and other broadcast serial bus networks such as Profibus or DeviceNet, helping educate the reader on how susceptible this type of networking is to nefarious attacks and how it might affect components connected to many different nuclear systems, including control systems, safety systems, emergency systems, and support systems.

47 OTHER INSTRUMENTATION↗

Controlled electron transfer by molecular wires embedded in ultrathin insulating membranes for driving redox catalysis

Organic bilayers or amorphous silica films of a few nanometer thickness featuring embedded molecular wires offer opportunities for chemically separating while at the same time electronically connecting photo- or electrocatalytic components. Such ultrathin membranes enable the integration of components for which direct coupling is not sufficiently efficient or stable. Photoelectrocatalytic systems for the generation or utilization of renewable energy are among the most prominent ones for which ultrathin separation layers open up new approaches for component integration for improving efficiency. Recent advances in the assembly and spectroscopic, microscopic, and photoelectrochemical characterization have enabled the systematic optimization of the structure, energetics, and density of embedded molecular wires for maximum charge transfer efficiency. The progress enables interfacial designs for the nanoscale integration of the incompatible oxidation and reduction catalysis environments of artificial photosystems and of microbial (or biomolecular)-abiotic systems for renewable energy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Thermal Overloading Risk Mitigation With a Semi-Analytical Probabilistic Model on Branch Current

A semi-analytical formulation is presented in this paper for the probability computation of branch current in multiphase systems. The developed formula is derived based on the linear power flow model in rectangular coordinates. The system uncertainty injections can be renewable energy resources or loads and are modeled using a Gaussian mixture model (GMM). The developed formula can be used to compute the line current violation probability as well as integrate into optimal power flow problem as chance-constraint relaxation. Here, the proposed formula is first compared with the Matlab embedded numerical integration function to show its performance. Besides, the semi-analytical formula is validated and compared with the Monte Carlo simulation method using the IEEE 123-bus system, EPRI Ckt5, and Ckt7 systems.

24 POWER TRANSMISSION AND DISTRIBUTION↗

ON THE NATURE OF THE HERBIG B[e] STAR BINARY SYSTEM V921 SCORPII: DISCOVERY OF A CLOSE COMPANION AND RELATION TO THE LARGE-SCALE BIPOLAR NEBULA

Belonging to the group of B[e] stars, V921 Scorpii is associated with a strong infrared excess and permitted and forbidden line emission, indicating the presence of low- and high-density circumstellar gas and dust. Many aspects of V921 Sco and other B[e] stars still remain mysterious, including their evolutionary state and the physical conditions resulting in the class-defining characteristics. In this Letter, we employ Very Large Telescope Interferometer/AMBER spectro-interferometry in order to reconstruct high-resolution ({lambda}/2B = 0.''0013) model-independent interferometric images for three wavelength bands around 1.65, 2.0, and 2.3 {mu}m. In our images, we discover a close (25.0 {+-} 0.8 mas, corresponding to {approx}29 {+-} 0.9 AU at 1.15 kpc) companion around V921 Sco. Between two epochs in 2008 and 2009, we measure orbital motion of {approx}7 Degree-Sign , implying an orbital period of {approx}35 years (for a circular orbit). Around the primary star, we detect a disk-like structure with indications for a radial temperature gradient. The polar axis of this AU-scale disk is aligned with the arcminute-scale bipolar nebula in which V921 Sco is embedded. Using Magellan/IMACS imaging, we detect multi-layered arc-shaped substructure in the nebula, suggesting episodic outflow activity from the system with a period of {approx}25 years, roughly matching the estimated orbital period of the companion. Our study supports the hypothesis that the B[e] phenomenon is related to dynamical interaction in a close binary system.

79 ASTRONOMY AND ASTROPHYSICS↗

Unbiased solar H 2 production with current density up to 23 mA cm -2 by Swiss-cheese black Si coupled with wastewater bioanode

Unbiased photoelectrochemical hydrogen production with high efficiency and durability is highly desired for solar energy storage. Here, we report a microbial photoelectrochemical (MPEC) system that demonstrated superior performance when equipped with bioanodes and black silicon photocathode with a unique “Swiss-cheese” interface. The MPEC utilizes the chemical energy embedded in wastewater organics to boost solar H 2 production, which overcomes barriers on anode H 2 O oxidation. Without any bias, the MPEC generates a record photocurrent (up to 23 mA cm -2 ) and retains prolonged stability for over 90 hours with high Faradaic efficiency (96–99%). The calculated turnover number for MoS x catalyst during a 90 h period is 495 471 with an average frequency of 1.53 s -1 . The system replaced pure water on the anode with actual wastewater and achieved waste organic removal up to 16 kg COD m -2 photocathode per day. Cost credits from concurrent wastewater treatment and low-cost design make photoelectrochemical H 2 production practical for the first time.

08 HYDROGEN↗