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DOE OSTI2024

A Hydropower facility as an Energy Water Signal Processor

In recent times, various efforts have been made to address the challenge of adequately representing hydropower systems in modeling frameworks, accounting for the lack of data to represent the multiple constraints in hydropower operation. This research is a pilot data-driven methodology for characterizing, classifying, and comparing the water-to-energy and energy-to-water signal transformations that hydropower facilities as signal processors accomplish. In this study, a Box Jenkins transfer function/noise model is used to identify the relationship between reservoir inflows and outflows. For examining the feasibility of this methodology, 5-minute fleet data for five storage and five run-of-river facilities was provided by the Tennessee Valley Authority (TVA) and transfer function models are developed. The influence of past inflow and outflow values on the current outflow decisions was investigated and summarized by examining the results of Box Jenkins methodology. Finally, dominance analysis was introduced to add value to the Box Jenkins model results and provide different stakeholders with a set of concepts to convey the functionality of hydropower.

13 HYDRO ENERGY↗

DOE OSTI2019

Novel Approach for Considering Ecosystem Services at Industrial Sites near Agricultural Lands

Natural resource damages from industrial operations have been studied for years at legacy sites, including the U.S. Department of Energy Hanford site in southeastern Washington State. Encompassing nearly 1,500 km2 (600 mi2), this site represents one of the world’s largest cleanup projects with an estimated cost exceeding $320 billion and perhaps double that. The site includes an extensive buffer zone beyond the relatively limited portion (15%) used for nuclear materials production and associated waste storage and disposal. Before Hanford existed, most of the local lands were used for agriculture, and that use has continued nearby. Historical data relevant to the natural resource damage assessment process include location-specific irrigation practices, rates of groundwater withdrawal, and sustainable yields. The potential for considering the benefit of an ecosystem service is also being explored. Undeveloped areas of the site have long provided natural habitat for a wide variety of species, including pollinators. Thus, adjacent agricultural lands have benefited from pollinator services for years. This study describes a novel approach for considering the benefit of increased crop value due to this pollinator service. The approach combines spatial data for local pollinator-dependent crops with pollinator abundance data. A production function is then applied to estimate the agro-economic value resulting from crop pollination. A preliminary analysis indicates that the increased value for apple crops alone near Hanford could be on the order of $80 million a year. The benefits from this ecosystem service could offer practical context as a complement to the assessment of natural resource damages.

MacDonell, Margaret M.↗

DOE OSTI2019

Novel Approach for Considering Ecosystem Services at Industrial Sites near Agricultural Lands - 19482

Natural resource damages from industrial operations have been studied for years at legacy sites, including the U.S. Department of Energy Hanford site in southeastern Washington State. Encompassing nearly 1,500 km{sup 2} (600 mi{sup 2}), this site represents one of the world's largest cleanup projects with an estimated cost exceeding $320 billion and perhaps double that. The site includes an extensive buffer zone beyond the relatively limited portion (15%) used for nuclear materials production and associated waste storage and disposal. Before Hanford existed, most of the local lands were used for agriculture, and that use has continued nearby. Historical data relevant to the natural resource damage assessment process include location-specific irrigation practices, rates of groundwater withdrawal, and sustainable yields. The potential for considering the benefit of an ecosystem service is also being explored. Undeveloped areas of the site have long provided natural habitat for a wide variety of species, including pollinators. Thus, adjacent agricultural lands have benefited from pollinator services for years. This study describes a novel approach for considering the benefit of increased crop value due to this pollinator service. The approach combines spatial data for local pollinator-dependent crops with pollinator abundance data. A production function is then applied to estimate the agro-economic value resulting from crop pollination. A preliminary analysis indicates that the increased value for apple crops alone near Hanford could be on the order of $80 million a year. The benefits from this ecosystem service could offer practical context as a complement to the assessment of natural resource damages. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2023

The α-WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H 2 Dissociation and Formation of Low and High Coverages

Tungsten carbide (WC) displays a Pt-like behavior in catalysis, applied in hydrogenation processes. Numerous theoretical studies have modeled the behavior and use of adsorbed hydrogen without obtaining a general picture, missing basic links between H 2 dissociation and generation of high surface coverage (Θ H >0.5 ML). Here, in this study, the capability of C- and W-terminations of the α-WC(0001) surface is analyzed to dissociate several H 2 molecules to produce coverages, Θ H , ranging from low to very high values (0.13<Θ H <2.00 ML). Density functional theory and an ab initio atomistic thermodynamic were used to achieve the conditions for H 2 dissociation. The WC–C surface has higher capacity to dissociate H 2 molecules than WC–W. However, both surfaces can reach full surface coverage, Θ H =1 ML, at mild ambient conditions, T=300 K and P=1 atm, and even up to 500 K at low and high pressures. The H-adatoms on WC–W are more labile than on WC–C. The binding of adsorbates is hindered at high Θ H , implying a need to modulate Θ H according to the application. The results give the basis to understand the capabilities of WC-based catalysts in hydrogenation-related reactions, with the advantage of WC being a hydrogen reservoir at mild practical catalytic conditions.

03 NATURAL GAS↗

DOE OSTI2025

The structure of quark mass corrections in the gg → HH amplitude at high-energy

The leading and next-to-leading order QCD predictions for Higgs boson pair production at hadron colliders suffer from a significant mass renormalisation scheme uncertainty related to the choice of the top-quark mass. The functional dependence of the result on the value of the intermediate quark mass can be understood in the high-energy limit using the Method of Regions and the tools of Soft-Collinear Effective Theory. In this work, we study the origin of the sizeable logarithmic mass corrections in the gg → HH amplitudes at leading and next-to-leading power in the limit s, |t|, |u| ≫ ${m}_t^2$ ≫ ${m}_H^2$. We argue that the mass corrections follow a predictable factorised pattern that can be exploited to simplify their computation. We present results for the leading power leading logarithmic corrections, our analysis leads to a significant reduction in the theoretical uncertainty of the double Higgs production amplitudes at scattering energies ≳ 1 TeV due to the top-quark mass scheme.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2019

Diagnosis and Prognosis of Coronary Artery Disease with SPECT and PET

Purpose of Review: Radionuclide myocardial perfusion imaging (MPI) continues to be the most reliable modality for diagnosis of hemodynamically significant coronary artery disease (CAD). The application of radionuclide MPI using single photon emission computed tomography (SEPCT) and positron emission tomography (PET) for CAD is reviewed, with emphasis on diagnosis and risk stratification. Recent Findings: Contemporary studies have reported the diagnostic and prognostic value of novel imaging protocols, employing stress-first or stress-only approach. In addition, the superior diagnostic value of PET has been established with a role of assessment of myocardial blood flow to improve risk stratification. The utility of MPI in special populations, such as the elderly, women, and diabetic patients has also been recently evaluated. Furthermore, multicenter studies have reported a similar diagnostic and prognostic value of radionuclide MPI compared with other functional and anatomical techniques for CAD. Summary: Radionuclide MPI with SPECT and PET are efficacious for diagnosis and prognosis of CAD. Its universal application in varied patient populations highlights its excellent clinical effectiveness.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2022

A reaction–diffusion model for grayscale digital light processing 3D printing

We report that digital light processing (DLP) 3D printing is an additive manufacturing process that utilizes light patterns to photopolymerize a liquid resin into a solid. Due to the accuracy of modern digital micromirror devices (DMD) and recent advances in resin chemistry, it is now possible to create functionally graded structures using different light intensity values, also known as grayscale DLP (g-DLP). Different intensities of light lead to differences in the polymer crosslinking density after curing, which ultimately produces a part with gradients of material properties. However, g-DLP is a complicated process. First, the DLP printing is a highly coupled chemical and physical process that involves light propagation, chemical reactions, species diffusion, heat transfer, volume shrinkage, and changes in mechanical behaviors of the curing resin. Second, in g-DLP, light gradients create strong in plane gradients of chemical species concentrations in the curing liquid resin due to the strong dependence of light intensity on the rate of monomer crosslinking. Furthermore, light gradients through the depth create concentration gradients due to the degree of cure dependent light absorption and the use of photoabsorbers. These complex physical features of the printing process must be understood in order to properly control printing parameters such as light exposure time, printing speed, and grayscale variations to achieve accurate mechanical properties. In this paper, a photopolymerization reaction–diffusion model is developed and used in conjunction with experiments to investigate the coupled effects of light propagation, chemical reaction rates, and species diffusion during g-DLP 3D printing. The model is implemented numerically utilizing the finite difference method and simulation results are compared to experimental findings of simple printed structures. The agreement between experimental and model predictions of simple quantities of interest, such as geometric feature sizes, shows that the model can capture the overcure due to free-radical and other species diffusion during printing when grayscale patterns are employed. This model lays the groundwork for future extensions that can incorporate more complex coupled physics such as heat transfer, volume shrinkage, and material property evolution, which are critically important in utilizing g-DLP 3D printing for the fabrication of high-performance parts which excellent geometric and material property tolerances.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Modeling the impact of GIC neutral blocking devices on distance protection relay operations for transmission lines

Geomagnetic Induced Current (GIC) blocking devices typically include a capacitor on the neutral grounding path of wye-configured transformers. This type of GIC blocking device was designed as an effective countermeasure to prevent possible damages caused on the power grid by geomagnetic storms, and by the slow-varying component of a high-altitude electromagnetic pulse (HEMP). The insertion of a capacitor in the transformer neutral impedes the establishment of GICs in lines terminated with wye-connected transformer windings. With the presence of a capacitively grounded neutral, however, it becomes important to evaluate that no adverse effects are introduced in the general grid operations. In this context, this study investigates the impact of GIC neutral blocking devices on the functionality of distance protection relays for different values of transformer neutral blocking capacitors, and at different transmission line voltages. This study was conducted with a real-time simulation platform, and the simulations were performed by introducing a phase-to-ground fault at different line locations, and by measuring the apparent impedance at the protection relay location. Finally, the results indicated that, for typical values of capacitance considered for GIC neutral blocking devices, the distance protection relay model operates properly, without requiring a modification of the relay settings.

42 ENGINEERING↗

DOE OSTI2026

Robust Automatic EXAFS First-Shell Fits

Extended X-ray absorption fine structure (EXAFS) is a widely used technique for atomic structure determination. Fourier transformation connects EXAFS in k space and R space. However, determining the appropriate k-range for the transformation can be challenging, but critical for the first-shell fit. In this study, we present an automatic method to determine the k-range using the Larch package and a Python program. The first step is to estimate spectral noise across a series of k-ranges with a fixed minimum value and identify the optimal maximum value in the k-range (k max ). The k max is determined by an empirical noise threshold that marks the point where the noise level in the Fourier transformed spectrum changes dramatically. Using the obtained k max value, the first shell is modeled to determine the minimum k value (k min ) by optimizing the background function through alignment of the spectrum with theory. The optimal k min corresponds to the point of the minimum R-factor, which quantifies the difference between the experimental and fitted spectrum. Our method was tested on various typical datasets and yielded suitable k-ranges for Fourier transformation and accurate first-shell fits. This approach helps avoid unreliable, irreproducible data analysis, especially for noisy data from diluted samples, and enables robust automatic first-shell EXAFS fitting.

EXAFS analysis↗

DOE OSTI2018

Time-Dependent Consolidation in Porous Geomaterials at In Situ Conditions of Temperature and Pressure

Analysis of quartz sandstones shows that grain-scale crushing (fracture and rearrangement) and associated sealing of fractures contribute significantly to consolidation. The crushing strength (P*) for granular material is defined by laboratory experiments conducted at strain rates of 10 -4 to 10 -5 s -1 and room temperature. Based on experiments, many sandstones would require burial depths in excess of the actual maximum burial depth to create observed microstructure and density. In this paper, we use experiments and soil mechanics principles to determine rate laws for brittle consolidation of fine-grained quartz sand to better estimate in situ failure conditions of porous geomaterials. Experiments were conducted on St. Peter sand utilizing different isostatic consolidation and creep load paths at temperatures to 200 °C and at strain rates of 10 -4 to 10 -10 s -1 . Experiment results are consistent with observed rate dependence of consolidation in soils, and P* for sand can be identified by the change in the dependence of consolidation rate with stress, allowing the extrapolation of P* determined in the laboratory to geologic rates and temperatures. Additionally, normalized P* values can be described by a polynomial function to quantify temperature, stress, and strain-rate relationships for the consolidation of porous geomaterials by subcritical cracking. At geologic loading rates, P* for fine-grained quartz sand is achieved within ~3-km burial depth, and thus, shear-enhanced compaction under nonisostatic stress can occur at even shallower depths. Finally, these results demonstrate that time and temperature effects must be considered for predicting the brittle consolidation of sediments in depositional basins, petroleum reservoirs, and engineering applications.

58 GEOSCIENCES↗

DOE OSTI2021

Activated penetrant dynamics in glass forming liquids: size effects, decoupling, slaving, collective elasticity and correlation with matrix compressibility

In this work, we employ the microscopic self-consistent cooperative hopping theory of penetrant activated dynamics in glass forming viscous liquids and colloidal suspensions to address new questions over a wide range of high matrix packing fractions and penetrant-to-matrix particle size ratios. The focus is on the mean activated relaxation time of smaller tracers in a hard sphere fluid of larger particle matrices. This quantity also determines the penetrant diffusion constant and connects directly with the structural relaxation time probed in an incoherent dynamic structure factor measurement. The timescale of the non-activated fast dissipative process is also studied and is predicted to follow power laws with the contact value of the penetrant–matrix pair correlation function and the penetrant–matrix size ratio. For long time penetrant relaxation, in the relatively lower packing fraction metastable regime the local cage barriers are dominant and matrix collective elasticity effects unimportant. As packing fraction and/or penetrant size grows, much higher barriers emerge and the collective elasticity associated with the correlated matrix dynamic displacement that facilitates penetrant hopping becomes important. This results in a non-monotonic variation with packing fraction of the degree of decoupling between the matrix and penetrant alpha relaxation times. The conditions required for penetrant hopping to become slaved to the matrix alpha process are determined, which depend mainly on the penetrant to matrix particle size ratio. By analyzing the absolute and relative importance of the cage and elastic barriers we establish a mechanistic understanding of the origin of the predicted exponential growth of the penetrant hopping time with size ratio predicted at very high packing fractions. A dynamics-thermodynamics power law connection between the penetrant activation barrier and the matrix dimensionless compressibility is established as a prediction of theory, with different scaling exponents depending on whether matrix collective elasticity effects are important. Quantitative comparisons with simulations of the penetrant relaxation time, diffusion constant, and transient localization length of tracers in dense colloidal suspensions and cold viscous liquids reveal good agreements. Multiple new predictions are made that are testable via future experiments and simulations. Extension of the theoretical approach to more complex systems of high experimental interest (nonspherical molecules, semiflexible polymers, crosslinked networks) interacting via variable hard or soft repulsions and/or short range attractions is possible, including under external deformation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Periodic Korteweg–de Vries soliton potentials generate quasisymmetric magnetic field strength in a finite plasma- β equilibrium

Quasisymmetry (QS) is a hidden symmetry of the magnetic field strength, B , that enables effective confinement of charged particles in a fully three-dimensional (3D) toroidal plasma equilibrium. Such equilibria are typically modeled by the ideal magnetohydrostatic (MHS) equations. The nonlinear, overdetermined nature of the QS MHS equations severely complicates our understanding of the interplay between 3D shaping, equilibrium properties such as pressure and rotational transform, and B . Progress has been made through expansions near the magnetic axis; however, a more comprehensive theory is desirable. Using a combination of analysis and regression on a large dataset of numerically optimized quasisymmetric stellarators, we demonstrate that there is a hidden lower dimensionality of B on a magnetic flux surface with connections to the theory of periodic solitons. We show that B on a flux surface is determined by three or at most four flux functions, each of which determines a critical value of the derivative of B along the field line. While being consistent with the near-axis models, our results are global and hold even on the last closed flux surface.

Differential geometry↗

DOE OSTI2022

Stellar multiplicity and stellar rotation: insights from APOGEE

ABSTRACT We measure rotational broadening in spectra taken by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey to characterize the relationship between stellar multiplicity and rotation. We create a sample of 2786 giants and 24 496 dwarfs with stellar parameters and multiple radial velocities from the APOGEE pipeline, projected rotation speeds vsin i determined from our own pipeline, and distances, masses, and ages measured by Sanders & Das. We use the statistical distribution of the maximum shift in the radial velocities, ΔRVmax, as a proxy for the close binary fraction to explore the interplay between stellar evolution, rotation, and multiplicity. Assuming that the minimum orbital period allowed is the critical period for Roche Lobe overflow and rotational synchronization, we calculate theoretical upper limits on expected vsin i and ΔRVmax values. These expectations agree with the positive correlation between the maximum ΔRVmax and vsin i values observed in our sample as a function of log(g). We find that the fast rotators in our sample have a high occurrence of short-period [log(P/d) ≲ 4] companions. We also find that old, rapidly rotating main-sequence stars have larger completeness-corrected close binary fractions than their younger peers. Furthermore, rapidly rotating stars with large ΔRVmax consistently show differences of 1–10 Gyr between the predicted gyrochronological and measured isochronal ages. These results point towards a link between rapid rotation and close binarity through tidal interactions. We conclude that stellar rotation is strongly correlated with stellar multiplicity in the field, and caution should be taken in the application of gyrochronology relations to cool stars.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2025

𝜂 and 𝜂′ meson production in 𝐽/𝜓 radiative decays from lattice QCD

We report on the computation of amplitudes describing the radiative decay processes 𝐽/𝜓 →𝛾⁢𝜂 and 𝐽/𝜓 →𝛾⁢𝜂′ from first principles via lattice quantum chromodynamics (QCD). Using lattices with two heavier than physical degenerate flavors of light quark where 𝑚 𝜋 ∼391 MeV, and a strange quark tuned to approximately the physical value, we compute three-point correlation functions using optimized meson operators with a range of momenta. The use of optimized operators allows access to the 𝜂′, even though it appears as an excited state, lying above the ground-state 𝜂 in the isoscalar pseudoscalar channel. Statistically precise signals are obtained in this disconnected process by averaging over large numbers of kinematically equivalent correlators. We determine transition form factors as a function of photon virtuality across the timelike region, which describe also the Dalitz processes 𝐽/𝜓 →𝑒 + ⁢𝑒 − ⁢𝜂 (′) . Significantly lower magnitudes of transition form factor for both the 𝜂 and 𝜂′ are found than those extracted from experimental data, and possible explanations for this observation are presented.

form factors↗

DOE OSTI2020

Spin dynamics in antiferromagnetic oxypnictides and fluoropnictides: LaMnAsO, LaMnSbO, and BaMnAsF

In this study, inelastic neutron scattering (INS) from polycrystalline antiferromagnetic LaMnAsO, LaMnSbO, and BaMnAsF are analyzed using a J 1 - J 2 - J c Heisenberg model in the framework of the linear spin-wave theory. All three systems show clear evidence that the nearest- and next-nearest-neighbor interactions within the Mn square lattice layer ( J 1 and J 2 ) are both antiferromagnetic (AFM). However, for all compounds studied the competing interactions have a ratio of 2 J 2 / J 1 < 1 , which favors the square lattice checkerboard AFM structure over the stripe AFM structure. The interplane coupling J c in all three systems is on the order of ~ 3 × 10 - 4 J 1 , rendering the magnetic properties of these systems with quasi-two-dimensional character. The substitution of Sb for As significantly lowers the in-plane exchange coupling, which is also reflected in the decrease of the Néel temperature, T N . Although BaMnAsF shares the same MnAs sheets as LaMnAsO, their J 1 and J 2 values are substantially different. Lastly, using density functional theory, we calculate exchange parameters J i j to rationalize the differences among these systems.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Deconvolving the components of the sign problem

Auxiliary field quantum Monte Carlo simulations of interacting fermions require sampling over a Hubbard-Stratonovich field h introduced to decouple the interactions. The weight for a given configuration involves the products of the determinant of matrices $M_σ(h)$ where σ labels the species, and hence is typically not positive definite. Indeed, the average sign $\langle \mathscr {L} \rangle$ of the determinants goes to zero exponentially with increasing spatial size and decreasing temperature for most Hamiltonians of interest. This statement, however, does not explicitly separate two possible origins for the vanishing of $\langle \mathscr {L} \rangle$. Does $\langle \mathscr {L} \rangle$ → 0 because randomly chosen field configurations have det[M(h)] < 0, or does the sign problem arise because the specific subset of configurations chosen by the weighting function have a greater preponderance of negative values? In the latter case, the process of weighting the configurations with |det[M(h)]| might steer the simulation to a region of configuration space of h where positive and negative determinants are equally likely, even though randomly chosen h would preferentially have determinants with a single dominant sign. Here in this paper, we address the relative importance of these two mechanisms for the vanishing of $\langle \mathscr {L} \rangle$ in quantum simulations.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Tuning the magnetic properties of the CrMnFeCoNi Cantor alloy

Magnetic properties of more than 20 Cantor alloy samples of varying composition were investigated over a temperature range of 5 K to 300 K and in fields of up to 70 kOe using magnetometry and muon spin relaxation. Two transitions are identified: a spin-glass-like transition that appears between 55K and 190K, depending on composition, and a ferrimagnetic transition that occurs at approximately 43K in multiple samples with widely varying compositions. The magnetic signatures at 43K are remarkably insensitive to chemical composition. A modified Curie-Weiss model was used to fit the susceptibility data and to extract the net effective magnetic moment for each sample. The resulting values for the net effective moment were either diminished with increasing Cr or Mn concentrations or enhanced with decreasing Fe, Co, or Ni concentrations. Beyond a sufficiently large effective moment, the magnetic ground state transitions from ferrimagnetism to ferromagnetism. The effective magnetic moments, together with the corresponding compositions, are used in a global linear regression analysis to extract element-specific effective magnetic moments, which are compared to the values obtained by ab initio based density functional theory calculations. Finally, these moments provide the information necessary to controllably tune the magnetic properties of Cantor alloy variants.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Perfect separation of intraband and interband excitations in PdCoO 2

The temperature dependence of the optical properties of the delafossite PdCoO 2 has been measured in the a-b planes over a wide frequency range. The optical conductivity due to the free-carrier (intraband) response falls well below the interband transitions, allowing the plasma frequency to be determined from the f-sum rule. Drude-Lorentz fits to the complex optical conductivity yield estimates for the free-carrier plasma frequency and scattering rate. Here, the in-plane plasma frequency has also been calculated using density functional theory. The experimentally determined and calculated values for the plasma frequencies are all in good agreement; however, at low temperature the optically determined scattering rate is much larger than the estimate for the transport scattering rate, indicating a strong frequency-dependent renormalization of the optical scattering rate. In addition to the expected in-plane infrared-active modes, two very strong features are observed that are attributed to the coupling of the in-plane carriers to the out-of-plane longitudinal optic modes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗