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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 541 records · Page 30
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DOE OSTI2021

The Cosmological Bootstrap: Spinning correlators from symmetries and factorization

We extend the cosmological bootstrap to correlators involving massless spinning particles, focusing on spin-1 and spin-2. In de Sitter space, these correlators are constrained both by symmetries and by locality. In particular, the de Sitter isometries become conformal symmetries on the future boundary of the spacetime, which are reflected in a set of Ward identities that the boundary correlators must satisfy. We solve these Ward identities by acting with weight-shifting operators on scalar seed solutions. Using this weight-shifting approach, we derive three- and four-point correlators of massless spin-1 and spin-2 fields with conformally coupled scalars. Four-point functions arising from tree-level exchange are singular in particular kinematic configurations, and the coefficients of these singularities satisfy certain factorization properties. We show that in many cases these factorization limits fix the structure of the correlators uniquely, without having to solve the conformal Ward identities. The additional constraint of locality for massless spinning particles manifests itself as current conservation on the boundary. We find that the four-point functions only satisfy current conservation if the s, t, and u-channels are related to each other, leading to nontrivial constraints on the couplings between the conserved currents and other operators in the theory. For spin-1 currents this implies charge conservation, while for spin-2 currents we recover the equivalence principle from a purely boundary perspective. For multiple spin-1 fields, we recover the structure of Yang--Mills theory. Finally, we apply our methods to slow-roll inflation and derive a few phenomenologically relevant scalar-tensor three-point functions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

QCD factorization for hadronic quarkonium production at high $p_T$

Heavy quarkonium production at high transverse momentum ( p_T p T ) in hadronic collisions is explored in the QCD factorization approach. We find that the leading power in the 1/p_T 1 / p T expansion is responsible for high p_T p T regime, while the next-to-leading power contribution is necessary for the low p_T p T region. We present the first numerical analysis of the scale evolution of coupled twist-2 and twist-4 fragmentation functions (FFs) for heavy quarkonium production and demonstrate that the QCD factorization approach is capable of describing the p_T p T spectrum of hadronic J/\psi J / ψ production at the LHC.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Power Sector Transformation Pathways: Exploring Objectives, Factors, and Technology Innovations to Inform Power Sector Pathway Decisions

The power and heating sectors are responsible for around 30% of global CO2 emissions and this share is likely to grow as countries move towards electrification of the transportation and building sectors. Therefore, enabling forward-thinking, long term strategies in the power sector is a crucial area for international collaboration and support. The rapid transition of power systems toward modern, low-carbon pathways and technologies will be necessary to meet key climate goals while also enabling other critical objectives such as economic development, energy access, and energy system resiliency, among others. Many developed and developing countries are well-poised to champion power sector transformation (PST), however, further support is needed to identify pathways and implement critical near and long-term actions. To address this need, the Low Emission Development Strategies Global Partnership (LEDS GP) together with an expert team including Agora Energiewende, Energy Innovation, European Climate Foundation, Fraunhofer Institute for Systems and Innovation Research , Prayas Energy Group and LEDS Latin America and Caribbean Platform, developed a framework identifying four key pathways that can be integrated and combined to support low-carbon PST. These four pathways are: (1) Distributed Energy Resource Revolution, (2) Bulk Power Transformation, (3) Transmission and Distribution Interactivity, and (4) Distributed Transactional Future. To support exploration of pathways, this study examines PST objectives and factors that may lead countries or jurisdictions to place a greater relative emphasis on certain pathways as well as a framework and complementary tool for considering the emphasis in a hands on manner. The report provides case studies on application of the approach to bring life to the topic. The case studies include Haiti, Kenya, Mexico, Southeast Asia, and the European Union, among others. The report also presents actions to-be-taken in the near-, medium- and long-term to support the realization of pathways and long-term transformation of the power sector. The report, together with a complementary spreadsheet tool developed under the effort, can be used to enable stakeholder engagement and visioning for the power sector over the long-term, taking into account key factors and potential innovations. It can also be used to understand and inform relevant analysis tools and models based on which pathways are emphasized, and to identify key actions in the near- and medium-term to avoid lock-in of carbon-intensive technologies.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2020

(U) Endpoint Energy and Scintillator Geometry Effects on the Swank Factor, Quantum Efficiency, and DQE(0) for High-Energy Radiography

High-energy radiography is used to image imploding materials to better understand weapon design and performance. The Enhanced Capabilities for Subcritical Experiments (ECSE) is a new facility proposal that aims to collect radiographic images of nuclear material. As part of the facility design, we aim to optimize data quality and radiographic performance by investigating different detector designs. We addressed design decisions by simulating different scintillator designs using M CNP6 and calculated the quantum efficiency, Swank factor, and detective quantum efficiency at zero-frequency (DQE(O)). First, we investigated the effects of the x-ray endpoint energy on the detector response. We generated three x-ray spectra with endpoint energies of 20 MeV, 22 MeV, and 24 MeV. The three raw spectra were filtered using the Dual-Axis Radiographic Hydrodynamic Test facility (DARHT) line-of-sight materials along with 1) flat field filtration using 7 cm tungsten alloy in the bullnose and 2) an FTO with 4 plates. The scatter-to-direct radiation ratio was much larger for FTO with 4 plates (50-60%) compared to the flat field with 7 cm of bullnose material (8%). We used these filtered spectra to calculate the detector response for the original DARHT segmented scintillator design. We found that the endpoint energy and filtration had a negligible effect on the detector response. The quantum efficiency was 0.63, the Swank factor was 0.84, and the DQE(O) was 0.53 for all six spectra.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Calculation of Glycolate Concentration Factors Across the 242-25H (3H) Evaporator System

Two models were developed to predict glycolate concentration factors across the 242-25H (3H) Evaporator system. The first model, identified as the Unrestricted Evaporation Model, was designed to evaluate concentration of typical 3H feed material to relatively high densities in order to calculate the concentration factor of glycolate in a given feed stream. This model may be used to understand the potential of glycolate to concentrate from a generic feed material through the 3H system. The second model, identified as the Holistic Evaporation Model, was designed to evaluate the evaporation of dilute, glycolate-containing Defense Waste Processing Facility (DWPF) waste with the requirement that high silicon concentrations typical of recycle material require dilution to adhere to current technical safety requirements. This model may be used to understand the potential of glycolate from DWPF recycle material to concentrate as a result of feeding through the 3H system.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Machine learning to identify geologic factors associated with production in geothermal fields: A casestudy using 3D geologic data, Brady geothermal field, Nevada

In this paper, we present an analysis using unsupervised machine learning (ML) to identify the key geologic factors that contribute to the geothermal production in the Brady geothermal field. Brady is a hydrothermal system in northwestern Nevada that supports both electricity production and direct use of hydrothermal fluids. Transmissive fluid flow pathways are relatively rare in the subsurface but are critical components of hydrothermal systems like Brady and many other types of fluid flow systems in fractured rock. The ML method, non-negative matrix factorization with k-means clustering (NMFk), is applied to a library of fourteen 3D geologic characteristics hypothesized to control hydrothermal circulation in the Brady geothermal field. Our results indicate the macro-scale faults and a local step-over in the fault system preferentially occur along with production wells when compared to injection wells and non-productive wells. We infer that these are the key geologic characteristics that control the through-going hydrothermal transmission pathways at Brady. Our results demonstrate 1) the specific geologic controls on the Brady hydrothermal system and 2) the efficacy of pairing ML techniques with 3D geologic characterization to enhance the understanding of subsurface processes.

15 GEOTHERMAL ENERGY↗
DOE OSTI2021

PV Reference Cells for Outdoor Use: An Investigation of Calibration Factors

Reference cells are widely used in the photovoltaic (PV) industry to measure irradiance. For field applications and outdoor use, a variety of products are on the market, and they are often perceived as a low-cost alternative to thermopile radiometers. But reference cell characteristics differ substantially from the latter, therefore measurements made by one category of instrument cannot be substituted for or directly compared with the other. The National Renewable Energy Laboratory's (NREL's) Solar Radiation Research Laboratory is currently in a multiyear effort to develop guidance and recommendations for the design and use of outdoor reference cells, with a view to reducing inconsistencies and measurement uncertainty. The core of this effort is the long-term deployment of 39 units of 10 distinct types made by 6 manufacturers. This report compares the calibration factors provided by manufacturers - which most users rely upon - to those measured at a high level of accuracy by NREL's Cell Lab. It also reports on the application of the Broadband Outdoor Radiometer Calibration (BORCAL) method to reference cells. As a group, the factory calibrations for the crystalline silicon cells showed a small positive bias of +0.7%, with a tight distribution around this value. This is a very good result for the manufacturers. The two World Photovoltaic Scale cells constituted outliers, with a mean deviation of -0.8%, which is still within the reported uncertainty ranges. The data collected during the BORCAL procedures show a strong and systematic fluctuation of the apparent responsivity of the reference cells over the course of a day, which was anticipated. Consequently, the standard BORCAL R@45 calibration factors underestimated the reference cell responsivities by 1%-4%. An alternate responsivity indicator was developed, R'@30, incorporating adjustments for temperature response, spectral response, and directional response. This reduced the mean deviation to -0.4% compared to the Cell Lab. Further, two independent BORCAL sessions were able to produce the same values to within ±0.2%. This could be a viable approach for verifying reference cells using existing BORCAL infrastructure, for example, to evaluate their long-term stability. The daily profiles of responsivity obtained during the BORCAL sessions (provided in Appendix A) show clear patterns of differences between models, which provides evidence that their directional responses differ from each other; thus, two sensors that are calibrated correctly might give the same reading at 30° zenith angle but systematically different readings at 60°. The impact of these inconsistencies in field operation will be quantified using the long-term observations started in 2020.

14 SOLAR ENERGY↗
DOE OSTI2021

Human Factors and Reliability [Slides]

People come to work, wanting, expecting, and planning to do a good job, but people tend to do what makes sense to them in their context. Understanding basic human factors and establishing controls to prevent common human factors issues helps ensure that a criticality accident will never happen again.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2022

High Brightness High Duty Factor Negative Ion Beam Injector [Slides]

The high brightness negative ion injector combines multiple individual low-duty-factor H- ion sources (multiplexing) in a manner that allows flexibility in final pulse format and beam duty factor up to CW and increases reliability by eliminating an otherwise single-point failure usually associated with using a single ion source. The multiplexing of multiple beams in new injector system also preserves the beam quality of each individual ion source, eliminating a significant source of beam quality degradation usually associated with combining beams.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Factorized approach to radiative corrections for inelastic lepton-hadron collisions [Slides]

We propose a new factorized approach to QED radiative corrections (RCs) in inclusive and semi-inclusive lepton-hadron deep-inelastic scattering. The method allows the systematic resummation of the logarithmically enhanced into factorized lepton distribution and fragmentation (or jet) functions that are universal for all final states. The new approach provides a uniform treatment of RCs for the extraction of parton distribution functions, transverse momentum dependent distributions, and other partonic correlation functions from lepton-hadron collision data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Soft and hard aspects of QCD dynamics in hadronic form factors

I give an overview of (mostly my own) work on aspects of QCD dynamics in hadronic form factors at large momentum transfer. The topics include a discussion of basics of soft and hard mechanisms, QCD sum rule applications, and connection of form factors to generalized parton distributions.

Radyushkin, Anatoly↗
DOE OSTI2024

A Review and Revalidation of Equivalency Factors in H-Canyon

In recent years, an effort has begun to validate and reaffirm long-existing limits and equivalency factors in use at the H-Canyon (HCA) facility located at the Savanah River Site. Equivalency factors (EF) are coefficients used to express the reactivity of a quantity of a given isotope in terms of an equivalent amount of another isotope’s reactivity, commonly termed Fissile Gram Equivalent (FGE). For criticality safety purposes, EFs are often used to conservatively determine if a given mixed-isotope system is within previously established limits. These EFs are calculated by taking ratios of established subcritical limits for a given system or process.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2026

Measuring the Stress Factors for Photovoltaic (PV) Backsheet Degradation

Back sheet failure has resulted in power loss and large-scale recall of photovoltaic modules, resulting in billions of dollars in lost revenue. The light exposure on the backside of a photovoltaic module comes primarily from reflected light which alters the distribution of natural sunlight. Because of this, modelling the backside exposure and duplicating the exposure is much more difficult than modeling the frontside exposure. This project aims to study how various back sheets and junction box materials degrade under different conditions and to develop Python code to help model and predict degradation. The stress factors for back-sheet degradation must be quantified to extrapolate accelerated stress tests to the field. Test samples were placed in the A3, A4, and A5 conditions, as defined in IEC 62788-7-2, to assess the temperature and humidity dependence of ultraviolet (UV) induced degradation. We are utilizing a custom chamber with exposure from 0.5 UV-suns to 5 UV-suns to understand the dependence of degradation on light intensity. A group of samples put in the A3 condition had glass filters with 50% UV cut-offs of 320 nm, 335 nm, and 360 nm to assess the wavelength dependence of UV degradation. All this data is necessary to assess the impact of non-standard UV light exposure. The material evaluation tests include gloss measurements, attenuated total internal reflectance Fourier transform infrared spectroscopy (ATR-FTIR), UV-visible reflectance/transmittance utilizing a Cary Ci7000 spectrophotometer, and a nano-indenter for surface hardness and modulus measurements. Alongside the experimental work, there is a computational effort using raytracing and Python open-source tools in PVDeg , PVLib, and Bifacial_Radiance. This code will create specific exposure scenarios and enable the evaluation of chamber degradation relative to field degradation. Equation 1 is a strawman equation used to model degradation on the backside of a PV module. We will create simplified code, based on the results of ray-tracing calculations, which uses a view factor approach to provide fast calculations for the most common exposure scenarios.

14 SOLAR ENERGY↗
DOE OSTI2021

Targeting Drugs Against Fibroblast Growth Factor(s)-Induced Cell Signaling

Background:: The fibroblast growth factor (FGF) family is comprised of 23 highly regulatedmonomeric proteins that regulate a plethora of developmental and pathophysiological processes,including tissue repair, wound healing, angiogenesis, and embryonic development. Binding ofFGF to fibroblast growth factor receptor (FGFR), a tyrosine kinase receptor, is facilitated by a glycosaminoglycan,heparin. Activated FGFRs phosphorylate the tyrosine kinase residues that mediateinduction of downstream signaling pathways, such as RAS-MAPK, PI3K-AKT, PLCγ, andSTAT. Dysregulation of the FGF/FGFR signaling occurs frequently in cancer due to gene amplification,FGF activating mutations, chromosomal rearrangements, integration, and oncogenic fusions.Aberrant FGFR signaling also affects organogenesis, embryonic development, tissue homeostasis,and has been associated with cell proliferation, angiogenesis, cancer, and other pathophysiologicalchanges. Objective:: This comprehensive review will discuss the biology, chemistry, and functions of FGFs,and its current applications toward wound healing, diabetes, repair and regeneration of tissues, andfatty liver diseases. In addition, specific aberrations in FGFR signaling and drugs that target FGFRand aid in mitigating various disorders, such as cancer, are also discussed in detail. Conclusion:: Inhibitors of FGFR signaling are promising drugs in the treatment of several types ofcancers. The clinical benefits of FGF/FGFR targeting therapies are impeded due to the activationof other RTK signaling mechanisms or due to the mutations that abolish the drug inhibitory activityon FGFR. Thus, the development of drugs with a different mechanism of action for FGF/FGFRtargeting therapies is the recent focus of several preclinical and clinical studies.

Pharmacology & Pharmacy↗
DOE OSTI2022

Connecting Matrix Elements to Multi-Hadron Form-Factors

We discuss developments in calculating multi-hadron form-factors and transition processes via lattice QCD. Our primary tools are finite-volume scaling relations, which map spectra and matrix elements to the corresponding multi-hadron infinite-volume amplitudes. We focus on two hadron processes probed by an external current, and provide various checks on the finite-volume formalism in the limiting cases of perturbative interactions and systems forming a bound state. By studying model-independent properties of the infinite-volume amplitudes, we are able to rigorously define form-factors of resonances.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Nucleon form factors and the pion-nucleon sigma term

This talk summarizes the progress made since Lattice 2021 in understanding and controlling the contributions of towers of multihadron excited states with mass gaps starting lower than of radial excitations, and in increasing our confidence in the extraction of ground state nucleon matrix elements. The most clear evidence for multihadron excited state contributions (ESC) is in axial/pseudoscalar form factors that are required to satisfy the PCAC relation between them. The talk examines the broader question--which and how many of the theoretically allowed positive parity states N(p)π(−p), N(0)π(0)π(0), N(p)π(0), N(0)π(p), … make significant contributions to a given matrix element? New data for the axial, electric and magnetic form factors are presented. They continue to show trends observed in Ref.[1]. The N2LO χPT analysis of the ESC to the pion-nucleon sigma term, σπN, has been extended to include the Δ as an explicit degree of freedom [2]. The conclusion reached in Ref.[3] that Nπ and Nππ states each contribute about 10 MeV to σπN, and the consistency between the lattice result with Nπ state included and the phenomenological estimate is not changed with this improvement.

Gupta, Rajan↗
DOE OSTI2025

Gravitational form factors of glueballs in Yang-Mills theory

This work presents preliminary results of the first determination of the energy-momentum tensor form factors of the scalar glueball, referred to as gravitational form factors (GFFs). The calculation has been carried out in lattice Yang-Mills theory at a single lattice spacing. Using variationally optimized operators, the matrix elements are extracted from ratios of three-point functions to two-point functions. The glueball GFFs and their kinematic dependence are compared to those of other hadrons from previous calculations.

Abbott, Ryan [Massachusetts Institute of Technolog↗