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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

The Average Spectrum Norm and Near-Optimal Tensor Completion

We propose the average spectrum norm to study the minimum number of measurements required to approximate a multidimensional array (i.e., sample complexity) via low-rank tensor recovery. Our focus is on the tensor completion problem, where the aim is to estimate a multiway array using a subset of tensor entries corrupted by noise. Our average spectrum norm-based analysis provides near-optimal sample complexities, exhibiting dependence on the ambient dimensions and rank that do not suffer from exponential scaling as the order increases.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

CPGminer: An Interactive Dashboard to Explore the Genomic Features and Taxonomy of Complete Prokaryotic Genomes

Prokaryotes, the earliest forms of life on Earth, play crucial roles in global biogeochemical processes in virtually all ecosystems. The ever-increasing amount of prokaryotic genome sequencing data provides a wealth of information to examine fundamental and applied questions through systematic genome comparison. Genomic features, such as genome size and GC content, and taxonomy-centric genomic features of complete prokaryotic genomes (CPGs) are crucial for various fields of microbial research and education, yet they are often overlooked. Additionally, creating systematically curated datasets that align with research concerns is an essential yet challenging task for wet-lab researchers. In this study, we introduce CPGminer, a user-friendly tool that allows researchers to quickly and easily examine the genomic features and taxonomy of CPGs and curate genome datasets. We also provide several examples to demonstrate its practical utility in addressing descriptive questions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Analysis of five complete genome sequences for members of the class Peribacteria in the recently recognized Peregrinibacteria bacterial phylum

Five closely related populations of bacteria from the Candidate Phylum (CP) Peregrinibacteria, part of the bacterial Candidate Phyla Radiation (CPR), were sampled from filtered groundwater obtained from an aquifer adjacent to the Colorado River near the town of Rifle, CO, USA. Here, we present the first complete genome sequences for organisms from this phylum. These bacteria have small genomes and, unlike most organisms from other lineages in the CPR, have the capacity for nucleotide synthesis. They invest significantly in biosynthesis of cell wall and cell envelope components, including peptidoglycan, isoprenoids via the mevalonate pathway, and a variety of amino sugars including perosamine and rhamnose. The genomes encode an intriguing set of large extracellular proteins, some of which are very cysteine-rich and may function in attachment, possibly to other cells. Strain variation in these proteins is an important source of genotypic variety. Overall, the cell envelope features, combined with the lack of biosynthesis capacities for many required cofactors, fatty acids, and most amino acids point to a symbiotic lifestyle. Furthermore, phylogenetic analyses indicate that these bacteria likely represent a new class within the Peregrinibacteria phylum, although they ultimately may be recognized as members of a separate phylum. In conclusion, we propose the provisional taxonomic assignment as ‘ Candidatus Peribacter riflensis’, Genus Peribacter, Family Peribacteraceae, Order Peribacterales, Class Peribacteria in the phylum Peregrinibacteria.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1948

The Effect of Negative Dihedral, Tip Droop, and Wing-tip Shape on the Low-speed Aerodynamic Characteristics of a Complete Model Having a 45 Degrees Sweptback Wing

An investigation has been conducted in the Langley 300 MPH 7- by 10-foot tunnel to determine the effect of negative dihedral, tip droop, and wing-tip shape on the low-speed aerodynamic characteristics of a complete model having a 45 degrees sweptback wing. Longitudinal and lateral stability characteristics were obtained for the model with and without tail surfaces.

STABILITY, LONGITUDINAL - STATIC↗
DOE OSTI2017

Complete carbon analysis of sulfur-containing mixtures using postcolumn reaction and flame ionization detection

Quantitative analysis of complex mixtures containing hundreds-to-thousands of organic compounds rich in heteroatoms, including oxygen, sulfur, and nitrogen, is a major challenge in the fuel, food, and chemical industries. In this work, a two-stage (oxidation and methanation) catalytic process in a 3-D–printed metal microreactor was evaluated for its capability to convert sulfur-containing organic compounds to methane. The microreactor was inserted into a gas chromatograph between the capillary column and flame ionization detector. Catalytic conversion of all sulfur-containing analytes to methane enabled carbon quantification without calibration, by the method identified as “quantitative carbon detection” or QCD. Quantification of tetrahydrothiophene, dimethyl sulfoxide, diethyl sulfide, and thiophene indicated complete conversion to methane at 450°C. Long-term performance of a commercial microreactor was evaluated for 2000 consecutive injections of sulfur-containing organic analytes. The sulfur processing capacity of the microreactor was identified experimentally, after which reduced conversion to methane was observed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Toward Complete Transformation of Sodium Polysulfides by Regulating the Second-Shell Coordinating Environment of Atomically Dispersed Fe

Room temperature sodium-sulfur (RT Na-S) batteries are highly competitive as potential energy storage devices. Nevertheless, their actually achieved reversible capacities are far below the theoretical value due to incomplete transformation of polysulfides. Herein, atomically dispersed Fe-N/S active center by regulating the second-shell coordinating environment of Fe single atom is proposed. The Fe-N4S2 coordination structure with enhanced local electronic concentration around the Fermi level is revealed via synchrotron radiation X-ray absorption spectroscopy (XAS) and theoretical calculations, which can not only significantly promote the transformation kinetics of polysulfides, but induce uniform Na deposition for dendrite-free Na anode. Here as a result, the obtained S cathode delivers a high initial reversible capacity of 1590 mAh g-1, nearly the theoretical value. Here this work opens up a new avenue to facilitate the complete transformation of polysulfides for RT Na-S batteries.

25 ENERGY STORAGE↗
DOE OSTI2023

Toward Complete Transformation of Sodium Polysulfides by Regulating the Second–Shell Coordinating Environment of Atomically Dispersed Fe

Room temperature sodium-sulfur (RT Na-S) batteries are highly competitive as potential energy storage devices. Nevertheless, their actually achieved reversible capacities are far below the theoretical value due to incomplete transformation of polysulfides. Herein, atomically dispersed Fe-N/S active center by regulating the second-shell coordinating environment of Fe single atom is proposed. The Fe–N 4 S 2 coordination structure with enhanced local electronic concentration around the Fermi level is revealed via synchrotron radiation X-ray absorption spectroscopy (XAS) and theoretical calculations, which can not only significantly promote the transformation kinetics of polysulfides, but induce uniform Na deposition for dendrite-free Na anode. As a result, the obtained S cathode delivers a high initial reversible capacity of 1590 mAh g –1 , nearly the theoretical value. Finally, this work opens up a new avenue to facilitate the complete transformation of polysulfides for RT Na-S batteries.

25 ENERGY STORAGE↗
DOE OSTI2020

Electronic couplings for singlet fission: Orbital choice and extrapolation to the complete basis set limit

Abstract For the search for promising singlet fission candidates, the calculation of the effective electronic coupling, which is required to estimate the singlet fission rate between the initially excited state (S 0 S 1 ) and the multiexcitonic state ( 1 TT, two triplets on neighboring molecules, coupled into a singlet), should be sufficiently reliable and fast enough to explore the configuration space. We propose here to modify the calculation of the effective electronic coupling using a nonorthogonal configuration interaction approach by: (a) using only one set of orbitals, optimized for the triplet state of the molecules, to describe all molecular electronic states, and (b) only taking the leading configurations into consideration. Furthermore, we also studied the basis set convergence of the electronic coupling, and we found, by comparison to the complete basis set limit obtained using the cc‐pV n Z series of basis sets, that both the aug‐cc‐pVDZ and 6–311++G** basis sets are a good compromise between accuracy and computational feasibility. The proposed approach enables future work on larger clusters of molecules than dimers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Influence of the complete basis set approximation, tight weighted-core, and diffuse functions on the DLPNO-CCSD(T1) atomization energies of neutral H,C,O-compounds

The impact of complete basis set extrapolation schemes (CBS), diffuse functions, and tight weighted core functions on enthalpies of formation predicted via the DLPNO-CCSD(T1) reduced Feller Peterson-Dixon approach has been examined for neutral H,C,O-compounds. All tested three-point (TZ/QZ/5Z) extrapolation schemes result in mean unsigned deviation (MUD) below 2 kJ mol -1 relative to the experiment. Here, the two-point QZ/5Z and TZ/QZ CBS 1/$l^3_{max}$ extrapolation schemes are inferior to their inverse power counterpart (1/($l_{max}$ + 1/2) 4 ) by 1.3 and 4.3 kJ mol -1 . The CBS extrapolated frozen core atomization energies are insensitive (within 1 kJ mol -1 ) to augmentation of the basis set with tight weighted core functions. The core-valence correlation effects converge already at triple-ζ, although double- ζ/triple- ζ CBS extrapolation performs better and is recommended. The effect of diffuse function augmentation converges slowly, and cannot be reproduced with double- ζ or triple- ζ calculations as these are plagued with basis set superposition and incompleteness errors.

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

Complete Equations of State for Cyclotetramethylene Tetranitramine

Complete equations of state for the volumetric deformation of the β-polymorph of cyclotetramethylene tetranitramine (β-HMX) have been derived from its Helmholtz free energy. Dispersion-corrected density functional theory calculations were used to compute the dependence of the frequencies of the vibrational normal modes on specific volume. Here, the normal mode frequencies were used directly to generate both a tabular equation of state and an approximate model where the sum over normal mode frequencies is replaced by a set of five Debye models.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

A composite approach towards a complete model of the myosin rod

Sarcomeric myosins have the remarkable ability to form regular bipolar thick filaments that, together with actin thin filaments, constitute the fundamental contractile unit of skeletal and cardiac muscle. This has been established for over 50 years and yet a molecular model for the thick filament has not been attained. In part this is due to the lack of a detailed molecular model for the coiled–coil that constitutes the myosin rod. The ability to self–assemble resides in the C–terminal section of myosin known as light meromyosin (LMM) which exhibits strong salt–dependent aggregation that has inhibited structural studies. Here we evaluate the feasibility of generating a complete model for the myosin rod by combining overlapping structures of five sections of coiled–coil covering 164 amino acid residues which constitute 20% of LMM. Each section contains ~7–9 heptads of myosin. The problem of aggregation was overcome by incorporating the globular folding domains, Gp7 and Xrcc4 which enhance crystallization. The effect of these domains on the stability and conformation of the myosin rod was examined through biophysical studies and overlapping structures. In addition, a computational approach was developed to combine the sections into a contiguous model. The structures were aligned, trimmed to form a contiguous model, and simulated for >700 ns to remove the discontinuities and achieve an equilibrated conformation that represents the native state. As a result, this experimental and computational strategy lays the foundation for building a model for the entire myosin rod.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Complete one-loop matching for a singlet scalar in the Standard Model EFT

We present the results of the first complete one-loop matching calculation between the real singlet scalar extension of the Standard Model and the Standard Model effective field theory (SMEFT) at dimension six. Beyond their immediate relevance to the precision calculation of observables in singlet extensions of the Standard Model, our results illustrate a variety of general features of one-loop matching. We explore the interplay between non-supersymmetric non-renormalization theorems, the logarithmic dependence of Wilson coefficients, and the relevance of mixed diagrams in theories with large scale separation. In addition, we highlight some of the subtleties involved in computing observables at next-to-leading order in SMEFT by mapping our results to the T parameter at one loop.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Lattice-friendly gauge completion of a composite Higgs with top partners

We give an explicit example of a composite Higgs model with a pseudo-Nambu-Goldstone Higgs in which the top Yukawa coupling is generated via the partial compositeness mechanism. This mechanism requires composite top partners which are relatively light compared to the typical mass scale of the strongly coupled theory. While most studies of the phenomenology of such models have focused on a bottom-up approach with a minimal effective theory, a top-down approach suggests that that the theory should contain a limit in which an unbroken global chiral symmetry protects the mass of the top partners, and the spectrum of the partners satisfies `t Hooft matching conditions. We therefore consider a model for the UV gauge group which could provide a solution to the matching conditions, and note that the relatively light fermions and pseudo-Goldstone bosons fall into complete multiplets of a large approximate global symmetry. This implies that the spectrum of particles lighter than a few TeV is non-minimal. Our example illustrates likely features of a composite Higgs theory, and also serves as an example of a non-chiral theory with no sign problem and a possible solution to `t Hooft matching conditions. It would therefore be very interesting for a lattice exploration. We find in this example that for some low-energy parameters in the effective theory the top partners can decay into high multiplicity final states, which could be difficult for the Large Hadron Collider (LHC) to constrain. This may potentially allow for the top partners to be lighter than those in more minimal models.

Lattice Quantum Field Theory↗
DOE OSTI2023

Completely dark matter from rapid-turn multifield inflation

We study cosmological gravitational particle production as applied to “rapid-turn” models of inflation involving two scalar fields. We are interested in the production of massive spin-0 particles that only interact gravitationally and provide a candidate for the dark matter. Specifically, we study two models of rapid-turn multifield inflation, motivated in part by the de Sitter swampland conjecture, that are distinguished by the curvature of field space and the presence or absence of field space ‘angular momentum’ conservation. We find that one of these models leads to insufficient particle production and cannot explain the observed dark matter relic abundance. The second model is able to explain the origin of spin-0 dark matter via gravitational production, and we identify the relevant region of parameter space that is consistent with measurements of the dark-matter relic abundance, the dark-matter-photon isocurvature perturbations, and the spectrum of curvature perturbations that is probed by cosmological observations. Our work demonstrates the compatibility of the de Sitter swampland conjecture with completely dark matter.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

The complete two-loop integrated jet thrust distribution in soft-collinear effective theory

In this work, we complete the calculation of the soft part of the two-loop integrated jet thrust distribution in e+e- annihilation. This jet mass observable is based on the thrust cone jet algorithm, which involves a veto scale for out-of-jet radiation. The previously uncomputed part of our result depends in a complicated way on the jet cone size, r, and at intermediate stages of the calculation we actually encounter a new class of multiple polylogarithms. We employ an extension of the coproduct calculus to systematically exploit functional relations and represent our results concisely. In contrast to the individual contributions, the sum of all global terms can be expressed in terms of classical polylogarithms. Our explicit two-loop calculation enables us to clarify the small r picture discussed in earlier work. In particular, we show that the resummation of the logarithms of r that appear in the previously uncomputed part of the two-loop integrated jet thrust distribution is inextricably linked to the resummation of the non-global logarithms. Furthermore, we find that the logarithms of r which cannot be absorbed into the non-global logarithms in the way advocated in earlier work have coefficients fixed by the two-loop cusp anomalous dimension. We also show that in many cases one can straightforwardly predict potentially large logarithmic contributions to the integrated jet thrust distribution at L loops by making use of analogous contributions to the simpler integrated hemisphere soft function.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Charges in the UV completion of neutral electrodynamics

A theory with a non-compact form-symmetry is described by two closed form fields of degrees k and d – k. Effective theory examples are non-linear electrodynamics, a photon field coupled to a neutron field, and a low energy Goldstone boson. We show these models cannot be completed in the UV without breaking the non-compact form-symmetry down to a compact one. This amounts to the existence of electric or magnetic charges. A theory with an unbroken non-compact k-form symmetry is massless and free.

't Hooft and Polyakov loops↗
DOE OSTI2017

A complete basis of helicity operators for subleading factorization

Factorization theorems underly our ability to make predictions for many processes involving the strong interaction. Although typically formulated at leading power, the study of factorization at subleading power is of interest both for improving the precision of calculations, as well as for understanding the all orders structure of QCD. We use the SCET helicity operator formalism to construct a complete power suppressed basis of hard scattering operators for e + e - → dijets, e - p → e - jet, and constrained Drell-Yan, including the first two subleading orders in the amplitude level power expansion. We analyze the field content of the jet and soft function contributions to the power suppressed cross section for e + e - → dijet event shapes, and give results for the lowest order matching to the contributing operators. These results will be useful for studies of power corrections both in fixed order and resummed perturbation theory.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗