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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 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Hellmann–Feynman connection for the relative Fisher information

The (i) reciprocity relations for the relative Fisher information (RFI, hereafter) and (ii) a generalized RFI–Euler theorem are self-consistently derived from the Hellmann–Feynman theorem. These new reciprocity relations generalize the RFI–Euler theorem and constitute the basis for building up a mathematical Legendre transform structure (LTS, hereafter), akin to that of thermodynamics, that underlies the RFI scenario. This demonstrates the possibility of translating the entire mathematical structure of thermodynamics into a RFI-based theoretical framework. Virial theorems play a prominent role in this endeavor, as a Schrödinger-like equation can be associated to the RFI. Lagrange multipliers are determined invoking the RFI–LTS link and the quantum mechanical virial theorem. An appropriate ansatz allows for the inference of probability density functions (pdf’s, hereafter) and energy-eigenvalues of the above mentioned Schrödinger-like equation. The energy-eigenvalues obtained here via inference are benchmarked against established theoretical and numerical results. A principled theoretical basis to reconstruct the RFI-framework from the FIM framework is established. Numerical examples for exemplary cases are provided. - Highlights: • Legendre transform structure for the RFI is obtained with the Hellmann–Feynman theorem. • Inference of the energy-eigenvalues of the SWE-like equation for the RFI is accomplished. • Basis for reconstruction of the RFI framework from the FIM-case is established. • Substantial qualitative and quantitative distinctions with prior studies are discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Novel results for kinklike structures and their connections to quantum mechanics

In this work we use the deformation procedure and explore the route to obtain distinct field theory models that present similar stability potentials. Starting from systems that interact polynomially or hyperbolically, we use a deformation function which allows to construct other theories having the feature of giving rise to the same stability potentials. Such deformation function leads to smooth potentials according to a specific choice of a single parameter. Among the results, one shows that for models with asymmetric topological sectors, the appearance of a new stability potential is also possible.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Constraining Galaxy-Halo connection using machine learning

We investigate the potential of machine learning (ML) methods to model small-scale galaxy clustering for constraining Halo Occupation Distribution (HOD) parameters. Our analysis reveals that while many ML algorithms report good statistical fits, they often yield likelihood contours that are significantly biased in both mean values and variances relative to the true model parameters. This highlights the importance of careful data processing and algorithm selection in ML applications for galaxy clustering, as even seemingly robust methods can lead to biased results if not applied correctly. ML tools offer a promising approach to exploring the HOD parameter space with significantly reduced computational costs compared to traditional brute-force methods if their robustness is established. Using our ANN-based pipeline, we successfully recreate some standard results from recent literature. Properly restricting the HOD parameter space, transforming the training data, and carefully selecting ML algorithms are essential for achieving unbiased and robust predictions. Among the methods tested, artificial neural networks (ANNs) outperform random forests (RF) and ridge regression in predicting clustering statistics, when the HOD prior space is appropriately restricted. We demonstrate these findings using the projected two-point correlation function (w p (r p )), angular multipoles of the correlation function (ξ ℓ (r)), and the void probability function (VPF) of Luminous Red Galaxies from Dark Energy Spectroscopic Instrument mocks. Our results show that while combining w p (r p ) and VPF improves parameter constraints, adding the multipoles ξ 0 , ξ 2 , and ξ 4 to w p (r p ) does not significantly improve the constraints.

cosmology↗
DOE OSTI2018

Alternative pathway linked by hydrogen bonds connects heme-Fe of cytochrome c with subunit II-CuA of cytochrome a

Highlights: • Hydrogen bond, rather than carbon-carbon σ-bond, as the bridging element for electron transfer in proteins gained experimental evidence. • An alternative pathway linked by hydrogen bonds, is identified from heme-Fe of cytochrome c to subunit II-CuA of cytochrome a. • Such hydrogen bond-linked pathways occur in proteins and may be considered for intramolecular and intermolecular electron transfer. The bridging element for electron transfer in proteins is the hydrogen bond according to the new experimental perspective in preference to carbon-carbon σ-bond presently used. The purpose of this study is to identify an alternative pathway linked by hydrogen bonds suitable for electron transfer from heme-Fe of cytochrome c to subunit II-CuA of cytochrome a. A pathway consisting of 15 delocalized electron systems including peptide bonds, 5 polar groups of side chains of amino acid residues and 8 water molecules, linked by 27 hydrogen bonds, exists between the two metal electron centers of heme-Fe of cytochrome c, cytochrome c and of subunit II-CuA of cytochrome a. Pathways built of delocalized π-electron systems, polar groups and water molecules linked by hydrogen bonds may be considered for intramolecular and intermolecular electron transfer in proteins.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Surface chemistry connecting heterogeneous catalysis, photocatalysis and plasmonic catalysis

We report chemical reactions catalyzed by solid catalysts have recently expanded rapidly from traditional heterogeneous catalytic reactions to photocatalytic reactions and further to plasmonic-catalytic reactions, however, the fundamental understanding of the commonalities and differences among heterogeneous catalysis, photocatalysis and plasmonic catalysis is not well established. Adsorption/reactions/desorption on solid catalyst surfaces commonly occur during these catalytic processes, thus surface chemistry of solid catalysts can be taken to bridge the fundamental understanding among heterogeneous catalysis, photocatalysis and plasmonic catalysis. The purpose of this themed topic is to report novel results and review literatures’ results on surface chemistry of heterogeneous catalysis, photocatalysis and plasmonic catalysis with an attempt to summarize the commonalities and discuss the differences. Also, we believe that the themed topic will be of great interest and exert high imparts in the surface chemistry and catalysis field.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗