Search NASA⌕ Search

SEARCH · Search NASA

Results for “Computational methods”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Advanced Nanomaterials for Nuclear Energy and Nanotechnology

The use of the latest engineered nanomaterials in nuclear energy systems has opened doors for improving the performance and safety of nuclear power. Nuclear nanotechnology (NNT) deals with the use of engineered nanomaterials for future nuclear energy applications. In this paper, the recent progress in research and benefits of using nanomaterials in different areas of nuclear energy like nuclear fuel extraction and fabrication, fission product capturing, creating robust reactor materials, radiation sensing and monitoring, and radioactive waste separation and spent nuclear fuel reprocessing are summarized. Ongoing research around the world in this field is reviewed, including experimental and computational methods.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Activity‐Based Protein Profiling – Enabling Phenotyping of Host‐Associated and Environmental Microbiomes

Abstract Host‐associated and environmental microbiomes play central roles in human health, biogeochemical cycling, response to ecosystem change, and agriculture. Scientific approaches that can reveal the functional activities that contribute to observed phenotypes are needed in microbiome research. Broad characterization of the functional activity of microbes within microbiomes is currently hampered by approaches that rely on inference of function from metagenomes or indirect measurements. Activity‐based protein profiling is uniquely positioned to overcome these challenges and reveal the protein‐level mechanisms associated with microbiome phenotypes. In this review we describe the progress made to date using ABPP in gut microbiome, plant‐microbe interaction, and soil microbiome research, and suggest how ABPP data can be coupled with advanced computational methods to enable phenotype prediction and bioengineering of microbiomes for applied purposes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Screening for High Conductivity/Low Viscosity Ionic Liquids Using Product Descriptors

We seek to optimize Ionic liquids (ILs) for application to redox flow batteries. As part of this effort, we have developed a computational method for suggesting ILs with high conductivity and low viscosity. Since ILs consist of cation-anion pairs, we consider a method for treating ILs as pairs using product descriptors for QSPRs, a concept borrowed from the prediction of protein-protein interactions in bioinformatics. We demonstrate the method by predicting electrical conductivity, viscosity, and melting point on a dataset taken from the ILThermo database on June 18th, 2014. The dataset consists of 4,329 measurements taken from 165 ILs made up of 72 cations and 34 anions. In conclusion, we benchmark our QSPRs on the known values in the dataset then extend our predictions to screen all 2,448 possible cation-anion pairs in the dataset.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Stress field and interaction forces between dislocations and precipitate distributions

A computational method is developed for calculation of the stress field and interaction forces between dislocations and precipitates of arbitrary shape and distribution. The internal stress generated by precipitates due to coherency strain is implemented within the discrete dislocation dynamics (DDD) framework. The s-version finite element method (s-FEM), which models a precipitate of arbitrary shape using a local mesh is used to calculate coherency stress fields. The method facilitates meshing precipitate volumes of arbitrary geometry, and multiple local meshes can be superimposed at various positions of the global mesh. Accuracy and convergence conditions of the method are established. For a single precipiate, the method is shown to be 3.5 times faster than a standard FEM calculation for the same accuracy, and the gain in speed increases with the number of precipitates. The CRSS of spherical precipitates is found to be higher than disk-shaped precipitates of the same volume fraction.

42 ENGINEERING↗
DOE OSTI2023

Dissecting the structural heterogeneity of proteins by native mass spectrometry

Abstract A single gene yields many forms of proteins via combinations of posttranscriptional/posttranslational modifications. Proteins also fold into higher‐order structures and interact with other molecules. The combined molecular diversity leads to the heterogeneity of proteins that manifests as distinct phenotypes. Structural biology has generated vast amounts of data, effectively enabling accurate structural prediction by computational methods. However, structures are often obtained heterologously under homogeneous states in vitro. The lack of native heterogeneity under cellular context creates challenges in precisely connecting the structural data to phenotypes. Mass spectrometry (MS) based proteomics methods can profile proteome composition of complex biological samples. Most MS methods follow the “bottom‐up” approach, which denatures and digests proteins into short peptide fragments for ease of detection. Coupled with chemical biology approaches, higher‐order structures can be probed via incorporation of covalent labels on native proteins that are maintained at the peptide level. Alternatively, native MS follows the “top‐down” approach and directly analyzes intact proteins under nondenaturing conditions. Various tandem MS activation methods can dissect the intact proteins for in‐depth structural elucidation. Herein, we review recent native MS applications for characterizing heterogeneous samples, including proteins binding to mixtures of ligands, homo/hetero‐complexes with varying stoichiometry, intrinsically disordered proteins with dynamic conformations, glycoprotein complexes with mixed modification states, and active membrane protein complexes in near‐native membrane environments. We summarize the benefits, challenges, and ongoing developments in native MS, with the hope to demonstrate an emerging technology that complements other tools by filling the knowledge gaps in understanding the molecular heterogeneity of proteins.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

The best models of metabolism

Biochemical systems are among of the oldest application areas of mathematical modeling. Spanning a time period of over one hundred years, the repertoire of options for structuring a model and for formulating reactions has been constantly growing, and yet, it is still unclear whether or to what degree some models are better than others and how the modeler is to choose among them. In fact, the variety of options has become overwhelming and difficult to maneuver for novices and experts alike. This review outlines the metabolic model design process and discusses the numerous choices for modeling frameworks and mathematical representations. It tries to be inclusive, even though it cannot be complete, and introduces the various modeling options in a manner that is as unbiased as that is feasible. However, the review does end with personal recommendations for the choices of default models. WIREs Syst Biol Med 2017, 9:e1391. doi: 10.1002/wsbm.1391 This article is categorized under: Analytical and Computational Methods > Dynamical Methods Models of Systems Properties and Processes > Mechanistic Models Biological Mechanisms > Metabolism

Voit, Eberhard O.↗
DOE OSTI2018

Crystal Chemistry of RE 6 Mg x Cd 23- x Pb [0.6(1) ≤ x ≤ 3.2(1); RE = La and Ce]. New Mixed-Metal Derivatives of the RE 6 Cd 23 T Phases ( T = Group 14/15/16 Element)

Synthesis and crystal structure determinations are reported for six quaternary phases with the general formula RE 6 Mg x Cd 23-x Pb [RE = La, Ce; 0.6(1) ≤ x ≤ 3.2(1)]. These compounds were prepared by high temperature reaction of the elements in sealed Nb tubes. As revealed by powder and single-crystal X-ray diffraction, their crystal structures are of the cubic Zr 6 Zn 23 Si system (cF120, Fm 3 m, Z = 4), itself an interstitially filled variant of the Th 6 Mn 23 structure type. Finally, rather than distributing equally across the entire Cd 23 sub-lattice, Mg displayed a tendency to accumulate at specific sites (most notably 4a); charge differences between sites within the sub-lattice, as revealed by computational methods, are the likeliest explanation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Structure and Bonding in Heme-Nitrosyl Complexes and Implications for Biology

This review summarizes our current understanding of the geometric and electronic structures of ferrous and ferric heme–nitrosyls, which are of key importance for the biological functions and transformations of NO. In-depth correlations are made between these properties and the reactivities of these species. Here, a focus is put on the discoveries that have been made in the last 10 years, but previous findings are also included as necessary. Besides this, ferrous heme–nitroxyl complexes are also considered, which have become of increasing interest recently due to their roles as intermediates in NO and multiheme nitrite reductases, and because of the potential role of HNO as a signaling molecule in mammals. In recent years, computational methods have received more attention as a means of investigating enzyme reaction mechanisms, and some important findings from these theoretical studies are also highlighted in this chapter.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Smoky Mountain Data Challenge 2021: An Open Call to Solve Scientific Data Challenges Using Advanced Data Analytics and Edge Computing

The 2021 Smoky Mountains Computational Sciences and Engineering Conference enlists scientists from across Oak Ridge National Laboratory (ORNL) and industry to be data sponsors and help create data analytics and edge computing challenges for eminent datasets in a variety of scientific domains. This work describes the significance of each of the eight datasets and their associated challenge questions. The challenge questions for each dataset were required to cover multiple difficulty levels. An international call for participation was sent to students, asking them to form teams of up to six people and apply novel data analytics and edge computing methods to solve these challenges.

Devineni, Pravallika↗
DOE OSTI2017

Higgs-differential cross section at NNLO in dimensional regularisation

We present an analytic computation of the Higgs production cross section in the gluon fusion channel, which is differential in the components of the Higgs momentum and inclusive in the associated partonic radiation through NNLO in perturbative QCD. Our computation includes the necessary higher order terms in the dimensional regulator beyond the finite part that are required for renormalisation and collinear factorisation at N 3 LO. We outline in detail the computational methods which we employ. We present numerical predictions for realistic final state observables, specifically distributions for the decay products of the Higgs boson in the γγ decay channel.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Stable vacua with realistic phenomenology and cosmology in heterotic M-theory satisfying Swampland conjectures

We recently described a protocol for computing the potential energy in heterotic M-theory for the dilaton, complex structure and Kähler moduli. This included the leading order non-perturbative contributions to the complex structure, gaugino condensation and worldsheet instantons assuming a hidden sector that contains an anomalous U(1) structure group embedded in E8. In this paper, we elucidate, in detail, the mathematical and computational methods required to utilize this protocol. These methods are then applied to a realistic heterotic M-theory model, the B – L MSSM, whose observable sector is consistent with all particle physics requirements. Within this context, it is shown that the dilaton and universal moduli can be completely stabilized at values compatible with every phenomenological and mathematical constraint — as well as with ΛCDM cosmology. We also show that the heterotic M-theory vacua are consistent with all well-supported Swampland conjectures based on considerations of string theory and quantum gravity, and we discuss the implications of dark energy theorems for compactified theories.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Nuclear-Physical Foundation of Atomic Energy

The current status of the nuclear database used for engineering calculations in the field of nuclear energy is reported. It is shown that the nuclear database and its attendant computational methods, stabilization, and transmission to the next generation of specialists who will have to solve the problems of the future development of nuclear power must be improved and updated.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2013

From molecules to dynamic biological communities

Microbial ecology is flourishing, and in the process, is making contributions to how the ecology and biology of large organisms is understood. Ongoing advances in sequencing technology and computational methods have enabled the collection and analysis of vast amounts of molecular data from diverse biological communities. While early studies focused on cataloguing microbial biodiversity in environments ranging from simple marine ecosystems to complex soil ecologies, more recent research is concerned with community functions and their dynamics over time. Models and concepts from traditional ecology have been used to generate new insight into microbial communities, and novel system-level models developed to explain and predict microbial interactions. The process of moving from molecular inventories to functional understanding is complex and challenging, and never more so than when many thousands of dynamic interactions are the phenomena of interest. We outline the process of how epistemic transitions are made from producing catalogues of molecules to achieving functional and predictive insight, and show how those insights not only revolutionize what is known about biological systems but also about how to do biology itself. Examples will be drawn primarily from analyses of different human microbiota, which are the microbial consortia found in and on areas of the human body, and their associated microbiomes (the genes of those communities). Molecular knowledge of these microbiomes is transforming microbiological knowledge, as well as broader aspects of human biology, health and disease.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

A Combined Experimental-Computational Confirmation of the Seismic Stability of the Branched Pipelines of Systems of Nuclear Power Stations

The increase in the extent and degree of complication of the geometry of the branched pipelines of nuclear power stations has led to the appearance of natural forms of vibrations with frequencies that cannot be determined by the traditional combined experimental-computational method. This has made it necessary to develop new approaches to the experimental determination of the dynamic characteristics and to the selection of the boundaries of the design plans. Through use of the proposed correction to the technique and algorithm used in the estimation of the seismic stability of pipelines it has been possible to increase the precision with which the lowest frequencies of the natural vibrations are determined and, in certain cases, to also reduce the volume of operations through “targeted” testing performed at sites of expected maximal amplitudes of the lowest forms of vibrations.

42 ENGINEERING↗
DOE OSTI2018

FT-IR and Raman Spectroscopy and Computation of 5-Methylfurfural

5-Methylfurfural (5MF) was studied by vibrational (IR and Raman) spectroscopy and computational methods (DFT/B3LYP&MP2). FT-IR and FT-Raman spectra in KBr (at room temperature) were collected. The Gaussian 09 and Spartan 08 programs were used for conformational analysis and calculations of molecular structure, torsional barrier, and vibrational spectral data for the 5MF molecule. The obtained results were used in the analysis of experimental vibrational spectra of 5MF molecule.

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

Peptide nucleic acid Hoogsteen strand linker design for major groove recognition of DNA thymine bases

Sequence-specific targeting of double-stranded DNA and non-coding RNA via triple-helix-forming peptide nucleic acids (PNAs) has attracted considerable attention in therapeutic, diagnostic and nanotechnological fields. An E-base (3-oxo-2,3-dihydropyridazine), attached to the polyamide backbone of a PNA Hoogsteen strand by a side-chain linker molecule, is typically used in the hydrogen bond recognition of the 4-oxo group of thymine and uracil nucleic acid bases in the major groove. We report on the application of quantum chemical computational methods, in conjunction with spatial constraints derived from the experimental structure of a homopyrimidine PNA·DNA-PNA hetero-triplex, to investigate the influence of linker flexibility on binding interactions of the E-base with thymine and uracil bases in geometry-optimised model systems. Hydrogen bond formation between the N2 E-base atom and target pyrimidine base 4-oxo groups in model systems containing a β-alanine linker (J Am Chem Soc 119:11116, 1997) was found to incur significant internal strain energy and the potential disruption of intra-stand aromatic base stacking interactions in an oligomeric context. Additionally, in geometry-optimised model systems containing a 3-trans olefin linker (Bioorg Med Chem Lett 14:1551, 2004) the E-base swung out away from the target pyrimidine bases into the solvent. These findings are in qualitative agreement with calorimetric measurements in hybridisation experiments at T–A and U–A inversion sites. In contrast, calculations on a novel 2-cis olefin linker design indicate that it could permit simultaneous E-base hydrogen bonding with the thymine 4-oxo group, circumvention and solvent screening of the thymine 5-methyl group, and maintenance of triplex intra-stand base stacking interactions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Linking microstructural evolution and macro-scale friction behavior in metals [Predicting the friction behavior of metals using a microstructural evolution model]

A correlation is established between the macro-scale friction regimes of metals and a transition between two dominant atomistic mechanisms of deformation. Metals tend to exhibit bi-stable friction behavior—low and converging or high and diverging. These general trends in behavior are shown to be largely explained using a simplified model based on grain size evolution, as a function of contact stress and temperature, and are demonstrated for self-mated pure copper and gold sliding contacts. Specifically, the low-friction regime (where µ < 0.5) is linked to the formation of ultra-nanocrystalline surface films (10–20 nm), driving toward shear accommodation by grain boundary sliding. Above a critical combination of stress and temperature—demonstrated to be a material property—shear accommodation transitions to dislocation dominated plasticity and high friction, with µ > 0.5. We utilize a combination of experimental and computational methods to develop and validate the proposed structure–property relationship. As a result, this quantitative framework provides a shift from phenomenological to mechanistic and predictive fundamental understanding of friction for crystalline materials, including engineering alloys.

36 MATERIALS SCIENCE↗