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At least 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Union through UNITY: Cosmology with 2000 SNe Using a Unified Bayesian Framework

Type Ia supernovae (SNe Ia) were instrumental in establishing the acceleration of the Universe’s expansion. By virtue of their combination of distance reach, precision, and prevalence, they continue to provide key cosmological constraints, complementing other cosmological probes. Individual SN surveys cover only over about a factor of 2 in redshift, so compilations of multiple SN data sets are strongly beneficial. We assemble an up-to-date “Union” compilation of 2087 cosmologically useful SNe Ia from 24 data sets (“Union3”). We take care to put all SNe on the same distance scale and update the light-curve fitting with SALT3 to use the full rest-frame optical. Over the next few years, the number of cosmologically useful SNe Ia will increase by more than a factor of 10, and keeping systematic uncertainties subdominant will be more challenging than ever. We discuss the importance of treating outliers, selection effects, light-curve shape/color populations/standardization relations, unexplained dispersion, and heterogeneous observations simultaneously. We present an updated Bayesian framework, called UNITY1.5 (Unified Nonlinear Inference for Type-Ia cosmologY), that incorporates significant improvements in our ability to model selection effects, standardization, and systematic uncertainties compared to earlier analyses. As an analysis byproduct, we also recover the posterior of the SN-only peculiar-velocity field, although we do not interpret it in this work. We compute updated cosmological constraints with Union3 and UNITY1.5, finding weak 1.7σ–2.6σ tension with flat cold dark matter and possible evidence for thawing dark energy (w0 > − 1, wa < 0). We release our SN distances, light-curve fits, and UNITY1.5 framework to the community.

Rubin, David↗
DOE OSTI2024

UPCluster-SZ: The Updated Catalog of Galaxy Clusters from the List of Planck Sunyaev–Zel’dovich Sources

Abstract We present the updated galaxy cluster catalog of the second Planck catalog of Sunyaev–Zel’dovich sources (PSZ2) through the compilation of the data for clusters and galaxies with spectroscopically measured redshifts in the literature. The original version of PSZ2 comprises 1653 Sunyaev–Zel’dovich (SZ) sources, of which 1203 have been validated as genuine galaxy clusters, while the remaining 450 sources are yet to be validated. To increase the number of genuine clusters in PSZ2, we first update the validations of the cluster candidates and their redshift information using the data compiled for the confirmed clusters and the member galaxies in the literature. We then use the galaxy redshift data in the fields of the remaining cluster candidates by searching for possible member galaxies with measured spectroscopic redshifts around the SZ centroids. In this search process, we classify clusters as strong candidates if they contain more than nine galaxies within a 4500 km s −1 velocity range and within 15′ around the SZ centroids. This process results in the validation of 139 new genuine clusters, the update of redshift information on 399 clusters, and the identification of 10 strong candidates, which increases the number of validated clusters up to 1334 among the 1653 SZ sources. Our updated galaxy cluster catalog will be very useful for studies of galaxy formation and cosmology through a combination with other all-sky surveys including the Wide-field Infrared Survey Explorer and SPHEREx.

Astronomy & Astrophysics↗
DOE OSTI2024

Implementing Ordinary Differential Equation Solvers in Rust Programming Language for Modeling Vehicle Powertrain Systems: Preprint

Efficient and accurate ordinary differential equation (ODE) solvers are necessary for powertrain and vehicle dynamics modeling. However, current commercial ODE solvers can be financially prohibitive, leading to a need for accessible, effective, open-source ODE solvers designed for powertrain modeling. Rust is a compiled programming language that has the potential to be used for fast and easy-to-use powertrain models, given its exceptional computational performance, robust package ecosystem, and short time required for modelers to become proficient. However, of the three commonly used (>3,000 downloads) packages in Rust with ODE solver capabilities, only one has more than four numerical methods implemented, and none are designed specifically for modeling physical systems. Therefore, the goal of the Differential Equation System Solver (DESS) was to implement accurate ODE solvers in Rust designed for the component-based problems often seen in powertrain modeling. DESS is a text-based software package that provides a flexible framework for building and solving systems of ODEs. This allows DESS to be included as a dependency for automotive powertrain models that require a variety of solvers and solver configurations. Seven explicit ODE solver methods have been implemented in DESS: Euler’s, Heun’s, midpoint, Ralston’s, classic Runge-Kutta, Bogacki-Shampine, and Cash-Karp. These represent five fixed-step methods and two adaptive-step methods. This paper shows that the solver implementations increase accuracy and computational efficiency compared to Euler's method when modeling a system of three thermal masses in Rust. DESS also includes features designed for modeling component-based physical systems. Users can define relationships between nodes in their system, which the package then translates into a system of equations, leading to simpler and more intuitive code. In the case of a three-thermal-mass system, the user can specify node thermal properties (e.g., thermal capacitance), how nodes are interconnected, and thermal conductance between nodes rather than providing a system of equations. The core contribution from this work is an open-source, text-based Rust package with ODE solvers for automotive powertrain modeling to support cost-free, fast, and accurate simulation.

ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2017

20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models

Measurements of the stable carbon isotope ratio ( δ 13 C) on annual tree rings offer new opportunities to evaluate mechanisms of variations in photosynthesis and stomatal conductance under changing CO 2 and climate conditions, especially in conjunction with process-based biogeochemical model simulations. The isotopic discrimination is indicative of the ratio between the CO 2 partial pressure in the intercellular cavities and the atmosphere ( c i / c a ) and of the ratio of assimilation to stomatal conductance, termed intrinsic water-use efficiency (iWUE). We performed isotope-enabled simulations over the industrial period with the land biosphere module (CLM4.5) of the Community Earth System Model and the Land Surface Processes and Exchanges (LPX-Bern) dynamic global vegetation model. Results for C3 tree species show good agreement with a global compilation of δ 13 C measurements on leaves, though modeled 13 C discrimination by C3 trees is smaller in arid regions than measured. A compilation of 76 tree-ring records, mainly from Europe, boreal Asia, and western North America, suggests on average small 20th century changes in isotopic discrimination and in c i / c a and an increase in iWUE of about 27% since 1900. LPX-Bern results match these century-scale reconstructions, supporting the idea that the physiology of stomata has evolved to optimize trade-offs between carbon gain by assimilation and water loss by transpiration. In contrast, CLM4.5 simulates an increase in discrimination and in turn a change in iWUE that is almost twice as large as that revealed by the tree-ring data. Factorial simulations show that these changes are mainly in response to rising atmospheric CO 2 . The results suggest that the downregulation of c i / c a and of photosynthesis by nitrogen limitation is possibly too strong in the standard setup of CLM4.5 or that there may be problems associated with the implementation of conductance, assimilation, and related adjustment processes on long-term environmental changes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

A new data set for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region

High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of 18.7 × 10 6 km 2 ). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to calculate SOC storage to the reference depths 0–30 cm and 0–100 cm (based on 1778 pedons). It has been shown that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100–300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m -2 ) in deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100–200 cm (524 pedons) and 200–300 cm (356 pedons) depth ranges. These pedons have been grouped into the North American and Eurasian sectors and the mean SOC storage for different soil taxa (subdivided into Gelisols including the sub-orders Histels, Turbels, Orthels, permafrost-free Histosols, and permafrost-free mineral soil orders) has been added to the updated NCSCDv2. The updated version of the data set is freely available online in different file formats and spatial resolutions that enable spatially explicit applications in GIS mapping and terrestrial ecosystem models. While this newly compiled data set adds to our knowledge of SOC in the 100–300 cm depth range, it also reveals that large uncertainties remain. In conclusion, identified data gaps include spatial coverage of deep (> 100 cm) pedons in many regions as well as the spatial extent of areas with thin soils overlying bedrock and the quantity and distribution of massive ground ice.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Dataset used to improve liquid water absorption models in the microwave

Two datasets, one a compilation of laboratory data and one a compilation from three field sites, are provided here. These datasets provide measurements of the real and imaginary refractive indices and absorption as a function of cloud temperature. These datasets were used in the development of the new liquid water absorption model that was published in Turner et al. 2015.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Critically Evaluated Energy Levels and Spectral Lines of Singly Ionized Indium (In II)

A comprehensive list of the best measured wavelengths in the In II spectrum has been compiled. Uncertainties of the wavelength measurements have been analyzed, and existing inconsistencies have been resolved. An optimized set of fine-structure energy levels that fits all observed wavelengths has been derived. Uncertainties of the energy level values have been reduced by an order of magnitude. An improved value of the ionization limit of In II has been determined by fitting quantum-defect and polarization formulas for several series of levels. Intensities of lines observed by different authors have been analyzed and converted to a uniform scale. A set of recommended values of radiative transition rates has been critically compiled, and uncertainties of these rates have been estimated. The hyperfine structure interval in the 5s 2 S ground state of In III has been determined from the measurements of the 5sng and 5snh series in In II.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1965

Space Communications: Theory and Applications. Volume 3: Information Processing and Advanced Techniques. A Bibliography, 1958 - 1963

Space Communications: Theory and Applications is a four-volume bibliography compiled by the Federal Systems Division, IBM under contract to the National Aeronautics and Space Administration. It contains an extensive listing of references to reports, articles, and books on several subjects directly pertinent to the field of space communications. The compilers have endeavored to provide maximum coverage of the literature for the period 1958 through 1963. However, references to publications of unusual significance that appeared before 1958, as well as a limited number of 1964 references, have also been included. The bibliography has been prepared primarily for use by communications specialists engaged in technical activities related to the aerospace program. Each of the four volumes is complete in its coverage of specific subjects and is being published separately.

INFORMATION PROCESSING↗
NASA NTRS1965

Ballistocardiography, a Bibliography <1877 - 1964<

The publication of this bibliography on Ballistocardiography, NASA SP-7021 (FAA AM 65-15) fulfills a long-standing requirement for a comprehensive and retrospective collection of references on a subject that is of particular interest to medical investigators and cardiovascular physiologists engaged in aerospace studies. Ballistocardiography is a technique for producing a graphical representation of repetitive motions of the human body arising from the sudden ejection of blood into the great vessels with each heart beat. Standard ballistocardiographic techniques are emphasized in the references included in the bibliography, but attention is also given to several related methods that are used to record these phenomena and to the equipment and instrumentation employed in such investigations. The format of the citations in NASA SP-7021 (FAA AM 65-15) was chosen to resemble, as closely as possible, the format that is now being used in the Index Medicwl published by the National Library of Medicine, except that English titles of foreign language articles appear in parentheses instead of in brackets as they do in Index Medicus. In each case, an attempt was made to identify the language of the article, or the place of publication of the foreign language journal. Since the citations were gathered over a period of years and occasionally from sources which do not appear in standard indexes, complete information was not always available. Citations are arranged alphabetically by personal author. In a large measure, the comprehensivenes of this collection of references is due to information obtained from card files compiled and maintained by Dr. William R. Scarborough of the Georgetown Clinical Research Institute, Office of Aviation Medicine, FAA, supplemented by the private collections of Drs. Isaac Starr, Abraham Noordergraaf, and John L. Nickerson. Selection and preparation of individual references and general editing of the material was done by Dr. Scarborough, who received valuable assistance from Mrs. Claire Tedesco of the Medical Library Branch of the FAA Library. Final compilation and printing were completed under the supervision of NASA.

AEROSPACE MEDICINE↗
NASA NTRS1972

Computer enhancement through interpretive techniques

The improvement in the usage of the digital computer through the use of the technique of interpretation rather than the compilation of higher ordered languages was investigated by studying the efficiency of coding and execution of programs written in FORTRAN, ALGOL, PL/I and COBOL. FORTRAN was selected as the high level language for examining programs which were compiled, and A Programming Language (APL) was chosen for the interpretive language. It is concluded that APL is competitive, not because it and the algorithms being executed are well written, but rather because the batch processing is less efficient than has been admitted. There is not a broad base of experience founded on trying different implementation strategies which have been targeted at open competition with traditional processing methods.

Foster, G.↗
NASA NTRS1972

Further developments in cloud statistics for computer simulations

This study is a part of NASA's continued program to provide global statistics of cloud parameters for computer simulation. The primary emphasis was on the development of the data bank of the global statistical distributions of cloud types and cloud layers and their applications in the simulation of the vertical distributions of in-cloud parameters such as liquid water content. These statistics were compiled from actual surface observations as recorded in Standard WBAN forms. Data for a total of 19 stations were obtained and reduced. These stations were selected to be representative of the 19 primary cloud climatological regions defined in previous studies of cloud statistics. Using the data compiled in this study, a limited study was conducted of the hemogeneity of cloud regions, the latitudinal dependence of cloud-type distributions, the dependence of these statistics on sample size, and other factors in the statistics which are of significance to the problem of simulation. The application of the statistics in cloud simulation was investigated. In particular, the inclusion of the new statistics in an expanded multi-step Monte Carlo simulation scheme is suggested and briefly outlined.

Chang, D. T.↗
NASA NTRS1972

Recently published protein sequences. I.

Some polypeptide sequences that have been published in the 1972 scientific literature are listed. Only selected sequences are included. The compilation has two objectives. Current information between periods when more comprehensive compilations are published is to be assembled and the use of data that do not include arrangements of unsequenced peptides for 'maximum homology' is to be encouraged.

Jukes, T. H.↗
NASA NTRS1972

FGRAAL: Technical documentation

Implementation of FGRAAL, a FORTRAN-extended graph algorithmic language for the Univac 1108 is described. The report contains the description of the implemented data structures for sets, lists and graphs. It summarizes the changes made for the RALPH compiler to accommodate the special statements of FGRAAL; gives the calling sequences generated by the changed compiler; and describes the object time subroutine package.

Mesztenyi, C. K.↗
NASA NTRS1972

Investigation using data in Alabama from ERTS-A

There are no author-identified significant results in this report. Brief summaries are presented of accomplishments by the state of Alabama in the areas of: (1) investigation of environmental factors; (2) land use compilation; (3) data processing for land use compilation; (4) photo-reproduction and unsupervised land use classification from digital tape; (5) data collection buoys; and (6) activities of the Geological Survey of Alabama.

Henry, H. R.↗
NASA NTRS1973

Application of remote sensor data to geologic analysis of the Bonanza Test Site Colorado

A geologic map of the Bonanza Test Site is nearing completion. Using published large scale geologic maps from various sources, the geology of the area is being compiled on a base scaled at 1:250,000. Sources of previously published geologic mapping include: (1) USGS Bulletins; (2) professional papers and geologic quadrangle maps; (3) Bureau of Mines reports; (4) Colorado School of Mines quarterlies; and (5) Rocky Mountain Association of Geologist Guidebooks. This compilation will be used to evaluate ERTS, Skylab, and remote sensing underflight data.

Lee, K.↗
NASA NTRS1973

The cartographic application of ERTS/RBV imagery in polar regions

The author has identified the following significant results. Experiments have demonstrated the feasibility of revising coastlines on maps of Antarctica, detected gross changes in the northern limits of the three largest ice shelves in the world, and led to the discovery of uncharted mountain ranges. A strip photomosaic compiled at a scale of 1:1,000,000 along the Victoria Land Coast between Cape Adare and Harboard Glacier shows obvious changes in size, shape, and position of such features as glaciers, ice tongues, ice shelves, and fast ice. Similar changes to features in the Thwaites Glacier Tongue area were also discovered. Comparison of existing maps and photographs with ERTS-1 imagery over portions of the Ross and Filchner-Ronne Ice Shelves reveals that their northern limits have advanced about 6 and 15 km respectively in 7 years. Imagery also revealed new and unmapped geographical features, of which some are mountains, in the area of the recently published Australian 1:1,000,000 IMW sheet SS 40-42 and USGS IMW sheet ST 57-60 which is presently in final stages of compilation. Comparison of one ERTS-1 scene with a recently published USGS map disclosed a unique change in the Erebus Glacier Tongue. Indications are that its present position is about the same as it was in 1910.

Macdonald, W. R.↗
NASA NTRS1973

Celescope catalog of ultraviolet stellar observations

The catalog contains the observational results obtained by the Celescope Experiment during the first 16 months of operation of NASA's Orbiting Astronomical Observatory (OAO-2). It lists the results of the stellar observations, along with selected ground-based information obtained from the available literature. Lunar observations (Ahmad and Deutschman, 1972), as well as other analyses of the data, are being published as separate papers. These data are available in two forms: (1) magnetic tapes and the necessary utility programs for reading and printing the contents of the tapes; and (2) this catalog, transcribed from the magnetic-tape catalog. The magnetic tape version contains not only the compiled results but also the results of the individual observations from which these averaged data were compiled.

Davis, R. J.↗