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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

The HalfDome multi-survey cosmological simulations: N-body simulations

Upcoming cosmological surveys have the potential to reach groundbreaking discoveries on multiple fronts, including the neutrino mass, dark energy, and inflation. Most of the key science goals require the joint analysis of datasets from multiple surveys to break parameter degeneracies and calibrate systematics. To realize such analyses, a large set of mock simulations that realistically model correlated observables is required. In this paper we present the N-body component of the HalfDome cosmological simulations, designed for the joint analysis of Stage-IV cosmological surveys, such as Rubin LSST, Euclid, SPHEREx, Roman, DESI, PFS, Simons Observatory, CMB-S4, and LiteBIRD. Our 300TB initial data release includes full-sky lightcones and halo catalogs between z = 0–4 for 11 fixed cosmology realizations, as well as an additional run with local primordial non-Gaussianity (f NL = 20). The simulations evolve 61443 particles in a 3.75 h -1 Gpc box, reaching a minimum halo mass of ∼6 × 1012 h -1 M ⊙ and maximum scale of k ∼ h Mpc-1. Our data is publicly available: instructions to access the data and plans for future data releases can be found at https://halfdomesims.github.io.

Bayer, Adrian E↗
DOE OSTI2025

Hanford Composite Analysis Special Studies FY2025 - Groundwater Flow Simulation for use in a Comparison of Simulated Concentrations in the Saturated Zone Estimated by the Plateau-to-River Model Versions 8.3 and 9.1

In order to meet the requirements of U.S. Department of Energy (DOE) in DOE O 435.1, Radioactive Waste Management, a composite analysis (CA) must be completed for the Central Plateau at the Hanford Site. The CA requires estimates of fate and transport of radionuclides in the groundwater from multiple sources within the modeling domain. This Environmental Calculation File (ECF) details the application of the Plateau-to-River (P2R) Model (CP-57037, Rev. 3, Model Package Report for the P2R Model: Version 9.1) to predict the flow of groundwater on the Central Plateau for the 10,000-year simulation to support a special analysis associated with the Hanford Site CA. The simulated flow field will support the simulation of fate and transport of contaminants for comparison to the results obtained as part of the CA to evaluate impact of the updated version of the P2R Model.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

ILAMBv2.7 benchmarking results comparing E3SMv2.1 land-atmosphere coupled (BGCv2LNDATM) and stand alone land (ELM) simulations with CMIP6 emission driven historical simulations

This dataset contains land model benchmarking results for the Energy Exascale Earth System Model version 2.1 (E3SMv2.1), including outputs from both coupled biogeochemistry simulations and stand-alone land model simulations. These results are compared against several emission-driven historical simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6). Benchmarking was conducted using the International Land Model Benchmarking (ILAMB) package, version 2.7 (ILAMBv2.7). CMIP6 model outputs were sourced from the Earth System Grid Federation (ESGF), while the E3SMv2.1 results were derived from raw model outputs. These outputs underwent processing steps such as time serialization, conservative regridding, and data standardization to ensure comparability. For spatial interpolation, the Earth System Modeling Framework (ESMF) tool, ESMF_RegridWeightGen, was employed to generate regridding weights, enabling the transformation of E3SM’s native cubed-sphere grid to a regular latitude-longitude grid.

Feng, Sha [PNNL]↗
DOE OSTI2025

The AGORA High-resolution Galaxy Simulations Comparison Project. VIII. Disk Formation and Evolution of Simulated Milky Way Mass Galaxy Progenitors at 1 < z < 5

We investigate how differences in the stellar feedback produce disks with different morphologies in Milky Way–like progenitors over 1 ≤ z ≤ 5, using eight state-of-the-art cosmological hydrodynamics simulation codes in the AGORA project. In three of the participating codes, a distinct, rotation-dominated inner core emerges with a formation timescale of ≲300 Myr, largely driven by a major merger event, while two other codes exhibit similar signs of wet compaction—gaseous shrinkage into a compact starburst phase—at earlier epochs. The remaining three codes show only weak evidence of wet compaction. Consequently, we divide the simulated galaxies into two groups: those with strong compaction signatures and those with weaker ones. Galaxies in these two groups differ in size, stellar age gradients, and disk-to-total mass ratios. Specifically, codes with strong wet compaction build their outer disks in an inside-out fashion, leading to negative age gradients, whereas codes with weaker compaction feature flat or positive age gradients caused primarily by outward stellar migration. Although the stellar half-mass radii of these two groups diverge at z ∼ 3, the inclusion of dust extinction brings their sizes and shapes in mock observations closer to each other and to observed galaxies. We attribute the observed morphological differences primarily to variations in the stellar feedback implementations—such as delayed cooling timescales, and feedback strengths—that regulate both the onset and duration of compaction. Overall, our results suggest that disk assembly at high redshifts is highly sensitive to the details of the stellar feedback prescriptions in simulations.

Jung, Minyong [Seoul National Univ. (Korea, Republ↗
NASA NTRS1974

Ground testing and simulation. II - Aerodynamic testing and simulation: Saving lives, time, and money

The present work discusses in general terms the various kinds of ground facilities, in particular, wind tunnels, which support aerodynamic testing. Since not all flight parameters can be simulated simultaneously, an important problem consists in matching parameters. It is pointed out that there is a lack of wind tunnels for a complete Reynolds-number simulation. Using a computer to simulate flow fields can result in considerable reduction of wind-tunnel hours required to develop a given flight vehicle.

Dayman, B., Jr.↗
NASA NTRS1974

Simulation verification techniques study: Simulation self test hardware design and techniques report

The final results are presented of the hardware verification task. The basic objectives of the various subtasks are reviewed along with the ground rules under which the overall task was conducted and which impacted the approach taken in deriving techniques for hardware self test. The results of the first subtask and the definition of simulation hardware are presented. The hardware definition is based primarily on a brief review of the simulator configurations anticipated for the shuttle training program. The results of the survey of current self test techniques are presented. The data sources that were considered in the search for current techniques are reviewed, and results of the survey are presented in terms of the specific types of tests that are of interest for training simulator applications. Specifically, these types of tests are readiness tests, fault isolation tests and incipient fault detection techniques. The most applicable techniques were structured into software flows that are then referenced in discussions of techniques for specific subsystems.

Source record↗
NASA NTRS1977

Simulation of a synergistic six-post motion system on the flight simulator for advanced aircraft at NASA-Ames

Motion system drive philosophy and corresponding real-time software have been developed for the purpose of simulating the characteristics of a typical synergistic Six-Post Motion System (SPMS) on the Flight Simulator for Advanced Aircraft (FSAA) at NASA-Ames which is a non-synergistic motion system. This paper gives a brief description of these two types of motion systems and the general methods of producing motion cues of the FSAA. An actuator extension transformation which allows the simulation of a typical SPMS by appropriate drive washout and variable position limiting is described.

Bose, S. C.↗
NASA NTRS1978

Feasibility and concept study to convert the NASA/AMES vertical motion simulator to a helicopter simulator

The conceptual design for converting the vertical motion simulator (VMS) to a multi-purpose aircraft and helicopter simulator is presented. A unique, high performance four degrees of freedom (DOF) motion system was developed to permanently replace the present six DOF synergistic system. The new four DOF system has the following outstanding features: (1) will integrate with the two large VMS translational modes and their associated subsystems; (2) can be converted from helicopter to fixed-wing aircraft simulation through software changes only; (3) interfaces with an advanced cab/visual display system of large dimensions; (4) makes maximum use of proven techniques, convenient materials and off-the-shelf components; (5) will operate within the existing building envelope without modifications; (6) can be built within the specified weight limit and avoid compromising VMS performance; (7) provides maximum performance with a minimum of power consumption; (8) simple design minimizes coupling between motions and maximizes reliability; and (9) can be built within existing budgetary figures.

Belsterling, C. A.↗
NASA NTRS1980

Scale effects: HCMM data simulation. Usage of filtering techniques for scaling-up simulations

Image reduction used to simulate increase in altitude of an acquisition platform is equivalent to data smoothing, and can be achieved either by neighborhood averaging or by filtering techniques. The averaging approach is limited for accurate simulation. A filtering method is described which was based on the hypothesis that all changes due to altitude increase can be represented by a point spread function. Determination of the scale function and factor are discussed as well as implementation of the filtering. Filtering can be either in the spatial or frequency domain. In the spatial domain, filtering consists of the convolution of the image with the weights mask, and then of the declination of the points according to the appropriates scale factor. A simulation of an aircraft day image in the infrared channel is examined.

Digennaro, V.↗
NASA NTRS1984

TAC BRAWLER - An application of engagement simulation modeling to simulator visual system display requirements for air combat maneuvering

The TAC BRAWLER air combat simulation models both the acquisition and use of visual information by the pilot. It was used to provide the designers of manned simulators for air-to-air combat with information regarding the training implications of display system resolution, inherent target contrast, field of view, and transport delay. Various display designs were simulated, and the resulting quantitative and qualitative differences in engagements were considered indicators of possible mistraining. Display resolution was found to alter combats primarily through its effect on detection ranges; the 'pixel averaging' contrast management technique was shown to largely compensate for this problem. Transport delay significantly degrades pilot tracking ability, but the training impact of the effect is unclear.

Kerchner, R. M.↗
NASA NTRS1985

Space plasma simulations; Proceedings of the Second International School for Space Simulations, Kapaa, HI, February 4-15, 1985. Parts 1 & 2

Space plasma simulations, observations, and theories are discussed. Papers are presented on the capabilities of various types of simulation codes and simulation models. Consideration is given to plasma waves in the earth's magnetotail, outer planet magnetosphere, geospace, and the auroral and polar cap regions. Topics discussed include space plasma turbulent dissipation, the kinetics of plasma waves, wave-particle interactions, whistler mode propagation, global energy regulation, and auroral arc formation.

Ashour-Abdalla, M.↗
NASA NTRS1985

Air mass 1.5 global and direct solar simulation and secondary reference cell calibration using a filtered large area pulsed solar simulator

Spectral mismatch between a solar simulator and a desired spectrum can result in nearly 20 percent measurement error in the output of photovoltaic devices. This occurs when a crystalline silicon cell monitors the intensity of an unfiltered large area pulsed solar simulator (LAPSS) simulating the ASTM air mass 1.5 direct spectrum and the test device is amorphous silicon. The LAPSS spectral irradiance is modified with readily available glass UV filters to closely match either the ASTM air mass 1.5 direct or global spectrum. Measurement error is reduced to about 1 percent when using either filter if the reference cell and test device are the same general type.

Mueller, Robert L.↗
NASA NTRS1987

A simulation of the IPS variations from a magnetohydrodynamical simulation

Calculations of the variations of interplanetary scintillation (IPS) from a disturbance simulated by a 3-D magnetohydrodynamical (MHD) model of the solar wind are presented. The simulated maps are compared with observations and it is found that the MHD model reproduces the qualitative features of observed disturbances. The disturbance produced by the MHD simulation is found to correspond in strength with the weakest disturbance which can be reliably detected by existing single station IPS observations.

Tappin, S. J.↗
NASA NTRS1988

The two axis motion simulator for the large space simulator at ESTEC (European Space Research and Technology Center)

The Large Space Simulator at the European Space Research and Technology Center (ESTEC) has been recently equipped with a motion simulator capable of handling test items of 5 tons mass and having a volume of 7m in diameter and a length of 7m. The motion simulator has a modular set-up. It consists of a spinbox as a basic unit on which the test article is mounted and which allows continuous rotation (spin) . This spinbox can be used in two operational configurations; the spin axis is vertical to 30 degrees when mounted on a gimbalstand; and the spin axis is horizontal when mounted on a turntable-yoke combination. The turntable provides rotation within plus or minus 90 degrees. This configuration allows one to bring a test article to all possible relative positions viv-a-vis the sun vector (which is horizontal in this case). The spinbox allows fast rotation between 1 to 6 rpm or slow rotation between 1 to 25 rotations per day as well as positioning within plus or minus 0.4 degrees accuracy.

Beckel, Kurt A.↗
NASA NTRS1989

Satellite range delay simulator for a matrix-switched time division multiple-access network simulator

The Systems Integration, Test, and Evaluation (SITE) facility at NASA Lewis Research Center is presently configured as a satellite-switched time division multiple access (SS-TDMA) network simulator. The purpose of SITE is to demonstrate and evaluate advanced communication satellite technologies, presently embodied by POC components developed under NASA contracts in addition to other hardware, such as ground terminals, designed and built in-house at NASA Lewis. Each ground terminal in a satellite communications system will experience a different aspect of the satellite's motion due mainly to daily tidal effects and station keeping, hence a different duration and rate of variation in the range delay. As a result of this and other effects such as local oscillator instability, each ground terminal must constantly adjust its transmit burst timing so that data bursts from separate ground terminals arrive at the satellite in their assigned time slots, preventing overlap and keeping the system in synchronism. On the receiving end, ground terminals must synchronize their local clocks using reference transmissions received through the satellite link. A feature of the SITE facility is its capability to simulate the varying propagation delays and associated Doppler frequency shifts that the ground terminals in the network have to cope with. Delay is achieved by means of two NASA Lewis designed and built range delay simulator (RDS) systems, each independently controlled locally with front panel switches or remotely by an experiment control and monitor (EC/M) computer.

Nagy, Lawrence A.↗
NASA NTRS1990

Satellite range delay simulator for a matrix-switched time division multiple-access network simulation system

The Systems Integration, Test, and Evaluation (SITE) facility at NASA Lewis Research Center is presently configured as a satellite-switched time division multiple access (SS-TDMA) network simulator. The purpose of SITE is to demonstrate and evaluate advanced communication satellite technologies, presently embodied by POC components developed under NASA contracts in addition to other hardware, such as ground terminals, designed and built in-house at NASA Lewis. Each ground terminal in a satellite communications system will experience a different aspect of the satellite's motion due mainly to daily tidal effects and station keeping, hence a different duration and rate of variation in the range delay. As a result of this and other effects such as local oscillator instability, each ground terminal must constantly adjust its transmit burst timing so that data bursts from separate ground terminals arrive at the satellite in their assigned time slots, preventing overlap and keeping the system in synchronism. On the receiving end, ground terminals must synchronize their local clocks using reference transmissions received through the satellite link. A feature of the SITE facility is its capability to simulate the varying propagation delays and associated Doppler frequency shifts that the ground terminals in the network have to cope with. Delay is ahcieved by means of two NASA Lewis designed and built range delay simulator (RDS) systems, each independently controlled locally with front panel switches or remotely by an experiment control and monitor (EC/M) computer.

Nagy, Lawrence A.↗
NASA NTRS1990

Large eddy simulations and direct numerical simulations of high speed turbulent reacting flows

This research is involved with the implementation of advanced computational schemes based on large eddy simulations (LES) and direct numerical simulations (DNS) to study the phenomenon of mixing and its coupling with chemical reactions in compressible turbulent flows. In the efforts related to LES, a research program to extend the present capabilities of this method was initiated for the treatment of chemically reacting flows. In the DNS efforts, the focus is on detailed investigations of the effects of compressibility, heat release, and non-equilibrium kinetics modelings in high speed reacting flows. Emphasis was on the simulations of simple flows, namely homogeneous compressible flows, and temporally developing high speed mixing layers.

Givi, Peyman↗