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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 289 records · Page 16

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NASA NTRS1984

Heat generation in aircraft tires under braked rolling conditions

An analytical model was developed to approximate the internal temperature distribution in an aircraft tire operating under conditions of unyawed braked rolling. The model employs an array of elements to represent the tire cross section and considers the heat generated within the tire to be caused by the change in strain energy associated with cyclic tire deflection. The additional heating due to tire slip and stresses induced by braking are superimposed on the previously developed free rolling model. An extensive experimental program was conducted to verify temperatures predicted from the analytical model. Data from these tests were compared with calculations over a range of operating conditions. The model results were in reasonably good agreement with measured values.

Clark, S. K.↗

NASA NTRS1984

High-resolution, far-ultraviolet study of Beta Draconis (G2 Ib-II) - Transition region structure and energy balance

High-resolution far ultraviolet spectra of the star Beta Draconis have been obtained with the IUE satellite. The observations and emission line data from the spectra are presented, the interpretation of the emission line widths and shifts is discussed, and the implications are given in terms of atmospheric properties. The emission measure distribution is derived, and density diagnostics involving both line ratios and line opacity arguments is investigated. The methods for calculating spherically symmetric models of the atmospheric structure are outlined, and several such models are presented. The extension of these models to log T(e) greater than 5.3 using the observed X-ray flux is addressed, the energy balance of an 'optimum' model is investigated, and possible models of energy transport and deposition are discussed.

Brown, A.↗

NASA NTRS1987

Positron annihilation gamma rays from novae

The potential for observing annihilation gamma rays from novae is investigated. These gamma rays, a unique signature of the thermonuclear runaway models of novae, would result from the annihilation of positrons emitted by beta(+)-unstable nuclei produced near the peak of the runaway and carried by rapid convection to the surface of the nova envelope. Simple models, which are extensions of detailed published models, of the expansion of the nova atmospheres are evolved. These models serve as input into investigations of the fate of nearby Galactic fast novae could yield detectable fluxes of electron-positron annihilation gamma rays produced by the decay of N-13 and F-18. Although nuclear gamma-ray lines are produced by other nuclei, it is unlikely that the fluxes at typical nova distances would be detectable to present and near-future instruments.

Leising, Mark D.↗

NASA NTRS1991

Representing functions/procedures and processes/structures for analysis of effects of failures on functions and operations

Current qualitative device and process models represent only the structure and behavior of physical systems. However, systems in the real world include goal-oriented activities that generally cannot be easily represented using current modeling techniques. An extension of a qualitative modeling system, known as functional modeling, which captures goal-oriented activities explicitly is proposed and how they may be used to support intelligent automation and fault management is shown.

Malin, Jane T.↗

NASA NTRS2007

Eastern U.S. Continental Shelf Carbon Budget: Integrating Models,Data Assimilation, and Analysis

The U.S. East Coast Continental Shelf (USECoS) project was initiated in 2004 with the overall goal of developing carbon budgets for Mid-Atlantic and South Atlantic regions of the eastern U.S. coast. We addressed this goal through a series of specific research questions that were designed to understand carbon inputs and fates in the two regions, dominant food web pathways for carbon cycling, and similarities/differences in carbon cycling in the two continental shelf systems. The USECoS project represents a major effort to simultaneously synthesize and integrate diverse data sets, field measurements, models, and modeling approaches. We expect that the type of approach taken here will result in more insight than would be possible if each component of the program moved forward independently. The primary significance of this project is in providing a strong quantitative basis for the development of future observational and modeling studies of carbon budgets of continental shelf systems. A strong aspect of the USECoS project is the integration of modeling and extensive physical, chemical, and biological data sets, which provides an opportunity for modeling and data analyses to inform one another from the outset. This research is particularly germane to NASA's carbon cycle research focus and coastal research initiative and the U.S. Climate Change Research Program, all of which support the goals of the North American Carbon Program. We highlight primary approaches that have been used, and some of the challenges and results that have come from interactions among our team of investigators. The global scale and interdisciplinary nature of the science questions that we now face in Earth Science are such that integrated teams of investigators are needed to address them.

Hofmann, Eileen↗

NASA NTRS2011

Incorporating JULES into NASA's Land Information System (LIS) and Investigations of Land-Atmosphere Coupling

NASA's Land Information System (LIS; lis.gsfc.nasa.gov) is a flexible land surface modeling and data assimilation framework developed over the past decade with the goal of integrating satellite- and ground-based observational data products and advanced land surface modeling techniques to produce optimal fields of land surface states and fluxes. LIS features a high performance and flexible design, and operates on an ensemble of land surface models for extension over user-specified regional or global domains. The extensible interfaces of LIS allow the incorporation of new domains, land surface models (LSMs), land surface parameters, meteorological inputs, data assimilation and optimization algorithms. In addition, LIS has also been demonstrated for parameter estimation and uncertainty estimation, and has been coupled to the Weather Research and Forecasting (WRF) mesoscale model. A visiting fellowship is currently underway to implement JULES into LIS and to undertake some fundamental science on the feedbacks between the land surface and the atmosphere. An overview of the LIS system, features, and sample results will be presented in an effort to engage the community in the potential advantages of LIS-JULES for a range of applications. Ongoing efforts to develop a framework for diagnosing land-atmosphere coupling will also be presented using the suite of LSM and PBL schemes available in LIS and WRF along with observations from the U. S .. Southern Great Plains. This methodology provides a potential pathway to study factors controlling local land-atmosphere coupling (LoCo) using the LIS-WRF system, which will serve as a testbed for future experiments to evaluate coupling diagnostics within the community.

Santanello, Joseph↗

NASA NTRS2021

Simulation of Solar-Induced Chlorophyll Fluorescence from 3D Canopies with the Dart Model

The potential of solar-induced chlorophyll fluorescence (SIF) to monitor photosynthesis and plant stress has attracted considerable interest in SIF remote sensing (RS). However, canopy SIF and RS observations are impacted by topography, vegetation three dimension (3D) structure, leaf orientation, non foliar elements (e.g., tree woody skeleton), ... Physically based downscaling of canopy SIF RS data to leaf-level (i.e., to leaf photosynthesis) requires 3D radiative transfer (RT) models simulating canopy SIF and its observation. These models are necessary to better exploit the potential of SIF, by linking leaf SIF and SIF in RS observations as a function of canopy 3D architecture and experimental configurations (sun and viewing directions, etc.). The Discrete Anisotropic Radiative Transfer (DART) model is a comprehensive 3D radiative transfer (RT) model for urban and natural landscapes. This paper presents its SIF modeling for vegetation simulated with facets, its validation with the SCOPE/mSCOPE 1D models, and its recent extension to SIF modelling for landscapes simulated with 3D turbid medium.

radiative transfer↗

NASA NTRS2021

Simulation of Solar-Induced Chlorophyll Fluorescence from 3D Canopies with the Dart Model

Radiative transfer↗

NASA NTRSDate not supplied

Developing a Finite Element Soyuz Seat Environment and Investigating Occupant Injury Metrics for Accelerative Loading Across Spaceflight Vehicle Designs

Landings in the Soyuz vehicle have generated more injuries than models have predicted, and the reason for this remains unknown. Presently, 3 new capsule-type spacecraft—the Orion, the SpaceX Dragon2, and the Boeing CST-100—are in various stages of development. To better understand the injury risk to Soyuz crewmembers, and to mitigate risk of future injuries onboard the new vehicles, we conducted a finite element (FE) modeling effort. At the outset of this study, previously developed FE models were available for the seats in the 3 new vehicles, whereas the Soyuz environment had not been modeled in an extensible manner. Thus, a model of the Soyuz seat was necessary to facilitate comparisons of all seat types.

D. A. Jones↗

NASA NTRSDate not supplied

Thermal Effects of Pressure Surge and Adiabatic Compression in the Priming of Propulsion and Propellant Transfer Systems

Surge pressures and adiabatic compression during priming of evacuated lines in propulsion and propellant transfer systems has been considered. Test data were obtained for desaturated and saturated water for surge pressures and adiabatic compression for various supply pressures and temperatures. Scaling of surge pressures a t different temperatures has been carried out with the aid of Joukowsky model. The thermal effects associated with surge pressure and the attendant adiabatic compression have been investigated with the a id of a simplified analytical model, which represents an extension of the model developed by Lecourt and Steelant. It has been shown that the predictions from the model compare satisfactorily with test data for a water/helium system, and existing test data for different liquid/gas combinations.

Pressure Surge↗

DOE OSTI2023

Search for Low mass Higgs Portal Scalars at the MicroBooNE Detector in the NuMI Beam

The MicroBooNE experiment exploits Liquid Argon Time Projection Chamber (LArTPC) technology to detect neutrinos from two beams at Fermilab, Chicago: on-axis Booster Neutrino Beam (BNB) and the off-axis Neutrinos at the Main Injector (NuMI) beam. While the aim of the experiment is to study the low-energy excess of electron neutrino events observed by the MiniBooNE experiment, to search for eV-scale sterile neutrinos and to characterise neutrino interactions on argon, it could also be exploited to probe Beyond Standard Model (BSM) Physics. This thesis presents a BSM search for low-mass Higgs Portal Scalars at MicroBooNE in the NuMI beam using data collected during the Run 1 and Run 3 data-taking periods with a total exposure corresponding to $7.01 \times 10^{20}$ protons on target (POT). The Higgs Portal Model is an extension to the Standard Model in which a dark-sector scalar, $S$, mixes with the Higgs boson with mixing angle $\theta$ and acquires a coupling to the Standard Model fermions via the Higgs Yukawa coupling. We search for low-mass Higgs Portal scalars, in the mass range $100-200$ MeV, at MicroBooNE via the production channel $K \rightarrow \pi + S$, where scalars are produced from kaons decaying at rest in the NuMI target and beam dump, as well as kaons decaying in flight in the decay pipe of the NuMI beam. In the MicroBooNE detector, we search for the decay channel $S \rightarrow e^+e^-$, which is the only decay channel available to the scalars in the mass range of our search. The results are expressed as limits, at the 95\% confidence level, on the scalar-Higgs mixing angle $\theta$ for scalars in the mass range $100-200$ MeV.Date of Award1 Aug 2023Original languageEnglishAwarding InstitutionThe University of ManchesterSupervisorStefan Soldner-Rembold (Supervisor) & Justin Evans (Supervisor)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

NASA NTRS1993

Features of a SINDA/FLUINT model of a liquid oxygen supply line

The modeling features used in a steady-state heat transfer problem using SINDA/FLUINT are described. The problem modeled is a 125 feet long, 3 inch diameter pipe, filled with liquid oxygen flow driven by a given pressure gradient. The pipe is fully insulated in five sections. Three sections of 1 inch thick spray-on foam and two sections of vacuum jacket. The model evaluates friction, turns losses and convection heat transfer between the fluid and the pipe wall. There is conduction through the foam insulation with temperature dependent thermal conductivity. The vacuum space is modeled with radiation and gas molecular conduction, if present, in the annular gap. Heat is transferred between the outer surface and surrounding ambient by natural convection and radiation; and, by axial conduction along the pipe and through the vacuum jacket spacers and welded seal flanges. The model makes extensive use of SINDA/FLUINT basic capabilities such as the GEN option for nodes and conductors (to generate groups of nodes or conductors), the SIV option (to generate single, temperature varying conductors), the SIM option (for multiple, temperature varying conductors) and the M HX macros for fluids (to generate strings of lumps, paths, and ties representing a diabatic duct). It calls subroutine CONTRN (returns the relative location in the G-array of a network conductor, given an actual conductor number) enabling an extensive manipulation of conductor (calculates an assignment of their values) with DO loops. Models like this illustrate to the new and even to the old SINDA/FLUINT user, features of the program that are not so obvious or known, and that are extremely handy when trying to take advantage of both, the automation of the DATA headers and make surgical modifications to specific parameters of the thermal or fluid elements in the OPERATIONS portion of the model.

Simmonds, Boris G.↗

NASA NTRS1998

The ASAC Air Carrier Investment Model (Third Generation)

To meet its objective of assisting the U.S. aviation industry with the technological challenges of the future, NASA must identify research areas that have the greatest potential for improving the operation of the air transportation system. To accomplish this, NASA is building an Aviation System Analysis Capability (ASAC). The ASAC differs from previous NASA modeling efforts in that the economic behavior of buyers and sellers in the air transportation and aviation industries is central to its conception. To link the economics of flight with the technology of flight, ASAC requires a parametrically based model with extensions that link airline operations and investments in aircraft with aircraft characteristics. This model also must provide a mechanism for incorporating air travel demand and profitability factors into the airlines' investment decisions. Finally, the model must be flexible and capable of being incorporated into a wide-ranging suite of economic and technical models flat are envisioned for ASAC.

Wingrove, Earl R., III↗

NASA NTRS1974

An experimental test of plant canopy reflectance models on cotton

Extensive data on the plant parameters necessary to evaluate any model are presented for a cotton crop. The variation of the bidirectional reflectance function with observer altitude, observer azimuth, and sun altitude angle is presented for a high density cotton crop having leaf index of 19. A comparison with the quantitative behavior obtained from the Suits model is accomplished in the wavelength region from 400 nm to 1050 nm.

Lemaster, E. W.↗

DOE OSTI2024

Subject-specific multi-scale modeling of the fate of inhaled aerosols

Determining the fate of inhaled aerosols in the respiratory system is essential in assessing the potential toxicity of inhaled airborne materials, responses to airborne pathogens, or in improving inhaled drug delivery. The availability of high-resolution clinical lung imaging and advances in the reconstruction of lung airways from CT images have led to the development of subject-specific in-silico 3D models of aerosol dosimetry, often referred to as computational fluid-particle-dynamics (CFPD) models. As CFPD models require extensive computing resources, they are typically confined to the upper and large airways. These models can be combined with lower-dimensional models to form multiscale models that predict the transport and deposition of inhaled aerosols in the entire respiratory tract. Understanding where aerosols deposit is only the first of potentially several key events necessary to predict an outcome, being a detrimental health effect or a therapeutic response. To that end, multiscale approaches that combine CFPD with physiologically-based pharmacokinetics (PBPK) models have been developed to evaluate the absorption, distribution, metabolism, and excretion (ADME) of toxic or medicinal chemicals in one or more compartments of the human body. CFPD models can also be combined with host cell dynamics (HCD) models to assess regional immune system responses. Here, this paper reviews the state of the art of these different multiscale approaches and discusses the potential role of personalized or subject-specific modeling in respiratory health.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2020

Hadronic interaction model sibyll 2.3d and extensive air showers

We present a new version of the hadron interaction event generator SIBYLL. While the core ideas of the model have been preserved, the new version handles the production of baryon pairs and leading particles in a new way. In addition, production of charmed hadrons is included. Updates to the model are informed by high-precision measurements of the total and inelastic cross sections with the forward detectors at the LHC that constrain the extrapolation to ultrahigh energy. Minimum-bias measurements of particle spectra and multiplicities support the tuning of fragmentation parameters. This paper demonstrates the impact of these changes on air-shower observables such as X max and N μ , drawing comparisons with other contemporary cosmic-ray interaction models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2022

Modeling of Cube Array Roughness: RANS, Large Eddy Simulation, and Direct Numerical Simulation

Abstract Flow over arrays of cubes is an extensively studied model problem for rough wall turbulent boundary layers. While considerable research has been performed in computationally investigating these topologies using direct numerical simulation (DNS) and large eddy simulation (LES), the ability of sublayer-resolved Reynolds-averaged Navier–Stokes (RANS) to predict the bulk flow phenomena of these systems is relatively unexplored, especially at low and high packing densities. Here, RANS simulations are conducted on six different packing densities of cubes in aligned and staggered configurations. The packing densities investigated span from what would classically be defined as isolated, up to those in the d-type roughness regime, filling in the gap in the present literature. Three different sublayer-resolved turbulence closure models were tested for each case: a low Reynolds number k–ϵ model, the Menter k–ω SST model, and a full Reynolds stress model. Comparisons of the velocity fields, secondary flow features, and drag coefficients are made between the RANS results and existing LES and DNS results. There is a significant degree of variability in the performance of the various RANS models across all comparison metrics. However, the Reynolds stress model demonstrated the best accuracy in terms of the mean velocity profile as well as drag partition across the range of packing densities.

Engineering↗

NASA NTRS2017

The Generic Resolution Advisor and Conflict Evaluator (GRACE) for Detect-And-Avoid Systems

Java Architecture for Detect-And-Avoid (DAA) Extensibility and Modeling (JADEM) was developed at NASA Ames Research Center as a research and modeling tool for Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS). UAS will be required to have DAA systems in order to fulfill the regulatory requirement to remain well clear'' of other traffic. JADEM supports research on technological requirements and Minimum Operational Performance Standards (MOPS) for UAS DAA systems by providing a flexible and extensible software platform that includes models and algorithms for all major DAA functions. This paper describes one of these algorithms, the Generic Resolution Advisor and Conflict Evaluator (GRACE). GRACE supports two core DAA functions: threat evaluation and guidance. GRACE is generic in the sense that it is designed to work with any aircraft or sensor type (both cooperative and non-cooperative), and to be used in various applications and DAA guidance concepts, thus supporting evolving MOPS requirements and research. GRACE combines flexibility, robustness, and computational efficiency. It has modest memory requirements and can handle multiple cooperative and noncooperative intruders. GRACE has been used as a core JADEM component in several real-time and fast-time experiments, including human-in-the-loop simulations and live flight tests.

detect and avoid↗