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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 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Time-dependent Second Order Scattering Theory for Weather Radar with a Finite Beam Width

Multiple scattering effects from spherical water particles of uniform diameter are studied for a W-band pulsed radar. The Gaussian transverse beam-profile and the rectangular pulse-duration are used for calculation. An second-order analytical solution is derived for a single layer structure, based on a time-dependent radiative transfer theory as described in the authors' companion paper. When the range resolution is fixed, increase in footprint radius leads to increase in the second order reflectivity that is defined as the ratio of the second order return to the first order one. This feature becomes more serious as the range increases. Since the spaceborne millimeter-wavelength radar has a large footprint radius that is competitive to the mean free path, the multiple scattering effect must be taken into account for analysis.

mulitple scattering↗
NASA NTRS2006

Contrasts in Sea Ice Formation and Production in the Arctic Seasonal and Perennial Ice Zones

Four years (1997-2000) of RADARSAT Geophysical Processor System (RGPS) data are used to contrast the sea ice deformation and production regionally, and in the seasonal (SIZ) and perennial (PIZ) ice zones. Ice production is of seasonal ice in openings during the winter. 3-day estimates of these quantities are provided within Lagrangian elements initially 10 km on a side. A distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the mid-winter. Regional divergence over the winter could be up to 30%. Spatially, the highest deformation is in the SIZ north of coastal Alaska. Both ice deformation and production are higher in the SIZ: deformation-related ice production in the SIZ (approx.0.5 m) is 1.5-2.3 times that of the PIZ (approx.0.3 m) - this is connected to ice strength and thickness. Atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability. Seasonal ice growth in ice fractures accounts for approx.25-40% of the total ice production of the Arctic Ocean. By itself, this deformation-ice production relationship could be considered a negative feedback when thickness is perturbed. However, the overall effect on ice production in the face of increasing seasonal and thinner/weaker ice coverage could be modified by: local destabilization of the water column promoting overturning of warmer water due to increased brine rejection; and, the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice.

Kwok, R.↗
NASA NTRS2006

Contrasts in Sea Ice Deformation and Production in the Arctic Seasonal and Perennial Ice Zones

Four years (1997-2000) of RADARSAT Geophysical Processor System (RGPS) data are used to contrast the sea ice deformation and production regionally, and in the seasonal (SIZ) and perennial (PIZ) ice zones. Ice production is of seasonal ice in openings during the winter. Three-day estimates of these quantities are provided within Lagrangian elements initially 10 km on a side. A distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the midwinter. Regional divergence over the winter could be up to 30%. Spatially, the highest deformation is seen in the SIZ north of coastal Alaska. Both ice deformation and production are higher in the SIZ: deformation-related ice production in the SIZ (approx.0.5 m) is 1.5-2.3 times that of the PIZ (approx.0.3 m): this is connected to ice strength and thickness. Atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability. Seasonal ice growth in ice fractures accounts for approx.25-40% of the total ice production of the Arctic Ocean. Uncertainties in these estimates are discussed. By itself, this deformation-ice production relationship could be considered a negative feedback when thickness is perturbed. However, the overall effect on ice production in the face of increasing seasonal and thinner/weaker ice coverage could be modified by local destabilization of the water column promoting overturning of warmer water due to increased brine rejection; and the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice. Divergence is shown to be negligibly correlated to cyclonic motion in summer and winter in both ice zones.

Arctic Ocean↗
NASA NTRS2011

Stochastic Models of Molecule Formation on Dust

We will present new theoretical models for the formation of molecules on dust. The growth of ice mantles and their layered structure is accounted for and compared directly to observations through simulation of the expected ice absorption spectra

Charnley, Steven↗
NASA NTRS2011

On Multiple-Layered Vortices

As part of an ongoing effort to find ways to make vortex flow fields decompose more quickly, photographs and observations are presented of vortex flow fields that indicate the presence of multiple layers of fluid rotating about a common axis. A survey of the literature indicates that multiple-layered vortices form in waterspouts, tornadoes and lift-generated vortices of aircraft. An explanation for the appearance of multiple-layered structures in vortices is suggested. The observations and data presented are intended to improve the understanding of the formation and persistence of vortex flow fields.

Rossow, Vernon J.↗
NASA NTRS2010

Ocular Toxicity Testing of Lunar Dust

This slide presentation reviews the use of ocular testing to determine the toxicity of lunar dust. The OECD recommendations are reviewed. With these recommendations in mind the test methodology was to use EpiOcular, tissues derived from normal human epidermal keratinocytes, the cells of which have been differentiated on cell culture inserts to form a multi-layered structure, which closely parallels the corneal epithelium and to dose the tissue with 100 mg dust from various sources. The in-vitro study provides evidence that lunar dust is not severely corrosive or irritating, however, in vitro tests have limitations, and in vivo tests provides a more complete scenario, and information, it is recommended that in vivo tests be performed.

Meyers, Valerie E.↗
NASA NTRS2012

Microstructure Formations in the Two-Phase Region of the Binary Peritectic Organic System TRIS-NPG

In order to prepare for an onboard experiment on the International Space Station (ISS), systematic directional solidification experiments with transparent hypoperitectic alloys were carried out at different solidification rates around the critical velocity for morphological stability of both solid phases. The investigations were done in the peritectic region of the binary transparent organic TRIS-NPG system where the formation of layered structures is expected to occur. The transparent appearance of the liquid and solid phase enables real time observations of the dynamic of pattern formation during solidification. The investigations show that frequently occurring nucleation events govern the peritectic solidification morphology which occurs at the limit of morphological stability. As a consequence, banded structures lead to coupled growth even if the lateral growth is much faster compared to the growth in pulling direction.

Mogeritsch, Johann↗
NASA NTRS2012

Modeling the Effects of Beam Size and Flaw Morphology on Ultrasonic Pulse/Echo Sizing of Delaminations in Carbon Composites

The size and shape of a delamination in a multi-layered structure can be estimated in various ways from an ultrasonic pulse/echo image. For example the -6dB contours of measured response provide one simple estimate of the boundary. More sophisticated approaches can be imagined where one adjusts the proposed boundary to bring measured and predicted UT images into optimal agreement. Such approaches require suitable models of the inspection process. In this paper we explore issues pertaining to model-based size estimation for delaminations in carbon fiber reinforced laminates. In particular we consider the influence on sizing when the delamination is non-planar or partially transmitting in certain regions. Two models for predicting broadband sonic time-domain responses are considered: (1) a fast "simple" model using paraxial beam expansions and Kirchhoff and phase-screen approximations; and (2) the more exact (but computationally intensive) 3D elastodynamic finite integration technique (EFIT). Model-to-model and model-to experiment comparisons are made for delaminations in uniaxial composite plates, and the simple model is then used to critique the -6dB rule for delamination sizing.

Margetan, Frank J.↗
NASA NTRS2012

MSL DAN Science Investigation: Physical Simulation of DAN

The main objective of the proposed investigation is to study the characteristics (i.e., hydrogen content, soil composition, layer-structure, etc.) of sub-surface and the surface radiation (neutron in particular) environment.

Multi-Mission Radioisotope Thermoelectric Generato↗
NASA NTRS2013

Surface Passivation by Quantum Exclusion Using Multiple Layers

A semiconductor device has a multilayer doping to provide improved passivation by quantum exclusion. The multilayer doping includes a plurality M of doped layers, where M is an integer greater than 1. The dopant sheet densities in the M doped layers need not be the same, but in principle can be selected to be the same sheet densities or to be different sheet densities. M-1 interleaved layers provided between the M doped layers are not deliberately doped (also referred to as "undoped layers"). Structures with M=2, M=3 and M=4 have been demonstrated and exhibit improved passivation.

Hoenk, Michael E.↗
NASA NTRS2014

1-Azaniumylcyclobutane-1-carboxylate monohydrate

In the title compound, C5H9NO2H2O, the amino acid is in the usual zwitterionic form involving the carboxylate group. The cyclobutane backbone of the amino acid is disordered over two conformations, with occupancies of 0.882 (7) and0.118 (7). In the crystal, NH O and OH O hydrogen bonds link the zwitterions [with the water molecule involved as both acceptor (with the NH3+) and donor (through a single carboxylate O from two different aminocyclobutane carboxylatemoities)], resulting in a two-dimensional layered structure lying parallel to (100).

Azaniumylcyclobutane↗
NASA NTRS2014

Attendee Response to Guiding Questions of the September 2014 DOE Workshop on North Slope of Alaska Priorities

We advocate for several modeling approaches suitable to prove understanding of and capability to model aerosol behavior in nucleating droplets and ice and to model regional cloud systems at the mesoscale. The full complement of data that is ideal for particular study types is increasingly well understood; the ASR ISDAC Science Plan provides an excellent example of listing the data required for each study type targeted by that campaign. Whereas discussion here focused on the microscale and mesoscale, other studies should obviously focus on the regional, seasonal and global scale. When considering ice microphysics alone, laser focus on unconstrained model components could be usefully intensified (e.g., collision-coalescence kernels). Similarly, a focus on boundary layer structure would be deeply valuable to a wide range of model types. The expense of observations motivates efficient planning for observational data sets to support specific study approaches; the concept of closure is often useful (e.g., the surface energy budget).

nucleation↗
NASA NTRS2015

Solid-State Ultracapacitor for Improved Energy Storage

NASA's Marshall Space Flight Center has developed a solid-state ultracapacitor using a novel nanocomposite, dielectric material. The material's design is based on the internal barrier layer capacitance (IBLC) concept, and it uses novel dielectric and metallic conductive ink formulations. Novel processing methods developed by NASA provide for unique dielectric properties at the grain level. Nanoscale raw material powders are tailored using a variety of techniques and then formulated into a special ink. This dielectric ink is used with novel metallic conductive ink to print a capacitor layer structure into any design necessary to meet a range of technical requirements. The innovation is intended to replace current range safety batteries that NASA uses to power the systems that destroy off-course space vehicles. A solid-state design provides the needed robustness and safety for this demanding application.

Nabors, Sammy↗
NASA NTRS2017

Nontronite and Montmorillonite as Nutrient Sources for Life on Mars

Clay minerals have been identified on Mars' oldest (Noachian) terrain and their presence suggests long-term water-rock interactions. The most commonly identified clay minerals on Mars to date are nontronite (Fe-smectite) and montmorillonite (Al-smectite) [1], both of which contain variable amounts of water both adsorbed on their surface and within their structural layers. Over Mars' history, these clay miner-al-water assemblages may have served as nutrient sources for microbial life.

Craig, P. I.↗
NASA NTRS2019

Fine-Grained, Spinel-Rich Ca-Al-Rich Inclusions From The Reduced CV3 Chondrite Efremovka: A Genetic Link To Wark-Lovering Rims?

Fine-grained, spinel-rich Ca-Al-rich inclusions (FGIs) in carbonaceous chondrites, mostly CV3 chondrites, are interpreted as aggregates of nebular gas-solid condensates that escaped significant melting [1]. Multiple lines of evidence suggest a condensation origin for FGIs, including their layered structures and irregular shapes and the fine grain size of numerous spinel-cored nodules [e.g., 2,3], and the distinctive volatility-fractionated group II rare earth element patterns of bulk inclusions and their mineral constituents [e.g., 4,5]. The origin and nature of FGIs are poorly constrained because of their fine grain sizes and intimate intergrowths of refractory phases, combined with their susceptibility to secondary parent body alteration processes, making detailed mineralogical and petrologic characterizations difficult using scanning electron microscope (SEM) and electron microprobe techniques. In this study, we present preliminary transmission electron microscope (TEM) analyses of pristine FGIs from the reduced CV3 chondrite Efremovka in order to provide the detailed characterization of their micrometer- to nanometer-scale textures and chemical compositions. Our goals are to better understand the formation processes and conditions of FGIs in the early solar nebula and to explore their possible genetic relationship with other early-formed refractory inclusions and their rims.

Keller, L. P.↗
NASA NTRS2019

X-Ray Photoelectron Spectroscopy

The interaction of photon and the electron goes back to the early part of 19th century emanating from the photo-electric effect depicted by none other than Albert Einstein (Ref 1) described in 1905, and the redistribution of kinetic energy resulting from the interaction of x-ray and solids reported during early part of the century (Ref.2). The spectrum resolutions obtained at that time was not sufficient to observe distinct peaks in spectra for materials. Thus, these phenomena hardly attracted any attention for many years following these discoveries. The modern X-ray Photoelectron Spectroscopy (XPS) has been possible by the extensive and significant contribution from Kai Siegbahn and others (Ref.3, 4) of Uppsala University. Siegbahn developed and employed a high-resolution electron spectrometer that revealed electron peaks in a spectrum emerging from the interaction of x-rays and solids. Eventually, Kai Siegbahn received Nobel Prize in 1981 for his contributions to XPS. Around 1958, shifts in elemental peaks were realized in compounds when the same elements are bound to other but different elements. This discovery resulted in the chemical state identification in various chemicals as well as the oxidation states of atoms in compounds. Because of these useful physical effects, the Uppsala group named XPS with a synonymous name of ESCA (Electron Spectroscopy for Chemical Analysis) used widely today and will be used here alternatively. Therefore, XPS or ESCA not only identifies the element, but also the compound these elements form, from their chemical shifts. Compared to other micro-analytical techniques such as Energy Dispersive (EDS) or Wavelength Dispersive (WDS) techniques, XPS analyzes only few atomic layers present on the surface. This was discovered early in 1966 (Ref. 5). While this has awarded a merit to the analytical technique to analyze very thin layers such as films and coatings, it often analyzes the adsorbed superficial gases and contaminations on a sample introduced to its analytical chamber. This necessitates the surface is cleaned and the underlying material, material of interest, is exposed in a clean environment such that the material of interest is analyzed. The cleaning is accomplished by a scanning ion gun within the analytical chamber of the instrument. Ion gun uses an argon gas and is commonly attached in most modern machines. Reliable and efficient vacuum systems employed in modern machines does not allow adsorbed layers to rebuild after the surface is cleaned. Development of efficient and reliable vacuum pumps over these developmental years is yet another important step in the commercialization of XPS machines. Vacuum levels of better than 10-7 torr are essential to increase the mean free path of electrons released from the sample surface. Thus, modern machines are equipped with high capacity ion, turbo or cryogenic pumps in their analytical chambers. Today, XPS has advanced from an applied physics laboratory to industry for use in quality control as well as analysis of contaminants and has taken a dominant role in microanalysis. Its uniqueness arises from the fact that it is considered non-destructive compared to other common micro-analytical techniques using the electron and ion excitation sources. Polymers and plastics could be analyzed since the binding energies of saturated and unsaturated bonds in atoms could be separated. Extremely thin layers could be analyzed including materials with layered structures. The technique, though did not advance for many years, has now opened a new window for research as well as applications in industry due to its ability to separate and measure the chemical shifts in bound elements. Principles

Panda, Binayak↗
NASA NTRS2019

Vapor Growth of Indium Monoiodide

Indium (I) iodide, InI, is part of a group of heavy metal iodides that can be used as room temperature radiation detectors. Other examples are HgI2, PbI2, BiI3, or TlPbI3. InI has several advantages, such as low toxicity, no solid phase transition (such as in HgI2), and no tendency to form polytypes (PbI2, BiI3 ). All binary iodides have layered structures and are quite soft, but InI is also the mechanically most stable compound of the binary compounds. Table 1 shows the main properties of InI in comparison with the other iodides and the most common room temperature radiation detector material, (Cd, Zn)Te. InI is typically grown by the unseeded Bridgman method using a nucleation tip, but Czochralski (CZ) growth has also been demonstrated. The resulting crystals have been used successfully for radiation detection, but both resistivity and mobility are usually well below theoretically predicted values. Physical vapor transport (PVT), although much slower than melt growth, is an alternative method and has been used to grow e.g. HgI2, PbI2, BiI3, CdTe. PVT growth should eliminate or reduce inclusions and impurities since it is based on sublimation, reduce intrinsic defects due to the lower growth temperature, and reduce dislocation densities due to reduced thermal and mechanical stress. As an example, PVT-grown CdTe showed a much improved structural quality compared to Bridgman- or THM-grown material.

Cröll, Arne↗
DOE OSTI2020

Layered-spinel electrodes for lithium batteries

An electrode for a lithium-ion cell comprising a ‘layered-spinel’ composite oxide material is disclosed. The ‘layered-spinel’ can be a material of formula xLiMO2.(1−x)LiyM′zO4, wherein 0 < x < 1; LiMO2 is a lithium metal oxide having a layered structure in which M comprises one or more transition metals and optionally lithium, and has a combined average oxidation state of +3; and LiyM′zO4 is a lithium metal oxide having a spinel structure, 1≤y≤1.33, 1.66≤z≤2, and M′ comprises one or more transition metals, and has a combined average metal oxidation state in the range of about +3.5 to about +4.

25 ENERGY STORAGE↗