SEARCH · Search NASA

Results for “cover complexity”

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.

SourceResearch connectionFrom yearThrough year

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

At least 775 records · Page 43

All sources NASA NTRS DOE OSTI

DOE OSTI2020

Deep Eutectic Solvents: A Review of Fundamentals and Applications

Deep eutectic solvents (DESs) are an emerging class of mixtures characterized by significant depressions in melting points compared to those of the neat constituent components. These green materials are promising for applications as inexpensive ’designer’ solvents exhibiting a host of tunable physicochemical properties. Here, a detailed review of the current literature reveals the lack of predictive understanding of the microscopic mechanisms that govern the structure-property relationships in this class of solvents. Complex hydrogen bonding behavior is postulated as the root cause of their melt-ing point depressions and physicochemical properties; to understand these hydrogen bonded networks, it is imperative to study these systems as dynamic entities using both simulations and experiments. This review emphasizes recent research efforts in order to elucidate the next steps needed to develop a fundamental framework for understanding DESs. It covers recent developments in DES research, frames outstanding scientific questions, and identifies gainful research thrusts that would advance the field towards predictive models and fundamental understanding of these solvents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

Molecular Imaging Reveals Two Distinct Mixing States of PM 2.5 Particles Sampled in a Typical Beijing Winter Pollution Case

Mixing states of aerosol particles are crucial for understanding the role of aerosols in influencing air quality and climate. However, a fundamental understanding of the complex mixing states is still lacking because most traditional analysis techniques only reveal bulk chemical and physical properties with limited surface and 3-D information. In this research, 3-D molecular imaging enabled by ToF-SIMS was used to elucidate the mixing states of PM 2.5 samples obtained from a typical Beijing winter haze event. In light pollution cases, a thin organic layer covers separated inorganic particles, while in serious pollution cases, ion exchange and an organic-inorganic mixing surface on large-area particles were observed. Finally, the new results provide key 3-D molecular information of mixing states, which is highly desirable for reducing uncertainty and bias in representing aerosol-cloud interactions in current Earth System Models, and improving the understanding of aerosols on air quality and human health.

3-D molecular imaging↗

NASA NTRS1988

Niebla ceruchis from Laguna Figueroa: dimorphic spore morphology and secondary compounds localized in pycnidia and apothecia

During and after the floods of 1979-80 Niebla ceruchis growing epiphytically on Lycium brevipes was one of the dominant aspects of the vegetation in the coastal dunal complex bordering the microbial mats at Laguna Figueroa, Baja California Norte, Mexico. The lichen on denuded branches of Lycium was far more extensively distributed than Lycium lacking lichen. Unusual traits of this Niebla ceruchis strain, namely localization of lichen compounds in the mycobiont reproductive structures (pycnidia and apothecia) and simultaneous presence of bilocular and quadrilocular ascospores, are reported. The abundance of this coastal lichen cover at the microbial mat site has persisted through April 1988.

NASA Discipline Exobiology↗

NASA NTRS2004

Image Analysis via Fuzzy-Reasoning Approach: Prototype Applications at NASA

A set of imaging techniques based on Fuzzy Reasoning (FR) approach was built for NASA at Kennedy Space Center (KSC) to perform complex real-time visual-related safety prototype tasks, such as detection and tracking of moving Foreign Objects Debris (FOD) during the NASA Space Shuttle liftoff and visual anomaly detection on slidewires used in the emergency egress system for Space Shuttle at the launch pad. The system has also proved its prospective in enhancing X-ray images used to screen hard-covered items leading to a better visualization. The system capability was used as well during the imaging analysis of the Space Shuttle Columbia accident. These FR-based imaging techniques include novel proprietary adaptive image segmentation, image edge extraction, and image enhancement. Probabilistic Neural Network (PNN) scheme available from NeuroShell(TM) Classifier and optimized via Genetic Algorithm (GA) was also used along with this set of novel imaging techniques to add powerful learning and image classification capabilities. Prototype applications built using these techniques have received NASA Space Awards, including a Board Action Award, and are currently being filed for patents by NASA; they are being offered for commercialization through the Research Triangle Institute (RTI), an internationally recognized corporation in scientific research and technology development. Companies from different fields, including security, medical, text digitalization, and aerospace, are currently in the process of licensing these technologies from NASA.

Dominguez, Jesus A.↗

NASA NTRS2019

Titan's Neutral Atmosphere Seasonal Variations up to the End of the Cassini Mission

In this paper we report new results concerning the seasonal atmospheric evolution near Titan's poles and equator in terms of temperature and composition using nadir spectra acquired by the Cassini Composite Infrared Spectrometer (CIRS) at high spectral resolution during the last year of the Cassini mission in 2017 complementing previous investigations covering almost two Titan seasons. In recent previous papers (Coustenis et al., 2016, 2018), we have reported on monitoring of Titan's stratosphere near the poles after the mid-2009 northern spring equinox. In particular we have reported on the observed strong temperature decrease and compositional enhancement above Titan's southern polar latitudes since 2012 and until 2014 of several trace species, such as complex hydrocarbons and nitriles, which were previously observed only at high northern latitudes. This effect accompanied the transition of Titan's seasons from northern winter in 2002 to northern summer in 2017, while at that latter time, the southern hemisphere was entering winter. Our new data, acquired in 2017 and analyzed here, are important because they are the only ones recorded since 2014 close to the south pole in the mid-infrared nadir mode at high resolution. A large temperature increase in the southern polar stratosphere (by 10–50 K in the 0.1 mbar–0.01 mbar pressure range) is found associated with a change in the temperature profile's shape. The 2017 observations also show a related significant decrease in most of the southern abundances which must have started sometime between 2014 and 2017. For the north, the spectra indicate a continuation of the decrease of the abundances which we first reported to have started in 2015 and small temperature variations. We discuss comparisons with other results and with current photochemical and dynamical models which could be updated and improved by the new constraints set by the findings presented here.

A Coustenis↗

NASA NTRSDate not supplied

Health Monitoring and Prognostics in Li-ion Batteries

Space applications need to overcome a very critical challenge of predicting remaining useful life of its critical systems/subsystems, with batteries being one of them. Batteries, power electronics conditioning system and motors and one of the most critical systems. Similarly in case of electric aircrafts, computing remaining flying time is safety-critical, since an aircraft that runs out of power (battery charge) while in the air will eventually lose control leading to catastrophe. To tackle and solve the prediction problem, it is essential to have awareness of the current state and health of the system, especially since it is necessary to perform condition-based predictions. To be able to accurately predict the future state of any system, it is required to possess knowledge of its current and future operations. Given models of the current and future system behavior, the general approach of model-based prognostics can be employed as a solution to the prior stated prediction problem. Two approaches are presented with battery prognostics application. The first approach presentation covers a physics based-modeling approach implemented for battery prognostics. Given models of the current and future system behavior, a general approach of model-based prognostics can be employed as a solution to the prediction problem and further for decision making. A second hybrid framework for fusing information from physics-based performance models along with deep learning algorithms for prognostics of complex safety critical systems i.e. batteries is presented. In this framework, physics-based performance models infer unobservable model parameters related to the system's components health solving a calibration problem in the deep learning approach.

Batteries↗

NASA NTRSDate not supplied

Health Monitoring and Prognostics in Li-ion Batteries

Battery Prognostics↗

NASA NTRS2010

Geological Map of the Fredegonade (V-57) Quadrangle, Venus: Status Report

The Fredegonde quadrangle (V-57; 50-75degS, 60-120degE, Fig. 1) corresponds to the northeastern edge of Lada Terra and covers a broad area of the topographic province of midlands (0-2 km above MPR [1,2]). This province is most abundant on Venus and displays a wide variety of units and structures [3-11]. The sequence of events that formed the characteristic features of the midlands is crucially important in understanding of the timing and modes of evolution of this topographic province. Topographically, the Fredegonde quadrangle is within a transition zone between the elevated portion of Lada Terra to the west (Quetzalpetlatl-Boala Coronae rise, approx.3.5 km) and the lowland of Aino Planitia to the north and northeast (approx.-0.5 km). This transition is one of the key features of the V-57 quadrangle. In this respect the quadrangle resembles the region of V-4 quadrangle [12] that shows transition between the midlands and the lowlands of Atalanta Planitia. One of the main goals of our mapping within the V-57 quadrangle is comparison of this region with the other transitional topographic zones such as quadrangles V-4 and V-3 [13]. The most prominent features in the V-57 quadrangle are linear deformational zones of grooves and large coronae. The zones characterize the central and NW portions of the map area and represent broad (up to 100s of km wide) ridges that are 100s of m high. Morphologically and topographically, these zones are almost identical to the groove belt/corona complexes at the western edge of Atalanta Planitia [12]. Within the Fredegonde area, however, the zones are oriented at high angles to the general trend of elongated Aino Planitia, whereas within the V-4 quadrangle they are parallel to the edge of Atalanta Planitia. Relatively small (100s of km across, 100s of m deep) equidimensional basins occur between the corona-groove-chains in the area of V-57 quadrangle. These basins are similar to those that populate the area of the V-3 quadrangle [13]. Broad regional plains cover the surface of the basins in both regions. In contrast to Fredegonde, the area of the V-3 quadrangle displays a greater diversity of units and features [13]. Here we describe units that make up the surface within the V-57 quadrangle and present a summary of our geological map that shows the areal distribution of the major groups of units.

Ivanov, M. A.↗

DOE OSTI2021

Roadmap for Sustainable Mixed Ionic–Electronic Conducting Membranes

Mixed ionic-electronic conducting (MIEC) membranes have gained growing interest recently for various promising environmental and energy applications, such as H 2 and O 2 production, CO 2 reduction, O 2 and H 2 separation, CO 2 separation, membrane reactors for production of chemicals, cathode development for solid oxide fuel cells, solar-driven evaporation and energy-saving regeneration as well as electrolyzer cells for power-to-X technologies. The purpose of this roadmap, written by international specialists in their fields, is to present a snapshot of the state-of-the-art, and provide opinions on the future challenges and opportunities in this complex multidisciplinary research field. As the fundamentals of using MIEC membranes for various applications become increasingly challenging tasks, particularly in view of the growing interdisciplinary nature of this field, a better understanding of the underlying physical and chemical processes is also crucial to enable the career advancement of the next generation of researchers. As an integrated and combined article, it is hoped that this roadmap, covering all these aspects, will be informative to support further progress in academics as well as in the industry-oriented research toward commercialization of MIEC membranes for different applications.

36 MATERIALS SCIENCE↗

NASA NTRS1976

Ages of flow units in the lunar nearside maria based on Lunar Orbiter IV photographs

A map dividing the lunar nearside maria into six units each of uniform age was compiled from Lunar Orbiter IV photographs. Relative ages were determined using a crater morphology technique. Relative ages were then converted to absolute ages by comparison to a curve calibrated from Apollo and Luna sample data; three of the six units, including the two youngest (about 3.1 and 2.6 b.y. old), were not sampled by Apollo or Luna. Vast regions in the western maria are covered by these young flows. The old flows (about 3.75 b.y. in age) are found to occur mostly in the eastern maria. A comparison of the age units derived from these data with those units derived from other remote-sensing data provide good agreement in the location of unit boundaries. These data also indicate that the emplacement history of mare basalt types is more complex than was earlier thought.

Boyce, J. M.↗

NASA NTRS1982

Evaluation of land cover change detection techniques using Landsat MSS data

Four techniques for detecting land cover change with Landsat MSS data were evaluated for a test site in east central Louisiana where forestland is being converted to cropland and pasture. The four techniques were: (1) post-classification differencing, (2) composite classification, (3) radiance value shift, and (4) regression modeling. Three of the techniques gave acceptable accuracies. The main differences were the amount of computer time and the level of complexity.

Burns, G. S.↗

NASA NTRS1996

Retrieval of Surface Snow Grain Size and Melt Water from AVIRIS Spectra

The Earth's energy balance and hydrology are affected by the distribution and characteristics of snow cover on the surface. Snow grain size and snow melt influence surface albedo and hydrology. A model of snow reflectance that depends on both grain size and surface melt water was developed to derive these parameters from remote spectral measurements. This reflectance model is based on a discrete ordinate radiative transfer approach that uses Mie calculations of snow optical properties, which are based on the complex refractive index of ice and water. This snow model was linked to an atmospheric radiative transfer code and a nonlinear least squares fitting algorithm. The resulting combined algorithm was applied to an AVIRIS snow data set acquired over Mammoth Mountain, California. Maps of grain size and surface snow melt were generated that are consistent with the expected ranges and distributions for conditions at the site.

Green Robert O.↗

NASA NTRS1984

Tectonic lineaments in the cenozoic volcanics of southern Guatemala: Evidence for a broad continental plate boundary zone

The northern Caribbean plate boundary has been undergoing left lateral strike slip motion since middle Tertiary time. The western part of the boundary occurs in a complex tectonic zone in the continental crust of Guatemala and southernmost Mexico, along the Chixoy-Polochic, Motogua and possibly Jocotan-Chamelecon faults. Prominent lineaments visible in radar imagery in the Neogene volcanic belt of southern Guatemala and western El Salvador were mapped and interpreted to suggest southwest extensions of this already broad plate boundary zone. Because these extensions can be traced beneath Quaternary volcanic cover, it is thought that this newly mapped fault zone is active and is accommodating some of the strain related to motion between the North American and Caribbean plates. Onshore exposures of the Motoqua-Polochic fault systems are characterized by abundant, tectonically emplaced ultramafic rocks. A similar mode of emplacement for these off shore ultramafics, is suggested.

Baltuck, M.↗

NASA NTRS1995

Alternative beam configuration for a Canadian Ka-band satellite system

Satellite systems operating in the Ka-band have been proposed to offer wide band personal communications services to fixed earth terminals employing small aperture antennas as well as to mobile terminals. This requirement to service a small aperture antenna leads to a satellite system utilizing small spot beams. The traditional approach is to cover the service area with uniform spot beams which have been sized to provide a given grade of service at the worst location over the service area and to place them in a honeycomb pattern. In the lower frequency bands this approach leads to a fairly uniform grade of service over the service area due to the minimal effects of rain on the signals. At Ka-band, however, the effects of rain are quite significant. Using this approach over a large service area (e.g. Canada) where the geographic distribution of rain impairment varies significantly yields an inefficient use of satellite resources to provide a uniform grade of service. An alternative approach is to cover the service area using more than one spot beam size in effect linking the spot beam size to the severity of the rain effects in a region. This paper demonstrates how for a Canadian Ka-band satellite system, that the use of two spot beam sizes can provide a more uniform grade of service across the country as well as reduce the satellite payload complexity over a design utilizing a single spot beam size.

Hindson, Daniel J.↗

NASA NTRS2010

The Importance of HRA in Human Space Flight: Understanding the Risks

Human performance is critical to crew safety during space missions. Humans interact with hardware and software during ground processing, normal flight, and in response to events. Human interactions with hardware and software can cause Loss of Crew and/or Vehicle (LOCV) through improper actions, or may prevent LOCV through recovery and control actions. Humans have the ability to deal with complex situations and system interactions beyond the capability of machines. Human Reliability Analysis (HRA) is a method used to qualitatively and quantitatively assess the occurrence of human failures that affect availability and reliability of complex systems. Modeling human actions with their corresponding failure probabilities in a Probabilistic Risk Assessment (PRA) provides a more complete picture of system risks and risk contributions. A high-quality HRA can provide valuable information on potential areas for improvement, including training, procedures, human interfaces design, and the need for automation. Modeling human error has always been a challenge in part because performance data is not always readily available. For spaceflight, the challenge is amplified not only because of the small number of participants and limited amount of performance data available, but also due to the lack of definition of the unique factors influencing human performance in space. These factors, called performance shaping factors in HRA terminology, are used in HRA techniques to modify basic human error probabilities in order to capture the context of an analyzed task. Many of the human error modeling techniques were developed within the context of nuclear power plants and therefore the methodologies do not address spaceflight factors such as the effects of microgravity and longer duration missions. This presentation will describe the types of human error risks which have shown up as risk drivers in the Shuttle PRA which may be applicable to commercial space flight. As with other large PRAs of complex machines, human error in the Shuttle PRA proved to be an important contributor (~12 percent) to LOCV. An existing HRA technique was adapted for use in the Shuttle PRA, but additional guidance and improvements are needed to make the HRA task in space-related PRAs easier and more accurate. Therefore, this presentation will also outline plans for expanding current HRA methodology to more explicitly cover spaceflight performance shaping factors.

Hamlin, Teri↗

NASA NTRS2018

A 3D Citizen Science Video Game for NeMO-Net, the NASA Neural Multi-Modal Observation and Training Network for Global Coral Reef Assessment

NeMO-Net, the NASA neural multi-modal observation and training network for global coral reef assessment, is an open-source deep convolutional neural network aimed at accurately assessing the present and past dynamics of coral reef ecosystems through determination of percent living cover and morphology. We present here the active learning component of the project, which consists of an interactive video game prototype for tablet and mobile devices where players are able to intuitively label morphology classifications over mm-scale 3D coral reef imagery. Active learning applications present a novel methodology for engaging the public while efficiently providing large-scale training and test data for increasingly complex and data-intensive machine learning algorithms. NeMO-Net trains players on domain-specific knowledge through interactive tutorials and periodically checks players' input against pre-classified coral imagery to gauge their accuracy and utilize in-game mechanics to provide personalized classification training. Players can rate the classifications of other players, unlock rewards and join a global community as they explore and classify coral reefs and other shallow marine environments.

Citizen Science↗

NASA NTRS1993

Reversible non-volatile switch based on a TCNQ charge transfer complex

A solid-state synaptic memory matrix (10) having switchable weakly conductive connections at each node (24) whose resistances can be selectably increased or decreased over several orders of magnitude by control signals of opposite polarity, and which will remain stable after the signals are removed, comprises an insulated substrate (16), a set of electrical conductors (14) upon which is deposited a layer (18) of an organic conducting polymer, which changes from an insulator to a conductor upon the transfer of electrons, such as polymerized pyrrole doped with 7,7,8,8-tetracyanoquinodimethane (TCNQ), covered by a second set of conductors (20) laid at right angles to the first.

Nagasubramanian, Ganesan↗

DOE OSTI2022

Multiphysics FISPACT-II and TENDL-2019 simulation: neutron-induced damage metrics

Nuclear interactions can be the source of atomic displacement, irradiation-induced defects and transmutation in structural materials. Such quantities are derived from, or can be correlated to, nuclear kinematic simulations of primary atomic energy distributions spectra and the quantification of the numbers of secondary defects produced per primary as a function of the available recoils, residual and emitted, energies. Recoil kinematics of neutral, residual, gas, proton, alpha particle emissions are now more rigorously treated based on recent, complete and enhanced nuclear data parsed in state-of-the-art processing tools. Defect production metrics are the starting point in the complex problem of correlating and simulating the behaviour of materials under irradiation, as experimental information is rare or scattered. Detailed, segregated primary knock-on-atom metrics are now becoming available as the starting point of further simulation processes of isolated and clustered defects in material lattices. This allows more materials, lattices, neutron incident energy ranges, and irradiation conditions to be explored with sufficient data to adequately cover both standard and novel applications and materials: the broader reactor applications landscape. The damage metrics of of materials are systematically explored under typical but different reactor's type environment. The inventory code FISPACT-II combined with the enhanced nuclear data forms of the TENDL-2019 libraries allow one to not only calculate dpa from mostly scattering events but to also properly predict gas production, nuclear heating and transmutation under the same conditions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗