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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 1,657 records · Page 92

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DOE OSTI2020

Site-wide occupancy assessment using camera traps for seven mammalian species at Los Alamos National Laboratory

Los Alamos National Laboratory (LANL or Laboratory) is committed to solving national security challenges through scientific excellence and has been serving the nation and northern New Mexico for over 70 years. Being located on the Pajarito Plateau in the eastern flanks of the Jemez Mountains, the Laboratory is surrounded by a rich diversity of plants and animals. It is common to see many different species of wildlife on Laboratory property; however, sometimes interactions with wildlife can be negative. Vehicle accidents with wildlife have become a common occurrence. With the current and ongoing expansion of the Laboratory on the Pajarito Plateau, it has the potential to further impact wildlife movement including large game species. Local agencies and tribal Pueblos rely on large game species and do not want these species to be restricted from moving across property boundaries. Temporal and spatial aspects of where wildlife occur on the site is a phenomena that is either not well understood in uncommon species or needs periodic reevaluation for common species. Estimating the distribution of multiple species across the landscape provides wildlife biologists with crucial information for monitoring and conserving animal populations in a particular area. Utilizing motion activated wildlife cameras, also known as camera traps, to monitor wildlife populations has become an essential tool for biologists. Camera traps are non-invasive and cost-effective and can document multiple elusive or uncommon wildlife species, such as carnivores, simultaneously. Occupancy modeling provides a flexible framework for the analysis of the distribution for multiple wildlife species. It explicitly recognizes whether a species is spatially common or rare (occupancy = ψ) and if that species is easy or hard to detect (detection probability = p ). Multispecies and multi-season occupancy models can detect trends in species occupancy because individual species may vary in seasonal movements, detection probability, and transition rates between habitats. In this study, we assessed the site as a whole to ascertain when and where medium and large mammal species are present. Understanding wildlife patterns at the Laboratory will better inform future management decisions regarding land use and development strategies. We placed motion activated wildlife cameras in a random systematic sampling design and used these data to create occupancy models. We tested for differences in single-species occupancy and detection probability by season of mammal species captured on 20 camera traps placed across the Laboratory in a 40 mi² (103 km²) area. We focus the interpretation of our findings on seven mammal species found during this study. They are Rocky Mountain elk ( Cervus canadensis nelsoni ; hereafter “elk”), mule deer ( Odocoileus hemionus ; hereafter “deer”), mountain lion ( Puma concolor ; hereafter “lion”), American black bear ( Ursus americanus ; hereafter “bear”), coyote ( Canis latrans ), bobcat ( Lynx rufus ), and gray fox ( Urocyon cinereoargenteus ; hereafter “fox”).

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS1973

A study of morphology, provenance, and movement of desert sand seas in Africa, Asia, and Australia

The author has identified the following significant results. The assembling of photomosaics from color prints of ERTS images has made possible the recognition and description of san patterns, and these are to be the basis of a worldwide classification of sand bodies. Progress has been as rapid as the acquisition of the bulk composite images will permit and for some areas the mosaics are now nearly complete. A second step, which consists of the accumulation and analysis of regional wind data, to be plotted as overlays for the dune patterns, is now underway and should soon give tangible results. Other aspects of the project include the gathering of ground truth in the form of air photographs, needed to interpret geomorphic forms and the sampling of sand deposits for analyzing the texture and composition of sand bodies. A start has been made on these studies in several selected areas.

Mckee, E. D.↗

NASA NTRS1973

A study of morphology, provenance, and movement of desert sand seas in Africa, Asia, and Australia

The author has identified the following significant results. The regional studies of sand seas made possible by analysis of ERTS-1 imagery have established that widespread patterns of eolian sand deposition exist in many places and that similarities and differences in these patterns can be measured and compared, on a worldwide scale. Analysis of the relationships of depositional patterns to controlling factors will require completion of the color mosaics of the test sites, and acquisition of adequate supporting ground truth data, especially wind data. Once analyses are complete, the results will be applicable to the regional study of ancient eolian sandstones. Such sandstones were formed many millions of years ago under conditions believed to be identical to those under which the sand seas that are observed being formed today. The understanding of the deposition of eolian sands provided by analysis of ERTS-1 imagery will be applicable to an understanding of the structure and distribution of ancient eolian sandstones and their potential as reservoirs of oil and water.

Mckee, E. D.↗

NASA NTRS1997

Immersive cyberspace system

An immersive cyberspace system is presented which provides visual, audible, and vibrational inputs to a subject remaining in neutral immersion, and also provides for subject control input. The immersive cyberspace system includes a relaxation chair and a neutral immersion display hood. The relaxation chair supports a subject positioned thereupon, and places the subject in position which merges a neutral body position, the position a body naturally assumes in zero gravity, with a savasana yoga position. The display hood, which covers the subject's head, is configured to produce light images and sounds. An image projection subsystem provides either external or internal image projection. The display hood includes a projection screen moveably attached to an opaque shroud. A motion base supports the relaxation chair and produces vibrational inputs over a range of about 0-30 Hz. The motion base also produces limited translation and rotational movements of the relaxation chair. These limited translational and rotational movements, when properly coordinated with visual stimuli, constitute motion cues which create sensations of pitch, yaw, and roll movements. Vibration transducers produce vibrational inputs from about 20 Hz to about 150 Hz. An external computer, coupled to various components of the immersive cyberspace system, executes a software program and creates the cyberspace environment. One or more neutral hand posture controllers may be coupled to the external computer system and used to control various aspects of the cyberspace environment, or to enter data during the cyberspace experience.

Park, Brian V.↗

NASA NTRS2014

Autonomous Real Time Requirements Tracing

One of the more challenging aspects of software development is the ability to verify and validate the functional software requirements dictated by the Software Requirements Specification (SRS) and the Software Detail Design (SDD). Insuring the software has achieved the intended requirements is the responsibility of the Software Quality team and the Software Test team. The utilization of Timeliner-TLX(sup TM) Auto- Procedures for relocating ground operations positions to ISS automated on-board operations has begun the transition that would be required for manned deep space missions with minimal crew requirements. This transition also moves the auto-procedures from the procedure realm into the flight software arena and as such the operational requirements and testing will be more structured and rigorous. The autoprocedures would be required to meet NASA software standards as specified in the Software Safety Standard (NASASTD- 8719), the Software Engineering Requirements (NPR 7150), the Software Assurance Standard (NASA-STD-8739) and also the Human Rating Requirements (NPR-8705). The Autonomous Fluid Transfer System (AFTS) test-bed utilizes the Timeliner-TLX(sup TM) Language for development of autonomous command and control software. The Timeliner-TLX(sup TM) system has the unique feature of providing the current line of the statement in execution during real-time execution of the software. The feature of execution line number internal reporting unlocks the capability of monitoring the execution autonomously by use of a companion Timeliner-TLX(sup TM) sequence as the line number reporting is embedded inside the Timeliner-TLX(sup TM) execution engine. This negates I/O processing of this type data as the line number status of executing sequences is built-in as a function reference. This paper will outline the design and capabilities of the AFTS Autonomous Requirements Tracker, which traces and logs SRS requirements as they are being met during real-time execution of the targeted system. It is envisioned that real time requirements tracing will greatly assist the movement of autoprocedures to flight software enhancing the software assurance of auto-procedures and also their acceptance as reliable commanders.

Plattsmier, George↗

NASA NTRS2014

Autonomous Real Time Requirements Tracing

One of the more challenging aspects of software development is the ability to verify and validate the functional software requirements dictated by the Software Requirements Specification (SRS) and the Software Detail Design (SDD). Insuring the software has achieved the intended requirements is the responsibility of the Software Quality team and the Software Test team. The utilization of Timeliner-TLX(sup TM) Auto-Procedures for relocating ground operations positions to ISS automated on-board operations has begun the transition that would be required for manned deep space missions with minimal crew requirements. This transition also moves the auto-procedures from the procedure realm into the flight software arena and as such the operational requirements and testing will be more structured and rigorous. The autoprocedures would be required to meet NASA software standards as specified in the Software Safety Standard (NASASTD- 8719), the Software Engineering Requirements (NPR 7150), the Software Assurance Standard (NASA-STD-8739) and also the Human Rating Requirements (NPR-8705). The Autonomous Fluid Transfer System (AFTS) test-bed utilizes the Timeliner-TLX(sup TM) Language for development of autonomous command and control software. The Timeliner- TLX(sup TM) system has the unique feature of providing the current line of the statement in execution during real-time execution of the software. The feature of execution line number internal reporting unlocks the capability of monitoring the execution autonomously by use of a companion Timeliner-TLX(sup TM) sequence as the line number reporting is embedded inside the Timeliner-TLX(sup TM) execution engine. This negates I/O processing of this type data as the line number status of executing sequences is built-in as a function reference. This paper will outline the design and capabilities of the AFTS Autonomous Requirements Tracker, which traces and logs SRS requirements as they are being met during real-time execution of the targeted system. It is envisioned that real time requirements tracing will greatly assist the movement of autoprocedures to flight software enhancing the software assurance of auto-procedures and also their acceptance as reliable commanders

Plattsmier, George I.↗

NASA NTRS1995

Investigations of the pathogenesis of acquired pendular nystagmus

We investigated the pathogenesis of acquired pendular nystagmus (APN) in six patients, three of whom had multiple sclerosis. First, we tested the hypothesis that the oscillations of APN are due to a delay in visual feedback secondary, for example, to demyelination of the optic nerves. We manipulated the latency to onset of visually guided eye movements using an electronic technique that induces sinusoidal oscillations in normal subjects. This manipulation did not change the characteristics of the APN, but did superimpose lower-frequency oscillations similar to those induced in normal subjects. These results are consistent with current models for smooth (non-saccadic) eye movements, which predict that prolongation of visual feedback could not account for the high-frequency oscillations that often characterize APN. Secondly, we attempted to determine whether an increase in the gain of the visually-enhanced vestibulo-ocular reflex (VOR), produced by viewing a near target, was accompanied by a commensurate increase in the amplitude of APN. Increases in horizontal or vertical VOR gain during near viewing occurred in four patients, but only two of them showed a parallel increase in APN amplitude. On the other hand, APN amplitude decreased during viewing of the near target in the two patients who showed no change in VOR gain. Taken together, these data suggest that neither delayed visual feedback nor a disorder of central vestibular mechanisms is primarily responsible for APN. More likely, these ocular oscillations are produced by abnormalities of internal feedback circuits, such as the reciprocal connections between brainstem nuclei and cerebellum.

NASA Program Space Physiology and Countermeasures↗

NASA NTRS1978

Application of global positioning system to determination of tectonic plate movements and crustal deformations

It is shown that pseudo-range measurements to four GPS satellites based on correlation of the pseudo random code transmissions from the satellites can be used to determine the relative position of ground stations which are separated by several hundred kilometers to a precision at the centimeter level. Carrier signal measurements during the course of passage of satellites over a pair of stations also yield centimeter precision in the relative position, but oscillator instabilities limit the accuracy. The accuracy of solutions based on either type of data is limited by unmodeled tropospheric refraction effects which would reach 5 centimeters at low elevation angles for widely separated stations.

Anderle, R. J.↗

DOE OSTI2022

Adatom-Driven Oxygen Intermixing during the Deposition of Oxide Thin Films by Molecular Beam Epitaxy

Thin film deposition from the vapor phase is a complex process involving adatom adsorption, movement, and incorporation into the growing film. While simulations have been able to capture key aspects of these processes to reproduce film morphology, these models typically ignore any subsurface diffusion that occurs. The results of these diffusion and intermixing processes are often observed experimentally, but cannot be explained by invoking bulk lattice diffusion at the deposition temperature. In this work, we present quantitative experimental data that reveals anion and cation intermixing over long length scales during the deposition of epitaxial Fe 2 O 3 and Cr 2 O 3 films and heterostructures by oxygen-plasma-assisted molecular beam epitaxy. We track this diffusion by incorporating well-defined tracer layers containing 18 O and/or 57 Fe, and measure their redistribution on the nanometer scale with atom probe tomography. Molecular dynamics simulations suggest potential intermixing events, which are then examined via nudged elastic band calculations. These reveal that adatoms on the film surface act to “pull up” subsurface O and Fe. Subsequent ring-like rotation mechanisms involving both adatom and subsurface anions then facilitate their mixing. A simple model incorporating these events qualitatively agrees with the experimental intermixing results. In addition to film deposition, these intermixing mechanisms may to be operant during other surface-mediated processes such as heterogeneous catalysis and corrosion.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2014

Studies of the physical aspects of intumescence using advance diagnostics methods

The use of intumescent paints as an active fire protection method has gained immense interest in recent years. A significant aspect of research has focused on studying the chemical aspects of the system to improve performance. The dynamics and physical aspects of intumescence in real time fire conditions are still unclear. The present research uses an experimental approach where diagnostics techniques such as thermal imaging camera was used to study intumescent characteristics that have been not been reported in great detail. T-panels are a substitute to the most commonly used part in construction, the I-beam. Studies were conducted using a cone calorimeter that provided a uniform heat flux through radiation on steel T-panel samples. The complex nature of char movement was recorded and a novel algorithm was used to track the growing char laye07r. The samples are designed to cater to different fire conditions. Therefore, the degree of intumescence was observed to be very different in the samples. The samples designed for low temperature cellulosic fires focus on high degree of intumesce. Whereas, mechanical strength is the focus for samples used in high temperature turbulent hydrocarbon fire conditions. The variation in the internal structure of the sample is presented. Furthermore, the phenomenon is phase shift is discussed. The phase shift is an essential part of the process of intumescence when the majority of intumescence occurs. It was observed to be different in all the samples. The movement of the samples is a property of great interest. This is because if any part of the substrate is exposed then the formulation does not meet strict commercialisation criterion. The movement was diagonal in nature as compared to flat panels where it is perpendicular. This is due tot the heating pattern of the plate that results in the web part of the panel to influence the growth of char on the flange part of the panel. A special case of char cracking is also highlighted and using image processing algorithm on the thermal imaging data. A quantitative method of analsysis is presented to an otherwise commonly qualitative nature of experimental study in this field.

36 MATERIALS SCIENCE↗

DOE OSTI2022

An Exact Algorithm for the Linear Tape Scheduling Problem

Magnetic tapes are often considered as an outdated storage technology, yet they are still used to store huge amounts of data. Their main interests are a large capacity and a low price per gigabyte, which come at the cost of a much larger file access time than on disks. With tapes, finding the right ordering of multiple file accesses is thus key to performance. Moving the reading head back and forth along a kilometer long tape has a non-negligible cost and unnecessary movements thus have to be avoided. However, the optimization of tape request ordering has rarely been studied in the scheduling literature, much less than I/O scheduling on disks. For instance, minimizing the average service time for several read requests on a linear tape remains an open question. Therefore, in this paper, we aim at improving the quality of service experienced by users of tape storage systems, and not only the peak performance of such systems. To this end, we propose a reasonable polynomial-time exact algorithm while this problem and simpler variants have been conjectured NP-hard. We also refine the proposed model by considering U-turn penalty costs accounting for inherent mechanical accelerations. Then, we propose a low-cost variant of our optimal algorithm by restricting the solution space, yet still yielding an accurate suboptimal solution. Finally, we compare our algorithms to existing solutions from the literature on logs of the mass storage management system of a major datacenter. This allows us to assess the quality of previous solutions and the improvement achieved by our low-cost algorithm. Aiming for reproducibility, we make available the complete implementation of the algorithms used in our evaluation, alongside the dataset of tape requests that is, to the best of our knowledge, the first of its kind to be publicly released.

Honoré, Valentin↗

DOE OSTI2024

Probabilistic projections of the Amery Ice Shelf catchment, Antarctica, under conditions of high ice-shelf basal melt

Abstract. Antarctica's Lambert Glacier drains about one-sixth of the ice from the East Antarctic Ice Sheet and is considered stable due to the strong buttressing provided by the Amery Ice Shelf. While previous projections of the sea-level contribution from this sector of the ice sheet have predicted significant mass loss only with near-complete removal of the ice shelf, the ocean warming necessary for this was deemed unlikely. Recent climate projections through 2300 indicate that sufficient ocean warming is a distinct possibility after 2100. This work explores the impact of parametric uncertainty on projections of the response of the Lambert–Amery system (hereafter “the Amery sector”) to abrupt ocean warming through Bayesian calibration of a perturbed-parameter ice-sheet model ensemble. We address the computational cost of uncertainty quantification for ice-sheet model projections via statistical emulation, which employs surrogate models for fast and inexpensive parameter space exploration while retaining critical features of the high-fidelity simulations. To this end, we build Gaussian process (GP) emulators from simulations of the Amery sector at a medium resolution (4–20 km mesh) using the Model for Prediction Across Scales (MPAS)-Albany Land Ice (MALI) model. We consider six input parameters that control basal friction, ice stiffness, calving, and ice-shelf basal melting. From these, we generate 200 perturbed input parameter initializations using space filling Sobol sampling. For our end-to-end probabilistic modeling workflow, we first train emulators on the simulation ensemble and then calibrate the input parameters using observations of the mass balance, grounding line movement, and calving front movement with priors assigned via expert knowledge. Next, we use MALI to project a subset of simulations to 2300 using ocean and atmosphere forcings from a climate model for both low- and high-greenhouse-gas-emission scenarios. From these simulation outputs, we build multivariate emulators by combining GP regression with principal component dimension reduction to emulate multivariate sea-level contribution time series data from the MALI simulations. We then use these emulators to propagate uncertainty from model input parameters to predictions of glacier mass loss through 2300, demonstrating that the calibrated posterior distributions have both greater mass loss and reduced variance compared to the uncalibrated prior distributions. Parametric uncertainty is large enough through about 2130 that the two projections under different emission scenarios are indistinguishable from one another. However, after rapid ocean warming in the first half of the 22nd century, the projections become statistically distinct within decades. Overall, this study demonstrates an efficient Bayesian calibration and uncertainty propagation workflow for ice-sheet model projections and identifies the potential for large sea-level rise contributions from the Amery sector of the Antarctic Ice Sheet after 2100 under high-greenhouse-gas-emission scenarios.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1975

Application of thermal scanning to the study of transverse mixing in rivers

Remote sensing has shown itself to be a valuable research tool in the study of transverse mixing in rivers. It is desirable, for a number of reasons, to study and predict the two-dimensional movement of pollutants in the region just downstream of a pollutant discharge point. While many of the more common pollutants do not exhibit a spectral signature, it was shown that the temperature difference between the pollutant and the receiving water could be successfully exploited by applying a mathematical model of mass transport processes to heat transport, and testing and calibrating it with thermal scanning data.

Eheart, J. W.↗

NASA NTRS1977

Effects of canard location on the aerodynamic characteristics of a sharp-nosed missile at Mach numbers of 1.5 and 2.0

A sharp-nosed missile model with nose-mounted canards and cruciform tail surfaces was tested in the Ames 6- by 6-foot wind tunnel to determine the contributions of the component aerodynamic surfaces on the static aerodynamic characteristics at Mach numbers of 1.5 and 2.0 and a Reynolds number of 1,000,000 based on body diameter. Effect of canard location (at three different axial positions) was investigaed. Data were obtained at angles of attack ranging from 3 deg to 12 deg, roll angles of 0 deg and 45 deg, and canard-deflection angles from 3 deg to 15 deg for various stages of model build-up (i.e., with and without canard and/or tail surfaces). The canard in the most aft position was least effective in trimming the model. With movement of the canard to the most forward position, the model was trimmable at angles of attack up to about 5 deg or 6 deg with panel deflections of 9 deg.

Kassner, D. L.↗

NASA NTRS1984

A preliminary analysis of flight data from the AFTI/F-16 airplane

Flight test data from the AFTI/F-16 airplane are analyzed. Two flight control system modes (Independent Backup Unit and Standard Normal Mode) are considered. Estimated stability and control derivatives are compared with values from the wind tunnel and F-16A flight tests. Modeling difficulties are shown to arise due to the near-neutral static stability of the airplane and the number of coordinated control surface movements commanded in the Standard Normal Mode.

Batterson, J. G.↗

NASA NTRS1992

Atmospheric gravitational influence on geodetic satellite orbits - Starlette analysis

The atmosphere is constantly in motion. The changing gravitational force due to the air mass movement will slightly perturb the orbit of a satellite. As the instrument accuracy for geodetic satellites improves, failure to model this perturbation can result in significant systematic errors in the orbit determination. The latter, in turn, will degrade the Earth's gravity solutions. A direct modeling technique to analyze the atmospheric gravitational influence on geodetic satellite is developed. We use the global surface pressure data from the ECMWF Initial Analysis Database to compute the gravitational force due to atmospheric perturbation exerted on given satellite as a function of time during selected orbital arcs. Satellite Laser Ranging (SLR) tracking data for selected Starlette (altitude 900 km) orbital arcs are used to test the computed force model. Although only a slight reduction in the rms residuals is observed when the atmospheric gravitational perturbation is included in the force model for data reduction of the SLR data, significant improvement is obtained in the predictability of the satellite orbit. Comprehensive studies involving more definitive test criteria and more refined models are still needed.

Chao, B. F.↗

NASA NTRS2022

Diverse Responses of Multiple Satellite-Derived Vegetation Greenup Onsets to Dry Periods in the Amazon

Satellite-derived vegetation greenness and seasonal dynamics in the Amazon have generated considerable academic debate over the past two decades. Despite this, the phenological timing of Amazon forests and, in particular their responses to dry periods, remain poorly understood. Here we explicitly identify the diverse timing of vegetation canopy greenup onsets from 10-min geostationary satellite observations, and compute the timing of both the start and end of dry periods from daily precipitation data. We, for the first time, reveal that the Amazon vegetation canopy regularly experiences two cycles of greenup onsets during a year. The occurrence of greenup onset varies diversely from the start to end of the dry periods, but demonstrates regular shifts in local areas, although irregular shifts across the region. The multiple greenup onsets show complex spatial shifts, which closely follow the spatial movement of dry periods. The results provide a new insight into our understanding of the complexity of Amazonian vegetation canopy dynamics during dry periods, which could significantly improve the simulation of carbon and water cycles.

Satellite-Derived Vegetation↗

DOE OSTI2017

Terrace Geochemistry at the Shiprock, New Mexico, Disposal Site - WM2017-17232 Initial Phase

The objective of this investigation was to identify and differentiate potential non- mill-related water inputs to a shallow terrace groundwater system through the use of aqueous chemical and isotopic tracers at a former uranium- and vanadium-ore processing facility. Terrace groundwater in the vicinity of the Shiprock, New Mexico, site is hypothesized to be largely anthropogenic because natural rates of recharge in the terrace are likely insufficient to sustain a continuous water table in the terrace alluvial system, as observed in several analogue terrace locations east of the site and in response to post-mill dewatering efforts across the site. The terrace is composed of alluvial sand and gravel and weathered and unweathered Mancos Shale. Terrace groundwater exists and flows in the alluvium and to a much less extent in the Mancos Shale. Historical data established that in both the terrace and floodplain below the terrace, mill-derived uranium and sulfate is found primarily in the alluvium and the upper portion of the weathered Mancos Shale. Groundwater extraction is being conducted in the vicinity of former mill operations and in washes and seeps to dewater the formation and remove contamination, thus eliminating these exposure pathways and minimizing movement to the floodplain. However, past and present contribution of non-mill anthropogenic water sources may be hindering the dewatering effort, resulting in reduced remedy effectiveness. Groundwater source signatures can be determined based on chemical and isotopic ratios and are used to help identify and delineate both mill and non-mill water contributions. Aqueous chemical and isotopic tracers, such as 234U/238U activity ratios and uranium concentrations, δ34S sulfate and sulfate concentrations, tritium concentrations, and δ2Hwater and δ18O water are being used in this Phase I study. The aqueous chemical and isotopic analysis has identified areas on the terrace where groundwater is derived from mill-related activities and areas where the groundwater is associated with non-mill activities. A separate field effort of Phase II work will follow, including investigating additional locations for these isotopes and examination of δ18Osulfate , δ34Ssulfate , and chlorofluorocarbon signatures.

54 ENVIRONMENTAL SCIENCES↗