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At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Field Mapper for Superconducting Torus Magnet for the Jefferson Lab 12GeV Upgrade

As part of the Jefferson Lab 12 GeV upgrade, the Hall B magnet system requires two conduction cooled superconducting magnets ? a Torus and a Solenoid. The Torus consists of 6 trapezoidal coils connected in series with an operating current of 3770 A. During commissioning of the torus magnet, field mapping was carried out at different levels of operating current in order to determine the field profile and field error table. In order to meet the physics requirement of the field accuracy we need magnetic field strength measurements which are accurate at the 0.1% level, and we need to know radius and azimuth to 0.1 mm and z to 0.5 mm. The center line of the torus magnet is approximately 6 m from ground level and the overall height of the torus magnet is approximately 8.5 m. There is also limited space around the magnet and in between the coils. Field mapping had to be carried out along the Z axis (i.e. along the bore) and at 4 radial locations between each coil. These restrictions provided certain challenges for the magnetic field mapping task. The mapper prototype was built and tested prior to use on the Torus itself. In this presentation the field mapper design, prototyping and actual data collection procedure will be presented.

Rajput-Ghoshal, Renuka↗
DOE OSTI2017

Radiation Source Mapping with Bayesian Inverse Methods

In this work, we present a method to map the spectral and spatial distributions of radioactive sources using a limited number of detectors. Locating and identifying radioactive materials is important for border monitoring, in accounting for special nuclear material in processing facilities, and in cleanup operations following a radioactive material spill. Most methods to analyze these types of problems make restrictive assumptions about the distribution of the source. In contrast, the source mapping method presented here allows an arbitrary three-dimensional distribution in space and a gamma peak distribution in energy. To apply the method, the problem is cast as an inverse problem where the system’s geometry and material composition are known and fixed, while the radiation source distribution is sought. A probabilistic Bayesian approach is used to solve the resulting inverse problem since the system of equations is ill-posed. The posterior is maximized with a Newton optimization method. The probabilistic approach also provides estimates of the confidence in the final source map prediction. A set of adjoint, discrete ordinates flux solutions, obtained in this work by the Denovo code, is required to efficiently compute detector responses from a candidate source distribution. These adjoint fluxes form the linear mapping from the state space to the response space. The test of the method’s success is simultaneously locating a set of 137 Cs and 60 Co gamma sources in a room. This test problem is solved using experimental measurements that we collected for this purpose. Because of the weak sources available for use in the experiment, some of the expected photopeaks were not distinguishable from the Compton continuum. However, by supplanting 14 flawed measurements (out of a total of 69) with synthetic responses computed by MCNP, the proof-of-principle source mapping was successful. The locations of the sources were predicted within 25 cm for two of the sources and 90 cm for the third, in a room with an ~4-x 4-m floor plan. Finally, the predicted source intensities were within a factor of ten of their true value.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2023

TRACER-MAP_2022_absorption_coefficient

Absorption coefficient for PM2.5 measured by the Tri-color Absorption Photometer averaged every 2 minutes for July-August 2022. The location of the measurement is indicated by latitude and longitude coordinates; TRACER-MAP included time at the AMF site in La Porte and additional sites around Houston. Three wavelengths are reported: 365, 520 and 640 nm. The AAE is also reported using the three wavelengths. The data is reported as 2 minute averages.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

RNA-exporting machine in action

A tiny motor tasked with one of nature's biggest jobs is now better understood. The molecular machinery that helps export messenger RNA from a cell's nucleus has been structurally mapped at the Advanced Light Source, a synchrotron located at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab). In this simulation, Gle1 (yellow) binds Dbp5 (green and blue-grey) causing Dbp5 to release RNA (orange). The movie begins with Dbp5 bound to RNA and then transitions to the Gle1-Dbp5 state, the step that jettisons RNA. The simulation then plays in reverse to mimic RNA and ATP dependent closing of Dbp5 and release of Gle1 (Movie courtesy of Karsten Weis's and James Berger's labs).

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Volumetric calibration of a plenoptic camera

Here, the volumetric calibration of a plenoptic camera is explored to correct for inaccuracies due to real-world lens distortions and thin-lens assumptions in current processing methods. Two methods of volumetric calibration based on a polynomial mapping function that does not require knowledge of specific lens parameters are presented and compared to a calibration based on thin-lens assumptions. The first method, volumetric dewarping, is executed by creation of a volumetric representation of a scene using the thin-lens assumptions, which is then corrected in post-processing using a polynomial mapping function. The second method, direct light-field calibration, uses the polynomial mapping in creation of the initial volumetric representation to relate locations in object space directly to image sensor locations. The accuracy and feasibility of these methods is examined experimentally by capturing images of a known dot card at a variety of depths. Results suggest that use of a 3D polynomial mapping function provides a significant increase in reconstruction accuracy and that the achievable accuracy is similar using either polynomial-mapping-based method. Additionally, direct light-field calibration provides significant computational benefits by eliminating some intermediate processing steps found in other methods. Finally, the flexibility of this method is shown for a nonplanar calibration.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

Updated Subsurface Data Base For Bear Creek Valley, Chestnut Ridge, And Parts Of Bethel Valley On The U.S. Department of Energy Oak Ridge Reservation

This document represents a compilation of location, construction, and hydrologic information relating to boreholes, groundwater monitoring wells, and surface water locations that have been installed/established at the Y-12 National Security Complex (Y-12) through August 2013. To date, a total of 1422 boreholes and wells have been installed in and around the Y-12 area. Of those, 835 existing boreholes and wells continue to be utilized for groundwater monitoring programs, research, remedial investigations, plume characterization and delineation studies, and various other hydrogeologic endeavors. In addition, 215 surface water locations, such as rivers, streams, seeps, springs, lakes, ponds, and building sumps are included in this database. General data about boreholes and wells included in the database are survey coordinates, survey system, elevations, alternative names and well status. Surface water location information (Appendix I) includes name, alias, functional area, northing and easting coordinates, survey system, map number and sampling history. Tabulated construction data include total depth, completion method, borehole diameter, casing and screen materials, casing and screen diameters, casing and screen depths, filter pack depths, open-hole intervals, and open-hole diameters. Hydrogeological data summarized in this document include the aquifer monitored by the completion interval, depth to weathered and fresh bedrock, formations penetrated, well sampling history, and whether rock core and geophysical logs were obtained. This document (which is the sixth revision to Y/TS–881 and the ninth overall update of a previous compilation) is published on a regular basis by the Y-12 Groundwater Protection Program (GWPP), which serves as custodian of drilling records and well construction data for the network of wells and other groundwater monitoring stations at Y-12. The tabulations in this database are arranged in appendices of like information. An example application of the data compiled in this document would be the evaluation of the suitability of wells for continued use in groundwater investigations and monitoring studies. Other uses may include: the siting of hydrogeological characterization activities, background evaluations of sites prior to initiation of new drilling activities, and hydrogeological review of selected sites prior to the initiation of remedial actions or new construction activity. Existing boreholes, wells, and surface water locations are presented on a series of maps (Appendix K). Boreholes and wells that have been plugged and abandoned, destroyed, could not be located, or otherwise are of unknown status/condition appear on a second series of maps of identical coverage (Appendix L).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Characterization of the Pulsed Radiation Environment in FREC-II at the ACRR

Ongoing tests at the Annular Core Research Reactor (ACRR) at Sandia National Laboratories aim to measure temperature and strain in materials exposed to a transient neutron-photon environment. Radiation transport and finite element analysis codes are used to predict the thermal-structural response of test articles exposed in the reactor. Strain and temperature sensors fielded on test articles provide validation data for finite element models, while active and passive radiation dosimetry provides data for MCNP models. The ACRR is able to provide pulse energies of 40 - 300 MJ per pulse with pulse times of 7 - 100 milliseconds. The pulse power is higher than many of the other research reactors due to its unique high heat capacity UO{sub 2}-BeO fuel in the central reactor. Additionally, the Fuel Ringed External Cavity (FREC-II) contains U-ZrH fuel. Future tests at the ACRR plan to field test assemblies in the Fuel Ringed External Cavity (FREC-II) and expose the test articles to the transient anisotropic radiation field experienced in the cavity. The FREC-II is coupled with the ACRR core and is used to test larger specimens, and the radiation environment can be shaped/modified to the needs of the experiment. The FREC-II was designed to provide an irradiation cavity with a strong flux gradient favoring the central cavity side. Neutron fluence also varies by height in the cavity, with a peak level slightly below the fuel rod vertical centerline. Tests were conducted in 2014 to measure the thermal-structural response of test articles exposed in the central cavity. Those tests in the central cavity fielded Nickel activation foils to record the neutron fluence at various locations around the test assembly. Foil data was later used to highlight uncertainties between thermo-structural response models and the measured temperature and strain. Studies performed in 2015 exposed large arrays of activation foils and thermo-luminescent dosimeters (TLD) in the FREC-II cavity in order to map out the neutron and photon spectrum at many locations. This type of passive measurement was shown to be too simple for performing thermo-structural simulations of a test article in response to multiple pulsed-reactor exposures. The Depleted Uranium Strain and Temperature - Enhanced Response (DUSTER-II) experiments will expose test assemblies to reactor pulses in the FREC-II cavity. To prepare for these experiments, the MCNP model will be compared with June 2016 experimental results from the pulses with the FREC-II coupled with the ACRR. These comparisons will provide an accurate model to be implemented in further studies. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2022

Physics-informed neural networks for identification of material properties using standing waves

A metallic structure in its initial stage of failure involves plastic deformation or environmental degradation that changes the elastic modulus and density. This work presents the detection of change in wave velocity (a function of elastic modulus and density) as a system identification problem. A physics-informed neural network (PINN) is proposed to solve the system identification problem. The PINN takes the spatial coordinates of scanning locations and time as inputs and provides the displacement and wave velocity as outputs. The governing partial differential equation of standing waves in a rod is incorporated into the neural network as physics in the form of a loss function. The wave velocity vector is randomly initiated. During the training of the network, physics is used to determine and update the wave velocity target vector from the network’s displacement predictions. The measured data, comprising sparse displacement response on the rod structure, are used to train the PINN. The wave velocity at the sparse locations on the rod is learned from the predicted displacements during the training. Using the predictions of the trained network, the response of free vibration or material property variation can be reconstructed at unscanned locations on the structure to obtain high-resolution maps for full-field imaging to detect and localize the changes caused by plastic deformation. The PINN’s sparse scanning and simultaneous prediction capability during training can lead to high scanning and data-processing speeds. This capability yields a nondestructive evaluation system that can predict the presence of degraded material locations as the structural vibrations are scanned and processed in real time.

Rathod, Vivek↗
DOE OSTI2013

Effects of tubulin acetylation and tubulin acetyltransferase binding on microtubule structure

Tubulin undergoes posttranslational modifications proposed to specify microtubule subpopulations for particular functions. Most of these modifications occur on the C-termini of tubulin and may directly affect the binding of microtubule-associated proteins (MAPs) or motors. Acetylation of Lys-40 on α-tubulin is unique in that it is located on the luminal surface of microtubules, away from the interaction sites of most MAPs and motors. We investigate whether acetylation alters the architecture of microtubules or the conformation of tubulin, using cryo–electron microscopy (cryo-EM). No significant changes are observed based on protofilament distributions or microtubule helical lattice parameters. Furthermore, no clear differences in tubulin structure are detected between cryo-EM reconstructions of maximally deacetylated or acetylated microtubules. Our results indicate that the effect of acetylation must be highly localized and affect interaction with proteins that bind directly to the lumen of the microtubule. We also investigate the interaction of the tubulin acetyltransferase, αTAT1, with microtubules and find that αTAT1 is able to interact with the outside of the microtubule, at least partly through the tubulin C-termini. Binding to the outside surface of the microtubule could facilitate access of αTAT1 to its luminal site of action if microtubules undergo lateral opening between protofilaments.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2021

LiDAR-Inertial Based Navigation and Mapping for Precision Landing

Future lander missions will travel to ambitious, scientifically interesting locations near rough and dangerous terrain. They will need to operate with limited prior information about the terrain, and under varying lighting conditions. Landing safely and precisely in the face of these challenges is difficult for existing vision-based landing systems, which require detailed orbital reconnaissance, a priori hazard maps, and impose time-of-day restrictions on landing to ensure similar lighting conditions in orbital and descent imagery. Advanced 3D imaging LiDAR systems currently under development, and originally intended for single-scan hazard detection, have the potential to be operated continuously from altitudes of up to 5 km. Used together with existing inertial measurement units (IMUs), these sensors open a path-to-flight for a full navigation and mapping system, which could replace or augment a traditional landing sensor suite. A landing system based around these sensors can perform accurate altimetry, map-relative localization (MRL), LiDAR-inertial odometry, and map refinement in an illumination-insensitive manner, over unknown or partially known terrain. This paper outlines preliminary work on a LiDAR-inertial landing system that: estimates the spacecraft trajectory during entry, descent, and landing (EDL); and maps the topography of the terrain below, for future use in hazard detection and avoidance. An incremental, factor graph based, smoothing approach is used to solve for the maximum a posteriori trajectory of spacecraft states. Integrated IMU measurements and features tracked in adjacent range and intensity images are used to estimate motion (LiDAR-inertial odometry). LiDAR scans are binned into motion-corrected digital elevation models (DEMs), which are matched to an existing orbital topographic map to provide absolute position information (MRL). The estimated trajectory is then used to project the LiDAR scans into the map frame, creating a variable-resolution quadtree topographic map suitable for hazard detection and avoidance. Existing topographic maps from throughout the solar system (i.e., Earth, the Moon, Mars, Ceres, Vesta, Europa, Enceladus, and Eros) are upsampled for use in EDL simulations. The Mars 2020 Lander Vision System Simulator (LVSS) is extended to simulate LiDAR-inertial data for realistic EDL trajectories. Results of the algorithm operating on the simulated data are presented. Estimated spacecraft trajectory and refined map are compared to ground truth to assess estimation accuracy.

Katake, Anup↗
NASA NTRS2017

Early Season Large-Area Winter Crop Mapping Using MODIS NDVI Data, Growing Degree Days Information and a Gaussian Mixture Model

Knowledge on geographical location and distribution of crops at global, national and regional scales is an extremely valuable source of information applications. Traditional approaches to crop mapping using remote sensing data rely heavily on reference or ground truth data in order to train/calibrate classification models. As a rule, such models are only applicable to a single vegetation season and should be recalibrated to be applicable for other seasons. This paper addresses the problem of early season large-area winter crop mapping using Moderate Resolution Imaging Spectroradiometer (MODIS) derived Normalized Difference Vegetation Index (NDVI) time-series and growing degree days (GDD) information derived from the Modern-Era Retrospective analysis for Research and Applications (MERRA-2) product. The model is based on the assumption that winter crops have developed biomass during early spring while other crops (spring and summer) have no biomass. As winter crop development is temporally and spatially non-uniform due to the presence of different agro-climatic zones, we use GDD to account for such discrepancies. A Gaussian mixture model (GMM) is applied to discriminate winter crops from other crops (spring and summer). The proposed method has the following advantages: low input data requirements, robustness, applicability to global scale application and can provide winter crop maps 1.5-2 months before harvest. The model is applied to two study regions, the State of Kansas in the US and Ukraine, and for multiple seasons (2001-2014). Validation using the US Department of Agriculture (USDA) Crop Data Layer (CDL) for Kansas and ground measurements for Ukraine shows that accuracies of greater than 90% can be achieved in mapping winter crops 1.5-2 months before harvest. Results also show good correspondence to official statistics with average coefficients of determination R(exp. 2) greater than 0.85.

mixture model↗
DOE OSTI2019

Thermally Conductive Backsheets (TCB) for Reduced Operating Temperatures

The performance of photovoltaic (PV) modules is primarily influenced by the plane of array (POA) irradiance and their operating temperature. The lower the module operating temperature, the higher is its performance. Increasing a module’s operating temperature reduces its power output due to an increase in the semiconductor’s intrinsic carrier density, leading to a reduction in the open-circuit voltage and, subsequently, reducing the maximum power point voltage. Reducing the operating temperature lowers the levelized cost of energy (LCOE) via increased energy production (i.e., more kilowatt hour over the life of the asset) and increased service lifetime (years in the field). The module operating temperature is dictated by the weather parameters and the thermal properties of module construction materials. The primary weather parameters influencing the PV module temperature are: the ambient temperature (directly related), irradiance (directly related), and wind speed (inversely related). The primary thermal properties of module construction materials influencing the PV module temperature are: the optical transmissivity and thermal conductivity of superstrate, the thermal conductivity of substrate, the thermal conductivity of encapsulant and the efficiency of the encapsulated solar cells. The primary goal of this study is to reduce the operating temperature of PV modules using thermally conductive backsheet (TCB) substrates developed by the industry. The temperature of PV modules installed in a large multi-MW plant can also be influenced by their physical locations in the plants due to the influence of wind direction. A thermal mapping of PV plants has also been investigated and presented in this study. The most commonly used PV backsheet material has been polyvinyl fluoride (DuPont trade name “Tedlar”)-based backsheet, which typically has three layers: Tedlar–polyethylene terephthalate (PET)–Tedlar (TPT). The primary goal of this project is to reduce the module operating temperature below the benchmark TPT backsheet temperature using newly developed TCBs by the industry. The overall approach of this project involves six focus areas: i) select and procure one TPT and thirteen promising TCBs available in the industry; ii) construct a large number of 1-cell and 9-cell modules using benchmark TPT and selected TCBs [all other construction materials are fixed and they are: glass superstrate, EVA encapsulant, mono-Si cell and junction box]; iii) to identify best performing TCBs, monitor the long-term field operating temperatures of the constructed modules which are installed in three climatic conditions (hot-low wind [Mesa, AZ], hot-high wind [Maricopa County, AZ] and temperate [Cumberland County, NC]; iv) to identify the most durable TCB, perform extended accelerated reliability testing of modules constructed with best three TCBs and benchmark TPT; v) to predict module temperature, develop physical and empirical thermal models with and without thermal properties of all construction materials in the modules, respectively; and vi) to determine the influence of wind speed and direction on the module operating temperature in a plant, and perform thermal mapping of PV modules in two large PV plants [Maricopa County, AZ and Cumberland County, NC]. The key achievements of this project are listed below: Backsheet selection: 14 backsheets were procured after an extensive literature and industry search. Finally, based on the thermal and other selection criteria, 1 TPT and 4 thermally conductive backsheets were selected for this project. Fabrication of mini modules: 50 one-cell modules were fabricated in year 1 for thermal performance evaluation. The module design was changed to nine-cell module at start of year 2 to mimic commercial design. 20 nine-cell modules were fabricated in year 2 for thermal performance evaluation. 28 four-cell modules were fabricated in year 3 for accelerated stress-testing. Thermal conductivity of backsheets: Year 1 TCBs showed at least 8% higher thermal conductivities than TPT. Year 2 and 3 TCBs showed at least 20% higher thermal conductivities than TPT. Installation of mini PV modules at three sites: 6 one-cell modules and 8 nine-cell modules were installed at AZ-1 site [Mesa, AZ]. 12 one-cell modules and 6 nine-cell modules were installed at each of two powerplants (AZ-2 [Maricopa County, AZ] and NC sites). Nominal operating cell temperatures (NOCT) of mini PV modules: NOCT of TCBs were observed to be lower than TPT with differences as high as 2°C. Comparison of thermal performance: The median operating temperature of one-cell modules was found to be reduced by 2°C by using TCB_A modules compared to TPT modules on several days in a month for few months in a year. The median temperature improvement of 4oC was achieved at several instances on a few days, but not all days, in a year using multiple TCBs compared to TPT. The final project milestone of achieving median temperature improvement of 5oC was achieved at several instances on a few days, but not all days, in a year using TCB_A compared to TPT. Empirical thermal model (without the need of construction material properties): Empirical thermal model for one-cell module was developed based on the input data of irradiance, wind speed and ambient temperatures. The primary input data differentiator for temperature differences between TPT and TCBs appears to be the irradiance level (solar gain). Accelerated durability testing: 20 four-cell modules using 4 backsheets (1 TPT and 3 TCBs) were exposed to Damp Heat 1000 hours (8 modules), UV/Thermal cycling (50 cycles)/Humidity freeze (10 cycles) test sequence (8 modules) and UV Weathering for qualification (8 modules). All the modules with four selected backsheets passed the stress tests per the retest guidelines of IEC 61215 standard for the backsheet change. Simplified comparative LCOE analysis: Using backsheet-specific power degradation levels in the accelerated tests (for TCB_A and TPT only), efficiency, service lifetime and assuming same cost for all backsheets, the LCOE of modules using TCB_A is determined to be lower than TPT. Due to lower operating temperature of TCB_A-based modules compared to TPT-based modules, the operating efficiency and service life of TCB_A-based modules are calculated to be higher than TPT-based modules. Temperature mapping of PV power plants: A distinct temperature difference (as high as 4°C) has been observed between the modules located in various parts of a single PV plant.

14 SOLAR ENERGY↗
NASA NTRS1993

The cartography of Venus with Magellan data

Maps of Venus based on Magellan data are being compiled at 1:50,000,000, 1:5,000,000 and 1:1,500,000 scales. Topographic contour lines based on radar altimetry data are overprinted on the image maps, along with feature nomenclature. Map controls are based on existing knowledge of the spacecraft orbit; photogrammetric triangulation, a traditional basis for geodetic control for bodies where framing cameras were used, is not feasible with the radar images of Venus. Preliminary synthetic aperture radar (SAR) image maps have some data gaps and cosmetic inconsistencies, which will be corrected on final compilations. Eventual revision of geodetic controls and of the adopted Venusian spin-axis location will result in geometric adjustments, particularly on large-scale maps.

Kirk, R. L.↗
DOE OSTI2014

TU-C-17A-07: FusionARC Treatment with Adaptive Beam Selection Method

Purpose: Recently, a new treatment scheme, FusionARC, has been introduced to compensate for the pitfalls in single-arc VMAT planning. It basically allows for the static field treatment in selected locations, while the remaining is treated by single-rotational arc delivery. The important issue is how to choose the directions for static field treatment. This study presents an adaptive beam selection method to formulate fusionARC treatment scheme. Methods: The optimal plan for single-rotational arc treatment is obtained from two-step approach based on the reweighted total-variation (TV) minimization. To choose the directions for static field treatment with extra segments, a value of our proposed cost function at each field is computed on the new fluence-map, which adds an extra segment to the designated field location only. The cost function is defined as a summation of equivalent uniform dose (EUD) of all structures with the fluence-map, while assuming that the lower cost function value implies the enhancement of plan quality. Finally, the extra segments for static field treatment would be added to the selected directions with low cost function values. A prostate patient data was applied and evaluated with three different plans: conventional VMAT, fusionARC, and static IMRT. Results: The 7 field locations, corresponding to the lowest cost function values, are chosen to insert extra segment for step-and-shoot dose delivery. Our proposed fusionARC plan with the selected angles improves the dose sparing to the critical organs, relative to static IMRT and conventional VMAT plans. The dose conformity to the target is significantly enhanced at the small expense of treatment time, compared with VMAT plan. Its estimated treatment time, however, is still much faster than IMRT. Conclusion: The fusionARC treatment with adaptive beam selection method could improve the plan quality with insignificant damage in the treatment time, relative to the conventional VMAT.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Asia-Pacific water-energy dependence mapped in Sandia study

A wide-ranging analysis of water vulnerability across the Pacific — including the U.S., China, Russia and Japan — has identified hundreds of locations where energy production depends upon scarce water supplies. The Sandia National Laboratories study, Mapping Water Consumption for Energy Production Around the Pacific Rim, was published in Environmental Research Letters. Prepared for the Asia-Pacific Economic Corporation (APEC), the first-of-its-kind report maps out every power plant, refinery and mine in 21 Asian-Pacific economies that rely on fresh water for energy. Simultaneously, it shows the data in context to regions at high to extreme risk of drought and dwindling natural water supplies.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1992

Determining the source region of auroral emissions in the prenoon oval using coordinated Polar BEAR UV-imaging and DMSP particle measurements

The Polar Beacon Experiment and Auroral Research (Polar BEAR) satellite included the capability for imaging the dayside auroral oval in full sunlight at several wavelengths. Particle observations from the DMSP F7 satellite during dayside auroral oval crossings are compared with approximately simultaneous Polar BEAR 1356-A images to determine the magnetospheric source region of the dayside auroral oval. The source region is determined from the DMSP particle data, according to recent work concerning the classification and identification of precipitation source regions. The close DMSP/Polar BEAR coincidences all occur when the former satellite is located between 0945 and 1000 MLT. Instances of auroral arcs mapping to each of several different regions, including the boundary plasma sheet, the low-latitude boundary layer, and the plasma mantle were found. It was determined that about half the time the most prominent auroral arcs are located at the interfaces between distinct plasma regions, at least at the local time studied here.

Newell, Patrick T.↗
NASA NTRS2002

Scanning Electron Microscope Mapping System Developed for Detecting Surface Defects in Fatigue Specimens

An automated two-degree-of-freedom specimen positioning stage has been developed at the NASA Glenn Research Center to map and monitor defects in fatigue specimens. This system expedites the examination of the entire gauge section of fatigue specimens so that defects can be found using scanning electron microscopy (SEM). Translation and rotation stages are driven by microprocessor-based controllers that are, in turn, interfaced to a computer running custom-designed software. This system is currently being used to find and record the location of ceramic inclusions in powder metallurgy materials. The mapped inclusions are periodically examined during interrupted fatigue experiments. The number of cycles to initiate cracks from these inclusions and the rate of growth of initiated cracks can then be quantified. This information is necessary to quantify the effect of this type of defect on the durability of powder metallurgy materials. This system was developed with support of the Ultra Safe program.

Bonacuse, Peter J.↗