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At least 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Evidence for the Sequestration of Hydrogen-Bearing Volatiles Towards the Moons Southern Pole-Facing Slopes

The Lunar Exploration Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter (LRO) detects a widespread suppression of the epithermal neutron leakage flux that is coincident with the pole-facing slopes (PFS) of the Moon's southern hemisphere. Suppression of the epithermal neutron flux is consistent with an interpretation of enhanced concentrations of hydrogen-bearing volatiles within the upper meter of the regolith. Localized flux suppression in PFS suggests that the reduced solar irradiation and lowered temperature on PFS constrains volatility to a greater extent than in surrounding regions. Epithermal neutron flux mapped with LEND's Collimated Sensor for Epithermal Neutrons (CSETN) was analyzed as a function of slope geomorphology derived from the Lunar Orbiting Laser Altimeter (LOLA) and the results compared to co-registered maps of diurnally averaged temperature from the Diviner Lunar Radiometer Experiment and an averaged illumination map derived from LOLA. The suppression in the average south polar epithermal neutron flux on equator-facing slopes (EFS) and PFS (85-90 deg S) is 3.3 +/- 0.04% and 4.3 +/- 0.05% respectively (one-sigma-uncertainties), relative to the average count-rate in the latitude band 45-90 deg S. The discrepancy of 1.0 +/- 0.06% between EFS and PFS neutron flux corresponds to an average of approximately 23 parts-per-million-by-weight (ppmw) more hydrogen on PFS than on EFS. Results show that the detection of hydrogen concentrations on PFS is dependent on their spatial scale. Epithermal flux suppression on large scale PFS was found to be enhanced to 5.2 +/- 0.13%, a discrepancy of approximately 45 ppmw hydrogen relative to equivalent EFS. Enhanced poleward hydration of PFS begins between 50 deg S and 60 deg S latitude. Polar regolith temperature contrasts do not explain the suppression of epithermal neutrons on pole-facing slopes. The Supplemental on-line materials include supporting results derived from the uncollimated Lunar Prospector Neutron Spectrometer and the LEND Sensor for Epithermal Neutrons.

Ices↗
NASA NTRS2018

UTM UAS Serivce Supplier Development: Sprint 1 Toward Technical Capability Level 4

NASA's UAS Traffic Management (UTM) Project has been tasked with developing concepts and initial implementations for integrating and managing small unmanned aircraft systems (UAS) into the low altitude airspace. To accomplish this task, the Project planned a phased approach based on four Technical Capability Levels (TCLs). As of this writing, TCL4 is currently in development for a late Spring 2019 flight demonstration. This TCL is focused on operations in an urban environment and includes the handling of high density and large-scale off-nominal conditions, vehicle-to-vehicle communications, detect-and-avoid technologies, communication requirements, public safety operations, airspace restrictions, and other related goals. Through research and testing to date, NASA has developed an architecture for UTM that depends on commercial entities collaboratively providing services that are traditionally provided by the Air Navigation Service Provider(ANSP) in manned aviation. A key component of this architecture is the UAS Service Supplier (USS), which acts as a communications bridge between UAS operators and the ANSP when necessary. In addition, the collection of USSs form a USS Network to collaboratively manage the airspace through the sharing of data and the adherence to a standard or set of standards required to participate in this USS Network. This document provides a record of the first step in the development of interoperable USSs that will ultimately support TCL4 flight testing and formalization of the overall UTM concept. To develop these USSs and the underlying specifications for them, NASA has planned a series of "Sprints" to work with industry partners in implementing the features and proposed specifications for USSs to participate in TCL4. This report describes Sprint One. In this Sprint, the focus was on establishing a baseline for the Application Programming Interfaces (APIs) and their associated data models. In addition, the concept of UAS Volume Reservations (UVR) (areas that impose restrictions on sUAS that are allowed to operate) was tested. NASA provided the specifications and iterated on them with partners while implementers developed to those specifications. NASA then tested each partner's implementation to ensure compatibility with all other implementers. This process helped all stakeholders gain confidence that the foundation for future Sprints was solid.

UAS service supplier↗
NASA NTRS2018

UTM UAS Service Supplier Development: Sprint 2 Toward Technical Capability Level 4

NASA's UAS Traffic Management (UTM) Project has been tasked with developing concepts and initial implementations for integrating and managing small unmanned aircraft systems (UAS) into the low altitude airspace. To accomplish this task, the UTM Project planned a phased approach based on four Technical Capability Levels (TCLs). As of this writing, TCL4 is currently in development for a late Spring 2019 flight demonstration. This TCL is focused on operations in an urban environment and includes the handling of high density environments, large-scale off-nominal conditions, vehicle-to-vehicle communications, detect-and-avoid technologies, communication requirements, public safety operations, airspace restrictions, and other related goals. Through research and testing to date, NASA has developed an architecture for UTM that depends on commercial entities collaboratively providing services that are traditionally provided by the Air Navigation Service Provider (ANSP) in manned aviation. A key component of this architecture is the UAS Service Supplier (USS), which acts as a communications bridge between UAS operators and the ANSP when necessary. In addition, the collection of USSs form a USS Network to collaboratively manage the airspace through the sharing of data and the adherence to a standard or set of standards required to participate in this USS Network. This document provides a record of the second of four planned steps in the development of interoperable USSs that will ultimately support TCL4 flight testing and formalization of the overall UTM concept. To develop these USSs and their underlying specifications, NASA has planned a series of "Sprints" to work with industry partners in implementing the features and develop proposed specifications for USSs in order to to participate in TCL4. This report describes Sprint Two. In this Sprint, there was a major theme with four goals. The theme was the development and testing of a new USS discovery system, to better enable USSs to find and communicate with each other. The goals supporting this theme were: participants needed to implement and exercise the discovery service for USS-USS communications; USSs needed to demonstrate strategic deconfliction through operation sharing; the systems were to use discovery to aid in handling off-nominal operations; and finally, there was an investigation of an initial off-nominal reporting capability.

software engineering↗
NASA NTRS2022

Desert Locust Cropland Damage Differentiated from Drought, with Multi-Source Remote Sensing in Ethiopia

In 2020, Ethiopia had the worst desert locust outbreak in 25 years, leading to food insecurity. Locust research has typically focused on predicting the paths and breeding grounds based on ground surveys and remote sensing of outbreak factors. In this study, we hypothesized that it is possible to detect desert locust cropland damage through the analysis of fine-scale (5–10 m) resolution satellite remote sensing datasets. We performed our analysis on 121 swarm point locations on croplands derived from the Food and Agriculture Organization (FAO) of the United Nations, and 94 ‘non-affected’ random cropland sample points generated for this study that are distributed within 20–25 km from the ‘center’ of swarm affected sample locations. Integrated Drought Condition Indices (IDCIs) and Vegetation Health Indices (VHIs) calculated for the affected sample locations for 2000–2020 were strongly correlated (R(exp 2) > 0.90) with that of the corresponding non-affected group of sample sites. Drought indices were strongly correlated with the evaluation Standardized Precipitation Evapotranspiration Indices (SPEIs) and showed that 2020 was the wettest year since 2000. In 2020, the NDVI and backscatter coefficient of cropland phenologies from the affected versus non-affected cropland sample sites showed a slightly wider, but significant gap in March (short growing season) and August-October (long growing season). Thus, slightly wider gaps in cropland phenologies between the affected and non-affected sites were likely induced from the locust damage, not drought, with fine scale data representing a larger gap.

Desert locust↗
NASA NTRSDate not supplied

Sampling of Space-Based Observations of XCO2 Associated With Biomass Burning Events

- The OCO-2 Level 3 assimilation product fills in gaps where OCO-2 does not have observations. - Although the Level 3 clearly shows the increased CO2 over the Amazon associated with the September 2017 biomass burning event, the total amount of CO2 may be underestimated because of a sampling bias. - The TCCON observations match fairly well with the OCO-2 observations and can be used to estimate the accuracy of the OCO observations and the temporal sampling bias. However, since it is a remotely sensed product, it may suffer the same sampling biases associated with biomass burning events as OCO-2. - Although aircraft data show that there is a significant variation in xCO2 with altitude, they suggest the OCO-2 fused products created by kriging may be better than the assimilated product at detecting large deviations from the average state on daily and regional scales.

Thomas J. Hearty, III↗
NASA NTRSDate not supplied

The LuNaMaps Project: Advancing Capabilities for Developing and Validating Digital Elevation Models of Rocky Surfaces from Orbital Data

Both navigation and surface science can benefit from the ability to generate high resolution and accurate maps of the surface of the Moon and other solar system bodies. The primary way these maps are generated is through the use of orbital imagery and ranging data. Traditionally, the process of using orbital imagery and ranging data is tedious and labor-intensive. Additionally, once maps have been built, there has generally been limited effort in developing standards by which to verify the accuracy and quality of the generated maps. The Lunar Navigation Maps (LuNaMaps) project is a NASA Game Changing Development (GCD) project which over the last 4 years has aimed to address these issues both for the Moon and for other rocky solar system bodies. This has been accomplished through development of new and existing capabilities including: a suite of methods and tools to combine all sources of orbital imagery; a benchmark data set as well as basic requirements for high-fidelity simulations of precision landing functions; tools to synthetically enhance map products with lander-scale features for use in the development and testing of hazard detection systems; methods and tools to evaluate the accuracy of developed digital elevation maps (DEMs) and their quality for use in terrain relative navigation scenarios; and tools to realistically render image and lidar data. In this work, we provide an overview of the capabilities developed through LuNaMaps, demonstrating its use for processing existing lunar data, and describing how it can be applied to other use cases. We additionally provide preliminary results showing the application of the developed tools and processes to the generation of elevation maps of the Lunar Surface Proving Grounds (LSPG) lunar analog at Astrobotic’s Mojave testing facility using “orbital imagery” captured by a drone. In this terrestrial demonstration, we have the benefit of being able to compare the results to a ground truth model of the LSPG. We finally describe plans to use the newly created maps in a terrestrial terrain relative navigation demonstration over the LSPG in early 2025.

optical navigation↗
DOE OSTI2014

Molecular cloud-scale star formation in NGC 300

We present the results of a galaxy-wide study of molecular gas and star formation in a sample of 76 H II regions in the nearby spiral galaxy NGC 300. We have measured the molecular gas at 250 pc scales using pointed CO(J = 2-1) observations with the Atacama Pathfinder Experiment telescope. We detect CO in 42 of our targets, deriving molecular gas masses ranging from our sensitivity limit of ∼10{sup 5} M {sub ☉} to 7 × 10{sup 5} M {sub ☉}. We find a clear decline in the CO detection rate with galactocentric distance, which we attribute primarily to the decreasing radial metallicity gradient in NGC 300. We combine Galaxy Evolution Explorer far-ultraviolet, Spitzer 24 μm, and Hα narrowband imaging to measure the star formation activity in our sample. We have developed a new direct modeling approach for computing star formation rates (SFRs) that utilizes these data and population synthesis models to derive the masses and ages of the young stellar clusters associated with each of our H II region targets. We find a characteristic gas depletion time of 230 Myr at 250 pc scales in NGC 300, more similar to the results obtained for Milky Way giant molecular clouds than the longer (>2 Gyr) global depletion times derived for entire galaxies and kiloparsec-sized regions within them. This difference is partially due to the fact that our study accounts for only the gas and stars within the youngest star-forming regions. We also note a large scatter in the NGC 300 SFR-molecular gas mass scaling relation that is furthermore consistent with the Milky Way cloud results. This scatter likely represents real differences in giant molecular cloud physical properties such as the dense gas fraction.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Wafer-scale metasurface for total power absorption, local field enhancement and single molecule Raman spectroscopy

The ability to detect molecules at low concentrations is highly desired for applications that range from basic science to healthcare. Considerable interest also exists for ultrathin materials with high optical absorption, e.g. for microbolometers and thermal emitters. Metal nanostructures present opportunities to achieve both purposes. Metal nanoparticles can generate gigantic field enhancements, sufficient for the Raman spectroscopy of single molecules. Thin layers containing metal nanostructures (‘‘metasurfaces’’) can achieve near-total power absorption at visible and near-infrared wavelengths. Thus far, however, both aims (i.e. single molecule Raman and total power absorption) have only been achieved using metal nanostructures produced by techniques (high resolution lithography or colloidal synthesis) that are complex and/or difficult to implement over large areas. Here, we demonstrate a metasurface that achieves the near-perfect absorption of visible-wavelength light and enables the Raman spectroscopy of single molecules. Our metasurface is fabricated using thin film depositions, and is of unprecedented (wafer-scale) extent.

NANOPARTICLES↗
NASA NTRS1999

A Mode Detection Method Using the Azimuthal Directivity of a Turbofan Model

The azimuthal, far field directivity of a scale fan model was measured in high resolution. The model is a 12 inch diameter rotor with 16 blades followed by 40 stator vanes. The tests were conducted at the nominal 100% speed corresponding to a tip speed of 905 ft/sec. Measurement of the radiated sound field, forward of the fan, was made in an anechoic chamber with an inflow control device and a baffle separating the aft and forward radiated interaction noise. The acoustic field was surveyed with a circular hoop array of 16 microphones which was moved to 14 axial stations. At each axial station the hoop was rotated in half-degree increments to take 736 points in the azimuthal angle. In addition to sound pressure level, the phase angle relative to a reference microphone was measured at each point. The sound pressure level is shown to vary in patterns by 10-15 dB especially for the fundamental tone but also for the first and second harmonic. A far field mode detection method has been developed and used with the data which determines the modes generated by the fan and which then interact to form the azimuthal directivity.

Thomas, R. H.↗
DOE OSTI2022

Ultrafast laser filament-induced fluorescence for detecting uranium stress in Chlamydomonas reinhardtii

Abstract Plants and other photosynthetic organisms have been suggested as potential pervasive biosensors for nuclear nonproliferation monitoring. We demonstrate that ultrafast laser filament-induced fluorescence of chlorophyll in the green alga Chlamydomonas reinhardtii is a promising method for remote, in-field detection of stress from exposure to nuclear materials. This method holds an advantage over broad-area surveillance, such as solar-induced fluorescence monitoring, when targeting excitation of a specific plant would improve the detectability, for example when local biota density is low. After exposing C. reinhardtii to uranium, we find that the concentration of chlorophyll a, chlorophyll fluorescence lifetime, and carotenoid content increase. The increased fluorescence lifetime signifies a decrease in non-photochemical quenching. The simultaneous increase in carotenoid content implies oxidative stress, further confirmed by the production of radical oxygen species evidence in the steady-state absorption spectrum. This is potentially a unique signature of uranium, as previous work finds that heavy metal stress generally increases non-photochemical quenching. We identify the temporal profile of the chlorophyll fluorescence to be a distinguishing feature between uranium-exposed and unexposed algae. Discrimination of uranium-exposed samples is possible at a distance of $$\sim $$ ∼ 35 m with a single laser shot and a modest collection system, as determined through a combination of experiment and simulation of distance-scaled uncertainty in discriminating the temporal profiles. Illustrating the potential for remote detection, detection over 125 m would require 100 laser shots, commensurate with the detection time on the order of 1 s.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

DETECTING FIRE WITH MACHINE LEARNING-ENABLED VISUAL MONITORING FOR NUCLEAR POWER PLANT ENVIRONMENTS

Nuclear power plants are experiencing significant cost challenges to remain competitive with other energy-generation utilities. Unlike other industries, the cost of operation and maintenance activities is mostly attributed to workforce costs. To mitigate this, nuclear power plant stakeholders are increasingly interested in the development and deployment of machine learning methods to potentially automate or augment manually intensive tasks to reduce costs, especially for monitoring activities. One monitoring function that is visually demanding and that can occur frequently to meet the requirements of a fire protection program is visually monitoring an area for fire occurrence. Currently, fire watch activities consist of a worker physically stationed at a given location with the sole responsibility of observing a given area to ensure a fire is detected and mitigated promptly. This effort focused on the development and evaluation of a suitable deep convolutional neural network to classify individual video frames at a sub-second frequency for the occurrence of “fire” and “no fire” in varying industrial environments similar to nuclear power plants. It is believed that a trained neural network model could be integrated with existing facility video surveillance camera feeds to generate alerts when fire inferences occur in individual frames captured at sub-second temporal resolutions. Extensive effort was dedicated to identifying and curating suitable imagery training data representing varying environments and scene settings with and without flame features to maximize generalization in nuclear power plant environments. The data collection effort resulted in the aggregation of a large, labeled image library exceeding 12,000 images to support model training for diverse industrial environments. A deep neural network model incorporating parallel multi-scale capabilities was developed and trained to support accurate image-based detection of flame incidents of varying sizes and spectral feature properties within heterogeneous scenes. Analysis results show that the trained model can achieve high inference accuracy despite heterogeneous scene environments and components. Testing accuracy exceeded 95.0 percent with very low false positive and false negative inferences.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

GROUND-BASED TRANSIT SPECTROSCOPY OF THE HOT-JUPITER WASP-19b IN THE NEAR-INFRARED

We present ground-based measurements of the transmission and emission spectra of the hot-Jupiter WASP-19b in nine spectroscopic channels from 1.25 to 2.35 {mu}m. The measurements are based on the combined analysis of time-series spectroscopy obtained during two complete transits and two complete secondary eclipses of the planet. The observations were performed with the MMIRS instrument on the Magellan II telescope using the technique of multi-object spectroscopy with wide slits. We compare the transmission and emission data to theoretical models to constrain the composition and thermal structure of the planet's atmosphere. Our measured transmission spectrum exhibits a scatter that corresponds to 1.3 scale heights of the planet's atmosphere, which is consistent with the size of spectral features predicted by theoretical models for a clear atmosphere. We detect the secondary eclipses of the planet at significances ranging from 2.2{sigma} to 14.4{sigma}. The secondary eclipse depths, and the significances of the detections increase toward longer wavelengths. Our measured emission spectrum is consistent with a 2250 K effectively isothermal one-dimensional model for the planet's dayside atmosphere. This model also matches previously published photometric measurements from the Spitzer Space Telescope and ground-based telescopes. These results demonstrate the important role that ground-based observations using multi-object spectroscopy can play in constraining the properties of exoplanet atmospheres, and they also emphasize the need for high-precision measurements based on observations of multiple transits and eclipses.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1999

Microscopy of Analogs for Martian Dust and Soil

The upcoming Mars 2001 lander will carry an atomic force microscope (AFM) as part of the Mars Environmental Compatibility Assessment (MECA) payload. By operating in a tapping mode, the AFM is capable of sub-nanometer resolution in three dimensions and can distinguish between substances of different compositions by employing phase-contrast imaging. Phase imaging is an extension of tapping-mode AFM that provides nanometer-scale information about surface composition not revealed in the topography. Phase imaging maps the phase of the cantilever oscillation during the tapping mode scan, hence detecting variations in composition, adhesion, friction, and viscoelasticity. Because phase imaging highlights edges and is not affected by large-scale height differences, it provides for clearer observation of fine features, such as grain edges, which can be obscured by rough topography. To prepare for the Mars 01 mission, we are testing the AFM on a lunar soil and terrestrial basaltic glasses to determine the AFMOs ability to define particle shapes and sizes and grain-surface textures. The test materials include the Apollo 17 soil 79221, which is a mixture of agglutinates, impact and volcanic beads, and mare and highland rock and mineral fragments. The majority of the lunar soil particles are less than 100 microns in size, comparable to the sizes estimated for Martian dust. The terrestrial samples are millimeter size basaltic glasses collected on Black Pointe at Mono Lake, just north of the Long Valley caldera in California. The basaltic glass formed by a phreatomagmatic eruption 13,000 years ago beneath a glacier that covered the Mono Lake region. Because basaltic glass formed by reworking of pyroclastic deposits may represent a likely source for Martian dunes, these basaltic glass samples represent plausible analogs to the types of particles that may be studied in sand dunes by the 01 lander and rover. We have used the AFM to examine several different soil particles at various resolutions. The instrument has demonstrated the ability to identify parallel ridges characteristic of twinning on a 150-micron plagioclase feldspar particle. Extremely small (10-100 nanometer) adhering particles are visible on the surface of the feldspar grain, and appear elongate with smooth surfaces. Phase contrast imaging of the nanometer particles shows several compositions to be present. When the AFM was applied to a 100-micron glass spherule, it was possible to define an extremely smooth surface.E Also visible on the surface of the glass spherule were chains of 100-nanometer- and-smaller impact melt droplets. Additional information is contained in the original extended abstract.

Anderson, M. A.↗
NASA NTRS1983

General circulation and the dynamical state of the Venus atmosphere

The principal mode of atmospheric circulation on Venus is a zonal retrograde superrotation of the entire atmosphere, from the lowest scale height to altitudes of more than 100 km, with an angular momentum that is about 0.15 percent of the solid planet angular momentum. These values suggest the possibility of significant angular momentum exchanges between the two reservoirs, yielding day length changes that may be of the order of hours and could therefore be detected by earth-based radar. Eddies, the mean meridional circulation, and planetary-scale waves may all be involved in the upward transport of retrograde angular momentum to maintain atmospheric counterrotation. Eddies have been observed in the lower atmoshere and may also transport heat and momentum latitudinally and vertically. Waves are present throughout the atmosphere, over a wide range of spatial scales. The mean zonal and meridional circulations may not be symmetric about the equator.

Schubert, G.↗
DOE OSTI2020

Simulation and Development of the Radial Time Projection Chamber For the Bonus12 Experiment in CLAS12

Knowledge of the structure of nucleons (i.e. protons and neutrons) is a central topic of interest to nuclear/particle physicists. Much more is known about the structure of the proton than the neutron due to the lack of high-density free neutron targets. The Barely Off-shell Nucleon Structure experiment (BONuS12) at Jefferson Lab (JLab) is a second generation experiment upgraded/optimized to advance our knowledge of the neutron's structure using the deep-inelastic scattering of electrons off deuterium. Typically, since deuterium is a nuclear target, corrections for off-shell and nuclear binding effects must be taken into account in order to extract results on the neutron. These corrections are model-dependent and therefore have limited our success in extracting neutron information using deuterium targets. In the BONuS12 experiment, 10.6 GeV electrons are scattered off of a deuterium target. By detecting the low momentum spectator proton at backward angles, the uncertainty due to final state interactions is minimized. The goal of the experiment is to measure the ratio of the neutron to proton structure functions ($F^n_2/F^p_2$) as the Bjroken scaling variable x approaches 1. The newly designed Radial Time Projection Chamber (RTPC) for BONuS12 detects the spectator proton in coincidence with the scattered electron, which is detected in the CEBAF Large Acceptance Spectrometer (CLAS12). This work presents the simulation and development of the new BONuS12 RTPC. The design, construction, and testing of the Drift-gas Monitoring Sysytem (DMS) for the BONuS12 experiment is also described. The results of the DMS operation as well as the first preliminary data from the BONuS12 experimental run are given. Because the BONuS12 data analysis depends on CLAS12 working effectively, an effort to verify the CLAS12 operation with the extraction of the inclusive deep inelastic cross section from the first experiment in CLAS12 (Run Group A) will be presented.

Dzbenski, Nathan↗
DOE OSTI2018

New Self-lensing Models of the Small Magellanic Cloud: Can Gravitational Microlensing Detect Extragalactic Exoplanets?

We use three-dimensional distributions of classical Cepheids and RR Lyrae stars in the Small Magellanic Cloud (SMC) to model the stellar density distribution of a young and old stellar population in that galaxy. We use these models to estimate the microlensing self-lensing optical depth to the SMC, which is in excellent agreement with the observations. Our models are consistent with the total stellar mass of the SMC of about 1.0×10{sup 9} M{sub ⊙} under the assumption that all microlensing events toward this galaxy are caused by self-lensing. We also calculate the expected event rates and estimate that future large-scale surveys, like the Large Synoptic Survey Telescope (LSST), will be able to detect up to a few dozen microlensing events in the SMC annually. If the planet frequency in the SMC is similar to that in the Milky Way, a few extragalactic planets can be detected over the course of the LSST survey, provided significant changes in the SMC observing strategy are devised. A relatively small investment of LSST resources can give us a unique probe of the population of extragalactic exoplanets.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Detecting anomalous packets in network transfers: investigations using PCA, autoencoder and isolation forest in TCP

Large-scale scientific workflows rely heavily on high-performance file transfers. These transfers require strict quality parameters such as guaranteed bandwidth, no packet loss or data duplication. To have successful file transfers, methods such as predetermined thresholds and statistical analysis need to be done to determine abnormal patterns. Network administrators routinely monitor and analyze network data for diagnosing and alleviating these, making decisions based on their experience. However, as networks grow and become complex, monitoring large data files and quickly processing them, makes it improbable to identify errors and rectify these. Abnormal file transfers have been classified by simply setting alert thresholds, via tools such as PerfSonar and TCP statistics (Tstat). This paper investigates the feasibility of unsupervised feature extraction methods for identifying network anomaly patterns with three unsupervised classification methods—principal component analysis, autoencoder and isolation forest. Here, we collect file transfer statistics from two experiment sets—synthetic iPerf generated traffic and 1000 Genome workflow runs, with synthetically introduced anomalies. Our results show that while PCA and a simple autoencoder finds it difficult to detect clusters, the tree-variant isolation forest is able to identify anomalous packets by breaking down TCP traces into tree classes early.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Prospects for detecting heavy WIMP dark matter with the Cherenkov Telescope Array: The Wino and Higgsino

TeV-scale particles that couple to the standard model through the weak force represent a compelling class of dark matter candidates. The search for such weakly interacting massive particles has already spanned multiple decades, and whilst it has yet to provide any definitive evidence for their existence, viable parameter space remains. In this paper, we show that the upcoming Cherenkov Telescope Array (CTA) has significant sensitivity to uncharted parameter space at the TeV mass scale. To do so, we focus on two prototypical dark matter candidates, the Wino and Higgsino. Additionally, sensitivity forecasts for both models are performed including the irreducible background from misidentified cosmic rays, as well as a range of estimates for the Galactic emissions at TeV energies. For each candidate, we find substantial expected improvements over existing bounds from current imaging atmospheric Cherenkov telescopes. In detail, for the Wino we find a sensitivity improvement of roughly an order of magnitude in <σ v>, whereas for the Higgsino we demonstrate that CTA has the potential to become the first experiment that has sensitivity to the thermal candidate. Taken together, these enhanced sensitivities demonstrate the discovery potential for dark matter at CTA in the 1–100 TeV mass range.

79 ASTRONOMY AND ASTROPHYSICS↗