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All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Networked HIL Simulation System for Modeling Large-scale Power Systems

This paper presents a network hardware-in-the-loop (HIL) simulation system for modeling large-scale power systems. Researchers have developed many HIL test systems for power systems in recent years. Those test systems can model both microsecond-level dynamic responses of power electronic systems and millisecond-level transients of transmission and distribution grids. By integrating individual HIL test systems into a network of HIL test systems, we can create large-scale power grid digital twins with flexible structures at required modeling resolution that fits for a wide range of system operating conditions. This will not only significantly reduce the need for field tests when developing new technologies but also greatly shorten the model development cycle. In this paper, we present a networked OPAL-RT based HIL test system for developing transmission-distribution coordinative Volt-VAR regulation technologies as an example to illustrate system setups, communication requirements among different HIL test systems, and connection mechanisms. Impacts of communication delays, information exchange cycles, and computing delays are illustrated. Simulation results show that the performance of a networked HIL test system is satisfactory.

digital twin, distribution system, co-simulation, ↗
NASA NTRS2001

The THOR Project-Reducing the Impact of Thunderstorms on Aviation and the General Public Through a Multi-Agency Effect

Thunderstorms are high impact weather phenomena. They also pose an extremely challenging forecast problem. The National Oceanic and Atmospheric Administration (NOAA), the Federal Aviation Administration (FAA), the National Aeronautic and Space Administration (NASA), and the Air Force Weather Agency (AFWA), have decided to pool technology and scientific expertise into an unprecedented effort to better observe, diagnose, and forecast thunderstorms. This paper describes plans for an operational field test called the THunderstorm Operational Research (THOR) Project beginning in 2002, the primary goals of which are to: 1) Reduce the number of Thunderstorm-related Air Traffic Delays with in the National Airspace System (NAS) and, 2) Improve severe thunderstorm, tornado and airport thunderstorm warning accuracy and lead time. Aviation field operations will be focused on the prime air traffic bottleneck in the NAS, the airspace bounded roughly by Chicago, New York City and Washington D.C., sometimes called the Northeast Corridor. A variety of new automated thunderstorm forecasting applications will be tested here that, when implemented into FAA-NWS operations, will allow for better tactical decision making and NAS management during thunderstorm days. Severe thunderstorm operations will be centered on Northern Alabama. NWS meteorologists from the forecast office in Birmingham will test the utility of experimental lightning, radar, and profiler data from a mesoscale observing network being established by NASA's Marshall Space Flight Center. In addition, new tornado detection and thunderstorm nowcasting algorithms will be examined for their potential for improving warning accuracy. The Alabama THOR site will also serve as a test bed for new gridded, digital thunderstorm and flash flood warning products.

Smith, Stephan B.↗
DOE OSTI2014

SU-E-T-17: A Mathematical Model for PinPoint Chamber Correction in Measuring Small Fields

Purpose: For small field dosimetry, such as measuring the cone output factor for stereotactic radiosurgery, ion chambers often result in underestimation of the dose, due to both the volume averaging effect and the lack of electron equilibrium. The purpose of this work is to develop a mathematical model, specifically for the pinpoint chamber, to calculate the correction factors corresponding to different type of small fields, including single cone-based circular field and non-standard composite fields. Methods: A PTW 0.015cc PinPoint chamber was used in the study. Its response in a certain field was modeled as the total contribution of many small beamlets, each with different response factor depending on the relative strength, radial distance to the chamber axis, and the beam angle. To get these factors, 12 cone-shaped circular fields (5mm,7.5mm, 10mm, 12.5mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 50mm, 60mm) were irradiated and measured with the PinPoint chamber. For each field size, hundreds of readings were recorded for every 2mm chamber shift in the horizontal plane. These readings were then compared with the theoretical doses as obtained with Monte Carlo calculation. A penalized-least-square optimization algorithm was developed to find out the beamlet response factors. After the parameter fitting, the established mathematical model was validated with the same MC code for other non-circular fields. Results: The optimization algorithm used for parameter fitting was stable and the resulted response factors were smooth in spatial domain. After correction with the mathematical model, the chamber reading matched with the Monte Carlo calculation for all the tested fields to within 2%. Conclusion: A novel mathematical model has been developed for the PinPoint chamber for dosimetric measurement of small fields. The current model is applicable only when the beam axis is perpendicular to the chamber axis. It can be applied to non-standard composite fields. Further validation with other type of detectors is being conducted.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Deep Borehole Laboratory and Borehole Testing Strategy: Generic Drilling and Testing Plan

This report presents a generic (i.e., site-independent) preliminary plan for drilling, testing, sampling, and analyzing data for a deep characterization borehole drilled into crystalline basement for the purposes of assessing the suitability of a site for deep borehole disposal (DBD). This research was performed as part of the deep borehole field test (DBFT). Based on revised U.S. Department of Energy (DOE) priorities in mid-2017, the DBFT and other research related to a DBD option was discontinued; ongoing work and documentation were closed out by the end of fiscal year (FY) 2017. This report was initiated as part of the DBFT and documented as an incomplete draft at the end of FY 2017. The report was finalized by Sandia National Laboratories in FY2018 without DOE funding, subsequent to the termination of the DBFT, and published in FY2019. This report presents a possible sampling, testing, and analysis campaign that could be carried out as part of a future project to quantify geochemical, geomechanical, geothermal, and geohydrologic conditions encountered at depths up to 5 km in crystalline basement.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

A Fiber-Optic Borehole Seismic Vector Sensor System for Geothermal Site Characterization and Monitoring

Seismic techniques are the dominant geophysical techniques for the characterization of subsurface structures and stratigraphy. The seismic techniques also dominate the monitoring and mapping of reservoir injection and production processes. Borehole seismology, of all the seismic techniques, despite its current shortcomings, has been shown to provide the highest resolution characterization and most precise monitoring results because it generates higher signal to noise ratio and higher frequency data than surface seismic techniques. The operational environments for borehole seismic instruments are however much more demanding than for surface seismic instruments making both the instruments and the installation much more expensive. The current state-of-the-art borehole seismic instruments have not been robust enough for long term monitoring compounding the problems with expensive instruments and installations. Furthermore, they have also not been able to record the large bandwidth data available in boreholes or having the sensitivity allowing them to record small high frequency micro seismic events with high vector fidelity. To reliably achieve high resolution characterization and long term monitoring of Enhanced Geothermal Systems (EGS) sites a new generation of borehole seismic instruments must therefore be developed and deployed. To address the critical site characterization and monitoring needs for EGS programs, US Department of Energy (DOE) funded Paulsson, Inc. in 2010 to develop a fiber optic based ultra-large bandwidth clamped borehole seismic vector array capable of deploying up to one thousand 3C sensor pods suitable for deployment into ultra-high temperature and high pressure boreholes. Tests of the fiber optic seismic vector sensors developed on the DOE funding have shown that the new borehole seismic sensor technology is capable of generating outstanding high vector fidelity data with extremely large bandwidth: 0.01 – 6,000 Hz. Field tests have shown that the system can record events at magnitudes much smaller than M-2.6 at frequencies up to 2,000 Hz. The sensors have also proved to be about 100 times more sensitive than the regular coil geophones that are used in borehole seismic systems today. The fiber optic seismic sensors have furthermore been qualified to operate at temperatures over 300°C (572°F). Simultaneously with the fiber optic based seismic 3C vector sensors we are using the lead-in fiber to acquire Distributed Acoustic Sensor (DAS) data from the surface to the bottom of the vector array. While the DAS data is of much lower quality than the vector sensor data it provides a 1 m spatial sampling of the downgoing wavefield which will be used to build the high resolution velocity model which is an essential component in high resolution imaging and monitoring.

15 GEOTHERMAL ENERGY↗
DOE OSTI2018

An Overview of the EGS Collab Project: Field Validation of Coupled Process Modeling of Fracturing and Fluid Flow at the Sanford Underground Research Facility, Lead, SD

Enhanced Geothermal Systems (EGS) development will require an ability to accurately predict the flow rates and temperatures of the production wells. While simple in concept, complex heterogeneous fracture pathways can lead to channeling, short-circuiting, and premature thermal breakthrough complicating EGS. The EGS Collab project will establish a suite of intermediate-scale (~10-20 m) field test beds coupled with stimulation and interwell flow tests to provide a basis to better understand the fracture geometries and processes that control heat transfer between rock and stimulated fractures. These experiments will provide a means of testing tools, codes, and concepts that could later be employed under geothermal reservoir conditions at FORGE and in EGS. We will perform well-controlled, in situ experiments focused on rock fracture behavior and permeability enhancement. Pre- and post-test modeling of each test will allow for model prediction and validation. Comprehensive instrumentation will be used to collect high-quality, high-resolution geophysical and fracture characterization and fluid flow data. ,These data will be analyzed and compared with models and field observations to further elucidate the basic relationships between stress, induced seismicity, and permeability enhancement. To the maximum extent achievable, we will observe and quantify other key governing parameters that impact permeability, and attempt to understand how these parameters might change throughout the development and operation of an EGS project with the goal of enabling commercial viability of EGS. The Sanford Underground Research Facility (SURF) in South Dakota was selected as the EGS Collab project experimental site based on the evaluation of information from several sites. Our team has designed and constructed the first field experiment planned for this project, which is supported by the US Department of Energy’s Geothermal Technologies Office.

EGS, FORGE, field fracture stimulation and flow ex↗
NASA NTRS1973

Evaluation of submarine strain-gage systems for monitoring coastal sediment migration

Single and multiple strain-gage systems were respectively evaluated as in situ point and areal sensors for monitoring sand-height variations in coastal environments. Static loading tests indicate that gage response pressure is linear for sand heights up to 24 inches. Response pressures are a function of both sand height and aggregate density, with density being influenced by both sediment texture and degree of compaction. Poorer sediment sorting and greater compaction result in higher response pressures. Field tests in a beach foreshore environment indicate that the gage systems are effective qualitative instruments for monitoring long-period migration trends of beach sediments; whereas, short-period responses are not sufficiently reliable. The durability and compactness of the gage systems must be substantially increased for effective field operations. It is recommended that the systems' qualitative potentials be further developed, whereas their development as quantitative instruments be terminated. Further development should emphasize the construction of remote recording systems designed for semipermanent installation.

Shideler, G. L.↗
DOE OSTI2018

Soiling and cleaning: Initial observations from 5-year photovoltaic glass coating durability study

The contamination of solar photovoltaic cover glass can significantly reduce the transmittance of light to the surface of the photovoltaic cell, reducing the module's power output. The solar industry has been developing antireflection (AR) and antisoiling (AS) surface coatings to enhance light transmittance and mitigate the impacts of soiling. Although uncoated glass has been field tested for decades, minimal data exist to demonstrate the durability of AR and AS coatings against abrasion and surface erosion, including from: natural weathering, airborne sand, and industry cleaning practices. Coupons 75 mm square of varying types have been field-deployed to gather long-term data on coating durability; the initial results are presented here after 1 year of outdoor exposure near Sacramento, California. Duplicate sets of coupons were cleaned monthly per four different cleaning practices. All coupons demonstrated inorganic soiling as well as microscale biological contamination, regardless of cleaning method. Additionally, full-sized, field-aged modules from other areas of the world presented with similar types of contamination as the field-aged coupons; micrographs and results from genomic sequencing of this contamination are included here. Optical microscopy, scanning electron microscopy, atomic force microscopy/energy-dispersive spectroscopy, surface roughness, transmittance, and surface energy analysis of representative specimens and cleaning practices are presented.

14 SOLAR ENERGY↗
DOE OSTI2017

CO 2 Capture by Cold Membrane Operation with Actual Power Plant Flue Gas

The main objective of the project was to develop a post-combustion CO 2 capture process based on the hybrid cold temperature membrane operation. The CO 2 in the flue gas from coal fired power plant is pre-concentrated to >60% CO 2 in the first stage membrane operation followed by further liquefaction of permeate stream to achieve >99% CO 2 purity. The aim of the project was based on DOE program goal of 90% CO 2 capture with >95% CO 2 purity from Pulverized Coal (PC) fired power plants with $40/tonne of carbon capture cost by 2025. The project moves the technology from TRL 4 to TRL 5. The project involved optimization of Air Liquide commercial 12” PI-1 bundle to improve the bundle productivity by >30% compared to the previous baseline (DE-FE0004278) using computational fluid dynamics (CFD) modeling and bundle testing with synthetic flue gas at 0.1 MWe bench scale skid located at Delaware Research and Technology Center (DRTC). In parallel, the next generation polyimide based novel PI-2 membrane was developed with 10 times CO 2 permeance compared to the commercial PI-1 membrane. The novel PI-2 membrane was scaled from mini-permeator to 1” permeator and 1” bundle for testing. Bundle development was conducted with a Development Spin Unit (DSU) installed at MEDAL. Air Liquide’s cold membrane technology was demonstrated with real coal fired flue gas at the National Carbon Capture Center (NCCC) with a 0.3 MWe field-test unit (FTU). The FTU was designed to incorporate testing of two PI-1 commercial membrane bundles (12” or 6” diameter) in parallel or series. A slip stream was sent to the next generation PI-2 membrane for testing with real flue gas. The system exceeded performance targets with stable PI-1 membrane operation for over 500 hours of single bundle, steady state testing. The 12” PI-1 bundle exceeded the productivity target by achieving ~600 Nm3/hr, where the target was set at ~455 Nm3/hr at 90% capture rate. The cost of 90% CO 2 capture from a 550 MWe net coal power plant was estimated between 40 and $45/tonne. A 6” PI-1 bundle exhibited superior bundle performance compared to the 12” PI-1 bundle. However, the carbon capture cost was not lower with the 6” PI-1 bundle due to the higher bundle installed cost. A 1” PI-1 bundle was tested to compare bundles with different length / diameter ratios. This bundle exhibited the lowest performance due to the different fiber winding pattern and increased bundle non-ideality. Several long-term and parametric tests were conducted with 3,200 hours of total run-time at NCCC. Finally, the new PI-2 membrane fiber was tested at a small scale (1” modules) in real flue gas and exhibited up to 10 times the CO 2 permeance and slightly lower CO 2 /N 2 selectivity as the commercial PI-1 fiber. This corresponded to a projected 4 - 5 times increase in the productivity per bundle and a potential cost reduction of $3/tonne for CO2 capture, as compared with PI-1. An analytical campaign was conducted to trace different impurities such as NOx, mercury, Arsenic, Selenium in gas and liquid samples through the carbon capture system. An Environmental, Health and Safety (EH&S) analysis was completed to estimate emissions from a 550 MWe net power plant with carbon capture using cold membrane. A preliminary design and cost analysis was completed for 550 tpd (~25 MWe) plant to assess the capital investment and carbon capture cost for PI-1 and PI-2 membrane solutions from coal fired flue gas. A comparison was made with an amine based solution with significant cost advantage for the membrane at this scale. Additional preliminary design and cost analysis was completed between coal, natural gas and SMR flue gas for carbon capture at 550 tpd (~25 MWe) plant.

01 COAL, LIGNITE, AND PEAT↗
NASA NTRS1982

Automated longwall guidance and control vertical control subsystem, volume 1

A design, fabrication, and implementation of a horizon control of a longwall shearer was performed. This equipment was tested and demonstrated aboveground. This hardware was also installed on a longwall face. The feasibility of providing horizon control for a shearer was demonstrated aboveground. The feasibility of retrofitting the necessary sensors in a survivable manner was demonstrated underground. Subsequent field tests of a specific component, the natural background sensor, at a western location demonstrated the particular usefulness of this device on a wider application basis.

Griffiths, W. R.↗
NASA NTRS2015

LAVA Subsystem Integration and Testing for the RESOLVE Payload of the Resource Prospector Mission: Mass Spectrometers and Gas Chromatography

The Regolith and Environment Science & Oxygen and Lunar Volatile Extraction (RESOLVE) payload is part of Resource Prospector (RP) along with a rover and a lander that are expected to launch in 2020. RP will identify volatile elements that may be combined and collected to be used for fuel, air, and water in order to enable deeper space exploration. The Resource Prospector mission is a key part of In-Situ Resource Utilization (ISRU). The demand for this method of utilizing resources at the site of exploration is increasing due to the cost of resupply missions and deep space exploration goals. The RESOLVE payload includes the Lunar Advanced Volatile Analysis (LAVA) subsystem. The main instrument used to identify the volatiles evolved from the lunar regolith is the Gas Chromatograph-Mass Spectrometer (GC-MS). LAVA analyzes the volatiles emitted from the Oxygen and Volatile Extraction Node (OVEN) Subsystem. The objective of OVEN is to obtain, weigh, heat and transfer evolved gases to LAVA through the connection between the two subsystems called the LOVEN line. This paper highlights the work completed during a ten week internship that involved the integration, testing, data analysis, and procedure documentation of two candidate mass spectrometers for the LAVA subsystem in order to aid in determining which model to use for flight. Additionally, the examination of data from the integrated Resource Prospector '15 (RP' 15) field test will be presented in order to characterize the amount of water detected from water doped regolith samples.

RESOLVE↗
NASA NTRS2016

Lunar Advanced Volatile Analysis Integration and Testing

The Regolith and Environment Science Oxygen and Lunar Volatile Extraction (RESOLVE) payload is part of Resource Prospector (RP) along with a rover and a lander that are expected to launch in 2020. RP will identify volatile elements that may be combined and collected to be used for fuel, air, and water in order to enable deeper space exploration. The Resource Prospector mission is a key part of In-Situ Resource Utilization (ISRU). The demand for this method of utilizing resources at the site of exploration is increasing due to the cost of resupply missions and deep space exploration goals. The RESOLVE payload includes the Lunar Advanced Volatile Analysis (LAVA) subsystem. The main instrument used to identify the volatiles evolved from the lunar regolith is the Gas Chromatograph-Mass Spectrometer (GC-MS). LAVA analyzes the volatiles emitted from the Oxygen and Volatile Extraction Node (OVEN) Subsystem. The objective of OVEN is to obtain, weigh, heat and transfer evolved gases to LAVA through the connection between the two subsystems called the LOVEN line. This paper highlights the work completed during a ten week internship that involved the integration, testing, data analysis, and procedure documentation of two candidate mass spectrometers for the LAVA subsystem in order to aid in determining which model to use for flight. Additionally, the examination of data from the integrated Resource Prospector '15 (RP' 15) field test will be presented in order to characterize the amount of water detected from water doped regolith samples.

In-Situ Resource Utilization↗
DOE OSTI2016

SU-G-BRB-16: Vulnerabilities in the Gamma Metric

Purpose: To explore vulnerabilities in the gamma index metric that undermine its wide use as a radiation therapy quality assurance tool. Methods: 2D test field pairs (images) are created specifically to achieve high gamma passing rates, but to also include gross errors by exploiting the distance-to-agreement and percent-passing components of the metric. The first set has no requirement of clinical practicality, but is intended to expose vulnerabilities. The second set exposes clinically realistic vulnerabilities. To circumvent limitations inherent to user-specific tuning of prediction algorithms to match measurements, digital test cases are manually constructed, thereby mimicking high-quality image prediction. Results: With a 3 mm distance-to-agreement metric, changing field size by ±6 mm results in a gamma passing rate over 99%. For a uniform field, a lattice of passing points spaced 5 mm apart results in a passing rate of 100%. Exploiting the percent-passing component, a 10×10 cm{sup 2} field can have a 95% passing rate when an 8 cm{sup 2}=2.8×2.8 cm{sup 2} highly out-of-tolerance (e.g. zero dose) square is missing from the comparison image. For clinically realistic vulnerabilities, an arc plan for which a 2D image is created can have a >95% passing rate solely due to agreement in the lateral spillage, with the failing 5% in the critical target region. A field with an integrated boost (e.g whole brain plus small metastases) could neglect the metastases entirely, yet still pass with a 95% threshold. All the failure modes described would be visually apparent on a gamma-map image. Conclusion: The %gamma<1 metric has significant vulnerabilities. High passing rates can obscure critical faults in hypothetical and delivered radiation doses. Great caution should be used with gamma as a QA metric; users should inspect the gamma-map. Visual analysis of gamma-maps may be impractical for cine acquisition.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Conducting Slug Tests in Mini-Piezometers: B.G. Fritz Ground Water xx, no. x: x-xx

Slug tests performed using mini-piezometers with diameters as small as 0.43 cm can provide a cost effective tool for hydraulic characterization. We evaluated the hydraulic properties of the apparatus in an infinite hydraulic conductivity environment and compared those results with field tests of mini-piezometers installed into locations with varying hydraulic properties. Based on our evaluation, slug tests conducted in mini-piezometers using the fabrication and installation approach described here are effective within formations where the hydraulic conductivity is less than 1 x 10-3 cm/s. While these constraints limit the potential application of this method, the benefits to this approach are that the installation, measurement and analysis is extremely cost effective, and the installation can be completed in areas where other (larger diameter) methods might not be possible. Additionally, this methodology could be applied to existing mini-piezometers previously installed for other purposes. Such analysis of existing installations could be beneficial in interpreting previously collected data (e.g. water quality data or hydraulic head data).

hyporheic zone↗
DOE OSTI2021

Low-Cost, Accessible Vaccine Cooler Options

In response to cold chain management requirements for COVID-19 vaccines, Los Alamos National Laboratory has investigated, built, and demonstrated viability for different cryogenic storage options. With ease-of-access and affordability in mind, these cooler units have been built using commercial off-the-shelf (COTS) components. The team was also able to design a testing method for evaluating the performance of the different vaccine cooler options as part of the Technology Evaluation and Demonstration program. The tested cooler units demonstrated compatibility with either dry ice or liquid nitrogen as the cryogen, along with several commercial solvents. This compatibility demonstration would potentially offer sufficient flexibility for temperature control continuity. Next steps are to investigate industry interest in supporting field testing of the cooler units.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2010

Daytime Water Detection Based on Color Variation

Robust water detection is a critical perception requirement for unmanned ground vehicle (UGV) autonomous navigation. This is particularly true in wide open areas where water can collect in naturally occurring terrain depressions during periods of heavy precipitation and form large water bodies (such as ponds). At far range, reflections of the sky provide a strong cue for water. But at close range, the color coming out of a water body dominates sky reflections and the water cue from sky reflections is of marginal use. We model this behavior by using water body intensity data from multiple frames of RGB imagery to estimate the total reflection coefficient contribution from surface reflections and the combination of all other factors. Then we describe an algorithm that uses one of the color cameras in a forward- looking, UGV-mounted stereo-vision perception system to detect water bodies in wide open areas. This detector exploits the knowledge that the change in saturation-to-brightness ratio across a water body from the leading to trailing edge is uniform and distinct from other terrain types. In test sequences approaching a pond under clear, overcast, and cloudy sky conditions, the true positive and false negative water detection rates were (95.76%, 96.71%, 98.77%) and (0.45%, 0.60%, 0.62%), respectively. This software has been integrated on an experimental unmanned vehicle and field tested at Ft. Indiantown Gap, PA.

reflection coefficient↗
NASA NTRS2020

Design and Test of an Electromechanical Rover Tether for the Exploration of Vertical Lunar Pit

Moon Diver is a proposed mission to land and deploy an extreme-terrain, tethered rover for the exploration of Tranquillitatis Pit, a large vertical cave entrance into the subsurface of Earth’s Moon. By leveraging a supportive tether, the Axel rover, developed by NASA’s Jet Propulsion Laboratory, would perform a controlled descent into the pit and deploy instruments along the pit wall. The purpose of this mission concept is to study a volcanic secondary crust as a function of depth in order to determine formation processes and chemical makeup. The lifeline of the mission would be the tether, which provides power from, and communication to the top-side lander. Critically, the tether also serves as mechanical support between the suspended rover and the lander, which acts as an anchor. While space tethers have been deployed both in orbit and terrestrially, the use of the proposed tether is unlike any known in the literature; the tether must come into contact with the terrain while under load. With respect to the environment, the tether must also survive abrasion from glassy regolith and volcanic rocks, bending around sharp edges, thermal extremes, and exposure to full spectrum ultra-violet (UV) radiation, all while reliably transferring up to 100 W of power and 1 Mbps of data. Furthermore, since the Axel rover pays out tether from an internal spool, the tether’s diameter must be minimized to increase spool capacity, allowing for up to a 300-m traverse while also meeting static and dynamic strength requirements. This paper covers several phases of the tether’s initial development, including i) a trade study of structure and materials with consideration for space heritage, ii) selected design justification, and iii) results from tests on prototype tethers looking into mechanical, electrical, and environmental properties, including exposure to rock regolith abrasion, load profiles at temperature, and degradation due to UV exposure while exposed to vacuum. Finally, we provide insights and lessons learned from lab and field tests, which inform our continued effort to design a tether capable of surviving rugged, lunar conditions.

Nensas, Issa↗
DOE OSTI2011

The XMM-BCS galaxy cluster survey: I. The X-ray selected cluster catalog from the initial 6 deg$^2$

The XMM-Newton - Blanco Cosmology Survey project (XMM-BCS) is a coordinated X-ray, optical and mid-infrared cluster survey in a field also covered by Sunyaev-Zel dovich effect (SZE) surveys by the South Pole Telescope and the Atacama Cosmology Telescope. The aim of the project is to study the cluster population in a 14 deg{sup 2} field (center: {alpha} {approx} 23:29:18.4, {delta} {approx} -54:40:33.6). The uniform multi-wavelength coverage will also allow us for the first time to comprehensively compare the selection function of the different cluster detection approaches in a single test field and perform a cross-calibration of cluster scaling relations. In this work, we present a catalog of 46 X-ray selected clusters from the initial 6 deg{sup 2} survey core.We describe the XMM-BCS source detection pipeline and derive physical properties of the clusters. We provide photometric redshift estimates derived from the BCS imaging data and spectroscopic redshift measurements for a low redshift subset of the clusters. The photometric redshift estimates are found to be unbiased and in good agreement with the spectroscopic values. Our multi-wavelength approach gives us a comprehensive look at the cluster and group population up to redshifts z {approx} 1. The median redshift of the sample is 0.47 and the median mass M{sub 500} {approx} 1 x 10{sup 14} M{sub {circle_dot}} ({approx} 2 keV). From the sample, we derive the cluster log N - log S using an approximation to the survey selection function and find it in good agreement with previous studies. We compare optical mass estimates from the Southern Cosmology Survey available for part of our cluster sample with our estimates derived from the X-ray luminosity. Weak lensing masses available for a subset of the cluster sample are in agreement with our estimates. Optical masses based on cluster richness and total optical luminosity are found to be significantly higher than the X-ray values. The present results illustrate the excellent potential of medium-deep, X-ray surveys to deliver cluster samples for cosmological modelling. In combination with available multi-wavelength data in optical, near-infrared and SZE, this will allow us to probe the dependence of the selection functions on relevant cluster observables and provide thus an important input for upcoming large-area multi-wavelength cluster surveys.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗