SEARCH · Search NASA

Results for “floating array”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

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

At least 109 records · Page 6

All sources NASA NTRS DOE OSTI

NASA NTRS2004

ISS Plasma Interaction: Measurements and Modeling

Ionospheric plasma interaction effects on the International Space Station are discussed in the following paper. The large structure and high voltage arrays of the ISS represent a complex system interacting with LEO plasma. Discharge current measurements made by the Plasma Contactor Units and potential measurements made by the Floating Potential Probe delineate charging and magnetic induction effects on the ISS. Based on theoretical and physical understanding of the interaction phenomena, a model of ISS plasma interaction has been developed. The model includes magnetic induction effects, interaction of the high voltage solar arrays with ionospheric plasma, and accounts for other conductive areas on the ISS. Based on these phenomena, the Plasma Interaction Model has been developed. Limited verification of the model has been performed by comparison of Floating Potential Probe measurement data to simulations. The ISS plasma interaction model will be further tested and verified as measurements from the Floating Potential Measurement Unit become available, and construction of the ISS continues.

Barsamian, H.↗

NASA NTRS1988

Preliminary results from the NASA/JPL multifrequency, multipolarization synthetic aperture radar

A brief description is given of the three-frequency polarimetric synthetic-aperture radar built and tested at the Jet Propulsion Laboratory. The radar has the capability to simultaneously acquire fully polarimetric data at P-, L-, and C-bands from a DC-8 airborne platform. The radar has an instantaneous data rate of approximately 2.1 Gb/s and has selectable record rates between 80-240 Mb/s. The system has a wide dynamic range featuring 8-b analog-to-digital converters and full digital floating-point processing. The processing is accomplished offline on a minicomputer system assisted by an array processor. Sample images are presented.

Held, Daniel N.↗

NASA NTRS1990

Accurate GPS measurement of the location and orientation of a floating platform

This article describes the design and initial tests of the GPS portion of a system for making seafloor geodesy measurements. In the planned system, GPS antennas on a floating platform will be used to measure the location of an acoustic transducer, attached below the platform, which interrogates an array of transponders on the seafloor. Since the GPS antennas are necessarily some distance above the transducer, a short-baseline GPS interferometer consisting of three antennas is used to measure the platform's orientation. A preliminary test of several crucial elements of the system was performed. The test involved a fixed antenna on the pier and a second antenna floating on a buoy about 80 m away. GPS measurements of the vertical component of this baseline, analyzed independently by two groups using different software, agree with each other and with an independent measurement within a centimeter. The first test of an integrated GPS/acoustic system took place in the Santa Cruz Basin off the coast of southern California in May 1990. In this test a much larger buoy, designed and built at SIO, was equipped with three GPS antennas and an acoustic transducer that interrogated a transponder on the ocean floor. Preliminary analysis indicates that the horizontal position of the transponder can be determined with a precision of about a centimeter.

Purcell, G. H., Jr.↗

NASA NTRS1983

The pulse profile of the Crab pulsar in the energy range 45 keV-1.2 MeV

The Crab Nebula pulsar (PSR 0531+21) is the best studied and most intense of the nontransient X-ray pulsars. However, since its spectrum drops rapidly with energy, a well-resolved pulse profile has not previously been obtained above 200 keV. In the hard X-ray and low-energy gamma-ray region, an accurate pulse profile can be obtained with a balloon-borne detector of sufficient area during a single transit of the source. A new measurement of the pulse profile of PSR 0531+21 in the energy range above 45 keV obtained with a large-area scintillation detector array is reported. The detector array was flown on a balloon launched from Palestine, Texas on 1980 October 6, reaching a float altitude 4.5 g/sq cm at 0230 UTC October 7. The primary objective of the experiment was to detect and study weak gamma-ray bursts.

Wilson, R. B.↗

NASA NTRS2001

A Radiation-Tolerant, Low-Power Non-Volatile Memory Based on Silicon Nanocrystal Quantum Dots

Nanocrystal nonvolatile floating-gate memories are a good candidate for space applications - initial results suggest they are fast, more reliable and consume less power than conventional floating gate memories. In the nanocrystal based NVM device, charge is not stored on a continuous polysilicon layer (so-called floating gate), but instead on a layer of discrete nanocrystals. Charge injection and storage in dense arrays of silicon nanocrystals in SiO2 is a critical aspect of the performance of potential nanocrystal flash memory structures. The ultimate goal for this class of devices is few- or single-electron storage in a small number of nanocrystal elements. In addition, the nanocrystal layer fabrication technique should be simple, 8-inch wafer compatible and well controlled in program/erase threshold voltage swing was seen during 100,000 program and erase cycles. Additional near-term goals for this project include extensive testing for radiation hardness and the development of artificial layered tunnel barrier heterostructures which have the potential for large speed enhancements for read/write of nanocrystal memory elements, compared with conventional flash devices. Additional information is contained in the original extended abstract.

Bell, L. D.↗

NASA NTRS2001

A radiation - tolerant, low - power non - volatile memory based on silicon nanocrystal quantum dots.

Green, M. L.↗

NASA NTRS2017

Application of IRTAM to Support ISS Program Safety

The International Space Station (ISS) orbits near the F-peak of the ionosphere (approximately 400 km altitude). Generally, satellites orbiting at this altitude would have a floating potential (FP) of approximately -1 V due to the electron temperature (Te). However, the ISS has 8 large negatively grounded 160 V solar array wings (SAW) that collect a significant electron current from the ionosphere. This current drives the ISS FP much more negative during insolation and is highly dependent on the electron density (Ne). Also, due to the size of the ISS, magnetic inductance caused by the geomagnetic field produces a delta potential up to 40 V across the truss, possibly producing positive potentials. During Extravehicular Activity (EVA) the negative FP can lead to an arcing hazard when it exceeds -45.5 V, and the positive FP can produce a DC current high enough to stimulate the astronaut's muscles and also cause a hazard. Data collected from the Floating Potential Monitoring Unit (FPMU) have shown that the probability of either of these hazards occurring during times with quiet to moderately disturbed geomagnetic activity is low enough to no longer be considered a risk. However, a study of the ionosphere Ne during severe geomagnetic storm activity has shown that the Ne can be enhanced by a factor of 6 in the ISS orbit. As a result, the ISS Safety Review Panel (SRP) requires that ionospheric conditions be monitored using the FPMU in conjunction with the ISS Plasma Interaction Model (PIM) to determine if a severe geomagnetic storm could result in a plasma environment that could produce a hazard. A 'Real-Time' plasma hazard assessment process was developed to support ISS Program real-time decision making providing constraint relief information for EVAs planning and operations. This process incorporates 'real time' ionospheric conditions, ISS solar arrays' orientation, ISS flight attitude, and where the EVA will be performed on the ISS. This assessment requires real time data that is presently provided by the FPMU including ISS floating potential, along with ionospheric Ne and Te, in order to determine the present environment. Once the present environment conditions are known to be either above, below, or near the current IRI values, the IRI is used to forecast what the environment could become in the event of a severe geomagnetic storm. If the FPMU should fail, the Space Environments team needs another source of data which is utilized to support a short-term forecast for EVAs. The IRI Real-Time Assimilative Mapping (IRTAM) model is an ionospheric model that uses real time measurements from approximately 70 digisondes to produce foF2 and hmF2 global maps in 15 minute cadence. The Boeing Space Environments team has used the IRI coefficients produced in IRTAM to calculate the Ne along the ISS orbital track. The results of the IRTAM model have been compared to FPMU measurements and show excellent agreement (figure 1). IRTAM has been identified as a potential FPMU back-up system will be used as a backup for the FPMU to support the ISS Program following completion of an FPMU/IRTAM validation campaign.

Hartman, William A.↗

NASA NTRS1976

Probe studies in a modified penning discharge

The axial and radial floating potential distribution in a modified Penning discharge were studied at different values of the background pressure, discharge voltage, and magnetic field. An array of small disc probes arranged radially with their planes perpendicular to the magnetic field and movable along the axial direction was inserted in the plasma through one open end of the magnetic mirror system. Results show that depending on the operating conditions, the discharge can undergo different mode transitions in which the plasma can sustain different floating potentials in the radial as well as in the axial directions. Preliminary results of measurement, using RF probes in the modified Penning discharge plasma are also discussed.

Sen, C.↗

NASA NTRS2010

Integration Assessment of Visiting Vehicle Induced Electrical Charging of the International Space Station Structure

The International Space Station (ISS) undergoes electrical charging in low Earth orbit (LEO) due to positively biased, exposed conductors on solar arrays that collect electrical charges from the space plasma. Exposed solar array conductors predominately collect negatively charged electrons and thus drive the metal ISS structure electrical ground to a negative floating potential (FP) relative to plasma. This FP is variable in location and time as a result of local ionospheric conditions. ISS motion through Earth s magnetic field creates an addition inductive voltage up to 20 positive and negative volts across ISS structure depending on its attitude and location in orbit. ISS Visiting Vehicles (VVs), such as the planned Orion crew exploration vehicle, contribute to the ISS plasma charging processes. Upon physical contact with ISS, the current collection properties of VVs combine with ISS. This is an ISS integration concern as FP must be controlled to minimize arcing of ISS surfaces and ensure proper management of extra vehicular activity crewman shock hazards. This report is an assessment of ISS induced charging from docked Orion vehicles employing negatively grounded, 130 volt class, UltraFlex (ATK Space Systems) solar arrays. To assess plasma electron current collection characteristics, Orion solar cell test coupons were constructed and subjected to plasma chamber current collection measurements. During these tests, coupon solar cells were biased between 0 and 120 V while immersed in a simulated LEO plasma. Tests were performed using several different simulated LEO plasma densities and temperatures. These data and associated theoretical scaling of plasma properties, were combined in a numerical model which was integrated into the Boeing Plasma Interaction Model. It was found that the solar array design for Orion will not affect the ISS FP by more than about 2 V during worst case charging conditions. This assessment also motivated a trade study to determine acceptable plasma electron current levels that can be collected by a single or combined fleet of ISS-docked VVs.

Kramer, Leonard↗

NASA NTRS1976

Probe studies in a modified Penning discharge

The axial and radial floating potential distribution in a modified Penning discharge have been studied at different values of the background pressure, discharge voltage, and magnetic field. An array of small disc probes arranged radially with their planes perpendicular to the magnetic field and movable along the axial direction was inserted in the plasma through one open end of the magnetic mirror system. Results show that depending on the operating conditions, the discharge can undergo different mode transitions in which the plasma can sustain different floating potentials in the radial as well as in the axial directions. Preliminary results of measurement, using RF probes in the modified Penning discharge plasma are also discussed.

Sen, C.↗

NASA NTRS1980

Preliminary study on the potential usefulness of array processor techniques for structural synthesis

The effects of the use of array processor techniques within the structural analyzer program, SPAR, are simulated in order to evaluate the potential analysis speedups which may result. In particular the connection of a Floating Point System AP120 processor to the PRIME computer is discussed. Measurements of execution, input/output, and data transfer times are given. Using these data estimates are made as to the relative speedups that can be executed in a more complete implementation on an array processor maxi-mini computer system.

Feeser, L. J.↗

NASA NTRS2007

FPP [Floating Potential Probe] Results, Final Report

The Floating Potential Probe (FPP) operated on the International Space Station (ISS) from December 2000 to April 2001. During that time, it took many measurements of the ISS floating potential and the electron density and temperature. Those measurements were used as inputs to the Environments WorkBench (EWB) model of ISS potentials (originally developed by SAIC, but now sometimes called the Boeing model) that is used even today to predict charging levels for ISS. FPP is now completely defunct, having been removed and ejected from ISS. With the advent of the new Floating Potential Monitoring Unit (FPMU) on ISS, and the beginning of ISS operations with two large solar array panels instead of just one, a review of FPP measurements can offer comparisons with the new FPMU data and perhaps improve the accuracy of future ISS charging predictions. In particular, FPP measurements during times of low electron temperature and high electron density (the times of worst ISS charging) will be brought forward for comparison with the newly obtained FPMU data.

Ferguson, Dale C.↗

NASA NTRSDate not supplied

Performance Optimization Methods for a Memory-Bound, Unstructured-Grid CFD Application on Massively Parallel GPU Platforms

Computational performance of the FUN3D unstructured-grid computational fluid dynamics (CFD) application on massively parallel GPU environments is memory-bound and highly dependent upon efficient reads from and atomic updates to the irregular cell-, edge-, and node-based data structures. In this talk, we present recent efforts into optimizing select performance-critical kernels on NVIDIA Tesla V100 and A100 GPUs and AMD CDNA MI100 GPUs. A novel use of L2 cache residency controls and asynchronous loads into on-chip shared memory are explored on the A100 GPU for the sparse iterative solver, which is dominated by mixed-precision, sparse matrix vector multiplication. Demonstrations show that these methods improve global memory bandwidth utilization by 13.5% on the A100 GPU. Several techniques are also presented that use registers and/or shared memory to facilitate array transposition and aggregation which combine to reduce the frequency and increase the cache efficiency of floating-point atomic updates to the irregular data structures. These methods are demonstrated to improve the kernel throughput by nearly 500% on select kernels on the AMD MI100 over atomic updates directly to global memory. Overall, both V100 and A100 GPUs outperformed the MI100 GPU on kernels dominated by double-precision atomic updates; however, the techniques demonstrated here reduced the performance gap and improved the MI100 performance.

GPU CPU unstructured CFD memory↗

NASA NTRS1999

Manipulating Liquids With Acoustic Radiation Pressure Phased Arrays

High-intensity ultrasound waves can produce the effects of "Acoustic Radiation Pressure" (ARP) and "acoustic streaming." These effects can be used to propel liquid flows and to apply forces that can be used to move or manipulate floating objects or liquid surfaces. NASA's interest in ARP includes the remote-control agitation of liquids and the manipulation of bubbles and drops in liquid experiments and propellant systems. A high level of flexibility is attained by using a high-power acoustic phased array to generate, steer, and focus a beam of acoustic waves. This is called an Acoustic Radiation Pressure Phased Array, or ARPPA. In this approach, many acoustic transducer elements emit wavelets that converge into a single beam of sound waves. Electronically coordinating the timing, or "phase shift," of the acoustic waves makes it possible to form a beam with a predefined direction and focus. Therefore, a user can direct the ARP force at almost any desired point within a liquid volume. ARPPA lets experimenters manipulate objects anywhere in a test volume. This flexibility allow it to be used for multiple purposes, such as to agitate liquids, deploy and manipulate drops or bubbles, and even suppress sloshing in spacecraft propellant tanks.

Oeftering, Richard C.↗

DOE OSTI2024

Advanced Laboratory and Field Arrays (ALFA)/Lab Collaboration Project (LCP) for Marine Energy (Final Scientific/Technical Report)

The objective of the Advanced Laboratory and Field Arrays (ALFA) project was to reduce the Levelized Cost of Energy (LCOE) of Marine and Hydrokinetic (MHK) energy by leveraging research, development, and testing capabilities at Oregon State University, University of Washington, and the University of Alaska, Fairbanks. ALFA is a project within the Pacific Marine Energy Center (PMEC; formerly NNMREC), a multi-institution entity with a diverse funding base that focuses on research and development for marine renewables. The ALFA project aimed to accelerate the development of next-generation arrays of wave energy conversion (WEC) and tidal energy conversion (TEC) devices through a suite of field-focused R&D activities spanning a broad range of strategic opportunity areas identified in the Funding Opportunity Announcement: • Device and/or array operation and maintenance (O&M) logistics development; • High-fidelity resource characterization and/or modeling technique development and validation; • Array-specific component technology development (e.g. moorings and foundations, transmission, and other offshore grid components); • Array performance testing and evaluation; and • Novel cost-effective environmental monitoring techniques and instrumentation testing and evaluation. The objective of the Lab Collaboration Project (LCP) was to accelerate the development of next-generation marine energy conversion systems. The LCP aimed to achieve these project objectives in collaboration with the national laboratories by: • Developing concept generation and assessment tools; • Improving access to existing testing resources; • Validating collision risk models between fish and turbines; and • Advancing analysis and simulation capabilities for wave-WEC interactions and PTO analysis in nonlinear ocean waves. The ALFA portion of the project was comprised of six overarching technical tasks: • Task 1: Debris Modeling, Detection and Mitigation; • Task 2: Autonomous Monitoring & Intervention; • Task 3: Resource Characterization for Extreme Conditions; • Task 4: Robust Models for Design of Offshore Anchoring and Mooring Systems; • Task 5: Performance Enhancement for Marine Energy Converter (MEC) Arrays; and • Task 6: Evaluating Sampling Techniques for MHK Biological Monitoring. The LCP was divided into four overarching technical tasks: • Task 7: Project Management and Reporting • Task 8: Novel Design and Assessment Methodologies for Wave Energy Converter Design (Wave- SPARC) • Task 9: Testing Access for Commercial Marine Renewable Energy Technology Developers • Task 10: Quantifying Collision Risk for Fish and Turbines • Task 11: Nonlinear Ocean Waves and PTO Control Strategy Each ALFA/LCP task listed above functioned as a separate and discreet project. A final Technical Report was written for each individual task and these reports were uploaded to OSTI, after receiving DOE approval. The following document is a compilation of each of these final, approved reports arranged as individual chapters.

13 HYDRO ENERGY↗

NASA NTRS1982

Glasses for Solar-Cell Arrays

Report presents data on glass for encapsulation of solar-cell arrays, with special emphasis on materials and processes for automated high-volume production of low-cost arrays. Commercial suppliers of glass are listed. Factors that affect the cost of glass are examined: type (sheet, float, or plate), formulation, and energy consumed in manufacturing.

Bouquet, F. L.↗

DOE OSTI2025

Distributed Acoustic Sensing for Whale Vocalization Monitoring: A Vertical Deployment Field Test

Abstract There is growing interest in floating offshore wind turbine (FOWT) technology, where turbines are installed on floating structures anchored to the seabed, allowing wind energy development in areas unsuitable for traditional fixed-platform turbines. Responsible development requires monitoring the impact of FOWTs on marine wildlife, such as whales, throughout the operational lifecycle of the turbines. Distributed acoustic sensing (DAS)—a technology that transforms fiber-optic cables into vibration sensor arrays—has been demonstrated for acoustic monitoring of whales using seafloor telecommunications cables. However, no studies have yet evaluated DAS performance in dynamic, engineered environments, such as floating platforms or moving vessels with complex, dynamic strain loads, despite their relevance to FOWT settings. This study addresses that gap by deploying DAS aboard a boat in Monterey Bay, California, where a fiber-optic cable was lowered using a weighted and suspended mooring line, enabling vertical deployment. Humpback whale vocalizations were captured and identified in the DAS data, noise sources were identified, and DAS data were compared to audio captured by a standalone hydrophone attached to the mooring line and a nearby hydrophone on a cabled observatory. This study is unique in: (1) deploying DAS in a vertical deployment mode, where noise from turbulence, cable vibrations, and other sources posed additional challenges compared to seafloor DAS applications; (2) demonstrating DAS in a dynamic, nonstationary setup, which is uncommon for DAS interrogators typically used in more stable environments; and (3) leveraging looped sections of the cable to reduce the noise floor and mitigate the effects of excessive cable vibrations and strain. This research demonstrates DAS’s ability to capture whale vocalizations in challenging environments, highlighting its potential to enhance underwater acoustic monitoring, particularly in the context of renewable energy development in offshore environments.

Saw, Jaewon↗

NASA NTRS1981

The hot plasma environment and floating potentials of an electron-beam-emitting rocket in the ionosphere

The plasma environment surrounding the Echo III accelerator payload is examined with an extensive array of particle sensors. Suprathermal electrons are produced isotropically around the payload during the gun firings and decay away in approximately 32 ms. The largest directional intensities of this component are observed at the higher altitudes. Quick echo electrons are also observed to produce suprathermal electrons when they encounter the payload. The hot electrons surrounding the accelerator payload during gun injections bring sufficient charge to the payload to neutralize it provided the loss of charge by secondary production on the payload skin is small. Since the hot population exists for tens of milliseconds after the gun turnoff, it results in driving the payload up to 4 volts negative during this time. Quick echo electrons creating suprathermal electrons around the payload also drive the payload to a few volts negative.

Arnoldy, R. L.↗