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

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Three-Wave Mixing Kinetic Inductance Traveling-Wave Amplifier with Near-Quantum-Limited Noise Performance

We present a theoretical model and experimental characterization of a microwave kinetic inductance traveling-wave (KIT) amplifier, whose noise performance, measured by a shot-noise tunnel junction (SNTJ), approaches the quantum limit. Biased with a dc current, this amplifier operates in a three-wave mixing fashion, thereby reducing by several orders of magnitude the power of the microwave pump tone and associated parasitic heating compared to conventional four-wave mixing KIT amplifier devices. It consists of a 50 Ω artificial transmission line whose dispersion allows for a controlled amplification bandwidth. We measure $16.5^{+1}_{–1.3}$ dB of gain across a 2 GHz bandwidth with an input 1 dB compression power of –63 dBm, in qualitative agreement with theory. Using a theoretical framework that accounts for the SNTJ-generated noise entering both the signal and idler ports of the KIT amplifier, we measure the system-added noise of an amplification chain that integrates the KIT amplifier as the first amplifier. This system-added noise, 3.1 ± 0.6 quanta (equivalent to 0.66 ± 0.15 K) between 3.5 and 5.5 GHz, is the one that a device replacing the SNTJ in that chain would see. This KIT amplifier is therefore suitable to read large arrays of microwave kinetic inductance detectors and promising for multiplexed superconducting qubit readout.

42 ENGINEERING↗
DOE OSTI2024

Continuous automatic polarization channel stabilization from heterodyne detection of coexisting dim reference signals

Quantum networking continues to encode information in polarization states due to ease and precision. The variable environmental polarization transformations induced by deployed fiber need correction for deployed quantum networking. Here, we present a method for automatic polarization compensation (APC) and demonstrate its performance on a metropolitan quantum network. Designing an APC involves many design decisions as indicated by the diversity of previous solutions in the literature. Our design leverages heterodyne detection of wavelength-multiplexed dim classical references for continuous high-bandwidth polarization measurements used by newly developed multi-axis (non-)linear control algorithm(s) for complete polarization channel stabilization with no downtime. This enables continuous relatively high-bandwidth correction without significant added noise from classical reference signals. We demonstrate the performance of our APC using a variety of classical and quantum characterizations. Finally, we use C-band and L-band APC versions to demonstrate continuous high-fidelity entanglement distribution on a metropolitan quantum network with an average relative fidelity of 0.94 ± 0.03 for over 30 hrs.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1993

Evaluation Metrics for the Paragon XP/S-15

On February 17th 1993, the Numerical Aerodynamic Simulation (NAS) facility located at the NASA Ames Research Center installed a 224 node Intel Paragon XP/S-15 system. After its installation, the Paragon was found to be in a very immature state and was unable to support a NAS users' workload, composed of a wide range of development and production activities. As a first step towards addressing this problem, we implemented a set of metrics to objectively monitor the system as operating system and hardware upgrades were installed. The metrics were designed to measure four aspects of the system that we consider essential to support our workload: availability, utilization, functionality, and performance. This report presents the metrics collected from February 1993 to August 1993. Since its installation, the Paragon availability has improved from a low of 15% uptime to a high of 80%, while its utilization has remained low. Functionality and performance have improved from merely running one of the NAS Parallel Benchmarks to running all of them faster (between 1 and 2 times) than on the iPSC/860. In spite of the progress accomplished, fundamental limitations of the Paragon operating system are restricting the Paragon from supporting the NAS workload. The maximum operating system message passing (NORMA IPC) bandwidth was measured at 11 Mbytes/s, well below the peak hardware bandwidth (175 Mbytes/s), limiting overall virtual memory and Unix services (i.e. Disk and HiPPI I/O) performance. The high NX application message passing latency (184 microns), three times than on the iPSC/860, was found to significantly degrade performance of applications relying on small message sizes. The amount of memory available for an application was found to be approximately 10 Mbytes per node, indicating that the OS is taking more space than anticipated (6 Mbytes per node).

Traversat, Bernard↗
NASA NTRS2003

Detecting Near-Surface Water and Hydrate Minerals on Mars from a Rover, Penetrator, or Borehole: The HYDRA Instrument

One of the major goals of near term NASA Mars exploration is to identify exact locations of near-surface water or hydrated minerals on Mars. Evidence for the existence of recent nearsurface water on Mars underscores the need for developing instrumentation that can identify water or hydrated minerals very near the surface. Further encouraging evidence of surface and near-surface water and hydrate minerals on Mars comes from neutron spectrometer measurements aboard Mars Odyssey. Preliminary results show very large regions of high hydrogen content poleward of 60 deg. latitude, as well as interesting features closer to the equator. However, spatial resolution from orbit is very poor, approx. 400 km. The next logical step is to use in-situ or near-surface investigations to map in detail some of the most interesting features. Relatively simple instrumentation based on He-3 gas proportional counters were shown to be highly successful on the Lunar Prospector mission in identifying even low levels of enhanced hydrogen abundances. Here we discuss HYDRA, a water- and hydrate-sensing instrument currently being developed under the NASA Mars Instrument Development Program (MIDP). HYDRA is based on Lunar Prospector technology, and is intended as a rover body-mounted instrument, or an instrument on an aerobot, penetrator, hard lander on the surface of Mars, or for borehole stratigraphy applications. Our proposed instrument would be ideal for such platforms as it would be small (less than 7 cm diameter by 10 cm long), low mass (less than 500 g), low power (less than 1W), and have a low data volume per measurement. We use neutron spectrometry (a) because of its proven ability to uniquely detect and quantify hydrogen abundance, and (b) because the resources required by this approach (weight, power, size, telemetry bandwidth, and measurement time) are extremely low. This compact neutron spectrometer package, comprised of two small He-3 gas proportional counters, offers superior sensitivity, extensive flight heritage, and inherent ruggedness. These tubes have survived approx. 1500 g's of acceleration in penetrator tests. In a landed application, HYDRA would help address many topics of interest to the Mars Exploration and Astrobiology communities: (a) nature and origin of stratified deposits; (b) water cycle(s) and temporal changes; (c) early water oceans, aquifers, precipitation; (d) current extent/location/state of water; (e) polar cap processes and temporal changes; (f) where extremeophiles could survive on Mars; (g) paleoclimate surface signatures and modeling; (h) strategies for future Mars exploration.

R C Elphic↗
NASA NTRS1995

Image Discrimination Models With Stochastic Channel Selection

Many models of human image processing feature a large fixed number of channels representing cortical units varying in spatial position (visual field direction and eccentricity) and spatial frequency (radial frequency and orientation). The values of these parameters are usually sampled at fixed values selected to ensure adequate overlap considering the bandwidth and/or spread parameters, which are usually fixed. Even high levels of overlap does not always ensure that the performance of the model will vary smoothly with image translation or scale changes. Physiological measurements of bandwidth and/or spread parameters result in a broad distribution of estimated parameter values and the prediction of some psychophysical results are facilitated by the assumption that these parameters also take on a range of values. Selecting a sample of channels from a continuum of channels rather than using a fixed set can make model performance vary smoothly with changes in image position, scale, and orientation. It also facilitates the addition of spatial inhomogeneity, nonlinear feature channels, and focus of attention to channel models.

Ahumada, Albert J., Jr.↗
NASA NTRS1980

Miniature spectrally selective dosimeter

A miniature spectrally selective dosimeter capable of measuring selected bandwidths of radiation exposure on small mobile areas is described. This is achieved by the combination of photovoltaic detectors, electrochemical integrators (E-cells) and filters in a small compact case which can be easily attached in close proximity to and substantially parallel to the surface being measured. In one embodiment two photovoltaic detectors, two E-cells, and three filters are packaged in a small case with attaching means consisting of a safety pin. In another embodiment, two detectors, one E-cell, three filters are packaged in a small case with attaching means consisting of a clip to clip over a side piece of an eye glass frame.

Adams, R. R.↗
NASA NTRS2012

Root Raised Cosine (RRC) Filters and Pulse Shaping in Communication Systems

This presentation briefly discusses application of the Root Raised Cosine (RRC) pulse shaping in the space telecommunication. Use of the RRC filtering (i.e., pulse shaping) is adopted in commercial communications, such as cellular technology, and used extensively. However, its use in space communication is still relatively new. This will possibly change as the crowding of the frequency spectrum used in the space communication becomes a problem. The two conflicting requirements in telecommunication are the demand for high data rates per channel (or user) and need for more channels, i.e., more users. Theoretically as the channel bandwidth is increased to provide higher data rates the number of channels allocated in a fixed spectrum must be reduced. Tackling these two conflicting requirements at the same time led to the development of the RRC filters. More channels with wider bandwidth might be tightly packed in the frequency spectrum achieving the desired goals. A link model with the RRC filters has been developed and simulated. Using 90% power Bandwidth (BW) measurement definition showed that the RRC filtering might improve spectrum efficiency by more than 75%. Furthermore using the matching RRC filters both in the transmitter and receiver provides the improved Bit Error Rate (BER) performance. In this presentation the theory of three related concepts, namely pulse shaping, Inter Symbol Interference (ISI), and Bandwidth (BW) will be touched upon. Additionally the concept of the RRC filtering and some facts about the RRC filters will be presented

Cubukcu, Erkin↗
NASA NTRS1988

The design of an onboard digital Doppler processor for a spaceborne scatterometer

A digital Doppler processor, which will permit the Doppler center frequency of the measurement cell bandwidths to be adjusted to compensate for the effects of the earth's rotation, will be used in the next NASA spaceborn scatterometer known as NSCAT. The authors describe the design and genesis of the NSCAT digital Doppler processor and discusses the performance tradeoff issues that were evaluated during the design phase. In this FFT (fast Fourier transform)-based technique, computation of the adjustment to the cell center frequencies will be done onboard using an approximate expression for the Doppler shift of the cell center versus orbit time. This technique also permits modification of the parameters used to locate the radar-backscatter-coefficient measurement cells by ground command in response to orbit changes.

Long, David G.↗
DOE OSTI2020

Programming Strategies for Irregular Algorithms on the Emu Chick

The Emu Chick prototype implements migratory memory-side processing in a novel hardware system. Rather than transferring large amounts of data across the system interconnect, the Emu Chick moves lightweight thread contexts to near-memory cores before the beginning of each remote memory read. Previous work has characterized the performance of the Chick prototype in terms of memory bandwidth and programming differences from more typical, non-migratory platforms, but there has not yet been an analysis of algorithms on this system. This work evaluates irregular algorithms that could benefit from the lightweight, memory-side processing of the Chick and demonstrates techniques and optimization strategies for achieving performance in sparse matrix-vector multiply operation (SpMV), breadth-first search (BFS), and graph alignment across up to eight distributed nodes encompassing 64 nodelets in the Chick system. We also define and justify relative metrics to compare prototype FPGA-based hardware with established ASIC architectures. The Chick currently supports up to 68x scaling for graph alignment, 80 MTEPS for BFS on balanced graphs, and 50% of measured STREAM bandwidth for SpMV.

Hein, Eric↗
DOE OSTI2020

Quantitative Performance Assessment of Proxy Apps and Parents (ECP Proxy App Project Milestone ADCD-504-9)

This report presents highlights of these efforts. Section 2 describes work that has been done to compare the performance of proxy applications on AMD MI60 vs. Nvidia V100 GPUs. So far only a small set of ECP proxies are running on AMD GPUs, but we will continue to expand this analysis as additional proxies become available. We find that although the MI60 and V100 have nearly the same measured memory bandwidth, memory bound proxy app kernels perform 20-30% worse on the MI60. Further work is needed to refine these comparisons to determine whether the root cause is due to differences in the hardware, software stack, platform specific optimization, or some combination of the three. Section 3 describes our continuing effort to find methods to accurately assess the similarity of proxies and parents. We have recently seen very encouraging results using a cosine similarity metric. This technique uses the angle between two vectors of hardware performance counters to characterize the similarity (or difference) between two applications or proxies. We show not only that several widely used proxies are highly similar to their parents, but also that they differ from non-related codes. We also show that cosine similarity can be used to identify gaps and redundancies in suites and even to gain insight into the effects of architectural differences between platforms. Our work on assessing the Exascale toolchain is ongoing. Our successes with performance measurement tools are evident from the data provided in this report. However, our assessments across the broader tool chain are still too incomplete to provide a meaningful report at this time. We will continue to assess tools and work with vendors and third party developers as issues are identified.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Advanced Intelligent Sensor Development and Demonstration for Future Distribution Systems with High Penetration DERs

The nation’s electric grid is evolving to supply the electricity needed for economic growth, health, and quality of life. As the DOE has pointed out “Old Tools Won’t Solve New Problems” This project conceived, designed, built, and demonstrated a new tool that promises to make the emerging grid dependable at a lower cost. The tool is a smart sensor with the sensitivity and the bandwidth to measure actionable information about grid health that was unmeasurable.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1974

Far-infrared emission from H II regions. II - Multicolor photometry of selected sources and 2.2 min resolution maps of M42 and NGC 2024

Medium- and broad-bandwidth photometric measurements have been made of seven compact H II regions at wavelengths between 30 and 650 microns. The results are consistent with the hypothesis that the far-infrared flux is continuum radiation from dust grains. Color temperatures range from 33 to 85 K. For most of the sources, the infrared flux is low enough so that the dust could conceivably be mixed with the ionized gas. In at least one case, however, the far-infrared spectrum and luminosity of the source cannot be reconciled with reasonable grain models unless the far-infrared flux comes from a shell surrounding the H II region. M42 (Orion) and NGC 2024 (Orion B) have been mapped at 90 microns with a resolution (half-power beam diameter) of 2.2 min. Although the peak far-infrared brightness in M42 occurs at the position of the Kleinmann-Low infrared nebula, most of the flux originates in a more extended (about 6 x 8 min) source. The energy for the diffuse component could be supplied by the stars in the Trapezium cluster. However, the single early-type star visible in NGC 2024 is not luminous enough to account for either the infrared flux or the observed free-free flux.

Harper, D. A.↗
NASA NTRS1974

Amplification of microwaves by superconducting microbridges in a four-wave parametric mode

Parametric amplification of microwaves was observed using thin-film junctions of the Anderson-Dayem type. A series of 80 such junctions were incorporated into the upper conductor of a broadband 50-ohm microstrip transmission line with no DC bias. The amplifier was operated in the 'doubly degenerate' mode with signal, pump, and idler frequencies closely and equally spaced. An electronic gain of 12 dB at 10 GHz was observed. The bandwidth was measured to be 1 GHz and the noise temperature to be less than 20 K.

Parrish, P. T.↗
NASA NTRS1987

Model-based analysis of control/display interaction in the hover task

The effect of Control/Display interaction in the hover task is analyzed using an optimal control approach to modeling pilot control behavior. The control/display configurations considered are those previously evaluated in a flight research program. The experimental data-base is reviewed and the procedure for modeling the task and the displayed information is presented in detail. All model-based results, time-domain as well as frequency-domain, are found to correlate extremely well with the subjective pilot ratings and comments. Time-domain measures consist of root mean-square errors and control inputs, attention allocation to displayed quantities, and magnitudes of task objective function. Frequency-domain measures include bandwidth, stability margins, and pilot phase compensation. Results are also shown to agree with previous findings on task interference in multi-axis tasks.

Schmidt, David K.↗
NASA NTRS1991

Er:YLF-pumped AgGaSe2 optical parametric oscillator

An AgGaSe2 optical parametric oscillator, pumped by a 1.73-micron Er:YLF laser, has demonstrated reproducible low thresholds, 3.6 mJ, and high-slope efficiencies, 0.31. Threshold and slope efficiency were investigated as a function of resonator length. Spectral bandwidth was measured and correlated with the beam divergence of the pump laser.

Barnes, Norman↗
NASA NTRS1992

Bandwidth and SIMDUCE as simulator fidelity criteria

The potential application of two concepts from the new Handling Qualities Specification for Military Rotorcraft was discussed. The first concept is bandwidth, a measure of the dynamic response to control. The second is a qualitative technique developed for assessing the visual cue environment the pilot has in bad weather and at night. Simulated Day Usable Cue Environment (SIMDUCE) applies this concept to assessing the day cuing fidelity in the simulator.

Key, David↗
NASA NTRS1991

Propagation of high-energy laser beams through the earth's atmosphere II; Proceedings of the Meeting, Los Angeles, CA, Jan. 21-23, 1991

Consideration is given to turbulence at the inner scale, modeling turbulent transport in laser beam propagation, variable wind direction effects on thermal blooming correction, realistic wind effects on turbulence and thermal blooming compensation, wide bandwidth spectral measurements of atmospheric tilt turbulence, remote alignment of adaptive optical systems with far-field optimization, focusing infrared laser beams on targets in space without using adaptive optics, and a simplex optimization method for adaptive optics system alignment. Consideration is also given to ground-to-space multiline propagation at 1.3 micron, a path integral approach to thermal blooming, functional reconstruction predictions of uplink whole beam Strehl ratios in the presence of thermal blooming, and stability analysis of semidiscrete schemes for thermal blooming computation.

Ulrich, Peter B.↗