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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 OSTI2024

Non-resonant Bragg scattering four-wave mixing at near-visible wavelengths in low-confinement silicon nitride waveguides

Quantum state coherent frequency conversion processes—such as Bragg-scattering four-wave mixing (BSFWM)—hold promise as a flexible technique for networking heterogeneous and distant quantum systems. In this Letter, we demonstrate BSFWM within an extended (1.2-m) low-confinement silicon nitride waveguide and show that this system has the potential for near-unity frequency conversion in visible and near-visible wavelength ranges. Using sensitive classical heterodyne laser spectroscopy at low optical powers, we characterize the Kerr coefficient (∼1.55 W −1 m −1 ) and linear propagation loss (∼0.0175 dB/cm) of this non-resonant waveguide system, revealing a record-high nonlinear figure of merit (NFM = γ / α ≈ 3.85 W −1 ) for BSFWM of near-visible light in non-resonant silicon nitride waveguides. We predict how, at high yet achievable on-chip optical powers, this NFM would yield a comparatively large frequency conversion efficiency, opening the door to near-unity flexible frequency conversion without cavity enhancement and resulting bandwidth constraints.

Jaber, Nicholas (ORCID:000900070106809X)↗
DOE OSTI2024

First search for an anomalous excess of charged-current $\nu_e$ interactions without visible pions using the full MicroBooNE dataset

This public note presents an investigation of low-energy electron-neutrino events in the Fermilab Booster Neutrino Beam by the MicroBooNE experiment. This search is motivated by the excess of low energy electromagnetic events observed by the MiniBooNE experiment and, more broadly, by the landscape of neutrino anomalies observed at short baselines. This is the first measurement to use all of the data collected by the MicroBooNE experiment, corresponding to $1.1\times 10^{21}$ protons on target. Two exclusive samples of electron neutrinos without visible pions are used, one with visible protons and one without any visible protons. MicroBooNE data is compared to two empirical models of the MiniBooNE low energy excess, one obtained by enhancing the electron-neutrino content as a function of the neutrino energy, and one representing the excess for the first time as a function of the kinematics of shower energy and angle. This measurement excludes an electron-like interpretation of the MiniBooNE excess based on these models at $\geq 99\%$ confidence level in all kinematic variables.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

MicroBooNE Electron Neutrino Cross Sections without Visible Pions

MicroBooNE is an 85-tonne liquid argon time projection chamber (LArTPC) at Fermilab. It collected data from two different beam lines between 2015 and 2020 and has since released a large number of neutrino cross section results on argon. These inform neutrino interaction modelling in view of next generation LArTPCs such as the upcoming DUNE experiment. We present new measurements of the electron neutrino charged current pionless cross section on argon in the MicroBooNE detector. These measurements are essential to DUNE’s oscillation analysis as they impact the predicted interaction rate of the main flavor appearance signal. Two measurements are presented, one that leverages the full on-axis MicroBooNE Booster Neutrino Beam dataset while the other uses about 30% of the 8° off-axis Neutrino at the Main Injector beam dataset. Two channels can be considered: with or without a visible pion in the final state. Both measurements consider events with visible protons and the BNB measurement also measures electron neutrinos across the proton visibility threshold. Differential cross sections are extracted in proton and electron kinematics. The relationship between the hadronic and leptonic systems is explored through the angle between the proton and electron directions. The resulting cross sections are compared to a variety of generator predictions using different models of neutrino interactions. We find overall good agreement with most models, especially in lepton kinematics.

Mellet, Lucile [Michigan State U.]↗
NASA NTRS1973

Visible infrared spin-scan radiometer

The visible infrared spin-scal radiometer (VISSR) may be considered as a camera system capable of simultaneously providing both visible and infrared earth and cloud cover pictures every 20 minutes from the geostationary synchronous meteorological satellite (SMS). With a 0.9-kilometer resolution in the visible spectrum and a 9-kilometer resolution in the IR spectrum, the VISSR/SMS SYSTEM makes its possible to study atmospheric dynamics through 24-hour continuous observation of cloud altitudes, patterns, motion, and temperature distributions.

Phenix, J. E.↗
NASA NTRS1975

Differences in visible and near-infrared light reflectance between orange fruit and leaves

The objective was to find the best time during the season (April 26, 1972 to January 8, 1973) to distinguish orange fruit from leaves by spectrophotometrically determining at 10-day intervals when the difference in visible (550- and 650-nm wavelengths) and near-infrared (850-nm wavelength) light reflectance between fruit and nearby leaves was largest. December 5 to January 8 was the best time to distinguish fruit from leaves. During this period the fruit's color was rapidly changing from green to yellow, and the difference in visible light reflectance between fruit and leaves was largest. The difference in near-infrared reflectance between leaves and fruit remained essentially constant during ripening when the difference in visible light reflectance between leaves and fruit was largest.

Gausman, H. W.↗
NASA NTRS1976

Calculation of the twilight visibility function of near-sun objects

The visibility function, defined here as the magnitude difference between the excess brightness of a given object and that of the background sky, of near-sun objects during twilight is obtained from a general calculation which considers the twilight sky background, atmospheric extinction, and night glow. Visibility curves are computed for a number of cases in which observations have been recorded, particularly that of comet Kohoutek. For this object, the computed visibility maxima agree well in time with the reported times of observation.

Kastner, S. O.↗
NASA NTRS1978

Summary report of the Visibility Committee

Problems related to visibility and some possible solutions are expressed. Automatic weather stations, aircrew education and training, slant range visibility, twelve airports planning, and designs for new runway guidance are discussed in improving visibility.

Gardner, R. L.↗
NASA NTRS1977

Driver steering dynamics measured in car simulator under a range of visibility and roadmaking conditions

A simulation experiment was conducted to determine the effect of reduced visibility on driver lateral (steering) control. The simulator included a real car cab and a single lane road image projected on a screen six feet in front of the driver. Simulated equations of motion controlled apparent car lane position in response to driver steering actions, wind gusts, and road curvature. Six drivers experienced a range of visibility conditions at various speeds with assorted roadmaking configurations (mark and gap lengths). Driver describing functions were measured and detailed parametric model fits were determined. A pursuit model employing a road curvature feedforward was very effective in explaining driver behavior in following randomly curving roads. Sampled-data concepts were also effective in explaining the combined effects of reduced visibility and intermittent road markings on the driver's dynamic time delay. The results indicate the relative importance of various perceptual variables as the visual input to the driver's steering control process is changed.

Allen, R. W.↗
NASA NTRS1980

Quasi-simultaneous observations of the BL Lac object MK 501 in X-ray, UV, visible, IR and radio frequencies

Quasi-simultaneous observations of the BL Lacertae (Lac) objects MK 501 were performed for the first time at X-ray, ultraviolet, visible, infrared, and radio frequencies. The observed spectral slope from the X-ray to UV regions is positive and continuous, but that from the mid UV to visible light region becomes gradually flat and possibly turns down toward lower frequencies; the optical radio emission can not be accounted for by a single power law. Several theoretical models were considered for the emission mechanism. A quantitative comparison was performed with the synchrotron-self-Compton model; the total spectrum is found consistent with this model. The spectrum from visible light to X-ray is consistent with synchrotron radiation or with inverse-Compton scattering by a hot thermal cloud of electrons. The continuity of the spectral slope from X-ray to UV implied by the current data suggests that the previous estimates of the total luminosity of this BL Lac object is underestimated by a factor of about three or four.

Kondo, D. M.↗
NASA NTRS1980

Assessment of the visibility impairment caused by the emissions from the proposed power plant at Boron, California

The current atmospheric conditions and visibility were modeled, and the effect of the power plant effluent was then added to determine its influence upon the prevailing visibility; the actual reduction in visibility being a function of meteorological conditions and observer-plume-target geometry. In the cases investigated, the perceptibility of a target was reduced by a minimum of 10 percent and a maximum of 100 percent. This significant visual impact would occur 40 days per year in the Edwards area with meteorological conditions such as to cause some visual impact 80 days per year.

Bergstrom, R. W.↗
NASA NTRS1981

Low-visibility visual simulation with real fog

An environmental fog simulation (EFS) attachment was developed to aid in the study of natural low-visibility visual cues and subsequently used to examine the realism effect upon the aircraft simulator visual scene. A review of the basic fog equations indicated that two major factors must be accounted for in the simulation of low visibility - one due to atmospheric attenuation and one due to veiling luminance. These factors are compared systematically by (1) comparing actual measurements to those computed from the fog equations, and (2) comparing runway-visual-range-related visual-scene contrast values with the calculated values. These values are also compared with the simulated equivalent equations and with contrast measurements obtained from a current electronic fog synthesizer to help identify areas in which improvements are needed. These differences in technique, the measured values, the features of both systems, a pilot opinion survey of the EFS fog, and improvements (by combining features of both systems) that are expected to significantly increase the potential as well as flexibility for producing a very high-fidelity low-visibility visual simulation are discussed.

Chase, W. D.↗
NASA NTRS1982

Analysis of driver performance under reduced visibility

Mathematical models describing vehicle dynamics as well as human behavior may be useful in evaluating driver performance and in establishing design criteria for vehicles more compatible with man. In 1977, a two level model of driver steering behavior was developed, but its parameters were identified for clear visibility conditions only. Since driver performance degrades under conditions of reduced visibility, e.g., fog, the two level model should be investigated to determine its applicability to such conditions. The data analysis of a recently performed driving simulation experiment showed that the model still performed reasonably well under fog conditions, although there was a degradation in its predictive capacity during fog. Some additional parameters affecting anticipation and lag time may improve the model's performance for reduced visibility conditions.

Kaeppler, W. D.↗
NASA NTRS1981

Images of Jupiter from the Pioneer 10 and Pioneer 11 Infrared Radiometers - A comparison with visible and 5-micron images

The images with geometric control which present Pioneer 10 and 11 Infrared Radiometer data aquired at Jupiter are compared with 5.0-micron and visible images taken in the same time frame. It is found that (1) at 5.0, 20 and 45 microns, the association of dark and light areas with warm and cool areas, respectively, extends to nearly all features observed on the planet; (2) where the normal association of light and dark visible markings with the zone velocity breaks down, the infrared emission seems to follow the visible cloud structure rather than the zonal velocity structure; and (3) exceptions to the general rule involve 20-micron radiation, which reflects conditions in the 0.1-0.3 bar altitude range. A comparison of Pioneer 10 and 11 images suggests that the South Equatorial Belt became brighter at 20 microns, yet remained constant at other wavelengths between the two encounters.

Orton, G. S.↗
NASA NTRS1984

A technique combining the visibility of a Doppler signal with the peak intensity of the pedestal to measure the size and velocity of droplets in a spray

A technique combining the visibility of a Doppler signal and the intensity of the scattered light to measure the size and velocity of particles is presented. It is shown that using only the visibility technique can lead to large errors under many conditions such as dense sprays. It is also shown that this error is considerably reduced and very high resolution is obtained by combining the visibility with the intensity of the scattered light. An instrument was developed using this new concept and measurements were performed in sprays of known characteristics. The results of monodispersed, bimodal and trimodal sprays are reported.

Hess, C. F.↗
NASA NTRS1984

An intercalibration of Meteosat-1 and GOES-2 visible and infrared measurements

An intercomparison between radiative parameters determined from visible and infrared channels of the Meteosat-1 and GOES-2 geosynchronous satellites has been carried out using data obtained over the central Atlantic Ocean for 5 November 1978. Hourly visible-infrared measurement pairs at a nominal resolution of 5 km (Meteosat) or 8 km (GOES) have been stored in 1 deg x 1 deg longitude-latitude regions. For the infrared intercomparisons, the GOES 11.5 micron radiance has been compared to Meteosat infrared counts. The scatter in partly cloudy regions is interpreted as being caused by meteorological differences arising from differences in measurement time between the two data sets. For the visible intercomparison, the GOES measurements for clear and cloudy scenes have first been converted with the aid of scene-dependent angular reflectance and albedo models to estimates of the filtered shortwave radiance that GOES would have measured had it been in the Meteosat position. This value has then been compared to Meteosat counts for the shortwave channel. The results indicate that earlier Meteosat calibrations made from airplane overflights of a limited variety of surfaces are applicable to much larger areas of cloud and ocean.

Brooks, D. R.↗
NASA NTRS1983

Observations of the earth using nighttime visible imagery

The earth as viewed from space in visible light at night reveals some features not easily discernible during the day such as aurora, forest fires, city lights and gas flares. In addition, those features having a high albedo such as snow and ice can be identified on many moonlit nights nearly as well as they can in sunlight. The Air Force DMSP satellites have been operating in the visible wavelengths at night since the mid 1960s. Most all other satellites having optical sensors are incapable of imaging at night. Imaging systems having improved light sensitivity in the visible portion of the spectrum should be considered when planning future earth resources satellite missions in order to utilize nighttime as well as daytime visual observations.

Foster, J. L.↗
NASA NTRS1984

Infrared and visible detector electronics for the Infrared Astronomical Satellite (IRAS)

The paper describes the detectors, preamplifiers, and processing electronics; the system characterization test methods and results; and the performance of the detectors and electronics during the first month of on-orbit operation of the IRAS telescope. The Focal Plane Array (FPA) consists of 62 IR channels and 8 visible channels operating at 2.5 K. The IR detectors are grouped in eight 7 or 8 channel staggered linear subarrays with shared bias voltage; the visible detectors are grouped in two 4 channel skewed arrays, also with shared bias. Each channel detector is dc coupled to a TIA preamplifier through a very low power thermally isolated JFET source follower operating at about 65 K within the FPA housing. The visible channel detectors are ac coupled to TIA preamplifiers and signal chain electronics using MOSFET source followers operating at about 2.5 K within the FPA housing. The detectors, preamplifiers, analog electronics, and grounding are discussed as they evolved and were implemented during FPA retrofit, telescope integration, and preparation for launch.

Langford, D. L.↗
NASA NTRS1985

Ordering actions for visibility

The notion of 'atomic actions' has been considered in recent work on data integrity and reliability. It has been found that the standard database operations of 'read' and 'write' carry with them severe performance limitations. For this reason, systems are now being designed in which actions operate on 'objects' through operations with more-or-less arbitrary semantics. An object (i.e., an instance of an abstract data type) comprises data, a set of operations (procedures) to manipulate the data, and a set of invariants. An 'action' is a unit of work. It appears to be primitive to its surrounding environment, and 'atomic' to other actions. Attention is given to the conventional model of nested actions, ordering requirements, the maximum possible visibility (full visibility) for items which must be controlled by ordering constraints, item management paradigms, and requirements for blocking mechanisms which provide the required visibility.

Mckendry, M. S.↗