Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “SCAN”

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.

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

At least 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Scanning Angle Raman spectroscopy in polymer thin film characterization

The focus of this thesis is the application of Raman spectroscopy for the characterization of thin polymer films. Chapter 1 provides background information and motivation, including the fundamentals of Raman spectroscopy for chemical analysis, scanning angle Raman scattering and scanning angle Raman scattering for applications in thin polymer film characterization. Chapter 2 represents a published manuscript that focuses on the application of scanning angle Raman spectroscopy for the analysis of submicron thin films with a description of methodology for measuring the film thickness and location of an interface between two polymer layers. Chapter 3 provides an outlook and future directions for the work outlined in this thesis. Appendix A, contains a published manuscript that outlines the use of Raman spectroscopy to aid in the synthesis of heterogeneous catalytic systems. Appendix B and C contain published manuscripts that set a foundation for the work presented in Chapter 2.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Analysis of the effect of spherical aberrations on a solenoid scan

Solenoid scans are often used to determine the beam emittance of an intense relativistic electron beam (IREB). In a solenoid scan, the beam size is measured at a location downstream of the solenoid as a function of the strength of the solenoid magnetic field. The emittance is then inferred using a beam optics model of the transport of the beam through the solenoid magnet to the imaging location. This requires precise knowledge of the field strength and shape as a function of the current supplied to the solenoid. The beam optics model for an IREB needs to include an accurate model of the magnetic field. Unfortunately, most beam optics models do not include the effect of spherical aberrations which are inherent in a solenoid magnet. Spherical aberrations are manifested as an essentially quadratic increase in the solenoid magnetic field as a function of radius. One consequence of this is that the focal length will be dependent on the beam radius. This note examines the sensitivity of a typical solenoid scan performed on DARHT axis 2 to spherical aberrations. The sensitivity to spherical aberrations is examined as a function of the beam envelope size and the drift distance from the solenoid magnet to the imaging station.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Effective ZDC cross section derived from Vernier Scans during the RHICf run with polarized protons at 255 GeV in 2017

At RHIC the collision rate per IP is measured by the Zero Degree Calorimeters (ZDC). The collision rate, as measured by the ZDC, corresponds to the rate of mutual forward neutral particles above a variable threshold and within a certain coincidence window. During run 17 the detector was operated for the RHICf experiment in a slightly different configuration from the earlier standard polarized proton run. Due to the different configuration the ZDC detector was calibrated for the rhicf setup by performing a set of dedicated vernier scans. A total of 9 vernier scans were performed. This note presents the data and summarizes the results, i.e. effective ZDC cross section from those scans for the rhicf running period.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

H420 Imager Calibration Procedure: Field of View Scan

Gamma-ray imagers with coded apertures have a finite field of view (FOV) within which an image of a source can be generated. A “FOV scan” is a facet of imager calibration procedure that involves collecting specialized data for a range of source locations filling the FOV in order to understand and correct for differences in imager performance. Systematic distortions reveal relative displacements between internal imager components, which can be accounted for in data analysis. The success of this scan requires a stable imager position during the full measurement duration (~hours). This document summarizes the hardware and software tools required to conduct a FOV calibration scan of an H3D H420 Coded Aperture Gamma-Ray Imager.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

WREF Halo Streamline scanning lidar / Derived data / RHI

This dataset contains streamwise velocity retrieved from the Range Height Indicator (RHI) scans done by the UC Davis scanning Lidar. The quality control of the radial wind speed is performed following the algorithm of Beck & Kuhn (2017). Instantaneous realizations characterized by wind misalignment greater than 60 degrees (based on the closest VAD scan in time) are discarded.

17 WIND ENERGY↗
DOE OSTI2019

GPR Imaging for Deeply Buried Objects: A Comparative Study Based on Compositing of Scanning Frequencies and a Chirp Excitation Function

Compositing of ground penetrating radar (GPR) scans of differing frequencies have been found to produce cleaner images at depth using the Gaussian mixture model (GMM) feature of the expectation-maximization (EM) algorithm. GPR scans at various heights (“Stand Off”), as well as ground-based scans, have been studied. In this paper, we compare the GPR response from a chirp excitation function-based radar with the response from the EM GMM algorithm compositing process, using the same mix of frequencies. A chirp excitation pulse was found to be effective in delineating the defined buried object, but the resulting image is less sharp than the GMM EM method.

58 GEOSCIENCES↗
DOE OSTI2025

Realistic Noise Generation to Enhance Realism of Virtual Lidar Scans

Many real-world phenomena corrupt light detection and ranging (lidar) measurements, such as laser energy attenuation, variations in aerosol concentration and composition with height, and hard target returns. Accurate studies of lidar scans using virtual lidar methods should include some realistic model of these corrupting effects to generate more realistic simulations of lidar scans. We present a simple model that characterizes noise caused by energy attenuation and aerosol stratification. The model requires limited inputs and is developed for a Halo Photonics Streamline XR lidar but is readily generalizable for other lidar systems. A critical component of this model is a model of the standard deviation of measured wind speed as a function of the backscattered signal’s signal-to-noise ratio. We derive a general model for this behavior that can be adapted to different scan settings.

17 WIND ENERGY↗
DOE OSTI2017

Vertical profiles of the 3-D wind velocity retrieved from multiple wind lidars performing triple range-height-indicator scans

Abstract. Vertical profiles of 3-D wind velocity are retrieved from triple range-height-indicator (RHI) scans performed with multiple simultaneous scanning Doppler wind lidars. This test is part of the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) campaign carried out at the Boulder Atmospheric Observatory. The three wind velocity components are retrieved and then compared with the data acquired through various profiling wind lidars and high-frequency wind data obtained from sonic anemometers installed on a 300 m meteorological tower. The results show that the magnitude of the horizontal wind velocity and the wind direction obtained from the triple RHI scans are generally retrieved with good accuracy. However, poor accuracy is obtained for the evaluation of the vertical velocity, which is mainly due to its typically smaller magnitude and to the error propagation connected with the data retrieval procedure and accuracy in the experimental setup.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Tools for pressure core sub-coring and pore-scale micro-CT (computed tomography) scans

Abstract. The pore habits of gas hydrate in natural sediment matrices provide essential clues for understanding physical (mechanical, thermal, hydraulic, and electrical) properties of hydrate-bearing sediments, yet there are no tools that can directly visualize the pore habits of natural gas hydrate other than indirect interpretation based on core-scale or field-scale observations. A significant challenge is to obtain a mini-core from pressure cores retrieved from natural reservoirs for high-resolution micro-CT (computed tomography) scans while maintaining pressure and temperature conditions required for stability of gas hydrate during all operational steps including manipulation, cutting, transferring, sub-coring and CT scanning. We present a new set of tools for pore-scale micro-CT imaging of natural hydrate-bearing sediments while maintaining pressure and temperature control. The tests with laboratory-prepared cores and pressure cores successfully demonstrate the capability of this set of tools to subsample a mini-core from pressure cores, transfer the mini-core to an X-ray transparent core holder, and conduct micro-CT scans. Successfully obtained CT images prove the functionality of this set of tools.

Seol, Yongkoo↗
DOE OSTI2024

Influences of lidar scanning parameters on wind turbine wake retrievals in complex terrain

Abstract. Scanning lidars enable the collection of spatially distributed measurements of turbine wakes and the estimation of wake properties such as magnitude, extent, and trajectory. Lidar-based characterizations, however, may be subject to distortions due to the observational system. Distortions can arise from the resolution of the measurement points across the wake, the projection of the winds onto the beam, averaging along the beam probe volume, and intervening evolution of the flow over the scan duration. Using a large-eddy simulation and simulated measurements with a virtual lidar model, we assess how scanning lidar systems may influence the properties of the retrieved wake using a case study from the Perdigão campaign. We consider three lidars performing range-height indicator sweeps in complex terrain, based on the deployments of lidars from the Danish Technical University (DTU) and German Aerospace Center (DLR) at the Perdigão site. The unwaked flow, measured by the DTU lidar, is well-captured by the lidar, even without combining data into a multi-lidar retrieval. The two DLR lidars measure a waked transect from different downwind vantage points. In the region of the wake, the observation system reacts to the smaller spatial and temporal variations of the winds, allowing more significant observation distortions to arise. While the measurements largely capture the wake structure and trajectory over its 4–5 D extent, limited spatial resolution of measurement points and volume averaging lead to a quicker loss of the two lobes in the near wake, smearing of the vertical bounds of the wake (< 30 m), wake center displacements up to 10 m, and dampening of the maximum velocity deficit by up to a third. The virtual lidar tool, coupled with simulations, provides a means for assessing measurement capabilities in advance of measurement campaigns.

17 WIND ENERGY↗
DOE OSTI2020

Mini Micropulse Lidar measurements in vertical and scanning modes

The Atmospheric Radiation Measurement (ARM) program operates ten Sigma Space (currently Droplet Measurement Technologies/DMT) micropulse lidar systems (MPL-4B-IDS/POL-FS series), which detect the backscattered light in two orthogonal linear polarization channels allowing to distinguish between spherical (e.g. water) and non-spherical (e.g. ice) scattering particles. The ARM MPLs have been providing valuable measurements to the aerosol and cloud research community for well over a decade. DMT&rsquo;s Mini-Micropulse lidar (MiniMPL) is a compact version of the standard MPL. It reduces the power-aperture product to minimize cost, size, weight, power requirements and has all the electronics integrated with optics in a single box. Although as a result, it has a lower detection range than the MPL, limiting the measurements to the troposphere, its performance is promised to match that of the standard MPL within the troposphere. The MiniMPL weighs 13 kg, and the complete system, consisting of an optical transceiver and a laptop running the data acquisition and post-processing software, fits in a storm case, allowing its transport on domestic or international flights. This can be especially valuable for short field campaigns or Intensive Operational Periods, where time is of the essence when replacing a faulty instrument. In addition, the scanning polarization lidar capability (MiniMPL-SCAN option) could be of great interest for satisfying ARM measurement needs for certain research topics related to clouds and precipitation. To evaluate its full potential in comparison with co-located remote sensing instruments including the ARM MPL-4B-IDS/POL-FS at SGP, a miniMPL was hosted at the ARM Southern Great Plains (SGP) mega-site in 2020 for approximately 3 months. During this time the miniMPL was tested in both vertical sampling and scanning modes.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1963

Space astronomy and the slow-scan vidicon

Space astronomy is defined. In particular, the requirements for visual exploration of the Moon and Mars are outlined. The slow-scan vidicon is shown to be particularly useful as an astrophotographic instrument for space astronomy. The special instrumentation requirements for a slow-scan vidicon system are described for a Mars mission. Some of the techniques are illustrated with photos taken with a slow-scan vidicon system using as an optical objective the Mt. Wilson 60-in. telescope.

VIDICON↗
NASA NTRS1967

Design concept for improved photo-scan tube

Conceptual photo-scan tube avoids complexity of internal beam scanning and beam-current adjustment by optical scan readout. It differs from a conventional image orthicon in its use of an external oscilloscope tube.

Malling, L. R.↗
NASA NTRS1969

Multipurpose binocular scanning apparatus

Optical gimballing apparatus directs narrow fields of view throughout solid angle approaching 4 pi steradians. Image rotation produced by scanning can be eliminated or altered by gear trains directly linked to the scanning drive assembly. It provides the basis for a binocular scanning capability.

Chamberlain, F. R.↗
NASA NTRS1969

Electrooptical scanning of film

Scan-in scan-out flying spot scanning system recognizes three different levels of transmissivity within a frame. It selectively acts on these levels either to intensify the illumination or to extend the duration of the illuminating spot to any picture element. Thus it improves the ratio of signal to tube noise in the cameras output.

Billingsley, F. C.↗
NASA NTRS1971

Construction and testing of a Scanning Laser Radar (SLR), phase 2

The scanning laser radar overall system is described. Block diagrams and photographs of the hardware are included with the system description. Detailed descriptions of all the subsystems that make up the scanning laser radar system are included. Block diagrams, photographs, and detailed optical and electronic schematics are used to help describe such subsystem hardware as the laser, beam steerer, receiver optics and detector, control and processing electronics, visual data displays, and the equipment used on the target. Tests were performed on the scanning laser radar to determine its acquisition and tracking performance and to determine its range and angle accuracies while tracking a moving target. The tests and test results are described.

Flom, T.↗
NASA NTRS1973

Wide-field reflective scanning optical systems

Catoptric optical scanning system provides relatively fast line-scan rate for two-dimensional coverage. Rapid scan rates require low focal ratios between components and smallest possible masses. System is relatively free from monochromatic defects and chromatic aberrations.

Abel, I. R.↗