Search NASA⌕ Search

SEARCH · Search NASA

Results for “Scanning Control”

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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Suspension system for gimbal supported scanning payloads

Gimballed scanning devices or instruments are the subject of this invention. Scanning is an important aspect of space science. To achieve a scan pattern some means must be provided which impart to the payload an oscillatory motion. Various forms of machines have been employed for controllably conferring on scanning instruments predetermined scan patterns. They include control moment gyroscopes, reaction wheels, torque motors, reaction control systems, and the like. But rotating unbalanced mass (RUM) devices are a new and efficient way to generate scans in gimballed payloads. RUM devices are superior to previous scanning apparatus, but they require power consuming and frequently complex auxiliary control systems to position and reposition the particular scan pattern relative to a target or a number of targets. Herein the control system is simplified. The most frequently employed method for achieving the various scan patterns is to gimbal the scanning device. Gimbals are suspended in such a way that they can be activated to generate the scan pattern. The suspension means described is for payloads supported in gimbals wherein the payload rotation is restricted by a flex pivot so that the payload oscillates, thereby moving in a scan pattern.

Polites, Michael E.↗
NASA NTRS1973

Mass property control of a synchronous meteorological satellite scanning experiment.

A scanning mirror assembly which is part of a Synchronous Orbit Meteorological Satellite is an example where mission objectives required measurement and control of weight, mass center, principal moments of inertia, and products of inertia. The scanning mirror oscillates within the spin stabilized spacecraft, and both the scanning motor torque and perturbation of spacecraft attitude and spin rate have to be reduced to low levels. A theoretically ideal solution would be to make the mirror inertia constant about all axes in a plane perpendicular to the oscillation axis. A practically attainable compromise is to locate principal axes preferentially and make the difference between two of them acceptably small. Methods for making the necessary mass property measurements and deriving and applying minimum weight ballast correction to achieve the necessary mass distribution are discussed. It is noted that mass property control operations are typically subject to practical constraints such as geometry and functional operation of the system and capability of available measurement facilities and fixtures.

Lang, W. E.↗
DOE OSTI2020

Self-Assembly of Metallo-Supramolecules under Kinetic or Thermodynamic Control: Characterization of Positional Isomers Using Scanning Tunneling Spectroscopy

Coordination-driven self-assembly has been extensively employed to construct a variety of discrete structures as a bottom-up strategy. However, mechanistic understanding regarding whether self-assembly is under kinetic or thermodynamic control is less explored. To date, such mechanistic investigation has been limited to distinct, assembled structures. It still remains a formidable challenge to study the kinetic and thermodynamic behavior of self-assembly systems with multiple assembled isomers due to the lack of characterization methods. Herein, we use a stepwise strategy which combined self-recognition and self-assembly processes to construct giant metallo-supramolecules with 8 positional isomers in solution. With the help of ultrahigh-vacuum, low-temperature scanning tunneling microscopy and scanning tunneling spectroscopy, we were able to unambiguously differentiate 14 isomers on the substrate which correspond to 8 isomers in solution. Through measurement of 162 structures, the experimental probability of each isomer was obtained and compared with the theoretical probability. Finally, such a comparison along with density functional theory (DFT) calculation suggested that although both kinetic and thermodynamic control existed in this self-assembly, the increased experimental probabilities of isomers compared to theoretical probabilities should be attributed to thermodynamic control.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1986

Numerical pole assignment by eigenvalue Jacobian inversion

A numerical procedure for solving the linear pole placement problem is developed which operates by the inversion of an analytically determined eigenvalue Jacobian matrix. Attention is given to convergence characteristics and pathological situations. It is not concluded that the algorithm developed is suitable for computer-aided control system design with particular reference to the scan platform pointing control system for the Galileo spacecraft.

Sevaston, George E.↗
NASA NTRS1993

Effects of orbital exposure on RTV during the LDEF mission

Thermomechanical analysis (TMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were performed on samples of RTV 511 exposed on the Long Duration Exposure Facility (LDEF) mission for 6 years in orbit and unexposed RTV 511 control samples. Slices 20- to 400-microns thick were removed from the exposed surface down to a depth of 1,500 microns through the 3-mm thick samples. The TMA and DSC results, which arise from the entire slice and not just its surface, showed no significant differences between the LDEF exposed and the control samples. TMA scans were run from ambient to 500 C; results were compared by a tabulation of the onset temperatures for flow. DSC scans were run from ambient to 600 C; no endotherms or exotherms occurred over the range observed. What appear to be glass transition temperatures were compared for the samples as a function of section depth within the sample and between the exposed and control samples. The TGA scans from 25 to 900 C, which arise from the surface of the sample initially, showed a slight increase in the top most 105-micron slice (the exposed, discolored side) in the weight loss at 600 C in oxygen. This weight loss dropped to bulk values at the next slice below the top section, a mean depth of 258 microns. The control sample also showed an increase in weight loss as the top surface was approached, but the 600 C weight losses were very inconsistent. The LDEF RTV sample appears to be mechanically undamaged, with a surface layer which oxidizes slightly faster as a result of orbital exposure.

Brower, William E., Jr.↗
NASA NTRS1965

Advanced scan platform

Open and closed-loop actuation and electronic control mechanism for advanced scan platform

SERVOACTUATOR↗
DOE OSTI2023

Atomic force microscopy and scanning electron microscopy characterization of the controlling of surface morphology of epoxy‐amine‐cured spin‐coated films

Abstract Atomic force microscopy (AFM) was successfully used to study spin‐coated, amine‐cured epoxy film microstructure and morphology. The air‐epoxy and epoxy‐substrate interfaces were examined using tapping‐mode height and phase imaging AFM. The impact of relative humidity on the morphology and microstructure of the surfaces was determined. AFM was able to elucidate the changes on the surface as relative humidity during processing increased. It was observed that large nodular formations formed on the epoxy surface expose to the air but not epoxy surface formed on the substrate in addition to varying regions of more or less compliant structures, which was attributed to carbamate formation caused by the amine curing agent reaction with atmospheric CO 2 . Scanning electron microscopy (SEM) was used to further elucidate interface and interphase morphology of spin‐coated epoxies. Experimentation also demonstrated that post‐curing above the glass transition did not change the morphology structure, suggesting surface structures are “locked‐in.” SEM was used to further elucidate how the interface and interphase change with changing environmental conditions at both the air‐epoxy and epoxy‐substrate interface/interphases, including the impact of atmospheric CO 2 on Marangoni cell formation.

Shenk, Timothy M.↗
NASA NTRS1988

Direct control and characterization of a Schottky barrier by scanning tunneling microscopy

Scanning tunneling microscopy (STM) methods are used to directly control the barrier height of a metal tunnel tip-semiconductor tunnel junction. Barrier behavior is measured by tunnel current-voltage spectroscopy and compared to theory. A unique surface preparation method is used to prepare a low surface state density Si surface. Control of band bending with this method enables STM investigation of semiconductor subsurface properties.

Bell, L. D.↗
NASA NTRS1994

Results of a laboratory experiment that tests rotating unbalanced-mass devices for scanning gimbaled payloads and free-flying spacecraft

Rotating unbalanced-mass (RUM) devices are a new way to scan space-based, balloon-borne, and ground-based gimbaled payloads, like x-ray and gamma-ray telescopes. They can also be used to scan free-flying spacecraft. Circular scans, linear scans, and raster scans can be generated. A pair of RUM devices generates the basic scan motion and an auxiliary control system using torque motors, control moment gyros, or reaction wheels keeps the scan centered on the target and produces some complementary motion for raster scanning. Previous analyses and simulation results show that this approach offers significant power savings compared to scanning only with the auxiliary control system, especially with large payloads and high scan frequencies. However, these claims have never been proven until now. This paper describes a laboratory experiment which tests the concept of scanning a gimbaled payload with RUM devices. A description of the experiment is given and test results that prove the concept are presented. The test results are compared with those from a computer simulation model of the experiment and the differences are discussed.

Alhorn, D. C.↗
NASA NTRS1994

Rotating Unbalanced-Mass devices for scanning: Results from the proof-of-concept test

Rotating unbalanced-mass (RUM) devices are a new way to scan space-based, balloon-borne, and ground-based gimbaled payloads, like x-ray and gamma-ray telescopes. They can also be used to scan free-flying spacecraft. Circular scans, linear scans, and raster scans can be generated. A pair of RUM devices generates the basic scan motion and an auxiliary control system using torque motors, control moment gyros, or reaction wheels keeps the scan centered on the target and produces some complementary motion for raster scanning. Previous analyses and simulation results show that this approach offers significant power savings compared to scanning only with the auxiliary control system, especially with large payloads and high scan frequencies. However, these claims have never been proven until now. This paper describes a laboratory experiment which tests the concept of scanning a gimbaled payload with RUM devices. The test results are compared with those from a computer simulation model of the experiment and the differences are discussed.

Alhorn, Dean C.↗
DOE OSTI2026

FC Site 4.0 - NLR Scanning Lidar (Halo XR+ 235) / Standardized and Quality-Controlled Data

This dataset contains lidar data that have been standardized and quality-controlled through NatLabRockies/FIEXTA/LiDARGO (https://github.com/NatLabRockies/FIEXTA/tree/main/lidargo). Standardization rearranges the lidar data into convenient range vs beamID vs scanID coordinates that facilitate data analysis. The scan geometry (i.e., azimuth, elevation) is shifted on a regular grid based on the most likely angles within the scan file. Quality control of radial wind speed is performed through a generalized version of the dynamic lidar filter (Beck and Kuhn, 2017).

17 WIND ENERGY↗
DOE OSTI2026

FC Site 4.2 - NLR Scanning Lidar (Halo XR+ 199) / Standardized and Quality-Controlled Data

This dataset contains lidar data that have been standardized and quality-controlled through NatLabRockies/FIEXTA/LiDARGO (https://github.com/NatLabRockies/FIEXTA/tree/main/lidargo). Standardization rearranges the lidar data into convenient range vs beamID vs scanID coordinates that facilitate data analysis. The scan geometry (i.e., azimuth, elevation) is shifted on a regular grid based on the most likely angles within the scan file. Quality control of radial wind speed is performed through a generalized version of the dynamic lidar filter (Beck and Kuhn, 2017).

17 WIND ENERGY↗
DOE OSTI2026

FC Site 1.9 - NLR Scanning Lidar (Halo XR+ 200) / Standardized and Quality-Controlled Data

This dataset contains lidar data that have been standardized and quality-controlled through NatLabRockies/FIEXTA/LiDARGO (https://github.com/NatLabRockies/FIEXTA/tree/main/lidargo). Standardization rearranges the lidar data into convenient range vs beamID vs scanID coordinates that facilitate data analysis. The scan geometry (i.e., azimuth, elevation) is shifted on a regular grid based on the most likely angles within the scan file. Quality control of radial wind speed is performed through a generalized version of the dynamic lidar filter (Beck and Kuhn, 2017).

17 WIND ENERGY↗
NASA NTRS1993

Techniques used for the analysis of oculometer eye-scanning data obtained from an air traffic control display

The methodology and techniques used to collect and analyze look-point position data from a real-time ATC display-format comparison experiment are documented. That study compared the delivery precision and controller workload of three final approach spacing aid display formats. Using an oculometer, controller lookpoint position data were collected, associated with gaze objects (e.g., moving aircraft) on the ATC display, and analyzed to determine eye-scan behavior. The equipment involved and algorithms for saving, synchronizing with the ATC simulation output, and filtering the data are described. Target (gaze object) and cross-check scanning identification algorithms are also presented. Data tables are provided of total dwell times, average dwell times, and cross-check scans. Flow charts, block diagrams, file record descriptors, and source code are included. The techniques and data presented are intended to benefit researchers in other studies that incorporate non-stationary gaze objects and oculometer equipment.

Crawford, Daniel J.↗
DOE OSTI2026

Autonomous fabrication of tailored defect structures in 2D materials using machine learning-enabled scanning transmission electron microscopy

Materials with tailored quantum properties can be engineered from atomic-scale assembly techniques, but existing methods often lack the agility and accuracy to precisely and intelligently control the manufacturing process. Here, we demonstrate a fully autonomous approach for fabricating atomic-level defects using electron beams in scanning transmission electron microscopy (STEM) that combines advanced machine learning and automated beam control. As a proof of concept, we achieved controlled fabrication of MoS-nanowire (MoS-NW) edge structures by iterative and targeted exposure of MoS 2 monolayer to a focused electron beam to selectively eject sulfur atoms, utilizing high-angle annular dark-field (HAADF) imaging for feedback-controlled monitoring of structural evolution of defects. A machine learning framework combining a random forest model and a convolutional neural network (CNN) was developed to decode the HAADF image and accurately identify atomic positions and species. This atomic-level information was then integrated into an autonomous decision-making platform, which applied predefined fabrication strategies to instruct beam control about atomic sites to be ejected. The selected sites were subsequently exposed to a localized electron beam using an FPGA-controlled scan routine with precise control over beam positioning and duration. While the MoS-NW edge structures produced exhibit promising mechanical and electronic properties, the proposed methods to build the autonomous fabrication framework is material-agnostic and can be extended to other 2D materials for the creation of diverse defect structures and heterostructures beyond Mo S2 .

Engineering↗
NASA NTRS1984

Recent developments in monolithic phase-locked semiconductor laser arrays

Coherent combination of the power of several semiconductor lasers fabricated on the same substrate has been the subject of an intense research effort in recent years, the main motivation being to obtain higher power levels than those available from a single laser in a stable radiation pattern. Best results reported so far include 2.6 Watts CW emitted power and less than 1 deg far-field angle (in the array plane) in arrays where all the lasers are electrically connected in parallel. A different type of coherent array, where each element has a separate contact, has been recently demonstrated. While requiring the more complex two-level metallization technology, applying a separate contact to each laser provides an additional degree of freedom in the design and the operation of monolithic arrays. The separate contacts can be employed to tailor the near-field and far-field distributions and to compensate for device-to-device nonuniformities. Furthermore, the control of the currents of the array elements allows the performance of a variety of other functions, such as beam scanning, spectral mode control, wavelength tuning and control of the mutual coherence between array elements.

Katz, J.↗