Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Optical flow”

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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Three-dimensional visualization and display technologies; Proceedings of the Meeting, Los Angeles, CA, Jan. 18-20, 1989

Special attention was given to problems of stereoscopic display devices, such as CAD for enhancement of the design process in visual arts, stereo-TV improvement of remote manipulator performance, a voice-controlled stereographic video camera system, and head-mounted displays and their low-cost design alternatives. Also discussed was a novel approach to chromostereoscopic microscopy, computer-generated barrier-strip autostereography and lenticular stereograms, and parallax barrier three-dimensional TV. Additional topics include processing and user interface isssues and visualization applications, including automated analysis and fliud flow topology, optical tomographic measusrements of mixing fluids, visualization of complex data, visualization environments, and visualization management systems.

Robbins, Woodrow E.↗
NASA NTRS1990

Mass and energy flow in prominences

Mass and energy flow in quiescent prominences is considered based on the hypothesis that active region prominences have a different structure and thus different mass and energy flow characteristics. Several important physical parameters have been plotted using the computational model, representing the evolutionary process after the prominence formation. The temperature, velocity, conductive flux, and enthalpy flux are plotted against distance from the highest point in the loop to the coolest part of the prominence. It is shown that the maximum velocity is only about 5 km/s. The model calculations indicate that the transition region of prominences is dominated by complex processes. It is necessary to take into account mass flow at temperatures below 200,000 K, and both mass flow and optical depth effects in hydrogen at temperatures below 30,000 K. Both of these effects lead to a less steep temperature gradient through the prominence corona interface than can be obtained from the conduction alone.

Poland, Arthur I.↗
NASA NTRS1991

Passive range sensor refinement using texture and segmentation

Electrooptical sensors provide a covert way of computing range during helicopter flight. The optical flow-based computation of range provides range information only in certain distinguishable parts of the image. The regions where range information is available can be increased by performing texture analysis and object segmentation in the image. This paper reviews some of the literature on texture segmentation methods with a view towards applying them to images containing both man-made and natural objects at varying ranges. Two algorithmic approaches are given and their application to a real image is demonstrated. Results indicate that it will be necessary to combine several different texture measures and methods in a hierarchical way in order to achieve an object segmentation which is useful in enhancing range information.

Sridhar, Banavar↗
NASA NTRS1994

The effects of turbulence on droplet drag and secondary droplet breakup

The objective of this research is to obtain an improved understanding of the behavior of droplets in vaporizing sprays, particularly under conditions typical of those in high pressure rocket sprays. Experiments are conducted in a variety of high pressure, high temperature, optically-accessible flow systems, including one which is capable of operation at pressures up to 70 atm, temperatures up to 600 K, gas velocities up to 30 m/sec and turbulence intensities up to 40 percent. Single droplets, 50 to 500 micron in diameter, are produced by an aerodynamic droplet generator and transversely injected into the flow. Measurements are made of the droplet position, size, velocity and temperature and of the droplet's vapor wake from which droplet drag, dispersion, heating, vaporization and breakup are characterized.

Song, Y.-H.↗
NASA NTRS2004

RTO Technical Publications: A Quarterly Listing

The titles of five reports are listed here, together with an abstract for each. The titles include: 1) 'Spectral Models of Kuiper Belt Objects and Centaurs'; 2) 'Simulation of and for Military Decision Making'; 3) 'Abundance of the Radioactive Be-10 in the Cosmic Radiation up to 2 GeV/nucleon with the Balloon-borne Instrument ISOMAX1998'; 4) 'Optical Air Flow Measurements in Flight'; 5) 'Flight Test Measurement Techniques for Laminar Flow'.

Source record↗
NASA NTRS2002

Motor scaling by viewing distance of early visual motion signals during smooth pursuit

The geometry of gaze stabilization during head translation requires eye movements to scale proportionally to the inverse of target distance. Such a scaling has indeed been demonstrated to exist for the translational vestibuloocular reflex (TVOR), as well as optic flow-selective translational visuomotor reflexes (e.g., ocular following, OFR). The similarities in this scaling by a neural estimate of target distance for both the TVOR and the OFR have been interpreted to suggest that the two reflexes share common premotor processing. Because the neural substrates of OFR are partly shared by those for the generation of pursuit eye movements, we wanted to know if the site of gain modulation for TVOR and OFR is also part of a major pathway for pursuit. Thus, in the present studies, we investigated in rhesus monkeys whether initial eye velocity and acceleration during the open-loop portion of step ramp pursuit scales with target distance. Specifically, with visual motion identical on the retina during tracking at different distances (12, 24, and 60 cm), we compared the first 80 ms of horizontal pursuit. We report that initial eye velocity and acceleration exhibits either no or a very small dependence on vergence angle that is at least an order of magnitude less than the corresponding dependence of the TVOR and OFR. The results suggest that the neural substrates for motor scaling by target distance remain largely distinct from the main pathway for pursuit.

Non-NASA Center↗
NASA NTRS2015

Molecular-Based Optical Diagnostics for Hypersonic Nonequilibrium Flows

This presentation package consists of seven different talks rolled up into one. These talks are all invited orals presentations in a special session at the Aviation 2015 conference and represent contributions that were made to a recent AIAA book that will be published entitled 'Hypersonic Nonequilibrium Flows: Fundamentals and Recent Advances'. Slide 5 lists the individual presentations that will be given during the special session.

Paul Danehy↗
NASA NTRS2017

Recent Developments in X-Ray Diagnostics for Cryogenic and Optically Dense Coaxial Rocket Sprays

The mixing and atomization of propellants is often characterized by optically dense flow fields and complex breakup dynamics. In the development of propulsion systems, the complexity of relevant physics and the range of spatio-temporal scales often makes computational simulation impractical for full scale injector elements; consequently, continued research into improved systems for experimental flow diagnostics is ongoing. One area of non-invasive flow diagnostics which has seen widespread growth is using synchrotron based x-ray diagostics. Over the past 3 years, a series of water and cryogenic based experiments were performed at the Advanced Photon Source, Argonne National Lab, on a NASA in-house designed swirl co-axial rocket injector, designed for operation using liquid oxygen and liquid methane in support of Project Morpheus. A range of techniques, such as x-ray fluorescence and time-averaged radiography were performed providing qualitative and quantitative mass and phase distributions, and were complemented by investigations using time-resolved radiography and white beam imaging, which provided information on breakup and mixing dynamics. Results of these investigations are presented, and conclusions regarding the viability of x-ray based diagnostics are discussed.

Radke, Christopher D.↗
NASA NTRS1988

Optical, ultraviolet, and infrared observations of cooling flows in rich clusters

Many rich clusters are now known to possess centrally located optically emitting gas systems, which accompany large inflows of cooling cluster gas. Recent results of optical, UV, and IR studies on cooling flow clusters are reported which center on three topics: (1) spectroscopic studies of the velocity structure of the line-emitting gas systems, which are used to probe the dynamics of the central cluster regions; (2) filter imaging studies of cluster emission line systems, which have yielded line luminosities and characteristic angular scales; and (3) the results of combining this optical survey with similar surveys undertaken using ultraviolet and infrared satellite data. Carefully flux-calibrated data from this multiwavelength data base have been used to show that a small but significant component of dust extinction is associated with the environment of these clusters.

Hu, Esther M.↗
DOE OSTI2017

Synchrotron X-Ray Interrogation of Turbulent Gas–Liquid Mixing in Cryogenic Rocket Sprays

The atomization and vaporization of liquid jets within turbulent gaseous flows are characterized by the mixing phenomena occurring over a wide range of spatiotemporal scales. This creates a complex, turbid medium that is not easily interrogated using conventional optical-measurement techniques. In the current study, the optically dense, multiphase flow created by a cryogenic liquid jet injected into a turbulent gaseous coflow is probed using high-speed (MHz) X-ray radiography from a focused, narrowband synchrotron source to resolve the internal cascade of scales and the evolution to isotropic, homogeneous turbulence. Changes in the spectral characteristics for different flow conditions are furthermore correlated with changes in the spatial distributions of the liquid and gas phases within the spray using simultaneous X-ray radiography and tracer (krypton) fluorescence. It is found that an increase in entrainment and mixing infers an evolution in spectral characteristics toward the well-known -5/3 law of energy dissipation in the context of the classical Kolmogorov theory. Finally, these data demonstrate the utility of the synchrotron-based X-ray radiography and fluorescence for uncovering the internal, turbulent mixing processes in multiphase and optically dense flows.

42 ENGINEERING↗
NASA NTRS2003

Optical and Probe Diagnostics Applied to Reacting Flows

The general theme of the research my NASA colleague and I have planned is "Optical and probe diagnostics applied to reacting flows". We plan to explore three major threads during the fellowship period. The first interrogates the flame synthesis of carbon nanotubes using aerosol catalysts. Having demonstrated the viability of the technique for nanotube synthesis, we seek to understand the details of this reacting system which are important to its practical application. Laser light scattering will reveal changes in particle size at various heights above the burner. Analysis of the flame gas by mass spectroscopy will reveal the chemical composition of the mixture. Finally, absorption measurements will map the nanotube concentration within the flow. The second thread explores soot oxidation kinetics. Despite the impact of soot on engine performance, fire safety and pollution, models for its oxidation are inhibited by uncertainty in the values of the oxidation rate. We plan to employ both optical and microscopic measurements to refine this rate. Cavity ring-down absorption measurements of the carbonaceous aerosol can provide a measure of the mass concentration with time and, hence, an oxidation rate. Spectroscopic and direct probe measurements will provide the temperature of the system needed for subsequent modeling. These data will be benchmarked against changes in soot nanostructures as revealed by transmission electron microscopic images from directly sampled material.

Ticich, Thomas M.↗
DOE OSTI2018

Rational Evaluation and Cycle Life Improvement of Quinone-Based Aqueous Flow Batteries Guided by In-Line Optical Spectrophotometry

We measure electrolyte concentration and state-of-charge in real time in an operating aqueous anthraquinone-based flow battery using in-line optical spectrophotometry. By capitalizing on the linear transition in absorption spectra between oxidized and reduced states, we show how discontinuous capacity fade rates in redox flow batteries can be caused by a transition from one capacity-limiting electrolyte to the other, which is caused by reactant crossover. With this insight, we demonstrate an electrolyte-balancing scheme, which can be broadly applicable to flow battery systems with asymmetric electrolyte crossover rates.

25 ENERGY STORAGE↗
NASA NTRS2006

Supersonic Flow Field Investigation Using a Fiber-optic based Doppler Global Velocimeter

A three-component fiber-optic based Doppler Global Velocimeter was constructed, evaluated and used to measure shock structures about a low-sonic boom model in a Mach 2 flow. The system was designed to have maximum flexibility in its ability to measure flows with restricted optical access and in various facilities. System layout is described along with techniques developed for production supersonic testing. System evaluation in the Unitary Plan Wind Tunnel showed a common acceptance angle of f4 among the three views with velocity measurement resolutions comparable with free-space systems. Flow field measurements of shock structures above a flat plate with an attached ellipsoid-cylinder store and a low-sonic boom model are presented to demonstrate the capabilities of the system during production testing.

Meyers, James F.↗
NASA NTRS1984

Imaging Fluid Flow

Electro-optical system allows simultaneous viewing of schlieren, shadowgraph and interferometric images of volume of fluid under test. In imaging system cube beam splitters replaced by plate-type beam splitters or pellicle beam splitters.

Witherow, W. K.↗
NASA NTRS1995

High data density temperature measurement for quasi steady-state flows

A new optical instrument, the liquid crystal point diffraction interferometer (LCPDI), is used to measure the temperature distribution across a heated chamber filled with silicone oil. Data taken using the LCPDI are compared to equivalent measurements made with a traversing thermocouple and the two data sets show excellent agreement This instrument maintains the compact, robust design of Linnik's point diffraction interferometer and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction.

Mercer, Carolyn R.↗