SEARCH · Search NASA

Results for “object localization”

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.

SourceResearch connectionFrom yearThrough year

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

At least 181 records · Page 10

All sources NASA NTRS DOE OSTI

NASA NTRS1991

Physical processes in comets

Post-Halley comets are known to be irregular objects with most nucleus activity very localized and with the dust coma capable of fragmentation and apparently being a source of gas. Older, 1-D strategies which assume steady isotropic outflow of material can give poor time-and-space averaged results, at best. With 2-D data, images through interference filters, it is hoped that: dust structures can be seen that give evidence of the proper geometry for data reduction; gradients along the axes of symmetry and evidence of fragmentation can be studied; and that evidence for gas abundance gradients associated with the dust can be found. High quality data from brighter comets can then be used to suggest improved data reduction procedures for fainter ones. To obtain such data, large image-quality interference filters were procured for use with a charge coupled device (CCD) camera at Lick Observatory, where the scale of the 1 m Nickel reflector is ideal for brighter comets. Whenever possible, data is taken simultaneously with other telescopes and equipment, especially spectroscopy at the Lick 3 m or infrared photometry at the Infrared Telescope Facility (IRTF) on Mauna Kea.

Newburn, Ray L., Jr.↗

NASA NTRS1995

Effects of gravity on sheared and nonsheared turbulent nonpremixed flames

The present numerical study is concerned with the fundamental physics of the multiway interaction between turbulence, chemical reaction, and buoyancy in a nonpremixed flame. The method of direct numerical simulation (DNS) is used to solve the instantaneous, three-dimensional governing equations. Because of the present supercomputer limitations, we consider two simple flow geometries, namely an initially uniform flow without shear (equivalent to grid-generated turbulence) and an initially uniform shear flow. In each flow, the fuel and oxidant initially exist as two separate streams. As the reactants mix, chemical reaction takes place and exothermic energy is released causing variations in density. In the presence of a gravity field, the spatial and temporal distributions of the induced buoyancy forces depend on the local density gradients and the direction of the gravitational acceleration. The effects of buoyancy include the generation of local shear, baroclinic production or destruction of vorticity, and countergradient heat and mass transport. Increased vorticity and small-scale turbulence promote further mixing and reaction. However, if the strain-rates become too high, local flame extinction can occur. Our objective is to gain an understanding of the complex interactions between the physical phenomena involved, with particular attention to the effects of buoyancy on the turbulence structure, flame behavior, and factors influencing flame extinction.

Elghobashi, Said↗

NASA NTRS2001

Permeability Testing of Impacted Composite Laminates for Use on Reusable Launch Vehicles

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite, and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented, and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a nonlinear fashion for almost all the specimens tested.

Nettles, A. T.↗

NASA NTRS2001

Permeability Testing of Impacted Composite Laminates for Use on Reusable Launch Vehicles

Nettles, Alan T.↗

NASA NTRS2002

Permeability After Impact Testing of Composite Laminates

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

Nettles, A.T.↗

NASA NTRS2003

Permeability After Impact Testing of Composite Laminates

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

Nettles, Alan T.↗

NASA NTRS2015

Odyssey Mars Orbiter - Thirteen Years of On-Orbit Navigation

The Odyssey spacecraft has been in Mars orbit since October 24, 2001 and has nearly completed 61,490 orbits. Navigation operational objectives include the following: Control the local mean solar time for science observations; for most of the mission, this varied from 3:45 pm to 5:20 pm. Currently, an orbit trim maneuver planned for November 10, 2015 will place Odyssey at 6:45 pm/6:45 am at equator crossings in order to observe early morning ground frost, fog and clouds. Initially, Odyssey was late by 42 minutes for an over-flight of the critical seven minutes of Phoenix's entry, descent and landing (EDL). Odyssey was successfully positioned for this over-flight using the Delta V from angular momentum desaturations (AMD). Similar results for the Mars Science Laboratory's EDL and Comet Siding Spring's minimum risk location will be presented. Odyssey has and continues to relay significant quantities of rover data. Navigation successfully models frequent AMD Delta Vs in order to generate accurate sixty-day trajectory predictions; a typical timing error is 25 seconds after 60 days. However, unexpected events, such as safe-mode entries with their larger and more frequent thrusting, severely impact that trajectory accuracy. Impacted trajectories can have timing errors ranging from a few minutes to ten-to-fifteen minutes after sixty-days. Other analyses (briefly stated) include: a) the offset of the orbital ground track pattern after an initial cycle of 30 days or 362 orbits and b) an operations environment of continuous thrusting if/when one of the three remaining reaction wheels fails.

trajectory accuracy↗

NASA NTRS2023

Automated Fiber Placement Through Thickness Defect Stacking Optimization

In its 2022 commercial market outlook, Boeing forecasted an 80% increase in the global fleet through 2041 compared to 2019 pre-pandemic levels. This sharp rise in demand will drive pressure onto airframe manufacturers to ramp up production and find more efficient ways to design and manufacture airplanes. Complicating this challenge is the industry’s recent transformation from traditional metal-based airframes towards hybrid composite-metal aircraft. While composites have been used in aviation for decades, aircraft manufacturers are still struggling to design and manufacture quality parts at a high rate. Automated Fiber Placement (AFP) is one of the main manufacturing techniques used to produce large-scale composite parts. After a design has been created, a manufacturing strategy has to be developed based on the working material, part geometry, and machine capabilities. This process planning stage is essential to the AFP workflow and currently requires a high level of manual input from an experienced process planner. In an effort to automate and optimize this stage, the Computer Aided Process Planning (CAPP) module was developed. CAPP assists process planners in identifying optimal starting point location and layup strategy for each ply of a laminate. This Ply-Level Optimization (PLO) phase operates on the quantification of ply quality through predictable geometry-based defects such as gaps, overlaps, angle deviation, and steering. As you move from PLO to Laminate-Level Optimization (LLO) the design space grows exponentially, emphasizing the need for automated optimization. The work presented in this thesis expands CAPP’s functionality by comparing the planned fiber paths through the thickness of the laminate to mitigate stacked area defects and achieve an optimal laminate-level manufacturing strategy. Within CAPP, predicted gap and overlap defects are imported from Vericut Composites Programming (VCP) and then discretized to streamline the through-thickness comparison. Two objective functions are used to score different combinations of ply layup strategies based on defect stacking both globally and locally. Four combinatorial optimization algorithms were coupled with these objective functions to investigate the laminate-level manufacturing strategy design space and converge on the optimal plan. These algorithms were evaluated based on accuracy and efficiency through virtual testing on a complex tool surface. A separate LLO approach was developed to achieve near-optimal laminates in significantly less time. The end result is a software package which greatly reduces the required input from process planners, shortening the design-build cycle time and improving part quality.

AFP↗

NASA NTRS2000

Motion coherence affects human perception and pursuit similarly

Pursuit and perception both require accurate information about the motion of objects. Recovering the motion of objects by integrating the motion of their components is a difficult visual task. Successful integration produces coherent global object motion, while a failure to integrate leaves the incoherent local motions of the components unlinked. We compared the ability of perception and pursuit to perform motion integration by measuring direction judgments and the concomitant eye-movement responses to line-figure parallelograms moving behind stationary rectangular apertures. The apertures were constructed such that only the line segments corresponding to the parallelogram's sides were visible; thus, recovering global motion required the integration of the local segment motion. We investigated several potential motion-integration rules by using stimuli with different object, vector-average, and line-segment terminator-motion directions. We used an oculometric decision rule to directly compare direction discrimination for pursuit and perception. For visible apertures, the percept was a coherent object, and both the pursuit and perceptual performance were close to the object-motion prediction. For invisible apertures, the percept was incoherently moving segments, and both the pursuit and perceptual performance were close to the terminator-motion prediction. Furthermore, both psychometric and oculometric direction thresholds were much higher for invisible apertures than for visible apertures. We constructed a model in which both perception and pursuit are driven by a shared motion-processing stage, with perception having an additional input from an independent static-processing stage. Model simulations were consistent with our perceptual and oculomotor data. Based on these results, we propose the use of pursuit as an objective and continuous measure of perceptual coherence. Our results support the view that pursuit and perception share a common motion-integration stage, perhaps within areas MT or MST.

NASA Center ARC↗

NASA NTRS2011

Wake Cycle Robustness of the Mars Science Laboratory Flight Software

The Mars Science Laboratory (MSL) is a spacecraft being developed by the Jet Propulsion Laboratory (JPL) for the purpose of in-situ exploration on the surface of Mars. The objective of MSL is to explore and quantitatively assess a local region on the Martian surface as a habitat for microbial life, past or present. This objective will be accomplished through the assessment of the biological potential of at least one target environment, the characterization of the geology and geochemistry of the landing region, an investigation of the planetary process relevant to past habitability, and a characterization of surface radiation. For this purpose, MSL incorporates a total of ten scientific instruments for which functions are to include, among others, atmospheric and descent imaging, chemical composition analysis, and radiation measurement. The Flight Software (FSW) system is responsible for all mission phases, including launch, cruise, entry-descent-landing, and surface operation of the rover. Because of the essential nature of flight software to project success, each of the software modules is undergoing extensive testing to identify and correct errors.

Whitehill, Robert↗

NASA NTRS1995

Stereo-Based Region-Growing using String Matching

We present a novel stereo algorithm based on a coarse texture segmentation preprocessing phase. Matching is performed using a string comparison. Matching sub-strings correspond to matching sequences of textures. Inter-scanline clustering of matching sub-strings yields regions of matching texture. The shape of these regions yield information concerning object's height, width and azimuthal position relative to the camera pair. Hence, rather than the standard dense depth map, the output of this algorithm is a segmentation of objects in the scene. Such a format is useful for the integration of stereo with other sensor modalities on a mobile robotic platform. It is also useful for localization; the height and width of a detected object may be used for landmark recognition, while depth and relative azimuthal location determine pose. The algorithm does not rely on the monotonicity of order of image primitives. Occlusions, exposures, and foreshortening effects are not problematic. The algorithm can deal with certain types of transparencies. It is computationally efficient, and very amenable to parallel implementation. Further, the epipolar constraints may be relaxed to some small but significant degree. A version of the algorithm has been implemented and tested on various types of images. It performs best on random dot stereograms, on images with easily filtered backgrounds (as in synthetic images), and on real scenes with uncontrived backgrounds.

Mandelbaum, Robert↗

NASA NTRS1982

Faint-object spectrograph optical bench

The Faint-Object Spectrograph (FOS) is one of five scientific instruments under development for use with the Optical Telescope Assembly (OTA) of NASA's Space Telescope. It is a dual-channel spectrograph operating with two independent 512-channel pulse-counting Digicons. The FOS will be employed in connection with the study of scientific questions associated with quasars, active galaxies, normal distant and local group galaxies, a wide class of objects within the Milky Way Galaxy and neighboring galaxies, and objects within the solar system. The FOS contains an optical bench which supports all optical elements. Dimensional stability was the primary design requirement for the optical bench. This led to the selection of a graphite/epoxy structure using laminates with very low coefficients of thermal expansion and high stiffness. The technical requirements are considered and details of fabrication are discussed.

Toth, J. M., Jr.↗

NASA NTRSDate not supplied

MISTRAL: Concept and Analysis of Persistent Airborne Localization of GHG Emissions

In this study, we propose a concept for localizing and mitigating greenhouse gases and other emissions from areas of various sizes, using a multiscale, airborne localization fleet, supported by information from satellites. Our objective is a rapidly implementable capability for the reduction of atmospheric methane by empowering the communities in proximity to emissions to actively contribute to methane mitigation via fleet operations by local governments, first responders, and individuals . Fully autonomous operations are economically desirable and technically feasible now. However, the development of regulations for autonomous operations is in early stages. Since rapid impact is critical to reducing emissions, the concept starts with remotely controlled vehicles. As regulations for autonomous operations reach maturity, the concept can be easily transitioned from the remotely piloted to autonomous mode. We report on a preliminary system analysis of the concept. Localization of methane emissions from the Permian Basin oil and gas production site serves as the design reference mission; however, the airborne concept is applicable to a broad range of use cases, and we describe several in this analysis. We consider leveraging satellite and ground-based resources within the airborne concept of operations. The study analyses uninhabited aerial system localization operations under the most conservative assumptions on resources and available information. Even under these assumptions, the concept is shown to be viable for local community operations.

airborne methane localization↗

NASA NTRS2008

NASA Remote Sensing Applications for Archaeology and Cultural Resources Management

NASA's Earth Science Mission Directorate recently completed the deployment of the Earth Observation System (EOS) which is a coordinated series of polar-orbiting and low inclination satellites for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans. One of the many applications derived from EOS is the advancement of archaeological research and applications. Using satellites, manned and unmanned airborne platform, NASA scientists and their partners have conducted archaeological research using both active and passive sensors. The NASA Stennis Space Center (SSC) located in south Mississippi, near New Orleans, has been a leader in space archaeology since the mid-1970s. Remote sensing is useful in a wide range of archaeological research applications from landscape classification and predictive modeling to site discovery and mapping. Remote sensing technology and image analysis are currently undergoing a profound shift in emphasis from broad classification to detection, identification and condition of specific materials, both organic and inorganic. In the last few years, remote sensing platforms have grown increasingly capable and sophisticated. Sensors currently in use, including commercial instruments, offer significantly improved spatial and spectral resolutions. Paired with new techniques of image analysis, this technology provides for the direct detection of archaeological sites. As in all archaeological research, the application of remote sensing to archaeology requires a priori development of specific research designs and objectives. Initially targeted at broad archaeological issues, NASA space archaeology has progressed toward developing practical applications for cultural resources management (CRM). These efforts culminated with the Biloxi Workshop held by NASA and the University of Mississippi in 2002. The workshop and resulting publication specifically address the requirements of cultural resource managers through the use of remote sensing. In 2007, NASA awarded six competitively chosen projects in Space Archaeology through an open solicitation whose purpose, among several, was to addresses the potential benefits to modern society that can be derived through a better understanding of how past cultures succeeded or failed to adapt to local, regional, and global change. A further objective of NASA's space archaeology is the protection and preservation of cultural heritage sites while planning for the sustainable development of cultural resources. NASA s archaeological approach through remote sensing builds on traditional methods of aerial archaeology (i.e. crop marks) and utilizes advanced technologies for collecting and analyzing archaeological data from digital imagery. NASA s archaeological research and application projects using remote sensing have been conducted throughout the world. In North America, NASA has imaged prehistoric mound sites in Mississippi; prehistoric shell middens in Louisiana, Puebloan sites in New Mexico and more recently the sites associated with the Lewis and Clark Corps of Discovery Expedition (1804-1806). In Central America, NASA archaeologists have researched Mayan sites throughout the region, including the Yucatan and Costa Rica, as well as Olmec localities in Veracruz. Other data has been collected over Angkor, Cambodia, Giza in Egypt, the lost city of Ubar on the Arabian Peninsula.

Giardino, Marco J.↗

NASA NTRS1993

The role of visual context in manual target localization

During space flight and immediately after return to the 1-g environment of earth, astronauts experience perceptual and sensory-motor disturbances. These changes result from adaptation of the astronaut to the microgravity environment of space. During space flight, sensory information from the eyes, limbs, and vestibular organs is reinterpreted by the central nervous system in order to produce appropriate body movements in the microgravity. This adaptation takes several days to develop. Upon return to earth, the changes in the sensory-motor system are no longer appropriate to a 1-g environment. Over several days, the astronaut must re-adapt to the terrestrial environment. Alterations in sensory-motor function may affect eye-head-hand coordination and, thus, the crewmember's ability to manually locate objects in extrapersonal space. Previous reports have demonstrated that crewmembers have difficulty in estimating joint and limb position and in pointing to memorized target positions on orbit and immediately postflight. The ability to point at or reach toward an object or perform other manual tasks is essential for safe Shuttle operation and may be compromised particularly during re-entry and landing sequences and during possible emergency egress from the Shuttle. An understanding of eye-head-hand coordination and the changes produced during space flight is necessary to develop effective countermeasures. This summer's project formed part of the study of the sensory cues use in the manual localization of objects.

Barry, Susan R.↗

NASA NTRS2008

Mini-Survey Of SDSS of [OIII] AGN With Swift

The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. Recent work (e.g. Ferrarese and Merritt 2000) strongly suggests every massive galaxy has a central black hole. However, most of these objects either are not radiating or have been very difficult to detect. We are now in the era of large surveys, and the luminosity function (LF) of AGN has been estimated in various ways. In the X-ray band, Chandra and XMM surveys (e.g., Barger et al. 2005; Hasinger, et al. 2005) have revealed that the LF of Hard X-ray selected AGN shows a strong luminosity-dependent evolution with a dramatic break towards low L(x) (at al z). This is seen for all types of AGN, but is stronger for the broad-line objects (e.g., Steffen et al. 2004). In sharp contrast, the local LF of optically-selected samples shows no such break and no differences between narrow and broad-line objects (Hao et al. 2005). If, as been suggested, hard X-ray and optical emission line can both be fair indicators of AGN activity, it is important to first understand how reliable these characteristics are if we hope to understand the apparent discrepancy in the LFs.

Angelini, L.↗

NASA NTRS2010

James Webb Space Telescope (JWST) and Star Formation

The 6.5-m aperture James Webb Space Telescope (JWST) will be a powerful tool for studying and advancing numerous areas of astrophysics. Its Fine Guidance Sensor, Near-Infrared Camera, Near-Infrared Spectrograph, and Mid-Infrared Instrument will be capable of making very sensitive, high angular resolution imaging and spectroscopic observations spanning 0.7 - 28 ?m wavelength. These capabilities are very well suited for probing the conditions of star formation in the distant and local Universe. Indeed, JWST has been designed to detect first light objects as well as to study the fine details of jets, disks, chemistry, envelopes, and the central cores of nearby protostars. We will be able to use its cameras, coronagraphs, and spectrographs (including multi-object and integral field capabilities) to study many aspects of star forming regions throughout the galaxy, the Local Group, and more distant regions. I will describe the basic JWST scientific capabilities and illustrate a few ways how they can be applied to star formation issues and conditions with a focus on Galactic regions.

Greene, Thomas P.↗

NASA NTRS1988

Attitude control of an object commonly held by multiple robot arms - A Lyapunov approach

Multiple robot arms moving a commonly held object can be viewed as complex actuators whose purpose is to provide net forces and moments to the object. These forces and moments can be used to control the orientation, or attitude, of the object via the Euler equation describing attitude evolution in response to applied moments at the mass center. In contrast to the common approach that feedback-linearizes the attitude dynamics to a double integrator form with respect to some three-parameter local representation of orientation, the authors control the object using a globally nonsingular representation. Using an energy-motivated Liapunov function, globally stable control of attitude is shown.

Kreutz, Kenneth↗