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At least 1,207 records · Page 67

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NASA NTRS1987

Physiologic adaptation of man in space; Proceedings of the Seventh International Man in Space Symposium, Houston, TX, Feb. 10-13, 1986

Topics discussed in this volume include space motion sickness, cardiovascular adaptation, fluid shifts, extravehicular activity, general physiology, perception, vestibular response modifications, vestibular physiology, and pharmacology. Papers are presented on the clinical characterization and etiology of space motion sickness, ultrasound techniques in space medicine, fluid shifts in weightlessness, Space Shuttle inflight and postflight fluid shifts measured by leg volume changes, and the probability of oxygen toxicity in an 8-psi space suit. Consideration is also given to the metabolic and hormonal status of crewmembers in short-term space flights, adaptive changes in perception of body orientation and mental image rotation in microgravity, the effects of a visual-vestibular stimulus on the vestibulo-ocular reflex, rotation tests in the weightless phase of parabolic flight, and the mechanisms of antimotion sickness drugs.

Holland, Albert W.↗

NASA NTRS1988

Radiometric performance of AVIRIS: Assessment for an arid region geologic target

Data from several AVIRIS flight lines were examined to assess instrument stability and response. Both scene and in-flight calibration data were analyzed statistically. The data clearly indicates that, although the instrument output was noisy and unstable at the time of the data acquisition, valuable spectral signatures can still be extracted and analyzed. Some first order calibration corrections can be performed by forcing internal consistency within the data. AVIRIS data are delivered in band-interleaved-by-line format, but high efficiency routines were developed which access the data as either image or spectral planes and enable effective statistical and visual examination of both AVIRIS scenes and ancillary files. Two methods were used to extract spectral information from segment 4 of the Kelso Dunes flight. Both successfully identified at least three distinct spectral signatures, but neither has positively identified a specific material.

Kieffer, Hugh H.↗

NASA NTRS1990

Borescope Aids Welding In Confined Spaces

Welding torch holds video borescope to give operator view of workpiece in enclosed space. Operator sees clear, magnified image on video monitor and manipulates torch accordingly, despite visual obstruction presented by enclosure. Tinted shield tilted up while torch being positioned, then down to block excess light during welding. Reduces welding time by 50 percent, and increases quality of weld substantially.

Carrasco, Eddie↗

NASA NTRS1990

The intensity dependent spread model and color constancy

Odetics is investigating the use of the intensity dependent spread (IDS) model for determining color constancy. Object segmentation is performed effortlessly by the human visual systems, but creating computer vision that takes an image as input and performs object identification on the basis of color has some difficulties. The unknown aspects of the light illuminating a scene in space or anywhere can seriously interfere with the use of color for object identification. The color of an image depends not only on the physical characteristics of the object, but also on the wavelength composition of the incident illumination. IDS processing provides the extraction of edges and of reflectance changes across edges, independent of variations in scene illumination. IDS depends solely on the ratio of the reflectances on the two sides of the edge. Researchers are in the process of using IDS to recover the reflectance image.

Kurrasch, Ellie↗

NASA NTRS1990

An approach for relating the results of quantitative nondestructive evaluation to intrinsic properties of high-performance materials

One of the most difficult problems the manufacturing community has faced during recent years has been to accurately assess the physical state of anisotropic high-performance materials by nondestructive means. In order to advance the design of ultrasonic nondestructive testing systems, a more fundamental understanding of how ultrasonic waves travel and interact within the anisotropic material is needed. The relationship between the ultrasonic and engineering parameters needs to be explored to understand their mutual dependence. One common denominator is provided by the elastic constants. The preparation of specific graphite/epoxy samples to be used in the experimental investigation of the anisotropic properties (through the measurement of the elastic stiffness constants) is discussed. Accurate measurements of these constants will depend upon knowledge of refraction effects as well as the direction of group velocity propagation. The continuing effort for the development of improved visualization techniques for physical parameters is discussed. Group velocity images are presented and discussed. In order to fully understand the relationship between the ultrasonic and the common engineering parameters, the physical interpretation of the linear elastic coefficients (the quantities that relate applied stresses to resulting strains) are discussed. This discussion builds a more intuitional understanding of how the ultrasonic parameters are related to the traditional engineering parameters.

Miller, James G.↗

NASA NTRS1988

Surface flow visualization in the cryogenic wind tunnel

The prospects are reviewed of a range of possible surface flow visualization methods for application to model testing in the large cryogenic wind tunnel. Desirable features are outlined, including the flow details which should be revealed by the various methods. The risks of model and tunnel contamination are discussed, also the coverage of the model surface to be expected, the advance planning and complexity of model design and tunnel equipment required by the visualization method, and the prospects of generating multiple flow images during one tunnel run. The techniques range from the untried to several on which already there is some experience in the cryogenic environment. Directions for further development are suggested.

Goodyer, M. J.↗

NASA NTRS1993

The Effects of Gravity on Wrinkled Laminar Flames

The effects of gravity are significant to the dynamics of idealized unconfined open premixed flames. Moderate to low turbulence Reynolds number flames, i.e., wrinkled laminar flames, of various unconfined geometries have been used extensively for investigating fundamental processes of turbulent flame propagation and to validate theoretical models. Without the wall constraints, the flames are free to expand and interact with surrounding ambient air. The flow field in which the flame exists is determined by a coupling of burner geometry, flame orientation and the gravity field. These complex interactions raise serious questions regarding the validity of comparing the experimental data of open flames with current theoretical and numerical models that do not include the effects of gravity nor effects of the larger aerodynamic flowfield. Therefore, studies of wrinkled laminar flame in microgravity are needed for a better understanding of the role of gravity on flame characteristics such as the orientation, mean aerodynamics stretch, flame wrinkle size and burning rate. Our approach to characterize and quantify turbulent flame structures under microgravity is to exploit qualitative and quantitative flow visualization techniques coupled with video recording and computer controlled image analysis technologies. The experiments will be carried out in the 2.2 second drop tower at the NASA Lewis Research Center. The longest time scales of typical wrinkled laminar flames in the geometries considered here are in the order of 10 msec. Hence, the duration of the drop is sufficient to obtain the amount of statistical data necessary for characterize turbulent flame structures.

Kostiuk, Larry W.↗

NASA NTRS1992

EVA Glove Research Team

The goal of the basic research portion of the extravehicular activity (EVA) glove research program is to gain a greater understanding of the kinematics of the hand, the characteristics of the pressurized EVA glove, and the interaction of the two. Examination of the literature showed that there existed no acceptable, non-invasive method of obtaining accurate biomechanical data on the hand. For this reason a project was initiated to develop magnetic resonance imaging as a tool for biomechanical data acquisition and visualization. Literature reviews also revealed a lack of practical modeling methods for fabric structures, so a basic science research program was also initiated in this area.

Strauss, Alvin M.↗

NASA NTRS1992

Mass movements on Venus - Preliminary results from Magellan cycle 1 observations

A preliminary assessment of mass movements and their geomorphic characteristics as determined from visual inspection of Magellan cycle 1 synthetic aperture radar images is described. The primary data set was a catalog of over 200 ten-inch square photographic prints of full-resolution mosaic image data records. Venus exhibits unambiguous evidence of mass movements at a variety of scales. Mass movements appear mostly in the form of block and rock movements; there is little evidence of regolith and sediment movements. Unique Venusian conditions may play a role in the creation of some mass movement features. Dark (smooth) surfaces surrounding many rockslide avalanches are probably fine materials emplaced as part of the mass movement process, as airfall, surface-hugging density flows, or coarse-depleted debris flows. The size and efficiency of emplacement of landslide deposits on Venus are comparable to those seen on Mars, which in turn generally resemble terrestrial occurrences.

Malin, Michael C.↗

NASA NTRS1998

Measurements of Heat Transfer, Flow, and Pressures in a Simulated Turbine Blade Internal Cooling Passage

An experimental study was made to obtain quantitative information on heat transfer, flow, and pressure distribution in a branched duct test section that had several significant features of an internal cooling passage of a turbine blade. The objective of this study was to generate a set of experimental data that could be used for validation of computer codes that would be used to model internal cooling. Surface heat transfer coefficients and entrance flow conditions were measured at nominal entrance Reynolds numbers of 45,000, 335,000, and 726,000. Heat transfer data were obtained by using a steady-state technique in which an Inconel heater sheet is attached to the surface and coated with liquid crystals. Visual and quantitative flow-field data from particle image velocimetry measurements for a plane at midchannel height for a Reynolds number of 45,000 were also obtained. The flow was seeded with polystyrene particles and illuminated by a laser light sheet. Pressure distribution measurements were made both on the surface with discrete holes and in the flow field with a total pressure probe. The flow-field measurements yielded flow-field velocities at selected locations. A relatively new method, pressure sensitive paint, was also used to measure surface pressure distribution. The pressure paint data obtained at Reynolds numbers of 335,000 and 726,000 compared well with the more standard method of measuring pressures by using discrete holes.

Russell, Louis M.↗

NASA NTRS1994

Visibility of DCT Basis Functions: Effects of Contrast Masking

Current strategies for compressing images neglect to accommodate certain aspects of the human visual system. One such neglected aspect is contrast masking. Here we provide measurements of contrast masking within the framework of the discrete cosine transform (DCT). We describe how to optimize DCT-based compression with respect to contrast masking.

Soloman, Joshua A.↗

NASA NTRS2002

Solid Hydrogen Experiments for Atomic Propellants: Image Analyses

This paper presents the results of detailed analyses of the images from experiments that were conducted on the formation of solid hydrogen particles in liquid helium. Solid particles of hydrogen were frozen in liquid helium, and observed with a video camera. The solid hydrogen particle sizes, their agglomerates, and the total mass of hydrogen particles were estimated. Particle sizes of 1.9 to 8 mm (0.075 to 0.315 in.) were measured. The particle agglomerate sizes and areas were measured, and the total mass of solid hydrogen was computed. A total mass of from 0.22 to 7.9 grams of hydrogen was frozen. Compaction and expansion of the agglomerate implied that the particles remain independent particles, and can be separated and controlled. These experiment image analyses are one of the first steps toward visually characterizing these particles, and allow designers to understand what issues must be addressed in atomic propellant feed system designs for future aerospace vehicles.

Palaszewski, Bryan↗

NASA NTRS2002

Solid Hydrogen Experiments for Atomic Propellants: Particle Formation Energy and Imaging Analyses

This paper presents particle formation energy balances and detailed analyses of the images from experiments that were conducted on the formation of solid hydrogen particles in liquid helium during the Phase II testing in 2001. Solid particles of hydrogen were frozen in liquid helium and observed with a video camera. The solid hydrogen particle sizes and the total mass of hydrogen particles were estimated. The particle formation efficiency is also estimated. Particle sizes from the Phase I testing in 1999 and the Phase II testing in 2001 were similar. Though the 2001 testing created similar particles sizes, many new particle formation phenomena were observed. These experiment image analyses are one of the first steps toward visually characterizing these particles and it allows designers to understand what issues must be addressed in atomic propellant feed system designs for future aerospace vehicles.

Palaszewski, Bryan↗

NASA NTRS2004

DSP Implementation of the Retinex Image Enhancement Algorithm

The Retinex is a general-purpose image enhancement algorithm that is used to produce good visual representations of scenes. It performs a non-linear spatial/spectral transform that synthesizes strong local contrast enhancement and color constancy. A real-time, video frame rate implementation of the Retinex is required to meet the needs of various potential users. Retinex processing contains a relatively large number of complex computations, thus to achieve real-time performance using current technologies requires specialized hardware and software. In this paper we discuss the design and development of a digital signal processor (DSP) implementation of the Retinex. The target processor is a Texas Instruments TMS320C6711 floating point DSP. NTSC video is captured using a dedicated frame-grabber card, Retinex processed, and displayed on a standard monitor. We discuss the optimizations used to achieve real-time performance of the Retinex and also describe our future plans on using alternative architectures.

Hines, Glenn↗

NASA NTRS1998

Role of the flocculus of the cerebellum in motor learning of the vestibulo-ocular reflex

Structure-function studies at the systems level are an effective method for understanding the relationship of the central nervous system to behavior. Motor learning or adaptation of the vestibulo-ocular reflex is a clear example wherein this approach has been productive. During a vestibulo-ocular reflex the brain converts a head velocity signal, transduced through the vestibular semicircular canals, into an eye movement command delivered to the extraocular muscles. If the viewed target remains on the fovea of the retina, the reflex is compensatory, and its gain, eye velocity/head velocity, is one. When the image of the viewed object slips across the retina, visual acuity decreases, and the gain of the reflex, which is no longer one, is plastically adapted or adjusted until retinal stability is restored. The anatomic substrate for this plasticity thus involves brain structures in which visual-vestibular interaction can potentially occur, as well as vestibular and visual sensory and oculomotor motor structures. Further, it has been known for many years that removal of the flocculus of the cerebellum permanently precludes further vestibulo-ocular reflex adaptation, demonstrating the involvement of the cerebellum in this behavior. Maekawa and Simpson (J Neurophysiol 1973;36: 649-66) discovered that one visual input to the flocculus involved the accessory optic system and the inferior olive. Ensuing work has demonstrated that the visual signals used to adapt the vestibulo-ocular reflex are transmitted by this accessory optic system to the flocculus and subsequently to brain stem structures involved in vestibulo-ocular reflex plasticity. Presently the inclusive list of anatomic sites involved in vestibulo-ocular reflex circuitry and its adaptive plasticity is small. Our laboratory continues to believe that this behavior should be caused by interactions within this small class of neurons. By studying each class of identified neuron and its interactions with others within the list, we hope to ultimately understand the mechanisms used by the brain in the expression of this behavior.

Non-NASA Center↗

NASA NTRS2005

Solid Hydrogen Experiments for Atomic Propellants: Particle Formation, Imaging, Observations, and Analyses

This report presents particle formation observations and detailed analyses of the images from experiments that were conducted on the formation of solid hydrogen particles in liquid helium. Hydrogen was frozen into particles in liquid helium, and observed with a video camera. The solid hydrogen particle sizes and the total mass of hydrogen particles were estimated. These newly analyzed data are from the test series held on February 28, 2001. Particle sizes from previous testing in 1999 and the testing in 2001 were similar. Though the 2001 testing created similar particles sizes, many new particle formation phenomena were observed: microparticles and delayed particle formation. These experiment image analyses are some of the first steps toward visually characterizing these particles, and they allow designers to understand what issues must be addressed in atomic propellant feed system designs for future aerospace vehicles.

Palaszewski, Bryan↗

NASA NTRS2004

DSP Implementation of the Multiscale Retinex Image Enhancement Algorithm

The Retinex is a general-purpose image enhancement algorithm that is used to produce good visual representations of scenes. It performs a non-linear spatial/ spectral transform that synthesizes strong local contrast enhancement and color constancy. A real-time, video frame rate implementation of the Retinex is required to meet the needs of various potential users. Retinex processing contains a relatively large number of complex computations, thus to achieve real-time performance using current technologies requires specialized hardware and software. In this paper we discuss the design and development of a digital signal processor (DSP) implementation of the Retinex. The target processor is a Texas Instruments TMS320C6711 floating point DSP. NTSC video is captured using a dedicated frame grabber card, Retinex processed, and displayed on a standard monitor. We discuss the optimizations used to achieve real-time performance of the Retinex and also describe our future plans on using alternative architectures.

Hines, Glenn D.↗

NASA NTRS2006

System and method for improving ultrasound image acquisition and replication for repeatable measurements of vascular structures

High resolution B-mode ultrasound images of the common carotid artery are obtained with an ultrasound transducer using a standardized methodology. Subjects are supine with the head counter-rotated 45 degrees using a head pillow. The jugular vein and carotid artery are located and positioned in a vertical stacked orientation. The transducer is rotated 90 degrees around the centerline of the transverse image of the stacked structure to obtain a longitudinal image while maintaining the vessels in a stacked position. A computerized methodology assists operators to accurately replicate images obtained over several spaced-apart examinations. The methodology utilizes a split-screen display in which the arterial ultrasound image from an earlier examination is displayed on one side of the screen while a real-time live ultrasound image from a current examination is displayed next to the earlier image on the opposite side of the screen. By viewing both images, whether simultaneously or alternately, while manually adjusting the ultrasound transducer, an operator is able to bring into view the real-time image that best matches a selected image from the earlier ultrasound examination. Utilizing this methodology, measurement of vascular dimensions such as carotid arterial IMT and diameter, the coefficient of variation is substantially reduced to values approximating from about 1.0% to about 1.25%. All images contain anatomical landmarks for reproducing probe angulation, including visualization of the carotid bulb, stacking of the jugular vein above the carotid artery, and initial instrumentation settings, used at a baseline measurement are maintained during all follow-up examinations.

Selzer, Robert H.↗