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Results for “immersion depth”

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.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Validation of NHB 8060.1C, Test 18 Arc Tracking, September 30, 1991

A test project was conducted to validate Test 18 of NASA Handbook (NHB) 8060.1C and, if necessary, identify and recommend improvements in the procedures or criteria of the test. The NHB 8060.1C, Test 18 test system was modified to produce better discrimination of test results. Changes, and their effects on test results, in the graphite immersion-depth, test timing sequence, and atmospheric conditions were investigated for the wire-insulation constructions tested. Based on the test results, the graphite immersion-depths (between 0.8 mm and 1.6 mm), the timing sequence, and the change in the test conditions from ambient to three environments common in manned spaceflight did not significantly affect test results. The criteria used in Test 18 of NHB 8060.1C was found to be appropriate for qualifying arc-tracking and arc-propagation characteristics of wire-insulation materials, Using the Test 18 criteria, Kapton and ETFE were considered inappropriate for use, while PTFE was considered appropriate. Recommendations from this test project for Test 18 of NHB 8060.1C include changing the experimental setup and configurational tests and performing qualification testing in air rather than in the three environments common in manned spaceflight.

Linley, Larry↗
NASA NTRS1974

Depth of immersion as a determinant of the natriuresis of water immersion

The current study was undertaken to further assess the contribution of an immersion-induced hydrostatic pressure gradient on the redistribution of blood volume. The rate of sodium excretion by seated subjects was significantly increased by water immersion up to the chest and neck compared to waist immersion and controls. These results are consistent with the hypothesis that whereas immersion to the level of the diaphragm merely cancels the intravascular hydrostatic pressure gradient by providing an identical external gradient, immersion above the diaphragm level results in increased water pressure which tends to favor a shift in blood volume from the lower extremities.

Epstein, M.↗
NASA NTRS1975

Error in temperature measurements due to conduction along the sensors

When a sensor is embedded in a solid body to measure its internal temperature, any conduction to or from its sensing element may cause the indicated temperature to be different from the true temperature. This paper describes an analysis of the error caused by conduction when there is an arbitrary temperature distribution in the body along the sensor. The sensor is modeled as a cylindrical fin and the appropriate conduction equation is solved. The solution gives a correction for the error which depends on such parameters as, depth of immersion, thermocouple wire and insulation properties, contact between the sensor and the body, and temperature distribution in the body. The latter may not be known, but the measured temperature distribution can be used as a first approximation. The corrected value can then be used to obtain a better estimate of the error. The results show good agreement with experimental observations.

Singh, B. S.↗
NASA NTRS1948

Theoretical motions of hydrofoil systems

Results are presented of an investigation that has been undertaken to develop theoretical methods of treating the motions of hydrofoil systems and to determine some of the important parameters. Variations of parameters include three distributions of area between the hydrofoils, two rates of change of downwash angle with angle of attack, three depths of immersion, two dihedral angles, two rates of change of lift with immersion, three longitudinal hydrofoil spacings, two radii of gyration in pitching, and various horizontal and vertical locations of the center of gravity. Graphs are presented to show locations of the center of gravity for stable motion, values of the stability roots, and motions following the sudden application of a vertical force or a pitching moment to the hydrofoil system for numerous sets of values of the parameters.

Imlay, Frederick H↗
NASA NTRS2023

Material around the Centaur (2060) Chiron from the 2018 November 28 UT Stellar Occultation

A stellar occultation of Gaia DR3 2646598228351156352 by the Centaur (2060) Chiron was observed from the South African Astronomical Observatory on 2018 November 28 UT. Here we present a positive detection of material surrounding Chiron from the 74-inch telescope for this event. Additionally, a global atmosphere is ruled out at the tens of microbars level for several possible atmospheric compositions. There are multiple 3σ drops in the 74-inch light curve: three during immersion and two during emersion. Occulting material is located between 242 and 270 km from the center of the nucleus in the sky plane. Assuming the ring-plane orientation proposed for Chiron from the 2011 occultation, the flux drops are located at 352, 344, and 316 km (immersion) and 357 and 364 km (emersion) from the center, with normal optical depths of 0.26, 0.36, and 0.22 (immersion) and 0.26 and 0.18 (emersion) and equivalent widths between 0.7 and 1.3 km. This detection is similar to the previously proposed two-ring system and is located within the error bars of that ring-pole plane; however, the normal optical depths are less than half of the previous values, and three features are detected on immersion. These results suggest that the properties of the surrounding material have evolved between the 2011, 2018, and 2022 observations.

Amanda A. Sickafoose↗
NASA NTRS1987

The 1 May 1982 stellar occultation by Uranus and the rings Observations from Mount Stromlo Observatory

The Klemola et al. (1981) object KME 15 has been observed by the Mount Stromlo 1.9-m telescope during its occultation by the Uranian rings on May 1, 1982. In addition to deriving accurate midtimes for rings 6, 5, 4, alpha, beta, eta, gamma, delta, and epsilon, on the basis of model fits to the immersion and emersion ring profiles, normal optical depths and equivalent widths are obtained for all save ring 6. The numerical inversion of immersion and emersion atmosphere occultation values has yielded vertical temperature profiles that exhibit mean temperatures in the vicinity of 130 K and a local maximum near the 8-microbar pressure level.

French, Richard G.↗
NASA NTRS1965

Photoelectric system continuously monitors liquid level

Immersion probe presents a depth-sensitive optical transmission path between a light source and a photoelectric cell to continuously monitor the level of a transparent liquid in a tank. This system operates automatically, without moving parts, and provides output signals to a remote recorder.

Source record↗
NASA NTRS1977

Occultation of Epsilon Geminorum by Mars. II - The structure and extinction of the Martian upper atmosphere

The occultation of Epsilon Geminorum by Mars on April 8, 1976, was observed at three wavelengths and 4-ms time resolution with the 91-cm telescope aboard NASA's G. P. Kuiper Airborne Observatory. Temperature, pressure, and number-density profiles of the Martian atmosphere were obtained for both the immersion and emersion events. Within the altitude range 50-80 km above the mean surface, the mean temperature is about 145 K, and the profiles exhibit wavelike structures with a peak-to-peak amplitude of 35 K and a vertical scale of about 20 km. The ratio of the refractivity of the atmosphere at 4500 A and 7500 A is consistent with the atmospheric composition measured by Viking 1. From the 'central flash' - a bright feature in the light curve midway between immersion and emersion - an optical depth at 4500 A of 3.3 + or - 1.7 per km atm (about 0.23 per equivalent Martian air mass) is found for the atmosphere about 25 km above the mean surface near the south polar region. This large value and its weak wavelength dependence rule out Rayleigh scattering as the principal cause of the observed extinction.

Elliot, J. L.↗
NASA NTRS1977

Occultation studies of planets and satellites: The occultation of epsilon Geminorum by Mars

The occultation of epsilon Geminorum by Mars on 1976 April 8 was observed at three wavelengths and 4 ms time resolution with the 91 cm telescope. Temperature, pressure, and number density profiles of the Martian atmosphere were obtained for both the immersion and emersion events. Within the altitude range of 50 to 80 km above the mean surface, the mean temperature is 145 K, and the profiles exhibit wavelike structures with a peak to peak amplitude of 35 K and a vertical scale of about 20 km. The ratio of the refractivity of the atmosphere at 4500 A and 7500 A, determined from the time shift of the light curves for these wavelengths, is consistent with the atmospheric composition measured by Viking 1, 15 weeks later. From the central flash - a bright feature in the light curve midway between immersion and emersion - an optical depth is found at 4500 A of 3.3 plus or minus 1.7 per km atm (about 0.23 per equivalent Martian air mass) for the atmosphere about 25 km above the mean surface, near the south polar region. This large value and its weak wavelength dependence rule out Rayleigh scattering as the principal cause of the observed extinction.

Elliot, J. L.↗
NASA NTRS1972

Survey of materials for hydrazine propulsion systems in multicycle extended life applications

An assessment is presented of materials compatibility data for hydrazine monopropellant propulsion systems applicable to the Space Shuttle vehicle missions. Materials were evaluated for application over a 10-yr/100-mission operational lifetime with minimum refurbishment. A general materials compatibility rating for a broad range of materials and several propellants based primarily on static liquid propellant immersion testing and an in-depth evaluation of hydrazine decomposition as a function of purity, temperature, material, surface conditions, etc., are presented. The most promising polymeric material candidates for propellant diaphragms and seals appear to have little effect on increasing hydrazine decomposition rates, but the materials themselves do undergo changes in physical properties which can affect their 10-yr performance in multicycle applications. The available data on these physical properties of elastomeric materials as affected by exposure to hydrazine or related environments are presented.

Coulbert, C. D.↗
NASA NTRSDate not supplied

Acquisition and Processing of Passive Thermography Fatigue Test Data

Passive thermography is a large area inspection technique and is commonly used during fatigue loading of composite structures. Passive thermography allows for real time tracking of damage. This provides an accurate assessment of the damage progression as a function of load cycles and determines when the loading is stopped for ultrasonic or X-ray CT evaluations for detail damage assessment through-the-thickness. In addition, if new areas of damage growth are detected, with passive thermography, then those areas are additionally inspected with ultrasound or X-ray CT. A custom developed passive thermography inspection system for fatigue loading is presented. Passive thermography of damage progression is compared to ultrasound inspections as a function of the fatigue cycles. Discussion is made on processing of the thermal data for periodic and non-periodic thermal responses.

Thermal nondestructive evaluation↗
NASA NTRS1978

Ocean thermal plant

A floating energy converter is described which uses large volumes of sea water to produce electrical power. In this plant, a fluid working medium is pumped to an evaporator where is is heated by a flow of warm surface sea water. The fluid in liquid form boils to a pressurized gas vapor which is routed to drive a turbine that, in turn, drives a generator for producing electricity. The gas vapor then enters a condenser immersed in cold sea water pumped from lower depths, condenses to its original liquid form, and then pumped to the evaporator to repeat the cycle. Modular components can be readily interchanged on the ocean thermal unit and inlet pipes for the sea water are provided with means for maintaining the pipes in alignment with the oncoming current. The modular construction allows for the testing of various components to provide a more rapid optimization of a standardized plant.

Owens, L. J.↗
NASA NTRS2009

Measurement of Trap Length for an Optical Trap

The trap length along the beam axis for an optical trap formed with an upright, oil-immersion microscope was measured. The goals for this effort were twofold. It was deemed useful to understand the depth to which an optical trap can reach for purposes of developing a tool to assist in the fabrication of miniature devices. Additionally, it was desired to know whether the measured trap length favored one or the other of two competing theories to model an optical trap. The approach was to trap a microsphere of known size and mass and raise it from its initial trap position. The microsphere was then dropped by blocking the laser beam for a pre-determined amount of time. Dropping the microsphere in a free-fall mode from various heights relative to the coverslip provides an estimate of how the trapping length changes with depth in water in a sample chamber on a microscope slide. While it was not possible to measure the trap length with sufficient precision to support any particular theory of optical trap formation, it was possible to find regions where the presence of physical boundaries influenced optical traps, and determine that the trap length, for the apparatus studied, is between 6 and 7 m. These results allow more precise control using optical micromanipulation to assemble miniature devices by providing information about the distance over which an optical trap is effective.

Wrbanek, Susan Y.↗
NASA NTRS2012

Testing of Candidate Rigid Heatshield Materials at LHMEL for the Entry, Descent, and Landing Technology Development Project

The material testing results described in this paper were part of a material development program of vendor-supplied, proposed heat shield materials. The goal of this program was to develop low density, rigid material systems with an appreciable weight savings over phenolic-impregnated carbon ablator (PICA) while improving material response performance. New technologies, such as PICA-like materials in honeycomb or materials with variable density through-the-thickness were tested. The material testing took place at the Wright-Patterson Air Force Base Laser Hardened Materials Laboratory (LHMEL) using a 10.6 micron CO2 laser operating with the test articles immersed in a nitrogen-gas environment at 1 atmosphere pressure. Test measurements included thermocouple readings of in-depth temperatures, pyrometer readings of surface temperatures, weight scale readings of mass loss, and sectioned-sample readings of char depth. Two laser exposures were applied. The first exposure was at an irradiance of 450 W/cm2 for 50 or 60 seconds to simulate an aerocapture maneuver. The second laser exposure was at an irradiance of 115 W/cm2 for 100 seconds to simulate a planetary entry. Results from Rounds 1 and 2 of these screening tests are summarized.

Sepka, Steven↗
NASA NTRS1998

Technology Development, Implementation, and Assessment: K-16 Pre-Service, In-Service, and Distance Learning Initiatives

This summer 22 kindergarten through 8th grade teachers attended a 3-week Teacher Enhancement Institute (TEI) at NASA Langley Research Center. TEI is funded by NASA Education Division and is a collaborative effort between NASA Langley's Office of Education and Christopher Newport University. Selected teacher teams were drawn from Langley's 5-state precollege service region, which includes Kentucky, North Carolina, South Carolina, Virginia, and West Virginia. The goal of TEI was for teachers to learn aeronautics and the broad application of science and technology through a problem-based learning (PBL) strategy. PBL is an instructional method using a real world problem, also known as an ill-structured problem, as the context for an in-depth investigation. Most real life problems are ill-structured, as are all the really important social, political and scientific problems. The teachers were immediately immersed in an ill-structured problem to design a communication strategy for the White House Commission on Aviation Safety and Security to educate and disseminate aviation information to the general public. Specifically, the communication strategy was to focus on aeronautics principles, technology and design associated with US general aviation revitalization and aviation safety programs. The presented problem addressed NASA's strategic outcome to widely communicate the content, relevancy and excitement of its missions and discoveries to the general population. Further, the PBL scenario addressed the technological challenges being taken up by NASA to revolutionize air travel and the way in which aircraft are designed, built, and operated. It also addressed getting people and freight safely and efficiently to any location in the world at a reasonable cost. With a "real" need-to-know problem facing them, the teachers set out to gather information and to better understand the problem using inquiry-based and scientific methods. The learning in this aeronautics scenario was driven by the direction taken by participants. With the support of the TEI faculty, the teachers quickly identified NASA Langley researchers that served as consultants to help solve the problem. To achieve their goal, the teacher teams developed lesson plans for elementary and middle school students, wrote a newspaper, published a brochure to educate the general public, constructed games for children of all ages, and produced a video. As a second problem, the TEI participants will design their own aeronautic lesson plan and immerse their 1997-98 school year students in the problem. The problem is for the students "to create a traveling hands-on, minds-on aeronautics museum exhibit created for children by children." As a culminating activity, the Virginia Air and Space Center in Hampton, VA, will set up a special display of the exhibits in the Summer 1998. The TEI faculty will visit each TEI teacher's classroom during the academic school year to observe the implementation of the unit. In addition to the classroom observations, electronic follow-up sessions will be conducted during the school year to support the teachers' efforts in developing their PBL units to integrate technology in math and science instruction. These sessions eill be conducted using the Internet. Teachers will be connected through a chat-line to share ideas, ask questions, and generate solutions.

Petersen, Richard↗
NASA NTRS1987

The occultation of KME 17 by Uranus and its rings

K-filter/InSb observations of the March 25, 1983 occultation of KME 17 by Uranus and its rings yielded nonchopping-mode recordings of the immersion of the nine main rings and the emersion of rings 5, 4, alpha, and beta; a diffracted square-well model has been fitted to these data in order to derive the midtime, width, and equivalent depth for each profile, in view of a profile model encompassing the diameter of the occulted star as a free parameter. Assuming a fully darkened disk, the angular diameter of KME 17 is 0.096 + or - 0.005 milliarcsec. Attention is also given to JHKL-band photometry for both KME 17 and other Uranian-ring-occulted stars.

Elliot, J. L.↗
NASA NTRS1999

Visualizing Mars Using Virtual Reality: A State of the Art Mapping Technique Used on Mars Pathfinder

We describe an interactive terrain visualization system which rapidly generates and interactively displays photorealistic three-dimensional (3-D) models produced from stereo images. This product, first demonstrated in Mars Pathfinder, is interactive, 3-D, and can be viewed in an immersive display which qualifies it for the name Virtual Reality (VR). The use of this technology on Mars Pathfinder was the first use of VR for geologic analysis. A primary benefit of using VR to display geologic information is that it provides an improved perception of depth and spatial layout of the remote site. The VR aspect of the display allows an operator to move freely in the environment, unconstrained by the physical limitations of the perspective from which the data were acquired. Virtual Reality offers a way to archive and retrieve information in a way that is intuitively obvious. Combining VR models with stereo display systems can give the user a sense of presence at the remote location. The capability, to interactively perform measurements from within the VR model offers unprecedented ease in performing operations that are normally time consuming and difficult using other techniques. Thus, Virtual Reality can be a powerful a cartographic tool. Additional information is contained in the original extended abstract.

Stoker, C.↗