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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Composition and freezing of aqueous H2SO4/HNO3 solutions under polar stratospheric conditions

The results of laboratory investigations of the freezing behavior of aqueous acid solutions indicate that in the stratosphere H2SO/H2O aerosol droplets would not freeze at temperatures above the ice frost point in the absence of HNO3; however, in the presence of typical levels of HNO3 liquid sulfuric acid aerosols take up significant amounts of HNO3 and H2O vapors and freeze much more readily. This is a consequence of the very rapid change in composition of the liquid droplets as the temperature drops to within two to three degrees of the equilibrium temperature at which HNO3 and H2O vapors would co-condense to form a liquid solution. In the high latitude stratosphere this HNO3/H2O 'dew point' is typically around 192-194 K at 100 mbar.

Beyer, K. D.↗
NASA NTRS1973

Space vehicle with artificial gravity and earth-like environment

A space vehicle adapted to provide an artificial gravity and earthlike atmospheric environment for occupants is disclosed. The vehicle comprises a cylindrically shaped, hollow pressure-tight body, one end of which is tapered from the largest diameter of the body, the other end is flat and transparent to sunlight. The vehicle is provided with thrust means which rotates the body about its longitudinal axis, generating an artificial gravity effect upon the interior walls of the body due to centrifugal forces. The walls of the tapered end of the body are maintained at a temperature below the dew point of water vapor in the body and lower than the temperature near the transparent end of the body. The controlled environment and sunlight permits an earth like environment to be maintained wherein the CO2/O2 is balanced, and food for the travelers is supplied through a natural system of plant life grown on spacecraft walls where soil is located.

Gray, V. H.↗
NASA NTRS1976

Aircraft measurements and analysis of severe storms: 1975 field experiment

Three aircraft and instrumentation systems were acquired in support of the severe storm surveillance program. The data results indicate that the original concept of a highly mobile research aircraft capability for obtaining detailed measurements of wind, temperature, dew point, etc., near and within specifically designated severe storms is entirely feasible and has been demonstrated for the first time by this program. This program is unique in that it is designed to be highly mobile in order to move to and/or with the developing storm systems to obtain the necessary measurements. Previous programs have all been fixed to a particular location and therefore have had to wait for the storms to come within their network. The present research is designed around a highly mobile aircraft measurements group in order to maximize the storm cases during the field measurements program.

Sinclair, P. C.↗
NASA NTRS1977

Theoretical and experimental studies of the deposition of Na2So4 from seeded combustion gases

Flames in a Mach 0.3 atmospheric pressure laboratory burner rig were doped with sea salt, NaS04, and NaCl, respectively, in an effort to validate theoretical dew point predictions made by a local thermochemical equilibrium (LTCE) method of predicting condensation temperatures of sodium sulfate in flame environments. Deposits were collected on cylindrical platinum targets placed in the combustion products, and the deposition was studied as a function of collector temperature. Experimental deposition onset temperatures checked within experimental error with LTCE-predicted temperatures. A multicomponent mass transfer equation was developed to predict the rate of deposition of Na2SO4(c) via vapor transport at temperatures below the deposition onset temperature. Agreement between maximum deposition rates predicted by this chemically frozen boundary layer (CFBL) theory and those obtained in the seeded laboratory burner experiments is good.

Kohl, F. J.↗
NASA NTRS1977

Variation of forearm, hand, and finger blood flow indices with ambient temperature

Forearm, hand, and finger blood flow (impedance) changes are measured by impedance rheography on seven healthy male subjects aged 20-35 yr during exposure to ambient temperatures ranging from 10 to 46 C. All observations are made in an environmental chamber at a dew point temperature of 13 + or - 0.25 C. It is shown that impedance rheography is suitable for quantifying peripheral circulatory responses to thermal stress. The measured blood flow indices are found to be consistent with previously reported values for the forearm, hand, and fingers obtained using air or water displacement plethysmography. In particular, the more distal body segments exhibit relatively larger vasomotor responses to changes in ambient temperature than do the more proximal body segments.

Montgomery, L. D.↗
NASA NTRS1978

An Induced Environment Contamination Monitor for the Space Shuttle

The Induced Environment Contamination Monitor (IECM), a set of ten instruments integrated into a self-contained unit and scheduled to fly on shuttle Orbital Flight Tests 1 through 6 and on Spacelabs 1 and 2, is described. The IECM is designed to measure the actual environment to determine whether the strict controls placed on the shuttle system have solved the contamination problem. Measurements are taken during prelaunch, ascent, on-orbit, descent, and postlanding. The on-orbit measurements are molecular return flux, background spectral intensity, molecular deposition, and optical surface effects. During the other mission phases dew point, humidity, aerosol content, and trace gas are measured as well as optical surface effects and molecular deposition. The IECM systems and thermal design are discussed. Preflight and ground operations are presented together with associated ground support equipment. Flight operations and data reduction plans are given.

Miller, E. R.↗
NASA NTRS1977

Variational analysis of temperature and moisture advection in a severe storm environment

Horizontal wind components, potential temperature, and mixing ratio fields associated with a severe storm environment in the south central United States were objectively analyzed from synoptic upper air observations with a nonhomogeneous anisotropic weighting function. The particular case study discussed here is the tornado producting squall line which moved through eastern Oklahoma 26 May 1973. The synoptic situation which preceded squall line development was cyclogenesis and frontogenesis in the lee-of-mountain trough, which produced a well-defined surface dry line (or dew point front) and a pronounced mid-level dry air intrusion. It is shown that the intrusion was also characterized by warm air, with a lapse rate approaching the dry adiabatic.

Mcfarland, M. J.↗
NASA NTRS1979

Design, fabrication and delivery of a prototype saturator for ACPL

The design configuration and performance characteristics of a saturator developed to provide ground-based simulation for some of the experiments for ACPL-1 first flights of Spacelab are described, some difficulties encountered with the apparatus are discussed, and recommendations concerning testing of this type of instrument are presented. The saturators provide a means of accurately fixing the water vapor mixing ratio of an aerosol sample. Dew point temperatures from almost freezing to ambient room temperatures can be attained with high precision. The instruments can accommodate aerosol flow rates approaching 1000 cc/s. Provisions were made to inject aerosols upstream of these saturators, although downstream injection can be accomplished as well. A device of this type will be used in the ACPL-1 to condition various aerosols delivered concurrently to a CFD, expansion chamber, and static diffusion chamber used in zero gravity cloud-forming experiments. The saturator was designed to meet the requirements projected for the flight instrument.

Keyser, G.↗
NASA NTRS1979

Operating manual for the RRL 8 channel data logger

A data collection device which takes measurements from external sensors at user specified time intervals is described. Three sensor ports are dedicated to temperature, air pressure, and dew point. Five general purpose sensor ports are provided. The user specifies when the measurements are recorded as well as when the information is read or stored in a minicomputer or a paper tape.

Paluch, E. J.↗
NASA NTRS1978

Experimental studies of the formation/deposition of sodium sulfate in/from combustion gases

Interference in a reflected beam of monochromatic light from a linearly polarized helium-neon laser was used to determine the dew point and deposition rate of B2O3 on a heated platinum target. Preliminary results at different BCl3 seed levels, except for one flow velocity and equivalence ratio (.813) are presented and discussed. Alkali chloride reactions with atomic oxygen were also investigated. Readily detectable Na*(g) and K*(g) - atoms were observed in emission at 589 nm, 766nm, 796nm, respectively.

Rosner, D. E.↗
NASA NTRS1979

Numerical simulation of VTPR temperature retrievals in a severe storm environment

Environmental conditions prior to convective development on the Great Plains of the U.S. on one case study day were investigated using the high-resolution infrared radiation sounder (HIRS) on Nimbus 6. A dual-retrieval scheme was developed to retrieve both lower tropospheric moisture and temperature parameters from the HIRS radiances. Total precipitable water, surface dew point temperatures, and stability indices were analyzed at a resolution of up to 30 Km on this day. Correlations with interpolated NES rawinsonde values were high and intrinsic noise levels were low. The true quality of the mesoscale analyses, however, is only seen by examining the small scale features at a scale of approximately 100 Km. Perturbations on the dry line feature for this day were seen in the satellite data, although the dry line position was just as easily picked up by surface observations. Convective development 2 1/2 hours later did seem to correlate well with the local maxima of moisture and instability seen in the satellite analyses.

Vonderhaar, T. H.↗
NASA NTRS1979

Development of a Model and Computer Code to Describe Solar Grade Silicon Production Processes

The program aims at developing mathematical models and computer codes based on these models, which allow prediction of the product distribution in chemical reactors for converting gaseous silicon compounds to condensed-phase silicon. The major interest is in collecting silicon as a liquid on the reactor walls and other collection surfaces. Two reactor systems are of major interest, a SiCl4/Na reactor in which Si(l) is collected on the flow tube reactor walls and a reactor in which Si(l) droplets formed by the SiCl4/Na reaction are collected by a jet impingement method. During this quarter the following tasks were accomplished: (1) particle deposition routines were added to the boundary layer code; and (2) Si droplet sizes in SiCl4/Na reactors at temperatures below the dew point of Si are being calculated.

Srivastava, R.↗
NASA NTRS1979

Surface observations for the evaluation of geophysical measurements from Seasat

The surface observations used for direct comparison with Seasat-derived values at fixed locations and as input to analyzed fields of pressure, wind, air and sea temperatures, and surface dew point are discussed. These included measurements made by research vessels participating in the Gulf of Alaska Seasat Experiment (GOASEX) and NOAA research platforms in addition to aircraft observations and reports from the World Weather Watch. The application of these observations in describing the synoptic-scale winds over the ocean is discussed, and the sensitivity of the verification statistics to the type of data (observations from buoys, weather ships, and transient vessels with or without anemometers) is considered. Results of a preliminary comparison of wind fields derived from Seasat-A scatterometer observation with winds specified by several types of platforms are presented.

Wilkerson, J. C.↗
NASA NTRS1980

Performance characterization of a Bosch CO sub 2 reduction subsystem

The performance of Bosch hardware at the subsystem level (up to five-person capacity) in terms of five operating parameters was investigated. The five parameters were: (1) reactor temperature, (2) recycle loop mass flow rate, (3) recycle loop gas composition (percent hydrogen), (4) recycle loop dew point and (5) catalyst density. Experiments were designed and conducted in which the five operating parameters were varied and Bosch performance recorded. A total of 12 carbon collection cartridges provided over approximately 250 hours of operating time. Generally, one cartridge was used for each parameter that was varied. The Bosch hardware was found to perform reliably and reproducibly. No startup, reaction initiation or carbon containment problems were observed. Optimum performance points/ranges were identified for the five parameters investigated. The performance curves agreed with theoretical projections.

Heppner, D. B.↗
NASA NTRS1980

The 1979 Southeastern Virginia Urban Plume Study (SEV-UPS): Surface and airborne studies

The operation of two surface monitoring stations (one in downtown Norfolk, Virginia, one south of the city near the Great Dismal Swamp) and the collection of 40 hours of airborne measurements is described. Surface site measurements of ozone, oxides of nitrogen, sulfur dioxide, temperature, dew point, b sub seat, and condensation nuclei were made. Instrument calibrations, quality assurance audits, and preliminary data analysis in support of the Urban Plume Study were also made. The air pollution problems that were addressed are discussed. Data handling procedures followed for the surface stations are presented. The operation of the aircraft sampling platform is described. Aircraft sampling procedures are discussed. A preliminary descriptive analysis of the aircraft data is given along with data or plots for surface sites, airborne studies, hydrocarbon species, and instrument performance audits. Several of the aircraft flights clearly show the presence of an urban ozone plume downwind of Norfolk in the direction of the mean wind flow.

White, J. H.↗
NASA NTRS1980

A preliminary assessment of the accuracy of selected meteorological parameters determined from Nimbus 6 satellite profile data

Published rms errors in rawinsonde data and discrepancies between satellite and rawinsonde profile data for temperature, dewpoint temperature, mixing ratio, and wind speed. Satellite rms errors were found to be 2 to 3 times as large as those for rawinsonde data. Gradients of the preceding parameters were computed for both rawinsonde and satellite data and compared with means and near extreme values computed from the AVE 2 and AVE 4 experiments. In all cases, it was found that satellite data can be used to determine with relatively good accuracy the near extreme gradients but not those whose value does not exceed the average. Synoptic charts were prepared to show that patterns of temperature could be determined with relatively good accuracy, while those of dew point were not as good as those for temperature. Winds represented by cloud motion vectors (satellite winds) were compared with rawinsonde winds, and it was found that large gaps exist in satellite values for a given pressure level and that errors in the satellite determined concluded that satellite profile data are very useful in synoptic analysis, particularly in data sparse regions as well as regions where near extreme gradients exist in the measured parameters.

Scoggins, J. R.↗
NASA NTRS1980

The program of the Techniques Development Laboratory in aviation weather forecasting

Some operational and experimental products developed for aviation weather forecasting are briefly described. Experimental products include surface dew point, obstructions to vision, boundary layer model, computer-worded terminal forecasts, terminal alerting procedure, generalized equivalent Markov, and radar forecasts (0-2 hours).

Klein, W. H.↗