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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

GYC: A program to compute the turbulent boundary layer on a rotating cone

A computer program, GYC, which is capable of computing the properties of a compressible turbulent boundary layer on a rotating axisymmetric cone-cylinder body, according to the principles of invariant modeling was studied. The program is extended to include the calculation of the turbulence scale by a differential equation. GYC is in operation on the CDC-7600 computer and has undergone several corrections and improvements as a result of the experience gained. The theoretical basis for the program and the method of implementation, as well as information on its operation are given.

Sullivan, R. D.↗
NASA NTRS1986

A search for the prewetting line

This paper describes efforts to locate the prewetting line in a binary liquid system (isopropanol-perfluoromethylcyclohexane) at the vapor-liquid interface. Tight upper bounds were placed on the temperature separation (0.2 K) between the prewetting line and the line of bulk liquid phase separation. The prewetting line in systems at equilibrium was not detected. Experimental signatures indicative of the prewetting line occurred only in nonequilibrium situations. Several theories predict that the adsorption of one of the components (the fluorocarbon, in this case) at the liquid-vapor interface should increase abruptly, at a temperature sightly above the temperature at which the mixture separates into two liquid phases. A regular solution calculation indicates that this prewetting line should have been easily detectable with the instruments used in this experiment. Significant features of the experiment are: (1) low-gradient thermostatting, (2) in situ stirring, (3) precision ellipsometry from the vapor-liquid interface, (4) high resolution differential index of refraction measurements using a novel cell design, and (5) computer control.

Schmidt, J. W.↗
NASA NTRS1988

The meteorological measurement system on the NASA ER-2 aircraft

A Meteorological Measurement System (MMS) was designed for the high-altitude ER-2 aircraft (NASA 706). Through dedicated instrumentation installed on the aircraft and repeated calibrations, the MMS provides accurate in situ measurements of free-stream pressure, temperature, and the wind vector. The MMS has participated in two major high-altitude scientific expeditions, the Stratosphere-Troposphere Exchange Project (STEP) based in northern Australia and the Airborne Antarctic Ozone Experiment (AAOE) based in southern Chile. Key MMS subsystems are described. The MMS consists of a dedicated inertial navigation system (INS), a randome differential pressure system, a data acquisition system, and air data instrumentation. The MMS incorporates a high-resolution INS (Litton LIN-72RH model), which is specially configured and is updated at 25 Hz. The differential pressure system, consisting of two sets of pressure ports and transducers, is installed in the ER-2 radome to provide sensitive measurements of the airflow angles (angle of attack and angle of sideslip). The data acquisition system was designed to meet aircraft requirements of compactness and light weight (2 cu ft 50 lb) and for MMS requirements to sample, control, process, and store 45 parameters (some redundant) at a sampling rate up to 10 Hz. The MMS data are stored both in a tape recorder (20 MB) and a hermatically-sealed winchester hard disc (10 MB). Special and redundant instrumentation for temperature and pressure measurements were also installed on the aircraft.

Scott, Stan G.↗
NASA NTRS1990

SHOOT flowmeter and pressure transducers

A venturi flowmeter has been designed and constructed for the Superfluid Helium On-Orbit Transfer (SHOOT) experiment. The calibration results obtained from the SHOOT venturi demonstrate the ability of the flowmeter to meet the requirements of the SHOOT experiment. Flow rates as low as 20 cu dm/h and as high as 800 cu dm/h have been measured. Performances of the SHOOT differential and absolute pressure transducers, which have undergone calibration and vibration tests, are also included. Throughout the tests, the responses of the transducers remained linear and repeatable to within + or - 1 percent of the full scales of the transducers.

Kashani, A.↗
NASA NTRS1991

Raman shifting of KrF laser radiation for tropospheric ozone measurements

The differential absorption lidar (DIAL) measurement of tropospheric ozone requires use of high average power UV lasers operating at two appropriate DIAL wavelengths. Laboratory experiments have demonstrated that a KrF excimer laser can be used to generate several wavelengths with good energy conversion efficiencies by stimulated Raman shifting using hydrogen (H2) and deuterium (D2). Computer simulations for an airborne lidar have shown that these laser emissions can be used for the less than 5 percent random error, high resolution measuremment of ozone across the troposphere using the DIAL technique. In the region of strong ozone absorption, laser wavelengths of 277.0 and 291.7 nm were generated using H2 and D2, respectively. In addition, a laser wavelength at 302.0 nm was generated using two cells in series, with the first containing D2 and the second containing H2. The energy conversion efficiency for each wavelength was between 14 and 27 percent.

Grant, William B.↗
NASA NTRS1991

Investigation of air transportation technology at Ohio University, 1990-1991

The status of the Joint University Program is given. Brief synopsis of some areas of research follow. The study of spectrum efficient methods for transmitting weather information to aircraft has resulted in definition of an improved amplitude and phase modulation process which permits reutilization of voice channels for both voice and data. The system is being implemented for testing. Multisensor navigation systems introduce increased flexibility and performance for aviation, at the expense of increased complexity. Insuring a high level of system reliability and integrity requires that faults not only be detected, but also isolated to specific elements, so that the remaining capabilities of the system may be used with confidence. An algorithm was developed. The JUP has served as a vehicle for reporting work accomplished in evoked potential vision tracking experiments to determine the engineering parameters of this input and control method. Application of GPS in an interferometric mode permits accurate measurement of differential motion; aircraft attitude may be determined using GPS only, with multiple antennas.

Lilley, Robert W.↗
NASA NTRS1999

The Upper Atmosphere Research Satellite: From Coffee Table Art to Quantitative Science

The Upper Atmosphere Research Satellite (UARS) has provided an unprecedented set of observations of constituents of the stratosphere. When used in combination with data from other sources and appropriate modeling tools, these observations are useful for quantitative evaluation of stratospheric photochemical processes. This is illustrated by comparing ozone observations from airborne Differential Absorption Lidar (DIAL), from the Polar Ozone and Aerosol Measurement (POAM), from the Microwave Limb Sounder (MLS), and from the Halogen occultation Experiment (HALOE) with ozone fields generated with a three dimensional model. For 1995-96, at polar latitudes, observations from DIAL flights on December 9 and January 30, and POAM and MLS between late December and late January are compared with ozone fields from the GSFC 3D chemistry and transport model. Data from the three platforms consistently show that the observed ozone has a negative trend relative to the modeled ozone, and that the trend is uniform in time between early and mid winter, with no obvious dependence on proximity to the vortex edge. The importance of chlorine catalyzed photochemistry to this ozone loss is explored by comparing observations from MLS and HALOE with simulations for other northern winters, particularly 1997-98.

Douglass, Anne R.↗
NASA NTRS1999

A Composite View of Lower Stratospheric Ozone Developed Using a Chemistry Transport Model and Observations from Airborne Lidar and Satellite

An ozone simulation from the Goddard three-dimensional chemistry and transport model for the 1995-96 northern hemisphere winter is compared with ozone observations from airborne Differential Absorption Lidar (DIAL), from the Polar Ozone and Aerosol Measurement (POAM), from the Microwave Limb Sounder (MLS), and from the Halogen Occultation Experiment (HALOE). The 3D model uses winds from the Goddard Data Assimilation System. The 3D model reproduces the latitude dependence of the horizontal and vertical ozone gradients of the subtropical DIAL observations. Comparisons with subtropical satellite observations, which lack the spatial resolution of DIAL but provide near continuous coverage throughout the subtropics, show that the model also reproduces longitude and temporal dependence in the tropical-midlatitude boundary. At polar latitudes, observations from DIAL flights on December 9 and January 30, and POAM and MLS between late December and late January are compared with the 3D model. Data from the three platforms consistently show that the observed ozone has a negative trend relative to the modeled ozone, and that the trend is uniform in time between early and mid winter, with no obvious dependence on proximity to the vortex edge.

Douglass, A. R.↗
NASA NTRS1991

Research highlights: June 1990 - May 1991

Linear instability calculations at MSFC have suggested that the Geophysical Fluid Flow Cell (GFFC) should exhibit classic baroclinic instability at accessible parameter settings. Interest was in the mechanisms of transition to temporal chaos and the evolution of spatio-temporal chaos. In order to understand more about such transitions, high resolution numerical experiments for the physically simplest model of two layer baroclinic instability were conducted. This model has the advantage that the numerical code is exponentially convergent and can be efficiently run for very long times, enabling the study of chaotic attractors without the often devastating effects of low-order trunction found in many previous studies. Numerical algorithms for implementing an empirical orthogonal function (EOF) analysis of the high resolution numerical results were completed. Under conditions of rapid rotation and relatively low differential heating, convection in a spherical shell takes place as columnar banana cells wrapped around the annular gap, but with axes oriented along the axis of rotation; these were clearly evident in the GFFC experiments. The results of recent numerical simulations of columnar convection and future research plans are presented.

Source record↗
NASA NTRS1972

Interferometric observations of an artificial satellite.

Very-long-baseline interferometric observations of radio signals from the TACSAT synchronous satellite, even though extending over only 7 hours, have enabled an excellent orbit to be deduced. Precision in differential delay and delay-rate measurements reached 0.15 nanosecond and 0.05 picosecond per second, respectively. The results from this initial three-station experiment demonstrate the feasibility of using the method for accurate satellite tracking and for geodesy.

Preston, R. A.↗
NASA NTRS1986

Vibration of a large space beam under gravity effect

Future space structures will have a low mass density and high flexibility, with ground test dynamic behavior differing significantly from that in zero-G orbit. Attention is presently given to the vibration behavior of a beam deformed by its own weight; the results obtained by the differential equations for both the static and dynamic responses of a large, simply supported beam, which are derived and solved analytically, allow ground test experiment measurements to be used for orbital dynamic characteristics verification efforts.

Shih, C.-F.↗
NASA NTRS1987

Fast-response, high-precision carbon monoxide sensor using a tunable diode laser absorption technique

A tunable diode laser instrument, denoted as DACOM (Differential Absorption CO Measurement), has been developed to meet the fast-response, high-precision CO measurement needs of the GTE (Global Tropospheric Experiment) program. Under the GTE program, DACOM participated in the three field missions of CITE 1 (Chemical Instrumentation Test and Evaluation 1), a project involving the intercomparison of trace gas measurement techniques. DACOM performance, including analyses of measurement error sources, is discussed for the ground-based mission at Wallops Island, VA (summer 1983), and two missions on the NASA CV-990 (fall 1983 and spring 1984). Examples of fast-response (about 1 s), high-precision (+ or - 1 part per billion by volume, + or - 1.5 percent of reading) airborne data are included to illustrate the capability of this instrument.

Sachse, Glen W.↗
NASA NTRS1993

Cellular responses to low-gravity: Pilot studies on suborbital rockets and orbiting spacecraft

The allocated funding supported, in part, experiments conducted on two Consort sounding rockets and five Shuttle flights. The primary parameters investigated were signal transduction in response to various mediators, cellular differentiation and metabolism in microgravity, and effect of microgravity on cytoskeletal morphology. Achievements include: demonstration of effect of spaceflight on the actin cytoskeleton in mouse osteoblasts and frog cells; confirmation that the T cell receptor-mediated signal transduction pathway in T lymphocytes is not affected by low-gravity compared to non-TCR-mediated stimulation (Con-A) which classically does not promote proliferative response; indication that microgravity may allow separation of proliferative signaling and secretory function in lymphocytes; demonstration that T lymphocytes and bone cells utilized less glucose indicating a shift in metabolism and confirming Spacelab results with WI-38 cells which used significantly less glucose, during spaceflight; confirmation that activation of human splenic B cells with a number of different mediators is not affected during spaceflight; demonstration of increased prostaglandin synthesis during reduced bone cell growth suggesting an effect of microgravity on prostaglandin-induced mitogenesis. The funding contributed significantly to the database described above and resulted in submission of six collaborative abstracts in 1993 (five to the ASGSB Annual Meeting and one to the ASCB Annual Meeting). Two abstracts were presented at the 1992 ASGSB Annual Meeting in Tucson. In addition, several peer reviewed papers are being generated and data will be included as background in preparation of future proposals, which hopefully will allow us to continue this type of extremely productive collaborative research.

Lewis, Marian L.↗
NASA NTRS1995

Two-phase flow research using the learjet apparatus

Low-gravity, gas-liquid flow research can be conducted aboard the NASA Lewis Learjet, the Lewis DC-9, or the Johnson Space Center KC-135. Air and water solutions serve as the test liquids in cylindrical test sections with an inner diameter of 1.27 cm and lengths up to 1.5 m. Superficial velocities range from 0.1 to 1.1 m/sec for liquids and from 0.1 to 25 m/sec for air. Flow rate, differential pressure, void fraction, film thickness, wall-shear stress, and acceleration data are measured and recorded throughout the 20 sec duration of the experiment. Flow is visualized by photographing at 400 frames with a high-speed, 16-mm camera.

Mcquillen, John B.↗
NASA NTRS1997

Induction of cyclo-oxygenase-2 mRNA by prostaglandin E2 in human prostatic carcinoma cells

Prostaglandins are synthesized from arachidonic acid by the enzyme cyclo-oxygenase. There are two isoforms of cyclooxygenases: COX-1 (a constitutive form) and COX-2 (an inducible form). COX-2 has recently been categorized as an immediate-early gene and is associated with cellular growth and differentiation. The purpose of this study was to investigate the effects of exogenous dimethylprostaglandin E2 (dmPGE2) on prostate cancer cell growth. Results of these experiments demonstrate that administration of dmPGE2 to growing PC-3 cells significantly increased cellular proliferation (as measured by the cell number), total DNA content and endogenous PGE2 concentration. DmPGE2 also increased the steady-state mRNA levels of its own inducible synthesizing enzyme, COX-2, as well as cellular growth to levels similar to those seen with fetal calf serum and phorbol ester. The same results were observed in other human cancer cell types, such as the androgen-dependent LNCaP cells, breast cancer MDA-MB-134 cells and human colorectal carcinoma DiFi cells. In PC-3 cells, the dmPGE2 regulation of the COX-2 mRNA levels was both time dependent, with maximum stimulation seen 2 h after addition, and dose dependent on dmPGE2 concentration, with maximum stimulation seen at 5 microg ml(-1). The non-steroidal anti-inflammatory drug flurbiprofen (5 microM), in the presence of exogenous dmPGE2, inhibited the up-regulation of COX-2 mRNA and PC-3 cell growth. Taken together, these data suggest that PGE2 has a specific role in the maintenance of human cancer cell growth and that the activation of COX-2 expression depends primarily upon newly synthesized PGE2, perhaps resulting from changes in local cellular PGE2 concentrations.

Non-NASA Center↗
NASA NTRS2013

Demonstration of Detection and Ranging Using Solvable Chaos

Acoustic experiments demonstrate a novel approach to ranging and detection that exploits the properties of a solvable chaotic oscillator. This nonlinear oscillator includes an ordinary differential equation and a discrete switching condition. The chaotic waveform generated by this hybrid system is used as the transmitted waveform. The oscillator admits an exact analytic solution that can be written as the linear convolution of binary symbols and a single basis function. This linear representation enables coherent reception using a simple analog matched filter and without need for digital sampling or signal processing. An audio frequency implementation of the transmitter and receiver is described. Successful acoustic ranging measurements are presented to demonstrate the viability of the approach.

Corron, Ned J.↗
NASA NTRS2016

Clinical Outcome Metrics for Optimization of Robust Training

Introduction: The emphasis of this research is on the Human Research Program (HRP) Exploration Medical Capability's (ExMC) "Risk of Unacceptable Health and Mission Outcomes Due to Limitations of In-Flight Medical Capabilities." Specifically, this project aims to contribute to the closure of gap ExMC 2.02: We do not know how the inclusion of a physician crew medical officer quantitatively impacts clinical outcomes during exploration missions. The experiments are specifically designed to address clinical outcome differences between physician and non-physician cohorts in both near-term and longer-term (mission impacting) outcomes. Methods: Medical simulations will systematically compare success of individual diagnostic and therapeutic procedure simulations performed by physician and non-physician crew medical officer (CMO) analogs using clearly defined short-term (individual procedure) outcome metrics. In the subsequent step of the project, the procedure simulation outcomes will be used as input to a modified version of the NASA Integrated Medical Model (IMM) to analyze the effect of the outcome (degree of success) of individual procedures (including successful, imperfectly performed, and failed procedures) on overall long-term clinical outcomes and the consequent mission impacts. The procedures to be simulated are endotracheal intubation, fundoscopic examination, kidney/urinary ultrasound, ultrasound-guided intravenous catheter insertion, and a differential diagnosis exercise. Multiple assessment techniques will be used, centered on medical procedure simulation studies occurring at 3, 6, and 12 months after initial training (as depicted in the following flow diagram of the experiment design). Discussion: Analysis of procedure outcomes in the physician and non-physician groups and their subsets (tested at different elapsed times post training) will allow the team to 1) define differences between physician and non-physician CMOs in terms of both procedure performance (pre-IMM analysis) and overall mitigation of the mission medical impact (IMM analysis); 2) refine the procedure outcome and clinical outcome metrics themselves; 3) refine or develop innovative medical training products and solutions to maximize CMO performance; and 4) validate the methods and products of this experiment for operational use in the planning, execution, and quality assurance of the CMO training process The team has finalized training protocols and developed a software training/testing tool in collaboration with Butler Graphics (Detroit, MI). In addition to the "hands on" medical procedure modules, the software includes a differential diagnosis exercise (limited clinical decision support tool) to evaluate the diagnostic skills of participants. Human subject testing will occur over the next year.

Ebert, D.↗
NASA NTRS1988

Adaptive independent joint control of manipulators - Theory and experiment

The author presents a simple decentralized adaptive control scheme for multijoint robot manipulators based on the independent joint control concept. The proposed control scheme for each joint consists of a PID (proportional integral and differential) feedback controller and a position-velocity-acceleration feedforward controller, both with adjustable gains. The static and dynamic couplings that exist between the joint motions are compensated by the adaptive independent joint controllers while ensuring trajectory tracking. The proposed scheme is implemented on a MicroVAX II computer for motion control of the first three joints of a PUMA 560 arm. Experimental results are presented to demonstrate that trajectory tracking is achieved despite strongly coupled, highly nonlinear joint dynamics. The results confirm that the proposed decentralized adaptive control of manipulators is feasible, in spite of strong interactions between joint motions. The control scheme presented is computationally very fast and is amenable to parallel processing implementation within a distributed computing architecture, where each joint is controlled independently by a simple algorithm on a dedicated microprocessor.

Seraji, H.↗