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NASA NTRS1992

Development of microcomputer-based mental acuity tests

Recent disasters have focused attention on performance problems due to the use of alcohol and controlled substances in the workplace. Environmental stressors such as thermal extremes, mixed gases, noise, motion, and vibration also have adverse effects on human performance and operator efficiency. However, the lack of a standardized, sensitive, human performance assessment battery has probably delayed the systematic study of the deleterious effects of various toxic chemicals and drugs at home and in the workplace. The collective goal of the research reported here is the development of a menu of tests embedded in a coherent package of hardware and software that may be useful in repeated-measures studies of a broad range of agents that can degrade human performance. A menu of 40 tests from the Automated Performance Test System (APTS) is described, and the series of interlocking studies supporting its development is reviewed. The APTS tests, which run on several versions of laptop portables and desktop personal computers, have been shown to be stable, reliable, and factorially rich, and to have predictive validities with holistic measures of intelligence and simulator performances. In addition, sensitivity studies have been conducted in which performance changes due to stressors, agents, and treatments were demonstrated. We believe that tests like those described here have prospective use as an adjunct to urine testing for the screening for performance loss of individuals who are granted access to workplaces and stations that impact public safety.

Non-NASA Center↗

NASA NTRS2017

Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) Project KDP-C Review

The topics discussed are the UAS-NAS project life-cycle and ARMD thrust flow down, as well as the UAS environments and how we operate in those environments. NASA's Armstrong Flight Research Center at Edwards, CA, is leading a project designed to help integrate unmanned air vehicles into the world around us. The Unmanned Aircraft Systems Integration in the National Airspace System project, or UAS in the NAS, will contribute capabilities designed to reduce technical barriers related to safety and operational challenges associated with enabling routine UAS access to the NAS. The project falls under the Integrated Systems Research Program office managed at NASA Headquarters by the agency's Aeronautics Research Mission Directorate. NASA's four aeronautics research centers - Armstrong, Ames Research Center, Langley Research Center, and Glenn Research Center - are part of the technology development project. With the use and diversity of unmanned aircraft growing rapidly, new uses for these vehicles are constantly being considered. Unmanned aircraft promise new ways of increasing efficiency, reducing costs, enhancing safety and saving lives 460265main_ED10-0132-16_full.jpg Unmanned aircraft systems such as NASA's Global Hawks (above) and Predator B named Ikhana (below), along with numerous other unmanned aircraft systems large and small, are the prime focus of the UAS in the NAS effort to integrate them into the national airspace. Credits: NASA Photos 710580main_ED07-0243-37_full.jpg The UAS in the NAS project envisions performance-based routine access to all segments of the national airspace for all unmanned aircraft system classes, once all safety-related and technical barriers are overcome. The project will provide critical data to such key stakeholders and customers as the Federal Aviation Administration and RTCA Special Committee 203 (formerly the Radio Technical Commission for Aeronautics) by conducting integrated, relevant system-level tests to adequately address safety and operational challenges of national airspace access by unmanned aircraft systems, or UAS. In the process, the project will work with other key stakeholders to define necessary deliverables and products to help enable such access. Within the project, NASA is focusing on five sub-projects. These five focus areas include assurance of safe separation of unmanned aircraft from manned aircraft when flying in the national airspace; safety-critical command and control systems and radio frequencies to enable safe operation of UAS; human factors issues for ground control stations; airworthiness certification standards for UAS avionics and integrated tests and evaluation designed to determine the viability of emerging UAS technology. Five Focus Areas of the UAS Integration in the NAS Project Separation Assurance Provide an assessment of how planned Next Generation Air Transportation System (NextGen) separation assurance systems, with different functional allocations, perform for UAS in mixed operations with manned aircraft Assess the applicability to UAS and the performance of NASA NextGen separation assurance systems in flight tests with realistic latencies and uncertain trajectories Assess functional allocations ranging from today's ground-based, controller-provided aircraft separation to fully autonomous airborne self-separation Communications Develop data and rationale to obtain appropriate frequency spectrum allocations to enable safe and efficient operation of UAS in the NAS Develop and validate candidate secure safety-critical command and control system/subsystem test equipment for UAS that complies with UAS international/national frequency regulations, standards and recommended practices and minimum operational and aviation system performance standards for UAS Perform analysis to support recommendations for integration of safety-critical command and control systems and air traffic control communications to ensure safe and efficient operation of UAS in the NAS Human Systems Integration Develop a research test bed and database to provide data and proof of concept for GCS - ground control station - operations in the NAS Coordinate with standards organizations to develop human-factors guidelines for GCS operation in the NAS Certification Define a UAS classification scheme and approach to determining Federal Aviation Regulation airworthiness requirements applicable to all UAS digital avionics Provide hazard and risk-related data to support development of type design criteria and best development practices Integrated Tests and Evaluation Integrate and test mature concepts from technical elements to demonstrate and test viability Evaluate the performance of technology development in a relevant environment (full-mission, human-in-the-loop simulations and flight tests)

outreach↗

NASA NTRSDate not supplied

Test Capabilities of the NASA Langley Direct Connect Supersonic Combustion Test Facility

In 1969 a combustion-heated direct-connect test facility was assembled at the NASA Langley Research Center and used to support NASA’s Hypersonic Research Engine program. Later, the facility was used to support NASA’s generic hypersonic program, assessing the mixing, ignition, flame holding, and combustion characteristics of ramjet and scramjet combustors. Over the years, the facility has been updated and modified to conduct increasingly complicated tests. Today, the facility is known as the Direct Connect Supersonic Combustion Test Facility (DCSCTF) and is part of the NASA Langley Scramjet Test Complex. Recently, the facility has been used by external customers to test fuel-cooled and uncooled, flight-like test articles. Tests have been conducted at nominal Mach 5 flight conditions for up to 15 minutes of continuous operation. The facility remains a viable and useful tool in the support of various Department of Defense projects.

Diego P Capriotti↗

NASA NTRS1994

Optimization of Orifice Geometry for Cross-Flow Mixing in a Cylindrical Duct

Mixing of gaseous jets in a cross-flow has significant applications in engineering, one example of which is the dilution zone of a gas turbine combustor. Despite years of study, the design of jet injection in combustors is largely based on practical experience. A series of experiments was undertaken to delineate the optimal mixer orifice geometry. A cross-flow to core-flow momentum-flux ratio of 40 and a mass flow ratio of 2.5 were selected as representative of an advanced design. An experimental test matrix was designed around three variables: the number of orifices, the orifice aspect ratio (long-to-short dimension), and the orifice angle. A regression analysis was performed on the data to arrive at an interpolating equation that predicted the mixing performance of orifice geometry combinations within the range of the test matrix parameters. Results indicate that mixture uniformity is a non-linear function of the number of orifices, the orifice aspect ratio, and the orifice angle. Optimum mixing occurs when the asymptotic mean jet trajectories are in the range of 0.35 less than r/R less than 0.5 (where r = 0 is at the mixer wall) at z/R = 1.0. At the optimum number of orifices, the difference between shallow-angled slots with large aspect ratios and round holes is minimal and either approach will lead to good mixing performance. At the optimum number of orifices, it appears possible to have two local optimums where one corresponds to an aspect ratio of 1.0 and the other to a high aspect ratio.

Sowa, W. A.↗

NASA NTRSDate not supplied

Lunar Impact Melt Crystallization Produces Reflectance Spectra Dominated By Clinopyroxene Signatures: Implications for the Origin of Pink Spinel Anorthosite

Magma-wallrock interaction and impact melt crystallization are the two leading hypotheses for the formation of orbitally detected lunar “pink” spinel anorthosite (PSA) [1-3]. Distinguishing among hypotheses is complicated because both require mixing of anorthositic crust and MgO-rich ultramafic components. Models for PSA formation need to account for either the thermodynamic hurdles of crustal assimilation, or the size of impactor and composition of target material needed to generate spinel during crater and basin formation. Determining whether the energy source is endogenic or exogenic is important for understanding the thermal and chemical evolution of the lunar crust. Here we test the impact melt hypothesis by performing controlled cooling experiments on two hypothetical impact melt compositions. The compositions represent mixing of ultramafic magma and anorthositic crust in molar ratios of approximately 50:50 and 25:75. Synthetic crystallized assemblages were prepared for chemical analysis and bidirectional reflectance spectroscopy in the visible to near-infrared wavelengths. All crystallization experiments contained plagioclase, olivine, and clinopyroxene, but trace amounts of spinel were only observed in the 50:50 mix. The experimental spinel is similar to the compositions inferred from remote observations. However, the high-Ca pyroxene in our experimental assemblages (9 – 18 wt.%) resulted in 1 and 2 µm absorption band center positions consistent with synthetic clinopyroxene. The clinopyroxene absorptions are present regardless of specific mineral modes and the presence of either olivine or spinel. These results suggest that impact melt crystallization will produce clinopyroxene-bearing lithologies, the presence of which masks spectral contributions from coexisting spinel and olivine. Assuming that the trace amounts of spinel observed in our experiments could be concentrated and isolated from the mafic silicates by convection or density settling in the impact melt sheet, the spinel-rich areas would still be proximally associated with the remaining silicate-dominated assemblage exhibiting strong clinopyroxene spectral signatures. We conclude that impact melting of the lunar crust can explain rare cases of PSA in association with clinopyroxene. Previous investigations of magma-wallrock interactions [2] demonstrate that small plagioclase-contaminated regions of an ultramafic intrusion can concentrate spinel whereas larger portions of the same intrusion remain relatively uncontaminated and yield olivine and orthopyroxene, consistent with the more common occurrence of PSAs in association with orthopyroxene ±olivine in the remote sensing database (e.g., Moscoviense Basin) [4].

petrology↗

NASA NTRS1992

Signal processing for airborne doppler radar detection of hazardous wind shear as applied to NASA 1991 radar flight experiment data

Radar data collected during the 1991 NASA flight tests have been selectively analyzed to support research directed at developing both improved as well as new algorithms for detecting hazardous low-altitude windshear. Analysis of aircraft attitude data from several flights indicated that platform stability bandwidths were small compared to the data rate bandwidths which should support an assumption that radar returns can be treated as short time stationary. Various approaches at detection of weather returns in the presence of ground clutter are being investigated. Non-coventional clutter rejection through spectrum mode tracking and classification algorithms is a subject of continuing research. Based upon autoregressive modeling of the radar return time sequence, this approach may offer an alternative to overcome errors in conventional pulse-pair estimates. Adaptive filtering is being evaluated as a means of rejecting clutter with emphasis on low signal-to-clutter ratio situations, particularly in the presence of discrete clutter interference. An analysis of out-of-range clutter returns is included to illustrate effects of ground clutter interference due to range aliasing for aircraft on final approach. Data are presented to indicate how aircraft groundspeed might be corrected from the radar data as well as point to an observed problem of groundspeed estimate bias variation with radar antenna scan angle. A description of how recorded clutter return data are mixed with simulated weather returns is included. This enables the researcher to run controlled experiments to test signal processing algorithms. In the summary research efforts involving improved modelling of radar ground clutter returns and a Bayesian approach at hazard factor estimation are mentioned.

Baxa, Ernest G., Jr.↗

NASA NTRS1993

Proposed system safety design and test requirements for the microlaser ordnance system

Safety for pyrotechnic ignition systems is becoming a major concern for the military. In the past twenty years, stray electromagnetic fields have steadily increased during peacetime training missions and have dramatically increased during battlefield missions. Almost all of the ordnance systems in use today depend on an electrical bridgewire for ignition. Unfortunately, the bridgewire is the cause of the majority of failure modes. The common failure modes include the following: broken bridgewires; transient RF power, which induces bridgewire heating; and cold temperatures, which contracts the explosive mix away from the bridgewire. Finding solutions for these failure modes is driving the costs of pyrotechnic systems up. For example, analyses are performed to verify that the system in the environment will not see more energy than 20 dB below the 'No-fire' level. Range surveys are performed to determine the operational, storage, and transportation RF environments. Cryogenic tests are performed to verify the bridgewire to mix interface. System requirements call for 'last minute installation,' 'continuity checks after installation,' and rotating safety devices to 'interrupt the explosive train.' As an alternative, MDESC has developed a new approach based upon our enabling laser diode technology. We believe that Microlaser initiated ordnance offers a unique solution to the bridgewire safety concerns. For this presentation, we will address, from a system safety viewpoint, the safety design and the test requirements for a Microlaser ordnance system. We will also review how this system could be compliant to MIL-STD-1576 and DOD-83578A and the additional necessary requirements.

Stoltz, Barb A.↗

NASA NTRS1974

Distributed educated throat stability bypass to increase the stable airflow range of a Mach 2.5 inlet with 60-percent internal contraction

The results of an experimental investigation to increase the stable airflow operating range of a supersonic mixed-compression inlet are presented. A distributed educated throat stability-bypass entrance configuration was tested. In terms of diffuser-exit corrected airflow, a large inlet stable airflow range of about 16.1 percent was obtained if a constant pressure was maintained in the bypass plenum. Limited unstart angle of attack data are presented.

Shaw, R. J.↗

NASA NTRS1973

An optimum organizational structure for a large earth-orbiting multidisciplinary Space Base

The purpose of this exploratory study was to identify an optimum hypothetical organizational structure for a large earth-orbiting multidisciplinary research and applications (R&A) Space Base manned by a mixed crew of technologists. Since such a facility does not presently exist, in situ empirical testing was not possible. Study activity was, therefore, concerned with the identification of a desired organizational structural model rather than the empirical testing of it. The essential finding of this research was that a four-level project type 'total matrix' model will optimize the efficiency and effectiveness of Space Base technologists.

Ragusa, J. M.↗

NASA NTRS1974

Studies on propagation of microbes in the airborne state

An investigation was conducted to demonstrate whether airborne microbes could propagate. The procedure consisted of: (1) looking for dilution of a labelled base in DNA; (2) looking for labelling of DNA by mixing aerosols of the label and the cells; (3) examining changes in cell size; (4) testing the possibility of spore germination; and (5) seeking evidence of an increase in cell number. Results indicate that growth and propagation can occur under special conditions, principally at temperatures of approximately 30 C (87 F) and water activity equivalents of 0.95 to 0.98.

Dimmick, R. L.↗

NASA NTRS1975

Development of space stable thermal control coatings for use on large space vehicles

Pigment manufacturing development, binder development, environmental effects evaluations, and general coatings investigations are discussed. The relative emphasis on each of these tasks varied according to the urgency of the problems elucidated and the availability of time and funds. Emphasis is placed on the development of a mixed oxalate precursor zinc orthotitanate pigment manufacturing method and related studies and on complementary environmental testing and evaluation activities.

Harada, Y.↗

NASA NTRS1980

Using LANDSAT digital data for estimating green biomass

The author has identified the following significant results. Relationships between the quantity of mixed prairie rangeland vegetation and LANDSAT MSS response were studied during four growing seasons at test sites throughout the United States Great Plans region. A LANDSAT derived parameter, the normalized difference was developed from theoretical considerations fro statistical estimation of the amount and seasonal condition of rangeland vegetation. This parameter was tested for application to local assessment of green forage biomass and regional monitoring of range feed conditions and drought. Results show that for grasslands in the Great Plains with near continuous vegetative cover and free of heavy brush and forbs, the LANDSAT digital data can provide a useful estimate of the quantity of green forage biomass (within 250 kg/ha), and at least five levels of pasture and range feed conditions can be adequately mapped for extended regions.

Deering, D. W.↗

NASA NTRS1982

The Apollo 15 regolith - Chemical modeling and mare/highland mixing

The chemical compositions of thirty-one A-15 soils from nine sampling stations were studied. Mixing models were calculated using five components: 'representative A-15 mare basalt', anorthosite, low-K Fra Mauro basalt, green glass, and medium-K KREEP (Laul and Papike, 1980). A linear-least-squares mixing model (Boynton et al., 1975) was used with sum check and chi-square tests of the fit of components to soil composition. The soils show significant compositional variability, in some instances over relatively small distances within a sampling station. The models indicate that green-glass abundance does not vary systematically with location and that a significant KREEP component is found in all Apennine Front soils. The models also show the soils from the rim of Hadley Rille to be the most mare-enriched, and soils from Station 2 to be the most highland-enriched. The regolith from Station 8-LM is anomalously high in KREEP component relative to the other mare soils, possibly because of ray material.

Walker, R. J.↗

NASA NTRS1982

Evaluation of fuel injection configurations to control carbon and soot formation in small GT combustors

An experimental program to investigate hardware configurations which attempt to minimize carbon formation and soot production without sacrificing performance in small gas turbine combustors has been conducted at the United Technologies Research Center. Four fuel injectors, embodying either airblast atomization, pressure atomization, or fuel vaporization techniques, were combined with nozzle air swirlers and injector sheaths, and evaluated at test conditions which included and extended beyond standard small gas turbine combustor operation. Extensive testing was accomplished with configurations embodying either a spill return or a T-vaporizer injector. Minimal carbon deposits were observed on the spill return nozzle for tests using either Jet A or ERBS test fuel. A more extensive film of soft carbon was observed on the vaporizer after operation at standard engine conditions, with large carbonaceous growths forming on the device during off-design operation at low combustor inlet temperature. Test results indicated that smoke emission levels depended on the combustor fluid mechanics (especially the mixing rates near the injector), the atomization quality of the injector and the fuel hydrogen content.

Rosfjord, T. J.↗

NASA NTRS1985

SCARE: A post-processor program to MSC/NASTRAN for the reliability analysis of structural ceramic components

A computer program was developed for calculating the statistical fast fracture reliability and failure probability of ceramic components. The program includes the two-parameter Weibull material fracture strength distribution model, using the principle of independent action for polyaxial stress states and Batdorf's shear-sensitive as well as shear-insensitive crack theories, all for volume distributed flaws in macroscopically isotropic solids. Both penny-shaped cracks and Griffith cracks are included in the Batdorf shear-sensitive crack response calculations, using Griffith's maximum tensile stress or critical coplanar strain energy release rate criteria to predict mixed mode fracture. Weibull material parameters can also be calculated from modulus of rupture bar tests, using the least squares method with known specimen geometry and fracture data. The reliability prediction analysis uses MSC/NASTRAN stress, temperature and volume output, obtained from the use of three-dimensional, quadratic, isoparametric, or axisymmetric finite elements. The statistical fast fracture theories employed, along with selected input and output formats and options, are summarized. An example problem to demonstrate various features of the program is included.

Gyekenyesi, J. P.↗

NASA NTRS1986

Numerical analysis of SSME preburner injector atomization and combustion processes

The coaxial spray injection and combustion flowfields of a Space Shuttle Main Engine preburner injector element have been analyzed using a three-phase numerical code. The processes of atomization, evaporation, secondary droplet breakup, and multispecies chemistry, as well as turbulent diffusion, are included. The model produced realistic pictures of the complex internal flowfield, including liquid jet length, spray shape, flame-zone size and characteristics, and predicted temperatures that seem to be in agreement with test data envelopes. It predicted an external group combustion type of flame. Salient combustion and mixing features are discussed and sources of uncertainty are pointed out for future studies.

Liang, P. Y.↗

NASA NTRS1986

SCARE - A postprocessor program to MSC/NASTRAN for reliability analysis of structural ceramic components

Gyekenyesi, J. P.↗

NASA NTRS1986

A model for the use of satellite remote sensing for the measurement of primary production in the ocean

A model of primary production based upon the responses of phytoplankton to differing light and nutrient fields is described. This model includes the effects on production of variations in surface pigment concentration, the mixed layer depth, and the dependence on the incident solar irradiance. The model has been tested using in situ data provided by the Southern California Bight Studies of Eppley, et al. (1979), the California Cooperative Fisheries Investigations, the Organization of Persistent Upwelling Structures, and other data sets. A synoptic measure of the distribution of surface pigments is derived from the West Coast Chlorophyll and Temperature Time Series. The features and behavior of the model are presented together with the results of the model verification.

Collins, Donald J.↗