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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

A software system for emission spectrometry

A computer system was developed for an emission spectrometry facility consisting of a direct current (DC) argon arc spectrograph optically coupled to an inductively coupled plasma multichannel spectrometer. Custom hardware and software were designed to control analytical functions and perform data acquisition. The software system was designed to make operation of the facility simple for routine operation and flexible for research and development. Special software was written to collect data under controlled conditions to characterize and monitor system response. One sequence collects intensity versus time data on all channels and displays the data graphically. These profiles are useful in studying the effects of operating parameters on measurement precision. Another special sequence performs calibration using a spline curve fit procedure. Routines were also written to measure dark currents and signals from a standard tungsten halogen lamp mounted in place of the DC arc. For quality control purposes, histories of these values are kept and monitored for excess scatter or drift.

Auping, J. V.↗
NASA NTRS1989

Parametric study of a simultaneous pitch/yaw thrust vectoring single expansion ramp nozzle

In the course of the last eleven years, the concept of thrust vectoring has emerged as a promising method of enhancing aircraft control capabilities in post-stall flight incursions during combat. In order to study the application of simultaneous pitch and yaw vectoring to single expansion ramp nozzles, a static test was conducted in the NASA-Langley 16 foot transonic tunnel. This investigation was based on internal performance data provided by force, mass flow and internal pressure measurements at nozzle pressure ratios up to 8. The internal performance characteristics of the nozzle were studied for several combinations of six different parameters: yaw vectoring angle, pitch vectoring angle, upper ramp cutout, sidewall hinge location, hinge inclination angle and sidewall containment. Results indicated a 2-to- 3-percent decrease in resultant thrust ratio with vectoring in either pitch or yaw. Losses were mostly associated with the turning of supersonic flow. Resultant thrust ratios were also decreased by sideways expansion of the jet. The effects of cutback corners in the upper ramp and lower flap on performance were small. Maximum resultant yaw vector angles, about half of the flap angle, were achieved for the configuration with the most forward hinge location.

Schirmer, Alberto W.↗
NASA NTRS1995

The effects of Crew Resource Mangement (CRM) training in airline maintenance: Results following three years' experience

This report describes three years' evaluation of the effects of one airline's Crew Resources Management (CRM) training operation for maintenance. This evaluation focuses on the post-training attitudes of maintenance managers' and technical support professionals, their reported behaviors, and the safety, efficiency and dependable maintenance performance of their units. The results reveal a strong positive effect of the training. The overall program represents the use of CRM training as a long-term commitment to improving performance through effective communication at all levels in airline maintenance operations. The initial findings described in our previous progress reports are reinforced and elaborated here. The current results benefit from the entire pre-post training survey, which now represents total attendance of all managers and staff professionals. Additionally there are now full results from the two-month, six-month, and 12-month follow-up questionnaires, together with as many as 33 months of post-training performance data, using several indicators. In this present report, we examine participants' attitudes, their reported behaviors following the training, the performance of their work units, and the relationships among these variables. Attitudes include those measured immediately before and after the training as well as participants' attitudes months after their training. Performance includes measures, by work units, of on-time flight departures, on-schedule maintenance releases, occupational and aircraft safety, and efficient labor costs. We report changes in these performance measures following training, as well their relationships with the training participants' attitudes. Highlights of results from this training program include increased safety and improved costs associated with positive attitudes about the use of more assertive communication, and the improved management of stress. Improved on-time performance is also related to those improved attitudes, as well as favorable attitudes about participative management.

Taylor, J. C.↗
NASA NTRSDate not supplied

Countermeasures for Mitigation of Sensorimotor Decrements Following Head-Down Bed Rest

BACKGROUND Astronauts experience postflight disturbances in postural and locomotor control due to sensorimotor adaptations during spaceflight. These alterations may have adverse consequences if a rapid egress is required after landing. Although exercise is partially effective for mitigating cardiovascular and muscular deconditioning, additional countermeasures are needed to further preserve sensorimotor function for exploration missions. We have identified proprioceptive training and electrical muscle stimulation (EMS) as promising in-flight countermeasures. Since prolonged head down bed rest (HDBR) is a spaceflight analog for body unloading and causes postural and locomotor control decrements that parallel those observed after spaceflight, it can be used to accelerate the development of these countermeasures. METHODS This study will determine the effects of proprioceptive training and EMS on functional task performance and sensorimotor function following 60 days of 6° HDBR. Subjects will be randomly assigned to one of four groups: 1) an EMS arm, 2) a proprioceptive training arm, 3) an exercise plus proprioceptive training arm, and 4) a control arm. The EMS countermeasure will include daily bilateral stimulation of the quadriceps femoris muscle (30 minutes per session). Proprioceptive training will be performed three days per week (20 minutes per session) consisting of body-loaded postural tasks in the horizontal position on an air bearing sled. Exercise training will mimic current protocols used on the International Space Station, but treadmill aerobic exercise will be replaced with additional cycling aerobic exercise. Primary outcome measures will include pre and post HDBR functional tests that are representative of high priority exploration mission tasks and require high demand for dynamic control of postural stability. Additional measures will be used to identify the key physiological factors contributing to countermeasure benefits. Given the constrained samples size, a Bayesian modelling approach will be used to quantify the probability that there is an effect of a given magnitude. COUNTERMEASURE UPDATES Proprioceptive countermeasure design enhancements and human in the loop pilot testing continued through the Crew Health Countermeasures (CHC) Systems Capability Leadership Team (SCLT). The primary goals of this work were to enhance the visual feedback system’s capabilities and develop a proprioceptive training program for 60 days of HDBR. Six healthy non-astronaut volunteers participated in four pilot training sessions to systematically examine how each training variable (e.g., axial load, foot placement, and software profile) affects the overall proprioceptive challenge. The resulting training program will maintain an appropriate challenge during 60 days of HDBR by progressively decreasing the subject’s base of support, increasing tilt board target distances, and increasing axial loads using both subjective verbal feedback and objective performance data. RELEVANCE The deliverable from this project will be proof-of-concept sensorimotor countermeasure designs for functional task performance with full assessment of efficacy in a spaceflight analog. If the countermeasures are effective, they will be translated for validation with the suite of operationally implemented in-flight countermeasures.

T R Macaulay↗
NASA NTRSDate not supplied

An Oveview of TROPESS Data Products and Services at the NASA GES DISC

The TRopospheric Ozone and Precursors from Earth System Sounding (TROPESS) project generates Earth System Data Records (ESDRs) of ozone, and other atmospheric constituents (CH4,CO, H2O, HDO, NH3, PAN and temperature) by processing data from multiple satellites through a common retrieval algorithm and ground data system. Satellite Level-1B input data used in generating the TROPESS L2 data products include CrIS NOAA-20 (JPSS-1), CrIS SNPP, AIRS Aqua, OMI Aura, and TROPOMI S5P. The common retrieval framework is known as the MUlti-SpEctra, MUlti-SpEcies, Multi-SEnsors (MUSES) science data processing system (MUSES-SDPS). Several of the TROPESS data products are now available from the NASA Goddard Earth Sciences Data and Information Service Center (GES DISC) for users to download. In this presentation we provide an overview of the various TROPESS data products. These data products can be divided into the following Forward Stream types: Standard Products, Summary Products, and Full-Archival Products. Standard Products are for users that are doing full analysis with avenging kernel and covariance corresponding to retrieved vertical profiles. Summary products have a smaller file size and are more convenient for first-look and rapid analysis, include total and partial columns, as well as column averaging kernels. The Full-Archival Products will contain all information used in creating the data. TROPESS also creates Special Products, provided on an as-needed and as-available basis to support NASA field missions and individual-investigator requests over specific regions. Eventually, TROPESS will also produce and deliver a set of Reanalysis Stream products. Data at the GES DISC are being transitioned into the "Cloud". This will allow users with "Cloud” access to perform data analysis directly on the data without downloading the data to their system. Services, such as subsetting and data visualization, will also be provided for TROPESS data products at the GES DISC.

James Johnson↗
NASA NTRS1999

The Airline Quality Rating 1999

The Airline Quality Rating (AQR) was developed and first announced in early 1991 as an objective method of comparing airline performance on combined multiple criteria. This current report, Airline Quality Rating 1999, reflects an updated approach to calculating monthly Airline Quality Rating scores for 1998. AQR scores for the calendar year 1998 are based on 15 elements that focus on airline performance areas important to air travel consumers. The Airline Quality Rating is a summary of month-by-month quality ratings for the ten major U.S. airlines operating during 1998. Using the Airline Quality Rating system of weighted averages and monthly performance data in the areas of on-time arrivals, involuntary denied boardings, mishandled baggage, and a combination of 12 customer complaint categories, major airlines comparative performance for the calendar year 1998 is reported. This research monograph contains a brief summary of the AQR methodology, detailed data and charts that track comparative quality for major airlines domestic operations for the 12 month period of 1998, and industry average results. Also, comparative Airline Quality Rating data for 1997, using the updated criteria, are included to provide a reference point regarding quality in the industry.

Bowen, Brent D.↗
NASA NTRS2009

Assessment of the 802.11g Wireless Protocol for Lunar Surface Communications

Future lunar surface missions supporting the NASA Vision for Space Exploration will rely on wireless networks to transmit voice and data. The ad hoc network architecture is of particular interest since it does not require a complex infrastructure. In this report, we looked at data performance over an ad hoc network with varying distances between Apple AirPort wireless cards. We developed a testing program to transmit data packets at precise times and then monitored the receive time to characterize connection delay, packet loss, and data rate. Best results were received for wireless links of less than 75 ft, and marginally acceptable (25-percent) packet loss was received at 150 ft. It is likely that better results will be obtained on the lunar surface because of reduced radiofrequency interference; however, higher power transmitters or receivers will be needed for significant performance gains.

Chelmins, David T.↗
NASA NTRS2002

Dual Purpose Simulation: New Data Link Test and Performance Limit Testing of Currently Deployed Data Link

While the results of this paper are similar to those of [I], in this paper technical difficulties present in [I] are eliminated, producing better results, enabling one to more readily see the benefits of Prioritized CSMA (PCSMA). A new analysis section also helps to generalize this research so that it is not limited to exploration of the new concept of PCSMA. Commercially available network simulation software, OPNET version 7.0, simulations are presented involving an important application of the Aeronautical Telecommunications Network (ATN), Controller Pilot Data Link Communications (CPDLC) over the Very High Frequency Data Link Mode 2 (VDL-2). Communication is modeled for essentially all incoming and outgoing nonstop air-traffic for just three United States cities: Cleveland, Cincinnati, and Detroit. The simulation involves 111 Air Traffic Control (ATC) ground stations, 32 airports distributed throughout the U.S., which are either sources or destinations for the air traffic landing or departing from the three cities, and also 1,235 equally equipped aircraft-taking off, flying realistic free-flight trajectories, and landing in a 24-hr period. Collision-less PCSMA is successfully tested and compared with the traditional CSMA typically associated with VDL-2. The performance measures include latency, throughput, and packet loss. As expected, PCSMA is much quicker and more efficient than traditional CSMA. These simulation results show the potency of PCSMA for implementing low latency, high throughput and efficient connectivity. Moreover, since PCSMA outperforms traditional CSMA, by simulating with it, we can determine the limits of performance beyond which traditional CSMA may not pass. So we have the tools to determine the traffic-loading conditions where traditional CSMA will fail, and we are testing a new and better data link that could replace it with relative ease. Work is currently being done to drastically expand the number of flights to make the simulation more representative of the National Aerospace System.

Robinson, Daryl C.↗
NASA NTRS2006

Comanche Helmet-Mounted Display Heading-Tape Simulation

The Aeroflightdynamics Directorate (AMRDEC) conducted a simulation to assess the performance associated with a Contact Analog, world-referenced heading tape as implemented on the Comanche Helmet Integrated Display Sight System (HIDSS) when compared with a Compressed heading tape similar to that specified by the former Military Standard (MIL-STD) 1295. Six experienced pilots flew three modified Aeronautical Design Standards (ADS)-33 maneuvers (Hover Turn, Bob-up, Transient Turn) and a precision traffic pattern in the NASA Vertical Motion Simulator (VMS). Analysis of the pilot objective performance data and subjective handling qualities ratings (HQRs) showed the following: Compressed symbology in the Velocity Stabilization (VelStab) flight mode generally produced the most precise performances over Contact Analog symbology with respect to the heading, altitude, position, and time criteria specified for the maneuvers tested. VelStab outperformed the Automatic Flight Control System (AFCS) on all maneuvers achieving desired performance on most maneuvers for both symbol sets. Performance in the AFCS mode was generally desirable to adequate for heading and altitude and did not meet adequate standards for hover position and time for the Hover Turn and Bob-up maneuvers. VelStab and AFCS performance were nearly the same for the Transient Turn. Pilot comments concerning the Contact Analog heading-tape implementation were generally unfavorable in spite of the achieved levels of performance. HQRs showed Compressed symbology in the VelStab flight mode produced the lowest mean HQR, encompassing mixed ratings of satisfactory handling and needing improvement. All other symbology/flight-mode combinations yielded higher HQRs, which characterized opinions that deficiencies in aircraft handling due to HMD symbology would need improvement. Contact Analog heading tape and other symbology require improvement, especially when operating in the AFCS mode. NASA-TLX rated Compressed symbology in the VelStab flight mode as the least demanding on resources, closely followed by ratings for Contact Analog in the VelStab mode. In a similar pattern, TLX ratings for maneuvers completed in the AFCS mode yielded a higher level of resource demand with even slighter differences between Contact Analog and Compressed symbology sets. Further research should be conducted where objective data and subjective HQR ratings indicate a need for improvement. The areas requiring attention are those where the symbology implementation, the flight control system, or a combination of both caused workload to reach an objectionable level where adequate performance was either difficult to achieve or unachievable. These areas are clearly identified in this report. Symbology that received negative HQR comments by a majority of pilots should also be examined. The summary of pilot comments can be found in appendix A. Additional simulation trials should be considered to address the identified issues.

Turpin, Terry↗
NASA NTRS1977

Heterojunctions in photovoltaic devices

Heterojunctions have interesting optical properties which make them attractive for solar cells. Several types of heterostructure solar cells have been investigated: heteroface, abrupt heterojunction, and graded-gap heterojunction solar cells. The primary advantage of heterostructure cells is the enhanced short-wavelength response although there is potential for low-cost cells with polycrystalline material. The improvement in solar-cell performance for heterojunctions depends upon the selection of semiconductors with useful energy gaps that are closely matched in lattice-spacing and thermal-expansion coefficients. The importance of the heterojunction interface and its dependence on material properties is discussed. Various fabrication methods are discussed and their application to the different types of heterostructures. Recent performance data for material systems representative of each type of heterostructure cell are discussed and considered in terms of maximum expected performance.

Feucht, D. L.↗
NASA NTRS1999

Computational Investigation of Fluidic Counterflow Thrust Vectoring

A computational study of fluidic counterflow thrust vectoring has been conducted. Two-dimensional numerical simulations were run using the computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. For validation, computational results were compared to experimental data obtained at the NASA Langley Jet Exit Test Facility. In general, computational results were in good agreement with experimental performance data, indicating that efficient thrust vectoring can be obtained with low secondary flow requirements (less than 1% of the primary flow). An examination of the computational flowfield has revealed new details about the generation of a countercurrent shear layer, its relation to secondary suction, and its role in thrust vectoring. In addition to providing new information about the physics of counterflow thrust vectoring, this work appears to be the first documented attempt to simulate the counterflow thrust vectoring problem using computational fluid dynamics.

Hunter, Craig A.↗
NASA NTRS2005

A Multi-scale Approach to Urban Thermal Analysis

An environmental consequence of urbanization is the urban heat island effect, a situation where urban areas are warmer than surrounding rural areas. The urban heat island phenomenon results from the replacement of natural landscapes with impervious surfaces such as concrete and asphalt and is linked to adverse economic and environmental impacts. In order to better understand the urban microclimate, a greater understanding of the urban thermal pattern (UTP), including an analysis of the thermal properties of individual land covers, is needed. This study examines the UTP by means of thermal land cover response for the Salt Lake City, Utah, study area at two scales: 1) the community level, and 2) the regional or valleywide level. Airborne ATLAS (Advanced Thermal Land Applications Sensor) data, a high spatial resolution (10-meter) dataset appropriate for an environment containing a concentration of diverse land covers, are used for both land cover and thermal analysis at the community level. The ATLAS data consist of 15 channels covering the visible, near-IR, mid-IR and thermal-IR wavelengths. At the regional level Landsat TM data are used for land cover analysis while the ATLAS channel 13 data are used for the thermal analysis. Results show that a heat island is evident at both the community and the valleywide level where there is an abundance of impervious surfaces. ATLAS data perform well in community level studies in terms of land cover and thermal exchanges, but other, more coarse-resolution data sets are more appropriate for large-area thermal studies. Thermal response per land cover is consistent at both levels, which suggests potential for urban climate modeling at multiple scales.

Gluch, Renne↗
NASA NTRS2007

Online Analysis Enhances Use of NASA Earth Science Data

Giovanni, the Goddard Earth Sciences Data and Information Services Center (GES DISC) Interactive Online Visualization and Analysis Infrastructure, has provided researchers with advanced capabilities to perform data exploration and analysis with observational data from NASA Earth observation satellites. In the past 5-10 years, examining geophysical events and processes with remote-sensing data required a multistep process of data discovery, data acquisition, data management, and ultimately data analysis. Giovanni accelerates this process by enabling basic visualization and analysis directly on the World Wide Web. In the last two years, Giovanni has added new data acquisition functions and expanded analysis options to increase its usefulness to the Earth science research community.

Acker, James G.↗
NASA NTRS2005

Effect of contrast on the active control of a moving line

In many passive visual tasks, human perceptual judgments are contrast dependent. To explore whether these contrast dependencies of visual perception also affect closed-loop manual control tasks, we examined visuomotor performance as humans actively controlled a moving luminance-defined line over a range of contrasts. Four subjects were asked to use a joystick to keep a horizontal line centered on a display as its vertical position was perturbed by a sum of sinusoids under two control regimes. The total root mean square (RMS) position error decreased quasi-linearly with increasing log contrast across the tested range (mean slope across subjects: -8.0 and -7.7% per log2 contrast, for the two control regimes, respectively). Frequency-response (Bode) plots showed a systematic increase in open-loop gain (mean slope: 1.44 and 1.30 dB per log2 contrast, respectively), and decrease in phase lag with increasing contrast, which can be accounted for by a decrease in response time delay (mean slope: 32 and 40 ms per log2 contrast, respectively). The performance data are well fit by a Crossover Model proposed by McRuer and Krendel, which allowed us to identify both visual position and motion cues driving performance. This analysis revealed that the position and motion cues used to support manual control under both control regimes appear equally sensitive to changes in stimulus contrast. In conclusion, our data show that active control of a moving visual stimulus is as dependent on contrast as passive perception and suggest that this effect is attributed to a shared contrast sensitivity early in the visual pathway, before any specialization for motion processing.

Contrast Sensitivity/physiology↗
NASA NTRS2008

Extended Operation Testing of Stirling Convertors in Support of Stirling Radioisotope Power System Development

100 We class Stirling convertors began extended operation testing at NASA Glenn Research Center (GRC) in 2003 with a pair of Technology Demonstration Convertors (TDCs) operating in air. Currently, the number of convertors on extended operation test has grown to 12, including both TDCs and Advanced Stirling Convertors (ASCs) operating both in air and in thermal vacuum. Additional convertors and an electrically heated radioisotope generator will be put on test in the near future. This testing has provided data to support life and reliability estimates and the quality improvements and design changes that have been made to the convertor. The convertors operated 24/7 at the nominal amplitude and power levels. Performance data were recorded on an hourly basis. Techniques to monitor the convertors for change in internal operation included gas analysis, vibration measurements and acoustic emission measurements. This data provided a baseline for future comparison. This paper summarizes the results of over 145,000 hours of TDC testing and 40,000 hours of ASC testing and discusses trends in the data. Data shows the importance of improved materials, hermetic sealing, and quality processes in maintaining convertor performance over long life.

Lewandowski, Edward J.↗
NASA NTRS2009

Extended Operation Testing of Stirling Convertors in Support of Stirling Radioisotope Power System Development

100 We class Stirling convertors began extended operation testing at NASA Glenn Research Center (GRC) in 2003 with a pair of Technology Demonstration Convertors (TDCs) operating in air. Currently, the number of convertors on extended operation test has grown to 12, including both TDCs and Advanced Stirling Convertors (ASCs) operating both in air and in thermal vacuum. Additional convertors and an electrically heated radioisotope generator will be put on test in the near future. This testing has provided data to support life and reliability estimates and the quality improvements and design changes that have been made to the convertor. The convertors operated 24/7 at the nominal amplitude and power levels. Performance data were recorded on an hourly basis. Techniques to monitor the convertors for change in internal operation included gas analysis, vibration measurements, and acoustic emission measurements. This data provided a baseline for future comparison. This paper summarizes the results of over 145,000 hr of TDC testing and 40,000 hr of ASC testing and discusses trends in the data. Data shows the importance of improved materials, hermetic sealing, and quality processes in maintaining convertor performance over long life.

Lewandowski, Edward J.↗
NASA NTRS1978

Long-term CF6 engine performance deterioration: Evaluation of engine S/N 451-479

The performance testing and analytical teardown of CF6-6D engine is summarized. This engine had completed its initial installation on DC-10 aircraft. The investigative test program was conducted inbound prior to normal overhaul/refurbishment. The performance testing included an inbound test, a test following cleaning of the low pressure turbine airfoils, and a final test after leading edge rework and cleaning the stage one fan blades. The analytical teardown consisted of detailed disassembly inspection measurements and airfoil surface finish checks of the as received deteriorated hardware. Included in this report is a detailed analysis of the test cell performance data, a complete analytical teardown report with a detailed description of all observed hardware distress, and an analytical assessment of the performance loss (deterioration) relating measured hardware conditions to losses in both SFC (specific fuel consumption) and EGT (exhaust gas temperature).

Kramer, W. H.↗