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NASA NTRS2000

Tribological Limitations in Gas Turbine Engines: A Workshop to Identify the Challenges and Set Future Directions

The following report represents a compendium of selected speaker presentation materials and observations made by Prof O. Pinkus at the NASA/ASME/Industry sponsored workshop entitled "Tribological Limitations in Gas Turbine Engines" held on September 15-17, 1999 in Albany, New York. The impetus for the workshop came from the ASME's Research Committee on Tribology whose goal is to explore new tribological research topics which may become future research opportunities. Since this subject is of current interest to other industrial and government entities the conference received cosponsorship as noted above. The conference was well attended by government, industrial and academic participants. Topics discussed included current tribological issues in gas turbines as well as the potential impact (drawbacks and advantages) of future tribological technologies especially foil air bearings and magnetic beatings. It is hoped that this workshop report may serve as a starting point for continued discussions and activities in oil-free turbomachinery systems.

DellaCorte, Chris↗
NASA NTRS2000

Hubble Identifies Source of Ultraviolet Light in an Old Galaxy

This videotape is comprised of four segments: (1) a Video zoom in on galaxy M32 using ground images, (2) Hubble images of galaxy M32, (3) Ground base color image of galaxies M31 and M32, and (4) Black and white ground based images of galaxy M32.

Source record↗
NASA NTRS2002

Identifying EGRET Sources

This project was awarded funding from the CGRO program to support ROSAT and ground-based observations of unidentified sources from data obtained by the EGRET instrument on the Compton Gamma-Ray Observatory. The critical items in the project are the individual ROSAT observations that are used to cover the 99% error circle of the unidentified EGRET source. Each error circle is a degree or larger in diameter. Each ROSAT field is about 30 deg in diameter. Hence, a number (>4) of ROSAT pointings must be obtained for each EGRET source to cover the field. The scheduling of ROSAT observations is carried out to maximize the efficiency of the total schedule. As a result, each pointing is broken into one or more sub-pointings of various exposure times. This project was awarded ROSAT observing time for four unidentified EGRET sources, summarized in the table. The column headings are defined as follows: 'Coverings' = number of observations to cover the error circle; 'SubPtg' = total number of sub-pointings to observe all of the coverings; 'Rec'd' = number of individual sub-pointings received to date; 'CompFlds' = number of individual coverings for which the requested complete exposure has been received. Processing of the data can not occur until a complete exposure has been accumulated for each covering.

Schlegel, E.↗
NASA NTRS2002

Seeking and Identifying Phyllosilicates on Mars - A Simulation Study

In a simulation of seeking phyllosilicates on Mars, terrestrial ocean sediments were found to provide high quality Raman spectra of clays with low interfering fluorescence because most organic residues had been converted to graphitic carbon. Additional information is contained in the original extended abstract.

Wang, A.↗
NASA NTRS1998

The Unidentified Infrared Emission Bands: Identified

The so-called Unidentified Infrared or simply UIR bands, the infrared emission band spectrum associated with a wide variety of interstellar objects, can be modeled in detail by laboratory spectra of neutral and positively charged polycyclic aromatic hydrocarbon (PAH) mixtures. Fits are presented for the UIR emission from the protoplanetary nebula IRAS 22272+5435, the diffuse galactic medium, and the Orion HII/photodissociation front - a selection of objects which span the evolutionary range of interstellar material. These data directly address the spectroscopic criticisms previously leveled at the PAH hypothesis and demonstrate that PAH-related molecular species are indeed responsible for this widespread emission. Furthermore, these fits reflect the structure, abundance, and ionization state of the interstellar PAHs and, in turn, provide direct insight into the processes of carbon nucleation, growth and evolution in circumstellar shells and the interstellar medium. To date, no other candidate material which has been proposed to account for the UIR emission can as readily and specifically reproduce these spectral variations. Given the ubiquity of these species, this work demonstrates the tremendous potential of these species as probes of a new and heretofore largely unexplored facet of astrochemistry - potential which should make PAHs the probe of the next millennium much as CO has been for the last quarter century.

Hudgins, Douglas M.↗
NASA NTRS2002

Tribological Limitations in Gas Turbine Engines: A Workshop to Identify the Challenges and Set Future Directions

The following report represents a compendium of selected speaker presentation materials and observations made by Prof. O. Pinkus at the NASA/ASME/Industry sponsored workshop entitled "Tribological Limitations in Gas Turbine Engines" held on September 15-17, 1999 in Albany, New York. The impetus for the workshop came from the ASME's Research Committee on tribology whose goal is to explore new tribological research topics which may become future research opportunities. Since this subject is of current interest to other industrial and government entities the conference received cosponsorship as noted above. The conference was well attended by government, industrial, and academic participants. Topics discussed included current tribological issues in gas turbines as well as the potential impact (drawbacks and advantages) of future tribological technologies especially foil air bearings and magnetic bearings. It is hoped that this workshop report may serve as a starting point for continued discussions and activities in oil-free turbomachinery systems.

DellaCorte, Chris↗
NASA NTRS2001

Iron Charge Distribution as an Identifier of Interplanetary Coronal Mass Ejections

We present solar wind Fe charge state data measured on the Advanced Composition Explorer (ACE) from early 1998 to the middle of 2000. Average Fe charge states in the solar wind are typically around 9 to 11. However, deviations from these average charge states occur, including intervals with a large fraction of Fe(sup greater or = 16+) which are consistently associated with interplanetary coronal mass ejections (ICMEs). By studying the Fe charge state distribution we are able to extract coronal electron temperatures often exceeding 2 x 10(exp 6) kelvins. We also discuss the temporal trends of these events, indicating the more frequent appearance of periods with high Fe charge states as solar activity increases.

Lepri, S. T.↗
NASA NTRS2002

The AstroBiology Explorer (ABE) MIDEX Mission Concept: Identifying Organic Molecules in Space

The Astrobiology Explorer (ABE) is a MIDEX mission concept, currently under Concept Phase A study at NASA's Ames Research Center in collaboration with Ball Aerospace & Technologies, Corp., and managed by NASA's Jet Propulsion Laboratory. ABE will conduct infrared spectroscopic observations to address important problems in astrobiology, astrochemistry, and astrophysics. The core observational program would make fundamental scientific progress in understanding the distribution, identity, and evolution of ices and organic matter in dense molecular clouds, young forming stellar systems, stellar outflows, the general diffuse ISM, HII regions, Solar System bodies, and external galaxies. The ABE instrument concept includes a 0.6 m aperture Ritchey-Chretien telescope and three moderate resolution (R = 2000-3000) spectrometers together covering the 2.5-20 micron spectral region. Large format (1024 x 1024 pixel) IR detector arrays will allow each spectrometer to cover an entire octave of spectral range per exposure without any moving parts. The telescope will be cooled below 50 K by a cryogenic dewar shielded by a sunshade. The detectors will be cooled to approx. 7.5 K by a solid hydrogen cryostat. The optimum orbital configuration for achieving the scientific objectives of the ABE mission is a low background, 1 AU Earth driftaway orbit requiring a Delta II launch vehicle. This configuration provides a low thermal background and allows adequate communications bandwidth and good access to the entire sky over the approx. 1.5 year mission lifetime.

Ennico, Kimberly↗
NASA NTRS2002

The AstroBiology Explorer (ABE) MIDEX Mission: Using Infrared Spectroscopy to Identify Organic Molecules in Space

The AstroBiology Explorer (ABE) mission is one of four selected for Phase A Concept Study in NASA's current call for MIDEX class missions. ABE is a cooled space telescope equipped with spectrographs covering the 2.5-20 micron spectral range. The ABE mission is devoted to the detection and identification of organic and related molecular species in space. ABE is currently under study at NASA's Ames Research Center in collaboration with Ball Aerospace.

Sandford, S. A.↗
NASA NTRS2004

Identifying the Parent Body of the Tagish Lake Meteorite and Characterizing its Internal Heating History and Surface Processes

This short (1-year) funded research encompassed laboratory measurements of the Tagish Lake meteorite samples, experiments of simulated space weathering on them, and comparison with D, T, and P asteroids in reflectance spectrum. In spite of its limited funding and period, we have performed said experiments here at Brown University and at University of Tokyo. Some of the major results were reported at the Lunar and Planetary Science Conference held in Houston in March, 2004. The Tagish Lake meteorite shows a unique visible reflectance spectrum identical to that of the D and T type asteroids. After the present heating experiments at even the lowest temperature of 100 C, the characteristic spectral slope of the Tagish Lake meteorite sample increased. On the other hand, after irradiating its pellet sample with pulse laser, the slope decreased. As the result, the Tagish Lake meteorite and its processed samples have come to cover a wide range of visible reflectance spectra in slope from the C-type asteroids to some extreme T/D-type asteroids, including the P-type asteroids in between. Therefore, logically speaking, our initial affirmation that the Tagish Lake meteorite must have come from one of the D-type asteroids can be wrong if such a meteoritic material is hidden under a space-weathered surface regolith of a C-type asteroid. However, such a case is likely to have a small probability in general. Other major hits of this research includes the first spectral fitting of the P-type asteroids using reflectance spectra derived from the present research. This topic needs more experiments and analysis to be addressed uniquely, and thus further efforts will be proposed.

Hiroi, Takahiro↗
NASA NTRS2004

Identifying Model-Based Reconfiguration Goals through Functional Deficiencies

Model-based diagnosis is now advanced to the point autonomous systems face some uncertain and faulty situations with success. The next step toward more autonomy is to have the system recovering itself after faults occur, a process known as model-based reconfiguration. After faults occur, given a prediction of the nominal behavior of the system and the result of the diagnosis operation, this paper details how to automatically determine the functional deficiencies of the system. These deficiencies are characterized in the case of uncertain state estimates. A methodology is then presented to determine the reconfiguration goals based on the deficiencies. Finally, a recovery process interleaves planning and model predictive control to restore the functionalities in prioritized order.

Benazera, Emmanuel↗
NASA NTRS2004

Identifying Organic Molecules in Space: The AstroBiology Explorer (ABE) Mission Concept

The AstroBiology Explorer (ABE) mission concept consists of a modest dedicated space observatory having a 60 cm class primary mirror cooled to T less than 50 K equipped with medium resolution cross-dispersed spectrometers having cooled large format near- and mid-infrared detector arrays. Such a system would be capable of addressing outstanding problems in Astrochemistry and Astrophysics that are particularly relevant to Astrobiology and addressable via astronomical observation. The mission's observaticxiai program woiild make fundamental scieztific: prngress in establishing the nature, distribution, formation and evolution of organic and other molecular materials in the following extra-terrestrial environments: 1) The Outflow of Dying Stars; 2) The Diffuse Interstellar Medium (DISM); 3) Dense Molecular Clouds, Star Formation Regions, and Young Stellar/Planetary Systems; 4) Planets, Satellites, and Small Bodies within the Solar System; and 5) The Interstellar Media of Other Galaxies ABE could make fundamental progress in all of these area by conducting a 1 to 2 year mission to obtain a coordinated set of infrared spectroscopic observations over the 2.5 - 20 micron spectral range at a spectral resolution of R greater than 2500 of about 1500 galaxies, stars, planetary nebulae, young stellar objects, and solar system objects.

Ennico, Kimberly↗
NASA NTRS2004

Analysis of Adverse Events in Identifying GPS Human Factors Issues

The purpose of this study was to analyze GPS related adverse events such as accidents and incidents (A/I), Aviation Safety Reporting System (ASRS) reports and Pilots Deviations (PDs) to create a framework for developing a human factors risk awareness program. Although the occurrence of directly related GPS accidents is small the frequency of PDs and ASRS reports indicated there is a growing problem with situational awareness in terminal airspace related to different types of GPs operational issues. This paper addresses the findings of the preliminary research and a brief discussion of some of the literature on related GPS and automation issues.

Adams, Catherine A.↗
NASA NTRS2002

Identifying head-trunk and lower limb contributions to gaze stabilization during locomotion

The goal of the present study was to determine how the multiple, interdependent full-body sensorimotor subsystems respond to a change in gaze stabilization task constraints during locomotion. Nine subjects performed two gaze stabilization tasks while walking at 6.4 km/hr on a motorized treadmill: 1) focusing on a central point target; 2) reading numeral characters; both presented at 2 m in front at the level of their eyes. While subjects performed the tasks we measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, tibia and foot, accelerations along the vertical axis at the head and the tibia, and the vertical forces acting on the support surface. We tested the hypothesis that with the increased demands placed on visual acuity during the number recognition task, subjects would modify full-body segmental kinematics in order to reduce perturbations to the head in order to successfully perform the task. We found that while reading numeral characters as compared to the central point target: 1) compensatory head pitch movement was on average 22% greater despite the fact that the trunk pitch and trunk vertical translation movement control were not significantly changed; 2) coordination patterns between head and trunk as reflected by the peak cross correlation between the head pitch and trunk pitch motion as well as the peak cross correlation between the head pitch and vertical trunk translation motion were not significantly changed; 3) knee joint total movement was on average 11% greater during the period from the heel strike event to the peak knee flexion event in stance phase of the gait cycle; 4) peak acceleration measured at the head was significantly reduced by an average of 13% in four of the six subjects. This was so even when the peak acceleration at the tibia and the transmission of the shock wave at heel strike (measured by the peak acceleration ratio of the head/tibia and the time lag between the tibial and head peak accelerations) remained unchanged. Taken together these results provide further evidence that the full body contributes to gaze stabilization during locomotion, and that its different functional elements can be modified online to contribute to gaze stabilization for different visual task constraints.

NASA Center JSC↗
NASA NTRS2002

Microarray analysis identifies Salmonella genes belonging to the low-shear modeled microgravity regulon

The low-shear environment of optimized rotation suspension culture allows both eukaryotic and prokaryotic cells to assume physiologically relevant phenotypes that have led to significant advances in fundamental investigations of medical and biological importance. This culture environment has also been used to model microgravity for ground-based studies regarding the impact of space flight on eukaryotic and prokaryotic physiology. We have previously demonstrated that low-shear modeled microgravity (LSMMG) under optimized rotation suspension culture is a novel environmental signal that regulates the virulence, stress resistance, and protein expression levels of Salmonella enterica serovar Typhimurium. However, the mechanisms used by the cells of any species, including Salmonella, to sense and respond to LSMMG and identities of the genes involved are unknown. In this study, we used DNA microarrays to elucidate the global transcriptional response of Salmonella to LSMMG. When compared with identical growth conditions under normal gravity (1 x g), LSMMG differentially regulated the expression of 163 genes distributed throughout the chromosome, representing functionally diverse groups including transcriptional regulators, virulence factors, lipopolysaccharide biosynthetic enzymes, iron-utilization enzymes, and proteins of unknown function. Many of the LSMMG-regulated genes were organized in clusters or operons. The microarray results were further validated by RT-PCR and phenotypic analyses, and they indicate that the ferric uptake regulator is involved in the LSMMG response. The results provide important insight about the Salmonella LSMMG response and could provide clues for the functioning of known Salmonella virulence systems or the identification of uncharacterized bacterial virulence strategies.

Non-NASA Center↗
NASA NTRS1996

Identifying yield-optimizing environments for two cowpea breeding lines by manipulating photoperiod and harvest scenario

Photoperiod and harvest scenario of cowpea (Vigna unguiculata L. Walp) canopies were manipulated to optimize productivity for use in future controlled ecological life-support systems. Productivity was measured by edible yield rate (EYR:g m-2 day-1), shoot harvest index (SHI: g edible biomass [g total shoot dry weight]), and yield-efficiency rate (YER:g edible biomass m-2 day-1 per[g nonedible shoot dry weight]). Breeding lines 'IT84S-2246' (S-2246) and "IT82D-889' (D-889) were grown in a greenhouse under 8-, 12-, or 24-h photoperiods. S-2246 was short-day and D-889 was day-neutral for flowering. Under each photoperiod, cowpeas were harvested either for leaves only, seeds only, or leaves plus seeds (mixed harvest). Photoperiod did not affect EYR of either breeding line for any harvest scenario tested. Averaged over both breeding lines, seed harvest gave the highest EYR at 6.7 g m-2 day-1. The highest SHI (65%) and YER (94 mg m-2 day-1 g-1) were achieved for leaf-only harvest of D-889 under an 8-h photoperiod. For leaf-only harvest of S-2246, both SHI and YER increased with increasing photoperiod, but declined for seed-only and mixed harvests. However, photoperiod had no effect on SHI or YER for D-889 for any harvest scenario. A second experiment utilized the short-day cowpea breeding line 'IT89KD-288' (D-288) and the day-neutral breeding line 'IT87D-941-1' (D-941) to compare yield parameters using photoperiod extension under differing lamp types. This experiment confirmed the photoperiod responses of D-889 and S-2246 to a mixed-harvest scenario and indicated that daylength extension with higher irradiance from high pressure sodium lamps further suppressed EYR, SHI, and YER of the short-day breeding line D-288.

Non-NASA Center↗