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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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NASA NTRS2004

Analysis of RXTE data on Clusters of Galaxies

This grant provided support for the reduction, analysis and interpretation of of hard X-ray (HXR, for short) observations of the cluster of galaxies RXJO658--5557 scheduled for the week of August 23, 2002 under the RXTE Cycle 7 program (PI Vahe Petrosian, Obs. ID 70165). The goal of the observation was to search for and characterize the shape of the HXR component beyond the well established thermal soft X-ray (SXR) component. Such hard components have been detected in several nearby clusters. distant cluster would provide information on the characteristics of this radiation at a different epoch in the evolution of the imiverse and shed light on its origin. We (Petrosian, 2001) have argued that thermal bremsstrahlung, as proposed earlier, cannot be the mechanism for the production of the HXRs and that the most likely mechanism is Compton upscattering of the cosmic microwave radiation by relativistic electrons which are known to be present in the clusters and be responsible for the observed radio emission. Based on this picture we estimated that this cluster, in spite of its relatively large distance, will have HXR signal comparable to the other nearby ones. The planned observation of a relatively The proposed RXTE observations were carried out and the data have been analyzed. We detect a hard X-ray tail in the spectrum of this cluster with a flux very nearly equal to our predicted value. This has strengthen the case for the Compton scattering model. We intend the data obtained via this observation to be a part of a larger data set. We have identified other clusters of galaxies (in archival RXTE and other instrument data sets) with sufficiently high quality data where we can search for and measure (or at least put meaningful limits) on the strength of the hard component. With these studies we expect to clarify the mechanism for acceleration of particles in the intercluster medium and provide guidance for future observations of this intriguing phenomenon by instrument on GLAST. The details of the nonthermal particle population has important implications for the theories of cluster formation, mergers and evolution. The results of this work were first presented at the High Energy Division meeting of the American astronomical Society at Mt. Tremblene, Canada (Petrosian et al. 2003). and in an invited review talk at the General Assembly of the International Astronomical Union at Sydney, Australia (Petrosian, 2003). A paper describe the observations, the data analysis and its implication is being prepared for publication in the Astrophysical Journal.

Petrosian, Vahe↗
NASA NTRS2004

The IGS Global Data Center at the CDDIS: An Update

The Crustal Dynamics Data Information System (CDDIS) has served as a global data center for the International GPS Service (IGS) since its start in June 1992, providing on-line access to data from nearly 300 sites on a daily basis. The CDDIS provides easy and ready access to a variety of data sets, products, and information about these data. The specialized nature of the CDDIS lends itself well to enhancement and thus can accommodate diverse data sets and user requirements. This poster paper will present information about the GPS and GLONASS data and products archive at the CDDIS. General information about the system, the computer architecture, archive contents, and future plans, and its support of other international space geodesy services (the ILRS, IVS, and IDS) will be discussed.

Noll, Carey↗
NASA NTRS2004

Automated Classification of ROSAT Sources Using Heterogeneous Multiwavelength Source Catalogs

We describe an on-line system for automated classification of X-ray sources, ClassX, and present preliminary results of classification of the three major catalogs of ROSAT sources, RASS BSC, RASS FSC, and WGACAT, into six class categories: stars, white dwarfs, X-ray binaries, galaxies, AGNs, and clusters of galaxies. ClassX is based on a machine learning technology. It represents a system of classifiers, each classifier consisting of a considerable number of oblique decision trees. These trees are built as the classifier is 'trained' to recognize various classes of objects using a training sample of sources of known object types. Each source is characterized by a preselected set of parameters, or attributes; the same set is then used as the classifier conducts classification of sources of unknown identity. The ClassX pipeline features an automatic search for X-ray source counterparts among heterogeneous data sets in on-line data archives using Virtual Observatory protocols; it retrieves from those archives all the attributes required by the selected classifier and inputs them to the classifier. The user input to ClassX is typically a file with target coordinates, optionally complemented with target IDs. The output contains the class name, attributes, and class probabilities for all classified targets. We discuss ways to characterize and assess the classifier quality and performance and present the respective validation procedures. Based on both internal and external validation, we conclude that the ClassX classifiers yield reasonable and reliable classifications for ROSAT sources and have the potential to broaden class representation significantly for rare object types.

McGlynn, Thomas↗
NASA NTRS2003

Regulatory coding of lymphoid lineage choice by hematopoietic transcription factors

During lymphopoiesis, precursor cells negotiate a complex regulatory space, defined by the levels of several competing and cross-regulating transcription factors, before arriving at stable states of commitment to the B-, T- and NK-specific developmental programs. Recent perturbation experiments provide evidence that this space has three major axes, corresponding to the PU.1 versus GATA-1 balance, the intensity of Notch signaling through the CSL pathway, and the ratio of E-box transcription factors to their Id protein antagonists.

Non-NASA Center↗
NASA NTRS2004

Advanced Materials and Coatings for Aerospace Applications

In the application area of aerospace tribology, researchers and developers must guarantee the highest degree of reliability for materials, components, and systems. Even a small tribological failure can lead to catastrophic results. The absence of the required knowledge of tribology, as Professor H.P. Jost has said, can act as a severe brake in aerospace vehicle systems-and indeed has already done so. Materials and coatings must be able to withstand the aerospace environments that they encounter, such as vacuum terrestrial, ascent, and descent environments; be resistant to the degrading effects of air, water vapor, sand, foreign substances, and radiation during a lengthy service; be able to withstand the loads, stresses, and temperatures encountered form acceleration and vibration during operation; and be able to support reliable tribological operations in harsh environments throughout the mission of the vehicle. This presentation id divided into two sections: surface properties and technology practice related to aerospace tribology. The first section is concerned with the fundamental properties of the surfaces of solid-film lubricants and related materials and coatings, including carbon nanotubes. The second is devoted to applications. Case studies are used to review some aspects of real problems related to aerospace systems to help engineers and scientists to understand the tribological issues and failures. The nature of each problem is analyzed, and the tribological properties are examined. All the fundamental studies and case studies were conducted at the NASA Glenn Research Center.

Miyoshi, Kazuhisa↗
NASA NTRS2004

NASA GEOS-3/TRMM Re-analysis: Capturing Observed Tropical Rainfall Variability in Global Analysis for Climate Research

Understanding climate variability over a wide range of space-time scales requires a comprehensive description of the earth system. Global analyses produced by a fixed assimilation system (i.e., re-analyses) - as their quality continues to improve - have the potential of providing a vital tool for meeting this challenge. But at the present time, the usefulness of re-analyses is limited by uncertainties in such basic fields as clouds, precipitation, and evaporation - especially in the tropics, where observations are relatively sparse. Analyses of the tropics have long been shown to be sensitive to. the treatment of cloud precipitation processes, which remains a major source of uncertainty in current models. Yet, for many climate studies it is crucial that analyses can accurately reproduce the observed rainfall intensity and variability since a small error of 1 mm/d in surface rain translates into an error of approx. 30 W/sq m in energy (latent heat) flux. Currently, discrepancies between the observed and analyzed monthly-mean rain rates averaged to 100 km x 100 km resolution can exceed 4 mm/d (or 120 W/sq m ), compared to uncertainties in surface radiative fluxes of approx. 10-20 W/sq m . Improving precipitation in analyses would reduce a major source of uncertainty in the global energy budget. Uncertainties in tropical precipitation have also been a major impediment in understanding how the tropics interact with other regions, including the remote response to El Nino/Southern Oscillation (ENSO) variability on interannual time scales, the influence of Madden-Julian Oscillation (MJO) and monsoons on intraseasonal time scales. A global analysis that can replicate the observed precipitation variability together with physically consistent estimates of other atmospheric variables provides the key to breaking this roadblock. NASA Goddard Space Flight Center has been exploring the use of satellite-based microwave rainfall measurements in improving global analyses and has recently produced a multi-year, 1 x 1 TRMM re-analysis , which assimilates 6-hourly TMI and SSM/I surface rain rates over tropical oceans using a ID variational continuous assimilation (VCA) procedure in the GEOS-3 global data assimilation system. The analysis period extends from 1 November 1997 through 3 1 December 2002. The goal is to produce a multi-year global analysis that is dynamically consistent with available tropical precipitation observations for the community to assess its utility in climate applications and identify areas for further improvements. A distinct feature of the GEOS-3RRMh4 re-analysis is that its precipitation analysis is not derived from a short-term forecast (as done in most operational systems) but is given by a time- continuous model integration constrained by precipitation observations within a 6-h analysis window, while the wind, temperature, and pressure fields are allowed to directly respond to the improved precipitation and associated latent heating structures within the same analysis window. In this talk, I will assess the impact VCA precipitation assimilation on analyses of climate signals ranging from a few weeks to interannual time scales and compare results against other operational and reanalysis products.

Hou, Arthur Y.↗
NASA NTRS2004

The Application of Probabilistic Methods to the Mistuning Problem

FMM is a reduced order model for efficiently calculating the forced response of a mistuned bladed disk. FMM ID is a companion program which determines the mistuning in a particular rotor. Together, these methods provide a way to acquire data on the mistuning in a population of bladed disks, and then simulate the forced response of the fleet. This process is tested experimentally, and the simulated results are compared with laboratory measurements of a fleet of test rotors. The method is shown to work quite well. It is found that accuracy of the results depends on two factors: the quality of the statistical model used to characterize mistuning, and how sensitive the system is to errors in the statistical modeling.

Griffin, J. H.↗
NASA NTRS2005

Morphological Evolution of Directional Solidification Interfaces in Microgravity: An Analysis of Model Experiments Performed on the International Space Station

A series of experiments performed using the Pore Formation and Mobility Investigation (PFMI) apparatus within the glovebox facility (GBX) on board the International Space Station (ISS) has provided video images of the morphological evolution of a three-dimensional interface in a diffusion controlled regime. The experimental samples were prepared on ground by filling glass tubes, 1 cm ID and approximately 30 cm in length, with "alloys" of succinonitrile (SCN) and water in an atmosphere of nitrogen at 450 millibar pressure. The compositions of the samples processed and analyzed are 0.25,0.5 and 1.0 wt% water. Experimental processing parameters of temperature gradient and translation speed, as well as camera settings, were remotely monitored and manipulated from the ground Telescience Center (TSC) at the Marshall !3pace Flight Center. During the experiments, the sample was first subjected to a unidirectional melt back, generally at 10 microns per second, with a constant temperature gradient ahead of the melting interface. Following the melt back, the interface was allowed to stabilize before translation is initiated. The temperatures in the sample were monitored by six in situ thermocouples and the position is monitored by an optical linear encoder. For the experiments performed and analyzed, the gradients ranged from 2.5 - 3.3 K/mm and the initial pulling velocities ranged from 0.7 micron per second to 1 micron per second with subsequent transition velocities of up to 100 microns per second. The data provided by the PFMI for analysis includes near-real-time (NRT) video captured on the ground during the experiment runs, ISS Video Tape Recorder (VTR) data dumped from the VTR at the end of the experiment run and recorded on the ground, telemetry data including temperature and position measurements, and limited flight HI-8 tapes in 2 camera views of experiment runs for which tapes have been returned to the investigators from ISS. Because of limited down mass from the ISS, the majority of the initial analysis has been performed using the NRT and VTR video data but will be supplemented with the HI-8 video as it becomes available. hardware and procedures required to prepare samples for correlation to flight samples is described. Using this ground-based system, a series of experiments have been performed for direct comparison with the flight data. The results of these comparisons as well as implications to future microgravity experiments are presented and discussed. A ground-based thin-sample directional solidification system as well as all associated

Strutzenberg, Louise L.↗
NASA NTRS2005

Observation of an Aligned Gas - Solid "Eutectic" during Controlled Directional Solidification Aboard the International Space Station - Comparison with Ground-based Studies

Direct observation of the controlled melting and solidification of succinonitrile was conducted in the glovebox facility of the International Space Station (ISS). The experimental samples were prepared on ground by filling glass tubes, 1 cm ID and approximately 30 cm in length, with pure succinonitrile (SCN) in an atmosphere of nitrogen at 450 millibar pressure for eventual processing in the Pore Formation and Mobility Investigation (PFMI) apparatus in the glovebox facility (GBX) on board the ISS. Real time visualization during controlled directional melt back of the sample showed nitrogen bubbles emerging from the interface and moving through the liquid up the imposed temperature gradient. Over a period of time these bubbles disappear by dissolving into the melt. Translation is stopped after melting back of about 9 cm of the sample, with an equilibrium solid-liquid interface established. During controlled re-solidification, aligned tubes of gas were seen growing perpendicular to the planar solid/liquid interface, inferring that the nitrogen previously dissolved into the liquid SCN was now coming out at the solid/liquid interface and forming the little studied liquid = solid + gas eutectic-type reaction. The observed structure is evaluated in terms of spacing dimensions, interface undercooling, and mechanisms for spacing adjustments. Finally, the significance of processing in a microgravity environment is ascertained in view of ground-based results.

Grugel, R. N.↗
NASA NTRS2004

Archiving Space Geodesy Data for 20+ Years at the CDDIS

Since 1982, the Crustal Dynamics Data Information System (CDDIS) has supported the archive and distribution of geodetic data products acquired by NASA programs. These data include GPS (Global Positioning System), GLONASS (GLObal NAvigation Satellite System), SLR (Satellite Laser Ranging), VLBI (Very Long Baseline Interferometry), and DORIS (Doppler Orbitography and Radiolocation Integrated by Satellite). The data archive supports NASA's space geodesy activities through the Solid Earth and Natural Hazards (SENH) program. The CDDIS data system and its archive have become increasingly important to many national and international programs, particularly several of the operational services within the International Association of Geodesy (IAG), including the International GPS Service (IGS), the International Laser Ranging Service (ILRS), the International VLBI Service for Geodesy and Astrometry (IVS), the International DORIS Service (IDS), and the International Earth Rotation Service (IERS). The CDDIS provides easy and ready access to a variety of data sets, products, and information about these data. The specialized nature of the CDDIS lends itself well to enhancement and thus can accommodate diverse data sets and user requirements. All data sets and metadata extracted from these data sets are accessible to scientists through ftp and the web; general information about each data set is accessible via the web. The CDDIS, including background information about the system and its user communities, the computer architecture, archive contents, available metadata, and future plans will be discussed.

Noll, Carey E.↗
NASA NTRS2004

Security Management and Safeguards Office

The Security Management and Safeguards Office at NASA is here to keep the people working in a safe environment. They also are here to protect the buildings and documents from sabotage, espionage, and theft. During the summer of 2004, I worked with Richard Soppet in Physical Security. While I was working here I helped out with updating the map that we currently use at NASA Glenn Research Center, attended meetings for homeland security, worked with the security guards and the locksmith. The meetings that I attended for homeland security talked about how to protect ourselves before something happened, they told us to always be on the guard and look for anything suspicious, and the different ways that terrorist groups operate. When I was with the security guards I was taught how to check someone into the base, showed how to use a radar gun, observed a security guard make a traffic stop for training and was with them while they patrolled NASA Glenn Research Center to make sure things were running smooth and no one was in danger. When I was with the lock smith I was taught how to make keys and locks for the employees here at NASA. The lock smith also showed me that he had inventory cabinets of files that show how many keys were out to people and who currently has access to the rooms that they keys were made for. I also helped out the open house at NASA Glenn Research Center. I helped out by showing the Army Reserves, and Brook Park's SWAT team where all the main events were going to take place a week before the open house was going to begin. Then during the open house I helped out by making sure people had there IDS, checked through there bags, and handed out a map to them that showed where the different activities were going to take place. So the main job here at NASA Glenn Research Center for the Security Management and Safeguards Office is to make sure that nothing is stolen, sabotaged, and espionaged. Also most importantly make sure all the employees here at NASA are in a safe environment.

Bewley, Nathaniel M.↗
NASA NTRS2005

Technologies on the Horizon for Product Identification

Contents include the following: Configuration management. Component/system to report. Unique item identifier (UID). Aftemarket undocumented configuration change. Revolutionary new brake system. Traceability of critical parts. Automatic identification used at many levels. Product ID problems that inhibited traceability. Direct part marking enables life cycle tracking.

Schramm, Harry Fred, Jr.↗
NASA NTRS2003

Fabrication And Evaluation Of Sic/Sic Tubes With Various Fiber Architectures

SiC/SiC composites are excellent material candidates for high temperature applications where the performance requirements are high strength, high creep-rupture resistance, high environmental durability, and high thermal conductivity. In the past, the NASA UEET program has demonstrated fabrication of high-performance SiC/SiC flat panels reinforced by Sylramic-iBN SiC fibers. Currently NASA UEET is scaling up this SiC/SiC system by fabrication of more complex shaped components using the same fiber type. This paper reports the effects of various fiber architectures on the processing, mechanical, and durability behavior of small-diameter 0.5" ID SiC/SiC tubes, which are potential sub-elements for leading edges and cooling channels in turbine vanes and blades. Nine different fiber architectures were utilized for construction of seamless tube preforms, from simple 2D jelly-rolling to complex braiding, pin-weaving, filament-winding and 3D orthogonal weaving with approximately 5% fibers in the thru-thickness direction. Using the BN interphase and Sic matrix processing steps established for the flat panels, SiC/SiC tubes were fabricated with wall thicknesses of approximately 60 mils and total fiber fractions of approximately 35%. The "D" split ring tests for hoop tensile properties, micro-structural examinations for relationship between fiber architecture formation and matrix infiltration, and the low-pressure burner rig tests for the high temperature durability under thru-thickness thermal gradient were conducted. The better matrix infiltration and higher hoop strength were achieved using the tri-axial braided and the three-float pin woven SiC/SiC tubes. In general, it needs not only higher hoop direction fibers but also axial direction fibers for the higher hoop strength and the better infiltration, respectively. These results are analyzed to offer general guidelines for selecting fiber pre-form architectures and SiC/SiC processes that maximize tube hoop strength, thru-thickness thermal conductivity, and burner-rig durability under a high thermal gradient.

Yun, H. M.↗
NASA NTRS2005

NASA SpaceWire Status

Three projects are developing SpaceWire upper layer protocols: JWST, LRO, GOES-R. JWST protocol development was complete before Protocol ID field was introduced to the standard. Commanding is done by using CCD5 packets tunneled through SpaceWire. Science Data packet is optimized for implementation specific requirements. Lunar Reconnaissance Orbiter (LRD) investigated using the SnP Rmap protocol but chose to use CCSDS tunneled through SpaceWire. GOES-R is using CCDS tunneled through SpaceWire with project developed Reliable Delivery protocol. Reliable Delivery protocol may be used to replace MIL-STD-1553 for other mission. CCDS is the native format for the software bus for many NASA GSFC missions and therefore it is a natural packet format to tunnel through SpaceWire.

Rakow, Glenn Parker↗
NASA NTRS2005

Courant Number and Mach Number Insensitive CE/SE Euler Solvers

It has been known that the space-time CE/SE method can be used to obtain ID, 2D, and 3D steady and unsteady flow solutions with Mach numbers ranging from 0.0028 to 10. However, it is also known that a CE/SE solution may become overly dissipative when the Mach number is very small. As an initial attempt to remedy this weakness, new 1D Courant number and Mach number insensitive CE/SE Euler solvers are developed using several key concepts underlying the recent successful development of Courant number insensitive CE/SE schemes. Numerical results indicate that the new solvers are capable of resolving crisply a contact discontinuity embedded in a flow with the maximum Mach number = 0.01.

Chang, Sin-Chung↗
NASA NTRS2005

Fundamental Mistuning Model for Probabilistic Analysis Studied Experimentally

The Fundamental Mistuning Model (FMM) is a reduced-order model for efficiently calculating the forced response of a mistuned bladed disk. FMM ID is a companion program that determines the mistuning in a particular rotor. Together, these methods provide a way to acquire mistuning data in a population of bladed disks and then simulate the forced response of the fleet. This process was tested experimentally at the NASA Glenn Research Center, and the simulated results were compared with laboratory measurements of a "fleet" of test rotors. The method was shown to work quite well. It was found that the accuracy of the results depends on two factors: (1) the quality of the statistical model used to characterize mistuning and (2) how sensitive the system is to errors in the statistical modeling.

Griffin, Jerry H.↗
NASA NTRS2005

Implementation of Real-Time Feedback Flow Control Algorithms on a Canonical Testbed

This report summarizes the activities on "Implementation of Real-Time Feedback Flow Control Algorithms on a Canonical Testbed." The work summarized consists primarily of two parts. The first part summarizes our previous work and the extensions to adaptive ID and control algorithms. The second part concentrates on the validation of adaptive algorithms by applying them to a vibration beam test bed. Extensions to flow control problems are discussed.

Tian, Ye↗