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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Improvement of TOPEX/POSEIDON and Jason-1 Geophysical Data Record for Global Change Studies and Coastal Applications

The Earth's modem climate change has been characterized by interlinked changes in temperature, CO2, ice sheets and sea level. Global sea level change is a critical indicator for study of contemporary climate change. Sea level rise appears to have accelerated since the ice sheet retreats have stopped some 5000 years ago and it is estimated that the sea level rise has been approx. 15 cm over the last century. Contemporary radar altimeters represent the only technique capable of monitoring global sea level change with accuracy approaching 1 mm/yr and with a temporal scale of days and a spatial scale of 100 km or longer. This report highlights the major accomplishments of the TOPEX/POSEIDON (T/P) Extended Mission and Jason-1 science investigation. The primary objectives of the investigation include the calibration and improvement of T/P and Jason-1 altimeter data for global sea level change and coastal tide and circulation studies. The scientific objectives of the investigation include: (1) the calibration and improvement of T/P and Jason-1 data as a reference measurement system for the accurate cross-linking with other altimeter systems (Seasat, Geosat, ERS-1, ERS-2, GFO-1, and Envisat), (2) the improved determination and the associated uncertainties of the long-term (15-year) global mean sea level change using multiple altimeters, (3) the characterization of the sea level change by analyses of independent data, including tide gauges, sea surface temperature, and (4) the improvement coastal radar altimetry for studies including coastal ocean tide modeling and coastal circulation. Major accomplishments of the investigation include the development of techniques for low-cost radar altimeter absolute calibration (including the associated GPS-buoy technology), coastal ocean tide modeling, and the linking of multiple altimeter systems and the resulting determination of the 15-year (1985-1999) global mean sea level variations. The current rate of 15-year sea level rise observed by multiple satellite altimetry is +2.3 +/- 1.2 mm/yr, which is in general agreement with the analysis of sparsely distributed tide gauge measurements for the same data span, and represents the first such determination of sea level change in its kind.

Shum, C. K.↗
NASA NTRS2004

Application of Thermo-Mechanical Measurements of Plastic Packages for Reliability Evaluation of PEMS

Thermo-mechanical analysis (TMA) is typically employed for measurements of the glass transition temperature (Tg) and coefficients of thermal expansion (CTE) in molding compounds used in plastic encapsulated microcircuits (PEMs). Application of TMA measurements directly to PEMs allows anomalies to be revealed in deformation of packages with temperature, and thus indicates possible reliability concerns related to thermo-mechanical integrity and stability of the devices. In this work, temperature dependencies of package deformation were measured in several types of PEMs that failed environmental stress testing including temperature cycling, highly accelerated stress testing (HAST) in humid environments, and bum-in (BI) testing. Comparison of thermo-mechanical characteristics of packages and molding compounds in the failed parts allowed for explanation of the observed failures. The results indicate that TMA of plastic packages might be used for quality evaluation of PEMs intended for high-reliability applications.

Sharma, Ashok K.↗
NASA NTRS2001

The g-LIMIT Microgravity Vibration Isolation System for the Microgravity Science Glovebox

For many microgravity science experiments in the International Space Station, the ambient acceleration environment will be exceed desirable levels. To provide a more quiescent acceleration environment to the microgravity payloads, a vibration isolation system named g-LIMIT (GLovebox Integrated Microgravity Isolation Technology) is being designed. g-LIMIT is a sub-rack level isolation system for the Microgravity Science Glovebox that can be tailored to a variety of applications. Scheduled for launch on the UF-1 mission, the initial implementation of g-LIMIT will be a Characterization Test in the Microgravity Science Glovebox. g-LIMIT will be available to glovebox investigators immediately after characterization testing. Standard MSG structural and umbilical interfaces will be used so that the interface requirements are minimized. g-LIMIT consists of three integrated isolator modules, each of which is comprised of a dual axis actuator, two axes of acceleration sensing, two axes of position sensing, control electronics, and data transmission capabilities in a small-volume package. In addition, this system provides the unique capability for measuring quasi-steady acceleration of the experiment independent of accelerometers as a by-product of the control system and will have the capability of generating user-specified pristine accelerations to enhance experiment operations.

Whorton, Mark S.↗
NASA NTRS1986

Advanced natural laminar flow airfoil with high lift to drag ratio

An experimental verification of a high performance natural laminar flow (NLF) airfoil for low speed and high Reynolds number applications was completed in the Langley Low Turbulence Pressure Tunnel (LTPT). Theoretical development allowed for the achievement of 0.70 chord laminar flow on both surfaces by the use of accelerated flow as long as tunnel turbulence did not cause upstream movement of transition with increasing chord Reynolds number. With such a rearward pressure recovery, a concave type deceleration was implemented. Two-dimensional theoretical analysis indicated that a minimum profile drag coefficient of 0.0026 was possible with the desired laminar flow at the design condition. With the three-foot chord two-dimensional model constructed for the LTPT experiment, a minimum profile drag coefficient of 0.0027 was measured at c sub l = 0.41 and Re sub c = 10 x 10 to the 6th power. The low drag bucket was shifted over a considerably large c sub l range by the use of the 12.5 percent chord trailing edge flap. A two-dimensional lift to drag ratio (L/D) was 245. Surprisingly high c sub l max values were obtained for an airfoil of this type. A 0.20 chort split flap with 60 deg deflection was also implemented to verify the airfoil's lift capabilities. A maximum lift coefficient of 2.70 was attained at Reynolds numbers of 3 and 6 million.

Viken, Jeffrey K.↗
NASA NTRS1988

A Navier-Stokes solver for cascade flows

A computer code for solving the Reynolds averaged full Navier-Stokes equations has been developed and applied using sheared H-type grids. The Baldwin-Lomax eddy-viscosity model is used for turbulence closure. The integration in time is based on an explicit four-stage Runge-Kutta scheme. Local time stepping, variable coefficient implicit residual smoothing, and a full multigrid method have been implemented to accelerate steady state calculations. Comparisons with experimental data show that the code is an accurate viscous solver and can give very good blade-to-blade predictions for engineering applications in less than 100 multigrid cycles on the finest mesh.

Arnone, A.↗
NASA NTRS1989

Rarefied-flow aerodynamics measurement experiment on the aeroassist flight experiment

The rarefied-flow aerodynamics measurement experiment, which is expected to measure the rarefied-flow flight regime with an accelerometer on the aeroassist flight experiment, is discussed. The experiment concept and mission plans are examined and the experiment configuration is illustrated. The experiment plans include flight measurements of aerodynamic force and moment coefficients throughout the rarefied regime to verify ground-to-flight extrapolation techniques. In addition, the experiment includes the study of acceleration rates and the effects of attitude variation. The experiment is also expected to evaluate the determination of vehicle mass properties to study robust control theory formulations which are applicable to special return aeroassisted orbital transfer vehicle payloads.

Blanchard, R. C.↗
NASA NTRS1993

Green's function methods in heavy ion shielding

An analytic solution to the heavy ion transport in terms of Green's function is used to generate a highly efficient computer code for space applications. The efficiency of the computer code is accomplished by a nonperturbative technique extending Green's function over the solution domain. The computer code can also be applied to accelerator boundary conditions to allow code validation in laboratory experiments.

Wilson, John W.↗
NASA NTRS1993

Low-frequency vibration environment for five Shuttle missions

The Microgravity Science and Applications Division's (MSAD) program to record and analyze the Shuttle's vibration environment is reviewed. This program provides microgravity science investigators with time and frequency analyses of the acceleration environment during their experiments' operation. Information is also provided for future investigators on the expected Shuttle vibration environment. As background, the two major elements of the program are discussed, the Space Acceleration Measurement System (SAMS) and the Acceleration Characterization and Analysis Project (ACAP). A comparison of the acceleration measurements from five Shuttle missions is discussed.

Baugher, George R.↗
NASA NTRS1993

Shielding from space radiations

This Progress Report covering the period of December 1, 1992 to June 1, 1993 presents the development of an analytical solution to the heavy ion transport equation in terms of Green's function formalism. The mathematical development results are recasted into a highly efficient computer code for space applications. The efficiency of this algorithm is accomplished by a nonperturbative technique of extending the Green's function over the solution domain. The code may also be applied to accelerator boundary conditions to allow code validation in laboratory experiments. Results from the isotopic version of the code with 59 isotopes present for a single layer target material, for the case of an iron beam projectile at 600 MeV/nucleon in water is presented. A listing of the single layer isotopic version of the code is included.

Chang, C. Ken↗
NASA NTRS1993

Shielding from space radiations

This Progress Report covering the period of 1 June 1993 to 1 Dec. 1993 presents the development of an analytical solution to the heavy ion transport equation in terms of a one-layer Green's function formalism. The mathematical developments are recasted into an efficient computer code for space applications. The efficiency of this algorithm is accomplished by a nonperturbative technique of extending the Green's function over the solution domain. The code may also be applied to accelerator boundary conditions to allow code validation in laboratory experiments. Results from the isotopic version of the code with 80 isotopes present for a single layer target material, for the case of an Iron beam projectile at 600 MeV/nucleon in water is presented.

Chang, C. Ken↗
NASA NTRS1993

Shielding from space radiations

This Progress Report covering the period of 1 June 1993 to 1 Dec. 1993 presents the development of an analytical solution to the heavy ion transport equation in terms of a one-layer Green's function formalism. The mathematical developments are recasted into an efficient computer code for space applications. The efficiency of this algorithm is accomplished by a nonperturbative technique of extending the Green's function over the solution domain. The code may also be applied to accelerator boundary conditions to allow code validation in laboratory experiments. Results from the isotopic version of the code with 80 isotopes present for a single layer target material, for the case of an iron beam projectile at 600 MeV/nucleon in water is presented.

Chang, C. Ken↗
NASA NTRS1993

Leading-Edge Votex-System Details Obtained on F-106B Aircraft Using a Rotating Vapor Screen and Surface Techniques

A flight research program to study the flow structure and separated-flow origins over an F-106B aircraft wing is described. The flight parameters presented include Mach numbers from 0.26 to 0.81, angles of attack from 8.5 deg to 22.5 deg, Reynolds numbers from 22.6 x 10(exp 6) to 57.3 x 10(exp 6) and load factors from 0.9 to 3.9 times the acceleration due to gravity. Techniques for vapor screens, image enhancement, photogrammetry, and computer graphics are integrated to analyze vortex-flow systems. Emphasis is placed on the development and application of the techniques. The spatial location of vortex cores and their tracks over the wing are derived from the analysis. Multiple vortices are observed and are likely attributed to small surface distortions in the wing leading-edge region. A major thrust is to correlate locations of reattachment lines obtained from the off-surface (vapor-screen) observations with those obtained from on-surface oil-flow patterns and pressure-port data. Applying vapor-screen image data to approximate reattachment lines is experimental, but depending on the angle of attack, the agreement with oil-flow results is generally good. Although surface pressure-port data are limited, the vapor-screen data indicate reattachment point occurrences consistent with the available data.

Lamar, John E.↗
NASA NTRS1994

Parallel Computational Fluid Dynamics: Current Status and Future Requirements

One or the key objectives of the Applied Research Branch in the Numerical Aerodynamic Simulation (NAS) Systems Division at NASA Allies Research Center is the accelerated introduction of highly parallel machines into a full operational environment. In this report we discuss the performance results obtained from the implementation of some computational fluid dynamics (CFD) applications on the Connection Machine CM-2 and the Intel iPSC/860. We summarize some of the experiences made so far with the parallel testbed machines at the NAS Applied Research Branch. Then we discuss the long term computational requirements for accomplishing some of the grand challenge problems in computational aerosciences. We argue that only massively parallel machines will be able to meet these grand challenge requirements, and we outline the computer science and algorithm research challenges ahead.

Simon, Horst D.↗
NASA NTRS1996

NASA EEE Parts and Advanced Interconnect Program (AIP)

none given From Program Objectives: I. Accelerate the readiness of new technologies through development of validation, assessment and test method/tools II. Provide NASA Projects infusion paths for emerging technologies III. Provide NASA Projects technology selection, application and validation guidelines for harware and processes IV. Disseminate quality assurance, reliability, validation, tools and availability information to the NASA community.

NASA EEE Parts Program Advanced Interconnect Progr↗
NASA NTRS2012

Network acceleration techniques

Splintered offloading techniques with receive batch processing are described for network acceleration. Such techniques offload specific functionality to a NIC while maintaining the bulk of the protocol processing in the host operating system ("OS"). The resulting protocol implementation allows the application to bypass the protocol processing of the received data. Such can be accomplished this by moving data from the NIC directly to the application through direct memory access ("DMA") and batch processing the receive headers in the host OS when the host OS is interrupted to perform other work. Batch processing receive headers allows the data path to be separated from the control path. Unlike operating system bypass, however, the operating system still fully manages the network resource and has relevant feedback about traffic and flows. Embodiments of the present disclosure can therefore address the challenges of networks with extreme bandwidth delay products (BWDP).

Crowley, Patricia↗
NASA NTRS2006

Semiautonomous Avionics-and-Sensors System for a UAV

Unmanned Aerial Vehicles (UAVs) autonomous or remotely controlled pilotless aircraft have been recently thrust into the spotlight for military applications, for homeland security, and as test beds for research. In addition to these functions, there are many space applications in which lightweight, inexpensive, small UAVS can be used e.g., to determine the chemical composition and other qualities of the atmospheres of remote planets. Moreover, on Earth, such UAVs can be used to obtain information about weather in various regions; in particular, they can be used to analyze wide-band acoustic signals to aid in determining the complex dynamics of movement of hurricanes. The Advanced Sensors and Electronics group at Langley Research Center has developed an inexpensive, small, integrated avionics-and-sensors system to be installed in a UAV that serves two purposes. The first purpose is to provide flight data to an AI (Artificial Intelligence) controller as part of an autonomous flight-control system. The second purpose is to store data from a subsystem of distributed MEMS (microelectromechanical systems) sensors. Examples of these MEMS sensors include humidity, temperature, and acoustic sensors, plus chemical sensors for detecting various vapors and other gases in the environment. The critical sensors used for flight control are a differential- pressure sensor that is part of an apparatus for determining airspeed, an absolute-pressure sensor for determining altitude, three orthogonal accelerometers for determining tilt and acceleration, and three orthogonal angular-rate detectors (gyroscopes). By using these eight sensors, it is possible to determine the orientation, height, speed, and rates of roll, pitch, and yaw of the UAV. This avionics-and-sensors system is shown in the figure. During the last few years, there has been rapid growth and advancement in the technological disciplines of MEMS, of onboard artificial-intelligence systems, and of smaller, faster, and smarter wireless telemetry systems. The major attraction of MEMS lies in orders-of-magnitude reductions of power requirements relative to traditional electronic components that perform equivalent functions. In addition, the compactness of MEMS, relative to functionally equivalent traditional electronics systems, makes MEMS attractive for UAV applications. Recent advances in MEMS have made it possible to produce pressure, acceleration, humidity, and temperature sensors having masses in subgram range and possessing sensitivities and accuracies comparable to those of larger devices.

Shams, Qamar↗
NASA NTRS1998

g-LIMIT: A Vibration Isolation System for the Microgravity Science Glovebox

For many microgravity science experiments using the Microgravity Science Glovebox (MSG), the ambient acceleration environment will exceed desirable levels. To provide a more quiescent acceleration environment, a vibration isolation system named g-LIMIT (GLovebox Integrated Microgravity Isolation Technology) is being designed. g-LIMIT is the next generation of technology developed for and demonstrated by STABLE on the USML-2 mission in October 1995. Although g-LIMIT is a sub-rack level isolation system that can be used in a variety of applications, g-LIMIT is uniquely optimized for MSG implementation. Standard MSG structural and umbilical interfaces will be used so that the isolation mount is transparent to the user with no additional accommodation requirements. g-LIMIT consists of three integrated isolator modules, each of which is comprised of a dual axis actuator, two axes of acceleration sensing, two axes of position sensing, control electronics, and data transmission capabilities in a minimum-volume package. In addition, this system provides the unique capability for measuring absolute acceleration of the experiment independent of accelerometers as a by-product of the control system and will have the capability of generating pristine accelerations to enhance experiment operations. g-LIMIT is scheduled for flight during the UF-2 mission and will be available to glovebox investigators immediately after characterization testing.

Whorton, Mark S.↗
NASA NTRS2008

Development Status of the J-2X

In June 2006, the NASA Marshall Space Flight Center (MSFC) and Pratt & Whitney Rocketdyne began development of an engine for use on the Ares I crew launch vehicle and the Ares V cargo launch vehicle. The development program will be completed in December 2012 at the end of a Design Certification Review and after certification testing of two flight configuration engines. A team of over 600 people within NASA and Pratt & Whitney Rocketdyne are currently working to prepare for the fall 2008 Critical Design Review (CDR), along with supporting an extensive risk mitigation test program. The J-2X will power the Ares I upper stage and the Ares V earth departure stage (EDS). The initial use will be in the Ares I, used to launch the Orion crew exploration vehicle. In this application, it will power the upper stage after being sent aloft on a Space Shuttle-derived. 5-segment solid rocket booster first stage. In this mission. the engine will ignite at altitude and provide the necessary acceleration force to allow the Orion to achieve orbital velocity. The Ares I upper stage, along with the J-2X. will then be expended. On the Ares V. first stage propulsion is provided by five RS-68B engines and two 5-segment boosters similar to the Ares I configuration. In the Ares V mission. the J-2X is first started to power the EDS and its payload. the Altair lunar lander. into earth orbit, then shut-down and get prepared for its next start. The EDS/Altair will remain in a parking orbit, awaiting rendezvous and docking with Orion. Once the two spacecraft are mated, the J-2X will be restarted to achieve earth departure velocity. After powering the Orion and Altair, the EDS will be expended. By using the J-2X Engine in both applications, a significant infrastructure cost savings is realized. Only one engine development is required, and the sustaining engineering and flight support infrastructures can be combined. There is also flexibility for changing, the production and flight manifest because a single production line can support both missions with minimal differences between each engine configuration kit.

Kynard, Mike↗