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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

An engineering analysis of a closed cycle plant growth module

The SOLGEM model is a numerical engineering model which solves the flow and energy balance equations for the air flowing through a growing environment, assuming quasi-steady state conditions within the system. SOLGEM provides a dynamic simulation of the controlled environment system in that the temperature and flow conditions of the growing environment are estimated on an hourly basis in response to the weather data and the plant growth parameters. The flow energy balance considers the incident solar flux; incoming air temperature, humidity, and flow rate; heat exchange with the roof and floor; and heat and moisture exchange with the plants. A plant transpiration subroutine was developed based plant growth research facility, intended for the study of bioregenerative life support theories. The results of a performance analysis of the plant growth module are given. The estimated energy requirements of the module components and the total energy are given.

Stickford, G. H., Jr.↗
NASA NTRS1969

Dynamics of Jupiter's cloud bands

Jupiter upper atmosphere cloud bands zonal motion velocities, examining barotropic stability criterion and geostrophic balance hypothesis

Cuzzi, J. N.↗
NASA NTRS1992

FET's Perform Well At Cryogenic Temperatures

New metal-oxide-semiconductor field-effect transistors designed for source-follower preamplifiers operating at liquid-helium temperatures in conjunction with infrared detectors. Lower thresholds and offset give CryoFET's greater dynamic range and linearity than conventional MOSFET's at low temperatures and facilitates pair balancing to reduce offsets in output. Reduces heat loading of cryogenic system, extending life, reliability, and performance of cryogenic infrared instruments.

Sclar, N.↗
NASA NTRS1993

Parallel processing for nonlinear dynamics simulations of structures including rotating bladed-disk assemblies

The principal objective of this research is to develop, test, and implement coarse-grained, parallel-processing strategies for nonlinear dynamic simulations of practical structural problems. There are contributions to four main areas: finite element modeling and analysis of rotational dynamics, numerical algorithms for parallel nonlinear solutions, automatic partitioning techniques to effect load-balancing among processors, and an integrated parallel analysis system.

Hsieh, Shang-Hsien↗
NASA NTRS2004

Effects of Gravity on Cells, Tissues, and Organisms: Their Implications on Habitat and Human Support in Microgravity

This presentation will demonstrate that gravity plays a major role in advanced human life support in a closed habitat. The examples include, but are not limited to, control of purity in drinking water supplies (application of biocides), control of urine in space rodent habitats and operation of space septic tanks (waste management). Our goal is to understand and determine possible mechanisms that describe the process by which cells anchor to a substrate to form dynamic, vibrant communities of cells which influence human health in absence of gravity. The balance of all forces (mechanotransduction) acting on a cell will determine whether a cell thrives and multiplies or dies in a process called apoptosis and/or necrosis. The balance of forces are tightly coupled to the transport of nutrients and metabolic products (biochemotransduction) to and from the cell interface. We will highlight our effort to improve astronaut health by showing that microgravity life support systems have to be designed differently from those on Earth.

Kizito, John↗
NASA NTRS2018

High-resolution Wave Propagation Method for Stratified Flows

The implementation of the multidimensional f-waves Riemann solver for the time-dependent, three-dimensional, nonhydrostatic, meso- and microscale atmospheric flows is described in detail. The Riemann solver employs flux-based wave decomposition (f-waves) for the calculation of Godunov fluxes in which the flux differences are written directly as the linear combination of the right eigenvectors of the hyperbolic system. The scheme incorporates the source term due to gravity without introducing discretization errors which is an important property in the context of atmospheric flows. The resulting flow solver is conservative, accurate, stable, and well-balanced. The implementation of the solver is evaluated using benchmark test cases for atmospheric dynamics.

Riemann problem↗
NASA NTRS2009

NASA Tech Briefs, September 2009

opics covered include: Filtering Water by Use of Ultrasonically Vibrated Nanotubes; Computer Code for Nanostructure Simulation; Functionalizing CNTs for Making Epoxy/CNT Composites; Improvements in Production of Single-Walled Carbon Nanotubes; Progress Toward Sequestering Carbon Nanotubes in PmPV; Two-Stage Variable Sample-Rate Conversion System; Estimating Transmitted-Signal Phase Variations for Uplink Array Antennas; Board Saver for Use with Developmental FPGAs; Circuit for Driving Piezoelectric Transducers; Digital Synchronizer without Metastability; Compact, Low-Overhead, MIL-STD-1553B Controller; Parallel-Processing CMOS Circuitry for M-QAM and 8PSK TCM; Differential InP HEMT MMIC Amplifiers Embedded in Waveguides; Improved Aerogel Vacuum Thermal Insulation; Fluoroester Co-Solvents for Low-Temperature Li+ Cells; Using Volcanic Ash to Remove Dissolved Uranium and Lead; High-Efficiency Artificial Photosynthesis Using a Novel Alkaline Membrane Cell; Silicon Wafer-Scale Substrate for Microshutters and Detector Arrays; Micro-Horn Arrays for Ultrasonic Impedance Matching; Improved Controller for a Three-Axis Piezoelectric Stage; Nano-Pervaporation Membrane with Heat Exchanger Generates Medical-Grade Water; Micro-Organ Devices; Nonlinear Thermal Compensators for WGM Resonators; Dynamic Self-Locking of an OEO Containing a VCSEL; Internal Water Vapor Photoacoustic Calibration; Mid-Infrared Reflectance Imaging of Thermal-Barrier Coatings; Improving the Visible and Infrared Contrast Ratio of Microshutter Arrays; Improved Scanners for Microscopic Hyperspectral Imaging; Rate-Compatible LDPC Codes with Linear Minimum Distance; PrimeSupplier Cross-Program Impact Analysis and Supplier Stability Indicator Simulation Model; Integrated Planning for Telepresence With Time Delays; Minimizing Input-to-Output Latency in Virtual Environment; Battery Cell Voltage Sensing and Balancing Using Addressable Transformers; Gaussian and Lognormal Models of Hurricane Gust Factors; Simulation of Attitude and Trajectory Dynamics and Control of Multiple Spacecraft; Integrated Modeling of Spacecraft Touch-and-Go Sampling; Spacecraft Station-Keeping Trajectory and Mission Design Tools; Efficient Model-Based Diagnosis Engine; and DSN Simulator.

Source record↗
NASA NTRS1997

System Dynamic Analysis of a Wind Tunnel Model with Applications to Improve Aerodynamic Data Quality

The research investigates the effect of wind tunnel model system dynamics on measured aerodynamic data. During wind tunnel tests designed to obtain lift and drag data, the required aerodynamic measurements are the steady-state balance forces and moments, pressures, and model attitude. However, the wind tunnel model system can be subjected to unsteady aerodynamic and inertial loads which result in oscillatory translations and angular rotations. The steady-state force balance and inertial model attitude measurements are obtained by filtering and averaging data taken during conditions of high model vibrations. The main goals of this research are to characterize the effects of model system dynamics on the measured steady-state aerodynamic data and develop a correction technique to compensate for dynamically induced errors. Equations of motion are formulated for the dynamic response of the model system subjected to arbitrary aerodynamic and inertial inputs. The resulting modal model is examined to study the effects of the model system dynamic response on the aerodynamic data. In particular, the equations of motion are used to describe the effect of dynamics on the inertial model attitude, or angle of attack, measurement system that is used routinely at the NASA Langley Research Center and other wind tunnel facilities throughout the world. This activity was prompted by the inertial model attitude sensor response observed during high levels of model vibration while testing in the National Transonic Facility at the NASA Langley Research Center. The inertial attitude sensor cannot distinguish between the gravitational acceleration and centrifugal accelerations associated with wind tunnel model system vibration, which results in a model attitude measurement bias error. Bias errors over an order of magnitude greater than the required device accuracy were found in the inertial model attitude measurements during dynamic testing of two model systems. Based on a theoretical modal approach, a method using measured vibration amplitudes and measured or calculated modal characteristics of the model system is developed to correct for dynamic bias errors in the model attitude measurements. The correction method is verified through dynamic response tests on two model systems and actual wind tunnel test data.

Buehrle, Ralph David↗
NASA NTRS2002

Load Balancing Strategies for Multi-Block Overset Grid Applications

The multi-block overset grid method is a powerful technique for high-fidelity computational fluid dynamics (CFD) simulations about complex aerospace configurations. The solution process uses a grid system that discretizes the problem domain by using separately generated but overlapping structured grids that periodically update and exchange boundary information through interpolation. For efficient high performance computations of large-scale realistic applications using this methodology, the individual grids must be properly partitioned among the parallel processors. Overall performance, therefore, largely depends on the quality of load balancing. In this paper, we present three different load balancing strategies far overset grids and analyze their effects on the parallel efficiency of a Navier-Stokes CFD application running on an SGI Origin2000 machine.

Djomehri, M. Jahed↗
NASA NTRSDate not supplied

Modeling and Impact of Solar Energetic Particles in the Heliosphere and Geospace

Understanding the radiation environment due to solar energetic particles in the heliosphere and the Earth’s magnetosphere is a challenging and practically important task. Exposure to energetic particles often leads to malfunctions and unexpected failures of electronics onboard spacecraft. The most vulnerable are exploratory missions when outside of the Earth’s magnetosphere. Geomagnetic field deflects Solar Energetic Particles (SEPs) moving through geospace though some of these particles propagate to LEO and have a high penetrating capability, thus producing significant radiation hazards for human spaceflight. Solar energetic particles also have an essential effect on the composition and dynamics of the Earth’s atmosphere. Precipitating SEPs enhance the atmospheric concentration of NOx and HOx, which play a crucial role in the ozone balance in the middle atmosphere by destroying odd oxygen through catalytic reactions. Numerical modeling of the radiation environment due to SEPs in the inner heliosphere and geospace is a multifold problem. That includes simulating 1) solar wind dynamics and the interplanetary magnetic field, 2) global modeling of the Earth’s magnetosphere, and 3) modeling transport and acceleration of SEPs in the inner heliosphere and geospace. The lecture will outline the key physical processes that control the behavior of SEPs in the heliosphere and geospace, along with the contemporary numerical methods used for their modeling. It will primarily focus on describing the SEP population in geospace across different altitudes, ranging from Low Earth Orbit (LEO) through Medium Earth Orbit (MEO) and Geostationary Orbit (GEO), up to the magnetopause, while considering the realistic geomagnetic field. Additionally, the lecture will cover how the SEP population in geospace varies in response to geomagnetic activity. This includes the temporal trapping of SEPs in geospace and the reduction of the rigidity cutoff during geomagnetic storms.

solar energetic particles↗
NASA NTRS1992

An approach for increasing aeroelastic divergence dynamic pressure of wind-tunnel models

An approach for increasing the aeroelastic divergence dynamic pressure of wind-tunnel model support systems is presented. A study has been conducted to investigate the effect of increased flexibility of the forward portion of balances on the divergence pressure of wind-tunnel models. The study utilized prior divergence analyses completed for various models to be tested in NASA Langley Research Center's National Transonic Facility, the Engineering Analysis Language finite-element analysis code, and an in-house computer program which solves for divergence dynamic pressure utilizing a transfer-matrix method based on fourth-order Runge-Kutta integration. Analytical results for balance flexibility changes versus changes in divergence pressure were obtained and demonstrate that a significant increase in divergence pressure can be obtained from the increased flexibility of the balance's forward portion for many models and their support systems.

Edwards, R. W.↗
NASA NTRS1972

Space shuttle: Static aerodynamic characteristics of the MSC-040A the Msc-040A space shuttle orbiter with wedge centerline vertical and twin vertical tails at Mach numbers from 0.6 to 4.96

The results are presented from experimental aerodynamic investigations conducted on a 0.6-percent scale model of the MSC-040 space shuttle orbiter in a 14 inch trisonic wind tunnel. The purpose of the test program was to define the stability, control, and performance characteristics of the baseline MSC-040A orbiter configuration with proposed alternate wing pods, with several vertical tail configurations with and without flared rudders, and with upper wing surface flap deflections. Force and moment data and model base and balance cavity pressure data were obtained for a Mach range of 0.60 through 4.96 and dynamic pressure range of 465 through 1580 psf. Model attitude was varied from 0 to +34 degrees angle of attack at zero sideslip and -4 to +10 degrees angle of sideslip at 0, 10, 20, and 24 degrees angle of attack.

Glass, K. J.↗
NASA NTRS1978

A review of the consequences of fluid and electrolyte shifts in weightlessness

This review describes the renal-endocrine mechanisms related to the early losses of fluid-electrolytes from the body during weightlessness as well as their contribution to longer term adaptation of fluid-electrolyte balance. The hypotheses presented were generated by a systematic analysis of body fluid and renal dynamics observed under conditions of actual and simulated spaceflight. These have increased our understanding of the effects of acute headward fluid shifts on renal excretion, the factors promoting excess sodium excretion and the regulation of extracellular fluid composition.

Leach, C. S.↗
NASA NTRS1986

Integrated analysis tools for trade studies of spacecraft controller and sensor locations

The present investigation was conducted with the aim to evaluate the practicality and difficulties of modern control design methods for large space structure controls. The evaluation is used as a basis for the identification of useful computer-based analysis tools which would provide insight into control characteristics of a spacecraft concept. A description is presented of the wrap-rib antenna and its packaging concept. Attention is given to active control requirements, a mathematical model of structural dynamics, aspects of sensor and actuator location, the analysis approach, controllability, observability, the concept of balanced realization, transmission zeros, singular value plots, analysis results, model reduction, and an interactive computer program. It is pointed out that the application of selected control analysis tools to the wrap-rib antenna demonstrates several capabilities which can be useful during conceptual design.

Rowell, L. F.↗
NASA NTRS1986

The quiet solar transition region

The results of recent studies (in the UV) of the structure and dynamics of the quiet solar transition region and its role in the mass and energy balance of the outer layers of the solar atmosphere are summarized. The region is one in which temperature increases from 25,000 K to about 1 million K and the matter density, fed by the outward flowing wind and the inward streaming plasma, increases by a factor of 40. The morphology of the region is described, along with the theoretical models being applied to the observed nonthermal line broadening, Doppler wavelength shifts, temporal fluctuations, and fine structure. Deficiencies in existing simple models of the region are discussed.

Mariska, John T.↗
NASA NTRS1990

Global variability of water vapor and condensate from SSM/I

In the three years since its launch, the Special Sensor Microwave Imager (SSM/I) provided the beginnings of a data set crucial to the study of the Earth's global hydrologic cycle. Investigations with SSM/I centered largely on two themes: (1) an analysis of the variability in atmospheric moisture as a signature of dynamic and kinematic processes, and (2) development of high quality data sets for determining moisture balance and, eventually, diabatic heating on regional and planetary scales. To date, most of the emphasis has been on the precipitable water field since algorithms for this quantity appear to be the most mature. In addition, researchers began work with liquid water, precipitating ice and ocean surface wind stress fields. The retrievals used in these studies are from algorithms developed by Wentz (RSS Tech Rpt. 1989) and Spencer (1988 JTECH).

Robertson, Franklin R.↗
NASA NTRS1994

High-Speed Optical Wide-Area Data-Communication Network

Proposed fiber-optic wide-area network (WAN) for digital communication balances input and output flows of data with its internal capacity by routing traffic via dynamically interconnected routing planes. Data transmitted optically through network by wavelength-division multiplexing in synchronous or asynchronous packets. WAN implemented with currently available technology. Network is multiple-ring cyclic shuffle exchange network ensuring traffic reaches its destination with minimum number of hops.

Monacos, Steve P.↗
NASA NTRS2002

Ring Current Ion Coupling with Electromagnetic Ion Cyclotron Waves

A new ring current global model has been developed that couples the system of two kinetic equations: one equation describes the ring current (RC) ion dynamic, and another equation describes wave evolution of electromagnetic ion cyclotron waves (EMIC). The coupled model is able to simulate, for the first time self-consistently calculated RC ion kinetic and evolution of EMIC waves that propagate along geomagnetic field lines and reflect from the ionosphere. Ionospheric properties affect the reflection index through the integral Pedersen and Hall conductivities. The structure and dynamics of the ring current proton precipitating flux regions, intensities of EMIC global RC energy balance, and some other parameters will be studied in detail for the selected geomagnetic storms.

Khazanov. G. V.↗