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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Perturbation theory for a resistivity shunted Josephson element

We present a systematic perturbation theory, extendable in principle to all orders of magnitude, for the solution of the equations of motion of an ideal Josephson element shunted by a resistance and driven by a dc current source and a small time-dependent source. We present second-order results for the case in which the time dependence is that of a single sinusoid, and these results are compared with other numerical and analytical calculations. Near, but not on, the first constant voltage step where the perturbation theory appears divergent, the current-voltage characteristic is calculated by means of a nonperturbative adiabatic procedure. The impedance and responsivity agree with earlier results.

Thompson, E. D.↗
NASA NTRS1986

Space Station momentum control and reboost requirements for two power generation concepts

Results are presented of dynamic structural analyses of 75 and 300 kW versions of a solar dynamic (SD) power supply for the Space Station (MSS). The SD is being seriously considered as an alternative to solar panels due to lower areal and mass requirements and higher efficiencies. The functioning principle is to use parabolic concentrators to focus sunlight on a heat engine to boil liquids to drive a turbine. Potential problems are foreseen in terms of the torques which would be experienced by the MSS and the subsequent orbital stability effects. The stability would be altered by changing aerodynmaic drag, altered moment of inertia and angular momentum and the altered center of mass location. The problem is exacerbated by the need to first equip the MSS with solar panels while the SD technology is developed. The analysis shows that the attitude control system will need to be redesigned and resized to accommodate MSS growth with either power system. The effects of the rotating parts of the SD system can be minimized, but further studies are required to determine the effects on the pointing accuracy of the SD, which must be 10 times as precise as that needed by a photovoltaic array.

Farmer, J. T.↗
NASA NTRS1987

Color enhancement of highly correlated images. II - Channel ratio and 'chromaticity' transformation techniques

Two techniques for enhancing the color of multispectral images are described; both involve ratioing of data from different image channels. In the first technique, the ratioed data are assigned the primary color for display as color ratio pictures, and in the second method, image data are transformed to RGB chromaticity coordinates by ratioing the data acquired in three channels to the sum of their intensities. The two techniques are applied to a NASA Thermal-IR Multispectral Scanner (TIMS) image of Death Valley and to a Landsat MSS image of the Mojave Desert. The basic principles of ratioing are discussed, and the effects of atmospheric path radiances on the interpretation of ratioed images are investigated. It is observed that the color pictures produced using these two enhancement techniques are similar to the pictures enhanced by decorrelation and hue-saturation-intensity methods.

Gillespie, Alan R.↗
NASA NTRS1993

An autonomous satellite architecture integrating deliberative reasoning and behavioural intelligence

This paper describes a method for the design of autonomous spacecraft, based upon behavioral approaches to intelligent robotics. First, a number of previous spacecraft automation projects are reviewed. A methodology for the design of autonomous spacecraft is then presented, drawing upon both the European Space Agency technological center (ESTEC) automation and robotics methodology and the subsumption architecture for autonomous robots. A layered competency model for autonomous orbital spacecraft is proposed. A simple example of low level competencies and their interaction is presented in order to illustrate the methodology. Finally, the general principles adopted for the control hardware design of the AUSTRALIS-1 spacecraft are described. This system will provide an orbital experimental platform for spacecraft autonomy studies, supporting the exploration of different logical control models, different computational metaphors within the behavioral control framework, and different mappings from the logical control model to its physical implementation.

Lindley, Craig A.↗
NASA NTRS1993

Specification list and function structure for a full-body dynamometer to be used aboard Space Station Freedom

NASA has a need for a machine which can be used as an exercise device and as an instrument to measure an astronaut's muscle performance. The purpose of the exercise device is to work various muscle groups of the astronaut to prevent muscle atrophy, the loss of muscle strength and mass from prolonged exposure to a microgravity environment. The measurement part of the machine will be used to collect data on the strength and power of the astronaut's muscle groups to be used in studies examining the effects of prolonged space inhabitation. The principle device used in this machine to both exercise and measure muscle performance is the dynamometer. The dynamometer converts electrical energy to mechanical energy and mechanical energy to electrical energy or signals. The task of the designer will be to incorporate a dynamometer into a device which can meet all of the needs discussed above. This memorandum has two sections which clarify the design task of producing a full-body dynamometer. The first section is a specification list. The specification list provides the requirements that the designer must meet in his/her design. The second part is a function structure. The function structure shows graphically the flow of material, energy, and information through the machine. These two items will be used by the designer in the design process for the full-body dynamometer.

Mcmahan, Robert↗
NASA NTRS1993

Selection criteria and facilitation training for the study of groupware

Computer support for planning and decision making groups is a growing trend in the 90s. Groupware is a name often applied to group software and has been defined as 'computer-based systems that support groups engaged in a common task (or goal) and that provide an interface to a shared environment'. Unlike most single-user software, groupware assists user groups in their collaboration, coordination, and communication efforts. This paper focuses on groupware to support the meeting process. These systems are often called group decision support systems (GDSS), electronic meeting systems (EMS), or group support systems (GSS). The term 'meeting support groupware' is used here to include any computer-based system to support meetings. In order to understand this technology, one must first understand groups, what they do and the problems they face, and groupware, a wide range of technology to support group work. Guidelines for selecting groups for study as part of an overall research plan are provided in this document. These were taken from the literature and from persons for whom the information in this paper was targeted. Also, guidelines for facilitation training are discussed. Familiarity with known and accepted techniques are the principle duties of the facilitator and any form of training must include practice in using these techniques.

Robichaux, Barry P.↗
NASA NTRS1995

Analysis of solar spectral irradiance measurements from the SBUV/2-series and the SSBUV instruments

The principle purpose of this work is to use yearly flights of the Shuttle SBUV/w (SSBUV) instrument to maintain the long-term calibration of the NOAA-11 SBUV/2 instrument. During this period of performance we have begun updating the NOAA-11 SBUV/2 characterization and have further refined the SSBUV calibration, both steps which must be completed before the long-term calibration of the SBUV/2 can be completed. We have also performed a first attempt of the calibration transfer, demonstrating the viability of the transfer process.

Cebula, Richard P.↗
NASA NTRS1998

Advanced High Brilliance X-Ray Source

The possibility to dramatically increase the efficiency of laboratory based protein structure measurements through the use of polycapillary X-ray optics was investigated. This project initiated April 1, 1993 and concluded December 31, 1996 (including a no cost extension from June 31, 1996). This is a final report of the project. The basis for the project is the ability to collect X-rays from divergent electron bombardment laboratory X-ray sources and redirect them into quasiparallel or convergent (focused) beams. For example, a 0.1 radian (approx. 6 deg) portion of a divergent beam collected by a polycapillary collimator and transformed into a quasiparallel beam of 3 millradian (0.2 deg) could give a gain of 6(exp 2)/0.2(exp 2) x T for the intensity of a diffracted beam from a crystal with a 0.2 deg diffraction width. T is the transmission efficiency of the polycapillary diffraction optic, and for T=0.5, the gain would be 36/0.04 x O.5=45. In practice, the effective collection angle will depend on the source spot size, the input focal length of the optic (usually limited by the source spot-to-window distance on the x-ray tube) and the size of the crystal relative to the output diameter of the optic. The transmission efficiency, T, depends on the characteristics (fractional open area, surface roughness, shape and channel diameter) of the polycapillary optic and is typically in the range 0.2-0.4. These effects could substantially reduce the expected efficiency gain. During the course of this study, the possibility to use a weakly focused beam (0.5 deg convergence) was suggested which could give an additional 10-20 X efficiency gain for small samples . Weakly focused beams from double focusing mirrors are frequently used for macromolecular crystallography studies. Furthermore the crystals are typically oscillated by as much as 2 deg during each X-ray exposure in order to increase the reciprocal space (number of crystal planes) sampled and use of a slightly convergent beam could, in principle, provide a similar sampling benefit without oscillation. Although more problematic, because of complications in analyzing the diffraction patterns, it was also suggested that even more extreme beam convergence might be used to give another order of magnitude intensity gain and even smaller focused spot size which could make it possible to study smaller protein crystals than can be studied using standard laboratory based X-ray diffraction systems. This project represents the first systematic investigation of these possibilities. As initially proposed, the contract included requirements for design, purchase, evaluation and delivery of three polycapillary lenses to the Laboratory for Structural Biology at MSFC and demonstration of such optics at MSFC for selected protein crystal diffraction applications.

Gibson, Walter M.↗
NASA NTRS2005

Going to the Bottom of the Explosion that Formed Cas A

The purpose of this INTEGRAL AO 1 proposal was to observe the gamma-ray lines at 1157 keV, as well as 68 keV and 78 keV of the (44)Ti decay chain from the youngest known galactic supernova remnant Cas A. The radioactive decay of (44)Ti in Cas A was first detected by COMPTEL in the 1157 keV line and later confirmed in the lower energy lines using BeppoSAX data. Despite the second confirming measurement, the flux value still has a considerable error, due to a low signal over background ratio and the poor definition of the continuum background in the range of 70 - 100 keV above the line energies. In addition to improving this flux measurement, INTEGRAL has the unique capability, in principle, to measure the line width of the emission. This type of measurement can further constrain supernova explosion models. Unfortunately, the INTEGRAL instrumental background, especially in the SPI spectrometer, turned out to be significantly higher than estimated at the time of proposal submission before launch. This, and to a smaller extent the reduced effective exposure time of about 1.5 Ms compared to requested 2.5 Ms, has precluded us from reaching the sensitivity necessary for this measurement. Studies of the background variability with the goal of improving background modeling are ongoing, and additional 2.5 Ms observing time has just been approved for the next observing cycle.

Oberlack, Uwe↗
NASA NTRS1996

First-Order System Least Squares for Velocity-Vorticity-Pressure Form of the Stokes Equations, with Application to Linear Elasticity

In this paper, we study the least-squares method for the generalized Stokes equations (including linear elasticity) based on the velocity-vorticity-pressure formulation in d = 2 or 3 dimensions. The least squares functional is defined in terms of the sum of the L(exp 2)- and H(exp -1)-norms of the residual equations, which is weighted appropriately by by the Reynolds number. Our approach for establishing ellipticity of the functional does not use ADN theory, but is founded more on basic principles. We also analyze the case where the H(exp -1)-norm in the functional is replaced by a discrete functional to make the computation feasible. We show that the resulting algebraic equations can be uniformly preconditioned by well-known techniques.

Cai, Zhiqiang↗
NASA NTRS1975

Large Angle Satellite Attitude Maneuvers

Two methods are proposed for performing large angle reorientation maneuvers. The first method is based upon Euler's rotation theorem; an arbitrary reorientation is ideally accomplished by rotating the spacecraft about a line which is fixed in both the body and in space. This scheme has been found to be best suited for the case in which the initial and desired attitude states have small angular velocities. The second scheme is more general in that a general class of transition trajectories is introduced which, in principle, allows transfer between arbitrary orientation and angular velocity states. The method generates transition maneuvers in which the uncontrolled (free) initial and final states are matched in orientation and angular velocity. The forced transition trajectory is obtained by using a weighted average of the unforced forward integration of the initial state and the unforced backward integration of the desired state. The current effort is centered around practical validation of this second class of maneuvers. Of particular concern is enforcement of given control system constraints and methods for suboptimization by proper selection of maneuver initiation and termination times. Analogous reorientation strategies which force smooth transition in angular momentum and/or rotational energy are under consideration.

Cochran, J. E.↗
NASA NTRS1975

Plant, soil, and shadow reflectance components of row crops

Data from the first Earth Resource Technology Satellite (LANDSAT-1) multispectral scanner (MSS) were used to develop three plant canopy models (Kubelka-Munk (K-M), regression, and combined K-M and regression models) for extracting plant, soil, and shadow reflectance components of cropped fields. The combined model gave the best correlation between MSS data and ground truth, by accounting for essentially all of the reflectance of plants, soil, and shadow between crop rows. The principles presented can be used to better forecast crop yield and to estimate acreage.

Richardson, A. J.↗
NASA NTRS2016

Agile: From Software to Mission System

The Resource Prospector (RP) is an in-situ resource utilization (ISRU) technology demonstration mission, designed to search for volatiles at the Lunar South Pole. This is NASA's first near real time tele-operated rover on the Moon. The primary objective is to search for volatiles at one of the Lunar Poles. The combination of short mission duration, a solar powered rover, and the requirement to explore shadowed regions makes for an operationally challenging mission. To maximize efficiency and flexibility in Mission System design and thus to improve the performance and reliability of the resulting Mission System, we are tailoring Agile principles that we have used effectively in ground data system software development and applying those principles to the design of elements of the mission operations system.

software engineering↗
NASA NTRS1991

The detection of the electric field vertical distribution underneath thundercloud: Principle and applications

During the Florida 89 experiment at Kennedy Space Center, a new system was used in order to obtain the vertical distribution of the electric field underneath thunderstorms. It consists of a standard shutter field mill at ground level and five other field sensors suspended from a cable fastened to a tethered balloon located at an altitude of about 1000 meters. It also includes a reception station for telemetered information transmitted by sensors, a processing system in order to store data, and real time display on a screen to show the simultaneous field variations at each level along with the instantaneous electric field profile. The first results obtained show the great importance of the electric field vertical distribution. The field detected at a height of 600m reaches 65 kV/m while that at the surface does not exceed 5 kV/m. The field intensity in altitude is a better criterion for determining the right moment to launch a rocket devoted to flash triggering. Using Gauss's law, the simultaneous field variations at several levels are used in order to evaluate charge densities. Average values close to 1nC.m(-3) are calculated in layers up to 600 m. The calculation of different average charge densities leads to the characterization of the layer between cloud and ground just before the leader propagation in the case of cloud to ground flash.

Soula, Serge↗
NASA NTRS1994

Active control of turbomachine discrete tones

This paper was directed at active control of discrete frequency noise generated by subsonic blade rows through cancellation of the blade row interaction generated propagating acoustic waves. First discrete frequency noise generated by a rotor and stator in a duct was analyzed to determine the propagating acoustic pressure waves. Then a mathematical model was developed to analyze and predict the active control of discrete frequency noise generated by subsonic blade rows through cancellation of the propagating acoustic waves, accomplished by utilizing oscillating airfoil surfaces to generate additional control propagating pressure waves. These control waves interact with the propagating acoustic waves, thereby, in principle, canceling the acoustic waves and thus, the far field discrete frequency tones. This model was then applied to a fan exit guide vane to investigate active airfoil surface techniques for control of the propagating acoustic waves, and thus the far field discrete frequency tones, generated by blade row interactions.

Fleeter, Sanford↗
NASA NTRS2001

A {1,2}-Order Plate Theory Accounting for Three-Dimensional Thermoelastic Deformations in Thick Composite and Sandwich Laminates

A {1,2}-order theory for laminated composite and sandwich plates is extended to include thermoelastic effects. The theory incorporates all three-dimensional strains and stresses. Mixed-field assumptions are introduced which include linear in-plane displacements, parabolic transverse displacement and shear strains, and a cubic distribution of the transverse normal stress. Least squares strain compatibility conditions and exact traction boundary conditions are enforced to yield higher polynomial degree distributions for the transverse shear strains and transverse normal stress through the plate thickness. The principle of virtual work is used to derive a 10th-order system of equilibrium equations and associated Poisson boundary conditions. The predictive capability of the theory is demonstrated using a closed-form analytic solution for a simply-supported rectangular plate subjected to a linearly varying temperature field across the thickness. Several thin and moderately thick laminated composite and sandwich plates are analyzed. Numerical comparisons are made with corresponding solutions of the first-order shear deformation theory and three-dimensional elasticity theory. These results, which closely approximate the three-dimensional elasticity solutions, demonstrate that through - the - thickness deformations even in relatively thin and, especially in thick. composite and sandwich laminates can be significant under severe thermal gradients. The {1,2}-order kinematic assumptions insure an overall accurate theory that is in general superior and, in some cases, equivalent to the first-order theory.

Tessler, A.↗
NASA NTRS2016

Neural Network (NN) Retrievals of Stratocumulus Cloud Properties Using Multiangle Polarimetric Observations During ORACLES

The ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign is taking place in the SouthEast Atlantic during the Austral Spring for three consecutive years from 20162018. The study area encompasses one of the Earths three semipermanent subtropical Stratocumulus (Sc) cloud decks,and experiences very large aerosol optical depths, mainly biomass burning, originating from Africa. Over time, cloud optical depth (COD), lifetime and cloud microphysics (number concentration, effective radii Reff and precipitation) are expected to be influenced by indirect aerosol effects. These changes play a key role in the energetic balance of the region, and are part of the core investigation objectives of the ORACLES campaign, which acquires measurements of clean and polluted scenes of above cloud aerosols (ACA). Simultaneous retrievals of aerosol and cloud optical properties are being developed (e.g. MODIS, OMI), butstill challenging, especially for passive, single viewing angle instruments. By comparison, multiangle polarimetric instruments like RSP (Research Scanning Polarimeter) show promise for detection and quantification of ACA, however, there are no operational retrieval algorithms available yet. Here we describe anew algorithm to retrieve cloud and aerosol optical properties from observations by RSP flown on the ER2and P3 during the 2016 ORACLES campaign. The algorithm is based on training a NN, and is intended to retrieve aerosol and cloud properties simultaneously. However, the first step was to establish the retrievalscheme for low level Sc cloud optical properties. The NN training was based on simulated RSP total and polarized radiances for a range of COD, Reff, and effective variances, spanning 7 wavelength bands and 152 viewing zenith angles. Random and correlated noise were added to the simulations to achieve a morerealistic representation of the signals. Before introducing the input variables to the network, the signals are projected on a principle component plane that retains the maximal signal information but minimizes the noise contribution. We will discuss parameter choices for the network and present preliminary results of cloudretrievals from ORACLES, compared with standard RSP low-levelcloud retrieval method that has been validated against in situ observations.

Cloud-aerosol↗
NASA NTRS1984

Computational aerodynamics and artificial intelligence

The general principles of artificial intelligence are reviewed and speculations are made concerning how knowledge based systems can accelerate the process of acquiring new knowledge in aerodynamics, how computational fluid dynamics may use expert systems, and how expert systems may speed the design and development process. In addition, the anatomy of an idealized expert system called AERODYNAMICIST is discussed. Resource requirements for using artificial intelligence in computational fluid dynamics and aerodynamics are examined. Three main conclusions are presented. First, there are two related aspects of computational aerodynamics: reasoning and calculating. Second, a substantial portion of reasoning can be achieved with artificial intelligence. It offers the opportunity of using computers as reasoning machines to set the stage for efficient calculating. Third, expert systems are likely to be new assets of institutions involved in aeronautics for various tasks of computational aerodynamics.

Mehta, U. B.↗