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All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Description of MSFC engineering photographic analysis

Utilizing a background that includes development of basic launch and test photographic coverage and analysis procedures, the MSFC Photographic Evaluation Group has built a body of experience that enables it to effectively satisfy MSFC's engineering photographic analysis needs. Combining the basic soundness of reliable, proven techniques of the past with the newer technical advances of computers and computer-related devices, the MSFC Photo Evaluation Group is in a position to continue to provide photo and video analysis service center-wide and NASA-wide to supply an improving photo analysis product to meet the photo evaluation needs of the future; and to provide new standards in the state-of-the-art of photo analysis of dynamic events.

Earle, Jim↗
NASA NTRS1988

A calorimetric determination of the enthalpy of formation and a description of the defect structure of the ordered beta-phase /Ni, Cu/ /1-x/ Al/x/

In order to describe thermodynamically the defect structure of an ordered B-Hume-Rothery phase, the heat of formation of (Ni,Cu)(1-x)Al(x) was measured at 1100 K as a function of concentration in the range x (sub Al) = 0.4 and 0.55 for three substitution rations x (sub Ni)/x (sub Cu) = infinity; 11; 5. The heat of formation of the NiAl beta-phase is strongly negative. For the stoichiometric composition it is -72.2 kJ/g-atom. On both the nickel-rich side and the aluminum-rich side the magnitude of the enthalpy of formation decreases linearly with concentration. Substitution of nickel for copper decreases the magnitude of the enthalpy of formation over the entire homogeneity range for the phase (Ni,Cu)(1-x)Al(x). The curve for the enthalpy of formation as well as the literature values for the chemical potential of aluminum are described with great accuracy by the disorder model of Wagner-Schottky.

Henig, E. T.↗
NASA NTRS1987

Space experiments with particle accelerators (SEPAC): Description of instrumentation

SEPAC (Space Experiments with Particle Accelerators) flew on Spacelab 1 (SL 1) in November and December 1983. SEPAC is a joint U.S.-Japan investigation of the interaction of electron, plasma, and neutral beams with the ionosphere, atmosphere and magnetosphere. It is scheduled to fly again on Atlas 1 in August 1990. On SL 1, SEPAC used an electron accelerator, a plasma accelerator, and neutral gas source as active elements and an array of diagnostics to investigate the interactions. For Atlas 1, the plasma accelerator will be replaced by a plasma contactor and charge collection devices to improve vehicle charging meutralization. This paper describes the SEPAC instrumentation in detail for the SL 1 and Atlas 1 flights and includes a bibliography of SEPAC papers.

Taylor, W. W. L.↗
NASA NTRS1988

Description of an oscillating flow pressure drop test rig

A test rig designed to generate heat exchanger pressure drop information under oscillating flow conditions is described. This oscillating flow rig is based on a variable stroke and variable frequency linear drive motor. A frequency capability of 120 hertz and a mean test pressure up to 15 mPA (2200 psi) allows for testing at flow conditions found in modern high specific power Stirling engines. An important design feature of this rig is that it utilizes a single close coupled dynamic pressure transducer to measure the pressure drop across the test sample. This eliminates instrumentation difficulties associated with the pressure sensing lines common to differential pressure transducers. Another feature of the rig is that it utilizes a single displacement piston. This allows for testing of different sample lengths and configurations without hardware modifications. All data acquisition and reduction for the rig is performed with a dedicated personal computer. Thus the overall system design efficiently integrates the testing and data reduction procedures. The design methodology and details of the test rig is described.

Wood, J. Gary↗
NASA NTRS1988

Description of graphics translation software between Intergraph and Tektronix systems

The requirement for Marshall Space Flight Center's Photo Analysis to use existing 3-D Intergraph graphic files on an existing Tektronix 4129 3-D graphics workstation and the unavailability of an off-the-shelf Intergraph to Tektronix translator required the development of such a translater. Using the output of Intergraph's standard interchange format converter, the 3-D graphic information of Intergraph's files are reformatted and compressed. The 3-D image is reconstructed using Tektronix's software terminal interface graphic library (STI).

Rieckhoff, Tom↗
NASA NTRS1988

The eivaN: A forward-looking interactive orbital trajectory plotting tool for use with proximity operations (PROX OPS) and other maneuvers: Description and user's manual

The results of vehicle burns on-orbit are very difficult to anticipate because of nonlinearities in the equations of motion governing orbiting bodies. This confusion was noticed firsthand in prior experimentation. Out of plane motion is relatively simple as it is uncoupled from the other two degrees of freedom. However, in plane thrusts are more complex because the motions resulting from these inputs are coupled. An interactive planning device, eivaN, was developed to plot resulting trajectories, to provide a better comprehension of orbital mechanics effects, and to help the user to develop heuristics for on-orbit mission planning. The eivaN runs with Microsoft Excel on a Macintosh computer. It provides a forward looking display: burn parameters in the three orthogonal axes in addition to time inputted, and the resultant trajectory is then plotted. Position and velocity components for any burn at any user specified time are readily available. A new area of research related to the human factors of real time, on-orbit mission planning was identified and is currently being investigated.

Brody, Adam R.↗
NASA NTRS1988

Range data description based on multiple characteristics

An algorithm for describing range images based on Mean curvature (H) and Gaussian curvature (K) is presented. Range images are unique in that they directly approximate the physical surfaces of a real world 3-D scene. The curvature parameters are derived from the fundamental theorems of differential geometry and provides visible invariant pixel labels that can be used to characterize the scene. The sign of H and K can be used to classify each pixel into one of eight possible surface types. Due to the sensitivity of these parameters to noise the resulting HK-sing map does not directly identify surfaces in the range images and must be further processed. A region growing algorithm based on modeling the scene points with a Markov Random Field (MRF) of variable neighborhood size and edge models is suggested. This approach allows the integration of information from multiple characteristics in an efficient way. The performance of the proposed algorithm on a number of synthetic and real range images is discussed.

Al-Hujazi, Ezzet↗
NASA NTRS1987

Quadrupole source in prediction of the noise of rotating blades - A new source description

The aim of this paper is to perform a theoretical study of the quadrupole term of the Ffowcs Williams-Hawkings (FW-H) equation to obtain practical results for applications to rotating blades. The quadrupole term of the FW-H equation is algebraically manipulated into volume, surface and line sources using generalized function theory and differential geometry. The volume source is of the type in Lighthill's jet noise theory. The surface sources are on the blade and shock surfaces and the line source is at the trailing edge. It is shown that contribution of volume sources in the boundary layer and wakes can be written in the form of surface integrals. It is argued that the surface and line sources and the part of the volume sources in the boundary layer, wakes and vortices near the blades should be sufficient in calculation of the noise of high speed rotating blades. The integrals correspoding to the various sources appearing in the formula for calculation of the acoustic pressure are briefly derived.

Farassat, F.↗
NASA NTRS1987

Description of the mean behaviour of ionospheric plasma temperatures

A status report on the empirical modeling of ionospheric electron and ion temperatures is given with special emphasis on the models used in the International Reference Ionosphere (IRI). Electron temperature models have now reached a state where reliable prediction of the mean altitudinal, latitudinal and diurnal variations is possible. These models are largely based on satellite measurements, but comparisons with incoherent scatter radar measurements have shown excellent agreement. Variations with season and magnetic and solar activity seem to be small and are not yet included consistently in these models. Similar to the electron temperature, the ion temperature shows the largest variations with altitude, latitude and local time. But due to the larger mass, these variations are smoother and more steady in the case of the ions and therefore easier to model. Nevertheless, very few ion temperature models exist. The IRI model takes advantage of the observed concurrence of the ion temperature with the neutral temperature at low altitudes and with the electron temperature at high altitudes.

Bilitza, Dieter↗
NASA NTRS1988

Dependence of rate constants on vibrational temperatures - An Arrhenius description

An interpretation of the variation of rate constants with vibrational temperature is proposed which introduces parameters analogous to those of the classical Arrhenius expression. The constancy of vibrational activation energy is studied for the dissociaton of NO, the ion-molecular reaction of O(+) with N2, and the atom exchange reaction of I with H2. It is found that when a Boltzmann distribution for vibrational states is applicable, the variation of the rate constant with the vibrational temperature can be used to define a vibrational activation energy. The method has application to exchange reactions where a vibrational energy threshold exists.

Ford, D. I.↗
NASA NTRS1988

An expert system for probabilistic description of loads on space propulsion system structural components

LDEXPT, an expert system that generates probabilistic characterizations of the loads spectra borne by spacecraft propulsion systems' structural components, is found by recent experience at NASA-Lewis to be useful in the cases of components representative of the Space Shuttle Main Engine's turbopumps and fluid transfer ducting. LDEXPT is composed of a knowledge base management system and a rule base management system. The ANLOAD load-modeling module of LDEXPT encompasses three independent probabilistic analysis techniques.

Spencer, B. F., Jr.↗
NASA NTRS1987

How important is correlation in the description of the Ni-H2O interaction

Using very large basis sets, which can accurately describe the polarizability of Ni and H2O and the dipole moment of H2O, the dipole-induced-dipole interaction is shown to be more than 50 percent of the about 4.8 kcal/mole bonding. Dispersion is found to account for the remainder of the bonding; this is significantly less than in previous estimates. The superposition error at the SCF level is essentially zero, and only 0.5 kcal/mole at the SDCI level, and the binding energy has been corrected for this error.

Bauschlicher, Charles W., Jr.↗
NASA NTRS1988

A general model for Io's neutral gas clouds. I - Mathematical description

A general mathematical formalism for calculating the physical properties of any of Io's neutral gas clouds (Na, K, O, S, SO2) is presented. The dynamical effects of both the gravitational fields of Io and Jupiter and solar radiation pressure are included, in addition to the many complex space- and time-dependent interactions that occur between the neutral clouds and the plasma torus. The importance of this new model in studying both the plasma conditions prevalent in the inner planetary magnetosphere and the nature of Io's local atmosphere is discussed. A numerical method for evaluating the physical properties of the neutral clouds using the new model is described.

Smyth, W. H.↗
NASA NTRS1988

A description of electron heating with an electrostatic potential jump in a parallel, collisionless, fire hose shock

The electron heating required if protons scatter elastically in a parallel, collisionless shock is calculated. Near-elastic proton scattering off large amplitude background magnetic field fluctuations might be expected if the waves responsible for the shock dissipation are generated by the fire hose instability. The effects of an electrostatic potential jump in the shock layer are included by assuming that the energy lost by protons in traversing the potential jump is converted into electron thermal pressure. It is found that the electron temperature increase is a strong function of the potential jump. Comparison is made to the parallel shock plasma simulation of Quest (1987).

Ellison, Donald C.↗
NASA NTRS1988

Model description document for a computer program for the emulation/simulation of a space station environmental control and life support system (ESCM)

Emulation/Simulation Computer Model (ESCM) computes the transient performance of a Space Station air revitalization subsystem with carbon dioxide removal provided by a solid amine water desorbed subsystem called SAWD. This manual describes the mathematical modeling and equations used in the ESCM. For the system as a whole and for each individual component, the fundamental physical and chemical laws which govern their operations are presented. Assumptions are stated, and when necessary, data is presented to support empirically developed relationships.

Yanosy, James L.↗
NASA NTRS1987

Flight survey of the 757 wing noise field and its effects on laminar boundary layer transition. Volume 1: Program description and data analysis

It was previously observed that an incident acoustic field on a wing with laminar flow can cause transition to turbulent flow if the fluctuating acoustic velocities are of sufficient amplitude and in the critical frequency range for an unstable laminar boundary layer. A section of a wing was modified with a natural laminar flow (NLF) glove to allow direct measurement of the effect of varying engine noise on the extent of laminar flow. The flight test program was completed in June, 1985. At each flight condition, the engine power was varied from about 2600 r/min (idle) to about 4500 r/min (maximum continuous power). The spectral data provides considerable insight into the influences of the various sound sources that contribute to the overall noise levels. Additional analysis will be required to assess the impact of these sources on boundary layer transition. These results demonstrate that substantial laminar flow on the wing of a transport configuration with wing-mounted engines can be obtained.

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