SEARCH · Engineering Papers
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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The results of a simulation study to predict the IUE imaging chain performance are presented, including simulation photographs and transparencies of ultraviolet echelle spectra. Errors in wavelength determination and radiometric measurements due to system degradation are indicated to be minor. Some order overlap is predicted at the bottom of the echelle format.
The use of Cibachrome products as a solution to problems encountered when contact printing Kodak film type SO-397 onto Kodak Ektrachrome color reversal paper type 1993 is investigated. A roll of aerial imagery consisting of Kodak film types SO-397 and 2443 was contact printed onto Cibachrome and Kodak materials and compared in terms of color quality, resolution, cost, and compatibility with existing equipment and techniques. Objective measurements are given in terms of resolution and sensitometric response. Comparison prints and transparencies were viewed and ranked according to overall quality and aesthetic appeal. It is recommended that Cibachrome Print material be used in place of Kodak Ektachrome paper because it is more easily processed, the cost is equivalent, and it provides improved resolution, color quality, and image fade resistance.
Ten ohm-cm silicon solar cells, 0.2 mm thick, were produced with short circuit current efficiencies up to thirteen percent and using a combination of recent technical advances. The cells were fabricated in conventional and wraparound contact configurations. Improvement in cell collection efficiency from both the short and long wavelengths region of the solar spectrum was obtained by coupling a shallow junction and an optically transparent antireflection coating with back surface field technology. Both boron diffusion and aluminum alloying techniques were evaluated for forming back surface field cells. The latter method is less complicated and is compatible with wraparound cell processing.
Inversion layer solar cells were fabricated by etching through the diffused layer on p-type silicon wafers in a comb-like contact pattern. The charge separation comes from an induced p-n junction at the surface. The inverted surface is caused by a layer of transparent material applied to the surface that either contains free positive ions or that creates donor states at the interface. Cells are increased from 3 ma I sub sc to 100 ma by application of sodium silicate. The action is unstable, however, and decays. Non-mesa contaminated oxide cells were fabricated with short circuit currents of over 100 ma measured in the sun. Cells of this type have demonstrated stability.
Based on the hypothesis that the number of atoms per unit volume, accurately calculable for any substance of known real density and chemical composition, various characterizing parameters (energy levels of electrons interacting among atoms of the same or different kinds, atomic mass, bond intensity) were chosen for study. A multiple exponential equation was derived to express the relationship. Various properties were examined, and correlated with the various parameters. Some of the properties considered were: (1) heat of atomization, (2) boiling point, (3) melting point, (4) shear elastic modulus of cubic crystals, (5) thermal conductivity, and (6) refractive index for transparent substances. The solid elements and alkali halides were the materials studied. It is concluded that the number of different properties can quantitively be described by a common group of parameters for the solid elements, and a wide variety of compounds.
The net radiation method is developed for systems having both opaque and partially transparent walls. Heat convection is present at the surfaces and heat conduction through the windows is taken into account. Specific equations are derived for a window between two parallel plates, where one plate is at an elevated temperature typical of what would be encountered in an electric furnace, and the other plate is being cooled. A two-band model is used with cutoff wavelengths typical of glass or quartz. Numerical results are obtained for the window temperature and the heat flow through the window. The effect on these quantities of various plate temperatures and emissivities is shown.
Plans for Pioneer 11's approach to Saturn are described. A flyby somewhat parallel to the ring plane is being proposed as an interim target, with a future option held for a possible high risk (or suicide) plunge through the nearly transparent space between Saturn and its rings.
Numerical or analytical analyses were performed on seven different test specimens including blister test, 90-degree peel test, torsion test, and various cone tests. These specimens are in general subjected to complex stress fields having various amounts of Mode I, Mode II, and Mode III loads. The specimens were then constructed using polymethyl methacrylate for the adherends and a transparent polyurethane elastomer (Solithane 113) for the adhesive. This combination permitted direct observation of the bondline as load was applied. Although initial debonds as well as bond end termination singularities were present in all specimens, in some cases the debond did not initiate at the singularity points as would normally have been expected. An explanation for this behavior is presented, as well as a comparison of loading mode effect on those specimens for which the debond did propagate from a bond terminus singular point.
The materials studied are described along with the apparatus and the experimental techniques employed. The results of the measurements involving two REI Silica materials and a Mod 1 B REI Mullite are listed in a table. Measurements were conducted at unusually high temperature differences to detect 'shine-through' radiation transparency. Photographs are presented of the high-temperature guarded hot plate assembly.
Transparent laminates containing imbedded crystals of various ionic and nonionic substances were prepared and their swelling in distilled water was observed. It was found that under certain conditions, disk-shaped cracks formed around the swollen pockets containing a dissolving crystal. Such cracks can form before equilibrium swelling is reached and may severely damage the elastomer.
A glass spherule of the form of a flattened spheroid measuring 580 microns in diameter is studied. The spherule is transparent, shiny, and of a yellowish brown tint. It contains a number of central and peripheral spherical bubble-type cavities. The surface and morphology features resemble those of Apollo spherules, but differ in chemical composition, which is close to that of the Luna-16 regolith.
Aluminum nitride films have been deposited on silicon substrates at 800-1200 C by the pyrolysis of an aluminum trichloride-ammonia complex, AlCl3.3NH3, in a gas flow system. The deposit was transparent, tightly adherent to the substrate, and was confirmed to be aluminum nitride by X-ray and electron diffraction techniques. The deposited aluminum nitride films were found to be polycrystalline with the crystallite size increasing with increasing temperature of deposition. Other properties of aluminum nitride films relevant to device applications, including density, refractive index, dissolution rate, dielectric constant, and masking ability, have been determined. These properties indicate that aluminum nitride films have potential as a dielectric in electronic devices.
A new, high-performance device has been developed for application to real-time coherent optical data processing. The new device embodies a CdS photoconductor, a CdTe light-absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The noncoherent image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the ac voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state and the optical birefringence effect to create the bright on-state. The liquid crystal modulates the polarization of the coherent read-out light so an analyzer must be used to create an intensity modulated output beam.
A new perturbation expansion is derived for the structure of rotating bodies in hydrostatic equilibrium. The method uses an expansion of the density on Legendre polynomial functions of angle, and can be developed analytically in a manner analogous to the standard level-surface perturbation theory. The new theory proceeds from a prescribed pressure-density relation rather than from a prescribed density distribution, and is both simpler and more physically transparent than the level-surface approach. High zonal harmonics are shown to arise via a transfer function involving derivatives of the interior sound velocity, and via mixing of multipole density components in the outer shell of the planet. Sample calculations for polytropic sequences are presented, as well as standard gravity models for Jupiter and Saturn. Mathematical subleties of the theory are discussed in an appendix.
Calculations of the expected crystallization behavior of selected lunar compositions (60095 and 14259) are presented. Knowledge of this behavior combined with measurements of the state of crystallinity in partially devitrified lunar samples permits the determination of the thermal history of the samples. The state of crystallinity of a specimen is described by a statistical crystal distribution function psi. The heat flow problems of a plate of opaque glass quenched on an aluminum block and of a semi-transparent glass sphere cooling by radiation are analyzed. The results are combined with laboratory measurements of the crystal growth velocity and the viscosity, and with theoretical expressions for the nucleation frequency (homogeneous and heterogeneous) to obtain psi. It is found that the calculated psi is much too large in comparison with laboratory experiments on lunar samples. Possible reasons for the discrepancy are discussed, and the most likely cause is that the assumed nucleation barrier is too small. It also appears likely that these materials have relatively few nucleating heterogeneities.
The effects of vibration, flow transients, and warm gas pressurization on capillary acquisition system performance were evaluated. The degradation observed under wide band random and high frequency sinusoidal vibration was of a substantially different nature from that obtained under low frequency sinusoidal vibration. With the former, ingestion of small gas bubbles into the liquid region was correlated by a hydrostatic model, while the capillary stability was destroyed and liquid was lost from the liquid region with the latter. No degradation was observed as a result of flow transients in a flight-type multichannel screen device, but it was observed in a transparent laboratory device. Liquid hydrogen outflow tests were conducted with a multilayer dual-screen-liner system with both helium and hydrogen pressurant gases. The tendency towards dryout of the device with hydrogen pressurant was found to increase with increasing pressurant temperature and length of prepressurization period. Dryout did not occur with helium pressurant.
Optical system consists of two filter layers with each layer composed of transparent stripes alternating with dichroic color filter strips. System produces color multiplexed light signal by vertically orienting dichroic filter stripes perpendicular to scan lines of image tube.
Single corona-discharge needle is used to apply uniform charge to thermoplastic medium in holograph-storage system. Needle is connected to flat transparent electrode that is parallel to thermoplastic.