SEARCH · Engineering Papers

Results for “Improved”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85

All sources NASA NTRS DOE OSTI

NASA NTRS1972

An improved multiple linear regression and data analysis computer program package

NEWRAP, an improved version of a previous multiple linear regression program called RAPIER, CREDUC, and CRSPLT, allows for a complete regression analysis including cross plots of the independent and dependent variables, correlation coefficients, regression coefficients, analysis of variance tables, t-statistics and their probability levels, rejection of independent variables, plots of residuals against the independent and dependent variables, and a canonical reduction of quadratic response functions useful in optimum seeking experimentation. A major improvement over RAPIER is that all regression calculations are done in double precision arithmetic.

Sidik, S. M.↗

NASA NTRS1972

Exploration of alloy surface and slurry modification to improve oxidation life of fused silicide coated niobium alloys

Edge and surface modifications of niobium alloys were investigated prior to coating with Si-20Cr-20Fe and slurry composition modification for performance in a 1370 C ambient pressure slow cycle test. The best coating obtained was Si-20Cr-20Mn with an average life of 63 cycles, compared to 40 for Si-20Cr-20Fe on FS-85 (100 percent improvement in weight parity life). Edge beading extended the lives of Si-20Cr-20Fe-coated Cb-752 and FS-85 to 57 and 41 cycles respectively (50 and 20 percent improvements in weight parity life respectively). W, Al2O3 and ZrO2(CaO) surface modifications altered coating crack frequency and microstructure and increased life somewhat.

Levine, S. R.↗

NASA NTRS1972

Improved laser ranging accuracy through dynamic threshold compensation

During a polar motion experiment (in which two laser ranging systems on a north-south line simultaneously tracked a satellite to determine motion of the pole), techniques for improving both the range noise and range bias were demonstrated. The corrections to the measured ranges (based on received signal levels relative to a fixed correction that would have been applied if pulse height information was not available) are given. It was shown that even existing long pulse systems (20 to 40 nsec duration) can be improved to the 20 to 30 cm level of precision without major or expensive changes to the system.

Johnson, T. S.↗

NASA NTRS1972

Improvement of synoptic scale moisture and wind field analyses using the Nimbus 4 THIR 6.7 micron observations

The Nimbus 4 temperature-humidity infrared radiometer (THIR) monitors radiation in the 6.5 to 7.2 micron water vapor absorption with a 23 kilometer spatial resolution at the sub-satellite point. Radiation monitored in this spectral region results primarily from emission in the 250 to 500 millibar region of the upper troposphere. The THIR 6.7 micron observations are readily available in photofacsimile imagery form which shows very distinctive patterns associated with spatial variations in atmospheric water vapor. These radiometric observations were combined in several instances with moisture values measured in the upper troposphere by the standard radiosonde network. In each instance, the result is a much more consistent analysis showing increased spatial detail that agrees with the radiometric observations and does not compromise the conventional data. The improved moisture analyses show relatively dry and moist tongues that are very difficult or impossible to infer from the conventional data alone. The patterns in the moisture fields can be tracked over 12 and 24 hour periods. In addition, by keeping in mind the advective properties of the moisture field, success was achieved in improving streamline analyses at the 400 mb level over data sparse regions on a global scale.

Steranko, J.↗

NASA NTRS1972

One hundred ampere-hour nickel-cadmium battery cells of improved design

Nickel cadmium battery cells with 100 ampere hour capacity were developed. The design features, notably extension of the current collector tab to the full width of the battery plate, and the location of the cell terminals on the opposite ends, resulted in a reduction of internal impedance, and improved electrical performance with expected improvement in thermal performance. Tables of data and performance curves are included to support the theoretical considerations.

Kantner, E.↗

NASA NTRS1972

Improvement of a geodetic triangulation through control points established by means of satellite or precision traversing

Whether any significant increment to accuracy could be transferred from a super-control continental net (continental satellite net or super-transcontinental traverse) to the fundamental geodetic net (first-order triangulation) is discussed. This objective was accomplished by evaluating the positional accuracy improvement for a triangulation station, which is near the middle of the investigated geodetic triangulation net, by using various station constraints over its geodetic position. This investigation on a 1858 kilometer long triangulation chain shows that the super-control net can provide a useful constraint to the investigated geodetic triangulation net, and thus can improve it only when the accuracy of super-control net is at least 1 part in 500,000.

Saxena, N. K.↗

NASA NTRS1972

Improvement of Reusable Surface Insulation (RSI) materials

The mullite fiber based hardened compacted fibers (HCF) type of reusable surface insulation was further developed for use in the Space Shuttle Program. Two hundred fifty formulations of fiber mixtures, fillers, binders, and organic processing aids were made using mullite fibers as the basic ingredient. Most of the work was accomplished on 15-lb/cu ft material. It was established that higher density materials are stronger with strength values as high as 250 lb/sq in. in tension. New measurement techniques and equipment were developed for accurate determination of strength and strain to failure. Room temperature to 2300 F stress-strain relationships were made. The room temperature tensile modulus of elasticity is 61,700 lb/sq in. and the strain at failure is 0.165 percent, typically, when measured longitudinally parallel to the long axes of the fibers. Thermal insulating effectiveness was increased 20 percent by reducing the diameter of some of the fibers in the material. Improvements were made in density uniformity and strength uniformity in a block of HCF by mixing improvements and by the use of organic additives. Specifications were established on the materials and processes used in making the insulation.

Blome, J. C.↗

NASA NTRS1972

An investigation to improve selenodetic control on the lunar limb utilizing Apollo 15 trans-earth photography

A study is made using actual metric photography taken by Apollo 15 after the trans earth injection when the spacecraft left the lunar orbit. After measurements on 12 frames were reduced for 11 known control and unknown points on the eastern limb, a least squares adjustment program provided the simultaneous solution for the selected points. The results indicate an improvement in selenodetic control may be achieved over a limited portion of the lunar limb; however, the solution could be further improved by strengthening the geometry of intersecting rays through additional observations of the same area using film from the succeeding Apollo missions.

Riotte, W.↗

NASA NTRS1973

Synthetic sea water - An improved stress corrosion test medium for aluminum alloys

A major problem in evaluating the stress corrosion cracking resistance of aluminum alloys by alternate immersion in 3.5 percent salt (NaCl) water is excessive pitting corrosion. Several methods were examined to eliminate this problem and to find an improved accelerated test medium. These included the addition of chromate inhibitors, surface treatment of specimens, and immersion in synthetic sea water. The results indicate that alternate immersion in synthetic sea water is a very promising stress corrosion test medium. Neither chromate inhibitors nor surface treatment (anodize and alodine) of the aluminum specimens improved the performance of alternate immersion in 3.5 percent salt water sufficiently to be classified as an effective stress corrosion test method.

Humphries, T. S.↗

NASA NTRS1973

Improvements to NASTRAN

Improvements to the operational capabilities of NASTRAN are reported. The improvements include the development and implementation of a number of new finite elements into the existing NASTRAN element library and also the development of a finite element heat transfer analysis capability.

Source record↗

NASA NTRS1973

An improved method for design of expansion-chamber mufflers with application to an operational helicopter

An improved method for the design of expansion-chamber mufflers is described and applied to the task of reducing exhaust noise generated by a helicopter. The method is an improvement of standard transmission-line theory in that it accounts for the effect of the mean exhaust-gas flow on the acoustic-transmission properties of a muffler system, including the termination boundary condition. The method has been computerized, and the computer program includes an optimization procedure that adjusts muffler component lengths to achieve a minimum specified desired transmission loss over a specified frequency range. A printout of the program is included together with a user-oriented description.

Parrott, T. L.↗

NASA NTRS1973

A flight study of the use of direct-lift-control flaps to improve station keeping during in-flight refueling

To investigate the effectiveness of fast-acting flaps as direct-lift-control (DLC) devices on a fighter airplane, the aileron servo systems of an F-100C variable-stability airplane were modified to provide symmetrical actuation of the surfaces. Initial flight tests using DLC indicated that the task of formation flying and, hence, in-flight refueling could be eased by actuating the DLC flaps through the conventional control stick, with the degree of improvement depending on the basic stability of the receiver aircraft. Results of refueling approaches and connections with U.S. Air Force tankers indicated a moderate overall improvement in vertical station-keeping performance (approximately 19 percent) and a sizeable overall decrease in receiver airplane motions and control activity (approximately 40 percent) with DLC.

Mcneill, W. E.↗

NASA NTRS1973

Silica Reusable Surface Insulation Improvement Research

Fiber characterization, fabrication processes, physical properties, and thermal responses are investigated to improve silica reusable surface insulation tiles. Criteria for fiber selection on the basis of chemical composition, shrinkage, and devitrification have been defined and a simple process for fabricating silica surface insulation materials has been developed that produces only 5% shrinkage and no devitrification of tiles at 1533 K in ten hours. Anisotropic tile with improved weak direction strength has been fabricated using conventional molding techniques.

Goldstein, H. E.↗

NASA NTRS1973

Improved Hanle effect measurement technique for fast ions.

An improved averaging technique for use with foil-excited fast ions is applied to a Hanle-effect measurement of the mean life of some fast ions. With improved data analysis, the employed technique is expected to be more precise, as well as experimentally simpler than previously used techniques.

Liu, C. H.↗

NASA NTRS1973

Simulator performance validation and improvement through recorded data.

During the development of two-segment approach procedures instrumentation systems were installed on a 727 flight simulator to monitor a variety of flight parameters. Parameters monitored and data format were designed to be the same as those to be used in later flight tests with line aircraft. Good correlation existed between simulator and aircraft data in many areas. Previously identified areas of poor simulation were checked with quantitative data. The objective data obtained could be used for simulation improvements in areas previously changed primarily by using subjective data obtained from pilots. Areas where similar techniques could improve simulation were identified.

Seay, D. L.↗

NASA NTRS1974

Improved methods for counting bacteria in physiological fluids

Bacterial population detection is based on detection of adenosine triphosphate (ATP), chemical present in all living matter. Amount of ATP in sample, after chemically removing all nonbacterial ATP, is directly related to bacterial population. Sensitivity is improved by concentration step; specificity is improved by lowering pH of solution.

Picciolo, G. L.↗

NASA NTRS1973

Gravity model improvement investigation

This investigation was undertaken to improve the gravity model and hence the ocean geoid. A specific objective is the determination of the gravity field and geoid with a space resolution of approximately 5 deg and a height resolution of the order of five meters. The concept of the investigation is to utilize both GEOS-C altimeter and satellite-to-satellite tracking data to achieve the gravity model improvement. It is also planned to determine the geoid in selected regions with a space resolution of about a degree and a height resolution of the order of a meter or two. The short term objectives include the study of the gravity field in the GEOS-C calibration area outlined by Goddard, Bermuda, Antigua, and Cape Kennedy, and also in the eastern Pacific area which is viewed by ATS-F.

Siry, J. W.↗

NASA NTRS1974

Improvements in estimating proportions of objects from multispectral data

Methods for estimating proportions of objects and materials imaged within the instantaneous field of view of a multispectral sensor were developed further. Improvements in the basic proportion estimation algorithm were devised as well as improved alien object detection procedures. Also, a simplified signature set analysis scheme was introduced for determining the adequacy of signature set geometry for satisfactory proportion estimation. Averaging procedures used in conjunction with the mixtures algorithm were examined theoretically and applied to artificially generated multispectral data. A computationally simpler estimator was considered and found unsatisfactory. Experiments conducted to find a suitable procedure for setting the alien object threshold yielded little definitive result. Mixtures procedures were used on a limited amount of ERTS data to estimate wheat proportion in selected areas. Results were unsatisfactory, partly because of the ill-conditioned nature of the pure signature set.

Horwitz, H. M.↗