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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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Technical report on the effects of sterilization on the energy-dissipating properties of balsa wood is given. Sterilization by ethylene oxide plus heat enhances the average specific energy of balsa while plastic impregnation followed by irradiation-induced polymerization does not.
Impact properties of balsa wood in sterilized, dry and humid conditions
Inelastic scattering cross sections calculated, comparing results for various nuclear states expressed as Wood-Saxon radial and harmonic oscillator functions
Jet aircraft noise attenuation characteristics of wood-sided and brick-veneered frame houses
Hartree-Fock method to study doubly even nuclei in 2s-1d shell, generating basis functions by Wood-Saxon well
Phenolic aldehydes generated from lignin in fossil woods and carbonaceous sediments by oxidative degradation
Investigating short-range behavior of wave function by comparing projected Hartree-Fock spectra using basis functions having harmonic oscillator and Wood-Saxon radial dependence
Projected Hartree-Fock energy spectra using basis wave functions with harmonic oscillator and Wood-Saxon radial dependence
A combined analytical and experimental study of wood planer noise is made and the results applied to the development of practical noise control techniques. The dominant mechanisms of sound generation are identified and an analysis is presented which accurately predicts the governing levels of noise emission. Planing operations in which the length of the board is much greater than the width are considered. The dominant source of planer noise is identified as the board being surfaced, which is set into vibration by the impact of cutterhead knives. This is determined from studies made both in the laboratory and in the field concerning the effect of board width on the resulting noise, which indicate a six decibel increase in noise level for each doubling of board width. The theoretical development of a model for board vibration defines the vibrational field set up in the board and serves as a guide for cutterhead redesign.
Hot pressed wood panels made with modified novolak resins have burnthrough time of 450 s as compared to 280 s for products using conventional novolak resins. Incorporation of inorganic filler reduces flame spread index of panels from more than 200 to 60 or 70.
A joint study has been conducted by NASA and Army installations collocated in a dense forest in southwestern Mississippi in order to determine the technical and economic feasibility of using wood waste as a renewable energy source. The study has shown that, with proper forest management, the timber on government lands could eventually support the total energy requirements of 832 billion Btu/yr. Analysis of the current conversion technologies indicates that the direct combustion spreader stoker approach is the best demonstrated technology for this specific application. The economics of the individual powerplants reveal them as attractive alternatives to fossil fueled plants. Environmental aspects are also discussed.
Heat conduction throughout the blade and the distribution of thermal stresses caused by the temperature distribution were determined for a laminated wood wind turbine blade in both the horizontal and vertical positions. Results show that blade cracking is not due to thermal stresses induced by insulation. A method and practical example of thermal stress analysis for an engineering body of orthotropic materials is presented.
The thermal-stress induced by solar insolation on a wood composite blade of a Mod-OA wind turbine was investigated. The temperature distribution throughout the blade (a heat conduction problem) was analyzed and the thermal-stress distribution of the blades caused by the temperature distribution (a thermal-stress analysis problem) was then determined. The computer programs used for both problems are included along with output examples.
A thermal-stress analysis of a wind turbine blade made of wood composite material is reported. First, the governing partial differential equation on heat conduction is derived, then, a finite element procedure using variational approach is developed for the solution of the governing equation. Thus, the temperature distribution throughout the blade is determined. Next, based on the temperature distribution, a finite element procedure using potential energy approach is applied to determine the thermal-stress distribution. A set of results is obtained through the use of a computer, which is considered to be satisfactory. All computer programs are contained in the report.
The premature fatigue failure of a laminated wood/epoxy test beam containing a cross section finger joint was the subject of a multi-disciplinary investigation. The primary objectives were to identify the failure mechanisms which occurred during the finger joint test and to provide avenues for general improvements in the design and fabrication of adhesive joints in laminated wood structures.
A standard methodology for thematic mapping of natural vegetation using remotely sensed imagery and digital image processing was modified to account for the spatial and spectral properties of semi-arid landscapes, and tested in study areas in the Sahelian and Sudanian zones, Mali. A principal components transformation of registered wet and dry season Landsat TM images produced a set of synthetic spectral channels differentiating vegetation cover between seasons, and allowed areas with annual grass growth to be distinguished from areas with woody cover. The transformed data were statistically clustered and clusters were assigned to vegetation type and density categories. In a separate step, the images were manually interpreted to differentiate broad soil classes. Four statistics were compared to evaluate the accuracy of the maps based on sample points from air photos. For the relatively detailed categories initially defined, map accuracies were substandard; however, when vegetation density classes were aggregated, overall accuracy was around 90 percent, and class accuracy was greater than 80 percent for most classes. This method is suitable for stratification and inventory of woody biomass at a regional scale in semi-arid woodland and wooded grassland.
This report describes briefly a series of experiments made at the Forest Products Laboratory, Madison, Wisconsin, to determine the comparative moisture resistance of linseed oil, impregnation treatments, condensation varnishes, oil varnishes, enamels, cellulose varnishes, rubber, electroplated and sprayed metal coatings, and metal-leaf coatings when applied to wood. All coatings except rubber and electroplated metal coatings, which were not developed sufficiently to make them practical, admitted moisture in varying degrees. The most effective and most practical coating was found to be that of aluminum leaf.
The investigation described in this report was made primarily to afford a comparison between propeller tests in the new propeller research tunnel and flight tests and small model tests on propellers. Three wood propellers which had been previously tested in flight on a VE-7 airplane, and of which models had also been tested in a wind tunnel, were tested again on a VE-7 airplane in the propeller research tunnel. The results of these tests are in fair agreement with those of the flight and model tests. Tests were also made with the tail surfaces removed, and with both the wing and tail surfaces removed. It was found that the effect of the tail surfaces on the propeller characteristics was negligible, but that the wings reduced the maximum propulsive efficiency about 5 percent. (author)