The effect of channel errors on data compression.
Channel noise effects on reconstructed data compressed before transmission, defining energy compression ratio figure of merit
Davisson, L. D.↗
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Results for “compressing”
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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Adaptive buffer design for data compression systems.
Data compression system buffer fill control by adaptive compression algorithm aperture
Schwarz, G. R.↗
Compressive buckling of barrel-shaped shells.
Compressive buckling of barrel shaped shells, discussing circumferential tension forces during axial compression to diminish buckling tendency
Becker, H.↗
Compression springs used for vibration isolation
System that employs opposed pairs of compression springs can be totally compressed to provide a ''hard mount'' during component installation and adjustment, and can be released to a free-floating condition for vibration isolation during test.
Norman, R. M.↗
Crossflow effects on compressible turbulent boundary layer over bodies of revolution
Compressible turbulent boundary layer with adverse pressure gradients and crossflow over revolving bodies, integrating numerically three dimensional compressible integral equations
Calarese, W.↗
Source deck compression and update program (CAPS)
Computer program for compressing program source decks and other data coded in Hollerith format is described. Compression of card image record by substitution of special code characters is discussed. Program is written for IBM 360/75/95 Release 19 computer.
Merrill, E. O.↗
Calculation of turbulent boundary layers with heat transfer and pressure gradient utilizing a compressibility transformation. Part 3: Computer program manual
A computer program is described capable of determining the properties of a compressible turbulent boundary layer with pressure gradient and heat transfer. The program treats the two-dimensional problem assuming perfect gas and Crocco integral energy solution. A compressibility transformation is applied to the equation for the conservation of mass and momentum, which relates this flow to a low speed constant property flow with simultaneous mass transfer and pressure gradient. The resulting system of describing equations consists of eight ordinary differential equations which are solved numerically. For Part 1, see N72-12226; for Part 2, see N72-15264.
Schneider, J.↗
Upper bound on compression ratio for run-length encoding.
Run-length encoding is a scheme which has been used to remove redundancy from video signals. Based upon a first-order Markov model of video data, an upper bound on compression ratio is found for run-length encoding. It is shown that at best run-length encoding will give a compression ratio which is approximately 60% of the maximum attainable value. This percentage is fairly independent of the particular picture involved.
Gray, K. G.↗
Channel coding/decoding alternatives for compressed TV data on advanced planetary missions.
The compatibility of channel coding/decoding schemes with a specific TV compressor developed for advanced planetary missions is considered. Under certain conditions, it is shown that compressed data can be transmitted at approximately the same rate as uncompressed data without any loss in quality. Thus, the full gains of data compression can be achieved in real-time transmission.
Rice, R. F.↗
Extended testing of compression distillation.
During the past eight years, the NASA Manned Spacecraft Center has supported the development of an integrated water and waste management system which includes the compression distillation process for recovering useable water from urine, urinal flush water, humidity condensate, commode flush water, and concentrated wash water. This paper describes the design of the compression distillation unit, developed for this system, and the testing performed to demonstrate its reliability and performance. In addition, this paper summarizes the work performed on pretreatment and post-treatment processes, to assure the recovery of sterile potable water from urine and treated urinal flush water.
Bambenek, R. A.↗
Data compression by a decreasing slope-threshold test
Resolution can be obtained at large compression ratios with method for selecting data points for transmission by telemetry in television compressed-data system. Test slope of raw data stream and compare it to symmetric pair of decreasing thresholds. When either threshold is exceeded, data are sampled and transmitted; thresholds are reset, and test begins again.
Kleinrock, L.↗
Compression of helium to high pressures and temperatures using a ballistic piston apparatus
Some preliminary experiments are described which were carried out in a high enthalpy laboratory to investigate the compression of helium, a typical shock-tube driver gas, to very high pressures and temperatures by means of a ballistic piston. The purpose of these measurements was to identify any problem areas in the compression process, to determine the importance of real gas effects duDC 47355s process, and to establish the feasibility of using a ballistic piston apparatus to achieve temperatures in helium in excess of 10,000 K.
Roman, B. P.↗
Theoretical calculation of the compressibility of porous media.
The normalized bulk compressibility of a porous medium is expressed directly in terms of pore strains. The derived expression holds over all porosity and allows for direct substitution of both different pore geometries and pore-pore interactions into the strain term. Pores are assumed to be open. The parent (matrix forming) material is assumed to be homogeneous and isotropic. Pore fluids may be admitted. A simple pore-pore interaction term is introduced. Upper-bound stiffness equations (i.e., equations ignoring pore-pore interactions) are derived for media with oblate spheroidal pores. Effective stress is introduced into the general equation for the normalized bulk compressibility.
Warren, N.↗
Compression of weather charts by the segmented Lynch-Davisson code.
The Lynch-Davisson (L-D) code is shown to be efficient for compressing line-scanned weather charts wherein each line is divided into equal-length segments, and a separate L-D code is generated for each segment. As the number of segments increases, the L-D code length decreases appreciably, thereby simplifying the encoding and decoding operations. However, the accompanying decrease in the overall compression ratio is relatively small.
Lynch, T. J.↗
A modified wall wake velocity profile for turbulent compressible boundary layers.
The law of the wake and the law of the wall in incompressible turbulent boundary layers formulated by Coles (1956) and their use by Mathews et al. (1970) in the development of a wall-wake representation of the velocity profile in a form applicable for isoenergetic compressible boundary layers are extended to a modified wall-wake velocity profile for turbulent compressible boundary layers. The modified wall-wake profile is shown to provide good representations of experimental velocity distributions.
Sun, C.-C.↗
Some design considerations for supersonic cruise mixed compression inlets
A mixed compression inlet designed for supersonic cruise has very demanding requirements for high total pressure recovery and low bleed and cowl drag. However, since the optimum inlet for supersonic cruise performance may have other undesirable characteristics, it is necessary to establish trade-offs between inlet performance and other inlet characteristics. Some of these trade-offs between the amount of internal compression, aerodynamic performance and angle-of-attack tolerance are reviewed. Techniques for analysis of boundary layer control and subsonic diffuser flow are discussed.
Bowditch, D. N.↗
Isentropic compression of fused quartz and liquid hydrogen to several Mbar
Models of the major planets are in part based on the equations of state of very compressible materials such as hydrogen and helium. A technique of isentropically compressing soft material to several Mbar and some preliminary results on fused quartz (silicon dioxide) and liquid hydrogen is described. Quartz was found to be an electrical non-conductor up to 5 Mbar and has a volume of about 0.15 cubic centimeters per gram at that pressure. Liquid hydrogen was found to have a volume of about 1 cm3/g at a pressure of about 2 Mbar. It was not determined if it was transformed into a metal.
Hawke, R. S.↗
Analysis of three-point-bend test for materials with unequal tension and compression properties
An analysis capability is described for the three-point-bend test applicable to materials of linear but unequal tensile and compressive stress-strain relations. The capability consists of numerous equations of simple form and their graphical representation. Procedures are described to examine the local stress concentrations and failure modes initiation. Examples are given to illustrate the usefulness and ease of application of the capability. Comparisons are made with materials which have equal tensile and compressive properties. The results indicate possible underestimates for flexural modulus or strength ranging from 25 to 50 percent greater than values predicted when accounting for unequal properties. The capability can also be used to reduce test data from three-point-bending tests, extract material properties useful in design from these test data, select test specimen dimensions, and size structural members.
Chamis, C. C.↗