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Multiresolutional/Fractal Compression of Still and Moving Pictures

Description: The scope of the present dissertation is a deep lossy compression of still and moving grayscale pictures while maintaining their fidelity, with a specific goal of creating a working prototype of a software system for use in low bandwidth transmission of still satellite imagery and weather briefings with the best preservation of features considered important by the end user.
Date: December 1993
Creator: Kiselyov, Oleg E.
Partner: UNT Libraries

Local Instability of Symmetrical Rectangular Tubes Under Axial Compression

Description: "A chart is presented for the coefficient in the formula for the critical compressive stress at which cross sectional distortion begins in a thin-wall tube of rectangular section symmetrical about its two principal axes. The energy method of Timoshenko was used in the theoretical calculations required for the construction of the chart. The deflection equation used in this method was selected to give good accuracy" (p. 1).
Date: February 1939
Creator: Lundquist, Eugene E.
Partner: UNT Libraries Government Documents Department

Results of Edge-Compression on Stiffened Flat-Sheet Panels of Alclad and Nonclad 14S-T6, 24S-T3, and 75S-T6 Aluminum Alloys

Description: Note presenting an investigation made to augment data previously obtained on the compressive strengths of stiffened flat-sheet panels to include the range where ultimate strengths approach the compressive yield strengths of the materials. The sheet materials tested were alclad and nonclad 14S-T6, 24S-T3, and 75S-T6. Results regarding the typical failure, ultimate strengths, rivet failures, and buckling stresses are provided.
Date: April 1954
Creator: Holt, Marshall
Partner: UNT Libraries Government Documents Department

Critical Stress of Thin-Walled Cylinders in Axial Compression

Description: "Empirical design curves are presented for the critical stress of thin-walled cylinders loaded in axial compression. These curves are plotted in terms of nondimensional parameters of small-deflection theory and are compared with theoretical curves derived for the buckling of cylinders with simply supported and clamped edges. An empirical equation is given for the buckling of cylinders having a length-radius ratio greater than about 0.75" (p. 1).
Date: June 1947
Creator: Batdorf, S. B.; Shildcrout, Murry & Stein, Manuel
Partner: UNT Libraries Government Documents Department

The Effect of Changes in Compression Ratio Upon Engine Performance

Description: "This report is based upon engine tests made at the Bureau of Standards during 1920, 1921, 1922, and 1923. The majority of these tests were of aviation engines and were made in the Altitude Laboratory. For a small portion of the work a single cylinder experimental engine was used. This, however, was operated only at sea-level pressures. The report shows that an increase in break horsepower and a decrease in the pounds of fuel used per brake horsepower hour usually results from an increase in compression ratio" (p. 399).
Date: 1925
Creator: Sparrow, Stanwood W.
Partner: UNT Libraries Government Documents Department

Minimum-Weight Design of Simply Supported Transversely Stiffened Plates Under Compression

Description: Note presenting an investigation of the weight of a simply supported transversely stiffened compression panel subjected to a given buckling load as a function of the stiffener spacing, plate thickness, and the geometry of the stiffener cross section. Results indicate that there are particular combinations of stiffener spacing and plate thickness, dependent on the geometrical properties of the stiffener cross section, for which the panel weight is a minimum.
Date: September 1948
Creator: Gomza, Alexander & Seide, Paul
Partner: UNT Libraries Government Documents Department

Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed

Description: The mutual influences of compression shocks and friction boundary layers were investigated by means of high speed wind tunnels.Schlieren optics provided a clear picture of the flow phenomena and were used for determining the location of the compression shocks, measurement of shock angles, and also for Mach angles. Pressure measurement and humidity measurements were also taken into consideration.Results along with a mathematical model are described.
Date: January 1947
Creator: Ackeret, J.; Feldmann, F. & Rott, N.
Partner: UNT Libraries Government Documents Department

Performance characteristics at Mach numbers to 2.0 of various types of side inlets mounted on fuselage of proposed supersonic airplane 4: rectangular cowl inlets with two-dimensional compression ramps

Description: Report presenting an experimental investigation to determine the performance of side inlets with external compression ramps and rectangular cowls mounted on the fuselage forebody of a proposed supersonic airplane. Results regarding supersonic Mach number range, subsonic Mach number of 0.63, and static or take-off conditions are provided.
Date: October 28, 1952
Creator: Simon, Paul C.
Partner: UNT Libraries Government Documents Department

Tank Tests of a Powered Model of a Compression Plane, NACA Model 171A-2

Description: "The compression plane is intended for operation on or close to the surface of the water, and has a hull with a concave bottom which forms the upper surface of a tunnel into which air is forced under pressure to support part of the load. The results of the tests made in Langley tank no. 1 include values of the horizontal forces, trimming moment, and static pressure in the tunnel for a wide range of loads and speeds and two power conditions, and are presented in the form of curves against speed with load as a parameter. The results are scaled up to 10 times the model size for three conditions at which the model is self-propelled at a steady speed" (p. 1).
Date: July 8, 1948
Creator: Mottard, Elmo J. & Ruggles, Robert D.
Partner: UNT Libraries Government Documents Department

Stresses in and general instability of monocoque cylinders with cutouts 3: calculation of the buckling load of cylinders with symmetric cutout subjected to pure bending

Description: Report presenting a strain-energy theory for the calculation of the buckling load in pure bending of reinforced monocoque cylinders with a symmetric cutout on the compression side and buckle according to the general instability pattern.
Date: May 1947
Creator: Hoff, N. J.; Boley, Bruno A. & Klein, Bertram
Partner: UNT Libraries Government Documents Department

The shearing rigidity of curved panels under compression

Description: Report presenting experiments to determine the shearing rigidity of curved panels under compression, particularly in that region of loading where the panels are in a buckled state. For the preliminary tests four, and for the final test series eight, circular cylinders were built of aluminum alloy sheet. Results regarding the uniformity of compressive strain, buckling of the panels, distribution of shear strain, calculation of the effective shear modulus, shear rigidity versus compressive strain curves, nondimensional shear rigidity curves, and failure of the cylinders are provided.
Date: August 1946
Creator: Hoff, N. J. & Boley, Bruno A.
Partner: UNT Libraries Government Documents Department

Buckling of thin-walled cylinder under axial compression and internal pressure

Description: An investigation was made of a thin-walled cylinder under axial compression and various internal pressures to study the effect of the internal pressure on the compressive buckling stress of the cylinder. A theoretical analysis based on a large-deflection theory was also made. The theoretically predicted increase of compressive buckling stress due to internal pressure agrees fairly well with the experimental results. (author).
Date: 1951
Creator: Lo, Hsu; Crate, Harold & Schwartz, Edward B.
Partner: UNT Libraries Government Documents Department

Condensation of air in supersonic wind tunnels and its effects on flow about models

Description: Report presenting the results of an investigation of condensation phenomena in supersonic wind tunnel. Lower and upper limits for the degree of supersaturation attainable before the onset of condensation of air are discussed. A method is presented for calculating the properties of a stream containing a small fraction of condensed air.
Date: April 1952
Creator: Hansen, C. Frederick & Nothwang, George J.
Partner: UNT Libraries Government Documents Department

Torsion and buckling of open sections

Description: Following an abstract of the well-known theory of torsion in compression, the writers give directions for the practical calculation of the values of C(sub BT) (resistance to flexure and torsion) and i(sub SP(exp 2)), which determine the torsion. The second part treats the experiments in support of the theory of torsion of plain and flanged angle sections.
Date: January 1936
Creator: Wagner, H. & Pretschner, W.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Stiffened Circular Cylinders Subjected to Combined Torsion and Compression

Description: "Five stiffened circular cylinders were tested to failure under various combinations of torsion and compression. The results of the tests are presented in the form of plots of stringer stress against cylinder load and an interaction curve for the strength of stringers that fail by local crippling. A method is given for calculating stiffener stresses in cylinders subjected to combined loads, and a comparison between calculated and experimental stringer stresses is made" (p. 1).
Date: September 1950
Creator: Peterson, James P.
Partner: UNT Libraries Government Documents Department

Interferometric observation of flow about an isentropic (reverse Prandtl-Meyer streamline) compression wedge at Mach 3.0

Description: Report presenting an interferometric study of the flow over a two-dimensional isentropic compression surface at a Mach number of 3.0. The flow field was essentially that of a strong-branch-shock configuration resulting from a surface flow turning that corresponded to an empirical limiting value of free-stream normal-shock pressure rise.
Date: March 28, 1955
Creator: Connors, James F.; Woollett, Richard R. & Blue, Robert E.
Partner: UNT Libraries Government Documents Department

Performance tests of wire strain gages 2: calibration factors in compression

Description: Report presenting the results of calibrations in axial compression over the strain range 0 to 0.0021 for 15 types of single element multistrand wire strain gages. The majority of gages showed significant differences between the calibration factors for strain increasing and strain decreasing. The majority of the gages were found to have slightly lower factors in compression than in tension.
Date: September 1945
Creator: Campbell, William R.
Partner: UNT Libraries Government Documents Department

The apparent width of the plate in compression

Description: This report discusses an investigation that treats the load capacity of a rectangular plate stressed in compression on one direction (x) beyond the buckling limit and the plate is rotatable (i.e., free from moments) supported at all four sides by bending-resistant beams.
Date: July 1937
Creator: Marguerre, Karl
Partner: UNT Libraries Government Documents Department

Vacuum-Freezing Vapor-Compression Process: Evaluation on Brackish Water

Description: From Abstract: "The Vacuum-Freezing Vapor-Compression (VFVC) Process was evaluated on high salinity brackish water during the period from February 1968 through December 1969 by Colt Industries Inc., under O.S.W. Contract No. 14-01-0001-967 at Roswell, New Mexico. The 15,000 gpd VFVC test plant is mounted on a mobile trailer which was built by Colt Industries Inc. in their factory at Beloit, Wisconsin. Prior to operation at Roswell, the plant was operated at Wrightsville Beach, North Carolina to check out the system and to operate the trailer on sea water." Process Description: "A simplified diagram, Figure 2, shows both the essential components of the process and flow paths of the various streams in the system. Typical heat and mass balances are shown on Figures 3 and 4."
Date: March 1970
Creator: Jhawar, M. M. & Fraser, J. H.
Partner: UNT Libraries Government Documents Department

A study of a symmetrical, circular, internal, compression inlet

Description: From Summary: "A preliminary experimental study of symmetrical, circular, internal compression inlets has shown that they attain pressure recovery equal to that measured by conical nose inlets at Mach numbers up to about 2.3. This pressure recovery was obtained with configurations having essentially zero pressure drag of the external surfaces."
Date: February 13, 1956
Creator: Mossman, Emmet A. & Pfyl, Frank A.
Partner: UNT Libraries Government Documents Department

Charts for the Rapid Calculation of the Work Required to Compress Dry Air

Description: Report presenting a study of accurate values of the specific heat for dry air applied to the calculation of work required to compress dry air. Two charts are provided that allow the work of compression to be determined from the initial temperature, overall pressure ratio, and either the compression exponent or adiabatic efficiency of the compressor.
Date: April 1946
Creator: Benser, William A.; Wilcox, Ward W. & Voit, Charles H.
Partner: UNT Libraries Government Documents Department

Compression Tests of Six Curved Paper-Base Plastic Panels With Outward-Acting Normal Pressure

Description: Report presenting results of compression tests of six paper-base plastic panels with outward-acting normal pressure. All panels failed by separation of the skin, either from the rib or from the stiffeners. Results regarding the introduction of air pressure and types of failures encountered are provided.
Date: September 1944
Creator: Schuette, Evan H.; Rafel, Norman & Dobrowski, Charles V.
Partner: UNT Libraries Government Documents Department

Compressive-Strength Comparisons of Panels Having Aluminum-Alloy Sheet and Stiffeners With Panels Having Magnesium-Alloy Sheet and Aluminum Alloy Stiffeners

Description: Report presenting comparisons of 24S-T aluminum-alloy flat compression panels with longitudinal Z-section stiffeners and panels with flat FS-1E magnesium-alloy sheet and longitudinal 24S-T aluminum-alloy Z-section stiffeners. The use of the composite magnesium-alloy, aluminum-alloy construction permits wider stiffener spacing with little to not loss in structural efficiency or stress for local buckling. Results regarding stiffener spacing, proportions, and consideration of the different material constructions are provided.
Date: April 1947
Creator: Dow, Norris F.; Hickman, William A. & McCracken, Howard L.
Partner: UNT Libraries Government Documents Department