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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

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

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

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 of corrugated-sheet-stiffened panels for consolidated XB-36 airplane

Description: From Summary: "Compression tests were made of 63 panels stiffened with corrugated sheet. The specimens were constructed from artificially aged alclad 24S-T aluminum alloy with minimum guaranteed yield strengths of 57 and 48 kips per square inch for the flat- and corrugated-sheet materials, respectively. Results of the tests are presented in charts which show the average stresses at the maximum load and at buckling of the sheet."
Date: January 1944
Creator: Weinberger, Robert A.; Sperry, William C. & Dobrowski, Charles V.
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

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

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

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

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

Higher Compression from the Burrows-Wheeler Transform with New Algorithms for the List Update Problem

Description: Burrows-Wheeler compression is a three stage process in which the data is transformed with the Burrows-Wheeler Transform, then transformed with Move-To-Front, and finally encoded with an entropy coder. Move-To-Front, Transpose, and Frequency Count are some of the many algorithms used on the List Update problem. In 1985, Competitive Analysis first showed the superiority of Move-To-Front over Transpose and Frequency Count for the List Update problem with arbitrary data. Earlier studies due to Bitner assumed independent identically distributed data, and showed that while Move-To-Front adapts to a distribution faster, incurring less overwork, the asymptotic costs of Frequency Count and Transpose are less. The improvements to Burrows-Wheeler compression this work covers are increases in the amount, not speed, of compression. Best x of 2x-1 is a new family of algorithms created to improve on Move-To-Front's processing of the output of the Burrows-Wheeler Transform which is like piecewise independent identically distributed data. Other algorithms for both the middle stage of Burrows-Wheeler compression and the List Update problem for which overwork, asymptotic cost, and competitive ratios are also analyzed are several variations of Move One From Front and part of the randomized algorithm Timestamp. The Best x of 2x - 1 family includes Move-To-Front, the part of Timestamp of interest, and Frequency Count. Lastly, a greedy choosing scheme, Snake, switches back and forth as the amount of compression that two List Update algorithms achieves fluctuates, to increase overall compression. The Burrows-Wheeler Transform is based on sorting of contexts. The other improvements are better sorting orders, such as “aeioubcdf...” instead of standard alphabetical “abcdefghi...” on English text data, and an algorithm for computing orders for any data, and Gray code sorting instead of standard sorting. Both techniques lessen the overwork incurred by whatever List Update algorithms are used by reducing the difference between adjacent sorted ...
Date: August 2001
Creator: Chapin, Brenton
Partner: UNT Libraries

Microbunching studies for SPARX photoinjector

Description: The SPARX X-FEL accelerator will be the first FEL facility to operate with a hybrid (RF plus magnetic chicane) compression scheme. Numerical studies of propagation of beam density modulations stemming from photogun laser, through the photoinjector operating under velocity bunching conditions have been carried out. A semi-analytical model for the linear gain in a RF compressor is also being developed and some preliminary results are presented.
Date: May 1, 2009
Creator: Ronsivalle, C.; Ferrario, M.; Migliorati, M. & Venturini, M.
Partner: UNT Libraries Government Documents Department

The interaction of boundary layer and compression shock and its effect upon airfoil pressure distributions

Description: Report presenting an investigation of the mechanism of interaction of compression shock with boundary layer. Shockless pressure distributions at supercritical Mach numbers were found to be accounted for by a marked thickening of the boundary layer for some distance ahead of a shock wave.
Date: April 10, 1947
Creator: Allen, H. Julian; Heaslet, Max A. & Nitzberg, Gerald E.
Partner: UNT Libraries Government Documents Department

Effect of Compression Ratio, Pressure, Temperature, and Humidity on Power

Description: Among other factors which affect the horsepower of an airplane engine are the atmospheric pressure, and consequently the altitude at which the engine is working, and the compression ratio, or cylinder volume divided by clearance volume. The tests upon which this report is based were selected from a large number of runs made during the intercomparison of various gasolines to determine the variation of horsepower with altitude at three different compression ratios. The test results and conclusions are presented in this report.
Date: 1919
Creator: Dickinson, H. C.; James, W. S.; Anderson, G. V. & Brinkerhoff, V. W.
Partner: UNT Libraries Government Documents Department

Effect of rivet and spot-weld spacing on the strength of axially loaded sheet-stringer panels of 24S-T aluminum alloy

Description: Report presenting testing of eighteen 24S-T aluminum alloy sheet-stringer panels in end compression under carefully controlled edge conditions. Results regarding the strains, deflections, failure, and buckling of the sheet are provided.
Date: August 1942
Creator: Levy, Samuel; McPherson, Albert E. & Ramberg, Walter
Partner: UNT Libraries Government Documents Department

Survey of supersonic inlets for high Mach number applications

Description: Report presenting an assessment of various inlet design philosophies assessed on the basis of recent experimental results at Mach numbers up to 5. The basic compression systems are compared for Mach 4.0 turbojet and hypersonic-cruise ramjet engines.The best-suited inlet for the Mach 4.0 turbojet engine is the combined external-plus-internal compression.
Date: April 1, 1958
Creator: Connors, James F. & Allen, John L.
Partner: UNT Libraries Government Documents Department

Compression and Diffusion: A Joint Approach to Detect Complexity

Description: Article discussing a joint approach to detect complexity by combining the Compression Algorithm Sensitive To Regularity (CASToRe) and Complex Analysis of Sequences via Scaling AND Randomness Assessment (CASSANDRA) procedures.
Date: February 2003
Creator: Allegrini, Paolo; Benci, V. (Vieri); Grigolini, Paolo; Hamilton, P.; Ignaccolo, Massimiliano; Menconi, Giulia et al.
Partner: UNT College of Arts and Sciences

Effects of Processing Techniques on Mechanical Properties of Selected Polymers

Description: The mechanical properties of a polymer represent the critical characteristics to be considered when determining the applications for it. The same polymer processed with different methods can exhibit different mechanical properties. The purpose of this study is to investigate the difference in mechanical properties of the selected polymers caused by different processing techniques and conditions. Three polymers were studied, including low density polyethylene (LDPE), polypropylene (PP), and NEXPRENE® 1287A. Samples were processed with injection molding and compression molding under different processing condition. Tensile and DMA tests were performed on these samples. The acquired data of strain at break from the tensile tests and storage modulus from the DMA were utilized to calculate brittleness. Calculated brittleness values were used to perform analysis of variance (ANOVA) to investigate the statistical significance of the processing technique and condition. It was found that different processing techniques affect the brittleness significantly. The processing technique is the major factor affecting brittleness of PP and NEXPRENE, and the processing temperature is the major factor affecting brittleness of LDPE.
Date: May 2013
Creator: Dong, Yao
Partner: UNT Libraries