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Description: jectives, the accomplishments, and a summary of the work outstanding. The obtectives of the experimental and analytical studies were to investigate and reach an understanding of the kinetic behavior of aqueous homogeneous reactors. Information produced by the program, experiments on the spherical core, capsule experiments, and the remaining work schedule are discussed. (W.D.M.)
Date: January 28, 1959
Creator: Flora, J. W.
Partner: UNT Libraries Government Documents Department

Motion of Spheres in Still Fluids

Description: "The behavior of a liquid or gaseous medium, in which a solid body can move freely under the action of a force of constant magnitude and direction, is yet little known. Only in connection with a few special problems, which belong in this field, have experiments been tried and these chiefly concern technically important cases. The behavior of the simplest shaped bodies has as yet been scarcely investigated at all" (p. 1).
Date: April 1924
Creator: Hirsch, P.
Partner: UNT Libraries Government Documents Department

Turbulence and Mechanism of Resistance on Spheres and Cylinders

Description: The nature of turbulent flow through pipes and around obstacles is analyzed and illustrated by photographs of turbulence on screens and straighteners. It is shown that the reversal of flow and of the resistance law on spheres is not explainable by Prandtl's turbulence in the boundary layer. The investigation of the analogous phenomena on the cylinder yields a reversal of the total field of flow.
Date: January 1932
Creator: Ahlborn, F.
Partner: UNT Libraries Government Documents Department

Recent Researches on the Air Resistance of Spheres

Description: The following conclusions on air resistance of spheres are drawn: 1) disturbances in front of the sphere and even single fine wires affect the critical Reynolds Number; 2) disturbances around the sphere increased the drag of the sphere without martially affecting the value of the Reynolds Number(sub crith); 3) great disturbances of the boundary layer of the sphere likewise change R.N.(sub crith); 4) turbulence of the approaching air stream lowers critical R.N.
Date: August 1928
Creator: Flachsbart, O.
Partner: UNT Libraries Government Documents Department

Sphere Drag Tests in the Variable Density Wind Tunnel

Description: The air forces on a twenty-centimeter sphere were measured after it had been rebuilt as an open throat type. The results from tests made at widely different densities and airspeeds and also on a smaller sphere are given. The conclusions are that approximately the same drag coefficient is obtained at a given value of the Reynolds number irrespective of what combination of the variables is used to obtain that value and that the turbulence of the air stream at the test section, as measured by the critical Reynolds number of a sphere, is less for the new tunnel than for the old one.
Date: August 1929
Creator: Jacobs, Eastman N.
Partner: UNT Libraries Government Documents Department

Preliminary Tests in the Supersonic Sphere

Description: "This report presents preliminary data obtained in the Langley supersonic sphere. The supersonic sphere is essentially a whirling mechanism enclosed in a steel shell which can be filled with either air or Freon gas. The test models for two-dimensional study are of propeller form having the same plan form and diameter but varying only in the airfoil shape and thickness ratio. Torque coefficients for the 16-006, 65-110, and the 15 percent thick ellipse models are presented, as well as pressure distributions on a circular-arc supersonic airfoil section having a maximum thickness of 10 percent chord at the 1/3-chord position" (p. 1).
Date: January 20, 1948
Creator: Baker, John E.
Partner: UNT Libraries Government Documents Department

The Resistance to the Steady Motion of Small Spheres in Fluids

Description: "There seems to be little reliable information conveniently available as to the resistance encountered by small spheres moving steadily at moderate speeds in fluids. The present paper, while presenting nothing new in the way of either theory or data, has three objects: first to show that published data are sufficient to furnish approximate information; second to present this information in form convenient for computation; and, third to indicate where further research is needed" (p. 1).
Date: February 1926
Creator: Castleman, R. A.
Partner: UNT Libraries Government Documents Department

Theoretical Distribution of Laminar-Boundary-Layer Thickness, Boundary-Layer Reynolds Number and Stability Limit, and Roughness Reynolds Number for a Sphere and Disk in Incompressible Flow

Description: Note presenting the calculation of the laminar-boundary-layer thickness, the boundary-layer Reynolds number and minimum critical Reynolds number, and the roughness Reynolds numbers by an approximate method for a sphere and disk in the supercritical Reynolds number region. The calculations indicate that the boundary layer at the stagnation point of a sphere is much thicker than that of an airfoil and the boundary-layer thickness increases very slowly with an increase in distance from the stagnation point.
Date: September 1958
Creator: Tetervin, Neal
Partner: UNT Libraries Government Documents Department

Ball lens reflections by direct solution of Maxwell`s equations

Description: Ball lenses are important for many applications. For example, ball lenses can be used to match the mode of a laser diode (LD) to a single mode fiber (SMF), essential for low-loss, high bit rate communication systems. Modeling the propagation of LD light through a ball lens presents a challenge due to the large angular divergence of the LD field (typically > 20{degrees} HWHM) and the subsequent significant effect of spherical aberration. Accurately calculating the reflected power is also difficult, but essential, since reflections as small as {minus}30 dB can destabilize the LID. A full-wave analysis of this system using, e.g., a finite-difference time-domain method is not practical because of the size of the ball lens, typically hundreds of wavelengths in diameter. Approximate scalar methods can give good results in some cases, but fail to calculate reflected power and miss polarization effects entirely. The authors` approach exploits the fact that the scattering of an arbitrary electromagnetic beam from a sphere is an exactly solvable problem. The scattering of a plane wave from a sphere is a classical problem which was solved by Mie in 1908. More recently, various workers have considered the scattering of a Gaussian beam from a sphere and its numerical implementation for other applications. To the authors knowledge, this is the first time this approach has been applied to a problem in optical design. They are able to calculate reflection and transmission accurately with modest computational effort.
Date: February 15, 1995
Creator: Ratowsky, R.P.; Deri, R.J. & Kallman, J.S.
Partner: UNT Libraries Government Documents Department

An IBM-704 Code for a Harmonics Method Applied to Two-Region Spherical Reactors

Description: An IBM-704 computer code for the harmonics method of criticality calculation for two-region spherical reactors is described. In the harmonics method, the criticality condition corresponds to the vanishing of a certain infiniteorder determinant; in practice, this condition is replaced by equating a finite-order approximating determinant to zero. By hand, the calculations can be performed conveniently only for second-order approximating determinants. The approximating determinant with the described code is customarily of the seventh order. Losses of significant figures prevented the use of larger determinants. The machine running time per case is generally about 30 sec. (auth)
Date: March 15, 1960
Creator: Chalkley, R.; Nestor, C. W., Jr. & Tobias, M. L.
Partner: UNT Libraries Government Documents Department


Description: Thc objective of the project was to determine the velocity-time and distance-time histories of anthropomorphic dummies and equivalent spheres (idealized models having an acceleration coefficient alpha equal to that of the dummy) displaced by blast winds. The dummies and spheres were located at stations within regions of about 5 and 7 psi overpressures. The technique used for recording the movement of these objects was phototriangulation. Analysis of the films obtained gave the ond shot the field of veiw was obscured by smoke (perhaps dust too) before any motion could be recorded by the cameras. In one phase of the experiment, equivalent spheres were caught in flight at near predicted maximum velocity by missile traps. The depth of sphere penetration in the calibrated capture medium was then used to compute the sphere velocity. (auth)
Date: February 1, 1959
Creator: Taborelli, R.V.; Bowen, I.G. & Fletcher, E.R.
Partner: UNT Libraries Government Documents Department

Resorcinol-formaldehyde and carbon aerogel microspheres

Description: Aerogels are a unique class of materials possessing an open-cell structure with ultrafine cells/pores (<100nm), high surface area (400--1100 m{sup 2}/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10nm. Although monolithic aerogels are ideal candidates for many applications (e.g. transparent window insulation), current processing methods have limited their introduction into the commercial marketplace. Our research focuses on the formation of resorcinol-formaldehyde (RF) aerogel microspheres which offer an attractive alternative to monolith production. An inverse emulsion polymerization is used to produce these spherical gel particles which undergo solvent exchange followed by supercritical drying with carbon dioxide. This process yields aerogel microspheres (10--80{mu} diameter) which can be used as loosely packed powders, compression molded into near-net shapes using a polymer binder, or used as additives in conventional foaming operations to produce new aerogel composites with superior thermal properties. The emulsification procedure, thermal characterization, mechanical properties, and potential applications of RF aerogel microspheres will be discussed.
Date: April 1996
Creator: Alviso, C. T.; Pekela, R. W.; Gross, J.; Lu, X.; Caps, R. & Fricke, J
Partner: UNT Libraries Government Documents Department

Final technical report

Description: Granular flows of nearly elastic, identical spheres down bumpy inclines are described. A numerical technique is developed to overcome the difficulties associated with the ill-defined `tops` of these flows.
Date: August 1, 1996
Creator: Richman, M.
Partner: UNT Libraries Government Documents Department

Prompt neutron decay for an unreflected and unmoderated uranium (HEU) metal sphere

Description: Prompt neutron decay constants were measured for a delayed critical, unmoderated and unreflected U metal sphere at the Oak Ridge Critical Experiments Facility. Prompt neutron decay constant was 1.1095{+-}0.0013 {mu}s{sup -1}. This can be used to verify calculational methods, both deterministic and Monte Carlo neutron transport methods. This value is in agreement with the value from GODIVA I data corrected for effects of support structure (1.10{+-}0.01 {mu}s{sup -1}) but has a much smaller error as a result of the large number (167) of the measurements here and the high degree of sphericity of the sphere.
Date: August 1, 1996
Creator: Mihalczo, J.T.
Partner: UNT Libraries Government Documents Department