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49 results on '"Francavilla, T. L."'

24. Microstructural and superconductive studies of Ag-YBa2Cu3O7−x composites

Author

Khan, H. R., Francavilla, T. L., Hein, R. A., Pande, C. S., Qadri, S. B., Soulen, R. J., and Wolf, S. A.

Abstract

Composites of Ag-YBa2Cu3O7-x were synthesized and carefully characterized for crystal structure and microstructure by X-ray diffraction, optical microscopy, SEM, TEM, and EDAX techniques in order to investigate the effect of Ag additions on the superconducting properties of 123 compounds. The a.c. susceptibility data show thatTc (onset) of 123+Ag composites vary between 90.2 and 91.8 K. TheJc values we measured for 123 material without silver were in the range of earlier reported values for the pure 123 material. Whereas there is a relatively small increase in the critical current for the YBCO/Ag2O ratio of 3, the variation of the grain size of the composites shows that theseJc changes are due to slight variations in the grain size rather than any dramatic effect of Ag inclusions as speculated earlier.

Published
1990
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27. Superconducting Switch Program

Author

NAVAL RESEARCH LAB WASHINGTON DC, Francavilla, T. L., Wolf, S. A., Gubser, D. U., NAVAL RESEARCH LAB WASHINGTON DC, Francavilla, T. L., Wolf, S. A., and Gubser, D. U.

Abstract

This is the final report of work done to study the feasibility of a superconducting opening switch. This phase of the investigation considers the following: 1) The achievement of critical current densities of over 10 to the 7th power A/sq cm in NbN. 2) Determination of the power required to operate a superconducting switch. 3) Utilization of materials other than NbN in such a switch.

Published
1989

28. Critical Current Density and Transition Temperature Measurements of Y-Ba-Cu-O Rods

Author

NAVAL RESEARCH LAB WASHINGTON DC, Francavilla, T. L., Candela, G. A., Soulen, Jr, R. J., NAVAL RESEARCH LAB WASHINGTON DC, Francavilla, T. L., Candela, G. A., and Soulen, Jr, R. J.

Abstract

Measurements were made on the superconducting properties of cylindrical Y-Ba-Cu-O rods prepared by ICI Americas Inc. The transition temperature was determined from measurements of ac susceptibility as a function of temperature. The critical current density at 77K was determined by measuring the voltage as a function of current using four terminal transport measurements, in magnetic fields of different intensities.

Published
1989

29. ONR-NRL Superconducting Materials Symposium. A Forecast.

Author

NAVAL RESEARCH LAB WASHINGTON D C, Francavilla,T L, Gubser,D U, Wolf,S A, NAVAL RESEARCH LAB WASHINGTON D C, Francavilla,T L, Gubser,D U, and Wolf,S A

Abstract

Partial Contents: Ternary Compounds; Granular Superconductors; Superconductivity in (SN)x and its Halogen Derivative (SNBr0.4)x; Studies of cuCl at Elevated Pressures; Superconducting Properties of Hydride Systems; Thin Film Superconducting Materials Research; Synthesis of Superconducting Nb3Si using High Pressures; Synthesis of Unstable A-15 Compounds by Epitaxial Recrystallization of Ion Implanted Layers; and Sputtering of Nb3Si.

Published
1979

30. COMPUTER PROGRAM FOR THE NRL SATELLITE POSITION DISPLAY

Author

NAVAL RESEARCH LAB WASHINGTON D C, Orsino,R. J., Francavilla,T. L., NAVAL RESEARCH LAB WASHINGTON D C, Orsino,R. J., and Francavilla,T. L.

Abstract

A computer driven satellite display has recently been developed and evaluated at the Naval Research Laboratory. This equipment, designated as the NRL Satellite position Prediction And Display (SPAD), provides a considerable amount of display control versatility. Up to eleven satellites can be selected either individually or by category from a repertoire of 88 satellites. These selected satellites are then updated and displayed in either real time or at an accelerated time. Several display modes are available at an operator's command, namely, world map, rectangular expanded mode, and polar expanded mode. A commercial equivalent of the AN/UYK-1 computer was used in the research version of SPAD. Since the program was written in a language peculiar to this machine, the program listings and codings are omitted from the present report. However, included in this report are the complete set of computer program flow diagrams and a brief description of the interrupt service routines along with their corresponding subroutines. Characteristics of the AN/UYK-1 computer, operator control panel provisions and possible future program modifications are discussed. The contents of this report should be a sufficient indication of the program philosophy. This philosophy, with appropriate minor changes, could be implemented by any suitable language. (Author), See also AD-639 692, AD-643 561.

Published
1966

32. Type I odontoid fractures

Author

Francavilla, T L, primary, Melisi, J, additional, Chappell, E T, additional, McCrary, M, additional, Pait, T G, additional, and Mark, A S, additional

Published
1989
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46. Magnetic Field Studies of the La2-xMxCuO4and Ba2Y1Cu3O7High TcSuperconductors

Author

Fuller, W. W., Osofsky, M. S., Toth, L. E., Qadri, S. B., Lawrence, S. H., Hein, R. A., Gubser, D. U., Francavilla, T. L., and Wolf, S. A.

Abstract

We have prepared and characterized high Tcsingle phase samples of La2-xMxCuO4(where M = Sr, Ba, or Ca and x = 0.1, 0.2, or 0.3) and Ba2Y1Cu3O7. We report on the dc susceptibility, magnetization, and magnetoresistance. We have extracted many of the critical superconducting and normal state parameters from the data.

Published
1987
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48. Neurosurgery in paradise.

Author

Francavilla TL

Subjects
Florida, Humans, Neurosurgery, Practice Patterns, Physicians', Professional Practice Location
Published
1995

49. MR imaging of thoracic disk herniations.

Author

Francavilla TL, Powers A, Dina T, and Rizzoli HV

Subjects
Adult, Female, Humans, Intervertebral Disc diagnostic imaging, Intervertebral Disc surgery, Intervertebral Disc Displacement surgery, Middle Aged, Myelography, Thoracic Vertebrae diagnostic imaging, Thoracic Vertebrae pathology, Thoracic Vertebrae surgery, Tomography, X-Ray Computed, Intervertebral Disc pathology, Intervertebral Disc Displacement diagnosis, Magnetic Resonance Imaging
Abstract

Magnetic resonance (MR) is of value in imaging intervertebral disk disease. We present the MR findings in two patients with thoracic disk herniations who required surgical intervention. The advantages of MR over CT myelography are ease of obtaining sagittal sections, rapid assessment of the entire thoracic spine, and a high rate of patient acceptance related to the noninvasive nature of MR and lack of morbidity and complications. For these reasons, we currently rely, almost exclusively, on MR for evaluating thoracic disk disease.

Published
1987
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