The scattering of the sound of a jet engine by an airplane fuselage is modelled by solving the axially symmetric Helmholtz equation exterior to a long thin ellipsoid. The integral equation method based on the single l...
The scattering of the sound of a jet engine by an airplane fuselage is modelled by solving the axially symmetric Helmholtz equation exterior to a long thin ellipsoid. The integral equation method based on the single layer potential formulation is used. A family of coordinate systems on the body is introduced and an algorithm is presented to determine the optimal co-ordinate system. Numerical results verify that the optimal choict enables the solution to be computed with a grid that is coarse relative to the wavelength.
The farfield acoustic scattering by a prolate spheroid with axial point sources near the tip of the body was measured. Data were taken for ka between 10 and 160, where a is the semimajor axis of the spheroid. Comparis...
The farfield acoustic scattering by a prolate spheroid with axial point sources near the tip of the body was measured. Data were taken for ka between 10 and 160, where a is the semimajor axis of the spheroid. Comparisons were made with numerical results obtained by an integral equation based on the simple‐source method, with appropriate coordinate stretching introduced to permit high‐frequency solutions with a minimal number of grid points. Theory and experiment agree within experimental error except for the highest frequencies in the shadow region, where very rapid changes in pressure make precise measurements difficult. The results show that for frequencies of aeroacoustic interest, the scattered field is very large and cannot be ignored.
Recently two dissection algorithms (one-way and incomplete nested dissection) have been developed for solving the sparse positive definite linear systems arising from n by n grid problems. Concurrently, vector compute...
The purpose of this paper is to investigate the solution of the fourth order boundary value problem μz= — α(s)μsssswith boundary conditions μs(0) = μs(a) — μsss(0) = μsss(a) = 0, where α(s) is square integra...
The purpose of this paper is to investigate the solution of the fourth order boundary value problem μz= — α(s)μsssswith boundary conditions μs(0) = μs(a) — μsss(0) = μsss(a) = 0, where α(s) is square integrable on 0 0, and 0 < z < ∞. This problem arises in certain areas of fluid dynamics. If [0, a] is divided into equal intervals of length h such that 0 — s1 < s2 <… < sn-1
The problem of solving tridmgonal linear systems on vector computers is considered. In particular, implementations of several direct and lterative methods are given for the Control Data Corporatlon STAR-100 computer. ...
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Atomic Hartree‐Fock self‐consistent‐field energy‐optimized even‐tempered Gaussian bases are obtained for hydrogen, helium and all first‐row atoms in their ground states. In comparison with Huzinaga‐type bases t...
Strong electron emission is reported from patterned thin films of tin-indium oxide and preliminary studies of this phenomenon are presented. The pattern, etched in the sputtered films using standard photolithographic ...
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Strong electron emission is reported from patterned thin films of tin-indium oxide and preliminary studies of this phenomenon are presented. The pattern, etched in the sputtered films using standard photolithographic techniques, is an "H" or "dumbbell" shape with a narrow crossbar. With crossbars 0.1 mm wide, in excess of 1.5 mA of emission current is typically seen with a current of 15 mA through the sample and 300 V on a collector 2 cm from the sample. The emitters are physically rugged and are not damaged by operation in a vacuum as poor as 10 -5 Torr.
作者：
BECKER, LOUIS A.SIEGRIST, FRANKLIN I.Louis A. Becker was born in New Rochelle
N.Y. in 1930 receiving his earlier education in the New Rochelle Public Schools. He completed his undergraduate studies at Manhattan College in 1952 receiving his BCE degree during which time he was also engaged in land surveying. Following this he did postgraduate study at Virginia Polytechnic Institute obtaining his MS in 1954. He joined Naval Ship Research and Development Center in 1953 as a Junior Engineer and is currently the Head of the Engineering & Facilities Division Structures Department. His field of specialization is Structural Research and Development. Franklin I. Siegrist was born in Knoxville
Tenn. in 1937 receiving his earlier education in the Public Schools of Erie Pa. He attended Pennsylvania State University graduating in 1962 with a Bachelor of Science degree in Electrical Engineering having prior to that time served four years in the U. S. Navy. He was a Junior Engineer in the AC Spark Plug Division of General Motors from 1962 until 1964 at which time he came to the David Taylor Model Basin as an Electrical Engineer in the Industrial Department. He is currently Supervisory Engineer for Electrical and Electronics Engineering Structures Department Naval Ship Research and Development Center. His field of specialization is Electrical Engineering Control Systems Data Collection Systems Computer Applications to Structural Research and Hydraulic System Design. In the last of these he holds Patent Rights on a “Hydraulic Supercharge and Cooling Circuit” granted in 1970.
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