Showing papers by "Georgia Institute of Technology published in 1970"

Intermodal Equivalence of Stimuli in Apes

Abstract: Orang-utans and chimpanzees can discriminate between two objects on the basis of tactile cues and select the one that matches a visually presented sample.

Computer-aided radome analysis

Abstract: A procedure is presented for predicting by computer the radiation pattern of an antenna in the presence of a radome. The case of a horn antenna radiating through an actual aircraft radome is treated in detail, and a comparison is made between computed and measured antenna patterns. Good agreement between theory and experiment is noted.

Stochastic Behavior of Resonant Nearly Linear Oscillator Systems in the Limit of Zero Nonlinear Coupling

Abstract: This paper investigates the classical motion of oscillator systems governed by Hamiltonians having the nearly linear form $H=\ensuremath{\Sigma}\stackrel{N}{k=1}\frac{{\ensuremath{\omega}}_{k}}{2}({{P}_{k}}^{2}+{{Q}_{k}}^{2})+\ensuremath{\gamma}({V}_{3}+{V}_{4}+\ensuremath{\cdots}),$ where $N$ is the number of oscillators, ${\ensuremath{\omega}}_{k}$ are the positive frequencies of the harmonic approximation, $\ensuremath{\gamma}$ is the nonlinear coupling parameter, and ${V}_{3}$, ${V}_{4}$, etc., are cubic, quartic, etc., polynomials in ${Q}_{k}$ and ${P}_{k}$. The purpose of this investigation is to demonstrate that macroscopic irreversibility is an inherent property of physical, nearly linear oscillator systems even in the limit as $\ensuremath{\gamma}$ tends to zero. Irreversibility occurs for these systems because of the appearance of resonance overlap, which causes the system trajectories to wander more or less randomly over part or most of the energy surface. Resonance overlap can occur for arbitrarily small but nonzero $\ensuremath{\gamma}$ provided that $N\ensuremath{\ge}3$ and that the ${\ensuremath{\omega}}_{k}$ satisfy commensurability conditions which allow the ${V}_{3}$ and/or ${V}_{4}$ interaction terms to resonantly couple all internal degrees of freedom. These results are demonstrated through an extensive computer study of the case $N=3$. This case is especially suitable for study since it possesses much of the complexity of the full many-body problem and yet is sufficiently simple to yield to level-curve analysis which provides an especially lucid pictorial display of the random motion of individual trajectories. In addition, the computer study shows that one consequence of resonance overlap is that system trajectories originally close to each other in phase space can move apart more or less exponentially with time. This exponential stirring of phase space is of the type which Gibbs envisioned as leading to irreversible behavior. In particular, the slightest uncertainty of the initial state leads very quickly to complete uncertainty of the final state. Moreover, resonant oscillator systems share ownership of exponentially divergent trajectories with gaseous systems. Indeed, this property, which is a direct consequence of the equations of motion, is perhaps the ultimate source of irreversibility.

A theory of laminated cylindrical shells consisting of layers of orthotropic laminae

Abstract: The development of a general linear theory and the derivation of equations of motion for the analysis of laminated cylindrical shells consisting of layers of orthotropic laminae is presented The classical Kirchhoff hypothesis of nondeformable normals commonly used for isotropic shells is abandoned so that compatible shear stresses and deformation between layers can be maintained Transverse inextensibility of each layer is assumed; however, the normal stresses in the transverse direction are accounted for so that the peeling stresses between layers may be determined The transverse coordinate a, when compared to the radius of the midsurface of each layered cylinder, is generally small; however, it is not neglected in the general derivation The general procedure in the derivation is similar to that presented by Ambartsumian for orthotropic plates However, the resulting governing differential equations are substantially more complicated than those for orthotropic plates

Linear-Momentum Flux to Overbank Sections

Abstract: On the basis of experiments in two joined rectangular channels, transfer of linear momentum from the major (less restricted) channel to the minor (more restricted) channel has been demonstrated. The apparent-shear stress on the junction surface was found to be of the same order of magnitude as the boundary-shear stress in the major channel. Based upon this observation, a method for engineering calculations for mean-flow characteristics in joined channels such as a river at flood stage is proposed. The steps in the proposed separate-channel method of analysis are: (1) considering the major-channel boundary including the junction plane as a solid boundary, compute the mean boundary-shear stress on the major-channel boundary; (2) compute the apparent-shear force on the junction surface using the mean boundary-shear stress of the major channel; and (3) incorporate the apparent-shear force on the junction surface as a propulsive force on the minor-channel flow.

Order-induced strengthening in Ni4Mo

Abstract: Polycrystalline samples of Ni4Mo have been examined at various stages of isothermal ageing at 700° C. The mechanical properties were measured on initially disordered samples at various stages of the ordering process. These properties were correlated with microstructural observations such as domain size, degree of order and fracture characteristics. The correlations are rationalised in terms of a model for the ordering process and its effect on dislocation motion.

Activation Cross Sections for ( n , 2 n ) Reactions at 14.4 MeV in the Region Z = 40 − 60 : Precision Measurements and Systematics

Abstract: Activation cross sections for the ($n, 2n$) reaction in the region of $Z=40\ensuremath{-}60$ at 14.4\ifmmode\pm\else\textpm\fi{}0.3 MeV have been measured by using the mixed-powder method and Ge(Li) $\ensuremath{\gamma}$-ray detection. The total cross sections ($m+g$) measured are (in mb) ${\mathrm{Zr}}^{90}$, 652\ifmmode\pm\else\textpm\fi{}31; ${\mathrm{Zr}}^{96}$, 1456\ifmmode\pm\else\textpm\fi{}80; ${\mathrm{Mo}}^{92}$, 217\ifmmode\pm\else\textpm\fi{}18; ${\mathrm{Mo}}^{100}$, 1389\ifmmode\pm\else\textpm\fi{}84; ${\mathrm{Ru}}^{96}$, 569\ifmmode\pm\else\textpm\fi{}30; ${\mathrm{Ru}}^{98}$, 1168\ifmmode\pm\else\textpm\fi{}96; ${\mathrm{Ru}}^{104}$, 1440\ifmmode\pm\else\textpm\fi{}80; ${\mathrm{Rh}}^{103}$, 957\ifmmode\pm\else\textpm\fi{}57; ${\mathrm{Pd}}^{102}$, 637\ifmmode\pm\else\textpm\fi{}45; ${\mathrm{Pd}}^{110}$, 1416\ifmmode\pm\else\textpm\fi{}150; ${\mathrm{Cd}}^{108}$, 865\ifmmode\pm\else\textpm\fi{}100; ${\mathrm{Cd}}^{110}$, 1221\ifmmode\pm\else\textpm\fi{}150; ${\mathrm{Cd}}^{116}$, 1389\ifmmode\pm\else\textpm\fi{}71; ${\mathrm{Sn}}^{114}$, 1239\ifmmode\pm\else\textpm\fi{}130; ${\mathrm{Sb}}^{121}$, 1615\ifmmode\pm\else\textpm\fi{}63; ${\mathrm{Sb}}^{123}$, 1542\ifmmode\pm\else\textpm\fi{}80; ${\mathrm{Te}}^{122}$, 1615\ifmmode\pm\else\textpm\fi{}110; ${\mathrm{Te}}^{128}$, 1661\ifmmode\pm\else\textpm\fi{}161; ${\mathrm{Te}}^{130}$, 1455\ifmmode\pm\else\textpm\fi{}55; ${\mathrm{I}}^{127}$, 1649\ifmmode\pm\else\textpm\fi{}80; ${\mathrm{Cs}}^{133}$, 1542\ifmmode\pm\else\textpm\fi{}75; ${\mathrm{Ba}}^{132}$, 1574\ifmmode\pm\else\textpm\fi{}100; ${\mathrm{Ce}}^{136}$, 1318\ifmmode\pm\else\textpm\fi{}90; ${\mathrm{Ce}}^{140}$, 1593\ifmmode\pm\else\textpm\fi{}130; and ${\mathrm{Ce}}^{141}$, 1730\ifmmode\pm\else\textpm\fi{}170. Some partial ($n, 2n$) cross sections also are reported. The measured values are compared with the semiempirical predictions of Pearlstein and of Gardner. No significant shell effects are seen, and the data suggest that 14-MeV ($n, 2n$) reactions are governed predominantly by the statistical model of the compound nucleus. An empirical fit for the ratio of neutron emission to all modes of compound-nucleus decay, $\frac{{\ensuremath{\sigma}}_{n,M}}{{\ensuremath{\sigma}}_{\mathrm{ne}}}$, is deduced from the present results.

Jet Pump Cavitation

Abstract: Mixing-throat cavitation in a liquid jet pump results from high jet velocities, low suction (NPSH) pressure, or low discharge pressure. Incipient cavitation at the jet boundary has no effect on jet pump efficiency, but under severe conditions it spreads to the walls. A limiting flow condition results which is independent of discharge pressure. Efficiency deteriorates rapidly and the pump head-flow characteristics can no longer be predicted by conventional theory. Eight correlation parameters (1937–1968) and their interrelations are examined. A Cavitation Index σL is recommended for correlation of cavitation-limited flow results. Limiting flow data from 14 references on water, oils, and mercury, plus additional data on three water jet pumps are compared, showing that 11 sets of data on water, oils, and mercury can be represented by the single-number index σL , with a range of 0.8 to 1.67. Conventional jet pumps are described by σL = 1.0 to 1.4 and σL = 1.35 is recommended for conservative use. The limiting flow function Y (NPSH) is shown to be a useful tool in comparing cavitation response to design changes. System design to avoid cavitation is facilitated by a simple limiting flow equation, ML (R, σL , NPSH, Vn ), and the equation is compared with recently published data. Cavitation can be avoided by reducing Vn , and R, or by raising suction port pressure. Flow passage contours, including nozzle-to-throat spacing, influence σL and the limiting flow ratio can also be improved by reducing σL (0.9 or less) through careful design. Systems handling high gas-solubility liquids can be improved by reducing gas content; fluid properties otherwise have little effect on this jet pump phenomenon.

Application of the Galerkin method in the solution of combustion-instability problems.

Abstract: A new approach for the solution of combustion instability problems is presented. In this study the Galerkin method is used to analyze the behavior of the flow field in a rocket combustor with mass, momentum and energy sources present on its boundaries and in the flow field. The presence of sources on the boundaries results in mathematically complicated boundary conditions that must be satisfied by the solutions. The “classical” Galerkin method, which was previously used in cases where the solution of the problem had to satisfy relatively simple boundary conditions, is modified in order to satisfy the more complicated boundary conditions which are encountered in combustion instability problems. The applicability of the modified Galerkin method is demonstrated when it is used to solve a specific problem whose solution is available. It is shown that the results produced by the Galerkin method are in complete agreement with the available solution.

New variational principle in electromagnetics

Abstract: A new variational principle that applies to a wide class of electromagnetic problems is presented. This principle has the distinctive characteristic of always producing linear algebraic equations when the Rayleigh-Ritz procedure is applied using a trial field composed of a linear combination of variational parameters. The new technique is applied to a general class of antenna problems, and is specialized to the case of a dielectrically coated slot antenna. Experimentally observed admittance values at X band are presented and compared with theoretical predictions.

K, Ar, Illite Burial

Abstract: K, Ar, and mineral analyses of montmorillonitic mud samples 4233 ft to 16,450 ft deep from a well in the Mississippi Delta area show that, with depth, the apparent K-Ar ages of the bulk samples decrease 100 m.y.; the >2 μ fraction is relatively constant in apparent age at approximately 400 m.y.; and the apparent age of the μ fraction decreases 40 m.y. with depth. With increasing depth and temperature, K (0.8 percent) appears to be released from the course K-feldspar and mica and to become fixed between the montmorillonite layers. Due to the formation of chloritic layers, fewer illitic layers are formed than is commonly supposed. K-Ar data may be useful in reconstructing the thermal and burial history of shales.

Generalized Penalty-Function Concepts in Mathematical Optimization

Abstract: Given a mathematical program, this paper constructs an alternate problem with its feasibility region a superset of the original mathematical program. The objective function of this new problem is constructed so that a penalty is imposed for solutions outside the original feasibility region. One attempts to choose an objective function that makes the optimal solutions to the new problem the same as the optimal solutions to the original mathematical program.

Activation Cross Sections for ( n , p ), [ ( n , n p ) + ( n , p n ) + ( n , d ) ], and ( n , α ) Reactions in the Region of Z = 40 to 58 at 14.4 MeV

Abstract: The following activation cross sections (in mb) for the ($n, p$), [$(n, np)+(n, pn)+(n, d)$] and ($n, \ensuremath{\alpha}$) reactions in the region of $Z=40\ensuremath{-}58$ have been determined at 14.4\ifmmode\pm\else\textpm\fi{}0.3 MeV by using the mixed powder method with Ge(Li) $\ensuremath{\gamma}$-ray detection: ${\mathrm{Zr}}^{90}(n, p){\mathrm{Y}}^{90m}$ (3.1 h), 12.9\ifmmode\pm\else\textpm\fi{}1.0; ${\mathrm{Zr}}^{91}(n, p){\mathrm{Y}}^{91m}$ (50.3 min), 18.6\ifmmode\pm\else\textpm\fi{}1.9; ${\mathrm{Zr}}^{92}(n, p){\mathrm{Y}}^{92}$ (3.53 h), 18.5\ifmmode\pm\else\textpm\fi{}2.7; ${\mathrm{Mo}}^{92}(n, p){\mathrm{Mb}}^{92m}$ (10.1 day), 62.5\ifmmode\pm\else\textpm\fi{}4.0; ${\mathrm{Mo}}^{96}(n, p){\mathrm{Nb}}^{96}$ (23.35 h), 21.3\ifmmode\pm\else\textpm\fi{}1.5; ${\mathrm{Mo}}^{97}(n, p){\mathrm{Nb}}^{97m}$ (1 min), 7.4\ifmmode\pm\else\textpm\fi{}0.8; ${\mathrm{Mo}}^{97}(n, p){\mathrm{Nb}}^{97g}$ (72 min), 8.5\ifmmode\pm\else\textpm\fi{}1.0; ${\mathrm{Mo}}^{98}(n, p){\mathrm{Nb}}^{98g}$ (51 min), 4.1\ifmmode\pm\else\textpm\fi{}0.5; ${\mathrm{Ru}}^{96}(n, p){\mathrm{Tc}}^{96}$ (4.35 day), 146\ifmmode\pm\else\textpm\fi{}7; ${\mathrm{Rh}}^{103}(n, p){\mathrm{Ru}}^{103}$ (39.5 day), 16.9\ifmmode\pm\else\textpm\fi{}1.5; ${\mathrm{Pd}}^{105}(n, p){\mathrm{Rh}}^{105}$ (35.9 h), 37.6\ifmmode\pm\else\textpm\fi{}2.0; ${\mathrm{Pd}}^{106}(n, p){\mathrm{Rh}}^{106m}$ (130 min), 6.0\ifmmode\pm\else\textpm\fi{}0.4; ${\mathrm{Pd}}^{106}(n, p){\mathrm{Ru}}^{106g}$ (30 sec), 18\ifmmode\pm\else\textpm\fi{}4; ${\mathrm{Pd}}^{108}(n, p){\mathrm{Rh}}^{108}$ (16.8 sec), 8.3\ifmmode\pm\else\textpm\fi{}1.5; ${\mathrm{Cd}}^{112}(n, p){\mathrm{Ag}}^{112}$ (3.14 h), 15.0\ifmmode\pm\else\textpm\fi{}1.3; ${\mathrm{Sn}}^{116}(n, p){\mathrm{In}}^{116m}$ (54 min), 7.9\ifmmode\pm\else\textpm\fi{}0.8; ${\mathrm{Sn}}^{117}(n, p){\mathrm{In}}^{117m}$ (1.93h), 5.7\ifmmode\pm\else\textpm\fi{}1.5; ${\mathrm{Sn}}^{117}(n, p){\mathrm{In}}^{117g}$ (45 min), 9.8\ifmmode\pm\else\textpm\fi{}1.6; ${\mathrm{Ba}}^{138}(n, p){\mathrm{Cs}}^{138}$ (32.2 min), 3.8\ifmmode\pm\else\textpm\fi{}0.6; ${\mathrm{Ce}}^{140}(n, p){\mathrm{La}}^{140}$ (40.22 h), 6.3\ifmmode\pm\else\textpm\fi{}0.5; ${\mathrm{Zr}}^{94}(n, \ensuremath{\alpha}){\mathrm{Sr}}^{91}$ (9.67 h), 5.0\ifmmode\pm\else\textpm\fi{}1.0; ${\mathrm{Nb}}^{93}(n, \ensuremath{\alpha}){\mathrm{Y}}^{90m}$ (3.1 h), 5.3\ifmmode\pm\else\textpm\fi{}0.5; ${\mathrm{Mo}}^{92}(n, \ensuremath{\alpha}){\mathrm{Zr}}^{89m}$ (4.18 min), 9.4\ifmmode\pm\else\textpm\fi{}0.9; ${\mathrm{Mo}}^{92}(n, \ensuremath{\alpha}){\mathrm{Zr}}^{89g}$ (78.4 h), 18.7\ifmmode\pm\else\textpm\fi{}1.5; ${\mathrm{Mo}}^{98}(n, \ensuremath{\alpha}){\mathrm{Zr}}^{95}$ (65.5 day), 8.1\ifmmode\pm\else\textpm\fi{}1.0; ${\mathrm{Pd}}^{106}(n, \ensuremath{\alpha}){\mathrm{Ru}}^{103}$ (39.5 day), 5.6\ifmmode\pm\else\textpm\fi{}0.7; ${\mathrm{Pd}}^{108}(n, \ensuremath{\alpha}){\mathrm{Ru}}^{105}$ (4.44 h), 2.7\ifmmode\pm\else\textpm\fi{}0.3; ${\mathrm{Cs}}^{133}(n, \ensuremath{\alpha}){\mathrm{I}}^{130}$ (12.3 h), 1.96\ifmmode\pm\else\textpm\fi{}0.15; ${\mathrm{Ba}}^{138}(n, \ensuremath{\alpha}){\mathrm{Xe}}^{135m}$ (15.6 min), 0.55\ifmmode\pm\else\textpm\fi{}0.05; ${\mathrm{Ba}}^{138}(n, \ensuremath{\alpha}){\mathrm{Xe}}^{135g}$ (9.14 h), 2.0\ifmmode\pm\else\textpm\fi{}0.2; ${\mathrm{Ce}}^{142}(n, \ensuremath{\alpha}){\mathrm{Ba}}^{139}$ (82.9 min), 6.0\ifmmode\pm\else\textpm\fi{}1.0; ${\mathrm{Ru}}^{96}[(n, np)+(n, pn)+(n,d)]{\mathrm{Tc}}^{95m}$ (61.0 day), 52\ifmmode\pm\else\textpm\fi{}10; and ${\mathrm{Ru}}^{96}[(n, np)+(n, pn)+(n, d)]{\mathrm{Tc}}^{95g}$ (20 h), 483\ifmmode\pm\else\textpm\fi{}50. The total ($n, p$) cross sections are compared with Levkovskii's predictions and show good agreement. The relative ($n, p$) cross sections of Mo and Pd also are compared with Gardner's predictions.