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The behavior of imperfect columns in conventional testing machine loading is investigated in the case when the buckling stress exceeds the elastic limit of the material. The behavior of the perfect column is then obtained through a limiting process in which the amplitude of the initial deviations from straightness is made to approach zero. It is found that a perfect column cannot bend at or above the tangent modulus load without stress reversal. The maximum load supported by the column is smaller than the reduced modulus load, and it can be smaller than, equal to, or greater than the tangent modulus load. (Author).

The eye globe was treated as a spherical shell (combined cornea and sclera) filled with (vitreous and aqueous) and surrounded by (tissue and fat) incompressible, inviscid, irrotationally flowing fluids. Its dynamic behavior was investigated by making use of the Flugge shell equations and the appropriate inertia terms. The axisymmetric case was solved in closed form, and the asymmetric case was solved numerically. Some qualitative results for physiologically meaningful parameter values are given. Static and dynamic experiments were performed on enucleated dog eyes. The static experiment measured the change in volume of the eyes as a function of time at various pressures. The results of this experiment indicated that the eyes were viscoelastic with an associated time constant of approximately 20 minutes. (Author).

This work is a theoretical study of the effect of ambient vibrational nonequilibrium(vibrational or radiative) on the propagation of acoustic and gravity waves in a gas. In the propagation of such waves, nonequilibrium phenomena can manifest themselves in two distinct ways. This follows from the fact that nonequilibrium can exist in either(or both) the ambient and perturbed states of the gas. It is well known that perturbation nonequilibrium always contribute to damping of the waves. The lesser known effects of ambient nonequilibrium are examined here from the point of view of macroscopic gas dynamics. The physical insight obtained in a one-dimensional analysis is applied to the study of the probable effect of vibrational nonequilibrium(ambient and perturbation) on the propagation of acoustic-gravity waves in Earth's upper atmosphere.

The basic problem dealt with in the paper is the identification of stochastic, discrete, multivariable linear systems from input-output data. The problem definition includes the possibility of both deterministic and stochastic inputs, although all the noise sources are restricted to be gaussian and white. Using an innovations formulation of the maximum likelihood criterion, the author is able to obtain probability one convergence of the impulse response matrices to their true values. From these matrices one develops a canonical form for multivariable linear systems which requires no structural information or other prior knowledge of the system (although the results are derived in such a way that such knowledge can certainly be used if it is available). This canonical form is also useful in the least squares identification of multivariable systems. One presents two very satisfactory methods of identifying the dimension of a system, one based on the whiteness of the resulting error process and the other based on the relative decrease of the cost function as input must satisfy to guarantee the probability one convergence of the impulse response matrices, and one points out easy methods of constructing input sequences which satisfy these conditions. Finally, one presents both a working program to perform the identification and suggestions, based on computational experience, for possible improvements. (Author).