The development of computational techniques for the identification of linear and nonlinear mechanical systems subject to random excitation, part 2 Final report

Computational techniques for identifying linear and nonlinear mechanical systems subject to random excitatio

The uncanny body: from medical to aesthetic abnormality

In this essay I explore a possibility of experiential synthesis of the medicalized abnormal body with its aesthetic images. A personal narrative about meeting extreme abnormality serves as an introduction into theorizing aesthetic abnormality. The essay builds its argument on the phenomenological grounds; I therefore approach corporeality with Edmund Husserl and Maurice Merleau-Ponty. In turn, Max Ernst introduces an aesthetic frame for the subsequent examination of uncanny surreality. Two exemplars of the surreal body, Joel Witkin’s “Satiro” and Don DeLillo’s “Body Artist,” intend to substantiate the preceding theoretic. The study shows how the encounter with the abnormal embodiment may suspend normalized modes of constitution to provoke uncanny experience

Identification of linear systems. Simulation studies Final report, Feb. 1967 - Apr. 1968

Analytical development and computerized simulation of parameter estimation technique for identifying linear and nonlinear system

On the arithmetic of one del Pezzo surface over the field with three elements

We discuss the problem of existence of rational curves on a certain del Pezzo surface from a computational point of view and suggest a computer algorithm implementing search. In particular, our computations reveal that the surface contains 920 rational curves with parametrizations of degree 8 and does not contain rational curves for a smaller degree

Review of probabilistic analysis of dynamic response of systems with random parameters

The various methods that have been studied in the past to allow probabilistic analysis of dynamic response for systems with random parameters are reviewed. Dynamic response may have been obtained deterministically if the variations about the nominal values were small; however, for space structures which require precise pointing, the variations about the nominal values of the structural details and of the environmental conditions are too large to be considered as negligible. These uncertainties are accounted for in terms of probability distributions about their nominal values. The quantities of concern for describing the response of the structure includes displacements, velocities, and the distributions of natural frequencies. The exact statistical characterization of the response would yield joint probability distributions for the response variables. Since the random quantities will appear as coefficients, determining the exact distributions will be difficult at best. Thus, certain approximations will have to be made. A number of techniques that are available are discussed, even in the nonlinear case. The methods that are described were: (1) Liouville's equation; (2) perturbation methods; (3) mean square approximate systems; and (4) nonlinear systems with approximation by linear systems

Bifurcation in Rotational Spectra of Nonlinear AB2_2 Molecules

A classical microscopic theory of rovibrational motion at high angular momenta in symmetrical non-linear molecules AB$_2$ is derived within the framework of small oscillations near the stationary states of a rotating molecule. The full-dimensional analysis including stretching vibrations has confirmed the existence of the bifurcation predicted previously by means of the rigid-bender model. The formation of fourfold energy clusters has already been experimentally verified for H$_2$Se and it has been demonstrated in fully-dimensional quantum mechanical calculations using the MORBID computer program. We show in the present work that apart from the level clustering, the bifurcation produces physically important effects including molecular symmetry-breaking and a transition from the normal mode to the local mode limit for the stretching vibrations due to rovibrational interaction. The application of the present theory with realistic molecular potentials to the H$_2$Te, H$_2$Se and H$_2$S hydrides results in predictions of the bifurcation points very close to those calculated previously. However for the lighter H$_2$O molecule we find that the bifurcation occurs at higher values of the total angular momentum than obtained in previous estimations. The present work shows it to be very unlikely that the bifurcation in H$_2$O will lead to clustering of energy levels. This result is in agreement with recent variational calculations.Comment: latex, 19 pages including 2 figures provided as *.uu fil