Informe de Seminario para optar al grado de Licenciado en Historia / Seminario de grado : Procesos políticos de postmemorias autoritarias. Chile en la segunda mitad del siglo XX

The influence of modal interactions on the response of harmonically excited flexible L-shaped metallic and composite structures has been investigated analytically and experimentally. Each metallic structure possesses a two-to-one internal resonance, while each composite structure possesses a three-to-one internal resonance and either a two-to-one or a one-to-·one internal resonance. For the metallic structures, a weakly nonlinear analysis is used to derive the autonomous system of equations which describe the evolution of the amplitudes and phases of the internally resonant modes. These equations are obtained for primary- and secondary-resonant excitations. The excitation frequency or amplitude is used as a control parameter and the resulting bifurcations (saddle-node, pitchfork, and Hopf bifurcations) are studied. Theoretical analyses for internally resonant systems are used to predict and explain the responses of the composite structures. / Ph. D.

This work examines the structural role of the ammonoid shell in supporting hydrostatic load and the role of shell shape in facilitating swimming. The history of studies of the role of the shell in supporting hydrostatic load is discussed first, and is followed by an analysis of the function of the septal suture. The discussion of swimming consists of a critique of the previous work which emphasized the use of Nautilus as a modem analogue for swimming in ammonoids. This is followed by a discussion of flow tank studies that I conducted to examine the role of shell shape in drag production and power consumption of swimming in ammonoids. It had long been thought that the the shells of chambered cephalopods served as buoyancy compensation devices. However, it was not until the 1960's that the internal pressure of the shell was demonstrated to be less than one atmosphere, and that the shell structure supports hydrostatic load. It is remarkable that the internal pressure of cephalopod shells was not ascertained until the 1960s. As early as 1832 the great anatomist Richard Owen called for an empirical investigation of this subject. Functional and adaptive explanations were in vogue in Owen's time as a consequence of William Paley's argument from design. During the late 19th and early 20th century adaptation and functional explanations were no longer emphasized in the interpretation of morphology; non-adaptive evolutionary ideas in vogue in this time period stressed the role of development as a guiding force. It was not until the mid 20th century that there was renewed interest in cephalopod functional morphology and the role of the shell in resisting implosion was ascertained. / Ph. D.

Conceptual work on the study of crime argues the need for new approaches to understanding the incidence and etiology of that social phenomenon. The purpose of the present study was to investigate the explanatory power of the deprivation-compensation model of criminality. This new model of crime commission incorporates two social psycholoical constructs - relative deprivation and limited rationality - which partially mediate the relationship between structural and interpersonal deprivation and the type of crime committed. In this research, I focus exclusively on women offenders. A two-part questionnaire was administered to 112 women inmates at three state correctional facilities located in Illinois. A personal history inventory provided basic demographic and crime-related information. Part two was comprised of items tapping relative deprivation and limited rationality. The proposed model received only minimal support. A consistent finding was the weak influence that structural and interpersonal deprivation had on the type of crime committed by women offenders; however, the path coefficients for both of these constructs to relative deprivation were statistically significant. Relative deprivation and limited rationality shared a statistically significant relationship to the type of crime committed by women offenders. Several alternative explanations for the findings are offered. Finally, a number of suggestions for the conduct of future research using relative deprivation and limited rationality are outlined. / Ph. D.

Alvin Gouldner, in his 1970 work The Coming Crisis of Western Sociology, put forth the proposition that the discipline of sociology would soon witness the decline and eventual entropy of the then dominant functionalist theoretical perspective. This thesis is tested vis-a-vis the measurement of influence of the leading figures of four competing theory groups, namely Talcott Parsons (functionalism), George Homans (exchange theory), Erving Goffman (the dramaturgical wing of symbolic interactionism), and Harold Garfinkel (ethnomethodology). The findings provide illuminations of both the past and current state of sociological theory. / Master of Science

High-response pressure measurements of a high-speed, 10- stage, axial-flow compressor operating in rotating stall are analyzed. Procedures used to digitize analog voltages and calibrate pressure transducers are presented. From total and static pressures measured at the exit of the test compressor, stall cell Mach number distributions are calculated and used to study the effects of discharge throttle levels and variable vane changes on the 10th-stage rotating stall cells. Results indicate that significant transition zones exist between the reverse flow and peak Mach number of the stall cell cycle. Since the axial Mach numbers of the stall cell cycle are constantly changing, the amount of leading and trailing edge transition zones and fully unstalled flow zones are not easily defined. A method is devised to approximate the different flow zone ranges and correlate them to in-stall pressure characteristic behavior of the 10th stage of the test compressor. Changes in the time-averaged pressure characteristics are found to correlate with changes in the rotating stall flow zones. A lower pressure coefficient appears to correspond to an increase in the ratio of trailing to leading edge transition zone size and the average transition zone size. Results also suggest that recovery hysteresis in the test compressor is characterized by reverse flow in the rotating stall cell. / Master of Science

The use of a modal domain fiber optic sensor for vibration control of a flexible cantilevered beam is experimentally demonstrated. The sensor utilizes mode-mode interference in a two mode elliptical core fiber. The sensor covers a major portion of the beam, and produces a measurement based on the strain distribution in the beam. A distributed-effect model is developed for the fiber optic sensor, and verified through both static and dynamic tests. This model is incorporated into a active control system employing dynamic output feedback. The control system is shown to add damping to the low order modes of the beam. Numerical simulations are presented which concur with the experimental responses, in both open and closed loop tests. / Master of Science

No description available.

A combination of Newton's second law, a transformation using three consecutive Euler angles, and Taylor expansions is used to develop three nonlinear integro-differential equations describing the flexural-flexural-torsional vibration of metallic and composite beams. The twisting curvature is used to define a physical twisting variable which makes the equations of motion unique and independent of the rotation sequence of the Euler angles. A numerical-perturbation approach is used to analyze the response of metallic and composite beams to parametric and external excitations. First, the linear eigenfunctions and natural frequencies are calculated using a combination of the state-space concept and the fundamental-matrix method. Then, the method of multiple scales is used to construct a set of nonlinear autonomous first-order ordinary-differential equations describing the slow-time modulation of the amplitudes and phases of the interacting modes in the presence of one-to-one and/or two-to-one internal resonances. The inversion symmetry, D, symmetry, and 0(2) symmetry of the system are studied using the modulation equations. The solutions of the modulation equations may be fixed points, limit cycles, or chaotic solutions. / Ph. D.

Several aspects of the subharmonic instability of boundary layers are studied. First, the subharmonic instability of incompressible flows over a flat plate is investigated using the resonant triad model and the Floquet model. The primary wave is taken in the form of a two-dimensional (2-0) Tollmien-Schlichting (T-S) wave. The subharmonic wave is taken in the form of a three-dimensional (3-D) wave. Results from both models are presented and compared with the experimental data and numerical simulation. It is found that the results of the Floquet model are in good agreement with the experimental data and numerical simulation, whereas the results of the resonant triad model agree only qualitatively with the experimental data. Second, the subharmonic instability of incompressible flows over a 2-0 hump is studied using the Floquet model. The mean flow over the hump is calculated by using interacting boundary layers, thereby accounting for viscid/inviscid interactions. The results show that increasing the hump height results in an increase in the amplification factors of the primary and subharmonic waves. When the hump causes separation, the growth rates of both the primary and subharmonic waves are considerably larger than those obtained in the case of no separation. Third, the subharmonic instability of compressible boundary layers over a flat plate is studied using the Floquet model. Results are presented for adiabatic wall boundary conditions and subsonic, transonic, and supersonic flows. For supersonic flows results are presented for first- and second-mode primary waves. The effect of Mach number, spanwise wavenumber, primary-wave amplitude, Reynolds number, and frequency are studied. Fourth, results for the effect of heat transfer on the subharmonic instability of a two-dimensional compressible boundary layer over a flat plate are presented for different Mach numbers. For supersonic flows results are presented for first- and second-mode waves. The effect of different levels of heat transfer on changing the features of the subharmonic compressible instability is evaluated. Fifth, results for the effect of suction on the subharmonic instability of a two-dimensional compressible boundary layer over a flat plate are presented. It is found that when the primary wave is a first-mode merging with a second-mode, the subharmonic wave is strongly destabilized by suction. Sixth, the effect of a bulge on the subharmonic instability of compressible boundary layers is studied. It is found that the effect of compressibility on reducing the growth rate of the disturbances weakens as the hump height increases. / Ph. D.