A digital simulation of the cardiovascular and pulmonary systems of a newborn infant was developed and tested. More specifically, the model was designed to emulate the blood gas chemistry of the neonate and it's effect on respiratory stimulus, cardiac output and Ductus Arteriosus shunting. Pulmonary and cardiac system dynamics were not considered in the simulation. The model underwent a series of tests in which controlled mockups of actual physiological conditions were simulated. The effect of metabolic rate changes, Ductus Arteriosus shunting, and alveolar membrane disease on the pulmonary and cardiovascular systems was studied in steady state conditions. The dynamic alterations in the neonatal system due to respirator therapy and carbon dioxide inhalation was investigated. Finally, a simulation of an actual clinical case was undertaken. While the model worked well in the controlled environment tests, it showed some deficiencies in the clinical case study. Additional clinical data is needed to improve the respiratory and cardiac control mechanisms in the simulation. Further, a more complete blood buffer system needs to be incorporated into the model. / M.S.

No description available.

No description available.

No description available.

No description available.

No description available.

A systematic study of the core structures of (100), (110), and (111) dislocations in B2 NiAI has been conducted using atomistic simulations with an embedded atom method (EAM) potential. New flexible boundary conditions and a new method of graphic representation of dislocation core structure have been employed. The main findings are the following: Core structures: There are no planar core structures of the dislocations found in B2 NiAl. The core spreading of (100) dislocations in NiAl can occur along a variety of planes depending on dislocation slip plane and line orientation. Discrete lattice effects reduced the high strain levels from anisotropic elasticity solution at the dislocation core considerably and resulted in asymmetrical core structures. The core structure of the (110) dislocations is mutilayered with spreading on the {110} plane. The extent of the same strain level comparing with (100) and (111) dislocations is much larger. The complete (111) dislocations in NiAl are also highly non-planar and are stable with respect to splitting into exact 1/2(111) partials as well as to alternative splittings that correspond to the stable fault in the vicinity of the antiphase boundary (APB), in both {110} and {112} planes. Peierls stresses: Peierls stresses of the dislocations have been calculated and have been compared for their relative ease of motion. Local disordering effects: The local disordering effects on the core structure are found to be significant only in the immediate vicinity of the point defect. Compositional deviation from stoichiometry: The simulation results of (100), (110), and (111)dislocations in off stoichiometric NiAl show that the core structures became more extended than the ones in the stoichiometric NiAl. The core structures are not only dependent on the overall composition but also on their local atomic arrangement near the core region. When compositional deviation from stoichiometry is introduced, the response to the applied stress is different for the various slip systems. The Peierls stresses for the usually easiest moving (100){110} dislocations increased and for the (100){100} dislocations decreased, and the latter are expected to be more active in the deformation processes. The practical implications of these results are that it seems very difficult to modify the alloy behaviors through local changes in stoichiometry and ordering state. The best way to improve the ductility of B2 NiAl is to stabilize (111) slip through the addition of alloying elements that can lower the APB energy. / Ph. D.

Public policy and program implementation has come to be regarded as a significant problem area in the governance process. Research has provided insights but falls short of totally satisfactory prescriptions for operational success. The literature on policy and program implementation reflects a dichotomy of means between centralized control and delegation of substantial discretionary authority. The resulting theory leaves a gap with practice. Scenario writing is one of the techniques available to practitioners that might be employed to assist in the execution of their responsibilities. Scenarios can be useful tools, but their preparation is costly and time consuming. It was hypothesized that computer modeling techniques and artificial intelligence could be applied to scenario generation to create an effective, practical instrument to permit wider and more effective use of scenarios for planning and management. A computer supported procedure is presented for generating scenarios which describe alternative sequences of future events for a given situation and proposed policy. The generator design reflects a three-way compromise between processing flexibility, data-base structure, and user workload requirements. This prototype generator was subjected to exploratory trials. The lessons learned highlight some potentially valuable program improvements, the importance of focusing the scenario at a level useful to the reader, and the need for a common set of definitions. / Ph. D.

A generalized solution technique has been designed and developed for the static and dynamic analysis of induced strain actuated beam structures. A PC-based, user-friendly, menu-driven software program DAISA (Dynamic Analysis of Induced Strain Actuated Beams) has been developed for the analysis of structural response due to induced strain actuation, with a highly user-friendly interface. Transfer matrices have been used to generalize the beam problem to accommodate different boundary conditions, loading conditions due to an arbitrary number of symmetric actuator patches on the beam structure, structural damping effects, and the effects of stiffening and mass loading due to the presence of the actuators. DAISA has been designed to perform static-response, free-vibration, steady-state harmonic-response, and frequency-response analyses describing the structural response to induced strain actuation. Various modeling techniques, including the Static, equivalent thermal expansion, and impedance approaches have been incorporated. DAISA has also been equipped to perform an electro-mechanical analysis of the beam-actuator system thereby providing adequate information about power consumption and system power requirements. The algorithm and software presented in this thesis will serve to achieve better design considerations for actuators employed in structural and vibration control. / Master of Science

This study investigated the influence of the attainable region technique to ball milling as applied in reactor technology. Flow rate, ball filling, mill speed, ball size and mill density were varied. When each was varied, the rest of the parameters were kept constant in-order to determine the influence of each parameter on the process of milling. Selection function and breakage function parameters were selected for the mill model. These were kept constant for all four circuit configurations: open milling circuit, normal closed circuit, reverse closed circuit, and combined closed circuit. Flow rate was varied from 10 tph to 150 tph. It was observed that in all circuit configurations the optimum results were obtained from 90 tph upwards. When ball filling was varied, the optimum results were obtained between 30 % and 40 % of ball filling. At this range the mill is neither experiencing under-filling nor over-filling. When the mill speed was varied, at 60 – 80 % of critical speed the product specification was achieved and for grinding balls, sizes of between 60 mm and 90 mm yielded the optimum results. Varying the mill density resulted in insignificant changes. From the results, the combined closed circuit produced more of the product specification. / School of Engineering / M. Tech. (Engineering: Chemical)