Design of mold to yield elastomeric membrane whose shape and size, when inflated, is similar to the shape of the human heart

Nearly five million Americans are living with heart failure and 550,000 new cases are diagnosed each year in the US. Amongst the new approaches to develop a better solution for Congestive Heart Failure, Ventricular Recovery (VR) holds the most promise. A team, under the guidance of Dr. Criscione in the Cardiac Mechanics Lab at Texas A&M University, is currently developing an investigative device which aims to assist in VR by restoration of physiological strain patterns in the myocardial cells. The contribution of this thesis has been towards the development of a molding apparatus that yields a polymeric membrane whose shape, when inflated, is similar to the shape of the human heart. This membrane would surround the epicardial surface of the heart, when used for the device being discussed and in particular for the prototypes being developed. Contribution also includes a testing apparatus that measures the inflation of a membrane and simulation to predict the behavior of isotropic ellipsoids upon inflation. After unsuccessful implementations of two processing techniques, the successful design, fabrication implementation and attachment method meets the design criteria and is based on a thermoforming technique. Inflation profiles for membranes developed using this technique were studied at different pressures, with the axis length as variable. At 1kpa, which is the normal coronary arterial pressure, the membrane with an axis length of 140mm was found to show a shape which is similar to the shape of the human heart. In order to better understand and predict the shape an isotropic ellipsoidal membrane would take upon inflation without experimentation, simulations were carried out. Successful conversion of ellipsoidal geometry, with a few degrees of freedom as parameters, aided in simulation

iPhone in NASA Ground Operations

A comprehensive review of the literature and historical background of NASA established a need for an easy-to-implement technological improvement to displaying procedures which is cost effective and risk reducing. Previous unsuccessful attempts have led this team to explore the practicality of using a mobile handheld device. The major products, inputs, resources, constraints, planning and effort required for consideration of this type of solution were outlined. After analyzing the physical, environmental, life-cycle, functional, and socio-technical requirements, a Functional Analysis was performed to describe the top-level, second-level, and third-level functions of the system requirements. In addition, the risk/value proposition of conversion to a new technology was considered and gave a blueprint for transitioning along with the tasks necessary to implement the device into the Vehicle Assembly Building's (VAB) current infrastructure. A Work Breakdown Structure (WBS) described the elemental work items of the implementation. Once the viability of this system was confirmed, a device was selected through use of technical design comparison methods including the Pugh Matrix and House of Quality. Comparison and evaluation of the Apple iPhone, Motorola Q, Blackberry, PC Notebook, and PDA revealed that the iPhone is the most suitable device for this task. This paper outlines the device design/ architecture, as well as some of the required infrastructure

Adaptive function allocation for human-machine systems: A comparative study of triggers, strategies and stabilization

An adaptive allocation system is capable of dynamically reallocating functions between different agents. In adaptive allocation, the need for reallocation can be determined using different parameters (trigger mechanisms) such as fluctuation in workload or changes in physiology of the human agent. The adaptation strategy can determine the amount of reallocation and set the new level of the automated agent. The first experiment evaluated the effects of trigger type (performance or heart rate) and adaptation strategy (complete reallocation or partial transformation) on the number of errors made. The presence of adaptive allocation reduced the number of errors. The ANOVA results indicate interaction effect between the trigger type and adaptation strategy. Due to the presence of an interaction effect, interpretations of the main effects of trigger type or adaptation strategy type are difficult. The combination of a partial transformation strategy and heart rate trigger mechanism resulted in substantially more (nearly 114%) errors than other combinations. The errors made in the other combinations were not significantly different. The second experiment monitored the level of automation over time for presence of stabilization. There is no strong evidence to indicate that the time to stabilization is less than 30 minutes. As the time to stabilization is more than 30 minutes, inferences about main effect of trigger type or adaptation strategy could not be made. Based on the contingency table analyses, there appears to be an effect of adaptation strategy on the mean level of automation and the effect of trigger type on the time of onset of stabilization. Based on the post-hoc ANOVA analyses, there appears to be an interaction effect between the trigger types and adaptation strategy type on the number of reallocations and the probability of a change in level of automation being observed