There are a number of applications, from hearing aids to microfluidic pumps, which utilize micro-scale actuating diaphragms. These MEMS (micro-electromechanical system) devices can be actuated by electrostatic forces, which utilize an induced electric field to pull two charged plates towards one another. Such devices were fabricated and electrostatic actuation of the diaphragms was performed to analyze its viability as a micro-speaker. The long-term performance of such products requires adequate diaphragm deflection to create audible pressure waves with relatively low maximum stresses to ensure a high cycle fatigue life. With these requirements, initial calculations and FEA (finite element analysis) were performed to establish the optimal square diaphragm side length combined with an attainable gap between electrodes to achieve an audible response. Optical and acoustic testing was then performed on 4, 5, and 7 mm side length square diaphragms with 10 μm thickness and a 70 μm electrode gap. For the 5 mm device and a 300 V applied potential, deflection was calculated to be 4.12 μm theoretically and 3.82 μm using FEA, although deflections based on optical test data averaged 30.53μm under DC conditions. The DAQ used for optical testing was extremely limiting due to its fastest sampling interval of 89 milliseconds, so this testing was performed at 2 and 5 Hz. Although the 7 mm device generated audible noise at 300 V and 2 kHz when the observer was within approximately 6 inches of the device, acoustic testing with a microphone placed 1 inch from the device did not yield any definitive results.

Cochlear implants are devices, which are implanted into the cochlea to aid hearing via stimulation of the cochlear nerve. For this study, we were interested in understanding the age-related changes in the impedances of the electrodes implanted with a cochlear implant system. The impedances of the electrodes reflect the integrity of the implanted system in the inner ear, and the efficiency of transmission of information from the externally worn device to the implanted system. Thus, monitoring cochlear impedances is important for the patient's rehabilitation. Our hypothesis was that cochlear implant impedances would decrease as an effect of age. Current systems record the impedances via a telemetry system when the patient’s cochlear implant is connected to the programming software. This data is saved within the system and can be retrieved and de-identified within the software. In our investigation, we collected the de-identified impedance data from this system to understand the effects of age. This data was collected from the ETSU Audiology Clinic at the Nave Center. The de-identified data was reviewed and sorted between 3 different age brackets. Data was averaged and compared between age brackets and electrodes. Overall, we found in this study that there are no significant differences between age brackets when comparing cochlear implant impedances across the different electrodes. The slight differences between impedances across electrodes and age brackets could be due to many contributing factors, however, the differences were not considered statistically significant. This study could indicate future directions for further research including, comparing impedance differences between male and female subjects, longitudinal case studies, and comparing across implant manufacturers and device type.

Background: 33.6% of all deaths in America are caused by cardiovascular disease. An estimated 82.6 million adults (>1 in 3) in America have some form of cardiovascular disease. There were over 400,000 bypass surgeries requiring open-heart surgery. Sternal dehiscence is associated with a morbidity rate of over 47% if mediastinitis supervenes. A rigid closure is required to avoid healing complications, and wire, plates, and bands are all used in an attempt to make a better closure. The purpose of this study it to compare multiple closures and validate a new testing method. Methods: Polyurethane foam blocks will be used, as an alternative to cadavers, to provide homogeneous samples to test and compare multiple closure techniques. Each closure was performed by an engineer after instruction from a cardiothoracic surgeon and the SternaLock plate manufacturers. Seven different closure techniques (single suture, double suture, figure-eight suture, Robicsek weave, Sternalock Silver, Sternalock Blu, and Sternalock Wide Ladder) were compared in both lateral distraction and longitudinal shear. Statistical analysis was used to show the differences in stiffness, yield force, failure force, and yield displacement of each closure method. Results: Under lateral distraction, double wire closure showed the greatest stiffness followed by the Sternalock plates. The Sternalock plates had the greatest failure and yield forces, whereas the double wire performed significantly poorer. The longitudinal testing revealed that the wires provide no resistance to the shearing forces on the sternum, but the screws for plates can allow for multidirectional loading. Conclusions: Overall Sternalock plates are less likely to fail in all directions compared to wired closures. Even though double wire closures displayed a higher average lateral stiffness, the high stress concentrations created by wires allowed for easy foam cutting and much lower yield force and failure force. Testing using foam blocks as sternal analogues produces highly reproducible results, with less variance than cadaveric tests.

Fluoroscopy is considered the gold standard for locating catheters during cardiac electrophysiology (EP) procedures. However, fluoroscopy emits ionizing radiation which can lead to adverse health effects when exposed to in high doses (World Health Organization, 2016). Electroanatomic mapping (EAM) systems display the three-dimensional location of EP catheters and measure the local electrical activity of the heart. They can minimize a physician’s reliance on fluoroscopy and can help reduce radiation exposure during a case (Casella, 2011). EAM systems are diagnostic medical devices that inform the placement of ablation therapy and must accurately locate catheters to be deemed safe. Test methods to determine EAM system accuracy should be compared back to a gold standard, such as fluoroscopy. Fluoroscopy only provides a two-dimensional image of the catheter location, which is not a suitable ground truth for measuring the three-dimensional accuracy of EAM systems. X-Ray Reconstruction of Electrode Locations (XRROEL) calculates the true three-dimensional catheter location by performing a coordinate transform on two-dimensional fluoroscopy images. This thesis outlines the development and validation of the XRROEL method in a porcine animal model, and describes how XRROEL can be applied to optimize the location accuracy of electroanatomic mapping system algorithms.

<p> The thesis is concerned with the design and construction of an instrumentation system for a machine set in a power laboratory. As the system was designed primarily to replace conventional analog metering its operation is very easy to master given minimal instruction. The system is capable of measuring rotor speed, rotor angle and reactive torque. From these values mechanical power and slip are calculated. While acting as a measuring instrument the system can also simultaneously provide speed setting of a dc machine by means of a controlled rectifier. As this system is constructed around a microcomputer it is possible to expand some of the functions as well as interconnect to other digital devices for enhanced performance.</p> / Thesis / Master of Engineering (MEngr)

Software applications’ performance is hindered by a variety of factors, but most notably by the well-known CPU-memory speed gap (often known as the memory wall). This results in the CPU sitting idle waiting for data to be brought from memory to processor caches. The addressing used by caches cause non-uniform accesses to various cache sets. The non-uniformity is due to several reasons, including how different objects are accessed by the code and how the data objects are located in memory. Memory allocators determine where dynamically created objects are placed, thus defining addresses and their mapping to cache locations. It is important to evaluate how different allocators behave with respect to the localities of the created objects. Most allocators use a single attribute, the size, of an object in making allocation decisions. Additional attributes such as the placement with respect to other objects, or specific cache area may lead to better use of cache memories. In this dissertation, we proposed and implemented a framework that allows for the development and evaluation of new memory allocation techniques. At the root of the framework is a memory tracing tool called Gleipnir, which provides very detailed information about every memory access, and relates it back to source level objects. Using the traces from Gleipnir, we extended a commonly used cache simulator for generating detailed cache statistics: per function, per data object, per cache line, and identify specific data objects that are conflicting with each other. The utility of the framework is demonstrated with a new memory allocator known as equivalence class allocator. The new allocator allows users to specify cache sets, in addition to object size, where the objects should be placed. We compare this new allocator with two well-known allocators, viz., Doug Lea and Pool allocators.

Micro-Cooling, Heating and Power (CHP) is the decentralized generation of electricity in which normally wasted heat is recovered for use in heating and cooling of the space. A micro-CHP demonstration facility is needed to showcase the system and allow for experiments to be performed. This thesis illustrates the steps taken for the installation and instrumentation of a Micro-CHP (Cooling, Heating, and Power) demonstration facility. Equipment sizing was performed by creating an accurate building model and performing a transient building analysis. Temperature, pressure, flow rate, and relative humidity are measured in order to determine accurate energy balances through each piece of equipment in the micro-CHP system. The data is collected using a number of LabView subroutines while a Visual Basic program was developed to display the information.

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