Engineering Commons^™

Multi-Physical Study Of Mems Resonators And Oscillators, Xiaobo Guo

Electronic Theses and Dissertations

First, this research presents experimental and theoretical investigation of the response of micro scale dual-plate thermal-piezoresistive resonators (TPR) and self-sustained oscillators (TPO) to different gases and pressures. It is demonstrated that the resonant frequency of such devices follows particular trends in response to the changes in the surrounding gas and its pressure. A mathematical model has been derived to explain the damping dependent frequency shift characteristic of TPO. The solution of the model indicates that the stiffness of the actuator beam decreases as the value of damping coefficient drops at lower gas density caused by the change in the gas …

An Efficient Navigation-Control System For Small Unmanned Aircraft, Jonathan Alejandro Girwar-Nath

Electronic Theses and Dissertations

Unmanned Aerial Vehicles have been research in the past decade for a broad range of tasks and application domains such as search and rescue, reconnaissance, traffic control, pipe line inspections, surveillance, border patrol, and communication bridging.

This work describes the design and implementation of a lightweight Commercial-Off-The-Shelf (COTS) semi-autonomous Fixed-Wing Unmanned Aerial Vehicle (UAV). Presented here is a methodology for System Identification utilizing the Box-Jenkins model estimator on recorded flight data to characterize the system and develop a mathematical model of the aircraft. Additionally, a novel microprocessor, the XMOS, is utilized to navigate and maneuver the aircraft utilizing a PD …

Evaluation Of Novel High-Density Emg Feedback Parameters On The Spatial Distribution Of Trapezius Muscle Activity, Brecca M. Gaffney

Electronic Theses and Dissertations

Each year, 17.9% of adults working in a computer-dominated work environment develop an episode of chronic neck and shoulder pain. An effective treatment method for chronic pain is postural correction through therapist. The understanding of the relation between cervicoscapular posture and trapezius muscle activity is not fully understood because the anatomy of the scapula is not accessible for direct observation. Until recently, the spatial distribution of trapezius muscle activity could not be measured due to the limitation in size of detection zone in traditional bipolar electrodes. The primary goal of postural correction when treating cases of chronic neck and shoulder …

Finite Element Analysis Of Thermomechanical Processes In Disk Clutch Systems, Zhuo Chen

Electronic Theses and Dissertations

The engagement of clutch system is a typical dynamic coupled temperature-displacement process which contains two or more sliding surfaces involved in frictional contact. This process influences evidently the thermal fatigue, noise and vibration of the clutch system. This effect can be more remarkable if the temperature distribution over the clutch disk is not uniform.

This thesis is organized into five chapters:

The first chapter is an introduction which reviews the background and previous work of thermoelastic instability and finite element analysis of clutch system and disk brake.

A parametric analysis of TEI (thermoelastic instability) is elaborated in the second chapter. …

Galvanic Corrosion Of High-Temperature Low-Sag (Htls) High Voltage Conductors: New Materials—New Challenges, Eva Håkansson

Electronic Theses and Dissertations

High-Temperature Low-Sag (HTLS) high voltage overhead conductors offer higher operating temperatures, reduced resistance and less sag than conventional designs. With up to twice the current capacity for the same diameter conductor, they may help ease the power shortage in the constantly increasing electricity demand, but there might be some concerns about their corrosion resistance.

These new conductors use materials relatively new to the power industry, such as advanced carbon fiber polymer matrix composites and unique metal matrix composites/nano-composites predominantly used in aerospace industries. This study has made an initial assessment of potential galvanic corrosion problems in three very different HTLS …

Cavitation In Pharmaceutical Manufacturing And Shipping, Donn Sederstrom

Electronic Theses and Dissertations

Therapeutic proteins are used to successfully treat hemophilia, Crohn's Disease, diabetes, and cancer. Recent product recalls have occurred because of sub-visible particle formation resulting from the inherent instability of proteins. It has been suggested that particle formation is associated with late stage processing steps of filling, shipping, and delivery. Previous work at the University of Denver demonstrated that fluid cavitation can generate a large number of sub-visible protein particles in ultra clean formulations, but that mitigation can be achieved with fluid property manipulation. The goal of this research was to (1) assess the risk of cavitation under common pharmaceutical manufacturing …

Representing Intersubject Variability With A Statistical Shape And Alignment Model Of The Knee, Chandreshwar Rao

Electronic Theses and Dissertations

Prior statistical shape models have not considered multiple structures in the knee joint to characterize anatomic variation which are required to investigate joint mechanics further for the successful knee replacement. Accordingly, the study's objective was to develop statistical shape and alignment model (SSAM) to capture intersubject variability and demonstrate the ability to generate realistic instances for use in finite element analysis (FEA). SSAM described the variability in the training set of 20 subjects with a series of modes of variation obtained by performing principal component analysis (PCA). PCA produced modes of variation with the first 3 modes representing 70% and …

Generalizable Methods For Modeling Lumbar Spine Kinematics, Craig Joseph Simons

Electronic Theses and Dissertations

A more complete understanding of lumbar spine kinematics could improve diagnoses and treatment of low back pathologies and may advance the development of biomechanical models. Kinematics describes motion of the five lumbar vertebrae without consideration for the forces that cause the motion. Despite considerable attention from researchers and clinicians, lumbar spine kinematics are not fully understood because the anatomy is not accessible for direct observation and the complex governing biomechanics produce small magnitude, coupled intervertebral movements.

The overall goal of this project was to develop a descriptive model of intervertebral lumbar spine kinematics that is applicable to a generalizable subject …