Engineering Commons^™

Mems Capacitive Strain Sensing Elements For Integrated Total Knee Arthroplasty Prosthesis Monitoring, Boyd Mccutchen Evans Iii

Doctoral Dissertations

Measuring the in vivo load state of Total Knee Arthroplasty (TKA) components is required to understand the structural environment and wear characteristics of the devices. The ability to acquire this information gives tremendous insight into the mechanics of the joint replacement prosthesis. Data corresponding to normal loads, in-plane loads, shear loads, load center, contact area, and the rate of loading is needed to fully understand the kinematics and kinetics of the orthopedic implant. In this research, a novel sensing system has been developed which is capable of fully characterizing three-dimensional strain and stress at a single location.

Capacitance-based sensors were …

Streaming Effects In Liquid Injection Rocket Engines With Transverse Mode Oscillations, Sean Robert Fischbach

Doctoral Dissertations

This research is an analytical investigation of wave interactions in a simulated liquid rocket engine with uniform injection imposed at the faceplate. Of significant interest are the secondary nonlinear flows, particularly acoustic streaming, induced by transverse wave impingement over the engine injector surface. The corresponding cylindrical chamber has a small length-to-diameter ratio with respect to solid and hybrid rockets. Given their low chamber aspect ratios, liquid thrust engines are known to experience severe tangential and radial oscillation modes more often than longitudinal ones. Experimental evidence demonstrates the production of large peak-to-trough amplitude flow oscillations along with the development of a …

Laser Surface Structuring Of Alumina, Sandip Pundlikrao Harimkar

Doctoral Dissertations

Alumina ceramic is an important abrasive material for grinding wheels used for rough grinding/machining of materials in manufacturing industry. Purpose of this work is to explore laser surface structuring of alumina grinding wheels for precision machining/grinding of materials by modifying surface microstructure of wheels. Major objective of this work is to study the evolution of surface microstructure and depth of modification such that microstructures/properties of modified wheels can be efficiently tailored based on fundamental understanding of physical processes taking place during laser surface structuring.

Surface structuring of alumina using a continuous wave Nd:YAG laser resulted in significant surface melting and …

Optimal Sizing And Location Of Static And Dynamic Reactive Power Compensation, Wenjuan Zhang

Doctoral Dissertations

The key of reactive power planning (RPP), or Var planning, is the optimal allocation of reactive power sources considering location and size. Traditionally, the locations for placing new Var sources were either simply estimated or directly assumed. Recent research works have presented some rigorous optimization-based methods in RPP. Different constraints are the key of various optimization models, identified as Optimal Power Flow (OPF) model, Security Constrained OPF (SCOPF) model, and Voltage Stability Constrained OPF model (VSCOPF).

First, this work investigates the economic benefits from local reactive power compensation including reduced losses, shifting reactive power flow to real power flow, and …

Electro-Thermal Modeling Of Sic Power Electronic Systems, Hui Zhang

Doctoral Dissertations

As the development of Silicon (Si) semiconductor technology slows down due to its material limitations, more and more attention is being paid to wide bandgap material based semiconductor technology. Silicon Carbide (SiC) has been widely recognized as the material for next generation power electronic devices. However, a great deal of work needs to be done before SiC power devices can be widely applied. This dissertation addresses this need and has conducted research on the modeling of SiC power electronic system. More specifically, a method for system modeling of a SiC power system based on basic physics and device tests is …

Yield And Reliability Analysis For Nanoelectronics, Tao Yuan

Doctoral Dissertations

As technology has continued to advance and more break-through emerge, semiconductor devices with dimensions in nanometers have entered into all spheres of our lives. Accordingly, high reliability and high yield are very much a central concern to guarantee the advancement and utilization of nanoelectronic products. However, there appear to be some major challenges related to nanoelectronics in regard to the field of reliability: identification of the failure mechanisms, enhancement of the low yields of nano products, and management of the scarcity and secrecy of available data [34]. Therefore, this dissertation investigates four issues related to the yield and reliability of …

Time And Frequency Domain Analyses Of Hydrologic And Stream Water Quality Data, Shesh Raj Koirala

Doctoral Dissertations

The issue of scaling of deterministic properties at various domain levels has become an area of interest for active research. Interpretation of observational data, and similarly hydrologic simulation, require an understanding of how certain deterministic modeling parameters scale from the smaller to larger domains spatially and temporally. Novel approaches to better understand scaling behavior in hydrologic systems and that will result in improved deterministic modeling are necessary to advance the state-of-the-science in hydrologic transport processes, particularly in the areas of microbial concentration and inorganic chemical constituent dynamics. Two primary objectives of this research were i) to determine the statistical relationship …

Evaluation Of Impacts On Delay, Cycle-Length Optimization, Control Types, And Peak-Hour Factor With The Randomness Of Traffic, Jan-Mou Li

Doctoral Dissertations

Some basic concepts about traffic which are correct in theory may be misinterpreted in practice. Such misinterpretations may lead to a different direction from the ideal operation. This four-part dissertation is designated to examine fundamental concepts in traffic operation, and to validate the impact of randomness on control delays, cycle-length optimization, control types, and the peak-hour factor.

Control delays experienced by drivers is a critical performance measure on interrupted-flow traffic which involves movements at slower speeds and stops on intersection approaches, as vehicles move up in the queue or slow down upstream of an intersection. Since the basic term of …

Investigation Of Vorticity Confinement As A High Reynolds Number Turbulence Model, Nicholas F. Lynn

Doctoral Dissertations

Vorticity Confinement (VC) is a computational technique used to compute fluid flows with thin vortical regions in an accurate and efficient manner. Recent results have shown that it accurately computes the turbulent wake behind blunt bodies at large Reynolds numbers. Physically, these flows are dominated by thin vortices that convect downstream with the flow, which accounts for the important higher-order velocity statistics. These thin vortices are artificially dissipated with traditional methods, whereas VC can accurately compute them.

VC consists of a set of discrete equations with the confinement appearing as a source term in the discretized momentum equations. The term …

Fabric-On-A-Chip: Toward Consolidating Packet Switching Functions On Silicon, William B. Matthews

Doctoral Dissertations

The switching capacity of an Internet router is often dictated by the memory bandwidth required to bu¤er arriving packets. With the demand for greater capacity and improved service provisioning, inherent memory bandwidth limitations are encountered rendering input queued (IQ) switches and combined input and output queued (CIOQ) architectures more practical. Output-queued (OQ) switches, on the other hand, offer several highly desirable performance characteristics, including minimal average packet delay, controllable Quality of Service (QoS) provisioning and work-conservation under any admissible traffic conditions. However, the memory bandwidth requirements of such systems is O(NR), where N denotes the number of …

Stochastic Signal Processing And Power Control For Wireless Communication Systems, Mohammed Mohsen Olama

Doctoral Dissertations

This dissertation is concerned with dynamical modeling, estimation and identification of wireless channels from received signal measurements. Optimal power control algorithms, mobile location and velocity estimation methods are developed based on the proposed models.

The ultimate performance limits of any communication system are determined by the channel it operates in. In this dissertation, we propose new stochastic wireless channel models which capture both the space and time variations of wireless systems. The proposed channel models are based on stochastic differential equations (SDEs) driven by Brownian motions. These models are more realistic than the time invariant models encountered in the literature …

Novel Numerical Approaches For The Resolution Of Direct And Inverse Heat Transfer Problems, Gregory Evan Osborne

Doctoral Dissertations

This dissertation describes an innovative and robust global time approach which has been developed for the resolution of direct and inverse problems, specifically in the disciplines of radiation and conduction heat transfer.

Direct problems are generally well-posed and readily lend themselves to standard and well-defined mathematical solution techniques. Inverse problems differ in the fact that they tend to be ill-posed in the sense of Hadamard, i.e., small perturbations in the input data can produce large variations and instabilities in the output. The stability problem is exacerbated by the use of discrete experimental data which may be subject to substantial measurement …

Image Segmentation Using Pde, Variational, Morphological And Probabilistic Methods, Yongsheng Pan

Doctoral Dissertations

The research in this dissertation has focused upon image segmentation and its related areas, using the techniques of partial differential equations, variational methods, mathematical morphological methods and probabilistic methods. An integrated segmentation method using both curve evolution and anisotropic diffusion is presented that utilizes both gradient and region information in images. A bottom-up image segmentation method is proposed to minimize the Mumford-Shah functional. Preferential image segmentation methods are presented that are based on the tree of shapes in mathematical morphologies and the Kullback-Leibler distance in information theory. A thorough evaluation of the morphological preferential image segmentation method is provided, and …

Design Of A Cost-Efficient Reconfigurable Pipeline Adc, Wenchao Qu

Doctoral Dissertations

Power budget is very critical in the design of battery-powered implantable biomedical instruments. High speed, high resolution and low power usually cannot be achieved at the same time. Therefore, a tradeoff must be made to compromise every aspect of those features. As the main component of the bioinstrument, high conversion rate, high resolution ADC consumes most of the power. Fortunately, based on the operation modes of the bioinstrument, a reconfigurable ADC can be used to solve this problem. The reconfigurable ADC will operate at 10-bit 40 MSPS for the diagnosis mode and at 8-bit 2.5 MSPS for the monitor mode. …

Automated Genome-Wide Protein Domain Exploration, Bhanu Prasad Rekepalli

Doctoral Dissertations

Exploiting the exponentially growing genomics and proteomics data requires high quality, automated analysis. Protein domain modeling is a key area of molecular biology as it unravels the mysteries of evolution, protein structures, and protein functions. A plethora of sequences exist in protein databases with incomplete domain knowledge. Hence this research explores automated bioinformatics tools for faster protein domain analysis. Automated tool chains described in this dissertation generate new protein domain models thus enabling more effective genome-wide protein domain analysis. To validate the new tool chains, the Shewanella oneidensis and Escherichia coli genomes were processed, resulting in a new peptide domain …

A Finite Element Study Of The Contact Stiffness Of Homogenous Materials And Thin Films, Haitao Xu

Doctoral Dissertations

The applicability of the stiffness equation S=2E_ra to elastic and elastic-plastic homogeneous materials and thin films on substrates is studied by finite element techniques. It is found that the stiffness equation works well in all these materials provided that a correction factor β is included. For elastic homogenous materials, the correction factor is examined for different friction conditions, Poisson’s ratios, and indenter cone angles. In the case of elastic-plastic indentation with a 70.3° cone, the correction factor is very close to that for elastic indentation of a matching conical hole, which provides a convenient way to model the …

Processing And Phase Formation In Zr-Based Bulk-Metallic Glass-Forming Alloys, James Joseph Wall

Doctoral Dissertations

Bulk-metallic glasses have established a formidable presence in the scientific community in recent years, due to a number of properties that are uncharacteristic of metallically-bonded materials. One of the fundamental challenges facing researchers in this field is to develop new and improved processing methods with the ultimate goal of facilitating a large-scale industrial integration of the materials.

The research described herein is directed toward the pursuit of developing and improving upon the current state-of-the art in the science of bulk-metallic glass processing. A number of research and development projects were undertaken in this pursuit. First, the technology to process bulk-metallic …

Degradation Mechanism Of Expanded Polystyrene (Eps) Foam In Lost Foam Casting, Pips Approach For Synthesis And Novel Expansion Techniques For Cellular Foam, Indraneel Sen

Doctoral Dissertations

Lost Foam Casting (LFC) is a metal casting technology that facilitates fabrication of near-net shape metal castings using expanded polystyrene (EPS) foam patterns that are coated with refractory slurry and is effective for producing aluminum or iron castings of complicated geometry. However, the LFC process can produce considerable amount of scrap due to casting defects. Removing the EPS thermal decomposition products through the ceramic coating ahead of the advancing metal front during the liquid metal pour is a key factor in obtaining a defect free casting. Developing a fundamental understanding of foam degradation mechanism is essential in improving LFC process. …

A Study Of Indentation Creep Using The Finite Element Method, Sangjoon Sohn

Doctoral Dissertations

Indentation is a useful technique for studying the mechanical properties of a material. Measurable mechanical properties from indentation include time-dependent as well as time independent properties. Among these mechanical properties, time-dependent permanent deformation (creep) is of interest in this study. The purpose of this study is to explore the behavior of creep deformation of a solid under indentation. The main scientific research tool will be the finite element method.

Existing works by others provide limited solutions that allow us to correlate uniaxial creep to indentation creep. In this study, the task is taken a step further to enhance and modify …

A Generic Prognostic Framework For Remaining Useful Life Prediction Of Complex Engineering Systems, Alexander V. Usynin

Doctoral Dissertations

Prognostics and Health Management (PHM) is a general term that encompasses methods used to evaluate system health, predict the onset of failure, and mitigate the risks associated with the degraded behavior. Multitudes of health monitoring techniques facilitating the detection and classification of the onset of failure have been developed for commercial and military applications. PHM system designers are currently focused on developing prognostic techniques and integrating diagnostic/prognostic approaches at the system level. This dissertation introduces a prognostic framework, which integrates several methodologies that are necessary for the general application of PHM to a variety of systems. A method is developed …

Theoretical Modeling And Experimental Validation Of In Vivo Mechanics For Subjects Having Variable Cervical Spine Conditions, Fei Liu

Doctoral Dissertations

The objective of this study was to use the state-of-art 3D-to-2D registration technologies including fluoroscopic, CT and MRI methods to analyze 2D and 3D in vivo kinematics of the whole cervical spine under variable conditions; and use inverse dynamic model based on Kane’s dynamics to predict their 2D and 3D in vivo interactive contact and muscular forces. Totally, forty patients (ten having normal cervical spines, ten having degenerative cervical spines, ten having anterior cervical decompression and fusion (ACDF), and ten having cervical artificial disc replacement (CADR)) were enrolled into 2D study and three patients (one having normal cervical spines, one …

Self-Certified Public Key Cryptographic Methodologies For Resource-Constrained Wireless Sensor Networks, Ortal Arazi

Doctoral Dissertations

As sensor networks become one of the key technologies to realize ubiquitous computing, security remains a growing concern. Although a wealth of key-generation methods have been developed during the past few decades, they cannot be directly applied to sensor network environments. The resource-constrained characteristics of sensor nodes, the ad-hoc nature of their deployment, and the vulnerability of wireless media pose a need for unique solutions.

A fundamental requisite for achieving security is the ability to provide for data con…dential- ity and node authentication. However, the scarce resources of sensor networks have rendered the direct applicability of existing public key cryptography …

Characterization Of A Biomimetic Calcium-Deficient Hydroxyapatite-Bacterial Cellulose Composite, Stacy Hutchens

Doctoral Dissertations

Bone is the second most implanted tissue next to blood causing approximately 2.2 million people to receive bone grafts each year. Developing safe synthetic bone grafts allows quick and safe restoration of bone function while avoiding the surgical risks associated with bone autografting (self donation), and risks of disease transmission and immunogenic response associated with allografts (bone donated from other humans) and xenografts (grafts derived from animal tissue). This dissertation entails the study and development of a novel potential synthetic bone graft consisting of a composite of calcium-deficient hydroxyapatite (CdHAP) biomimetically deposited in a bacterial cellulose (BC) hydrogel.

To determine …

A Study Of The Secondary Electrons, Yinghong Lin

Doctoral Dissertations

Slow secondary electrons (SEs) (E<50 eV) are those emitted from a sample as the result of bombardment by energetic particles. They are the most important signal source for SEM and for other advanced microanalysis techniques. SE yield δ and spectrum N(E) are the two important parameters evaluating the capability of a sample on producing SEs and the energy distribution of SEs generated from the sample respectively. Measuring δ and N(E) is not easy since SEs are easily affected by sample surface condition and by experimental configuration. Though SE has been studied since its first find in 1902, experimental date of it are inconsistent and unsystematic. Theoretical models on the SE production are not well established.

To better understand the secondary electrons, an optimization of a scattered experimental SE yield database was carried out by fitting the data to a semi-empirical universal curve and by a Monte Carlo simulation. The profiles of SE yield versus beam energy and the values of SE excitation energyε and mean SE escape depthλ were generated for 44 elements. An atomic shell filling effect was found on the maximum SE yields and the corresponding beam energies.

To obtain more accurate and systematic SE yield data, a novel experimental method by collecting electron spectra on an AES …

Synthesis And Structure Of Li6Y(Bo3)3 As A Neutron Scintillator, Emily Ann Sheats

Masters Theses

Single phase polycrystalline Li₆Y(BO₃)₃:Ce has been produced with substitutions of Ca, Sc, La, Sr, Gd, and Lu substituting for Y. Samples included isotopes of 6-Li and 11-B through isotopically enriched Li₂CO₃ and H₃BO₃. X-ray powder diffraction was used to verify the phase(s) present, while Rietveld refinements provided lattice parameters. Photoluminescence data were collected to verify Ce activation and proper location within the crystal structure. The amount of Ce and Ca were then varied to survey the best composition for scintillation properties within Li₆Y(BO₃) …

Development Of The Telemetrical Intraoperative Soft Tissue Tension Monitoring System In Total Knee Replacement With Mems And Asic Technologies, Gary To

Masters Theses

The alignment of the femoral and tibial components of the Total Knee Arthoplasty (TKA) is one of the most important factors to implant survivorship. Hence, numerous ligament balancing techniques and devices have been developed in order to accurately balance the knee intra-operatively. Spacer block, tensioner and tram adapter are instruments that allow surgeons to qualitatively balance the flexion and extension gaps during TKA. However, even with these instruments, the surgical procedure still relies on the skill and experience of the surgeon. The objective of this thesis is to develop a computerized surgical instrument that can acquire intra-operative data telemetrically for …

Virtual Modeling And Verification Of Air-Ride Truck Seat Using Multibody Dynamics For Whole Body Vibration Evaluation, Devdutt Nandkishore Shende

Masters Theses

To aid the tuning and optimization of the truck seat design to specific trucks and road profiles during the design phase, this study presents the development and validation of a virtual seat model. This study also assess the utility of the model for whole body vibrations evaluation.

The virtual dynamic seat model was developed in MSC. ADAMS/VIEW. The critical elements like the suspension mechanism, the airspring, dampers and seat cushion were modeled using tested data. To validate the performance of the virtual model, prototype tests were performed using the MTS 6-axis simulator. The modeling process was targeted to achieve a …

Impedance Matching And PspiceR Simulation Of One Atmosphere Uniform Glow Discharge Plasma (Oaugdp™) Reactor/Actuator Systems, Zhiyu Chen

Masters Theses

This thesis addresses two important issues relevant to One Atmosphere Uniform Glow Discharge Plasma (OAUGDP™) reactors and actuators ¾ impedance matching and PSpice^R simulation.

An OAUGDP™ reactor/actuator with the plasma energized can be modeled as a capacitor in parallel with a resistor. In addition, the non-ideality of the transformer between the RF power supply and the plasma reactor/actuator introduces an imaginary component in its impedance. Thus, the load of the RF power supply, as seen by its output terminals, is highly reactive. An impedance mismatch resulting from the absence of a matching network will cause a large reflected power …

A Standard Cmos Compatible Bandgap Voltage Reference With Post-Process Digitally Tunable Temperature Coefficient, Sam D. Caylor

Masters Theses

An essential element of most robust analog/mixed-signal systems is a stable and precise bandgap voltage reference (BGR). CMOS compatible BGR circuits are generally limited by variability in output drift over temperature due to process variations. In this work a CMOS BGR is developed that provides simple, digitally-controlled post-process (i.e., post fabrication) trimming. The trimming is achieved through MOSFET switches used to adjust a current gain factor for the thermal voltage referenced current within the BGR circuit. This current is proportional to absolute temperature (PTAT). The PTAT current is injected into a series connected resistor and diode to ultimately provide an …

The Detection Of Stress Corrosion Cracking In Natural Gas Pipelines Using Electromagnetic Acoustic Transducers, Austin P. Albright

Masters Theses

This thesis describes the refinement of a non-destructive, in-line inspection system sensor for the detection of stress corrosion cracks (SCCs) in natural gas pipelines. The sensors are prototype electromagnetic acoustic transducers (EMATs) for noncontact ultrasonic inspection. The focus areas discussed involve the statistically validated performance improvements achieved through the addition of 12 more features, the addition of Principal Component Analysis plus Linear Discriminant Analysis (PCA+LDA) to the classification algorithm, and most significantly the creating of a training set. The training set allowed PCA+LDA to be included in the classification algorithm, as well as allowing one set of no-flaw signature features, …