Engineering Commons^™

Noninvasive Assessment Of Photoreceptor Structure And Function In The Human Retina, Robert Francis Cooper

Dissertations (1934 -)

The human photoreceptor mosaic underlies the first steps of vision; thus, even subtle defects in the mosaic can result in severe vision loss. The retina can be examined directly using clinical tools; however these devices lack the resolution necessary to visualize the photoreceptor mosaic. The primary limiting factor of these devices is the optical aberrations of the human eye. These aberrations are surmountable with the incorporation of adaptive optics (AO) to ophthalmoscopes, enabling imaging of the photoreceptor mosaic with cellular resolution. Despite the potential of AO imaging, much work remains before this technology can be translated to the clinic. Metrics …

Anaerobic Membrane Bioreactors To Treat Municipal Wastewater At Ambient Temperatures, Matthew D. Seib

Dissertations (1934 -)

Anaerobic biotechnology is viewed as a sustainable alternative to aerobic biotechnology for municipal wastewater recovery. However, anaerobic processes have not been successful in cold climates. Past examples have not been able to meet low organic effluent concentrations, or have failed due to biomass washout resulting from low temperature operation and short hydraulic residence time. Recently, the anaerobic membrane bioreactor (AnMBR) has been shown to achieve low effluent organic concentrations and maintain stable anaerobic biomass. However, shortcomings have included high energy demands for membrane operation and poor understanding of microbial community structures within AnMBRs. This dissertation describes efforts to improve AnMBRs …

Health Condition Monitoring And Fault-Tolerant Operation Of Adjustable Speed Drives, Jiangbiao He

Dissertations (1934 -)

Adjustable speed drives (ASDs) have been extensively used in industrial applications over the past few decades because of their benefits of energy saving and control flexibilities. However, the wider penetration of ASD systems into industrial applications is hindered by the lack of health monitoring and fault-tolerant operation techniques, especially in safety-critical applications. In this dissertation, a comprehensive portfolio of health condition monitoring and fault-tolerant operation strategies is developed and implemented for multilevel neutral-point-clamped (NPC) power converters in ASDs. Simulations and experiments show that these techniques can improve power cycling lifetime of power transistors, on-line diagnosis of switch faults, and fault-tolerant …

The Contribution Of Syntrophic Fatty-Acid Degrading Microbial Communities To Anaerobic Digester Function And Stability, Prince Peter Mathai

Dissertations (1934 -)

Anaerobic digestion (AD), the conversion of complex organic matter to methane, occurs through a series of reactions mediated by different guilds of microorganisms. AD process imbalances, such as organic overload or high organic loading rates (OLR), can result in the accumulation of volatile fatty acids (VFA) e.g., propionate, which must be degraded to maintain stable reactor function. VFAs are metabolized by syntrophic fatty-acid degrading bacteria (SFAB) in association with methanogenic archaea (collectively, syntrophic microbial communities, SMC). Despite their indispensable role in AD, little is known about the ecology of SFAB, especially under stressed conditions. To facilitate ecological studies, four quantitative …

Biomechanics Of Pediatric Manual Wheelchair Mobility, Brooke A. Slavens, Alyssa J. Schnorenberg, Christine M. Aurit, Sergey Tarima, Lawrence C. Vogel, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Currently, there is limited research of the biomechanics of pediatric manual wheelchair mobility. Specifically, the biomechanics of functional tasks and their relationship to joint pain and health is not well understood. To contribute to this knowledge gap, a quantitative rehabilitation approach was applied for characterizing upper extremity biomechanics of manual wheelchair mobility in children and adolescents during propulsion, starting, and stopping tasks. A Vicon motion analysis system captured movement, while a SmartWheel simultaneously collected three-dimensional forces and moments occurring at the handrim. A custom pediatric inverse dynamics model was used to evaluate three-dimensional upper extremity joint motions, forces, and moments …

Integrating Distributed Sources Of Information For Construction Cost Estimating Using Semantic Web And Semantic Web Service Technologies, Mehrdad Niknam, Saeed Karshenas

Civil and Environmental Engineering Faculty Research and Publications

A construction project requires collaboration of several organizations such as owner, designer, contractor, and material supplier organizations. These organizations need to exchange information to enhance their teamwork. Understanding the information received from other organizations requires specialized human resources. Construction cost estimating is one of the processes that requires information from several sources including a building information model (BIM) created by designers, estimating assembly and work item information maintained by contractors, and construction material cost data provided by material suppliers. Currently, it is not easy to integrate the information necessary for cost estimating over the Internet.

This paper discusses a new …

Opportunities To Identify Unmet Needs Outside Of The Operating Room, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

The ability to identify unmet needs and new product opportunities is an important skill for biomedical engineering students planning a career in the medical device industry. Most biomedical engineering graduates will work in industry where many projects will not be defined for them. They will need to work with physicians, surgeons, nurses, clinical engineers, and other users of medical technology to identify problems and unmet needs and will work closely with marketing, sales, and other personnel to identify new product development opportunities. Students will be better prepared for careers involving the development of new medical devices if they are able …

Error Probabilities For Optical Receivers That Employ Dynamically Biased Avalanche Photodiodes, Georges El-Howayek, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

A novel theory was recently reported for the avalanche multiplication process in avalanche photodiodes (APDs) under dynamic reverse-biasing conditions. It has been shown theoretically that the bit-synchronized, periodic modulation of the electric field in the multiplication region can offer improvements in the gain-bandwidth product by reducing intersymbol interference in optical receivers. This paper reports a rigorous formulation of the sensitivity of optical receivers that employ dynamically biased APDs. To enable the sensitivity analysis, a recurrence theory is developed to calculate the joint probability distribution function (PDF) of the stochastic gain and avalanche buildup time in APDs that are operated under …

Impaired Regulation Post-Stroke Of Motor Unit Firing Behavior During Volitional Relaxation Of Knee Extensor Torque Assessed Using High Density Surface Emg Decomposition, Spencer A. Murphy, Reivian Berrios, P. Andrew Nelson, Francesco Negro, Dario Farina, Brian D. Schmit, Allison Hyngstrom

Physical Therapy Faculty Research and Publications

The purpose of this study was to use high density surface EMG recordings to quantify stroke-related abnormalities in motor unit firing behavior during repeated sub-maximal knee extensor contractions. A high density surface EMG system (sEMG) was used to record and extract single motor unit firing behavior in the vastus lateralis muscle of 6 individuals with chronic stroke and 8 controls during repeated sub-maximal isometric knee extension contractions. Paretic motor unit firing rates were increased with subsequent contractions (6.19±0.35 pps vs 7.89±0.66 pps, P

Stretch‐Induced Increase In Cardiac Contractility Is Independent Of Myocyte Ca2+ While Block Of Stretch Channels By Streptomycin Improves Contractility After Ischemic Stunning, Samhita S. Rhodes, Amadou Ks Camara, Mohammed Aldakkak, James S. Heisner, David F. Stowe

Biomedical Engineering Faculty Research and Publications

Stretching the cardiac left ventricle (LV) enhances contractility but its effect on myoplasmic [Ca²⁺] is controversial. We measured LV pressure (LVP) and [Ca²⁺] as a function of intra-LV stretch in guinea pig intact hearts before and after 15 min global stunning ± perfusion with streptomycin (STM), a stretch activated channel blocker. LV wall [Ca²⁺] was measured by indo-1 fluorescence and LVP by a saline-filled latex balloon inflated in 50 μL steps to stretch the LV. We implemented a mathematical model to interpret crossbridge dynamics and myofilament Ca²⁺ responsiveness from the instantaneous relationship between …

Using Swing Resistance And Assistance To Improve Gait Symmetry In Individuals Post-Stroke, Sheng-Che Yen, Brian D. Schmit, Ming Wu

Biomedical Engineering Faculty Research and Publications

A major characteristic of hemiplegic gait observed in individuals post-stroke is spatial and temporal asymmetry, which may increase energy expenditure and the risk of falls. The purpose of this study was to examine the effects of swing resistance/assistance applied to the affected leg on gait symmetry in individuals post-stroke. We recruited 10 subjects with chronic stroke who demonstrated a shorter step length with their affected leg in comparison to the non-affected leg during walking. They participated in two test sessions for swing resistance and swing assistance, respectively. During the adaptation period, subjects counteracted the step length deviation caused by the …

Validation Of A Finite Element Model Of The Humerus For Fracture Risk Assessment During Assisted Ambulation, Jessica M. Fritz, Prateek Grover, Nicole M. Grosland, Carolyne Albert, Linda M. Mcgrady, Mei Wang, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Finite Element Assessment Of Pediatric Femoral Response To Loading During Ambulation: Normal Vs. Osteogenesis Imperfecta (Oi) Bone, Jessica M. Fritz, Carolyne Albert, Nicole M. Grosland, Peter A. Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Survivable Cloud Network Mapping For Disaster Recovery Support, Feng Gu, Khaled B. Shaban, Nasir Ghani, Samee Khan, Mahshid R. Naeini, Majeed M. Hayat, Chadi Assi

Electrical and Computer Engineering Faculty Research and Publications

Network virtualization is a key provision for improving the scalability and reliability of cloud computing services. In recent years, various mapping schemes have been developed to reserve VN resources over substrate networks. However, many cloud providers are very concerned about improving service reliability under catastrophic disaster conditions yielding multiple system failures. To address this challenge, this work presents a novel failure region-disjoint VN mapping scheme to improve VN mapping survivability. The problem is first formulated as a mixed integer linear programming problem and then two heuristic solutions are proposed to compute a pair of failure region-disjoint VN mappings. The solution …

Improved Terahertz Modulation Using Germanium Telluride (Gete) Chalcogenide Thin Films, A. H. Gwin, C. H. Kodama, T. Laurvick, Ronald A. Coutu Jr., P. F. Taday

Electrical and Computer Engineering Faculty Research and Publications

We demonstrate improved terahertz (THz) modulation using thermally crystallized germanium telluride (GeTe) thin films. GeTe is a chalcogenidematerial that exhibits a nonvolatile, amorphous to crystalline phase change at approximately 200 °C, as well as six orders of magnitude decreased electrical resistivity. In this study, amorphous GeTe thin filmswere sputtered on sapphire substrates and then tested using THz time-domain spectroscopy (THz-TDS). The test samples, heated in-situ while collecting THz-TDS measurements, exhibited a gradual absorbance increase, an abrupt nonvolatile reduction at the transition temperature, followed by another gradual increase in absorbance. The transition temperature was verified by conducting similar thermal tests while …

Design And Characterization Of A Low Cost Mems Imu Cluster For Precision Navigation, Daniel R. Greenheck

Master's Theses (2009 -)

The fast paced development of micro-electromechanical systems (MEMS) technology in recent years has resulted in the availability of low cost gyroscopes and accelerometers in commercial markets. These sensors can be integrated into a single device known as an inertial measurement unit (IMU). An IMU is capable of tracking and navigating a vehicle for a short period of time in the absence of external position and attitude updates. The precision of the manufacturing techniques used to fabricate commercial MEMS sensors as well as their mechanical nature result in noise and errors that limit their performance. It has been mathematically shown that …

Ecohydrological Modeling In Agroecosystems: Examples And Challenges, Amilcare Porporato, X. Feng, S. Manzoni, Y. Mau, Anthony J. Parolari, G. Vico

Civil and Environmental Engineering Faculty Research and Publications

Human societies are increasingly altering the water and biogeochemical cycles to both improve ecosystem productivity and reduce risks associated with the unpredictable variability of climatic drivers. These alterations, however, often cause large negative environmental consequences, raising the question as to how societies can ensure a sustainable use of natural resources for the future. Here we discuss how ecohydrological modeling may address these broad questions with special attention to agroecosystems. The challenges related to modeling the two‐way interaction between society and environment are illustrated by means of a dynamical model in which soil and water quality supports the growth of human …

Addressing Uncertainty In Ensemble Sea-Level Rise Predictions, Matthew A. Thomas, Ting Lin

Civil and Environmental Engineering Faculty Research and Publications

Sea-level rise represents a looming hazard to coastal communities which remains difficult to quantify. Ensemble climate change predictions incorporate epistemic uncertainty in the climate modeling process and climate forcing scenarios help portray a range of radiative forcing changes. This study proposes a method for incorporating both model and scenario uncertainty in ensemble projections of thermosteric sea-level rise. A Markov Chain Monte Carlo algorithm is utilized to weigh the contributions of eight process-based climate models as well as the four Representative Concentration Pathways based on convergence criteria and observational data. Hazard analysis and deaggregation combine these contributions over a range of …

The Doomsday Equation And 50 Years Beyond: New Perspectives On The Human-Water System, Anthony J. Parolari, Gabriel Katul, Amilcare Porporato

Civil and Environmental Engineering Faculty Research and Publications

In 1960, von Foerster et al. humorously predicted an abrupt transition in human population growth to occur in the mid‐21st century. Their so‐called ‘Doomsday’ emerged from either progressive degradation of a finite resource or faster‐than‐exponential growth of an increasingly resource‐use efficient population, though what constitutes this resource was not made explicit. At present, few dispute the claim that water is the most fundamental resource to sustainable human population growth. Multiple lines of evidence demonstrate that the global water system exhibits nontrivial dynamics linked to similar patterns in population growth. Projections of the global water system range from a finite carrying …

Vocal Classification Of Vocalizations Of A Pair Of Asian Small-Clawed Otters To Determine Stress, Peter M. Scheifele, Michael T. Johnson, Michelle Fry, Benjamin Hamel, Kathryn Laclede

Electrical and Computer Engineering Faculty Research and Publications

Asian Small-Clawed Otters (Aonyx cinerea) are a small, protected but threatened species living in freshwater. They are gregarious and live in monogamous pairs for their lifetimes, communicating via scent and acoustic vocalizations. This study utilized a hidden Markov model (HMM) to classify stress versus non-stress calls from a sibling pair under professional care. Vocalizations were expertly annotated by keepers into seven contextual categories. Four of these—aggression, separation anxiety, pain, and prefeeding—were identified as stressful contexts, and three of them—feeding, training, and play—were identified as non-stressful contexts. The vocalizations were segmented, manually categorized into broad vocal type call types, and analyzed …

Establishing The Relative Merits Of Interior And Spoke-Type Permanent-Magnet Machines With Ferrite Or Ndfeb Through Systematic Design Optimization, Peng Zhang, Gennadi Y. Sizov, Dan M. Ionel, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

In this paper, a multiobjective design optimization method combining design-of-experiments techniques and differential-evolution algorithms is presented. The method was implemented and utilized in order to provide practical engineering insights for the optimal design of interior and spoke-type permanent-magnet machines. Two combinations with 12 slots and 8 poles and 12 slots and 10 poles, respectively, have been studied in conjunction with rare-earth neodymium-iron-boron (NdFeB) and ferrites. As part of the optimization process, a computationally efficient finite-element electromagnetic analysis was employed for estimating the performance of thousands of candidate designs. Three optimization objectives were concurrently considered for minimum total material cost, power …

Biplanar Fluoroscopic Analysis Of In Vivo Hindfoot Kinematics During Ambulation, Janelle Ann Cross

Dissertations (1934 -)

The overall goal of this project was to develop and validate a biplanar fluoroscopic system and integrated software to assess hindfoot kinematics. Understanding the motion of the foot and ankle joints may lead to improved treatment methods in persons with foot and ankle pathologies. During gait analysis, skin markers are placed on the lower extremities, which are defined as four rigid-body segments with three joints representing the hip, knee and ankle. This method introduces gross assumptions on the foot and severely limits the analysis of in depth foot mechanics. Multi-segmental models have been developed, but are susceptible to skin motion …

Common Mode Voltage Mitigation Strategies Using Pwm In Neutral-Point-Clamped Multilevel Inverters, Chad Alexander Somogyi

Master's Theses (2009 -)

Over the last several decades, there has been consistent growth in the research and development of multilevel voltage-source inverter-based adjustable speed motor drives (ASDs) as a result of low cost, high reliability power semiconductors. The three-level neutral-point-clamped (NPC) ASD is a popular multilevel inverter used in low and medium voltage applications because of its ability to produce lower levels of total harmonic distortion (THD) and withstand higher voltages while preserving the rated output power compared to two-level ASDs. As with other voltage-source inverters, three-level NPC ASDs produce common-mode voltage (CMV) that can cause motor shaft voltages, bearing currents, and excess …

Converting Medical Service Provider Data Into A Unified Format For Processing, Brandon Krugman

Master's Theses (2009 -)

Most organizations process flat files regularly. There are different options for processing files, including SQL Server Integration Services (SSIS), BizTalk, SQL import job, and other Extract, Transform, and Load (ETL) processes. All of these options have very strict requirements for file formats. If the format of the file changes, all of these options throw a catastrophic error, and implementing a fix to handle the new format is difficult. With each of the methods, the new format needs to be configured in the development environment, and the data flow must be modified to process all of the changes. Due to the …

Municipal Wastewater Anaerobic Treatment With Enhanced Clarification, Kevin Berg

Master's Theses (2009 -)

As energy costs rise, water reclamation facilities (WRFs) desire lower cost, easily operated systems to remove BOD5 and suspended solids. WRFs typically utilize an aerobic process called activated sludge to remove biochemical oxygen demand (BOD). BOD, specifically 5 day BOD (BOD5), is used as an indicator of the organic strength of a solution. Anaerobic treatment provides an alternative to activated sludge by removing BOD5, generating biogas containing methane for energy and producing less biomass that requires disposal. Anaerobic treatment functions as an exceptional alternative to activated sludge when packaged as a system with a small footprint that operates at ambient …

Gene Expression In Experimental Aortic Coarctation And Repair: Candidate Genes For Therapeutic Intervention?, John F. Ladisa Jr., Serdar Bozdag, Jessica Olson, Ramani Ramchandran, Judy R. Kersten, Thomas J. Eddinger

Biomedical Engineering Faculty Research and Publications

Coarctation of the aorta (CoA) is a constriction of the proximal descending thoracic aorta and is one of the most common congenital cardiovascular defects. Treatments for CoA improve life expectancy, but morbidity persists, particularly due to the development of chronic hypertension (HTN). Identifying the mechanisms of morbidity is difficult in humans due to confounding variables such as age at repair, follow-up duration, coarctation severity and concurrent anomalies. We previously developed an experimental model that replicates aortic pathology in humans with CoA without these confounding variables, and mimics correction at various times using dissolvable suture. Here we present the most comprehensive …

Reply To “Perception Of Lower Extremity Loading In Stroke”, Virginia W. Chu, T. George Hornby, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Machine Design Experiments Using Gears To Foster Discovery Learning, Jonathon Earl Slightam, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

Machine Design Experiments Using Gears to Foster Discovery Learning For the typical undergraduate engineering student the topic of gears is introduced and discussed in several courses. Early exposure may be in a physics course or in a first dynamics course,where gear pairs are presented as an idealized means to change speed ratios and torque ratios.They are used for mechanical advantage or to achieve desired speed, and the focus is usually on kinematics. Since gears have inertia they store kinetic energy and are part of the dynamic equations of motion of mechanisms and machines. For mechanical engineering students, gears are a …

Investigation Of The Surface Adhesion Phenomena And Mechanism Of Gold-Plated Contacts At Superlow Making/Breaking Speed, Wanbin Ren, Cheng Chang, Yu Chen, Shengjun Xue, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

Surface adhesion phenomena of gold-plated copper contact materials are studied in conditions of nonarc load (5/15/25 V and 0.2/0.5/1 A) and superlow speed (25 and 50 nm/s) realized by a piezoactuator during the making and breaking processes. It is shown that softening and melting of local asperities leads to interface adhesion, which results from the joule heat generated by the contact resistance; it is determined that the change of contact force with time obeys the negative exponential distribution and the time constant is associated with the adhesion force directly. Based on the fitting experimental data, the relationship between the adhesion …

Relating The Experimental Ionization Coefficients In Semiconductors To The Nonlocal Ionization Coefficients, Jeng Shiuh Cheong, Majeed M. Hayat, Xinxin Zhou, John P.R. David

Electrical and Computer Engineering Faculty Research and Publications

The experimentally determined impact ionization coefficients, , include intrinsically the presence of a dead-space, where carriers cannot impact ionize as they do not have sufficient energy. These, therefore, cannot be used by nonlocal ionization models, which require the enabled ionization coefficients, which describe the ionization probability after the dead-space. A relatively simple relationship is shown to exist between α'(β') and , which requires only the knowledge of the carrier threshold energies. This allows conventionally limited to the local model framework, to be used to give a very good prediction of the avalanche multiplication and excess noise for a wide range …