Engineering Commons^™

Design Of Ferroelectric Mems Energy Harvesting Devices, Noah T. Blach, Robert A. Lake, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

Waste heat is a widely available but little used source of power. Converting a thermal gradient into electricity is conventionally done using the Seebeck effect, but devices that use this effect are naturally inefficient. An alternate approach uses microelectromechanical systems (MEMS) to generate movement and time-varying temperature from a constant temperature gradient. Ferroelectric materials can harvest electricity from moving structures and temperature variations. This concept was realized using traditional silicon microprocessing techniques. A silicon on insulator (SOI) wafer was backside Deep Reactive Ion Etched (DRIE) to form a one mm² by 7 micron thick silicon/silicon dioxide membrane. Lead zirconate …

Engineered Surfaces To Control Secondary Electron Emission For Multipactor Suppression, James M. Sattler, Ronald A. Coutu Jr., Robert A. Lake, Tod V. Laurvick

Electrical and Computer Engineering Faculty Research and Publications

A significant problem for space-based systems is multipactor - an avalanche of electrons caused by repeated secondary electron emission (SEE). The consequences of multipactor range from altering the operation of radio frequency (RF) devices to permanent device damage. Existing efforts to suppress multipactor rely heavily on limiting power levels below a multipactor threshold [1]. This research applies surface micromachining techniques to create porous surfaces to control the secondary electron yield (SEY) of a material for multipactor suppression. Surface characteristics of interest include pore aspect ratio and density. A discussion is provided on the advantage of using electroplating (vice etching) to …

Standardized Testing Of Non-Standard Photovoltaic Pavement Surfaces, John H. Nussbaum, Robert A. Lake, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

Emerging photovoltaic products have expanded the applications for the technologies into markets previously unconsidered for what was thought to be a delicate electronic product. One company leading this effort, Solar Roadways, Incorporated, is producing pavement replacing photovoltaic systems and proposing their use in everything from sidewalks to runways. Current pavement testing methods cannot be applied to these non-homogenous structures to identify if they can support the required loads. However, the standards called out specifically for pavements may be able to be translated to these products and their non-homogenous structures and non-standard materials to identify if they are able to perform …

Design And Analysis Of Novel Ge-Gete Pn Junction For Photovoltaics, Andrew M. Jones, Ronald A. Coutu Jr., Robert A. Lake

Electrical and Computer Engineering Faculty Research and Publications

The continuing rise in demand for energy places a similarly increasing demand to improve power production methods and efficiency. In regards to solar power generation, one major limiting factor with existing photovoltaic (PV) systems is the management of heat produced and photon interactions with the PV device. Typical devices operate within the 300-1000 nm range of the solar spectrum, greatly limiting the range of photons used for power generation. Furthermore, since infrared light (

Government Motivation-Embedded Return Guarantee For Urban Infrastructure Projects Based On Real Options, Qingpeng Man, Chengshuang Sun, Yuesheng Fei, Martin Skitmore, Yong Bai, Weizhuo Lu

Civil and Environmental Engineering Faculty Research and Publications

Governments usually guarantee the amount of investment income to private sector partners to encourage their participation in Public-Private Partnership urban infrastructure development projects, with the ‘float return on investment guarantee’ being the main method in use by the Chinese government today. The current problems with the float return on investment guarantee are analysed and a guarantee approach with embedded motivational behaviour is presented as an alternative. A pricing method option is then introduced as the motivation-embedded return guarantee has similar characteristics to real options. From this, a valuation model is developed that provides the basis of a new systematic method …

Toward Translating Near-Infrared Spectroscopy Oxygen Saturation Data For The Non-Invasive Prediction Of Spatial And Temporal Hemodynamics During Exercise, Laura M. Ellwein, Margaret M. Samyn, Michael E. Danduran, Sheila M. Schindler-Ivens, Stacy Liebham, John F. Ladisa Jr.

Exercise Science Faculty Research and Publications

Image-based computational fluid dynamics (CFD) studies conducted at rest have shown that atherosclerotic plaque in the thoracic aorta (TA) correlates with adverse wall shear stress (WSS), but there is a paucity of such data under elevated flow conditions. We developed a pedaling exercise protocol to obtain phase contrast magnetic resonance imaging (PC-MRI) blood flow measurements in the TA and brachiocephalic arteries during three-tiered supine pedaling at 130, 150, and 170 % of resting heart rate (HR), and relate these measurements to non-invasive tissue oxygen saturation (StO₂) acquired by near-infrared spectroscopy (NIRS) while conducting the same protocol. Local quantification …

Analytical Modeling Of A Novel Microdisk Resonator For Liquid-Phase Sensing: An All-Shear Interaction Device (Asid), Mohamad Sadegh Sotoudegan

Dissertations (1934 -)

Extensive research on micro/nanomechanical resonators has been performed recently due to their potential to serve as ultra-sensitive devices in chemical/biosensing. These applications often necessitate liquid-phase sensing, introducing significant fluid-induced inertia and energy dissipation that reduces the resonator’s performance. To minimize the detrimental fluid effects on such devices, a novel microdisk resonator supported by two tangentially-oriented, axially-driven “legs” is investigated analytically and effects of the system parameters on the resonator/sensor performance are explored. Since the device surface vibrates primarily parallel to the fluid-structure interface, it is referred to here as an “all-shear interaction device,” or ASID. Analytical modeling of the ASID …

Robust And Resilient Control Design And Performance Analysis For Uncertain Systems With Finite Energy Disturbances, Fan Feng

Dissertations (1934 -)

This dissertation addresses the problem of robust and resilient control design with additional performance analysis for uncertain systems with finite energy disturbances. The control design is robust and resilient in the sense of maintaining certain performance criteria in the presence of perturbations in both system parameters and feedback gains. The performance analysis evaluates resilience properties of state feedback and dynamic (state estimate) feedback controllers. A resilient and robust state feedback controller is designed using linear matrix inequality (LMI) techniques for the characterization of solutions to the analysis and design problems posed in this work. Uncertainties are allowed in the linear …

Flight Control And Hardware Design Of Multi-Rotor Systems, Nathan M. Zimmerman

Master's Theses (2009 -)

This thesis overviews crucial concepts involved in achieving quadcopter flight such as orientation estimation and control system implementation. This thesis also presents researchers with comprehensive hardware and software specifications for a quadcopter system. The primary application for this system would be for research with regards to the implementation of advance control techniques as well as data acquisition. Key constructs of this system include hardware software specifications for a flight controller, the radio system, and the sensorless brushless motor controllers. Firstly, the thesis starts by developing a reference frame and a mathematical model for the quadcotper system. Next, flight orientation estimation …

Mims: Mobile Interruption Management System, Mohammad Kayes Kaykobad

Master's Theses (2009 -)

Mobile devices are increasing in an astronomical rate throughout the world. While it is bringing a lot of comfort to the users it is not coming without any hazards. Now a user is susceptible to mobile call interruptions wherever he is, whether he is in the middle of a very important discussion or in a very important task like performing a complicated emergency operation in a hospital. As a result researchers have been studying to find ways to minimize cost of mobile interruptions. In this thesis we have proposed a mobile interruption management system in which callers have been grouped …

Functional Comparison Of Conventional Afos With The Dynamic Response Afo, Mitchell Ruble

Master's Theses (2009 -)

Ankle foot orthoses (AFOs) are commonly prescribed to provide stability and foot clearance for patients with weakened or injured musculature. The Dynamic Response AFO (DRAFO) was designed to improve proprioception at heel strike. The design includes a rigid outer shell with a cut out heel and a soft inner lining; it is typically aligned in plantarflexion and may incorporate external heel wedges. The objective of this study was to investigate the effects of the DRAFO design features and contrast its biomechanical function with that of conventional locked and articulating AFOs. The research hypotheses were: 1) DRAFO-assisted gait parameters (e.g. ankle …

Analysis And Synthesis Of A Planar Reconfigurable Mechanism With A Variable Joint, Peter William Malak

Master's Theses (2009 -)

Currently, there is a demand for mechanisms with variable topology that can perform multiple tasks with the least amount of actuators. These devices have the ability to provide numerous motion profiles within one device. In the following thesis, a specific planar reconfigurable mechanism with a kinematic reconfigurable joint was mathematically modeled. This mechanism functions as a RRRP mechanism in one configuration and as a RRRR in the other and is known as a RRRR-RRRP Mechanism. The kinematics and kinetics of the RRRR-RRRP Mechanism were analyzed with a Lagrangian approach. The models are simulated and verified using a trajectory planner and …

An Interactive Likelihood For The Multi-Bernoulli Filter, Anthony B. Hoak

Master's Theses (2009 -)

In this thesis, a simple yet effective technique is presented for increasing the accuracy of multi-target tracking algorithms with a focus on sequential Monte-Carlo implementations of random finite set-based approaches. This technique, referred to throughout this work as an interactive likelihood, exploits the spatial information that exists in any given measurement, reducing the need for data association and allowing for more target interaction thereby increasing overall tracking accuracy. The interactive likelihood is constructed entirely within the random finite set framework and is integrated with a multi-Bernoulli filter. In addition, a state-of-the-art deep neural network for pedestrian detection is combined in …

On The Importance Of Displacement History In Soft-Body Contact Models, Jonathan A. Fleischmann, Radu Serban, Dan Negrut, Paramsothy Jayakumar

Mechanical Engineering Faculty Research and Publications

Two approaches are commonly used for handling frictional contact within the framework of the discrete element method (DEM). One relies on the complementarity method (CM) to enforce a nonpenetration condition and the Coulomb dry-friction model at the interface between two bodies in mutual contact. The second approach, called the penalty method (PM), invokes an elasticity argument to produce a frictional contact force that factors in the local deformation and relative motion of the bodies in contact. We give a brief presentation of a DEM-PM contact model that includes multi-time-step tangential contact displacement history. We show that its implementation in an …

Bioaugmentation And Correlating Anaerobic Digester Microbial Community To Process Function, Kaushik Venkiteshwaran

Dissertations (1934 -)

This dissertation describes two research projects on anaerobic digestion (AD) that investigated the relationship between microbial community structure and digester function. Both archaeal and bacterial communities were characterized using high-throughput (Illumina) sequencing technology with universal 16S rRNA gene primers. In the first project, bioaugmentation using a methanogenic, aerotolerant propionate enrichment culture was investigated as a possible method to increase digester methane production. Nine anaerobic digesters, seeded with different biomass, were operated identically and their quasi steady state function was compared. Before bioaugmentation, different seed biomass resulted in different quasi steady state function, with digesters clustering into high, medium or low …

Predicting Multiple Target Tracking Performance For Applications On Video Sequences, Juan Esteban Tapiero Bernal

Dissertations (1934 -)

This dissertation presents a framework to predict the performance of multiple target tracking (MTT) techniques. The framework is based on the mathematical descriptors of point processes, the probability generating functional (p.g.fl). It is shown that conceptually the p.g.fls of MTT techniques can be interpreted as a transform that can be marginalized to an expression that encodes all the information regarding the likelihood model as well as the underlying assumptions present in a given tracking technique. In order to use this approach for tracker performance prediction in video sequences, a framework that combines video quality assessment concepts and the marginalized transform …

Design Optimization Of Permanent Magnet Machines Over A Target Operating Cycle Using Computationally Efficient Techniques, Alireza Fatemi

Dissertations (1934 -)

The common practices of large-scale finite element (FE) model-based design optimization of permanent magnet synchronous machines (PMSMs) oftentimes aim at improving the machine performance at the rated operating conditions, thus overlooking the performance treatment over the entire range of operation in the constant torque and extended speed regions. This is mainly due to the computational complexities associated with several aspects of such large-scale design optimization problems, including the FE-based modeling techniques, large number of load operating points for load-cycle evaluation of the design candidates, and large number of function evaluations required for identification of the globally optimal design solutions. In …

Cascading Failures In Interdependent Infrastructures: An Interdependent Markov-Chain Approach, Mahshid Rahnamay-Naeini, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

Many critical infrastructures are interdependent networks in which the behavior of one network impacts those of the others. Despite the fact that interdependencies are essential for the operation of critical infrastructures, such interdependencies can negatively affect the reliability and fuel the cascade of failures within and across the networks. In this paper, a novel interdependent Markov-chain framework is proposed that enables capturing interdependencies between two critical infrastructures with the ultimate goal of predicting their resilience to cascading failures and characterizing the effects of interdependencies on system reliability. The framework is sufficiently general to model cascading failures in any interdependent networks; …

Probabilistic Anomaly Detection In Natural Gas Time Series Data, Hermine Nathalie Akouemo Kengmo Kenfack, Richard J. Povinelli

Electrical and Computer Engineering Faculty Research and Publications

This paper introduces a probabilistic approach to anomaly detection, specifically in natural gas time series data. In the natural gas field, there are various types of anomalies, each of which is induced by a range of causes and sources. The causes of a set of anomalies are examined and categorized, and a Bayesian maximum likelihood classifier learns the temporal structures of known anomalies. Given previously unseen time series data, the system detects anomalies using a linear regression model with weather inputs, after which the anomalies are tested for false positives and classified using a Bayesian classifier. The method can also …

Attenuation Of The Ganglion Cell Layer In A Premature Infant Revealed With Handheld Spectral Domain Optical Coherence Tomography, Mara R. Goldberg, Fouad R. Zakka, Joseph Carroll, Deborah M. Costakos

Biomedical Engineering Faculty Research and Publications

Purpose: To report on subclinical retinal abnormalities shown through handheld spectral domain optical coherence tomography on a premature infant.

Methods: Case report.

Results: The initial and follow-up exams on a premature infant revealed severely attenuated ganglion cell and nerve fiber layers. There was cystoid macular edema in both eyes at the initial visits, which resolved by the 1-year follow-up.

Discussion: Optical coherence tomography can reveal significant retinal abnormalities in premature infants which are not detectable through funduscopic exam. Documenting such findings may be useful for the comprehensive management of vision problems in children with a history of premature birth.

Co-Ops And Capstone Design: Are They Interchangeable?, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

Many engineering schools in the United States provide opportunities for their undergraduate students to gain practical, real-world experience in their chosen disciplines. Cooperative education is a structured method of combining classroom-based education with practical work experience. A cooperative education experience, commonly known as a co-op, provides academic credit (and pay) for such an experience. Discusses the benefits of these working experiences, focusing on capstone design courses.

Optimal Design Of Ipm Motors With Different Cooling Systems And Winding Configurations, Alireza Fatemi, Dan M. Ionel, Nabeel Demerdash, Thomas W. Nehl

Electrical and Computer Engineering Faculty Research and Publications

Performance improvement of permanent magnet (PM) motors through optimization techniques has been widely investigated in the literature. Oftentimes the practice of design optimization leads to derivation/interpretation of optimal scaling rules of PM motors for a particular loading condition. This paper demonstrates how these derivations vary with respect to the machine ampere loading and ferrous core saturation level. A parallel sensitivity analysis using a second-order response surface methodology followed by a large-scale design optimization based on evolutionary algorithms are pursued in order to establish the variation of the relationships between the main design parameters and the performance characteristics with respect to …

Fast Multi-Objective Cmode-Type Optimization Of Pm Machines Using Multicore Desktop Computers, Alireza Fatemi, Dan M. Ionel, Nabeel Demerdash, Thomas W. Nehl

Electrical and Computer Engineering Faculty Research and Publications

Large-scale design optimization of electric machines is oftentimes practiced to achieve a set of objectives, such as the minimization of cost and power loss, under a set of constraints, such as maximum permissible torque ripple. Accordingly, the design optimization of electric machines can be regarded as a constrained optimization problem (COP). Evolutionary algorithms (EAs) used in the design optimization of electric machines including differential evolution (DE), which has received considerable attention during recent years, are unconstrained optimization methods that need additional mechanisms to handle COPs. In this paper, a new optimization algorithm that features combined multi-objective optimization with differential evolution …

Benefits Of Considering More Than Temperature Acceleration For Gan Hemt Life Testing, Ronald A. Coutu Jr., Robert A. Lake, Bradley D. Christiansen, Eric R. Heller, Christopher A. Bozada, Brian S. Poling, Glen D. Via, James P. Theimer, Stephen E. Tetlak, Ramakrishna Vetury, Jeffrey B. Shealy

Electrical and Computer Engineering Faculty Research and Publications

The purpose of this work was to investigate the validity of Arrhenius accelerated-life testing when applied to gallium nitride (GaN) high electron mobility transistors (HEMT) lifetime assessments, where the standard assumption is that only critical stressor is temperature, which is derived from operating power, device channel-case, thermal resistance, and baseplate temperature. We found that power or temperature alone could not explain difference in observed degradation, and that accelerated life tests employed by industry can benefit by considering the impact of accelerating factors besides temperature. Specifically, we found that the voltage used to reach a desired power dissipation is important, and …

Forest Soil Carbon And Nitrogen Cycles Under Biomass Harvest: Stability, Transient Response, And Feedback, Anthony J. Parolari, Amilcare Porporato

Civil and Environmental Engineering Faculty Research and Publications

Biomass harvest generates an imbalance in forest carbon (C) and nitrogen (N) cycles and the nonlinear biogeochemical responses may have long-term consequences for soil fertility and sustainable management. We analyze these dynamics and characterize the impact of biomass harvest and N fertilization on soil biogeochemistry and ecosystem yield with an ecosystem model of intermediate complexity that couples plant and soil C and N cycles. Two harvest schemes are modeled: continuous harvest at low intensity and periodic clear-cut harvest. Continuously-harvested systems sustain N harvest at steady-state under net mineralization conditions, which depends on the C:N ratio and respiration rate of decomposers. …

Tunable Split-Ring Resonators Using Germanium Telluride, C. H. Kodama, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

We demonstrate terahertz (THz) split-ring resonator (SRR) designs with incorporated germanium telluride (GeTe) thin films. GeTe is a chalcogenide that undergoes a nonvolatile phase change from the amorphous to crystalline state at approximately 200 degrees C, depending on the film thickness and stoichiometry. The phase change also causes a drop in the material’s resistivity by six orders of magnitude. In this study, two GeTe-incorporated SRR designs were investigated. The first was an SRR made entirely out of GeTe and the second was a gold SRR structure with a GeTe film incorporated into the gap region of the split ring. These …

Effect Of Original Layer Thicknesses On The Interface Bonding And Mechanical Properties Of Ti-Al Laminate Composites, Minyu Fan, Joseph P. Domblesky, Kai Jin, Liang Qin, Shengqiang Cui, Xunzhong Guo, Naksoo Kim, Jie Tao

Mechanical Engineering Faculty Research and Publications

It is of great significance in high-temperature aeroengine applications for large-surface-area TiAl laminate composites to be fabricated into Ti-Al₃Ti parts by plastic forming and subsequent vacuum hot pressing. Then the original layer thicknesses have an important influence on the interface bonding and mechanical properties of TiAl laminate composites, but only few reports about it have been published so far. In the present study, vacuum hot pressing was employed to fabricate TiAl laminate composites using Ti and Al foils of different thickness. The resulting interface bond and mechanical properties of TiAl laminate composites were then studied to determine the …

Removal Of Trace Metal Contaminants From Potable Water By Electrocoagulation, Joe Heffron, Matt Marhefke, Brooke K. Mayer

Civil and Environmental Engineering Faculty Research and Publications

This study investigated the effects of four operational and environmental variables on the removal of trace metal contaminants from drinking water by electrocoagulation (EC). Removal efficiencies for five metals (arsenic, cadmium, chromium, lead and nickel) were compared under varying combinations of electrode material, post-treatment, water composition and pH. Iron electrodes out-performed aluminum electrodes in removing chromium and arsenic. At pH 6.5, aluminum electrodes were slightly more effective at removing nickel and cadmium, while at pH 8.5, iron electrodes were more effective for these metals. Regardless of electrode, cadmium and nickel removal efficiencies were higher at pH 8.5 than at pH …

Beyond The Scs-Cn Method: A Theoretical Framework For Spatially Lumped Rainfall-Runoff Response, Mark Bartlett, Anthony J. Parolari, Jeffrey Mcdonnell, Amilcare Porporato

Civil and Environmental Engineering Faculty Research and Publications

Since its introduction in 1954, the Soil Conservation Service curve number (SCS-CN) method has become the standard tool, in practice, for estimating an event-based rainfall-runoff response. However, because of its empirical origins, the SCS-CN method is restricted to certain geographic regions and land use types. Moreover, it does not describe the spatial variability of runoff. To move beyond these limitations, we present a new theoretical framework for spatially lumped, event-based rainfall-runoff modeling. In this framework, we describe the spatially lumped runoff model as a point description of runoff that is upscaled to a watershed area based on probability distributions that …

Thermodynamic Properties Of Se-Te(L) Described By An Extension Of The Two Domain Model, Robert F. Brebrick

Mechanical Engineering Faculty Research and Publications

The two domain model of Se-Te liquid is developed further than heretofore. Explicit equations are obtained for the excess Gibbs energy of mixing, the chemical potentials, the enthalpy of mixing, the relative constant pressure heat capacity, and the partial and total pressures. A generally satisfactory fit is obtained for the experimental activity of Te and enthalpy of mixing at 733 K, the relative heat capacity as a function of temperature, and for the total pressure for 99, 60, and 27 at.% Se between about 780 and 1130 K. This is done while leaving unchanged the site fraction of H or …