Engineering Commons^™

Investigation Of Fault-Tolerant Capabilities In An Advanced Three-Level Active T-Type Converter, Ramin Katebi, Jiangbiao He, Nathan Weise

Electrical and Computer Engineering Faculty Research and Publications

A novel fault-tolerant three-level power converter topology, named advanced three-level active T-Type (A₃L-ATT) converter, is introduced to increase the reliability of multilevel power converters used in safety-critical applications. This new fault-tolerant multilevel power converter is derived from the conventional T-Type converter topology. The topology has significantly improved the fault-tolerant capability under any open circuit or certain short-circuit faults in the semiconductor devices. In addition, under healthy condition, the redundant phase leg can be utilized to share overload current with other main legs, which enhances the overload capability of the converter. The conduction losses in the original outer devices …

High Specific Power Electrical Machines: A System Perspective, Ayman M. El-Refaie, Mohamed Osama

Electrical and Computer Engineering Faculty Research and Publications

There has been a growing need for high specific power electrical machines for a wide range of applications. These include hybrid/electric traction applications, aerospace applications and Oil and Gas applications. A lot of work has been done to accomplish significantly higher specific power electrical machines especially for aerospace applications. Several machine topologies as well as thermal management schemes have been proposed. Even though there has been a few publications that provided an overview of high-speed and high specific power electrical machines [1-3], the goal of this paper is to provide a more comprehensive review of high specific power electrical machines …

Closed-Form Solution For Curling Responses In Rigid Pavements, Jaime Hernandez, Imad L. Al-Qadi

Civil and Environmental Engineering Faculty Research and Publications

Closed-form expressions for calculating stresses and displacements of partially restrained concrete pavement caused by a linear temperature gradient are presented. Translational and rotational linear elastic springs along the slab edges defined the partial restraint. In addition to plate theory behavior, the model assumes linear elastic concrete and an infinitely long slab resting on a Winkler foundation. The solutions of curling stresses and displacements were validated using the finite-element (FE) method and quantified the effect of semirigid connections, slab and foundation material properties, and slab thickness and width on them. Rotational and translational restraints, which can be related to joint condition …

From Micro To Macro-Contaminants: The Impact Of Low-Energy Titanium Dioxide Photocatalysis Followed By Filtration On The Mitigation Of Drinking Water Organics, Brooke K. Mayer, Carlan Johnson, Yu Yang, Nicole Wellenstein, Emily K. Maher, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

This study evaluated strategies targeting macro- and micro-organic contaminant mitigation using low-energy titanium dioxide photocatalysis. Energy inputs of 1, 2, and 5 kWh m⁻³ resulted in incomplete oxidation of macro-organic natural organic matter, signified by greater reductions of UV₂₅₄ and specific ultraviolet UV absorbance (SUVA) in comparison to dissolved organic carbon (DOC). The rate of UV₂₅₄ removal was 3 orders of magnitude greater than the rate of DOC degradation. Incomplete oxidation improved operation of downstream filtration processes. Photocatalysis at 2 kWh m⁻³ increased the bed life of downstream granular activated carbon (GAC) filtration by 340% relative …

Toxicity Of Various Pyrolysis Liquids From Biosolids On Methane Production Yield, Seyedfatemeh Seyedi, Kaushik Venkiteshwaran, Daniel Zitomer

Civil and Environmental Engineering Faculty Research and Publications

Aqueous pyrolysis liquid (APL) is a high-COD byproduct of wastewater biosolids pyrolysis that is comprised of numerous complex organic compounds and ammonia nitrogen (NH₃-N). One potential beneficial use of APL is as a co-digestate to produce more biogas in anaerobic digesters. However, some APL organics and NH₃-N are known to inhibit methane-producing microbes. Autocatalytic pyrolysis which uses previously-produced biochar as a catalyst during biosolids pyrolysis, increases energy-rich py-gas while eliminating bio-oil production and reducing COD concentration in the APL (catalyzed APL). However, the catalyzed APL still has a high organic strength and no suitable treatment strategies …

Kinematic Foot Types In Youth With Pes Planovalgus Secondary To Cerebral Palsy, Juliet Amene, Joseph J. Krzak, Karen M. Kruger, Logan Killen, Haluk Altiok, Peter A. Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background

Kinematic variability of the foot and ankle segments exists during ambulation among individuals with pes planovalgus (PPV) secondary to cerebral palsy (CP). Clinicians have previously recognized such variability through classification schemes to identify subgroups of individuals, but have been unable to identify kinematic foot types.

Research question

The purpose of this work was to identify kinematic foot types among children with PPV secondary to CP using 3-dimensional multi-segment foot and ankle kinematics during gait as inputs for principal component analysis (PCA) and K-means cluster analysis.

Methods

In a single assessment session, multi-segment foot and ankle kinematics using the …

A Detailed Modeling Study Of Radiative Heat Transfer In A Heavy-Duty Diesel Engine, Chandan Paul, Sebastian Ferreyro Fernandez, Daniel C. Haworth, Somesh Roy, Michael F. Modest

Mechanical Engineering Faculty Research and Publications

In recent years, the importance of radiative heat transfer in combustion has been increasingly recognized. Detailed models have become available that accurately represent the complex spectral radiative properties of reacting gas mixtures and soot particles, and new methods have been developed to solve the radiative transfer equation (RTE). At the same time, the trends toward higher operating pressures and higher levels of exhaust-gas recirculation in compression-ignition engines, together with the demand for higher quantitative accuracy from in-cylinder CFD models, has led to renewed interest in radiative transfer in engines. Here an in-depth investigation of radiative heat transfer is performed for …

A Fast, Linear Boltzmann Transport Equation Solver For Computed Tomography Dose Calculation (Acuros Ctd), Adam Wang, Alexander Maslowski, Todd Wareing, Josh Star-Lack, Taly Gilat-Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose

To improve dose reporting of CT scans, patient‐specific organ doses are highly desired. However, estimating the dose distribution in a fast and accurate manner remains challenging, despite advances in Monte Carlo methods. In this work, we present an alternative method that deterministically solves the linear Boltzmann transport equation (LBTE), which governs the behavior of x‐ray photon transport through an object.

Methods

Our deterministic solver for CT dose (Acuros CTD) is based on the same approach used to estimate scatter in projection images of a CT scan (Acuros CTS). A deterministic method is used to compute photon fluence within the …

Permanent Magnet Vernier Machine: A Review, Fan Wu, Ayman M. El-Refaie

Electrical and Computer Engineering Faculty Research and Publications

Permanent magnet vernier machines (PMVMs) gained a lot of interest over the past couple of decades. This is mainly due to their high torque density enabled by the magnetic gearing effect. This study will provide a thorough review of recent advances in PMVMs. This review will cover the principle of operation and nature of magnetic gearing in PMVMs, and a better understanding of novel PMVM topologies using different winding configuration as well as different modulation poles and rotor structures. Detailed discussions on the choice of gear ratio, slot-pole combinations, design optimisation and role of advanced materials in PMVMs will be …

Novel Test Fixture For Characterizing Mems Switch Microcontact Reliability And Performance, Protap Mahanta, Farhana Anwar, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

In microelectromechanical systems (MEMS) switches, the microcontact is crucial in determining reliability and performance. In the past, actual MEMS devices and atomic force microscopes (AFM)/scanning probe microscopes (SPM)/nanoindentation-based test fixtures have been used to collect relevant microcontact data. In this work, we designed a unique microcontact support structure for improved post-mortem analysis. The effects of contact closure timing on various switching conditions (e.g., cold-switching and hot-switching) was investigated with respect to the test signal. Mechanical contact closing time was found to be approximately 1 us for the contact force ranging from 10–900 μN. On the other hand, for the 1 …

Direct-To-Patient Survey For Diagnosis Of Benign Paroxysmal Positional Vertigo, Heidi Richburg, Richard J. Povinelli, David Friedland

Electrical and Computer Engineering Faculty Research and Publications

Given the high incidence of dizziness and its frequent misdiagnosis, we aim to create a clinical support system to classify the presence or absence of benign paroxysmal positional vertigo with high accuracy and specificity. This paper describes a three-phase study currently underway for classification of benign paroxysmal positional vertigo, which includes diagnosis by a specialist in a clinical setting. Patient background information is collected by a survey on an Android tablet and machine learning techniques are applied for classification. Decision trees and wrappers are employed for their ability to provide information about the question set. One goal of the study …

A Hybrid Droplet Vaporization-Chemical Surrogate Approach For Emulating Vaporization, Physical Properties, And Chemical Combustion Behavior Of Multicomponent Fuels, Alanna Y. Cooney, Simcha L. Singer

Mechanical Engineering Faculty Research and Publications

The complex nature of multicomponent aviation fuels presents a daunting task for accurately simulating combustion behavior without incurring impractical computational costs. To reduce computation time, chemical fuel surrogates comprised of only a few species are used to emulate the combustion of complex pre-vaporized fuels. These surrogates are often unable to match the vaporization behavior and physical properties of the real fuel and fail to capture the effect of preferential vaporization on combustion behavior. Therefore, a computationally efficient, hybrid droplet vaporization-chemical surrogate approach has been developed which emulates both the physical and chemical properties of a multicomponent kerosene fuel. The droplet …

Using Online Discussions To Develop The Entrepreneurial Mindset In Environmental Engineering Undergraduates: A Case Study, Lisa B. Bosman, Nathalie Duval-Couetil, Brooke K. Mayer, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Entrepreneurship is an important aspect of the U.S. and global economy. As such, developing an entrepreneurial mindset is crucial for both engineering students and practicing engineers. The purpose of this paper is investigate the role of online discussions, as a pedagogical approach, in the development of the entrepreneurial mindset, and explore a variety of approaches to assess student learning outcomes. Online discussions prompts were created for environmental engineering courses using the Kern Engineering Entrepreneurial Network (KEEN) framework. The framework proposes that an entrepreneurial mindset can be fostered in students by promoting curiosity, encouraging connections, and creating value. This paper describes …

Attitudes Toward Failure In Capstone Design Projects, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

While working in industry during the 1980s and 1990s, project failures were to be avoided at all costs. For engineers in the medical device industry, these failures could be in the form of: 1) an idea for a new product or feature that eventually failed due to technical infeasibility, regulatory hurdles, lack of market interest, or difficulty in manufacturing; 2) a prototype that did not function as required; or 3) an animal or human clinical study that yielded poor results. They typically resulted in significant project delays, wasted time and money, and lost revenues, and often led to lower raises, …

Long-Term Impact On Environmental Attitudes And Knowledge Assessed Over Three Semesters Of An Environmental Engineering Sequence, Benjamin Michael Wallen, Nathaniel Sheehan, Luke Plante, Erick Martinez, Jeffrey A. Starke

Civil and Environmental Engineering Faculty Research and Publications

The pedagogy employed in a three-course environmental engineering sequence is investigated to determine the efficacy of enabling long-term improvement of knowledge and attitudes toward the environment. These three courses incorporate concepts of the five grand challenges released by the National Academy of Engineering and National Academy of Sciences and increase the breadth of knowledge for T-professionals. Previous studies of lengths from a few weeks to semester long courses evaluated the potential causality among various demographics and environmental knowledge and attitudes. The research presented herein contrasts and compares changes in environmental knowledge based upon a 12-question survey and changes in environmental …

Sdn Testbed For Evaluation Of Large Exo-Atmospheric Emp Attacks, Diogo Oliveira, Nasir Ghani, Majeed M. Hayat, Jorge Crichigno, Elias Bou-Harb

Electrical and Computer Engineering Faculty Research and Publications

Large-scale nuclear electromagnetic pulse (EMP) attacks and natural disasters can cause extensive network failures across wide geographic regions. Although operational networks are designed to handle most single or dual faults, recent efforts have also focused on more capable multi-failure disaster recovery schemes. Concurrently, advances in software-defined networking (SDN) technologies have delivered highly-adaptable frameworks for implementing new and improved service provisioning and recovery paradigms in real-world settings. Hence this study leverages these new innovations to develop a robust disaster recovery (counter-EMP) framework for large backbone networks. Detailed findings from an experimental testbed study are also presented.

Microscale Direct Measurement Of Localized Photothermal Heating In Tissue-Mimetic Hydrogels, Benyamin Davaji, James E. Richie, Chung-Hoon Lee

Electrical and Computer Engineering Faculty Research and Publications

Photothermal hyperthermia is proven to be an effective diagnostic tool for cancer therapy. The efficacy of this method directly relies on understanding the localization of the photothermal effect in the targeted region. Realizing the safe and effective concentration of nano-particles and the irradiation intensity and time requires spatiotemporal temperature monitoring during and after laser irradiation. Due to uniformities of the nanoparticle distribution and the complexities of the microenvironment, a direct temperature measurement in micro-scale is crucial for achieving precise thermal dose control. In this study, a 50 nm thin film nickel resistive temperature sensor was fabricated on a 300 nm …

Predicting Cascading Failures In Power Grids Using Machine Learning Algorithms, Rezoan Ahmed Shuvro, Pankaz Das, Majeed M. Hayat, Mitun Talukder

Electrical and Computer Engineering Faculty Research and Publications

Although there has been notable progress in modeling cascading failures in power grids, few works included using machine learning algorithms. In this paper, cascading failures that lead to massive blackouts in power grids are predicted and classified into no, small, and large cascades using machine learning algorithms. Cascading-failure data is generated using a cascading failure simulator framework developed earlier. The data set includes the power grid operating parameters such as loading level, level of load shedding, the capacity of the failed lines, and the topological parameters such as edge betweenness centrality and the average shortest distance for numerous combinations of …

Estimating The Spectrum In Computed Tomography Via Kullback–Leibler Divergence Constrained Optimization, Wooseok Ha, Emil Y. Sidky, Rina Foygel Barber, Taly Gilat Schmidt, Xiaochuan Pan

Biomedical Engineering Faculty Research and Publications

Purpose

We study the problem of spectrum estimation from transmission data of a known phantom. The goal is to reconstruct an x‐ray spectrum that can accurately model the x‐ray transmission curves and reflects a realistic shape of the typical energy spectra of the CT system.

Methods

Spectrum estimation is posed as an optimization problem with x‐ray spectrum as unknown variables, and a Kullback–Leibler (KL)‐divergence constraint is employed to incorporate prior knowledge of the spectrum and enhance numerical stability of the estimation process. The formulated constrained optimization problem is convex and can be solved efficiently by use of the exponentiated‐gradient (EG) …

Investigation Of Void Formation In Friction Stir Welding Of 7n01 Aluminum Alloy, Xingxin Zhao, Jianmin Han, Joseph P. Domblesky, Zhiyong Yang, Zhiqiang Li, Xiaolong Liu

Mechanical Engineering Faculty Research and Publications

Friction Stir Welding (FSW) is a solid state joining process that is widely used to produce high integrity aluminum weldments for a variety of industries. While extensive work has been conducted to understand flow behavior, much less research has been performed to identify how void defects form and how to predict them. In the present study, the relationship between rotation speed, plasticized region, and defect formation was investigated. To analyze how tunneling and cavity type void defects form during FSW, a 3-D Computational fluid dynamics(CFD) model based on the Fluent software code was used to simulate butt welding. The CFD …

Effect Of Diffusion Distance On Evolution Of Kirkendall Pores In Titanium-Coated Nickel Wires, Aaron R. Yosta, Dinc Erdeniz, Ashley E. Paz Y Puente, David C. Dunanda

Mechanical Engineering Faculty Research and Publications

Microtubes of near-equiatomic nickel-titanium (NiTi) alloys can be created via the Kirkendall effect during NiTi interdiffusion, when nickel wires are surface-coated with titanium via pack cementation and subsequently homogenized. This study explores the effect of diffusion distance upon Kirkendall microtube formation in NiTi by considering a range of Ni wire diameters. For Ni wire diameters of 25, 50 and 100 μm, titanized at 925 °C for 0.5, 2, and 8 h to achieve average NiTi composition, partial interdiffusion occurs concurrently with Ti surface deposition, resulting in concentric shells of NiTi₂, NiTi and Ni₃Ti around a Ni …

Structure And Growth Of Core–Shell Nanoprecipitates In Al–Er–Sc–Zr–V–Si High-Temperature Alloys, Wahaz Nasim, Saegh Yazdi, Ruben Santamarta, Jahanzaib Malik, Dinc Erdeniz, Bilal Mansoor, David N. Seidman, David C. Dunand, Ibrahim Karaman

Mechanical Engineering Faculty Research and Publications

Lightweight Sc-containing aluminum alloys exhibit superior mechanical performance at high temperatures due to core–shell, L1₂-ordered trialuminide nanoprecipitates. In this study, the structure of these nanoprecipitates was studied, using different transmission electron microscopy (TEM) techniques, for an Al–Er– Sc–Zr–V–Si alloy that was subjected to a two-stage overaging heat treatment. Energy-dispersive X-ray spectroscopy of the spherical Al₃(Sc, Zr, Er ,V) nanoprecipitates revealed a core–shell structure with an Sc- and Er-enriched core and a Zr-enriched shell, without a clear V outer shell. This structure is stable up to 72% of the absolute melting temperature of Al for extended periods …

An Efficient Monte Carlo-Based Solver For Thermal Radiation In Participating Media, Joseph Farmer, Somesh Roy

Mechanical Engineering Faculty Research and Publications

Monte Carlo-based solvers, while well-suited for accurate calculation of complex thermal radiation transport problems in participating media, are often deemed computationally unattractive for use in the solution of real-world problems. The main disadvantage of Monte Carlo (MC) solvers is their slow convergence rate and relatively high computational cost. This work presents a novel approach based on a low-discrepancy sequence (LDS) and is proposed for reducing the error bound of a Monte Carlo-based radiation solver. Sobols sequence – an LDS generated with a bit-by-bit exclusive-or operator – is used to develop a quasi-Monte Carlo (QMC) solver for thermal radiation in this …

Ct Automated Exposure Control Using A Generalized Detectability Index, P. Khobragade, Franco Rupcich, Jiahua Fan, Dominic J. Crotty, Naveen M. Kulkarni, Stacy D. O'Connor, W. Dennis Foley, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose

Identifying an appropriate tube current setting can be challenging when using iterative reconstruction due to the varying relationship between spatial resolution, contrast, noise, and dose across different algorithms. This study developed and investigated the application of a generalized detectability index (d'_gen) to determine the noise parameter to input to existing automated exposure control (AEC) systems to provide consistent image quality (IQ) across different reconstruction approaches.

Methods

This study proposes a task‐based automated exposure control (AEC) method using a generalized detectability index (d'_gen). The proposed method leverages existing AEC methods that are based on a prescribed …

Spatial And Temporal Influences On Discrimination Of Vibrotactile Stimuli On The Arm, Valay Shah, Maura Casadio, Robert A. Scheidt, Leigh A. Mrotek

Biomedical Engineering Faculty Research and Publications

Body–machine interfaces (BMIs) provide a non-invasive way to control devices. Vibrotactile stimulation has been used by BMIs to provide performance feedback to the user, thereby reducing visual demands. To advance the goal of developing a compact, multivariate vibrotactile display for BMIs, we performed two psychophysical experiments to determine the acuity of vibrotactile perception across the arm. The first experiment assessed vibration intensity discrimination of sequentially presented stimuli within four dermatomes of the arm (C5, C7, C8, and T1) and on the ulnar head. The second experiment compared vibration intensity discrimination when pairs of vibrotactile stimuli were presented simultaneously vs. sequentially …

Computational Characterization Of The Cellular Origins Of Electroencephalography, Shane Hesprich, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Despite the widespread use of Electroecephalography (EEG) as an imaging modality, neural generators of current dipoles measured by EEG at the scalp are not fully understood. Here, we use two morphologically accurate multicompartments neuron models (layer IV pyramidal cell and layer V spiny stellate cell) to characterize how spiking neurons generate current dipoles in response to synaptic input. The simulations indicate that the dipole generated by synaptic inputs required to drive a pyramidal cell to threshold is smaller than the dipole associated the action potential itself. These results suggest a greater role of spiking neural activity toward EEG signals measured …

Age Grading An. Gambiae And An. Arabiensis Using Near Infrared Spectra And Artificial Neural Networks, Masabho Peter Milali, Maggy T. Sikulu-Lord, Samson S. Kiware, Floyd E. Dowell, George F. Corliss, Richard J. Povinelli

Electrical and Computer Engineering Faculty Research and Publications

Background

Near infrared spectroscopy (NIRS) is currently complementing techniques to age-grade mosquitoes. NIRS classifies lab-reared and semi-field raised mosquitoes into < or ≥ 7 days old with an average accuracy of 80%, achieved by training a regression model using partial least squares (PLS) and interpreted as a binary classifier.

Methods and findings

We explore whether using an artificial neural network (ANN) analysis instead of PLS regression improves the current accuracy of NIRS models for age-grading malaria transmitting mosquitoes. We also explore if directly training a binary classifier instead of training a regression model and interpreting it as a binary classifier improves the accuracy. A total of 786 and 870 NIR spectra collected from laboratory reared An. gambiae and An. arabiensis, respectively, were used and pre-processed according …

Meta-Analysis Of Non-Reactive Phosphorus In Water, Wastewater, And Sludge, And Strategies To Convert It For Enhanced Phosphorus Removal And Recovery, Kaushik Venkiteshwaran, Patrick J. Mcnamara, Brooke K. Mayer

Civil and Environmental Engineering Faculty Research and Publications

Current and future trends indicate that mining of natural phosphorus (P) reserves is occurring faster than natural geologic replenishment. This mobilization has not only led to P supply concerns, but has also polluted many of the world's freshwater bodies and oceans. Recovery and reuse of this nuisance P offers a long-term solution simultaneously addressing mineral P accessibility and P-based pollution. Available physical, chemical, and biological P removal/recovery processes can achieve low total P (TP) concentrations (≤100 μg/L) and some processes can also recover P for direct reuse as fertilizers (e.g., struvite). However, as shown by our meta-analysis of over 20,000 …

Stochastic Water Balance Dynamics Of Passive And Controlled Stormwater Basins, Anthony J. Parolari, Steven Pelrine, Mark S. Bartlett

Civil and Environmental Engineering Faculty Research and Publications

Urbanization and changing rainfall intensities affect the performance of urban stormwater infrastructure, creating the necessity to design resilient stormwater systems. One proposed method to increase the resilience of stormwater infrastructure is the active control of system flows. To improve the understanding of actively-controlled urban water infrastructure function under variable hydro-climate, we develop a stochastic water balance model for stormwater retention and detention basins with both passive and actively-controlled outflow structures. Under active outflow control, the outflow valve is closed until the water level in the basin reaches a specified maximum at which point the valve opens and the basin empties. …

Epoxy Interlocking: A Novel Approach To Enhance Frp-To-Concrete Bond Behavior, Cheng Jiang, Baolin Wan, Yu-Fei Wu, John Omboko

Civil and Environmental Engineering Faculty Research and Publications

This paper presents a novel approach which can enhance the interfacial bond behavior between fiber reinforced polymer (FRP) composite material and concrete. Epoxy ribs are formed by grooving on the concrete surface before epoxy is applied. The dowel action from the epoxy ribs leads to an “epoxy interlocking” effect. The mechanism of the proposed epoxy interlocking approach was analyzed in this paper from both adhesion and interlocking aspects. Furthermore, the partial interaction of the epoxy interlocking was quantified and calibrated by experimental results. The epoxy interlocking in the tested specimens led to an 88.8% increase in bond strength on average. …