Engineering Commons^™

Srrs Embedded With Mems Cantilevers To Enable Electrostatic Tuning Of The Resonant Frequency, E. A. Moore, Derrick Langley, Matthew E. Jussaume, L. A. Rederis, C. A. Lundell, Ronald A. Coutu Jr., Peter J. Collins, Lavern A. Starman

Electrical and Computer Engineering Faculty Research and Publications

A microelectromechanical systems (MEMS) cantilever array was monolithically fabricated in the gap region of a split ring resonator (SRR) to enable electrostatic tuning of the resonant frequency. The design consisted of two concentric SRRs each with a set of cantilevers extending across the split region. The cantilever array consisted of five beams that varied in length from 300 to 400 μm, with each beam adding about 2 pF to the capacitance as it actuated. The entire structure was fabricated monolithically to reduce its size and minimize losses from externally wire bonded components. The beams actuate one at a time, longest …

Geometrical Considerations For The Design Of Liquid-Phase Biochemical Sensors Using A Cantilever's Fundamental In-Plane Mode, L. A. Beardslee, Fabien Josse, Stephen M. Heinrich, I. Dufour, O. Brand

Electrical and Computer Engineering Faculty Research and Publications

The influence of the beam geometry on the quality factor and resonance frequency of resonant silicon cantilever beams vibrating in their fundamental in-plane flexural mode in water has been investigated. Compared to cantilevers vibrating in their first out-of-plane flexural mode, utilizing the in-plane mode results in reduced damping and reduced mass loading by the surrounding fluid. Quality factors as high as 86 have been measured in water for cantilevers with a 20 μm thick silicon layer. Based on the experimental data, design guidelines are established for beam dimensions that ensure maximal Q-factors and minimal mass loading by the surrounding …

Low-Loss Meta-Atom For Improved Resonance Response, Derrick Langley, Ronald A. Coutu Jr., Peter J. Collins

Electrical and Computer Engineering Faculty Research and Publications

Measurements of a meta-atom integrated with a low noise amplifier into the split-ring resonator are presented. A comparison is made between baseline meta-atoms and one integrated with a GaAs low noise amplifier. S-parameter measurements in a RF strip-line show the resonant frequency location. The resonance null is more prominent for the integrated meta-atom. Biasing the low noise amplifier from 0 to 7 VDC showed that the resonant null improved with biasing voltage. As the biasing voltage increases, the transmission null reduced from -11.82 to -23.21 dB for biases from 0 to 7 VDC at resonant frequency.

(Mu-Ctl-01-12) Towards Model Driven Game Engineering In Simsys: Requirements For The Agile Software Development Process Game, C. Shaun Longstreet, Kendra M. L. Cooper

Center for Teaching and Learning Technical Reports

Software Engineering (SE) and Systems Engineering (Sys) are knowledge intensive, specialized, rapidly changing disciplines; their educational infrastructure faces significant challenges including the need to rapidly, widely, and cost effectively introduce new or revised course material; encourage the broad participation of students; address changing student motivations and attitudes; support undergraduate, graduate and lifelong learning; and incorporate the skills needed by industry. Games have a reputation for being fun and engaging; more importantly immersive, requiring deep thinking and complex problem solving. We believe educational games are essential in the next generation of e-learning tools. An extensible, freely available, engaging, problem-based game platform …

The Latest Lessons Learned From Retrieval Analyses Of Ultra-High Molecular Weight Polyethylene, Metal-On-Metal, And Alternative Bearing Total Disc Replacements, Steven M. Kurtz, Jeffrey M. Toth, Ryan Siskey, Lauren Ciccarelli, Daniel Macdonald, Jorge Isaza, Todd Lanman, Ilona Punt, Marla Marla Steinbeck, Jan Goffin, André Van Ooij

Biomedical Engineering Faculty Research and Publications

Knowledge regarding the in vivo performance and periprosthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following 4 main questions: (1) What are the latest lessons learned from using polyethylene in large joints and how are they relevant to current TDRs? (2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal cobalt-chrome bearings in large joints and how are they relevant to current TDRs? (3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for …

Relationship Between The Foveal Avascular Zone And Foveal Pit Morphology, Adam M. Dubis, Benjamin R. Hansen, Robert F. Cooper, Joseph Beringer, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Purpose. To assess the relationship between foveal pit morphology and size of the foveal avascular zone (FAZ).

Methods. Forty-two subjects were recruited. Volumetric images of the macula were obtained using spectral domain optical coherence tomography. Images of the FAZ were obtained using either a modified fundus camera or an adaptive optics scanning light ophthalmoscope. Foveal pit metrics (depth, diameter, slope, volume, and area) were automatically extracted from retinal thickness data, whereas the FAZ was manually segmented by two observers to extract estimates of FAZ diameter and area.

Results. Consistent with previous reports, the authors observed significant variation in foveal pit …

Adding Ros Scavengers To Cold K+ Cardioplegia Reduces Superoxide Emission During 2 H Global Cold Cardiac Ischemia, Mohammed Aldakkak, David F. Stowe, James S. Heisner, Matthias L. Riess, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

We reported that the combination of reactive oxygen species (ROS) quenchers Mn(III) tetrakis (4-benzoic acid) porphyrin (MnTBAP), catalase, and glutathione (MCG) given before 2 hours cold ischemia better protected cardiac mitochondria against cold ischemia and warm reperfusion (IR)-induced damage than MnTBAP alone. Here, we hypothesize that high K⁺ cardioplegia (CP) plus MCG would provide added protection of mitochondrial bioenergetics and cardiac function against IR injury. Using fluorescence spectrophotometry, we monitored redox balance, ie reduced nicotinamide adenine dinucleotide and flavin adenine dinucleotide (NADH/FAD), superoxide (O₂ ^•−), and mitochondrial Ca²⁺ (m[Ca²⁺]) in the left ventricular free …

Subclinical Photoreceptor Disruption In Response To Severe Head Trauma, Kimberly E. Stepien, Wanda M. Martinez, Adam M. Dubis, Robert F. Cooper, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Commotio retinae is a transient opacification of the retina due to outer retinal disruption occurring in a contrecoup fashion after blunt trauma.Histological studies in animals and humans after ocular blunt trauma have revealed that disruption occurs at the level of the photoreceptor outer segments and retinal pigment epithelium.Recent reports using optical coherence tomography (OCT) have shown detectable disruption at the level of the photoreceptor inner segment/outer segment junction and retinal pigment epithelium and that these changes may be reversible over time with restoration of normal outer retinal architecture.However, the resolution of existing OCT technology may not be sensitive enough to …

Persistent Vascular Collagen Accumulation Alters Hemodynamic Recovery From Chronic Hypoxia, Diana M. Tabima, Alejandro Roldan-Alzate, Zhijie Wang, Timothy A. Hacker, Robert C. Molthen, Naomi C. Chesler

Biomedical Engineering Faculty Research and Publications

Pulmonary arterial hypertension (PAH) is caused by narrowing and stiffening of the pulmonary arteries that increase pulmonary vascular impedance (PVZ). In particular, small arteries narrow and large arteries stiffen. Large pulmonary artery (PA) stiffness is the best current predictor of mortality from PAH. We have previously shown that collagen accumulation leads to extralobar PA stiffening at high strain (Ooi et al. 2010). We hypothesized that collagen accumulation would increase PVZ, including total pulmonary vascular resistance (Z₀), characteristic impedance (Z_C), pulse wave velocity (PWV) and index of global wave reflections (P_b/P …

Damage To Mitochondrial Complex I During Cardiac Ischemia Reperfusion Injury Is Reduced Indirectly By Anti-Anginal Drug Ranolazine, Ashish K. Gadicherla, David F. Stowe, William E. Antholine, Meiying Yang, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

Ranolazine, an anti-anginal drug, is a late Na⁺ channel current blocker that is also believed to attenuate fatty acid oxidation and mitochondrial respiratory complex I activity, especially during ischemia. In this study, we investigated if ranolazine's protective effect against cardiac ischemia/reperfusion (IR) injury is mediated at the mitochondrial level and specifically if respiratory complex I (NADH Ubiquinone oxidoreductase) function is protected. We treated isolated and perfused guinea pig hearts with ranolazine just before 30 min ischemia and then isolated cardiac mitochondria at the end of 30 min ischemia and/or 30 min ischemia followed by 10 min reperfusion. We utilized …

Enhanced Charge-Independent Mitochondrial Free Ca2+ And Attenuated Adp-Induced Nadh Oxidation By Isoflurane: Implications For Cardioprotection, Bhawana Agarwal, Amadou K.S. Camara, David F. Stowe, Zeljko J. Bosnjak, Ranjan K. Dash

Biomedical Engineering Faculty Research and Publications

Modulation of mitochondrial free Ca^{2 +} ([Ca^{2 +}]_m) is implicated as one of the possible upstream factors that initiates anesthetic-mediated cardioprotection against ischemia–reperfusion (IR) injury. To unravel possible mechanisms by which volatile anesthetics modulate [Ca^{2 +}]_m and mitochondrial bioenergetics, with implications for cardioprotection, experiments were conducted to spectrofluorometrically measure concentration-dependent effects of isoflurane (0.5, 1, 1.5, 2 mM) on the magnitudes and time-courses of [Ca^{2 +}]_m and mitochondrial redox state (NADH), membrane potential (ΔΨ_m), respiration, and matrix volume. Isolated mitochondria from rat hearts were energized with 10 …

Analyzing Logistic Map Pseudorandom Number Generators For Periodicity Induced By Finite Precision Floating-Point Representation, Kyle Persohn, Richard J. Povinelli

Electrical and Computer Engineering Faculty Research and Publications

Because of the mixing and aperiodic properties of chaotic maps, such maps have been used as the basis for pseudorandom number generators (PRNGs). However, when implemented on a finite precision computer, chaotic maps have finite and periodic orbits. This manuscript explores the consequences finite precision has on the periodicity of a PRNG based on the logistic map. A comparison is made with conventional methods of generating pseudorandom numbers. The approach used to determine the number, delay, and period of the orbits of the logistic map at varying degrees of precision (3 to 23 bits) is described in detail, including the …

Biomechanics, Brooke A. Slavens, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Biomechanics is a vast discipline within the field of Biomedical Engineering. It explores the underlying mechanics of how biological and physiological systems move. It encompasses important clinical applications to address questions related to medicine using engineering mechanics principles. Biomechanics includes interdisciplinary concepts from engineers, physicians, therapists, biologists, physicists, and mathematicians. Through their collaborative efforts, biomechanics research is ever changing and expanding, explaining new mechanisms and principles for dynamic human systems. Biomechanics is used to describe how the human body moves, walks, and breathes, in addition to how it responds to injury and rehabilitation. Advanced biomechanical modeling methods, such as inverse …

An Empirical Method For Correcting The Detector Spectral Response In Energy-Resolved Ct, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Energy-resolving photon-counting detectors have the potential for improved material decomposition compared to dual-kVp approaches. However, material decomposition accuracy is limited by the nonideal spectral response of the detectors. This work proposes an empirical method for correcting the nonideal spectral response, including spectrum-tailing effects. Unlike previous correction methods which relied on synchrotron measurements, the proposed method can be performed on the scanner. The proposed method estimates a spectral-response matrix by performing x-ray projection measurements through a range of known thicknesses of two or more calibration materials. Once estimated, the spectral-response matrix is incorporated into conventional material decomposition algorithms. A simulation study …

Locomotor Adaptation To Resistance During Treadmill Training Transfers To Overground Walking In Human Sci, Sheng-Che Yen, Brian D. Schmit, Jill M. Landry, Heidi Roth, Ming Wu

Biomedical Engineering Faculty Research and Publications

Treadmill training has been used as a promising technique to improve overground walking in patients with spinal cord injury (SCI). Previous findings showed that a gait pattern may adapt to a force perturbation during treadmill training and show aftereffects following removal of the force perturbation. We hypothesized that aftereffects would transfer to overground walking to a greater extent when the force perturbation was resisting rather than assisting leg swing during treadmill training. Ten subjects with incomplete SCI were recruited into this study for two treadmill training sessions: one using swing resistance and the other using swing assistance during treadmill stepping. …

Distributed Multichannel Speech Enhancement With Minimum Mean-Square Error Short-Time Spectral Amplitude, Log-Spectral Amplitude, And Spectral Phase Estimation, Marek B. Trawicki, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

In this paper, the authors present optimal multichannel frequency domain estimators for minimum mean-square error (MMSE) short-time spectral amplitude (STSA), log-spectral amplitude (LSA), and spectral phase estimation in a widely distributed microphone configuration. The estimators utilize Rayleigh and Gaussian statistical models for the speech prior and noise likelihood with a diffuse noise field for the surrounding environment. Based on the Signal-to-Noise Ratio (SNR) and Segmental Signal-to-Noise Ratio (SSNR) along with the Log-Likelihood Ratio (LLR) and Perceptual Evaluation of Speech Quality (PESQ) as objective metrics, the multichannel LSA estimator decreases background noise and speech distortion and increases speech quality compared to …

Dataglove Measurement Of Joint Angles In Sign Language Handshapes, Petra Eccarius, Rebecca Bour, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

In sign language research, we understand little about articulatory factors involved in shaping phonemic boundaries or the amount (and articulatory nature) of acceptable phonetic variation between handshapes. To date, there exists no comprehensive analysis of handshape based on the quantitative measurement of joint angles during sign production. The purpose of our work is to develop a methodology for collecting and visualizing quantitative handshape data in an attempt to better understand how handshapes are produced at a phonetic level. In this pursuit, we seek to quantify the flexion and abduction angles of the finger joints using a commercial data glove (CyberGlove; …

Exploring Functional Networks Of The Brain Relating To Upper Extremity Motor Skill Using Graph Theory, Dominic Nathan, Stephen J. Guastello, Robert W. Prost, Dean C. Jeutter

Biomedical Engineering Faculty Research and Publications

No abstract provided.

The Effect Of Thermal Hydrolysis Pretreatment On The Anaerobic Degradation Of Nonylphenol And Short-Chain Nonylphenol Ethoxylates In Digested Biosolids, Patrick J. Mcnamara, C. A. Wilson, M. T. Wogen, S. N. Murthy, J. T. Novak, Paige J. Novak

Civil and Environmental Engineering Faculty Research and Publications

The presence of micropollutants can be a concern for land application of biosolids. Of particular interest are nonylphenol diethoxylate (NP₂EO), nonylphenol monoethoxylate (NP₁EO), and nonylphenol (NP), collectively referred to as NPE, which accumulate in anaerobically digested biosolids and are subject to regulation based on the environmental risks associated with them. Because biosolids are a valuable nutrient resource, it is essential that we understand how various treatment processes impact the fate of NPE in biosolids. Thermal hydrolysis (TH) coupled with mesophilic anaerobic digestion (MAD) is an advanced digestion process that destroys pathogens in biosolids and increases methane …

Characteristics Of Laterally Vibrating Resonant Microcantilevers In Viscous Liquid Media, Russell Cox, Fabien Josse, Stephen M. Heinrich, Oliver Brand, Isabelle Dufour

Civil and Environmental Engineering Faculty Research and Publications

The characteristics of microcantilevers vibrating laterally in viscous liquid media are investigated and compared to those of similar microcantilevers vibrating in the out-of-plane direction. The hydrodynamic loading on the vibrating beam is first determined using a numerical model. A semi-analytical expression for the hydrodynamic forces in terms of the Reynolds number and the aspect ratio (beam thickness over beam width) is obtained by introducing a correction factor to Stokes’ solution for a vibrating plate of infinite area to account for the effects of the thickness. The results enable the effects of fluid damping and effective fluid mass on the resonant …

Tracking Articulator Movements Using Orientation Measurements, An Ji, Michael T. Johnson, Jeffrey J. Berry

Speech Pathology and Audiology Faculty Research and Publications

This paper introduces a new method to track articulator movements, specifically jaw position and angle, using 5 degree of freedom (5 DOF) orientation data. The approach uses a quaternion rotation method to accomplish this jaw tracking during speech using a single senor on the mandibular incisor. Data were collected using the NDI Wave Speech Research System for one pilot subject with various speech tasks. The degree of jaw rotation from the proposed approach is compared with traditional geometric calculation. Results show that the quaternion based method is able to describe jaw angle trajectory and gives more accurate and smooth estimation …

Upper Extremity Kinematics In Children With Spinal Cord Injury During Wheelchair Mobility, Brooke Slavens, Alyssa Paul, Adam Graf, Joseph Krzak, Lawrence Vogel, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Foot And Ankle Motion Analysis Using Dynamic Radiographic (Fluoroscopic) Imaging, Benjamin Mchenry, Jason T. Long, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Estimation Of Organ And Effective Dose Due To Compton Backscatter Security Scans, Michael Hoppe, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose: To estimate organ and effective radiation doses due to backscatter security scanners using Monte Carlo simulations and a voxelized phantom set. Methods: Voxelized phantoms of male and female adults and children were used with the GEANT4 toolkit to simulate a backscatter security scan. The backscatter system was modeled based on specifications available in the literature. The simulations modeled a 50 kVp spectrum with 1.0 mm-aluminum-equivalent filtration and a previously measured exposure of approximately 4.6 μR at 30 cm from the source. Photons and secondary interactions were tracked from the source until they reached zero kinetic energy or exited from …

Are Posture Data From Simulated Tasks Representative Of Field Conditions? Case Study For Overhead Electric Utility Workers, Cristiane Shinohara Moriguichi, Leticia Carnaz, Luiz Carlos De Miranda Jr, Richard W. Marklin, Helenice Jane Cote Gil Coury

Mechanical Engineering Faculty Research and Publications

Many ergonomics studies are conducted in laboratory-simulated work environments to assess risks for the development of musculoskeletal disorders under more controlled conditions. However, the simulated conditions could be of questionable validity with respect to reproduction of field conditions involving risk factors. The objective of this study was to verify whether the postures recorded for neck extension/flexion and upper arm elevation of overhead electric utility workers in a simulated environment were similar to those recorded in a field environment. Of the three frequently performed tasks analysed, two presented similar exposure in both conditions. However, differences were identified for a more complex …

An In Vitro Comparative Study Of Intracanal Fluid Motion And Wall Shear Stress Induced By Ultrasonic And Polymer Rotary Finishing Files In A Simulated Root Canal Model, Jon Koch, John Borg, Abby Mattson, Kris Olsen, James Bahcall

Mechanical Engineering Faculty Research and Publications

Objective. This in vitro study compared the flow pattern and shear stress of an irrigant induced by ultrasonic and polymer rotary finishing file activation in an acrylic root canal model. Flow visualization analysis was performed using an acrylic canal filled with a mixture of distilled water and rheoscopic fluid. The ultrasonic and polymer rotary finishing file were separately tested in the canal and activated in a static position and in a cyclical axial motion (up and down). Particle movement in the fluid was captured using a high-speed digital camera and DaVis 7.1 software. The fluid shear stress analysis was …

Characterizing Metal-Insulator-Transition (Mit) Phase Change Materials (Pcm) For Rf And Dc Micro-Switching Elements, Brent L. Danner, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

Metal-insulator transition (MIT) phase-change materials (PCM) are material compounds that have the ability to be either conductors or insulators depending on external stimuli. A micromachined test structure for applying external electric fields across MIT wire segments was designed and fabricated. Using this novel test structure, Germanium Telluride (GeTe) and Vanadium Oxide (VOx) were successfully transitioned from a conductor to an insulator. The resistivity of the GeTe wire segments increased three to five orders of magnitude with ∼40 V applied to the parallel plates of the test structure. The VOx wires exhibited an order of magnitude transition in resistivity with ∼20 …

Continuous Time-Varying Biasing Approach For Spectrally Tunable Infrared Detectors, Woo-Yong Jang, Majeed M. Hayat, Payman Zarkesh-Ha, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

In a recently demonstrated algorithmic spectral-tuning technique by Jang et al. [Opt. Express 19, 19454-19472, (2011)], the reconstruction of an object’s emissivity at an arbitrarily specified spectral window of interest in the long-wave infrared region was achieved. The technique relied upon forming a weighted superposition of a series of photocurrents from a quantum dots-in-a-well (DWELL) photodetector operated at discrete static biases that were applied serially. Here, the technique is generalized such that a continuously varying biasing voltage is employed over an extended acquisition time, in place using a series of fixed biases over each sub-acquisition time, which totally …

A New Ensemble Learning Method For Temporal Pattern Identification, Wenjing Zhang, Xin Feng

Electrical and Computer Engineering Faculty Research and Publications

In this paper we present a method for identification of temporal patterns predictive of significant events in a dynamic data system. A new hybrid model using Reconstructed Phase Space (MRPS) and Hidden Markov Model (HMM) is applied to identify temporal patterns. This method constructs phase space embedding by using individual embedding of each variable sequences. We also employ Hidden Markov Models (HMM) to the multivariate sequence data to categorize multi-dimensional data into three states, e.g. normal, patterns and events. A support vector machine optimization method is used to search an optimal classifier to identify temporal patterns that are predictive of …

New Perspective On Passively Quenched Single Photon Avalanche Diodes: Effect Of Feedback On Impact Ionization, David A. Ramirez, Majeed M. Hayat, Graham J. Rees, Xudong Jiang, Mark A. Itzler

Electrical and Computer Engineering Faculty Research and Publications

Single-photon avalanche diodes (SPADs) are primary devices in photon counting systems used in quantum cryptography, time resolved spectroscopy and photon counting optical communication. SPADs convert each photo-generated electron hole pair to a measurable current via an avalanche of impact ionizations. In this paper, a stochastically self-regulating avalanche model for passively quenched SPADs is presented. The model predicts, in qualitative agreement with experiments, three important phenomena that traditional models are unable to predict. These are: (1) an oscillatory behavior of the persistent avalanche current; (2) an exponential (memoryless) decay of the probability density function of the stochastic quenching time of the …