Engineering Commons^™

Segmental Kinematic Assessment Of Pediatric Pes Planovalgus With Radiographic Skeletal Indexing, Katherine A. Konop, Jason T. Long, Joseph Krzak, Adam Graf, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Assessing Spinal Motion At Different Fusion Levels In Adolescents With Idiopathic Scoliosis, Sahar Hassani, Adam Graf, Joseph Krzak, K. Hammerberg, P. Sturm, P. Gupta, M. Riordan, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Long-Term Follow Up Of Van Nes Rotationplasty For Proximal Focal Femoral Deficiency, Haluk Altiok, Jeffrey D. Ackman, Ann Flanagan, Mary Peer, Adam Graf, Joseph Krzak, Sahar Hassani, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Proximal focal femoral deficiency (PFFD) is a congenital anomaly that presents challenges for orthopaedic and prosthetic management. The Van Nes rotationplasty is one treatment in which the extremity is surgically rotated to utilize the ankle and foot as a functional knee joint in a prosthesis. The purpose of this study is to determine the long-term functional and quality of life (QOL) outcomes for individuals who have undergone rotationplasty surgery for congenital PFFD compared to age and gender matched controls.

Including Aortic Valve Morphology In Computational Fluid Dynamics Simulations: Initial Findings And Application To Aortic Coarctation, David C. Wendell, Margaret M. Samyn, Joseph Richard Cava, Laura M. Ellwein, Mary M. Krolikowski, Kimberly L. Gandy, Andrew N. Pelech, Shawn C. Shadden, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Computational fluid dynamics (CFD) simulations quantifying thoracic aortic flow patterns have not included disturbances from the aortic valve (AoV). 80% of patients with aortic coarctation (CoA) have a bicuspid aortic valve (BAV) which may cause adverse flow patterns contributing to morbidity. Our objectives were to develop a method to account for the AoV in CFD simulations, and quantify its impact on local hemodynamics. The method developed facilitates segmentation of the AoV, spatiotemporal interpolation of segments, and anatomic positioning of segments at the CFD model inlet. The AoV was included in CFD model examples of a normal (tricuspid AoV) and a …

Long-Term Follow Up Of Van Nes Rotationplasty For Congenital Proximal Focal Femoral Deficiency [Proceedings], Haluk Altiok, Jeffrey D. Ackman, Ann Flanagan, Mary Peer, Adam Graf, Joseph Krzak, Sahar Hassani, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

INTRODUCTION: Proximal focal femoral deficiency (PFFD) is a congenital anomaly that presents challenges for orthopaedic and prosthetic management. The Van Nes rotationplasty is one treatment in which the extremity is surgically rotated to utilize the ankle and foot as a functional knee joint in a prosthesis. The purpose of this study is to determine the long-term functional and quality of life (QOL) outcomes for individuals who have undergone rotationplasty surgery for congenital PFFD compared to age and gender matched controls.

METHODS: This prospective study had 12 prosthetic participants (PFFD Group: 8 M, 4F, age range 16-57 years) average 31.6±13.5 years …

Multisegmental Foot And Ankle Motion Analysis After Hallux Valgus Surgery, Karl Canseco, Jason T. Long, Thomas Smedberg, Sergey Tarima, Richard Marks, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background: Gait changes in patients with hallux valgus, including altered kinematic and temporal-spatial parameters, have been documented in the literature. Although operative treatment can yield favorable clinical and radiographic results, restoration of normal gait in this population remains unclear. Segmental kinematic changes within the foot and ankle during ambulation after operative correction of hallux valgus have not been reported. The aim of this study was to analyze changes in multisegmental foot and ankle kinematics in patients who underwent operative correction of hallux valgus. Methods: A 15-camera Vicon Motion Analysis System was used to evaluate 24 feet in 19 patients with …

A Suspended Nanogap Formed By Field-Induced Atomically Sharp Tips, Jun Hyun Han, Kyung Song, Shankar Radhakrishnan, Sang Ho Oh, Chung Hoon Lee

Electrical and Computer Engineering Faculty Research and Publications

A sub-nanometer scale suspended gap (nanogap) defined by electric field-induced atomically sharp metallic tips is presented. A strong local electric field (>109 V=m) across micro/nanomachined tips facing each other causes the metal ion migration in the form of dendrite-like growth at the cathode. The nanogap is fully isolated from the substrate eliminating growth mechanisms that involve substrate interactions. The proposed mechanism of ion transportation is verified using real-time imaging of the metal ion transportation using an in situ biasing in transmission electron microscope (TEM). The configuration of the micro/nanomachined suspended tips allows nanostructure growth of a wide variety of …

Remembering Forward: Neural Correlates Of Memory And Prediction In Human Motor Adaptation, Robert A. Scheidt, Janice Zimbelman, Nicole M.G. Salowitz, Aaron J. Suminski, Kristine M. Mosier, James Houk, Lucia Simo

Biomedical Engineering Faculty Research and Publications

We used functional MR imaging (FMRI), a robotic manipulandum and systems identification techniques to examine neural correlates of predictive compensation for spring-like loads during goal-directed wrist movements in neurologically-intact humans. Although load changed unpredictably from one trial to the next, subjects nevertheless used sensorimotor memories from recent movements to predict and compensate upcoming loads. Prediction enabled subjects to adapt performance so that the task was accomplished with minimum effort. Population analyses of functional images revealed a distributed, bilateral network of cortical and subcortical activity supporting predictive load compensation during visual target capture. Cortical regions – including prefrontal, parietal and hippocampal …

A Database For Estimating Organ Dose For Chest And Head Ct Scans For Arbitrary Spectra And Angular Tube Current Modulation, Franco Rupcich, Andreu Badal, Iacovos Kyprianou, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose: The purpose of this study was to develop a database for estimating organ dose in a voxelized patient model for coronary angiography and brain perfusion CT acquisitions with any spectra and angular tube current modulation setting. The database enables organ dose estimation for existing and novel acquisition techniques without requiring Monte Carlo simulations. Methods: The study simulated transport of monoenergetic photons between 5 and 150 keV for 1000 projections over 360◦ through anthropomorphic voxelized female chest and head (0◦ and 30◦ tilt) phantoms and standard head and body CTDI dosimetry cylinders. The simulations resulted in tables of normalized dose …

A Very Robust Algan/Gan Hemt Technology To High Forward Gate Bias And Current, Bradley D. Christiansen, Eric R. Heller, Ronald A. Coutu Jr., Ramakrishna Vetury, Jeffrey B. Shealy

Electrical and Computer Engineering Faculty Research and Publications

Reports to date of GaN HEMTs subjected to forward gate bias stress include varied extents of degradation. We report an extremely robust GaN HEMT technology that survived—contrary to conventional wisdom—high forward gate bias (+6 V) and current (>1.8 A/mm) for >17.5 hours exhibiting only a slight change in gate diode characteristic, little decrease in maximum drain current, with only a 0.1 V positive threshold voltage shift, and, remarkably, a persisting breakdown voltage exceeding 200 V.

A Mems Photoacoustic Detector Of Terahertz Radiation For Chemical Sensing, Nathan Glauvitz, S. Blazevic, Ronald A. Coutu Jr., Michael Kistler, Ivan R. Medvedev, Douglas T. Petkie

Electrical and Computer Engineering Faculty Research and Publications

A piezoelectric Microelectromechanical system (MEMS) cantilever pressure sensor was designed, modeled, fabricated, and tested for sensing the photoacoustic response of gases to terahertz (THz) radiation. The sensing layers were comprised of three thin films; a lead zirconate titanate (PZT) piezoelectric layer sandwiched between two metal contact layers. The sensor materials were deposited on the silicon device layer of a silicon-on-insulator (SOI) wafer, which formed the physical structure of the cantilever. To release the cantilever, a hole was etched through the backside of the wafer and the buried oxide was removed with hydrofluoric acid. Devices were then tested in a custom …

Multiplication Theory For Dynamically Biased Avalanche Photodiodes: New Limits For Gain Bandwidth Product, Majeed M. Hayat, David A. Ramirez

Electrical and Computer Engineering Faculty Research and Publications

Novel theory is developed for the avalanche multiplication process in avalanche photodiodes (APDs) under time-varying reverse-biasing conditions. Integral equations are derived characterizing the statistics of the multiplication factor and the impulse-response function of APDs, as well as their breakdown probability, all under the assumption that the electric field driving the avalanche process is time varying and spatially nonuniform. Numerical calculations generated by the model predict that by using a bit-synchronous sinusoidal biasing scheme to operate the APD in an optical receiver, the pulse-integrated gain-bandwidth product can be improved by a factor of 5 compared to the same APD operating under …

Quantifying The Tibiofemoral Joint Space Using X-Ray Tomosynthesis, Benjamin Kalinosky, John M. Sabol, Kelly Piacsek, Beth Heckel, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose: Digital x-ray tomosynthesis (DTS) has the potential to provide 3D information about the knee joint in a load-bearing posture, which may improve diagnosis and monitoring of knee osteoarthritis compared with projection radiography, the current standard of care. Manually quantifying and visualizing the joint space width (JSW) from 3D tomosynthesis datasets may be challenging. This work developed a semiautomated algorithm for quantifying the 3D tibiofemoral JSW from reconstructed DTS images. The algorithm was validated through anthropomorphic phantom experiments and applied to three clinical datasets. Methods: A user-selected volume of interest within the reconstructed DTS volume was enhanced with 1D multiscale …

Mechanical Characterization Of Fourth Generation Composite Humerus, Prateek Grover, Carolyne Albert, Mei Wang, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Mechanical data on upper extremity surrogate bones, supporting use as biomechanical tools, is limited. The objective of this study was to characterize the structural behaviour of the fourth-generation composite humerus under simulated physiologic bending, specifically, stiffness, rigidity, and mid-diaphysial surface strains. Three humeri were tested in four-point bending, in anatomically defined anteroposterior (AP) and mediolateral (ML) planes. Stiffness and rigidity were derived using load–displacement data. Principal strains were determined at the anterior, posterior, medial, and lateral surfaces in the humeral mid-diaphysial transverse plane of one specimen using stacked rosettes. Linear structural behaviour was observed within the test range. Average stiffness …

Different Motion Cues Are Used To Estimate Time-To-Arrival For Frontoparallel And Loming Trajectories, Finnegan J. Calabro, Scott A. Beardsley, Lucia M. Vaina

Biomedical Engineering Faculty Research and Publications

Estimation of time-to-arrival for moving objects is critical to obstacle interception and avoidance, as well as to timing actions such as reaching and grasping moving objects. The source of motion information that conveys arrival time varies with the trajectory of the object raising the question of whether multiple context-dependent mechanisms are involved in this computation. To address this question we conducted a series of psychophysical studies to measure observers’ performance on time-to-arrival estimation when object trajectory was specified by angular motion (“gap closure” trajectories in the frontoparallel plane), looming (colliding trajectories, TTC) or both (passage courses, TTP). We measured performance …

High Temperature Thermodynamic Properties Of Znte(S), Robert F. Brebrick

Mechanical Engineering Faculty Research and Publications

We have gathered the partial pressure, Knudsen cell, and emf measurements on ZnTe(s) from which the Gibbs energy of formation can be calculated. Published partial pressures of diatomic tellurium have been adjusted to take account of a subsequently published third law analysis of tellurium. The equation used to calculate the total pressure from the rate of mass loss from an extensive set of Knudsen cell measurements has been corrected to give a 5% increase in total pressure and the Gibbs energy of formation has been recalculated. A high temperature heat capacity for ZnTe(s) has been selected from the published data. …

Sensing With The Motor Cortex, Nicholas G. Hatsopoulos, Aaron J. Suminski

Biomedical Engineering Faculty Research and Publications

The primary motor cortex is a critical node in the network of brain regions responsible for voluntary motor behavior. It has been less appreciated, however, that the motor cortex exhibits sensory responses in a variety of modalities including vision and somatosensation. We review current work that emphasizes the heterogeneity in sensorimotor responses in the motor cortex and focus on its implications for cortical control of movement as well as for brain-machine interface development.

Effect Of Sensory Feedback From The Proximal Upper Limb On Voluntary Isometric Finger Flexion And Extension In Hemiparetic Stroke Subjects, Gilles Hoffmann, Brian D. Schmit, Jennifer H. Kahn, Derek G. Kamper

Biomedical Engineering Faculty Research and Publications

This study investigated the potential influence of proximal sensory feedback on voluntary distal motor activity in the paretic upper limb of hemiparetic stroke survivors and the potential effect of voluntary distal motor activity on proximal muscle activity. Ten stroke subjects and 10 neurologically intact control subjects performed maximum voluntary isometric flexion and extension, respectively, at the metacarpophalangeal (MCP) joints of the fingers in two static arm postures and under three conditions of electrical stimulation of the arm. The tasks were quantified in terms of maximum MCP torque [MCP flexion (MCP_flex) or MCP extension (MCP_ext)] and activity …

Patterns Of Hypermetria And Terminal Cocontraction During Point-To-Point Movements Demonstrate Independent Action Of Trajectory And Postural Controllers, Robert A. Scheidt, Claude Ghez, Supriya Asnani

Biomedical Engineering Faculty Research and Publications

We examined elbow muscle activities and movement kinematics to determine how subjects combine elementary control actions in performing movements with one and two trajectory segments. In reaching, subjects made a rapid elbow flexion to a visual target before stabilizing the limb with either a low or a higher level of elbow flexor/extensor coactivity (CoA), which was cued by target diameter. Cursor diameter provided real-time biofeedback of actual muscle CoA. In reversing, the limb was to reverse direction within the target and return to the origin with minimal CoA. We previously reported that subjects overshoot the goal when attempting a reversal …

Gait Verification Using Knee Acceleration Signals, L. W. Hang, C. Y. Hong, C. W. Yen, D. J. Chang, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

A novel gait recognition method for biometric applications is proposed. The approach has the following distinct features. First, gait patterns are determined via knee acceleration signals, circumventing difficulties associated with conventional vision-based gait recognition methods. Second, an automatic procedure to extract gait features from acceleration signals is developed that employs a multiple-template classification method. Consequently, the proposed approach can adjust the sensitivity and specificity of the gait recognition system with great flexibility. Experimental results from 35 subjects demonstrate the potential of the approach for successful recognition. By setting sensitivity to be 0.95 and 0.90, the resulting specificity ranges from 1 …

Electrostatically Tunable Meta-Atoms Integrated With In Situ Fabricated Mems Cantilever Beam Arrays, Ronald A. Coutu Jr., Peter J. Collins, Elizabeth A. Moore, Derrick Langley, Matthew E. Jussaume, Lavern A. Starman

Electrical and Computer Engineering Faculty Research and Publications

Two concentric split ring resonators (SRRs) or meta-atoms designed to have a resonant frequency of 14 GHz are integrated with microelectromechanical systems cantilever arrays to enable electrostatic tuning of the resonant frequency. The entire structure was fabricated monolithically to improve scalability and minimize losses from externally wire-bonded components. A cantilever array was fabricated in the gap of both the inner and outer SRRs and consisted of five evenly spaced beams with lengths ranging from 300 to 400 μm. The cantilevers pulled in between 15 and 24 V depending on the beam geometry. Each pulled-in beam increased the SRR gap capacitance …

A Quantitative Study Of Robustness Characteristics In Steel Framed Structures, Christopher Herman Raebel

Dissertations (1934 -)

Robustness is a desirable property in any structural design. Robustness may be thought of as the building's inherent structural ability to resist loads other than those anticipated during design. Examples of unanticipated loads are damage to a column or beam due to impact; damage due to the concussion of a blast; strength reduction due to extreme heat during a fire; and localized accidental overload of a beam or column. Each of these events, although very different in their nature, has one major point in common; in each case the path of load resistance changes in a way that was not …

Investigation Of Aluminum Equation Of State Generation, Aaron Ward

Master's Theses (2009 -)

There are many forms and methods to construct equations of state, EOSs. These methods are usually tailored for the particular problem of interest. Here, the EOSs of interest are those used in modeling shock responses. These EOSs cover a wide range of physical characteristics such as detonation and explosions, armor and anti-armor materials, and space structures protection. Aluminum will be the primary focus of this work. Aluminum was chosen because it has been studied in great length in the shock regime and is a common component in shock experiments and space type vehicles.

Improving Cardiovascular Stent Design Using Patient-Specific Models And Shape Optimization, Timothy J. Gundert

Master's Theses (2009 -)

Stent geometry influences local hemodynamic alterations (i.e. the forces moving blood through the cardiovascular system) associated with adverse clinical outcomes. Computational fluid dynamics (CFD) is frequently used to quantify stent-induced hemodynamic disturbances, but previous CFD studies have relied on simplified device or vascular representations. Additionally, efforts to minimize stent-induced hemodynamic disturbances using CFD models often only compare a small number of possible stent geometries. This thesis describes methods for modeling commercial stents in patient-specific vessels along with computational techniques for determining optimal stent geometries that address the limitations of previous studies.

An efficient and robust method was developed for virtually …

Analysis Of An Air-Spaced Patch Antenna Near 1800 Mhz, Hermine Nathalie Akouemo Kengmo Kenfack

Master's Theses (2009 -)

Microstrip antennas are a type of printed antenna which consists of a patch on top of a grounded substrate. A major limitation for the performance of the patch antenna is the dielectric substrate. The idea of using air as dielectric was therefore considered to overcome that limitation because air has the lowest permittivity and no loss. The goal of this work is to build an air-spaced patch antenna, with the minimum resonant frequency at 1800 MHz and with a return loss of at least 10 dB.

This work is novel because the air-spaced patch antenna has not been extensively studied. …

Disaggregating Time Series Data For Energy Consumption By Aggregate And Individual Customer, Steven Vitullo

Dissertations (1934 -)

This dissertation generalizes the problem of disaggregating time series data and describes the disaggregation problem as a mathematical inverse problem that breaks up aggregated (measured) time series data that is accumulated over an interval and estimates its component parts.

We describe five different algorithms for disaggregating time series data: the Naive, Time Series Reconstruction (TSR), Piecewise Linear Optimization (PLO), Time Series Reconstruction with Resampling (RS), and Interpolation (INT). The TSR uses least squares and domain knowledge of underlying correlated variables to generate underlying estimates and handles arbitrarily aggregated time steps and non-uniformly aggregated time steps. The PLO performs an adjustment …

Stability And Minimum Cost Analysis Of A Discrete-Time Disturbance Accommodation Controller, Katrina H. Barhouse

Master's Theses (2009 -)

Disturbance accommodation control (DAC) is a method for designing a controller that minimizes the effects of disturbances of known waveform type, but with unknown arrival time, duration or magnitude. Systems that do not have a control term in the measurement equation pose a particular challenge for DAC design. A disturbance accommodation controller for these types of systems was previously developed by defining a pseudo-output consisting of the current output and previous control input terms with weighting coefficients.

The objective of the present work is to analyze the stability and performance of the discrete- time disturbance accommodation controller for systems without …

Comparison Of An Ankle-Foot-Orthosis And Neuroprosthesis During Level And Non-Level Walking For Individuals Post-Stroke, Michelle Beverly Gallagher

Master's Theses (2009 -)

This study used gait analysis to compare the efficacy of the two foot drop treatments (ankle-foot-orthosis and neuroprosthesis) and to contrast the stimulation control of the two different neuroprosthesis sensors during level and non-level ambulation of post-stroke individuals.

Eight subjects completed two gait analysis sessions, once while using a study-provided articulated AFO and the other while using a WalkAide. After four weeks of acclimation to the device, each subject performed two minute walking trials on a level, inclined and declined treadmill. Kinematic and heart rate data were collected for all sessions. Plantar pressure and WalkAide tilt, heel loading, and stimulation …

Droplet Behavior In Dense, Low Velocity Aerosols, Alexander Polley

Master's Theses (2009 -)

Rapid compression machines (RCM) are laboratory devices used to measure gas-phase fuel reactivity at conditions relevant to combustion engines. Test mixtures are generally prepared by rapidly compressing a gas phase fuel+oxidizer+diluent mixture to high pressure and temperature (e.g., 10-50 bar, 650-1000 K). It is extremely challenging to utilize diesel-relevant liquid fuels in these devices due to their involatility. One proposed method involves the delivery of an aerosol of suspended fuel droplets (∼ 0.1 mL_fuel/L_gas at stoichiometric fuel loading) to the machine. The compression stroke of the RCM subsequently heats the gas phase of the aerosol thereby achieving …

Motion Analysis Of The Upper Extremities During Lofstrand Crutch-Assisted Gait In Children With Orthopaedic Disabilities, Brooke A. Slavens, Neha Bhagchandani, Mei Wang, Peter A. Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background

This paper presents a review of current state-of-the-art dynamic systems for quantifying the kinematics and kinetics of the joints of the upper extremities during Lofstrand crutch-assisted gait. The reviewed systems focus on the rehabilitation of children and adults with myelomeningocele (MM), cerebral palsy (CP), spinal cord injury (SCI), and osteogenesis imperfecta (OI). Forearm crutch systems have evolved from models with single- to multi-sensor hardware systems that can incorporate an increasing number of segments that are in compliance with the standards of the International Society of Biomechanics (ISB).

Methods

The initial system developed by our group was a single, six-axis, …