Engineering Commons^™

Optimization Of Inp Apds For High-Speed Lightwave Systems, Daniel S.G. Ong, Jo Shien Ng, Majeed M. Hayat, John P.R. David

Electrical and Computer Engineering Faculty Research and Publications

Calculations based on a rigorous analytical model are carried out to optimize the width of the indium phosphide avalanche region in high-speed direct-detection avalanche photodiode-based optical receivers. The model includes the effects of intersymbol interference (ISI), tunneling current, avalanche noise, and its correlation with the stochastic avalanche duration, as well as dead space. A minimum receiver sensitivity of -28 dBm is predicted at an optimal width of 0.18 mum and an optimal gain of approximately 13, for a 10 Gb/s communication system, assuming a Johnson noise level of 629 noise electrons per bit. The interplay among the factors controlling the …

Efficient Embedded Speech Recognition For Very Large Vocabulary Mandarin Car-Navigation Systems, Yanmin Qian, Jia Liu, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

Automatic speech recognition (ASR) for a very large vocabulary of isolated words is a difficult task on a resource-limited embedded device. This paper presents a novel fast decoding algorithm for a Mandarin speech recognition system which can simultaneously process hundreds of thousands of items and maintain high recognition accuracy. The proposed algorithm constructs a semi-tree search network based on Mandarin pronunciation rules, to avoid duplicate syllable matching and save redundant memory. Based on a two-stage fixed-width beam-search baseline system, the algorithm employs a variable beam-width pruning strategy and a frame-synchronous word-level pruning strategy to significantly reduce recognition time. This algorithm …

Discriminating Pulmonary Hypertension Caused By Monocrotaline Toxicity From Chronic Hypoxia By Near-Infrared Spectroscopy And Multivariate Methods Of Analysis, Simon Duri, Robert C. Molthen, Chieu D. Tran

Biomedical Engineering Faculty Research and Publications

A new method has been developed for the determination of tissue pathology caused by chronic hypoxia and monocrotaline toxicity. The method is based on the use of near-infrared (NIR) spectrophotometry to measure spectra of lung tissue from normal chronic hypoxia (CH) and monocrotaline (MCT) models of pulmonary hypertension (PH), followed by analysis using multivariate methods, that is, principal component analysis (PCA) and partial least squares (PLS). Synergistic use of NIR with the PCA/PLS method makes it possible, for the first time, not only to divide different lung tissue samples into their respective groups (normal, CH, and MCT) but also to …

Optimal "Image-Based" Weighting For Energy-Resolved Ct, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

This paper investigates a method of reconstructing images from energy-resolved CT data with negligible beam-hardening artifacts and improved contrast-to-nosie [sic] ratio (CNR) compared to conventional energy-weighting methods. Conceptually, the investigated method first reconstructs separate images from each energy bin. The final image is a linear combination of the energy-bin images, with the weights chosen to maximize the CNR in the final image. The optimal weight of a particular energy-bin image is derived to be proportional to the contrast-to-noise-variance ratio in that image. The investigated weighting method is referred to as “image-based” weighting, although, as will be described, the weights can …

Elastic, Viscous, And Mass Load Effects On Poststroke Muscle Recruitment And Co-Contraction During Reaching: A Pilot Study, Tina M. Stoeckmann, Katherine J. Sullivan, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

Background: Resistive exercise after stroke can improve strength (force-generating capacity) without increasing spasticity (velocity-dependent hypertonicity). However, the effect of resistive load type on muscle activation and co-contraction after stroke is not clear.

Objective: The purpose of this study was to determine the effect of load type (elastic, viscous, or mass) on muscle activation and co-contraction during resisted forward reaching in the paretic and nonparetic arms after stroke.

Design: This investigation was a single-session, mixed repeated-measures pilot study.

Methods: Twenty participants (10 with hemiplegia and 10 without neurologic involvement) reached forward with each arm against equivalent elastic, viscous, and mass loads. …

Demonstration Of Bias-Controlled Algorithmic Tuning Of Quantum Dots In A Well (Dwell) Midir Detectors, Woo-Yong Jang, Majeed M. Hayat, J. Scott Tyo, Ram S. Attaluri, Thomas E. Vandervelde, Yagya D. Sharma, Rajeev Shenoi, Andreas Stintz, Elizabeth R. Cantwell, Steven C. Bender, Sang Jun Lee, Sam Kyu Noh, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

The quantum-confined Stark effect in intersublevel transitions present in quantum-dots-in-a-well (DWELL) detectors gives rise to a midIR spectral response that is dependent upon the detector's operational bias. The spectral responses resulting from different biases exhibit spectral shifts, albeit with significant spectral overlap. A postprocessing algorithm was developed by Sakoglu that exploited this bias-dependent spectral diversity to predict the continuous and arbitrary tunability of the DWELL detector within certain limits. This paper focuses on the experimental demonstration of the DWELL-based spectral tuning algorithm. It is shown experimentally that it is possible to reconstruct the spectral content of a target electronically without …

Mitochondrial Reactive Oxygen Species Production In Excitable Cells: Modulators Of Mitochondrial And Cell Function, David F. Stowe, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

The mitochondrion is a major source of reactive oxygen species (ROS). Superoxide (O₂^•−) is generated under specific bioenergetic conditions at several sites within the electron-transport system; most is converted to H₂O₂ inside and outside the mitochondrial matrix by superoxide dismutases. H₂O₂ is a major chemical messenger that, in low amounts and with its products, physiologically modulates cell function. The redox state and ROS scavengers largely control the emission (generation scavenging) of O₂^•−. Cell ischemia, hypoxia, or toxins can result in excess O₂^•− production when the redox …

Bioresorbable Film For The Prevention Of Adhesion To The Anterior Spine After Anterolateral Discectomy, Lisa S. Klopp, Jeffrey M. Toth, William C. Welch, Sangeeta Rao, Joseph W. Tai, Kevin A. Thomas, Simon Turner

Biomedical Engineering Faculty Research and Publications

Background context

The development of scar tissue and adhesions postoperatively is a natural consequence of healing but can be associated with medical complications and render reoperation difficult. Many biocompatible products have been evaluated as barriers or deterrents to adhesions.

Purpose

To evaluate the efficacy of a bioresorbable polylactide film as a barrier to adhesion formation after anterolateral discectomy.

Study design

Experimental study.

Methods

Seven, skeletally mature female sheep underwent a retroperitoneal approach to the anterolateral lumbar spine. A discectomy was performed at two levels with an intervening unoperated disc site. One site was treated with a polylactide film barrier (Hydrosorb …

Vascular Injury After Whole Thoracic X-Ray Irradiation In The Rat, S. N. Ghosh, Q. Wu, M. Mäder, B. L. Fish, John E. Moulder, Elizabeth R. Jacobs, Meetha Medhora, Robert C. Molthen

Biomedical Engineering Faculty Research and Publications

Purpose

To study vascular injury after whole thoracic irradiation with single sublethal doses of X-rays in the rat and to develop markers that might predict the severity of injury.

Methods and Materials

Rats that received 5- or 10-Gy thorax-only irradiation and age-matched controls were studied at 3 days, 2 weeks, and 1, 2, 5, and 12 months. Several pulmonary vascular parameters were evaluated, including hemodynamics, vessel density, total lung angiotensin-converting enzyme activity, and right ventricular hypertrophy.

Results

By 1 month, the rats in the 10-Gy group had pulmonary vascular dropout, right ventricular hypertrophy, increased pulmonary vascular resistance, increased dry lung …

Ankle Load Modulates Hip Kinetics And Emg During Human Locomotion, Keith E. Gordon, Ming Wu, Jennifer H. Kahn, Yasin Y. Dhaher, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

The purpose of this research was to examine the role of isolated ankle-foot load in regulating locomotor patterns in humans with and without spinal cord injury (SCI). We used a powered ankle-foot orthosis to unilaterally load the ankle and foot during robotically assisted airstepping. The load perturbation consisted of an applied dorsiflexion torque designed to stimulate physiological load sensors originating from the ankle plantar flexor muscles and pressure receptors on the sole of the foot. We hypothesized that 1) the response to load would be phase specific with enhanced ipsilateral extensor muscle activity and joint torque occurring when unilateral …

Analysis Of Load-Induced Strains In A Hot Mix Asphalt Perpetual Pavement, James Crovetti

Transportation Reports with the Wisconsin Department of Transportation

This report presents the findings of a research study conducted to investigate the structural performance of a 275 mm hot mix asphalt perpetual pavement constructed as part of the WIM bypass lane at the Kenosha Safety & Weigh Station Facility. Two separate test sections were constructed using variable binder types and in-place air voids. Asphalt strain sensors were fabricated at Marquette University and installed during the construction of the HMA pavement. Sensors were positioned within the outer wheel path and located at the bottom of the 275 mm HMA pavement and at the interface between the lower layers at a …

Auditory Coding Based Speech Enhancement, Yao Ren, Michael T. Johnson

Dr. Dolittle Project: A Framework for Classification and Understanding of Animal Vocalizations

This paper demonstrates a speech enhancement system based on an efficient auditory coding approach, coding of time-relative structure using spikes. The spike coding method can more compactly represent the non-stationary characteristics of speech signals than the Fourier transform or wavelet transform. Enhancement is accomplished through the use of MMSE thresholding on the spike code. Experimental results show that compared with the spectral domain logSTSA filter, both the subjective spectrogram evaluation and objective SSNR improvement for the proposed approach is better in suppressing noise in high noise situations, with fewer musical artifacts.P

Optimal Distributed Microphone Phase Estimation, Marek B. Trawicki, Michael T. Johnson

Dr. Dolittle Project: A Framework for Classification and Understanding of Animal Vocalizations

This paper presents a minimum mean-square error spectral phase estimator for speech enhancement in the distributed multiple microphone scenario. The estimator uses Gaussian models for both the speech and noise priors under the assumption of a diffuse incoherent noise field representing ambient noise in a widely dispersed microphone configuration. Experiments demonstrate significant benefits of using the optimal multichannel phase estimator as compared to the noisy phase of a reference channel.

A Comparison Of Pilot-Scale Photocatalysis And Enhanced Coagulation For Disinfection Byproduct Mitigation, Daniel Gerrity, Brooke K. Mayer, Hodon Ryu, John Crittenden, Morteza Abbaszadegan

Civil and Environmental Engineering Faculty Research and Publications

This study evaluated pilot-scale photocatalysis and enhanced coagulation for their ability to remove or destroy disinfection byproduct (DBP) precursors, trihalomethane (THM) formation potential (FP), and THMs in two Arizona surface waters. Limited photocatalysis (/m³) achieved reductions in most of the DBP precursor parameters (e.g., DOC, UV₂₅₄, and bromide) but led to increased chlorine demand and THMFP. In contrast, enhanced coagulation achieved reductions in the DBP precursors and THMFP. Extended photocatalysis (/m³) decreased THMFP once the energy consumption exceeded 20 kWh/m³. The photocatalytic energy requirements for THM destruction were considerably lower (EEO = …

Effectiveness Of Temporary Traffic Control Measures In Highway Work Zones, Yingfeng Li, Yong Bai

Civil and Environmental Engineering Faculty Research and Publications

In the United States, hundreds of people lose their lives each year and many more are injured due to vehicle crashes in the work zones. Over the years, temporary traffic control (TCC) measures have been developed and deployed in work zones. To continuously improve the safety, there is a need to identify the traffic control deficiencies in work zones by evaluating the effectiveness of existing TTC measures based on the real crash cases. In this study, researchers evaluated the effectiveness of several commonly used TTC methods using logistic regression techniques and various significance test methods including likelihood ratio test, score …

Short-Term Osteoclastic Activity Induced By Locally High Concentrations Of Recombinant Human Bone Morphogenetic Protein–2 In A Cancellous Bone Environment, Jeffrey M. Toth, Scott D. Boden, J. Kenneth Burkus, Jeffrey Badura, Steve M. Peckham, William Mckay

Biomedical Engineering Faculty Research and Publications

Study Design. An experimental study investigating osteoclastic activity induced by rhBMP-2 in sheep.

Objective. To examine the effects of increasing local rhBMP-2 concentration on osteoclastic response and peri-implant bone resorption.

Summary of Background Data. Level I clinical studies have established the safe and effective volume and concentration of rhBMP-2 delivered on an absorbable collagen sponge. However, peri-implant bone resorption appearing as decreased mineral density has been observed radiographically in rare instances after implantation of rhBMP-2 on an absorbable collagen sponge (rhBMP-2/ACS).

Methods. Bilateral corticocancellous defects were created in the distal femora of 30 adult sheep. Combinations of rhBMP-2/ACS implant volume …

Simulated Scatter Performance Of An Inverse-Geometry Dedicated Breast Ct System, Reema Bhagtani, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

The purpose of this work was to quantify the effects of scatter for inverse-geometry dedicated breast CT compared to cone-beam breast CT through simulations. The inverse geometry was previously proposed as an alternative to cone-beam acquisition for volumetric CT. The inverse geometry consists of a large-area scanned-source opposite a detector array that is smaller in the transverse direction. While the gantry rotates, the x-ray beam is rapidly sequenced through an array of positions, acquiring a truncated projection image at each position. Inverse-geometry CT (IGCT) is expected to detect less scatter than cone-beam methods because only a fraction of the object …

Imaging Radiation Pneumonitis In A Rat Model Of A Radiological Terrorism Incident, Robert C. Molthen, Qingping Wu, Gary S. Krenz, Meetha Medhora, Elizabeth R. Jacobs, John E. Moulder

Biomedical Engineering Faculty Research and Publications

We have developed a rat model of single, sub-lethal thoracic irradiation. Our irradiation protocol is considered representative of exposures near the detonation site of a dirty bomb or small nuclear device. The model is being used to investigate techniques for identifying, triaging and treating possible victims. In addition to physiological markers of right ventricular hypertrophy, pulmonary vascular resistance, and arterial distensibility, we present two methods for quantifying microvascular density. We used methods including microfocal X-ray imaging to investigate changes in lung structure/function resulting from radiation exposure. Radiation pneumonitis is a complication in subjects receiving thoracic irradiation. A radiographic hallmark of …

An Interactive Visual Approach To Construction Project Scheduling, Anamika Sharma

Master's Theses (2009 -)

Sound project management is an important pillar of success for a construction company. Project schedules are the primary tools for communicating the thinking and planning by the management team to all the stakeholders in a construction project. Traditional project scheduling software have become an indispensable tool for managers in various project oriented industries for tracking the schedule, the budget and resource requirements of a project as well as for preparing reports, providing on-line access to project information and communication with the members of the project team. However, these benefits are realized only after the project information is entered into the …

Rfid Tags / Planar Inductors As Chemical Sensor Platforms In Liquid Sensing Applications, Gregory Donald Schumacher-Novak

Master's Theses (2009 -)

In this work, RFID tags are investigated as a liquid-phase chemical sensing platform. A dual-layer of selective coating film with polyaniline (PANi) on top of poly(epichlorohydrin) (PECH) is used for the detection of trace amounts of organic compounds (toluene and ethylbenzene) in aqueous solutions. Various experiments were performed to evaluate the coated RFID tag sensors. Shifts in the impedance and resonant frequency due to analyte sorption are measured. Details of the responses of the dual-layer film to different pH baseline solutions are shown. The results show that this dual-layer film can be used to detect toluene and ethylbenzene with high …

The Aerodynamics Of The Knuckleball Pitch: An Experimental Investigation Into The Effects That The Seam And Slow Rotation Have On A Baseball, Michael Patrick Morrissey

Master's Theses (2009 -)

There has been plenty of research on the fluid dynamic effects on different spheres, including sports balls, such as baseballs. Baseball pitches have different velocities, rotation rates and orientations which will cause the baseball to move in different directions. There has also been plenty of research on the aerodynamics of curveballs, but not nearly as much on knuckleballs. The difference between the two is that the knuckleball has a much slower rotation rate and a different initial orientation. This causes the baseball to "knuckle," or moving erratically. This pitch in baseball is one of the hardest to pitch, hit, catch, …

Numerical Modeling Of Hemodynamics In The Thoracic Aorta And Alterations By Dacron Patch Treatment Of Aortic Coarctation, Ronak Jashwant Dholakia

Master's Theses (2009 -)

Coarctation of the aorta (CoA) is a major congenital heart disease, characterized by a severe stenosis of the proximal descending thoracic aorta. Traditionally, surgery has been the treatment of choice for CoA. Dacron patch aortoplasty gained increased popularity after its introduction in the mid-twentieth century due to its advantages over other surgical treatment methods available at the time. A major complication with Dacron patch aortoplasty has been the formation of late aneurysm with as much as 51% incidence reported in follow up studies. The change in aortic morphology and formation of aneurysms after Dacron patch surgery could lead to local …

Deflection Of A Viscoelastic Cantilever Under A Uniform Surface Stress: Applications To Static-Mode Microcantilever Sensors Undergoing Adsorption, Michael J. Wenzel, Fabien Josse, Stephen M. Heinrich

Civil and Environmental Engineering Faculty Research and Publications

The equation governing the curvature of a viscoelastic microcantilever beam loaded with a uniform surface stress is derived. The present model is applicable to static-mode microcantilever sensors made with a rigid polymer, such as SU-8. An analytical solution to the differential equation governing the curvature is given for a specific surface stress representing adsorption of analyte onto the viscoelastic beam’s surface. The solution for the bending of the microcantilever shows that, in many cases, the use of Stoney’s equation to analyze stress-induced deflection of viscoelastic microcantilevers (in the present case due to surface analyte adsorption) can lead to poor predictions …

Reconfigurable End Effector Allowing For In-Hand Manipulation Without Finger Gaiting Or Regrasping, Jacob Ames Ziesmer

Master's Theses (2009 -)

The goal of this thesis is to move a step towards the solution of the bin picking problem. A novel metamorphic end effector is proposed, tested for proof of concept and analyzed using standard techniques of degrees of freedom and graph theory as well as a classical dynamic analysis. Once proof of concept was achieved, the results from the analysis were formed into an optimization program with the hope of finding a more stable, predictable mechanism.

Development Of A Velocity Metric For Rigid-Body Planar Motion, Luis Ernesto Criales Escobar

Master's Theses (2009 -)

Two motions of motion quality have been developed for planar motion. They are the "best motion measure" and the "velocity metric". The "best motion measure" identifies the best motion for a given displacement. The "velocity metric" quantifies the discrepancy between two planar motions for the same rigid body.

The best motion measure compares the motion of each particle on the body to an "ideal", but usually unobtainable, motion. This ideal motion moves each particle from its current position to its desired position on a straight-line path. Although the ideal motion is not a valid rigid body motion, this does not …

Mesoscale Behavior Of An Aluminum-Manganese Dioxide-Epoxy Mixture Under Shock Loading: From Milli To Nano-Sized Aluminum Particles, Andrew Fraser

Master's Theses (2009 -)

The main focus of this thesis is to explore the dynamic shock compaction of multiple component mixtures, specifically Al-MnO₂-Epoxy. This will be facilitated by initially simulating the bulk dynamic response in a mesoscale configuration and then comparing these results to experimental data. The mesoscale simulations were performed in the shock code CTH. The first section will discuss the matching of experimental data to computational results. With the goal of determining the bulk shock Hugoniot, a one-dimensional flyer plate configuration was created while using a grain-geometry imported from an scanning electron microscope (SEM) micrograph of the mixture. Both the …

Capillary Perfusion Kinematics In Lungs Of Oxygen-Tolerant Rats, Madhavi Ramakrishna

Master's Theses (2009 -)

Motivation:

Prolonged exposure to oxygen at high concentrations (hyperoxia), a common treatment for hypoxemia, is toxic to the lungs. Rats exposed to 85% O₂ for 5-7 days develop tolerance to the otherwise lethal effects of 100% O₂. Elucidating the factors that contribute to this tolerance could further our understanding of the mechanisms of lung O₂ toxicity. Since vascular remodeling involving loss of capillary volume and endothelial surface area has been reported in lungs from rats exposed to 85% O₂ for 7 days, we were interested in evaluating the effect of this hyperoxia model on lung …

Eeg During Pedaling: Brain Activity During A Locomotion-Like Task In Humans, Sanket G. Jain

Master's Theses (2009 -)

This study characterized the brain electrical activity during pedaling, a locomotor-like task, in humans. We postulated that phasic brain activity would be associated with active pedaling, consistent with a cortical role in locomotor tasks. 64 channels of electroencephalogram (EEG) and 10 channels of electromyogram (EMG) data were recorded from 10 neurologically-intact volunteers while they performed active and passive (no effort) pedaling on a custom-designed stationary bicycle. Ensemble average waveforms, two dimensional topographic maps and amplitude of the beta (13-35 Hz) frequency band were analyzed and compared between active and passive trials. The absolute amplitude (peak positive-peak negative) of the EEG …

Characterization Of The Electromagnetic Fields Inside A Wire Mesh Cage For Biotelemetry, Johnny Bernard Lienau

Master's Theses (2009 -)

A wire mesh cage composed of thin conductive wires will influence the behavior of electromagnetic fields within it. Theory suggests that the cage will behave like a low Q cavity. Many researchers have investigated electromagnetic field behavior in solid walled cavities and waveguides, but little of this work has probed into the effects of a wire mesh. Additionally, few studies have investigated RF communication in these types of environments. The primary goal of this work is to research wireless communication inside a low Q wire mesh cavity in the 200-700 MHz range. Through simulated and experimental results, ideal antenna locations …

The Effect Of Office Chair Backrest Design On The Body's Metabolic Response To Office Work, Stephen H. Freier

Master's Theses (2009 -)

Most office chairs have a backrest that is wider at the shoulders than at the hips. Recently, a new office chair was developed that has a backrest that is narrower at the shoulders and wider at the hips (upwardly tapered backrest). The upwardly tapered backrest should allow users to increase their ventilatory efficiency, compared to a conventional, wide backrest. This new backrest design will hypothetically allow a user to retract their scapulae, increase expansion of the chest cavity, thus allowing the lungs more space to expand. Specific measures of improved ventilatory efficiency are an increase in tidal volume (V_{t …}