Engineering Commons^™

Reducing Orbit Covariance For Continuous Thrust Spacecraft Transfers, Scott Zimmer, Oscar Ocampo, Robert H. Bishop

Mechanical Engineering Faculty Research and Publications

The calculus of variations is used to develop the necessary theory and derive the optimality conditions for a spacecraft to transfer between a set of initial and final conditions, while minimizing a combination of fuel consumption and a function of the estimation error covariance matrix associated with the spacecraft state. The theory is developed in a general manner that allows for multiple observers, moving observers, covariance associated with an arbitrary frame, a wide variety of observation types, multiple gravity bodies, and uncertainties in the spacecraft equations of motion based on the thrusting status of the engine. A series of example …

Concrete Cracking In New Bridge Decks And Overlays, Baolin Wan, Christopher Foley, Jordan Komp

Transportation Reports with the Wisconsin Department of Transportation

There appears to be a trend for new bridge decks in the state of Wisconsin to develop early-age transverse cracks and map cracks on concrete overlays. A comprehensive literature review of the potential causes of concrete bridge deck cracking is provided. Fifteen bridge structures found in the recently completed Marquette Interchange were analyzed using 21 variables thought to cause early-age bridge deck cracking. Visual inspection of sixteen bridges in Milwaukee is described. The inspections show that the continuous superstructures have more cracks than the simply-supported bridges. A finite element model was created for a typical two-span continuous superstructure with HL-93 …

Ct Energy Weighting In The Presence Of Scatter And Limited Energy Resolution, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose: Energy-resolved CT has the potential to improve the contrast-to-noise ratio(CNR) through optimal weighting of photonsdetected in energy bins. In general, optimal weighting gives higher weight to the lower energy photons that contain the most contrast information. However, low-energy photons are generally most corrupted by scatter and spectrum tailing, an effect caused by the limited energy resolution of the detector. This article first quantifies the effects of spectrum tailing on energy-resolved data, which may also be beneficial for material decomposition applications. Subsequently, the combined effects of energy weighting, spectrum tailing, and scatter are investigated through simulations.

Methods: The study first …

Shift Estimation Algorithm For Dynamic Sensors With Frame-To-Frame Variation In Their Spectral Response, Todd M. Giles, Majeed M. Hayat, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

This study is motivated by the emergence of a new class of tunable infrared spectral-imaging sensors that offer the ability to dynamically vary the sensor's intrinsic spectral response from frame to frame in an electronically controlled fashion. A manifestation of this is when a sequence of dissimilar spectral responses is periodically realized, whereby in every period of acquired imagery, each frame is associated with a distinct spectral band. Traditional scene-based global shift estimation algorithms are not applicable to such spectrally heterogeneous video sequences, as a pixel value may change from frame to frame as a result of both global motion …

Mitochondrial Matrix K+ Flux Independent Of Large-Conductance Ca2+-Activated K+ Channel Opening, Mohammed Aldakkak, David F. Stowe, Qunli Cheng, Wai-Meng Kwok, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

Large-conductance Ca²⁺-activated K⁺ channels (BK_Ca) in the inner mitochondrial membrane may play a role in protecting against cardiac ischemia-reperfusion injury. NS1619 (30 μM), an activator of BK_Ca channels, was shown to increase respiration and to stimulate reactive oxygen species generation in isolated cardiac mitochondria energized with succinate. Here, we tested effects of NS1619 to alter matrix K⁺, H⁺, and swelling in mitochondria isolated from guinea pig hearts. We found that 30 μM NS1619 did not change matrix K⁺, H⁺, and swelling, but that 50 and 100 …

Editorial Special Issue On Enhancement Algorithms, Methodologies And Technology For Spectral Sensing, James O. Jensen, Robert J. Trew, Dwight L. Woolard, Neelam Gupta, Jean-Marc Theriault, Majeed M. Hayat, Yanqiu Li, Patti Gillespie

Electrical and Computer Engineering Faculty Research and Publications

The paper is an editorial issue on enhancement algorithms, methodologies and technology for spectral sensing and serves as a valuable and useful reference for researchers and technologists interested in the evolving state-of-the-art and/or the emerging science and technology base associated with spectral-based sensing and monitoring problem. This issue is particularly relevant to those seeking new and improved solutions for detecting chemical, biological, radiological and explosive threats on the land, sea, and in the air.

The Effect Of Ace Inhibition On The Pulmonary Vasculature In Combined Models Of Chronic Hypoxia And Pulmonary Arterial Banding In Sprague Dawley Rats, Shanelle Clarke, Shelley Baumgardt, Robert C. Molthen

Biomedical Engineering Faculty Research and Publications

Microfocal CT was used to image the pulmonary arterial (PA) tree in rodent models of pulmonary hypertension (PH). CT images were used to measure the arterial tree diameter along the main arterial trunk at several hydrostatic intravascular pressures and calculate distensibility. High-resolution planar angiographic imaging was also used to examine distal PA microstructure. Data on pulmonary artery tree morphology improves our understanding of vascular remodeling and response to treatments. Angiotensin II (ATII) has been identified as a mediator of vasoconstriction and proliferative mitotic function. ATII has been shown to promote vascular smooth muscle cell hypertrophy and hyperplasia as well as …

Analyzing Motorists’ Responses To Temporary Signage In Highway Work Zones, Yong Bai, Kris Finger, Yue Li

Civil and Environmental Engineering Faculty Research and Publications

For decades, the importance of highway work zone safety has increased considerably with the continual increase in the number of highway work zones present on highways for repairs and expansion. Rural work zones on two-lane highways are particularly hazardous and cause a significant safety concern due to the disruption of regular traffic flow. In this study, researchers determined motorists’ responses to warning signs in rural, two-lane highway work zones. The researchers divided vehicles into three classes (passenger car, truck, and semitrailer) and compared the mean change in speed of these classes based on three different sign setups: portable changeable message …

Time-Efficient Patient-Specific Quantification Of Regional Carotid Artery Fluid Dynamics And Spatial Correlation With Plaque Burden, John F. Ladisa, Mark Bowers, Leanne Harmann, Robert W. Prost, Anil Vamsi Doppalapudi, Tayyab Mohyuddin, Osama Zaidat, Raymond Q. Migrino

Biomedical Engineering Faculty Research and Publications

Purpose:

Low wall shear stress (WSS) and high oscillatory shear index (OSI) influence plaque formation, yet little is known about their role in progression/regression of established plaques because of lack of practical means to calculate them in individual patients. Our aim was to use computational fluid dynamics(CFD) models of patients with carotid plaque undergoing statin treatment to calculate WSS and OSI in a time-efficient manner, and determine their relationship to plaque thickness (PT), plaque composition (PC), and regression.

Methods:

Eight patients (68±9 yr, one female) underwent multicontrast 3 T MRI at baseline and six-month post statin treatment. PT and PC …

Acoustic Censusing Using Automatic Vocalization Classification And Identity Recognition, Kuntoro Adi, Michael T. Johnson, Tomasz S. Osiejuk

Electrical and Computer Engineering Faculty Research and Publications

This paper presents an advanced method to acoustically assess animal abundance. The framework combines supervised classification (song-type and individual identity recognition), unsupervised classification (individual identity clustering), and the mark-recapture model of abundance estimation. The underlying algorithm is based on clustering using hidden Markovmodels (HMMs) and Gaussian mixture models (GMMs) similar to methods used in the speech recognition community for tasks such as speaker identification and clustering. Initial experiments using a Norwegian ortolan bunting (Emberiza hortulana) data set show the feasibility and effectiveness of the approach. Individually distinct acoustic features have been observed in a wide range of animal …

Effects Of Hydrogen Pretreatment On Physical-Vapor-Deposited Nickel Catalyst For Multi-Walled Carbon Nanotube Growth, Benjamin L. Crossley, Mauricio Kossler, Ronald A. Coutu Jr., Lavern A. Starman, Peter J. Collins

Electrical and Computer Engineering Faculty Research and Publications

Physical vapor deposited nickel catalyst layers of 10, 50, 100, 200, 350, and 500 angstroms were granulated using hydrogen plasma for varying times to determine an effective carbon nanotube (CNT) growth process using microwave plasma enhanced CVD (MPECVD). Nickel was deposited via sputtering or evaporation. The catalyst granule size, density, and resulting CNTs were analyzed. Sputtered nickel of 50 angstroms with 5 minutes of hydrogen plasma pretreatment resulted in the most effective CNT growth.

Tapping Environmental History To Recreate America’S Colonial Hydrology, Christopher L. Pastore, Mark B. Green, Daniel J. Bain, Andrea Muñoz-Hernandez, Charles J. Vörösmarty, Jennifer Arrigo, Sara Brandt, Jonathan M. Duncan, Francesca Greco, Hyojin Kim, Sanjiv Kumar, Michael Lally, Anthony J. Parolari, Brian Pellerin, Nira Salant, Adam Schlosser, Kate Zalzal

Civil and Environmental Engineering Faculty Research and Publications

To properly remediate, improve, or predict how hydrological systems behave, it is vital to establish their histories. However, modern-style records, assembled from instrumental data and remote sensing platforms, hardly exist back more than a few decades. As centuries of data is preferable given multidecadal fluxes of both meteorology/climatology and demographics, building such a history requires resources traditionally considered only useful in the social sciences and humanities. In this Feature, Pastore et al. discuss how they have undertaken the synthesis of historical records and modern techniques to understand the hydrology of the Northeastern U.S. from Colonial times to modern day. Such …

Unconventional Uses Of Cantilevers For Chemical Sensing In Gas And Liquid Environments, Isabelle Dufour, Fabien Josse, Stephen M. Heinrich, C. Lucat, C. Ayela, F. Ménil, Oliver Brand

Civil and Environmental Engineering Faculty Research and Publications

Microcantilevers used as (bio)chemical sensors are usually coated with a chemically sensitive layer. The coated devices operate either in a static bending regime or in a dynamic flexural mode. While the coated devices operate generally well in both the static and dynamic mode, they do suffer from certain shortcomings depending on the medium of operation and the application, including lack of selectivity and of reversibility of the sensitive coating and a reduced quality factor due to the surrounding medium. In particular, the performance of microcantilevers excited in their standard out-of-plane dynamic mode drastically decreases in viscous liquid media. Moreover, the …

The Effect Of Abductor Muscle And Anterior-Posterior Hip Contact Load Simulation On The In-Vitro Primary Stability Of A Cementless Hip Stem, Youngbae Park, Carolyne Albert, Yong-San Yoon, Göran Fernlund, Hanspeter Frei, Thomas R. Oxland

Biomedical Engineering Faculty Research and Publications

Background

In-vitro mechanical tests are commonly performed to assess pre-clinically the effect of implant design on the stability of hip endoprostheses. There is no standard protocol for these tests, and the forces applied vary between studies. This study examines the effect of the abductor force with and without application of the anterior-posterior hip contact force in the in-vitro assessment of cementless hip implant stability.

Methods

Cementless stems (VerSys Fiber Metal) were implanted in twelve composite femurs which were divided into two groups: group 1 (N = 6) was loaded with the hip contact force only, whereas group 2 (N = …

Integration Mechanisms For Heading Perception, Elif M. Sikoglu, Finnegan J. Calabro, Scott A. Beardsley, Lucia M. Vaina

Biomedical Engineering Faculty Research and Publications

Previous studies of heading perception suggest that human observers employ spatiotemporal pooling to accommodate noise in optic flow stimuli. Here, we investigated how spatial and temporal integration mechanisms are used for judgments of heading through a psychophysical experiment involving three different types of noise. Furthermore, we developed two ideal observer models to study the components of the spatial information used by observers when performing the heading task. In the psychophysical experiment, we applied three types of direction noise to optic flow stimuli to differentiate the involvement of spatial and temporal integration mechanisms. The results indicate that temporal integration mechanisms play …

Motion Of The Multisegmental Foot In Hallux Valgus, Karl Canseco, Leah Rankine, Jason T. Long, Thomas Smedberg, Richard Marks, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Hallux valgus is a common condition characterized by lateral deviation of the large toe and medial deviation of the first metatarsal. While some gait analyses of patients with hallux valgus have been performed using plantar pressures, very little is known about the kinematics of gait in this population. The purpose of this study was to evaluate triplanar kinematics in patients with hallux valgus using a multisegmental foot model. Materials and Methods: A 15-camera Vicon Motion Analysis System was used to evaluate the gait of 38 feet in 33 patients with mild to severe hallux valgus. The Milwaukee foot model was …

Measurement And Modeling Of Infrared Nonlinear Absorption Coefficients And Laser-Induced Damage Thresholds In Ge And Gasb, T. J. Wagner, M. A. Bohn, Ronald A. Coutu Jr., L. P. Gonzalez, J. M. Murray, K. L. Schepler, S. Guha

Electrical and Computer Engineering Faculty Research and Publications

Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 μm for the first time, to our knowledge. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 μm and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al₂O₃ anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for picosecond or nanosecond …

Information Theoretic Approach For Assessing Image Fidelity In Photon-Counting Arrays, Srikanth R. Narravula, Majeed M. Hayat, Bahram Javidi

Electrical and Computer Engineering Faculty Research and Publications

The method of photon-counting integral imaging has been introduced recently for three-dimensional object sensing, visualization, recognition and classification of scenes under photon-starved conditions. This paper presents an information-theoretic model for the photon-counting imaging (PCI) method, thereby providing a rigorous foundation for the merits of PCI in terms of image fidelity. This, in turn, can facilitate our understanding of the demonstrated success of photon-counting integral imaging in compressive imaging and classification. The mutual information between the source and photon-counted images is derived in a Markov random field setting and normalized by the source-image’s entropy, yielding a fidelity metric that is between …

A Fast Nir Spectrometer For Examining Explosive Events: Emission Of Petn Based Explosives And H2O Absorption Method Feasibility, Scott Piecuch

Master's Theses (2009 -)

The chemical dynamics and decomposition pathways of explosive materials are not entirely known. Measurements of chemical transients during explosive events can lead to enhanced knowledge of the detailed chemistry and eventually control of the end products; however, these measurements are often difficult to obtain due to fast time scales and harsh environments. Optical diagnostics present fast-response, minimally invasive methods for resolving properties in detonation environments and previous fast spectroscopic measurements have been recorded in the ultra-violet and visible regions. This work extends the range of such measurements to the near-infrared (NIR) through the development of a fiber-coupled NIR spectrometer utilizing …

Demonstration Of A Bias Tunable Quantum Dots-In-A-Well Focal Plane Array, Jonathan Andrews, Woo-Yong Jang, Jorge E. Pezoa, Yagya D. Sharma, Sang Jun Lee, Sam Kyu Noh, Majeed M. Hayat, Sergio Restaino, Scott W. Teare, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

Infrared detectors based on quantum wells and quantum dots have attracted a lot of attention in the past few years. Our previous research has reported on the development of the first generation of quantum dots-in-a-well (DWELL) focal plane arrays, which are based on InAs quantum dots embedded in an InGaAs well having GaAs barriers. This focal plane array has successfully generated a two-color imagery in the mid-wave infrared (i.e. 3–5 μm) and the long-wave infrared (i.e. 8–12 μm) at a fixed bias voltage. Recently, the DWELL device has been further modified by embedding InAs quantum dots in InGaAs …

On Coupling A Lumped Parameter Heart Model And A Three-Dimensional Finite Element Aorta Model, H. J. Kim, Irene E. Vignon-Clementel, C. A. Figueroa, John F. Ladisa, K. E. Jansen, Jeffrey A. Feinstein, Charles A. Taylor

Biomedical Engineering Faculty Research and Publications

Aortic flow and pressure result from the interactions between the heart and arterial system. In this work, we considered these interactions by utilizing a lumped parameter heart model as an inflow boundary condition for three-dimensional finite element simulations of aortic blood flow and vessel wall dynamics. The ventricular pressure–volume behavior of the lumped parameter heart model is approximated using a time varying elastance function scaled from a normalized elastance function. When the aortic valve is open, the coupled multidomain method is used to strongly couple the lumped parameter heart model and three-dimensional arterial models and compute ventricular volume, ventricular pressure, …

Comparison Of Cumulative Planimetry Versus Manual Dissection To Assess Experimental Infarct Size In Isolated Hearts, Matthias L. Riess, Samhita S. Rhodes, David F. Stowe, Mohammed Aldakkak, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

Introduction

Infarct size (IS) is an important variable to estimate cardiac ischemia/reperfusion injury in animal models. Triphenyltetrazolium chloride (TTC) stains viable cells red while leaving infarcted cells unstained. To quantify IS, infarcted and non-infarcted tissue is often manually dissected and weighed (IS-DW). An alternative is to measure infarcted areas by cumulative planimetry (IS-CP).

Methods

We prospectively compared these two methods in 141 Langendorff-prepared guinea pig hearts (1.44 ± 0.02 g) that were part of different studies on mechanisms of cardioprotection. Hearts were perfused with Krebs–Ringer's and subjected to 30 min global ischemia after various cardioprotective treatments. Two hours after reperfusion …

Exploiting Multiple Sensory Modalities In Brain-Machine Interfaces, Aaron J. Suminski, Dennis C. Tkach, Nicholas G. Hatsopoulos

Biomedical Engineering Faculty Research and Publications

Recent improvements in cortically-controlled brain-machine interfaces (BMIs) have raised hopes that such technologies may improve the quality of life of severely motor-disabled patients. However, current generation BMIs do not perform up to their potential due to the neglect of the full range of sensory feedback in their strategies for training and control. Here we confirm that neurons in the primary motor cortex (MI) encode sensory information and demonstrate a significant heterogeneity in their responses with respect to the type of sensory modality available to the subject about a reaching task. We further show using mutual information and directional tuning analyses …

A Framework For Bioacoustic Vocalization Analysis Using Hidden Markov Models, Yao Ren, Michael T. Johnson, Patrick J. Clemins, Michael Darre, Sharon Stuart Glaeser, Tomasz S. Osiejuk, Ebenezer Out-Nyarko

Electrical and Computer Engineering Faculty Research and Publications

Using Hidden Markov Models (HMMs) as a recognition framework for automatic classification of animal vocalizations has a number of benefits, including the ability to handle duration variability through nonlinear time alignment, the ability to incorporate complex language or recognition constraints, and easy extendibility to continuous recognition and detection domains. In this work, we apply HMMs to several different species and bioacoustic tasks using generalized spectral features that can be easily adjusted across species and HMM network topologies suited to each task. This experimental work includes a simple call type classification task using one HMM per vocalization for repertoire analysis of …

Analysis And Diagnostics Of Adjacent And Nonadjacent Broken-Rotor-Bar Faults In Squirrel-Cage Induction Machines, Gennadi Y. Sizov, Ahmed Mohamed Sayed Ahmed, Chia-Chou Yeh, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

In this paper, faults associated with the rotor of an induction machine are considered. More specifically, effects of adjacent and nonadjacent bar breakages on rotor fault diagnostics in squirrel-cage induction machines are studied. It is shown that some nonadjacent bar breakages may result in the masking of the commonly used fault indices and, hence, may lead to a possible misdiagnosis of the machine. A discussion of the possible scenarios of these breakages as well as some conclusions regarding the types of squirrel-cage induction machines (number of poles, number of squirrel-cage bars, etc.) that may be more prone to these nonadjacent …

Highway Work Zone Risk Factors And Their Impact On Crash Severity, Yingfeng Li, Yong Bai

Civil and Environmental Engineering Faculty Research and Publications

Numerous factors may contribute to high-severity crashes in highway work zones. Identifying these factors and then alleviating their impact is a challenging task that traffic engineers and researchers have to confront. In this study, the work zone risk factors that could increase the probability of causing fatalities when severe crashes occur were examined using a comprehensive approach. The researchers first identified the significant risk factors based on a screening process that incorporates both statistical analyses and empirical research findings. They then systematically investigated these factors using logistic regression and frequency analysis techniques. The severe crashes including the fatal crashes between …

Modulation Of Mitochondrial Bioenergetics In The Isolated Guinea Pig Beating Heart By Potassium And Lidocaine Cardioplegia: Implications For Cardioprotection, Mohammed Aldakkak, David F. Stowe, Edward J. Lesnefsky, James S. Heisner, Qun Chen, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

Mitochondria are damaged by cardiac ischemia/reperfusion (I/R) injury but can contribute to cardioprotection. We tested if hyperkalemic cardioplegia (CP) and lidocaine (LID) differently modulate mitochondrial (m) bioenergetics and protect hearts against I/R injury. Guinea pig hearts (n = 71) were perfused with Krebs Ringer's solution before perfusion for 1 minute just before ischemia with either CP (16 mM K+) or LID (1 mM) or Krebs Ringer's (control, 4 mM K+). The 1-minute perfusion period assured treatment during ischemia but not on reperfusion. Cardiac function, NADH, FAD, m[Ca2+], and superoxide (reactive oxygen species) were assessed at baseline, during the 1-minute perfusion, …

Flexor Reflex Decreases During Sympathetic Stimulation In Chronic Human Spinal Cord Injury, Mark Kevin Garrison, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

A better understanding of autonomic influence on motor reflex pathways in spinal cord injury is important to the clinical management of autonomic dysreflexia and spasticity in spinal cord injured patients. The purpose of this study was to examine the modulation of flexor reflex windup during episodes of induced sympathetic activity in chronic human spinal cord injury (SCI). We simultaneously measured peripheral vascular conductance and the windup of the flexor reflex in response to conditioning stimuli of electrocutaneous stimulation to the opposite leg and bladder percussion. Flexor reflexes were quantified using torque measurements of the response to a noxious electrical stimulus …

Splenic Trauma As An Adverse Effect Of Torso-Protecting Side Airbags: Biomechanical And Case Evidence, Jason John Hallman, Karen J. Brasel, Narayan Yoganandan, Frank A. Pintar

Biomedical Engineering Faculty Research and Publications

Injury mechanisms from frontal airbags, first identified in anecdotal reports, are now well documented for pediatric, small female, and out-of-position occupants. In contrast, torso side airbags have not yet been consistently associated with specific injury risks in field assessments. To determine possible torso side airbag-related injuries, the present study identified crashes involving side airbags from reports within the CIREN, NASS, and SCI databases. Injury patterns were compared to patterns from lateral crashes in absence of side airbag. Splenic trauma (AIS 3+) was found present in five cases of torso side airbag deployment at lower impact severity (as measured by velocity …

Bit Error Rates For Ultrafast Apd Based Optical Receivers: Exact And Large Deviation Based Asymptotic Approaches, Peng Sun, Majeed M. Hayat, Abhik K. Das

Electrical and Computer Engineering Faculty Research and Publications

Exact analysis as well as asymptotic analysis, based on large-deviation theory (LDT), are developed to compute the bit-error rate (BER) for ultrafast avalanche-photodiode (APD) based optical receivers assuming on-off keying and direct detection. The effects of intersymbol interference (ISI), resulting from the APD's stochastic avalanche buildup time, as well as the APD's dead space are both included in the analysis. ISI becomes a limiting factor as the transmission rate approaches the detector's bandwidth, in which case the bit duration becomes comparable to APD's avalanche buildup time. Further, the effect of dead space becomes significant in high-speed APDs that employ thin …