Engineering Commons^™

Quantitative Models Of The Rat Pulmonary Arterial Tree Morphometry Applied To Hypoxia-Induced Arterial Remodeling, Robert C. Molthen, Kelly L. Karau, Christopher A. Dawson

Biomedical Engineering Faculty Research and Publications

Little is known about the constituent hemodynamic consequences of structural changes that occur in the pulmonary arteries during the onset and progression of pulmonary arterial remodeling. Many disease processes are known to be responsible for vascular remodeling that leads to pulmonary arterial hypertension, cor pulmonale, and death. Histology has been the primary tool for evaluating pulmonary remodeling, but it does not provide information on intact vascular structure or the vessel mechanical properties. This study is an extension of our previous work in which we developed an alternative imaging technique to evaluate pulmonary arterial structure. The lungs from Sprague-Dawley rats were …

Measurement Of Handle Forces For Crimping Connectors And Cutting Cable In The Electric Power Industry, Richard W. Marklin, Lia Lazuardi, Jeremy R. Wilzbacher

Mechanical Engineering Faculty Research and Publications

Overhead and underground line work in the electric power industry is physically very strenuous and can expose workers to musculoskeletal disorders (MSDs), particularly in the upper extremity. Crimping compression connectors—such as sleeve connectors and lugs—and cutting cables are two of the most frequent tasks that line workers perform. Line workers at many utilities in the US crimp connectors and cut cable with long-handled manual tools. However, the actual magnitude of the forces applied to the handles of these tools is not known. The objectives of this laboratory study were to measure the forces applied to the handles of a manual …

Condition Monitoring Of Squirrel-Cage Induction Motors Fed By Pwm-Based Drives Using A Parameter Estimation Approach, Behrooz Mirafzal, F. Fateh, Chia-Chou Yeh, Richard J. Povinelli, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

Abstract:

A rotor condition monitoring technique is presented in this paper based on a parameter estimation approach. In this technique, the stator currents, voltages and motor speed are used as the input signals, where the outputs will be the rotor's inductance, resistance and consequently rotor time constant. This approach is verified by simulation of two different induction motor cases. These simulations are buttressed by experimental data obtained for a 2-hp induction motor in the case of healthy as well as one, three and five rotor bar breakages. In these tests, the induction motor was energized from a PWM-based drive, in …

Admittance Selection For Force-Guided Assembly Of Polygonal Parts Despite Friction, Shuguang Huang, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

An important issue in the development of force guidance assembly strategies is the specification of an appropriate admittance control law. This paper identifies conditions to be satisfied when selecting the appropriate admittance to achieve force-guided assembly of polygonal parts for multipoint contact with friction. These conditions restrict the admittance behavior for each of the various one-point and two-point contact cases and ensure that the motion that results from contact reduces part misalignment for each case. We show that, for bounded friction and part misalignments, if the identified conditions are satisfied for a finite number of contact configurations and friction coefficients, …

Micro-Switches With Sputtered Au, Aupd, Au-On-Aupt, And Auptcu Alloy Electric Contacts, Ronald A. Coutu Jr., P. E. Kladitis, R. Cortez, R. E. Strawser, Robert L. Crane

Electrical and Computer Engineering Faculty Research and Publications

This work is the first to report on a new analytic model for predicting micro-contact resistance and the design, fabrication, and testing of microelectromechanical systems (MEMS) metal contact switches with sputtered bi-metallic (i.e. gold (Au)-on-Au-platinum (Pt), (Au-on-Au-(6%)Pt)), binary alloy (i.e. Au-palladium (Pd), (Au-(2%)Pd)), and tertiary alloy (i.e. Au-Pt-copper (Cu), (Au-(5%)Pt-(0.5%)Cu)) electric contacts. The micro-switches with bi-metallic and binary alloy contacts resulted in contact resistance between 1-2 /spl Omega/ and, when compared to micro-switches with sputtered Au electric contacts, exhibited a 3.3 and 2.6 times increase in switching lifetime, respectively. The tertiary alloy exhibited a 6.5 times increase in switch lifetime …

A Comparison Of Micro-Switch Analytic, Finite Element, And Experimental Results, Ronald A. Coutu Jr., P. E. Kladitis, Lavern A. Starman, J. R. Reid

Electrical and Computer Engineering Faculty Research and Publications

Electrostatically actuated, metal contact, micro-switches depend on having adequate contact force to achieve desired, low contact resistance. In this study, higher contact forces resulted from overdriving cantilever beam style switches, after pull-in or initial contact, until the beam collapsed onto the drive or actuation electrode. The difference between initial contact and beam collapse was defined as the useful contact force range. Micro-switch pull-in voltage, collapse voltage, and contact force predictions, modeled analytically and with the CoventorWare finite element software package, were compared to experimental results. Contact resistance was modeled analytically using Maxwellian spreading resistance theory. Contact resistance and contact …

Cardioprotection By Glucose-Insulin-Potassium: Dependence On KAtp Channel Opening And Blood Glucose Concentration Before Ischemia, John F. Ladisa, John G. Krolikowski, Paul S. Pagel, David C. Warltier, Judy R. Kersten

Biomedical Engineering Faculty Research and Publications

We tested the hypothesis that glucose-insulin-potassium (GIK)-induced protection against myocardial infarction depends on ATP-dependent K⁺ (K_ATP) channel activation and is abolished by hyperglycemia before the ischemia. Dogs were subjected to a 60-min coronary artery occlusion and 3-h reperfusion in the absence or presence of GIK (25% dextrose; 50 IU insulin/l; 80 mM/l KCl infused at 1.5 ml·kg⁻¹·h⁻¹) beginning 75 min before coronary artery occlusion or 5 min before reperfusion. The role of K_ATP channels was evaluated by pretreatment with glyburide (0.1 mg/kg). The efficacy of GIK was investigated with increases in blood …

Admittance Selection For Force-Guided Assembly Of Polyhedral Parts In Single-Point Contact, Shuguang Huang, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

The selection of the proper admittance is important in achieving force-guided assembly. This paper identifies procedures for selecting the appropriate spatial admittance to achieve reliable force-guided assembly of polyhedral parts for single-point frictionless contact cases. Sets of conditions that are imposed on the admittance matrix for different types of single-point contact are presented. These conditions ensure that the motion that results from contact reduces part misalignment in the selected contact state. We show that, for bounded misalignments, if an admittance satisfies the misalignment-reduction conditions at a finite number of contact configurations, then the admittance also satisfy the conditions at all …

Effect Of Ventilation Rate On Instilled Surfactant Distribution In The Pulmonary Airways Of Rats, Joseph C. Anderson, Robert C. Molthen, Christopher A. Dawson, Steven Thomas Haworth, Joseph L. Bull, Matthew R. Glucksburg, James B. Grotberg

Biomedical Engineering Faculty Research and Publications

Liquid can be instilled into the pulmonary airways during medical procedures such as surfactant replacement therapy, partial liquid ventilation, and pulmonary drug delivery. For all cases, understanding the dynamics of liquid distribution in the lung will increase the efficacy of treatment. A recently developed imaging technique for the study of real-time liquid transport dynamics in the pulmonary airways was used to investigate the effect of respiratory rate on the distribution of an instilled liquid, surfactant, in a rat lung. Twelve excised rat lungs were suspended vertically, and a single bolus (0.05 ml) of exogenous surfactant (Survanta, Ross Laboratories, Columbus, OH) …

Stent Design Properties And Deployment Ratio Influence Indexes Of Wall Shear Stress: A Three-Dimensional Computational Fluid Dynamics Investigation Within A Normal Artery, John F. Ladisa, Lars E. Olson, Ismail Guler, Douglas Anthony Hettrick, Said H. Audi, Judy R. Kersten, David C. Warltier, Paul S. Pagel

Biomedical Engineering Faculty Research and Publications

Restenosis limits the effectiveness of stents, but the mechanisms responsible for this phenomenon remain incompletely described. Stent geometry and expansion during deployment produce alterations in vascular anatomy that may adversely affect wall shear stress (WSS) and correlate with neointimal hyperplasia. These considerations have been neglected in previous computational fluid dynamics models of stent hemodynamics. Thus we tested the hypothesis that deployment diameter and stent strut properties (e.g., number, width, and thickness) influence indexes of WSS predicted with three-dimensional computational fluid dynamics. Simulations were based on canine coronary artery diameter measurements. Stent-to-artery ratios of 1.1 or 1.2:1 were modeled, and computational …

Optimal Design Of Low Order Controllers Satisfying Sensitivity And Robustness Constraint, Mark L. Nagurka, O. Yaniv

Mechanical Engineering Faculty Research and Publications

The set of all stabilizing controllers of a given low order structure that guarantee specifications on the gain margin, phase margin and a bound on the sensitivity corresponds to a region in n-dimensional space defined by the coefficients of the controllers. For several practical criteria defined in the paper it is shown that the optimal controller lies on the surface of that region. Moreover, it is shown how to reduce that region to avoid actuator saturation during operation.

Selecting Metal Alloy Electric Contact Materials For Mems Switches, Ronald A. Coutu Jr., Paul E. Kladitis, Kevin D. Leedy, Robert L. Crane

Electrical and Computer Engineering Faculty Research and Publications

This paper presents a method for selecting metal alloys as the electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This procedure consists of reviewing macro-switch lessons learned, utilizing equilibrium binary alloy phase diagrams, obtaining thin film material properties and, based on a suitable model, predicting contact resistance performance. After determining a candidate alloy material, MEMS switches were designed, fabricated and tested to validate the alloy selection methodology. Minimum average contact resistance values of 1.17 and 1.87 Ω were measured for micro-switches with gold (Au) and gold–platinum (Au–(6.3%)Pt) alloy electric contacts, respectively. In addition, 'hot-switched' life cycle test results …

Time Series Classification Using Gaussian Mixture Models Of Reconstructed Phase Spaces, Richard J. Povinelli, Michael T. Johnson, Andrew C. Lindgren, Jinjin Ye

Electrical and Computer Engineering Faculty Research and Publications

A new signal classification approach is presented that is based upon modeling the dynamics of a system as they are captured in a reconstructed phase space. The modeling is done using full covariance Gaussian mixture models of time domain signatures, in contrast with current and previous work in signal classification that is typically focused on either linear systems analysis using frequency content or simple nonlinear machine learning models such as artificial neural networks. The proposed approach has strong theoretical foundations based on dynamical systems and topological theorems, resulting in a signal reconstruction, which is asymptotically guaranteed to be a complete …

Computerized Biofeedback Knee Goniometer: Acceptance And Effect On Exercise Behavior In Post-Total Knee Arthroplasty Rehabilitation, Todd A. Kuiken, Hagay Amir, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

Objective

To assess device accuracy, patient acceptance, and effect of a computerized biofeedback knee goniometer (CBG), on patients’ compliance with active range of motion (AROM) exercises after total knee arthroplasty (TKA).

Design

Two-stage study: measurement validation on asymptomatic controls and an unblinded, multiple crossover trial.

Setting

Inpatient rehabilitation.

Participants

Asymptomatic controls (n=14) and post-TKA inpatients (n=11).

Interventions

For measurement validation, CBG-angle measurements were compared with manual, clinician-obtained angles. To assess motivational effect, the CBG was worn after TKA; on alternating days, it either monitored AROM silently (no feedback) or provided audiovisual feedback about reaching preset range of motion (ROM) goals …

Application Of Bi-State Magnetic Material To Automotive Offset-Coupled Ipm Starter/Alternator Machine, Ayman M. El-Refaie, Russell Manzke, Thomas M. Jahns

Electrical and Computer Engineering Faculty Research and Publications

This paper investigates a new approach to designing high-speed interior permanent-magnet (IPM) synchronous machines using a bi-state soft magnetic material. The bi-state material can have its normally high magnetic permeability permanently reduced in localized regions to that of air by means of heat treatment. This new work significantly expands a previous investigation by considering offset-coupled IPM machines that make it possible to significantly increase the rotor speed while retaining all of the other specifications of the 6-kW starter/alternator application. Lumped-parameter models, Monte Carlo optimization, and both electromagnetic and structural finite-element analysis are used to develop new offset-coupled IPM machine designs …

Geometry Analysis Of An Inverse-Geometry Volumetric Ct System With Multiple Detector Arrays, Samuel R. Mazin, Taly Gilat Schmidt, Edward G. Solomon, Rebecca Fahrig, Norbert J. Pelc

Biomedical Engineering Faculty Research and Publications

An inverse-geometry volumetric CT (IGCT) system for imaging in a single fast rotation without cone-beam artifacts is being developed. It employs a large scanned source array and a smaller detector array. For a single-source/single-detector implementation, the FOV is limited to a fraction of the source size. Here we explore options to increase the FOV without increasing the source size by using multiple detectors spaced apart laterally to increase the range of radial distances sampled. We also look at multiple source array systems for faster scans. To properly reconstruct the FOV, Radon space must be sufficiently covered and sampled in a …

Robust Procedures For Obtaining Assembly Contact State Extremal Configurations, Pan Feng, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

Two important components in the selection of an admittance that facilitates force-guided assembly are the identification of: 1) the set of feasible contact states, and 2) the set of configurations that span each contact state, i.e., the extremal configurations. We present a procedure to automatically generate both sets from CAD models of the assembly parts. In the procedure, all possible combinations of principle contacts are considered when generating hypothesized contact states. The feasibility of each is then evaluated in a genetic algorithm based optimization procedure. The maximum and minimum value of each of the 6 configuration variables spanning each contact …

A Vector Quantization Method For Nearest Neighbor Classifier Design, Chen-Wen Yen, Chieh-Neng Young, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

This paper proposes a nearest neighbor classifier design method based on vector quantization (VQ). By investigating the error distribution pattern of the training set, the VQ technique is applied to generate prototypes incrementally until the desired classification result is reached. Experimental results demonstrate the effectiveness of the method.

Structural Analysis Of Sign Bridge Structures And Luminaire Supports, Christopher Foley, Raymond Fournelle, Scott J. Ginal, John L. Peronto

Transportation Reports with the Wisconsin Department of Transportation

The Wisconsin Department of Transportation has experienced failures of a high-mast luminaire (HML) support structure and a full-span overhead sign support structure. Furthermore, cracking has been found in many sign support structures composed of welded round hollow structural shapes (HSS). The purpose of the research conducted was to provide fatigue life estimates for these structures, which could then shed light onto the causes of the cracking found and the failures experienced. The analytical and experimental effort conducted was also used to establish rational inspection intervals for these structures and recommend changes (as required) to the procedures for design of high-mast …

Induction Machine Broken-Bar Fault Diagnosis Using The Rotor Magnetic Field Space-Vector Orientation, Behrooz Mirafzal, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

A new technique based on rotor magnetic field space vector orientation is presented to diagnose broken-bar faults in induction machines operating at steady state. In this technique, stator currents and voltages are used as inputs to compute and subsequently observe the rotor magnetic field orientation, which has a more significant "swing-like" pendulous oscillation in case of broken-bar faults than in healthy operation. It will be shown here that the range of this "pendulous oscillation" is a function of the number of broken bars. Also in this technique, it was found that an inter-turn shorted stator-winding fault, which exhibits similar pendulous …

A False Acceptance Error Controlling Method For Hyperspherical Classifiers, Chen-Wen Yen, Chieh-Neng Young, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

Controlling false acceptance errors is of critical importance in many pattern recognition applications, including signature and speaker verification problems. Toward this goal, this paper presents two post-processing methods to improve the performance of hyperspherical classifiers in rejecting patterns from unknown classes. The first method uses a self-organizational approach to design minimum radius hyperspheres, reducing the redundancy of the class region defined by the hyperspherical classifiers. The second method removes additional redundant class regions from the hyperspheres by using a clustering technique to generate a number of smaller hyperspheres. Simulation and experimental results demonstrate that by removing redundant regions these two …

Quantification Of Bronchial Circulation Perfusion In Rats, Christian Wieholt, Robert C. Molthen, Steven Thomas Haworth, David L. Roerig, Christopher A. Dawson, Anne V. Clough

Biomedical Engineering Faculty Research and Publications

The bronchial circulation is thought to be the primary blood supply for pulmonary carcinomas. Thus, we have developed a method for imaging and quantifying changes in perfusion in the rat lung due to development of the bronchial circulation. A dual-modality micro-CT/SPECT system was used to detect change in perfusion in two groups of rats: controls and those with a surgically occluded left pulmonary artery. Both groups were imaged following injections on separate days i) 2mCi of Tc99m labeled macroaggregated albumin (MAA) into the left carotid artery (IA) and ii) a similar injection into the femoral vein (IV). The IA injection …

Post-Acquisition Small-Animal Respiratory Gated Imaging Using Micro Cone-Beam Ct, Jicun Hu, Steven Thomas Haworth, Robert C. Molthen, Christopher A. Dawson

Biomedical Engineering Faculty Research and Publications

On many occasions, it is desirable to image lungs in vivo to perform a pulmonary physiology study. Since the lungs are moving, gating with respect to the ventilatory phase has to be performed in order to minimize motion artifacts. Gating can be done in real time, similar to cardiac imaging in clinical applications, however, there are technical problems that have lead us to investigate different approaches. The problems include breath-to-breath inconsistencies in tidal volume, which makes the precise detection of ventilatory phase difficult, and the relatively high ventilation rates seen in small animals (rats and mice have ventilation rates in …

Changes In Pulmonary Arterial Wall Mechanical Properties And Lumenal Architecture With Induced Vascular Remodeling, Robert C. Molthen, Amy Heinrich, Steven Thomas Haworth, Christopher A. Dawson

Biomedical Engineering Faculty Research and Publications

To explore and quantify pulmonary arterial remodeling we used various methods including micro-CT, high-resolution 3-dimensional x-ray imaging, to examine the structure and function of intact pulmonary vessels in isolated rat lungs. The rat is commonly used as an animal model for studies of pulmonary hypertension (PH) and the accompanying vascular remodeling, where vascular remodeling has been defined primarily by changes in the vessel wall composition in response to hypertension inducing stimuli such as chronic hypoxic exposure (CHE) or monocrotaline (MCT) injection. Little information has been provided as to how such changes affect the vessel wall mechanical properties or the lumenal …

Optimal Calibration Of Pet Crystal Position Maps Using Gaussian Mixture Models, Kelly A. Stronger, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

A method is developed for estimating optimal PET gamma-ray detector crystal position maps, for arbitrary crystal configurations, based on a binomial distribution model for scintillation photon arrival. The approach is based on maximum likelihood estimation of Gaussian mixture model parameters using crystal position histogram data, with determination of the position map taken from the posterior probability boundaries between mixtures. This leads to minimum probability of error crystal identification under the assumed model.

Optimized Breakdown Probabilities In Al/Sub 0.6/Ga/Sub 0.4/As-Gaas Heterojunction Avalanche Photodiodes, Oh-Hyun Kwon, Majeed M. Hayat, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

Recently, it has been shown that the noise characteristics of heterojunction Al/sub 0.6/Ga/sub 0.4/As-GaAs avalanche photodiodes (APDs) can be optimized by proper selection of the width of the Al/sub 0.6/Ga/sub 0.4/As layer. Similar trends have also been shown theoretically for the bandwidth characteristics. The resulting noise reduction and potential bandwidth enhancement have been attributed to the fact that the high bandgap Al/sub 0.6/Ga/sub 0.4/As layer serves to energize the injected electrons, thereby minimizing their first dead space in the GaAs layer. We show theoretically that the same optimized structures yield optimal breakdown-probability characteristics when the APD is operated in Geiger …

Effect Of Stochastic Dead Space On Noise In Avalanche Photodiodes, Oh-Hyun Kwon, Majeed M. Hayat, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

A stochastic dead-space model for impact ionization is developed and used to study the effect of the soft nature of the ionization capability of carriers on the excess noise factor of avalanche photodiodes. The proposed model is based on the rationale that the gradual, or soft, transition in the probability density function (PDF) for the distance from birth to impact ionization can be viewed as that resulting from uncertainty in the dead space itself. The resulting soft PDF, which is parameterized by a tunable softness parameter, is used to establish the limitations of the existing hard-threshold ionization models in ultrathin …

Noise Simulations For An Inverse-Geometry Volumetric Ct System, Taly Gilat Schmidt, Rebecca Fahrig, Norbert J. Pelc

Biomedical Engineering Faculty Research and Publications

This paper examines the noise performance of an inverse-geometry volumetric CT (IGCT) scanner through simulations. The IGCT system uses a large area scanned source and a smaller array of detectors to rapidly acquire volumetric data with negligible cone-beam artifacts. The first investigation compares the photon efficiency of the IGCT geometry to a 2D parallel ray system. The second investigation models the photon output of the IGCT source and calculates the expected noise. For the photon efficiency investigation. the same total number of photons was modeled in an IGCT acquisition and a comparable multi-slice 2D parallel ray acquisition. For both cases …

Design Of Pid Controllers Satisfying Gain Margin And Sensitivity Constraints On A Set Of Plants, O. Yaniv, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

This paper presents a method for the design of PID-type controllers, including those augmented by a filter on the D element, satisfying a required gain margin and an upper bound on the (complementary) sensitivity for a finite set of plants. Important properties of the method are: (i) it can be applied to plants of any order including non-minimum phase plants, plants with delay, plants characterized by quasi-polynomials, unstable plants and plants described by measured data, (ii) the sensors associated with the PI terms and the D term can be different (i.e., they can have different transfer function models), (iii) the …