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Articles 1 - 30 of 38
Full-Text Articles in Engineering
Computational Modeling Of Biochemical Systems Using Cellular Automata, Advait Apte
Computational Modeling Of Biochemical Systems Using Cellular Automata, Advait Apte
Theses and Dissertations
Biological systems exhibit complex behaviors through coordinated responses of individual biological components. With the advent of genome-scale techniques, one focus has been to develop methods to model interactions between components to accurately describe intact system function. Mathematical modeling techniques such as constraint-based modeling, agent-based modeling, cellular automata (CA) modeling and differential equation modeling are employed as computational tools to study biological phenomenon. We have shown that cellular automata simulations can be used as a computational tool for 12 predicting the dynamics of biological systems with stochastic behavior. The basic premise for the research was the observations made during a study …
Investigation Of The Mechanical Properties Of Poly (Ethylene Glycol) Diacrylate By Nanoindentation Using Atomic Force Microscopy, Zouheir Drira
Investigation Of The Mechanical Properties Of Poly (Ethylene Glycol) Diacrylate By Nanoindentation Using Atomic Force Microscopy, Zouheir Drira
Theses and Dissertations
Poly (ethylene glycol) (PEG) hydrogel based polymers are among the most widely used synthetic materials for biomedical applications. Because of their biocompatibility, and ease of fabrication, hydrogels are highly suitable for use as constructs to engineer tissues as well as for cell transplantation. A critical parameter of importance for PEG hydrogels is their mechanical properties which are highly dependent on the environmental conditions. Properties of PEG-based hydrogels can be engineered to resemble scaffolds composed of extracellular matrix molecules, which provide structural support, adhesive sites and mechanical as well as biomechanical signals to most cells. The mechanical properties of these synthetic …
Oculomotor Control In Patients With Parkinson's Disease, George Gitchel
Oculomotor Control In Patients With Parkinson's Disease, George Gitchel
Theses and Dissertations
There have been few studies investigating the eye movement behavior of Parkinson’s disease patients during fixation. This study objectively measured the eye movements of 36 patients with Parkinson’s disease, and 20 age matched controls. Stimuli consisted of ten standardized text passages first organized by Miller and Coleman. In addition, subjects followed a randomly displaced step jump target motion. Pendular nystagmus was found in all Parkinson’s subjects, with an average frequency of 7.44 Hz. Saccadic peak velocity and duration along the main sequence were not statistically different from controls. A slower rate of reading was also noted in the Parkinson’s group …
Automated Methods For Fiber Diameter Measurement Of Fibrous Scaffolds, Anna Bulysheva
Automated Methods For Fiber Diameter Measurement Of Fibrous Scaffolds, Anna Bulysheva
Theses and Dissertations
The purpose of this work was to develop an automated method of measuring fiber diameters of electrospun scaffolds from scanning electron microscopy images of these scaffolds. Several automated methods were developed and evaluated by comparison to known values and data obtained via the standard manual method. Simulated images with known diameters were used as test images to evaluate the accuracy of each measurement technique. Eight scanning electron microscopy images were also used for the evaluation of the automated methods compared to the standard manual method. All diameter measurements were made in pixels. Five new automated methods coded in MATLAB were …
Efficient Implementation Of Raid-6 Encoding And Decoding On A Field Programmable Gate Array (Fpga), David Jacob
Efficient Implementation Of Raid-6 Encoding And Decoding On A Field Programmable Gate Array (Fpga), David Jacob
Theses and Dissertations
RAID-6 is a data encoding scheme used to provide single drive error detection and dual drive error correction for data redundancy on an array of disks. Here we present a thorough study of efficient implementations of RAID-6 on field programmable gate arrays (FPGAs). Since RAID-6 relies heavily on Galois Field Algebra (GFA), an efficient implementation of a GFA FPGA library is also presented. Through rigorous performance analysis, this work shows the most efficient ways to tradeoff FPGA resources and execution time when implementing GFA functions as well as RAID-6 encoding and decoding.
Experimental And Numerical Investigation On Pyroelectric Energy Scavenging, Jingsi Xie
Experimental And Numerical Investigation On Pyroelectric Energy Scavenging, Jingsi Xie
Theses and Dissertations
Pyroelectric energy scavenging is the process of converting wasted energy from a system to power another one, based on the pyroelectric effect of piezoelectric materials. Pyroelectrically generated power is a function of the surface of material, the pyroelectric coefficient, and the temporal temperature gradient. In the current project, a simple model is developed to predict the power generation based on the temporal change in temperature of material. In addition, a model is validated with experimental measurements from several piezoelectric materials. It is shown that energy generation can be enhanced by using piezoelectric materials with significantly higher pyroelectric coefficients such as …
Mechanical Structures Resisting Anterior Instability In A Computational Glenohumeral Joint Model, Kevin Elmore
Mechanical Structures Resisting Anterior Instability In A Computational Glenohumeral Joint Model, Kevin Elmore
Theses and Dissertations
The glenohumeral joint is the most dislocated joint in the body due to the lack of bony constraints and dependence on soft tissue, primarily muscles and ligaments, to stabilize the joint. The goal of this study was to develop a computational model of the glenohumeral joint whereby joint behavior was dictated by articular contact, ligamentous constraints, muscle loading, and external perturbations. Validation of this computational model was achieved by comparing predicted results from the model to the results of a cadaveric experiment in which the relative contribution of muscles and ligaments to anterior joint stability was examined. The results showed …
Gan Heterojunction Fet Device Fabrication, Characterization And Modeling, Qian Fan
Gan Heterojunction Fet Device Fabrication, Characterization And Modeling, Qian Fan
Theses and Dissertations
This dissertation is focused on the research efforts to develop the growth, processing, and modeling technologies for GaN-based Heterojunction Field Effect Transistors (HFETs). The interest in investigating GaN HFETs is motivated by the advantageous material properties of nitride semiconductor such as large band gap, large breakdown voltage, and high saturation velocity, which make it very promising for the high power and microwave applications. Although enormous progress has been made on GaN transistors in the past decades, the technologies for nitride transistors are still not mature, especially concerning the reliability and stability of the device. In order to improve the device …
Dilute Sulfuric Acid Pretreatment Of Switchgrass In Microwave Reactor For Biofuel Conversion: An Investigation Of Yields, Kinetics,, Oscar Martin
Theses and Dissertations
Lignocellulosic materials provide a raw material source for biofuel conversion and offer several advantages over fossil fuels- usage of a renewable resource, reduced greenhouse emissions, a decreased dependence on foreign oil, and stimulation of the agricultural sector. However, a primary technological challenge in converting lignocellulosic biomass into fuel is overcoming the recalcitrance of its matrix to enzymatic hydrolysis. To overcome these problems for chemical processing, naturally occurring cellulose biomass must be pretreated before it can be further processed using enzymatic hydrolysis or bioconversion. The goal of this work was to develop a model that predicts the glucose yield (pretreatment and …
Development Of Rapid Die Wear Test Method For Assessment Of Die Life And Performance In Stamping Of Advanced/Ultra High Strength Steel (A/Uhss) Sheet Materials, Omer Necati Cora
Development Of Rapid Die Wear Test Method For Assessment Of Die Life And Performance In Stamping Of Advanced/Ultra High Strength Steel (A/Uhss) Sheet Materials, Omer Necati Cora
Theses and Dissertations
Automotive companies are actively pursuing to increase the use of high-strength-lightweight alloys such as aluminum, magnesium, and advanced/ultra high-strength steels (A/UHSS) in body panel and structural part applications to achieve fuel efficiency while satisfying several environmental and safety concerns. A/UHSS sheet materials with higher strength and crashworthiness capabilities, in comparison to mild steel alloys, are considered as a near-term (i.e., ~5 years) choice of material for body and structural components due to their relatively low cost when compared with other lightweight materials such as aluminum and magnesium. However, A/UHSS materials present an increased level of die wear and springback in …
Design And Development Of A Pvdf Sensor To Monitor Intracranial Pressure (Icp), Vivek Vijaywargi
Design And Development Of A Pvdf Sensor To Monitor Intracranial Pressure (Icp), Vivek Vijaywargi
Theses and Dissertations
Monitoring ICP non-invasively is a challenge. A novel method to measure ICP using actuators and sensors has been proposed where the skull is vibrated at high frequencies and the receiving signal is measured at the surface eyelid. A design of experiments approach is used to develop the sensor part of the ICP monitoring device so that gain can be maximized using factors such as area, thickness, electrode, and applied pressure. Statistical analysis showed that thickness has the biggest effect on overall gain. Numerical analysis confirmed these results. In addition, sensor packaging is optimized to minimize dampening of the signal and …
Mechanical Behavior And Length Adaptation Of Rabbit Bladder Smooth Muscle, Atheer Almasri
Mechanical Behavior And Length Adaptation Of Rabbit Bladder Smooth Muscle, Atheer Almasri
Theses and Dissertations
Overactive bladder (OAB), involuntary contractions during bladder filling, is a common condition affecting 17% of the adult population worldwide, and in the U.S. ranks ahead of diabetes in a list of the 10 most common chronic disorders (Mullins 2009). Mechanical mechanisms contributing to OAB are not completely understood and because of the unique function and broad volume range of the bladder, there may be mechanical characteristics that distinguish detrusor smooth muscle (DSM) in bladder from other smooth muscles. Recent studies have shown that the length-passive tension curve in DSM exhibits adjustable passive stiffness (APS) characterized by a passive curve that …
The Design And Validation Of A Computational Rigid Body Model Of The Elbow., Edward Spratley
The Design And Validation Of A Computational Rigid Body Model Of The Elbow., Edward Spratley
Theses and Dissertations
The use of computational modeling is an effective and inexpensive way to predict the response of complex systems to various perturbations. However, not until the early 1990s had this technology been used to predict the behavior of physiological systems, specifically the human skeletal system. To that end, a computational model of the human elbow joint was developed using computed topography (CT) scans of cadaveric donor tissue, as well as the commercially available software package SolidWorks™. The kinematic function of the joint model was then defined through 3D reconstructions of the osteoarticular surfaces and various soft-tissue constraints. The model was validated …
Development Of A Mechanical Cavopulmonary Assist Device For The Failing Fontan Patients, Jugal Kapadia
Development Of A Mechanical Cavopulmonary Assist Device For The Failing Fontan Patients, Jugal Kapadia
Theses and Dissertations
The long term objective of this research is to develop a collapsible, percutaneously inserted, axial flow blood pump to improve blood flow in the cavopulmonary circulation. Through this research, the experimental evaluation of five blood pump prototypes and hemolysis testing of one blood pump prototype were performed. All prototypes demonstrated acceptable hydraulic performance. A comparison of the experimental results with numerical predictions demonstrated a 10-20% deviation, an acceptable range per industry standard. Hemolysis testing of a four bladed adult blood pump showed plasma free hemoglobin level of 20.04 mg/dL and maximum NIH (normalized index of hemolysis) level was 0.017 g/100L. …
Design And Optimization Of Peristaltic Micropumps Using Evolutionary Algorithms, Ravi Bhadauria
Design And Optimization Of Peristaltic Micropumps Using Evolutionary Algorithms, Ravi Bhadauria
Theses and Dissertations
A design optimization based on coupled solid–fluid analysis is investigated in this work to achieve specific flow rate through a peristaltic micropump. A micropump consisting of four pneumatically actuated nozzle/diffuser shaped moving actuators on the sidewalls is considered for numerical study. These actuators are used to create pressure difference in the four pump chambers, which in turn drives the fluid through the pump in one direction. Genetic algorithms along with artificial neural networks are used for optimizing the pump geometry and the actuation frequency. A simple example with moving walls is considered for validation by developing an exact analytical solution …
Preparation And Characterization Of An Electrospun Gelatin/Dendrimer Hybrid Nanofiber Dressing, Alicia P. Smith-Freshwater
Preparation And Characterization Of An Electrospun Gelatin/Dendrimer Hybrid Nanofiber Dressing, Alicia P. Smith-Freshwater
Theses and Dissertations
A novel dendritic wound dressing was designed and characterized for its potential to treat chronic wounds. Comprised of gelatin, dendrimer, synthetic polymer and antibiotics, the dressing was electrospun to mimic the natural extracellular matrix (ECM). Gelatin is biocompatible, biodegradable, non-toxic, and easily available. The antibiotic, doxycycline, has the ability to inhibit matrix metalloproteinases. Matrix metalloproteinases, which occur in excess in chronic wounds, degrade the reconstituted ECM. Starburst™ polyamidoamine (PAMAM) dendrimer G3.5, which provides a versatile and structurally controlled architecture to construct nanomedicine, was covalently bonded to the gelatin backbone and electrospun into nanofibers with gelatin, doxycycline and stabilizing polymers. The …
Controlled Release Of Fluoride From Poly(Ethylene-Co-Vinyl Acetate) Films, Shadeed Khan
Controlled Release Of Fluoride From Poly(Ethylene-Co-Vinyl Acetate) Films, Shadeed Khan
Theses and Dissertations
The development of aesthetically unattractive white spots is a concern for patients undergoing fixed orthodontic treatment. Due to poor oral hygiene during treatment, accumulation of plaque around orthodontic brackets causes bacterial fermentation reactions producing acids that dissolve the mineral enamel. Such dissolution results in white spot formation, an early sign of dental caries. In principal, to inhibit the appearance of these spots during treatment, fluoridated elastomeric o-rings might be employed. Once placed around brackets, these o-rings should release fluoride therapeutically for at least 30 days, after which the orthodontist may replace them. At the present time, such fluoride-releasing o-rings are …
The Use Of A Tri-Axial Accelerometer To Measure Changes In Lower Extremity Fatigue During Functional Activity, Kristin Morgan
The Use Of A Tri-Axial Accelerometer To Measure Changes In Lower Extremity Fatigue During Functional Activity, Kristin Morgan
Theses and Dissertations
In 2004, the National Collegiate Athletic Association reported ankle sprain as the most frequent injury in soccer, basketball, and volleyball players. Further research found an increased likelihood with fatigue. Measuring fatigue during functional activities has been a longstanding problem. In this study, changes in ankle biomechanics were measured using a tri-axial accelerometer embedded in the shoe as subjects (n=12) performed a fatiguing activity. Data were collected from the accelerometer and from established devices that are considered the industry gold standard. Several kinetic and kinematic accelerometer derived variables were highly correlated with these standards (r2>0.90) and were associated with changes …
Spatial Detection Of Multiple Movement Intentions From Sam-Filtered Single-Trial Meg For A High Performance Bci, Harsha Battapady
Spatial Detection Of Multiple Movement Intentions From Sam-Filtered Single-Trial Meg For A High Performance Bci, Harsha Battapady
Theses and Dissertations
The objective of this study is to test whether human intentions to sustain or cease movements in right and left hands can be decoded reliably from spatially filtered single trial magneto-encephalographic (MEG) signals. This study was performed using motor execution and motor imagery movements to achieve a potential high performance Brain-Computer interface (BCI). Seven healthy volunteers, naïve to BCI technology, participated in this study. Signals were recorded from 275-channel MEG and synthetic aperture magnetometry (SAM) was employed as the spatial filter. The four-class classification for natural movement intentions was performed offline; Genetic Algorithm based Mahalanobis Linear Distance (GA-MLD) and direct-decision …
Development Of An Electroencephalography-Based Brain-Computer Interface Supporting Two-Dimensional Cursor Control, Dandan Huang
Development Of An Electroencephalography-Based Brain-Computer Interface Supporting Two-Dimensional Cursor Control, Dandan Huang
Theses and Dissertations
This study aims to explore whether human intentions to move or cease to move right and left hands can be decoded from spatiotemporal features in non-invasive electroencephalography (EEG) in order to control a discrete two-dimensional cursor movement for a potential multi-dimensional Brain-Computer interface (BCI). Five naïve subjects performed either sustaining or stopping a motor task with time locking to a predefined time window by using motor execution with physical movement or motor imagery. Spatial filtering, temporal filtering, feature selection and classification methods were explored. The performance of the proposed BCI was evaluated by both offline classification and online two-dimensional cursor …
The Production And Filtration Efficiency Testing Of Nonwoven Electrospun Fiber Mats, Jan Uecker
The Production And Filtration Efficiency Testing Of Nonwoven Electrospun Fiber Mats, Jan Uecker
Theses and Dissertations
In this thesis the production and filtration performance of electrospun nylon-4,6 nanofiber mats was experimentally studied. The average fiber diameter of nylon-4,6 fibers is controlled by altering the polymer concentration in solution. Adding small amount of pyridine to the electrospinning solution controlled fiber beading and other defects. These fibers were then deposited onto a wide variety of conductive and dielectric substrate materials. A corona ion source was used to eliminate surface charging effects observed at the surface of all substrates. The resulting fiber mats, uniform in size and distribution as verified by SEM imaging, are tested for filtration efficiency and …
Fabrication And Characterization Of Bioactive, Composite Electrospun Bone Tissue Engineering Scaffolds Intended For Cleft Palate Repair, Parthasarathy Madurantakam
Fabrication And Characterization Of Bioactive, Composite Electrospun Bone Tissue Engineering Scaffolds Intended For Cleft Palate Repair, Parthasarathy Madurantakam
Theses and Dissertations
Tissue Engineering is a scientific discipline that aims to regenerate tissues and organs that are diseased, lost or congenitally absent. It encompasses the use of suitable synthetic equivalents of native extracellular matrix that may or may not be supplemented with cells or relevant growth factors. Such scaffolds are designed to reside at the site of implantation for a variable period of time during which they induce the regeneration of native tissue. During this time, they also provide a template for new cells to attach, infiltrate, differentiate into appropriate phenotype and eventually restore function of the concerned tissue. Among the factors …
Computational Modeling Of The Helical Axis In The Human Knee--Detecting Changes In The Transverse Plane, Emily Carney
Computational Modeling Of The Helical Axis In The Human Knee--Detecting Changes In The Transverse Plane, Emily Carney
Theses and Dissertations
The purpose of this study was to build a helical axis algorithm capable of detecting changes in the helical axis intersection of the tibia and femur in human knees. This algorithm was designed and tested using three models: a multiplanar rigid body model, a mathematical model, and a cylinder model. The multiplanar rigid body model closely mimics knee movement without supporting ligamentous structures, thus the movement was unconstrained. In this model kinematic position data were collected using both MotionMonitor™ (MotionMonitor™ Version 7.7, Innovative Sports Training, Chicago, IL) and Vicon Nexus 1.3 software system (Oxford Metrics Group, Oxford, UK). To test …
Controlled Synthesis Of Zno Nanowires Towards The Fabrication Of Solar Cells, Dongshan Yu
Controlled Synthesis Of Zno Nanowires Towards The Fabrication Of Solar Cells, Dongshan Yu
Theses and Dissertations
In recent years, quasi-one-dimensional materials have attracted a lot of research attention due to their remarkable properties, and their potential as building blocks for nanoscale electronic and optoelectronic devices. A modified chemical vapor deposition (CVD) method has been used to synthesize ZnO nanowires. Electron microscopy and other characterization techniques show that nanowires having distinct morphologies when grown under different conditions. The effects of reaction parameters including reaction time, temperature, carrier gas flow rate, substrates and catalyst material upon the size, shape, and density of ZnO nanowire arrays have been investigated. Excitonic solar cells —including Gratzel-type cells, organic and hybrid organic/inorganic …
Tissue Engineering Cellularized Silk-Based Ligament Analogues, Scott Sell
Tissue Engineering Cellularized Silk-Based Ligament Analogues, Scott Sell
Theses and Dissertations
The resurgence, and eventual rise to prominence in the field of tissue engineering, that electrospinning has experienced over the last decade speaks to the simplicity and adaptability of the process. Electrospinning has been used for the fabrication of tissue engineering scaffolds intended for use in nearly every part of the human body: blood vessel, cartilage, bone, skin, nerve, connective tissue, etc. Diverse as the aforementioned tissues are in both form and function, electrospinning has found a niche in the repair of each due to its capacity to consistently create non-woven structures of fibers ranging from nano-to-micron size in diameter. These …
Growth, Characterization And Applications Of Multifunctional Ferroelectric Thin Films, Bo Xiao
Growth, Characterization And Applications Of Multifunctional Ferroelectric Thin Films, Bo Xiao
Theses and Dissertations
Ferroelectric materials have been extensively studied theoretically and experimentally for many decades. Their ferroelectric, piezoelectric, pyroelectric, dielectric and electro-optical properties offer great promise in various applications such as non-volatile random access memory devices, non linear optics, motion and thermal sensors, and tunable microwave devices. Advanced applications for high dielectric constant insulators and nonvolatile memories in semiconductor industry have led to a meteoric rise of interest in the ferroelectrics recently. As most studied and technically important ferroelectric materials, lead zirconate titanate (PZT) and barium strontium titanate (BST) are widely investigated to understand their properties for potential device applications. Using radio frequency …
Integrated Actuation And Energy Harvesting In Prestressed Piezoelectric Synthetic Jets, Poorna Mane
Integrated Actuation And Energy Harvesting In Prestressed Piezoelectric Synthetic Jets, Poorna Mane
Theses and Dissertations
With the looming energy crisis compounded by the global economic downturn there is an urgent need to increase energy efficiency and to discover new energy sources. An approach to solve this problem is to improve the efficiency of aerodynamic vehicles by using active flow control tools such as synthetic jet actuators. These devices are able to reduce fuel consumption and streamlined vehicle design by reducing drag and weight, and increasing maneuverability. Hence, the main goal of this dissertation is to study factors that affect the efficiency of synthetic jets by incorporating energy harvesting into actuator design using prestressed piezoelectric composites. …
Fabrication And Device Applications Of Self Assembled Nanostructures, Bhargava Ram Kanchibotla V
Fabrication And Device Applications Of Self Assembled Nanostructures, Bhargava Ram Kanchibotla V
Theses and Dissertations
The spin dynamics of electrons in inorganic and organic semiconducting nanostructures has become an area of interest in recent years. The controlled manipulation of an electron’s spin, and in particular its phase, is the primary requirement for applications in quantum information processing. The phase decoheres in a time known as the transverse relaxation time or T2 time. We have carried out a measurement of the ensemble-averaged transverse spin relaxation time (T2*) in bulk and few molecules of the organic semiconductor tris-(8-hydroxyquinolinolato aluminum) or Alq3. The Alq3 system exhibits two characteristic T2* times: the longer of which is temperature independent and …
Multiscale Modeling Of Airway Inflammation Induced By Mechanical Ventilation, Kittisak Koombua
Multiscale Modeling Of Airway Inflammation Induced By Mechanical Ventilation, Kittisak Koombua
Theses and Dissertations
Mechanical ventilation (MV) is a system that partially or fully assists patients whose respiratory system fails to achieve a gas exchange function. However, MV can cause a ventilator-associated lung injury (VALI) or even contribute to a multiple organ dysfunction syndrome (MODS) in acute respiratory distress syndrome (ARDS) patients. Despite advances in today technologies, mortality rates for ARDS patient are still high. A better understanding of the interactions between airflow from mechanical ventilator and the airway could provide useful information used to develop a better strategy to ventilate patients. The mechanisms, which mechanical ventilation induces airway inflammation, are complex processes and …
A Parallel Molecular Dynamics Program For Simulation Of Water In Ion Channels, Laxmi Mullapudi
A Parallel Molecular Dynamics Program For Simulation Of Water In Ion Channels, Laxmi Mullapudi
Theses and Dissertations
With a modest beginning from developing a model of dynamics of hard liquid spheres (Alder et al., 1957), molecular dynamics (MD) simulations have come to a point where complex biomolecules can be simulated with precision close to reality (Noskov et al., 2007). In this context, a parallel molecular dynamics program for simulation of ion channels associated with cellular membranes has been developed. The parallel MD code developed is simple, efficient, and easily coupled to other codes such as the hybrid molecular dynamics/ brownian dynamics (MD/BD) code developed for the study of protein interactions (Ying et al., 2005). The Atom Decomposition …