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Articles 1 - 30 of 37
Full-Text Articles in Engineering
Time Relaxed Round Robin Tournament And The Nba Scheduling Problem, Renjun Bao
Time Relaxed Round Robin Tournament And The Nba Scheduling Problem, Renjun Bao
ETD Archive
This dissertation study was inspired by the National Basketball Association regular reason scheduling problem. NBA uses the time-relaxed round robin tournament format, which has drawn less research attention compared to the other scheduling formats. Besides NBA, the National Hockey League and many amateur leagues use the time-relaxed round robin tournament as well. This dissertation study is the first ever to examine the properties of general time-relaxed round robin tournaments. Single round, double round and multiple round time-relaxed round robin tournaments are defined. The integer programming and constraint programming models for those tournaments scheduling are developed and presented. Because of the …
Application Of Dual-Energy Computed Tomography To The Evalution Of Coronary Atherosclerotic Plaque, Mitya M. Barreto
Application Of Dual-Energy Computed Tomography To The Evalution Of Coronary Atherosclerotic Plaque, Mitya M. Barreto
ETD Archive
Atherosclerotic coronary artery disease is responsible for around 50 of cardiovascular deaths in USA. Early detection and characterization of coronary artery atherosclerotic plaque could help prevent cardiac events. Computed tomography (CT) is an excellent modality for imaging calcifications and has higher spatial resolution than other common non-invasive modalities (e.g MRI), making it more suitable for coronary plaque detection. However, attenuation-based classification of non-calcified plaques as fibrous or lipid is difficult with conventional CT, which relies on a single x-ray energy. Dual-energy CT (DECT) may provide additional attenuation data for the identification and discrimination of plaque components. The purpose of this …
Subject Specific Computational Models Of The Knee To Predict Anterior Cruciate Ligament Injury, Bhushan S. Borotikar
Subject Specific Computational Models Of The Knee To Predict Anterior Cruciate Ligament Injury, Bhushan S. Borotikar
ETD Archive
Knee joint is a complex joint involving multiple interactions between cartilage, bone, muscles, ligaments, tendons and neural control. Anterior Cruciate Ligament (ACL) is one ligament in the knee joint that frequently gets injured during various sports or recreational activities. ACL injuries are common in college level and professional athletes especially in females and the injury rate is growing in epidemic proportions despite significant increase in the research focusing on neuromuscular and proprioceptive training programs. Most ACL injuries lead to surgical reconstruction followed by a lengthy rehabilitation program impacting the health and performance of the athlete. Furthermore, the athlete is still …
Development Of A Focused Broadband Ultrasonic Transducer For High Resolution Fundamental And Harmonic Intravascular Imaging, Chaitanya K. Chandrana
Development Of A Focused Broadband Ultrasonic Transducer For High Resolution Fundamental And Harmonic Intravascular Imaging, Chaitanya K. Chandrana
ETD Archive
Intravascular ultrasound (IVUS) is increasingly employed for detection and evaluation of coronary artery diseases. Tissue Harmonic Imaging provides different tissue information that could additionally be used to improve diagnostic accuracy. However, current IVUS systems, with their unfocussed transducers, may not be capable of operating in harmonic imaging mode. Thus, there is a need to develop suitable transducers and appropriate techniques to allow imaging in multi modes for complementary diagnostic information. Focused PVDF TrFE transducers were developed using MEMS (Micro-Electro-Mechanical-Systems) compatible protocols. The transducers were characterized using pulse-echo techniques and exhibited broad bandwidth (110 at -6dB) with axial resolutions of Such …
Altered Cortico-Cortical Brain Connectivity During Muscle Fatigue, Zhiguo Jiang
Altered Cortico-Cortical Brain Connectivity During Muscle Fatigue, Zhiguo Jiang
ETD Archive
Traditional brain activation studies using neuroimaging such as functional magnetic imaging (fMRI) have shown that muscle fatigue at submaximal intensity level is associated with increased brain activity in various cortical regions from low- to high-order motor centers. However, how these areas might interact remain unclear since previous activation studies related to motor control could not reveal information of between-area interaction. This issue can be addressed by evaluating brain activation data using the framework of connectivity analysis. Three types of brain connectivity, functional connectivity (FC), effective connectivity (EC) and structural connectivity (SC) have been examined to investigate the effect of voluntary …
In-Situ Growth Of Porous Alumino-Silicates And Fabrication Of Nano-Porous Membranes, Pradeep Kodumuri
In-Situ Growth Of Porous Alumino-Silicates And Fabrication Of Nano-Porous Membranes, Pradeep Kodumuri
ETD Archive
Feasibility of depositing continuous films of nano-porous alumino-silicates, primarily zeolites and MCM-41, on metallic and non-metallic substrates was examined with an aim to develop membranes for separation of gaseous mixtures and also for application as hydrogen storage material. Mesoporous silica was deposited in-side the pores of these nano-porous disks with an aim to develop membranes for selective separations. Our study involves supported zeolite film growth on substrates using in-situ hydrothermal synthesis. Faujasite, Silicalite and Mesoporous silica have been grown on various metallic and non-metallic supports. Metallic substrates used for film growth included anodized titanium, sodium hydroxide treated Titanium, Anodized aluminum, …
Increasing Pile Capacity And Set-Up In Clay By Electrokinetics, Susheel R. Kolwalkar
Increasing Pile Capacity And Set-Up In Clay By Electrokinetics, Susheel R. Kolwalkar
ETD Archive
A significant increase in the load capacity over a period of time is often observed in driven piles. This time dependent strength gain is termed as 'set-up'. Different mechanisms have been proposed to explain the set-up phenomenon in cohesive soils. A research was initiated to investigate this mechanism in clay soils in terms of electrokinetic theory and explore the possibility of accelerating the process. The system chosen for the study consisted of laboratory scale steel piles driven in kaolinite clay under controlled conditions. The piles were subjected to DC voltage gradients with surrounding electrodes at different time intervals and their …
Imaging Of Tyramine-Substituted Hydrogels For Tissue Replacement, Ediuska V. Laurens
Imaging Of Tyramine-Substituted Hydrogels For Tissue Replacement, Ediuska V. Laurens
ETD Archive
Novel tyramine-based hyaluronan (HA) and collagen hydrogels have been developed in which cross-linking is accomplished via peroxidase-mediated dityramine linkages allowing direct cross-linking in vivo. These TB hydrogels possess advantageous physical properties, which include excellent biocompatibility and the ability to mimic the biological, structural and mechanical properties of normal, healthy tissues, including cartilage, and thus provide for synthetic, implantable biomaterials suitable for a wide range of tissue types. The efficacy of these TB-hydrogels has been previously tested in a number of clinically relevant animal models, which have evaluated their applicability for the repair/replacement of various tissues, including cartilage. Nevertheless, there exists …
Semi-Automatic Segmentation Of Normal Female Pelvic Floor Structures From Magnetic Resonance Images, Xiaolong Li
Semi-Automatic Segmentation Of Normal Female Pelvic Floor Structures From Magnetic Resonance Images, Xiaolong Li
ETD Archive
Stress urinary incontinence (SUI) and pelvic organ prolapse (POP) are important health issues affecting millions of American women. Investigation of the cause of SUI and POP requires a better understand of the anatomy of female pelvic floor. In addition, pre-surgical planning and individualized treatment plans require development of patient-specific three-dimensional or virtual reality models. The biggest challenge in building those models is to segment pelvic floor structures from magnetic resonance images because of their complex shapes, which make manual segmentation labor-intensive and inaccurate. In this dissertation, a quick and reliable semi-automatic segmentation method based on a shape model is proposed. …
Uncertainty Management Of Intelligent Feature Selection In Wireless Sensor Networks, Sanchita Mal-Sarkar
Uncertainty Management Of Intelligent Feature Selection In Wireless Sensor Networks, Sanchita Mal-Sarkar
ETD Archive
Wireless sensor networks (WSN) are envisioned to revolutionize the paradigm of monitoring complex real-world systems at a very high resolution. However, the deployment of a large number of unattended sensor nodes in hostile environments, frequent changes of environment dynamics, and severe resource constraints pose uncertainties and limit the potential use of WSN in complex real-world applications. Although uncertainty management in Artificial Intelligence (AI) is well developed and well investigated, its implications in wireless sensor environments are inadequately addressed. This dissertation addresses uncertainty management issues of spatio-temporal patterns generated from sensor data. It provides a framework for characterizing spatio-temporal pattern in …
Two Approaches For Cell Retention In Perfusion Culture Systems, Zhaowei Wang
Two Approaches For Cell Retention In Perfusion Culture Systems, Zhaowei Wang
ETD Archive
A lack of efficient, economical, and reliable cell retention devices has limited the application of perfusion culture systems in the biopharmaceutical industry. Two types of cell retention devices were developed in this work for long-term perfusion culture systems: a modification of an inclined gravity settler and a variation of an ultrasonic filter. Both bench-top and large-scale tests showed that the gravity settler can effectively retain viable cells and preferentially remove nonviable cells in perfusion culture systems. The viable cell retention rate can be maintained well above 90 during long-term perfusion culture period while the nonviable cell retention rate is 20-30 …
Cortical Bone Tissue Engineering;Scaffold Design And Cell Selection, Demin Wen
Cortical Bone Tissue Engineering;Scaffold Design And Cell Selection, Demin Wen
ETD Archive
Cortical bone tissue engineering provides a promising approach to generate graft materials needed to treat the large sized bone defects. The underling premise of tissue engineering is to mimic the in vivo microenvironment as best as possible in vitro culture system. To select an appropriate scaffold material used in this model system, mechanical and hydraulic permeability properties of 316L porous stainless steel and polymethylmethacrylate (PMMA) were studied, as well as their biocompatibility in short and long term cell culture. Results showed that scaffolds made of both stainless steel and PMMA: (1) could be manufactured to have similar permeability as that …
On Active Disturbance Rejection Control;Stability Analysis And Applications In Disturbance Decoupling Control, Qing Zheng
ETD Archive
One main contribution of this dissertation is to analyze the stability characteristics of extended state observer (ESO) and active disturbance rejection control (ADRC). In particular, asymptotic stability of the dynamic system that describes the estimation error and the closed-loop system is established where the plant dynamics is completely known. In the face of large dynamic uncertainties, the estimation error, the closed-loop tracking error, and its up to the (n-1)st order derivatives are shown to be bounded. Furthermore, it is demonstrated that the error upper bounds, in general, monotonously decrease with the observer and control loop bandwidths. The second contribution is …
Robotics Control Using Active Disturbance Rejection Control, Ousama Said Khairallah
Robotics Control Using Active Disturbance Rejection Control, Ousama Said Khairallah
ETD Archive
Conventional robotics control has been set in stone since the sixties. The world has been waiting too long for a new age of control to change the world of Robotics. Active Disturbance Rejection Control (ADRC) is a newly reformed Control methodology. It has been used, in very limited applications, as a replacement for PID control. In this thesis, I will cover the different aspects of the kinematics and dynamics of a robotic manipulator. I will also examine the feasibility of using ADRC to control a robotic manipulator. To explain ADRC, a simple example that demonstrates the concepts and theory of …
Flow Measurements In Turbulent Flow Fields With Magnetic Resonance Phase Velocity Mapping, Navneeth Sagar Reddy Lakkadi
Flow Measurements In Turbulent Flow Fields With Magnetic Resonance Phase Velocity Mapping, Navneeth Sagar Reddy Lakkadi
ETD Archive
Arterial stenosis (narrowing) is due to vascular disease that, if untreated, leads to death. The stenosis causes the development of complex flow which results in high energy losses and great forces between blood and tissue. Traditionally, turbulent flows lead to signal loss in magnetic resonance (MR) image acquisitions, resulting in loss of diagnostic information. With the advancement in MR hardware and software, some of the limitations of MR in turbulent flow fields may have been reduced or eliminated. This study evaluated the potential of MR phase velocity mapping (MRPVM), a clinical velocimetry technique, under turbulent flow conditions such as those …
Modeling And Feedback Control Of A Mems Electrostatic Actuator, Jason Edwards
Modeling And Feedback Control Of A Mems Electrostatic Actuator, Jason Edwards
ETD Archive
This thesis describes the mathematical modeling and closed-loop voltage control of a MEMS electrostatic actuator. The control goal is to extend the travel range of the actuator beyond the open-loop pull-in limit of one third of the initial gap. Three controller designs are presented to reach the control goal. The first controller design utilizes a regular fourth order Active Disturbance Rejection Controller (ADRC) and is able to achieve 97 of the maximum travel range. The second design also uses a fourth order ADRC, while additional modeling information is included in an Extended State Observer (ESO), which is part of the …
Load Frequency Control Of Multiple-Area Power Systems, Yao Zhang
Load Frequency Control Of Multiple-Area Power Systems, Yao Zhang
ETD Archive
In an interconnected power system, as a power load demand varies randomly, both area frequency and tie-line power interchange also vary. The objectives of load frequency control (LFC) are to minimize the transient deviations in theses variables (area frequency and tie-line power interchange) and to ensure their steady state errors to be zeros. When dealing with the LFC problem of power systems, unexpected external disturbances, parameter uncertainties and the model uncertainties of the power system pose big challenges for controller design. Active disturbance rejection control (ADRC), as an increasingly popular practical control technique, has the advantages of requiring little information …
A Frequency Response Based Approach To Dc-Dc Control Loop Design, Jack Andrew Redilla
A Frequency Response Based Approach To Dc-Dc Control Loop Design, Jack Andrew Redilla
ETD Archive
This thesis encompasses control theory, mathematical models and practical methods for developing high performance control loops for compact DC-DC power converters. In this research we compare an existing hardware control loop design developed through traditional empirical tuning methods to a control loop established by a proposed systematic design approach. To address the many problems of ad-hoc controller design for DC-DC converters, we develop a procedure utilizing tools from frequency domain analysis and loop shaping techniques. This design approach is used to ensure control loop stability and to verify improved loop performance. This systematic control loop design procedure can be utilized …
Probabilistic Stress Analysis Of Liquid Storage Tank, Khader A. Khan
Probabilistic Stress Analysis Of Liquid Storage Tank, Khader A. Khan
ETD Archive
Liquefied Natural Gas transport and storage has become very important due to its ability to occupy 1/600th of the volume that compressed natural gas would occupy at room temperature and atmospheric pressure. In the present work, an LNG storage tank has been computationally simulated and probabilistically evaluated in view of the several uncertainties in the fluid, structural, material and thermal variables that govern the LNG storage tank. A finite element code ALGOR was used to couple the thermal profiles with structural design. The stresses and their variations were evaluated at critical points on the storage tank. Cumulative distribution functions and …
Structural And Thermal Analysis Of Flange For Lng Applications, Mayank D. Kalbhor
Structural And Thermal Analysis Of Flange For Lng Applications, Mayank D. Kalbhor
ETD Archive
Structural and thermal analysis of the flange used in connection with hose for the transportation of LNG was computationally simulated by the method of finite element and probabilistically evaluated in view of the several uncertainties in the performance parameters. The distribution function and sensitivity factors for the maximum stresses were found out. The effect of various random variables including geometry, structural/thermal properties etc on the maximum stresses were studied probabilistically. These results were useful to identify the most critical random variable in order to optimize the design well before it is introduced in the market. This reduces the manufacturing cost …
Heat Transfer In Electroosmotic Flow Of Power-Law Fluids In Micro-Channel, Omkareshwar Rao Bakaraju
Heat Transfer In Electroosmotic Flow Of Power-Law Fluids In Micro-Channel, Omkareshwar Rao Bakaraju
ETD Archive
The present study examines heat transfer in electro-osmotic flow of power-law fluids in a micro-channel analytically. The boundary layer equations governing the flow of power-law fluids in a micro-channel have been solved. Heat transfer characteristics such as the temperature distribution and Nusselt number are presented for parametric values of electro-kinetic parameter kH(where k-1 is the Debye length and H is semi-channel height of the micro-channel) and Brinkman number. Uniform surface heat flux boundary condition has been considered. The effects of the Brinkman number on the Nusselt number for specific values of the flow behavior index (n) are analytically determined. This …
The Synthesis And Characterization Of Novel Elastin-Like Polypeptides Containing An Oligomerization Domain, James T. Cole
The Synthesis And Characterization Of Novel Elastin-Like Polypeptides Containing An Oligomerization Domain, James T. Cole
ETD Archive
Elastin like polypeptides (ELPs) are an emerging class of biomaterials due to their unique group of chemical, physical and biological properties. We have constructed a library of ELPs based on the pentapeptide amino acid repeat sequence (GVGVP). ELPs exhibit lower critical solution temperature (LCST) transition behavior from a soluble phase below the transition temperature (Tt) to an insoluble two phase system above the transition temperature. This process is completely reversible so that ELPs can become soluble again upon lowering the temperature. This temperature can be tuned in many different ways at the molecular level by changing the composition of the …
Investigation Of Generalized Dsss Under Multiple Access And Multipath, Indrasena Varakantham
Investigation Of Generalized Dsss Under Multiple Access And Multipath, Indrasena Varakantham
ETD Archive
In this thesis we investigate and compare the average performances of ordinary and generalized direct sequence spread spectrum (DSSS) systems under multi-path fading and multiple-access interference. As part of multiple access performance, we also consider generation of orthogonal and semi-orthogonal codes using various algorithms, and compare cross correlation properties of codes formed by 2-level and 3-level signature sequences. In order to simulate ordinary and generalized DSSS performance under various scenarios, we develop a complete Java library with classes that are well encapsulated with regard to communication modules and loosely coupled so that we can reuse them to create any type …
Effect Of Rib Turbulators On Heat Transfer Performance In Stationary Ribbed Channels, Aravind Rohan Sampath
Effect Of Rib Turbulators On Heat Transfer Performance In Stationary Ribbed Channels, Aravind Rohan Sampath
ETD Archive
The thermal performance was examined computationally for the stationary channels with rib turbulators oriented at 90 degrees. Ribs were placed on opposite walls and the heat transfer coefficients and frictional loss were calculated. Three stationary channels with aspect ratios (W/H) 1, 2 and 4 were considered for the analysis. The thermal performance was measured by calculating the Nusselt number and frictional losses. Square ribs (w/e = 1) were considered as the baseline configuration. The rib width and rib spacing varies while the rib height is maintained constant. Rib spacing (P/e) of 10 and 20 and rib width to rib height …
Biological Treatment Of Dietary Supplement Wastewater, Erick Benjamin Butler
Biological Treatment Of Dietary Supplement Wastewater, Erick Benjamin Butler
ETD Archive
Dietary supplement wastewater contains higher order polysaccharides such as the complex sugars maltodextrin and low fat milk. These complex sugars contain a significant amount of organic carbon therefore, presence of these sugars can pose threats to the environment if discharged without treatment. While many food processing plants are required to send their waste through wastewater treatment, legislation may require preliminary treatment of these wastes in order to satisfy the effluent discharge requirements. Because of the high organic carbon presence, it would be preferable to use biological treatment methods to reduce the organics present within the system. Microorganisms are capable of …
Wind Flow Induced Vibrations Of Tapered Masts, Ahmad Bani-Hani
Wind Flow Induced Vibrations Of Tapered Masts, Ahmad Bani-Hani
ETD Archive
Structural dynamic analyses of elongated masts subjected to various wind speeds are presented in this work. The masts are modeled as vertically supported cantilever beams,with one end fixed to the ground, and the other end free. The external excitation forces acting of the masts are the results of vortex shedding represented by a sinusoidal time dependent functions. The frequencies of these sinusoidal functions are dictated by the Strouhal numbers associated of the flow regimes crossing over the masts. To enhance the vibratory behavior of a typical mast, under the influence of flow induced vibrations,three different mass distributions along the length …
Dynamic Analysis Of A Rotor Bearing System, Sandi Elhibir
Dynamic Analysis Of A Rotor Bearing System, Sandi Elhibir
ETD Archive
This thesis presents the results of the finite element analysis (FEA) approach for designing a Permanent Magnet Alternator (PMA). The PMA is configured as a cantilever hollow shaft supported by two identical rolling contact bearings. The performance requirements of the PMA are a maximum operating speed of 16,000 rpm, with a maximum shaft displacement of less than 0.010 in at its free end. The static and dynamic results of a cantilever beam was predicted by closed form solutions and verified to those results obtained from FEA for code validation. A mathematical model of a rotor-bearing system was proposed and analyzed …
Non-Collocation Problems In Dynamics And Control Of Mechanical Systems, Timothy M. Obrzut
Non-Collocation Problems In Dynamics And Control Of Mechanical Systems, Timothy M. Obrzut
ETD Archive
Characteristics of mechanical systems with non-collocated sensors and actuators are investigated. Transfer function zeros location as a function of sensor position, zero-pole interlacing, and re-location of zeros are discussed in a context of presented examples. Some of the presented examples involving non-collocation are supported by experimental data. A case study involving a high speed machining spindle is examined. The control problems associated with non-collocation are studied along with the methods to solve them
Smart Rotating Machines For Structural Health Monitoring, Dmitry Leonidovich Storozhev
Smart Rotating Machines For Structural Health Monitoring, Dmitry Leonidovich Storozhev
ETD Archive
The objective of this thesis is to explore an innovative approach to the on-line health monitoring of rotating machinery in the presence of structural damage using active magnetic bearings (AMBs). First, the detailed model of the rotor with the breathing transverse crack is developed using finite element method. Next, the experimental data from the rotating magnetically levitated healthy and cracked shafts, under specially designed external excitation force, was collected, analyzed and compared with the computer simulation. The obtained results demonstrate that the presented on-line health monitoring technique is very effective for detection of the structural damage in rotating machinery, and …
Slurry Based Coatings On Silicon Based Ceramics, Muralidhar Challarapu
Slurry Based Coatings On Silicon Based Ceramics, Muralidhar Challarapu
ETD Archive
Silicon carbide/silicon carbide (SiC/SiC) composites are the leading candidates for advanced high temperature structural components in gas turbine engine application. When SiC surface reacts with O2, protective SiO2 scales are formed, which are the basis for the corrosion resistance of SiC. Their main draw back in terms of usage in a gas-turbine engine is the volatilization of the protective silica scale because of the water vapor which is a byproduct of fuel combustion. The purpose of this project was to develop environmental barrier coatings (EBCs) based on ceramic powders to provide resistance to such moisture damage. In this thesis slurry-coating …