Engineering Commons^™

The Structure And Ferroelectric Properties Of Iron-Doped Lead Titanate, Michael Bartlein

Theses and Dissertations

Multiferroics are a class of poorly understood, but technologically important materials. Lead(II) titanate (PbTiO$_3$) is a known perovskite ferroelectric. By doping PbTiO$_3$ with Fe$^{3+}$ at the Ti site, we produce the multiferroic PbTi$_{1-x}$Fe$_x$O$_3$ (PTFO). Using selected area electron diffraction on a transmission electron microscope, the structure of PTFO is investigated. Of particular interest is identifying the cubic-to-tetragonal transition at the Curie temperature. As the concentration of Fe increases, the crystal becomes more cubic and experiences a lower transition temperature. I also establish a procedure for preparing bulk PTFO samples for ferroelectric testing and present preliminary results establishing ferroelectricity in these …

Biomechanical Joint Demands And Functional Outcomes During Manual Wheelchair Use In Pediatric Patients With Spinal Cord Injury, Christine M. Aurit

Theses and Dissertations

The biomechanical demands of the upper extremities (UEs) during pediatric manual wheelchair (MWC) use have not been fully explored. Children who use MWCs for mobility engage in a range of functional activities that may place large biomechanical demands on the UEs leading to a high risk on overuse injuries. This study aims to analyze the kinematics and kinetics of pediatric manual wheelchair use during propulsion, starting, stopping and weight relief tasks. Fourteen pediatric patients with spinal cord injury were recruited and data were collected using a 14-camera Vicon MX motion analysis system (Oxford Metric Group, Oxford, UK) and a SmartWheel …

Mechanical Properties Of Glass Fiber Reinforced Polymer Bars After Exposure To Elevated Temperatures, Mohammed Abdulqader Jalil Alsalihi

Theses and Dissertations

ABSTRACT

MECHANICAL PROPERTIES OF GLASS FIBER REINFORCED POLYMER BARS AFTER EXPOSURE TO ELEVATED TEMPERATURES

by

Mohammed A. J. Alsalihi

The University of Wisconsin-Milwaukee, 2014

Under the Supervision of Professor Habib Tabatabai

In the past few decades, the use of composite materials has become more widespread in different fields and industries. Part of this increase comes as an answer to the corrosion issues that ordinary steel faces. Fiber Reinforced Polymers (FRP)s offer a number of advantages that make them an adequate solution to challenges in the rapidly developing construction industry. However, the behaviors of these materials at elevated temperatures and their …

An Optogenetic Brain-Machine Interface For Spatiotemporal Neuromodulation, Ryan Andrew Baumgartner

Theses and Dissertations

Direct neural stimulation has recently become a standard therapy for neurological disorders such as Parkinson's Disease, Essential Tremors, and Dystonia. Currently, deep brain electro-stimulation and neuro-pharmaceutical treatments are the dominant therapeutic options available to the public. As our understanding of brain function and neurological diseases improves, we are able to develop more advanced neuromodulation techniques. These methods could become viable treatment solutions for treating brain dysfunction. Optogenetics, first introduced by a research team led by Karl Deisseroth at Stanford University, has proved to be a versatile technique with remarkable potential to be used in treatments for brain disorders, dysfunction, and …

Improving Mri Surface Coil Decoupling To Reduce B1 Distortion, Christian K. Larson

Theses and Dissertations

As clinical MRI systems continue to advance, larger focus is being given to image

uniformity. Good image uniformity begins with generating uniform magnetic fields, which

are easily distorted by induced currents on receive-only surface coils. It has become an

industry standard to combat these induced currents by placing RF blocking networks on

surface coils. This paper explores the effect of blocking network impedance of phased array surface coils on B1 distortion. It has been found and verified, that traditional approaches for blocking network design in complex phased arrays can leave undesirable B1 distortions at 3 Tesla. The traditional approach of …

On The Nonlinear Tribological Jerk Dynamics At Sliding Interfaces, Divyeshkumar Patel

Theses and Dissertations

As the world desires the next industrial revolution, the potential threats that will undermine energy efficient innovations include detrimental frictional effects that exacerbate wear, hasten equipment breakdowns, and worsen heat dissipation. Capturing the inherently nonlinear manifestations of friction fundamentally has been difficult. A fundamental modeling scheme elucidating friction will bolster novel technologies synthesizing wear resistant materials and lubricants needed for sustainable energy efficiency.

Frictional dissipation at dynamical sliding interfaces has been studied for generations. Interfacial sliding frictional effects are prevalent in natural and artificial phenomena such as earthquake, hip and knee joints, and the moving parts of energy-producing and energy-consuming …

A Novel Transport Based Model For Wire Media And Its Application To Scattering Problems, Ebrahim Forati

Theses and Dissertations

Artificially engineered materials, known as metamaterials, have attracted the interest of researchers because of the potential for novel applications. Effective modeling of metamaterials is a crucial step for analyzing and synthesizing devices. In this thesis, we focus on wire medium (both isotropic and uniaxial) and validate a novel transport based model for them.

Scattering problems involving wire media are computationally intensive due to the spatially dispersive nature of homogenized wire media. However, it will be shown that using the new model to solve scattering problems can simplify the calculations a great deal.

For scattering problems, an integro-differential equation based on …

Speech Perception In Reverberated Condition By Cochlear Implants, Moulesh Bhandary

Theses and Dissertations

Previous Studies for bilateral cochlear implants users examined cocktail -party setting under anechoic listening conditions. However in real world listeners always encounter problems of reverberation, which could significantly deteriorate speech intelligibility for all listeners, independent of their hearing status.

The object of this study is to investigate the effects of reverberation on the binaural benefits for speech recognition by bilateral cochlear-implant (CI) listeners.

Bilateral CI subject was tested under different reverberation conditions. IEEE recorded sentences from one male speaker mixed with either speech shaped noise (ssn), energy masking, or with 2 female competing takers (2fsn), informational masking, at different signal …

Evaluation And Forecast Of Energy Consumption In Different Sectors Of The United States Using Artificial Neural Networks, Arash Kialashaki

Theses and Dissertations

The United States is a country which consumes a vast amount of energy. In order to keep the development of the United States sustainable (diverse and productive over the time) energy planning should be carried out comprehensively and precisely. This dissertation presents a specific mathematical modeling approach towards energy demand modeling of the United States and forecast future energy demand. To generate more detailed and accurate results, this dissertation investigates the energy demand of each sector separately using the analysis of trend for unique set of independent parameters which affect the energy demand in that sector.

In solving a forecast …

The Effects Of A Selected Wheel Design And Caster Fixture Design On Pushing Force When Pushing Four Wheeled Industrial Carts, David Wein

Theses and Dissertations

Manual material handlings tasks, many of which require pushing and pulling are common in almost all industrial and service sector environments. These tasks expose workers to musculoskeletal stresses as well as other related slipping and tripping hazards. The company sponsor of this study sought to lower the risk of injury from manually pushing and pulling carts. The company wanted to evaluate a newer style of split wheel and also an offset pivot dual orbital caster, which the manufacturer states will reduce pushing and pulling force. A total of eight participants (4 male, 4 female) were included in the study. Participants …

Primary Creep In Astm A325 Bolts Under Simulated Fire Loading, Mohammad Matar

Theses and Dissertations

At room temperature, small creep effects are present on steel structures. This is not the case at fire condition where the temperature is much higher than room temperature; in this case creep can be significant, and should be taken into consideration. Since fire hazard can happen in any building, creep effect must be taken into consideration when designing a building. Creep strain behaves as a function of time, temperature and stress. As the temperature increases, the creep strain increases. Similarly, the longer the temperature at a given stress on the structure, the more the creep strain present.

The smallest component …

Role Of Sensation In Altered Phalanx Grip Force In Persons With Stroke, Leah R. Enders

Theses and Dissertations

Many individuals experience hand impairment after stroke leading to decreased ability to perform daily living activities. Previous research studies have investigated how stroke survivors' pinch grip control differs from healthy individuals, even though many individuals can only grasp with power grip after stroke. Furthermore, many stroke survivors experience tactile sensory deficit in their paretic limb in addition to motor deficit. It is currently unknown how stroke induced tactile sensory deficit affects power grip force directional control, which is important in terms of preventing object slippage and power grip normal force generation. Additionally it is unknown if power grip could be …

Carbon Dioxide Photoreduction With Water Vapor By Titanium-Containing Magnesium-Aluminum Layered Double Hydroxides, Jinye Xu

Theses and Dissertations

Photocatalytic conversion of CO2 into value-added solar fuels is a promising approach to simultaneously address the greenhouse gas pollution and energy shortage issues. TiO2, the most widely studied photocatalyst, suffers from drawbacks like fast electron-hole recombination and limited CO2 adsorption. In this study, Ti-containing MgAl layered double hydroxides (MgAl/Ti-LDHs) were designed to provide high activity of CO2 photoreduction by dispersing Ti species over MgAl-LDHs which have been extensively investigated as CO2 adsorbent. This study was the first attempt to apply MgAl/Ti-LDHs for photoreduction of CO2 with water vapor.

MgAl/Ti-LDHs were prepared through coprecipitation (CP) method, the most common technique for …

Novel Nanostructured Materials For Solar Fuel Production And Advanced Rechargeable Batteries, Cunyu Zhao

Theses and Dissertations

Non-renewable fossil fuels are the major sources to meet the energy, electricity and transportation demands of today's world. The over consumption of fossil fuels will lead to the increasing energy crisis and disastrous effects such as air pollution, global warming etc.

The primary greenhouse gas is CO2 mainly emits from the combustion of fossil fuels. Photocatalytic reduction of CO2 using sunlight as the energy input is a promising way to reduce CO2 level in the atmosphere and in the meantime produce alternative fuels such as CO, methane, methanol, etc. Among the various photocatalyst materials reported, nanomaterial TiO2 is the most …

Cryoimaging-Microscopy Implementation For 3d Optical Imaging, Mohammad Masoudimotlagh

Theses and Dissertations

The structures and biochemistry properties of biological tissues are mostly affected by diseases. The visualization of organ structure and biochemistry helps in early detection and progression monitoring of diseases.

Although, 2D imaging has traditionally been used to gain information from the tissue, it does not accurately represent many of the structures and functions. There currently exists a need for sensitive and specific methods to show detailed information about the structure of the tissue with high resolution and in 3D. The potential advantage of the high resolution 3D images is the ability to accurately probe structural and biochemical properties of the …

Development And Usability Evaluation Of Low-Cost Virtual Reality Rehabilitation Games For Patients With Upper Limb Impairment, Jayashree Arunkumar

Theses and Dissertations

Stroke is one of the primary causes of long-term disability in adults in the United States which leads to mild to severe sensorimotor impairments. Long-term continuous rehabilitation therapies are needed to facilitate sensorimotor recovery and empower patients in performing daily living activities. Currently, the opportunity of receiving post stroke rehabilitation in the chronic stage (> 6 months post stroke) is limited due to a lack of insurance and the high cost of therapy. Low-cost virtual rehabilitation games with motion tracking devices have tremendous potential to assist physical rehabilitation. Motion tracking devices such as Kinect (Microsoft, Redmond, CA; $100) and P5 …

Molecular Dynamics (Md) Study On The Electrochemical Properties Of Electrolytes In Lithium-Ion Battery (Lib) Applications, Negin Salami

Theses and Dissertations

While the high energy density and the power along with longer cycle life and less requirements of maintenance distinguish the rechargeable lithium-ion batteries (LIBs) from other energy storage devices, development of an electrolyte of LIBs with optimized properties still constitutes a challenge towards next-generation LIB systems with robust electrochemical performance. The electrolytes serve as the medium to provide ionic conduction path between the electrodes as their basic function. Conductivity of the solutions are mainly affected by their transport properties and the electrolyte electrode/separator interfacial phenomena. Although many contributions on thermodynamic properties of the electrolytes consist of alkyl carbonates mixed with …

A Decision Support System To Analyze, Predict, And Evaluate Solar Energy System Performance: Pvsysco (Photovoltaic System Comparison), Lisa Bosman

Theses and Dissertations

In 2010, the U.S. Department of Energy announced the SunShot Initiative, which aims to reduce the total installation cost of solar technologies by 75% between 2010 and 2020. This implies that solar energy is a top priority in the U.S. and many other countries. The purpose of this dissertation research is focused on creating a model to better understand the performance and reliability of photovoltaic (PV) energy systems over time. The model will be used to analyze, predict, and evaluate the performance of PV systems, taking into consideration technological and geographical location attributes. The overall research goal is to build …

Effect Of Junction Geometry On Monodispersed Microdroplet Generation In Microfluidic Aqueous Two-Phase Systems, Young Gyu Nam

Theses and Dissertations

Aqueous two-phase system (ATPS) consists of two immiscible water-based solutions of polymers, which can form phase partitioning. Dextran and polyethylene glycol I used in this thesis is the one of common components of aqueous two-phase system give a reliable and incompatible environment for purification of biomedical products and cellular macromolecules. Recently, ATPS have received increasing attention as a separation method in microfluidic device due to the advantages of biocompatibility, unlimited combination, and low interfacial tension. Hence, it became an important to discover researches related to ATPS microfluidic device.

Microdroplets produced in microfluidic device are a largely interesting phenomenon for various …

Novel Substrate-Bound Hybrid Nanomaterials For Anode Electrodes In Lithium-Ion Batteries, Haejune Kim

Theses and Dissertations

Li-ion batteries (LIBs) are commercially dominant in electrochemical energy storage devices. Their wide applications as power sources, from portable electronics to electric vehicles/hybrid electric vehicles, are mainly attributed to their superior energy density based on unit volume and unit weight over other battery systems. Growing demands for lighter, longer-lasting, and more powerful devices spur the development of new electrode materials, because the performance of LIBs is highly dependent on the characteristics of electrodes. The ideal candidate for anode materials of LIBs should have high lithium storage capability and stable structure after repeated charge/discharge cycles. Since its first commercialization by Sony …

Optimal Dc Power Distribution System Design For Data Center With Efficiency Improvement, Xuechao Wang

Theses and Dissertations

Data Center Power Distribution design is very popular today focusing on improved energy efficiency and reduced operating cost. Conventionally data centers use low efficiency electrical power distribution systems with large AC power transformers, high power losses, and AC UPS and PDU power conversions. Most IT servers utilize low voltage level (12V or 48V) as the power source, which requires a step-down transformer and AC to DC rectifiers in every PDU. The "Proposed 380V DC Power Distribution System" promises to deliver high transmission efficiency and low power component cost.

This is a comprehensive design including data center physical architecture and equipment …

Experimental, Numerical And Analytical Characterization Of Torsional Disk Coupling Systems, Alex B. Francis

Theses and Dissertations

Torsional couplings are used to transmit power between rotating components in various power systems while allowing for small amounts of misalignment that may otherwise lead to equipment failure. When selecting a proper coupling type and size, one has to consider three important conditions: (1) the maximum load applied to the coupling, (2) the maximum operation speed, and (3) the amount of misalignment allowable for normal operation. There are many types of flexible couplings that use various materials for the flexible element of the coupling. The design of the coupling and the materials used for the flexible portion will determine its …

Air-Gap Partial Discharge Development Stage Recognition For Power Transformer Insulation Monitoring Considering Effect Of Cavity Size, Zhenze Long

Theses and Dissertations

Oil-paper insulation system is commonly used for power transformer internal insulation. Partial discharge (PD) is one of the main reasons for aging and disruption of the insulation system. Air-gap PD occurs in gas-filled cavity in transformer oil-paper insulation and is an extremely common and serious defect type. For air-gap PD analysis, most experiments were conducted through the standard air-gap discharge model recommended by CIGRE. Some work has been done to diagnose air-gap PD severity. However, the effect of cavity size on PD activity has not been emphasized yet. My thesis systematically discusses the effect of cavity size on air-gap PD …

Coupled Electromagnetic And Thermal Analysis And Design Optimization Of Synchronous Electric Machines, Yi Wang

Theses and Dissertations

A new technique for coupling the electromagnetic, thermal, and air-flow analysis is proposed for electronically controlled synchronous machines. A computationally efficient finite element analysis (CE-FEA) technique is employed for the electromagnetic field analysis. An equivalent circuit network is used for thermal and air-flow analysis. An iterative algorithm, which exploits the fact that the type of machines studied have very low rotor losses and also a relatively reduced dependency of core losses with temperature and load, has been developed. The overall computational time is significantly reduced in comparison with the conventional coupling method, such that the new technique is highly suitable …

Short-Term Forecasting Of Wind Speed And Wind Power Based On Bp And Adaboost_Bp, Sibei Mi

Theses and Dissertations

Due to wind is intermittent and less dispatchable, wind power fluctuates as the wind fluctuating and is uncontrollable. Therefore, when wind power accounts for a higher proportion of total electricity generation of the system, power generation plan needs to arrange according to the variation of wind power output. The way to solve the problem is forecasting the wind power.

In this paper, we focus on the wind speed and wind power forecasting in the time scales of 10min, 1h and 3h in the future. BP Neural Network and Adaboost_BP Neural Network are selected as the forecasting model for wind speed …

A Study Of The Development Of An Analytical Wall Function For Large Eddy Simulation Of Turbulent Channel And Rectangular Duct Flow, Takahiko Hasegawa

Theses and Dissertations

This paper reports computational work of three-dimensional channel turbulent flow and rectangular duct flow with the Analytical Wall Function (AWF). The main purpose of this study is to establish and validate the new modeling of AWF for Large Eddy Simulation (LES-AWF). In order to compare the performance of the new modeling of LES-AWF, the conventional LES-AWF and Wall-resolved LES are applied. The new LES-AWF showed improvements of flow prediction in both of three-dimensional channel flow and rectangular duct flow, although the improvement in rectangular duct is relatively minor.

Optimizing The Synchronization Of Multiple Bus Routes At Multiple Transfer Points Assuming Stochastic Bus Journey Times, Jirapa Sorussa

Theses and Dissertations

In this thesis, we develop a discrete event simulation model of a generic bus transit system in which transfers of passengers between bus routes are considered at all bus stops in the network. The model considers several real-world aspects including stochastic passenger demand and stochastic bus travel times. Transfers of individual passengers between bus routes are explicitly modeled. The model shows how different values for the decision variables - the route assigned to each bus and the timetable for each bus - affect the time an average passenger spends in the system and other performance measures. In the experiments, we …

Production Scheduling In Integrated Steel Manufacturing, Wanxi Li

Theses and Dissertations

Steel manufacturing is both energy and capital intensive, and it includes multiple production stages, such as iron-making, steelmaking, and rolling. This dissertation investigates the order schedule coordination problem in a multi-stage manufacturing context. A mixed-integer linear programming model is proposed to generate operational (up to the minute) schedules for the steelmaking and rolling stages simultaneously. The proposed multi-stage scheduling model in integrated steel manufacturing can provide a broader view of the cost impact on the individual stages. It also extends the current order scheduling literature in steel manufacturing from a single-stage focus to the coordinated multi-stage focus. Experiments are introduced …

Propagation Of An Optical Vortex In Fiber Arrays With Triangular Lattices, Muhammad Abdulrahman Mushref

Theses and Dissertations

The propagation of optical vortices (OVs) in linear and nonlinear media is an important field of research in science and engineering. The most important goal is to explore the properties of guiding dynamics for potential applications such as sensing, all-optical switching, frequency mixing and modulation. In this dissertation, we present analytical methods and numerical techniques to investigate the propagation of an optical vortex in fiber array waveguides. Analytically, we model wave propagation in a waveguide by coupled mode Equations as a simplified approximation. The beam propagation method (BPM) is also employed to numerically solve the paraxial wave Equation by finite …

Thermal Cooling Effects In The Microstructure And Properties Of Cast Cobalt-Base Biomedical Alloys, Vladimir Vega Valer

Theses and Dissertations

Joint replacement prosthesis is widely used in the biomedical field to provide a solution for dysfunctional human body joints. The demand for orthopedic knee and hip implants motivate scientists and manufacturers to develop novel materials or to increase the life of service and efficiency of current materials. Cobalt-base alloys have been investigated by various researchers for biomedical implantations. When these alloys contain Chromium, Molybdenum, and Carbon, they exhibit good tribological and mechanical properties, as well as excellent biocompatibility and corrosion resistance.

In this study, the microstructure of cast Co-Cr-Mo-C alloy is purposely modified by inducing rapid solidification through fusion welding …