Mechanical Engineering Commons^™

Dynamic Responses Of Wheel-Rail Systems With Block Dampers, Tzuyu Tseng

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The wheel-rail interaction problem has been widely studied in the past few decades. In this problem, dynamic responses at the contact areas remain the central issue since they induce damage to the rail over time. In particular, the dynamic responses at the contact areas between the wheels and rails present difficulties in understanding and mathematical modeling. Even with the computer power one has today, its mathematical modeling employs the versatile numerical analysis method, the finite element method (FEM) remains a formidable challenge due to its extremely small contact areas and in turn the extremely high stress levels. In addition, friction …

The Feasibility Of Using A Markerless Motion Capture Sensor (Leap MotionTm Controller) Forquantitative Motor Assessment Intended For A Clinical Setting, Clay Jordan Kincaid

Theses and Dissertations

Although upper limb motor impairments are common, the primary tools for assessing and tracking these impairments in a clinical setting are subjective, qualitative rating scales that lack resolution and repeatability. Markerless motion capture technology has the potential to greatly improve clinical assessment by providing quick, low-cost, and accurate tools to objectively quantify motor deficits. Here we lay some of the groundwork necessary to enable markerless motion capture systems to be used in clinical settings. First, we adapted five motor tests common in clinical assessments so they can be administered via markerless motion capture. We implemented these modified tests using a …

A Study To Develop An Electronics Chassis Compound Cylinder Pressure Vessel Using Finite Element Modeling, Gordon Randall Straley

Theses and Dissertations

This thesis develops a process to design and analyze a two-layer compound cylinder pressure vessel utilizing an inner insert to house electronic circuit card assemblies. The process begins with sizing and analysis of a compound cylinder based on analytical formulas and progresses in complexity to a 2-Dimensional plane stress finite element model of the chassis assembly and ends with a computationally expensive 3-Dimensional finite element analysis of the pressure vessel. Comparing the results from the compound cylinder to the electronics chassis, it is observed that the inner insert geometry has a strong influence on the interfacial pressure at the upper …

Numerical Study Of Erosion Of The Internal Wall Of Sales Gas Piping By Black Powder Particles, Ahmed Saud Al-Haidari

Theses and Dissertations

Micro particles, primarily from iron, can wreak havoc on a Sales Gas System. For example, the transport of particles with the gas flow can cause erosion damage to the piping system, lead to the release of toxic gasses, and interrupt the operation. The objective of the current work is to examine the erosion rate (ER) in an existing Sales Gas Piping System by simulating different black powder particles sizes and considering variable operation conditions. An elbow-shaped pipe spool is used to determine the area of maximum destruction. It will help the designer, engineer and operation personnel to predict the ER …

Design For Manufacturability And Assembly Of An Assistive Technician Creeper, Including Single Drive Control Of A Multi-Degree Of Freedom Kinematic Mechanism, Larry T. Wilde Jr.

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In 2011, a team of engineering students at Utah State University designed and built an assistive technician creeper to assist persons with lower-extremity physical disabilities to work in low-clearance areas. In order to put this technology on the market, a complete product redesign was needed to address safety and functionality concerns. This thesis outlines the specific design needs, presents the detailed design approach, and summarizes the final creeper solution. The mechanisms of the initial prototype were modified to independently incline or recline the upper body, and raise or lower the seat surface with a single motor. This will be especially …

Best Practices For Volume Flow Rate Measurements Using Piv At The Exit Of A Turbulent Planar Jet, Rick Cressall

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Particle image velocimetry (PIV) is used to make volume-flow-rate measurements at the exit of a turbulent, planar nozzle. The objective of this report is to assess a range of data acquisition and processing parameters. Data is acquired for volume flow rates of Reynolds numbers between 10,000 and 100,000 for both two-component (2C) and stereo PIV. The parameters are systematically changed one at a time and evaluated using differences in uncertainty, calculation time, and volume- flow-rate deviation. Data acquisition parameters follow the trends of previous work. A multitude of processing parameters were varied for several PIV processing methods. Recommendations for each …

Integrated Design Of Downwind Land-Based Wind Turbines Using Analytic Gradients, Andrew Ning, Derek Petch

Faculty Publications

Wind turbines are complex systems where component-level changes can have significant system-level effects. Effective wind turbine optimization generally requires an integrated analysis approach with a large number of design variables. Optimizing across large variable sets is orders of magnitude more efficient with gradient-based methods as compared to gradient-free method, particularly when using exact gradients. We have developed a wind turbine analysis set of over 100 components where 90% of the models provide numerically exact gradients through symbolic differentiation, automatic differentiation, and adjoint methods. This framework is applied to a specific design study focused on downwind land-based wind turbines.

Downwind machines …

Implementation And Performance Evaluation Of Acoustic Denoising Algorithms For Uav, Ahmed Sony Kamal Chowdhury

UNLV Theses, Dissertations, Professional Papers, and Capstones

Unmanned Aerial Vehicles (UAVs) have become popular alternative for wildlife monitoring and border surveillance applications. Elimination of the UAV’s background noise and classifying the target audio signal effectively are still a major challenge. The main goal of this thesis is to remove UAV’s background noise by means of acoustic denoising techniques. Existing denoising algorithms, such as Adaptive Least Mean Square (LMS), Wavelet Denoising, Time-Frequency Block Thresholding, and Wiener Filter, were implemented and their performance evaluated. The denoising algorithms were evaluated for average Signal to Noise Ratio (SNR), Segmental SNR (SSNR), Log Likelihood Ratio (LLR), and Log Spectral Distance (LSD) metrics. …

An Emg-Based Patient Monitoring System Using Zynq Soc Device, Farhad Fallahlalehzari

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis describes the design, development, and testing of an EMG-based patient monitoring system using the Zynq device. Zynq is a system on chip device designed by Xilinx which consists of an ARM dual cortex-A9 processor as well as an FPGA integrated into one chip. This work also analyzes the performance of image-processing algorithms on this system and compares that performance to more traditional PC-based systems. Image processing algorithms, such as Sobel edge detection, dilation and erosion, could be used in conjunction with a camera for the patient monitoring purposes. These algorithms often perform sub-optimally on processors because of their …

Radiation Therapy And Dosing Material Transport Methodology, Robert O'Brien

UNLV Theses, Dissertations, Professional Papers, and Capstones

A technique is examined here that utilizes high energy beta decays from a short lived radioisotope to treat medical conditions such as shallow cancerous lesions. A major benefit of beta particle interaction in tissue is a fixed penetration depth for the charged particle, with dose limited to the ultimate range of the beta particle. This method improves on some current techniques of radioactive brachytherapy, where "seeds" are placed inside patients through temporary or permanent implantation in order to kill cancerous cells or inhibit growth of tissue. The use of low energy gamma-rays is the most common method of treatment currently …

Ionic Electroactive Polymer Devices: Physics-Based Modeling With Experimental Investigation And Verification, Tyler Paul Stalbaum

UNLV Theses, Dissertations, Professional Papers, and Capstones

The primary focus of this study is to examine, understand, and model ionic electroactive polymer based systems in attempt to further develop this field of study. Physics-based modeling is utilized, as opposed to empirical modeling, to achieve a deeper insight to the underlying physics. The ionic electroactive polymer system of primary interest in this study is ionic polymer-metal composite (IPMC) devices. Other similar devices, such as anion-exchange membrane (AEM) type actuators and flow battery systems are also investigated using the developed model. The underlying physics are in the studies of transport phenomenon for describing the ionic flow within the polymer …

The Effects Of Cryopreservation On Human Dental Pulp-Derived Mesenchymal Stem Cells, Allison Elaine Tomlin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many studies have demonstrated clinical applications for the use of dental pulp stem cells (DPSC) for the treatment of various conditions. This has driven medical and scientific interest in the collection, isolation and banking of DPSC tissues for research into these potential therapies. Few studies to date have evaluated the viability of DPSC following long-term cryopreservation. The purpose of this study is to evaluate the effects of cryopreservation on dental pulp-derived stem cells (DPSC) viability over a period of three years. Dental pulp-derived stem cells were isolated and cultured from thirty-one healthy teeth. DPSC isolates were assessed for doubling-time and …

Stationary Nonimaging Concentrators – A Comprehensive Study And Design Improvements, Srikanth Madala

UNLV Theses, Dissertations, Professional Papers, and Capstones

Most places on our planet receive an annual average radiation between 800-1000 W/m2. In the man-made world, this radiation is largely incident on stationary structures such as buildings, roads, monuments, bridges etc. Moreover, in the natural world also, there are large tracts of barren land which can be put to good use given their solar energy potential. The vision of the current research is to concentrate all this available solar energy to a more readily usable form. Therefore, stationary nonimaging solar concentrator technologies are sought after. This dissertation work is an exhaustive research on the nonimaging concentrating mechanisms with stationary …

Effect Of Ducted Hpwh On Space-Conditioning And Water Heating Energy Use - Central Florida Lab Home, Florida Solar Energy Center, Carlos Colon

FSEC Energy Research Center®

The purpose of this research is to investigate the impact of ducted heat pump water heaters (HPWHs) on space-conditioning and water heating energy use in residential applications. Two identical HPWHs, each with a capacity of 60 gal, were tested side by side at the Flexible Residential Test Facility (FRTF) laboratories on the Florida Solar Energy Center (FSEC) campus in Cocoa, Florida. The FRTF's residential buildings feature the same square footage (1,535 ft2 ), orientation, and envelope characteristics; currently, the only difference between them is the finished floor material. The east FRTF building is furnished with standard carpet flooring, whereas the …

Focused-Based Multifractal Analysis Of The Wake In A Wind Turbine Array Utilizing Proper Orthogonal Decomposition, Naseem Ali, Hawwa Falih Kadum, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Hot-wire anemometry measurements have been performed in a 3×3 wind turbine array to study the multifractality of the turbulent kinetic energy dissipation. A multifractal spectrum and Hurst exponents are determined at nine locations downstream of the hub height, bottom and top tips. Higher multifractality is found at 0.5D and 1D downstream of the bottom tip and hub height. The second order of the Hurst exponent and combination factor shows the ability to predict the flow state in terms of its development. Snapshot proper orthogonal decomposition (POD) is used to identify the coherent and incoherent structures and to reconstruct the stochastic …

Determination Of Aqueous Surfactant Solution Surface Tensions With A Surface Tensiometer, Remelisa Esteves, Birce Dikici Ph.D, Matthew Lehman, Qayyum Mazumder, Nonso Onukwuba

Beyond: Undergraduate Research Journal

Surfactant solutions are applicable to engineering systems for cooling equipment for electronics. Surfactants can be added to water to improve heat transfer. An application of using aqueous surfactant solutions can be through microchannel heat sink. Although it is ideal to redesign these systems to reduce heat, it is a costly method. Surfactant solutions at optimal solution concentration can be able to transfer heat quickly and effectively with minimum expense. The surface tension of surfactant solutions is an important parameter for boiling heat transfer and must be taken into consideration. The purpose of this research is to measure surface tension of …

Determination Of Surfactant Solution Viscosities With A Rotational Viscometer, Remelisa Esteves, Nonso Onukwuba, Birce Dikici Ph.D

Beyond: Undergraduate Research Journal

Aqueous surfactant solutions are used in engineering systems for improving boiling heat transfer. The purpose of this research is to determine the viscosities of surfactant solutions and to investigate the effect of composition on viscosity. The results obtained can possibly be used as reference for further study in the effects of surfactant solution viscosities on nucleate boiling. A rotational viscometer was used to determine the viscosities of three surfactant solutions – SLS, EH-14, and SA-9 – of various compositions at room temperature. It was discovered that the viscosities of SLS, EH-14, and SA-9 had a nearly consistent pattern as their …

Extracting Vibration Characteristics Of A Guitar Using Finite Element, Modal Analysis, And Digital Image Correlation Techniques, Kiran Patil, Javad Baqersad, Daniel Ludwigsen, Yaomin Dong

Physics Publications

The sound quality generated by the guitar depends on the vibration characteristics (i.e. natural frequencies and mode shapes) of this instrument. Thus, it is of particular interest to the guitar manufacturers to be able to obtain global information about the characteristics of the guitar. Traditional sensors can only measure at discrete locations. However, digital image correlation (DIC) can measure full-field data on the surface of the structure. In the current paper, a finite element (FE) model of a guitar with free boundary configurations was developed using quadratic solid elements. An eigensolution was performed on the FE model to determine its …

Evaluating Alternative Scheduling Rules To Improve Scheduling Performance, Bryan Allan White

Theses and Dissertations

In this study a powder painting production line was examined for the purpose of improving on its scheduling. A simulation model was developed to compare the performance of alternative scheduling rules. The simulation model utilized scheduling data from the original system in order to determine how accurately it represented the original system. The model was built using the discrete event simulation software Arena. The validated model was used to test a set of scheduling rules that would change the sequence in which orders in the queue were processed. By looking at the different rules and the effects on the final …

Loss-Induced Enhanced Transmission In Anisotropic Density-Near-Zero Acoustic Metamaterials, Chen Shen, Yun Jing

Henry M. Rowan College of Engineering Departmental Research

Anisotropic density-near-zero (ADNZ) acoustic metamaterials are investigated theoretically and numerically in this paper and are shown to exhibit extraordinary transmission enhancement when material loss is induced. The enhanced transmission is due to the enhanced propagating and evanescent wave modes inside the ADNZ medium thanks to the interplay of near-zero density, material loss, and high wave impedance matching in the propagation direction. The equi-frequency contour (EFC) is used to reveal whether the propagating wave mode is allowed in ADNZ metamaterials. Numerical simulations based on plate-type acoustic metamaterials with different material losses were performed to demonstrate collimation and subwavelength imaging enabled by …

Investigation Of Jet Dynamics In Cross-Flow: Quantifying Volcanic Plume Behavior, Graham Freedland

Dissertations and Theses

Volcanic eruption columns inject high concentrations of ash into the atmosphere. Some of this ash is carried downwind forming ash clouds in the atmosphere that are hazardous for private and commercial aviation. Current models rely on inputs such as plume height, duration, eruption rate, and meteorological wind fields. Eruption rate is estimated from plume height using relations that depend on the rate of air entrainment into the plume, which is not well quantified. A wind tunnel experiment has been designed to investigate these models by injecting a vertical air jet into a cross-flow. The ratio of the cross-flow and jet …

Single Site Robotc Device And Related Systems And Methods, Jack Mondry, Shane M. Farritor, Eric Markvicka, Thomas Frederick, Joseph Bartels

Department of Mechanical and Materials Engineering: Faculty Publications

The embodiments disclosed herein relate to various medical device components, including components that can be incor porated into robotic and/or in vivo medical devices. Certain embodiments include various medical devices for in vivo medical procedures.

Two-Phase Transport In Proton Exchange Membrane Fuel Cells, Kazuya Tajiri

TechTalks

In Multiscale Transport Process Laboratory our research is focused on the experimental and computational analysis of transport phenomena in electrochemical devices and propulsion systems. In this talk our research activity on proton exchange membrane fuel cells (PEMFCs) for automotive application will be explained. Water management is one of the most critical issues in PEMFCs. The water generated in catalyst layer as a product of the electrochemical reaction needs to be removed through porous media by diffusion if it’s vapor, or by capillarity in case of liquid. In flow channels, the liquid water is removed primarily by inertial force of the …

Solid State Sound: A "Hot" Topic, Andrew Barnard

TechTalks

As seen with the latest iPhone 7 release, traditional audio components can now be a limiting factor in technology design. What if we could make a loudspeaker with no moving parts and virtually no weight? Carbon nanotube loudspeakers are such devices. They create sound using heat oscillations, as opposed to a moving diaphragm. They have the thickness of only a handful of carbon atoms, are flexible and stretchable. In this TechTalk I’ll discuss the carbon nanotube loudspeaker and the design challenges in maturing this intriguing technology.

Wearable Electronics, Human-Centered Monitoring, Ye Sarah Sun

TechTalks

Non-contact solution in wearable electronics: A conventional clinical system requires the use of wet electrodes that are in contact with skin using conductive gel to acquire physiological signals. Those systems can acquire high quality signals but may not be feasible for a long-term purpose due to the skin irritation and allergic contact dermatitis. The emerging of human-centered monitoring calls for alternative solutions. Recent technological advances enable capacitive measurement that can acquire signals through cloth or even with an air gap in wearable condition. In this TechTalk I will introduce the non-contact solution in wearable electronics.

A Framework For Studying Meshfree Geometry And A Method For Explicit Boundary Determination, Joseph Bradley Alford

USF Tampa Graduate Theses and Dissertations

Patient-specific biomechanical analysis is an important tool used to understand the complex processes that occur in the body due to physical stimulation. Patient-specific models are generated by processing medical images; once an object from the image is identified via segmentation, a point cloud representation of the object is extracted. Generating an analysis suitable representation from the point cloud has traditionally required generating a finite element mesh, which often requires a well defined surface to accomplish. Point clouds lack a well defined geometry, meaning that the surface definition is incomplete at best. Point clouds that have been generated from images have …

Ev Workplace Charging Energy Use And Cost Case Study, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

Efforts to increase the availability of plug-in electric vehicle (PEV) charging stations have focused on expanding public charging stations, promoting charging at the workplace and using charging stations as a shopping incentive for retail stores. This report examines the costs and energy uses to provide the charging service. Rapidly charging a PEV requires expensive electric equipment and can lead to high operating costs due to electrical demand charges. This project presents results from a detailed case study for 5 PEV chargers where the charger electricity costs are a part of a facilities electric bill. Also presented are options for minimizing …

Material Selection Shape Factors For Compliant Arrays In Bending, David T. Fullwood, Todd G. Nelson, Jared T. Bruton, Nathan E. Rieske, M. Patrick Walton, Larry L. Howell

Faculty Publications

Similar to the general class of metamaterials, compliant arrays (CAs) are engineered from an array of subelements that combine to produce a response that is typically not available from a at panel made of a single material. As such, analysis and design of CA systems requires the integration of both the material and geometrical properties of the array. This paper proposes a convenient and efficient method of combining these essential elements using analytically derived shape factors for bending modes. The approach is validated experimentally, and used to demonstrate large regions of previously inaccessible property combinations in material selection charts that …

Mesh Addition Based On The Depth Image (Mabdi), Lucas E. Chavez

Mechanical Engineering ETDs

Many robotic applications utilize a detailed map of the world and the algorithm used to produce such a map must take into consideration real-world constraints such as computational and memory costs. Traditional mesh-based environmental mapping algorithms receive data from the sensor, create a mesh surface from the data, and then append the surface to a growing global mesh. These algorithms do not provide a computationally efficient mechanism for reducing redundancies in the global mesh. MABDI is able to leverage the knowledge contained in the global mesh to find the difference between what we expect our sensor to see and what …

Finite Element Simulation Of Pzt-Aided Interrogation Of Composite Laminates Exhibiting Damage, Amany Micheal, Yehia Bahei-El-Din

Centre for Advanced Materials

Piezoelectricity has proved effective in capturing changes in structures caused by various damage mechanisms. In one approach, piezoelectric wafer active sensors (PWAS) are mounted on the surface of the host structure and utilized as both actuators and sensors to interrogate the structure and monitor its health. This is achieved by subjecting the PWAS to a transient electric pulse and reading the resulting voltage. Changes in the stiffness of the substrate due to structural damage affect the response of the PWAS, which could be correlated to integrity of the structure. Applying this technique to fibrous composite laminates encounters particular challenges due …