Mechanical Engineering Commons^™

Investigation Of Relative Importance Of Some Error Sources In Particle Image Velocimetry, Jeff R. Harris

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Particle image velocimetry (PIV) is an optical technique used to measure fluid velocity. PIV measurements have many sources that create uncertainty in the velocity results. The objective of this report is to investigate some commonly cited uncertainty sources and to show methods than can be used to find the value of the uncertainty sources. These sources are: magnification, calibration, perspective, resolution and the computation scheme. Experiments were conducted to find the impact that sources have on the velocity measurements. Several methods are presented to demonstrate how to measure the uncertainty of error for a PIV experiment. Some error quantities are …

Effect Of Orifice Shape On Synthetic Jet Efficiency, David J. Nani

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

A synthetic jet is formed by periodic oscillation of a fluid through an orifice. The oscillatory motion is driven by diaphragm or other driver. Previous studies have demonstrated that synthetic jet formation and time-averaged cavity pressure are a function of the orifice shape. Traditionally, the performance of the jet is evaluated with varying configurations of fixed driver input voltage or fixed driver displacement. Neither of these measures accurately reflect the efficiency of the actuator. Defining efficiency as "desired output divided by required input," these traditional measures may not account for increase in required driving current or force.

A sharp inside …

In Situ Method Of Measuring Atmosphere Neutral Winds With A Rigid Falling Sphere, Joshua F. Martineau

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The new falling sphere instruments will measure lower E-region winds and density, which are critical for many of the electrodynamics and plasma physics studies that are carried out as part of the NASA suborbital rocket program. The new falling sphere design will take advantage of modern commercially available electronic components and materials. Of primary importance, it is proposed to fly an in-situ instrument that targets the measurement of neutral wind profiles over the altitude range from 80 to 150 km, with accuracy better than that achieved in previous implementations of the falling sphere technique and those typically obtained with the …

A Validation And Comparison About Vabs-Ide And Vabs-Gui, Teng Hu

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Variational Asymptotic Beam Section (VABS) analysis is a computer code for design and analysis of slender structure such as rotor blades, wind turbine blades, missiles, and rockets more efficiently than a full three-dimensional finite element analysis. VABS enables a rigorously a dimensional reduction of the original three-dimensional nonlinear analysis into a one-dimensional nonlinear beam analysis and a two-dimensional linear cross-sectional analysis. The VABS code has been extensively used in academia and industry for comput- ing the sectional properties and recovering three-dimensional fields of composite slender structures. Recently two graphic user interface, namely VABS-IDE and VABS-GUI, have been developed to automatic …

Shock And Vibration Isolation System For Ambulatory And Litter Patients In Ground And Air Medical Transport, Mohamad R. Hachem

UNLV Theses, Dissertations, Professional Papers, and Capstones

This project explored the effectiveness of seat and litter air bladder technologies in reducing patient exposure to whole body shock and vibration during ground borne and airborne medical transport. Several seat and litter air bladder configurations were examined during field tests in a U.S. Army RG-33 MRAP ambulance and a U.S. Army HH-60M Black Hawk helicopter. The MRAP field tests were conducted at Ft. Detrick, Maryland. The Black Hawk field tests were conducted at Ft. Rucker, Alabama.

During the field tests, tri-axial vibration signals were recorded on a 16-channel CoCo90 Data Logger/Frequency Analyzer and then post processed in the laboratory …

Using Stereo Particle Image Velocimetry To Quantify And Optimize Mixing In An Algae Raceway Using Delta Wings, Blake W. Lance

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Biofuel research has been continually growing over the past six decades. Of the potential sources for biofuels, microalgae is the most promising, and circulating (raceway) ponds are the most cost-effective method for growing microalgae in abundance. Nevertheless, biofuel production from algae must be more efficient to be competitive with traditional fuels. Previous studies using several airfoils, triangles, and squares at high angles to the flow direction (angle of attack) show an increase in mixing in raceways and can improve productivity by up to a factor of 2.2. Researchers show that increasing growth by increasing mixing is a repeatable effect that …

Simulation Of Counterintuitive Pressure Drop In A Parallel Flow Design For A Specimen Basket For Use In The Advanced Test Reactor, Adam X. Zabriskie

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To continue improving nuclear energy, new materials must be tested in testing reactors such as the Advanced Test Reactor (ATR) at Idaho National Laboratory. A new test cap section allowed coolant to contact specimens tested in the ATR. A parallel channel test cap section should reduce the pressure drop across this section compared to a single channel. A fluid experiment conducted by Idaho State University showed the pressure drop was actually greater. A Computation Fluid Dynamics simulation using STAR-CCM+ was conducted of the fluid experiment to explain the abnormal pressure drop. The simulation provided evidence of ow through the test …

Computational Fluid Dynamics Analysis Of Butterfly Valve Performance Factors, Adam Del Toro

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Butterfly valves are commonly used to control fluid flow inside of piping systems. A butterfly valve typically consists of a metal disc formed around a central shaft, which acts as its axis of rotation. As a butterfly valve is rotated open, fluid is able to more readily flow past the valve. A butterfly valve’s design is important to understand and is commonly characterized by its own performance factors. How a butterfly valve will perform, while in operation at different opening angles and under different types of flow, is critical information for individuals planning and installing piping systems involving the valve. …

Automated Assembly Time Prediction Tool Using Predefined Mates From Cad Assemblies, Joseph Owensby

All Theses

Current Design for Assembly (DFA) methods and tools require extensive amounts and types of user inputs to complete the analysis. Since the methods require extensive amounts and types of inputs, certain issues arise: the analysis can become tedious, time consuming, error prone, and not repeatable. These issues eventually lead to the DFA methods being used as a redesign tool or not being implemented at all.
The research presented in this thesis addresses the current DFA limitations and issues by developing and implementing an automated assembly time prediction tool that: extracts explicitly defined connections from SolidWorks assembly models, determines the structural …

Power Generation And Control Of Mechatronics Systems - Theory And Test, Kelly Austin

All Theses

An integrated, multi-disciplined approach to engineering design is a broad definition of mechatronics. Though some mechatronics proponents differ in their definitions of the topic, an interdisciplinary approach to engineering is taken by many industries which should be reflected on campus in the approach to engineering education. In this thesis, two mechatronics systems are investigated. A laboratory experiment is developed for use in the mechanical engineering program at Clemson University, and a thermoelectric power generation from diesel engine exhaust heat is investigated as an automotive industry application.
An electromagnet excited masspendulum system with attached spring and damper elements is introduced as …

Set Up Time Reduction And Quality Improvement On The Shop Floor Using Different Lean And Quality Tools, Seetha Ram Bavuluri

All Theses

The purpose of this thesis document is to describe a method developed for reducing setup time in machining processes and simultaneously improve the quality of production after setup. Bosch Rexroth at Fountain Inn is a semi-automated plant and is still in its initial stages of standardizing the setup process. Setup time at different machining centers includes: machining time, inspection time, loading and unloading times and deburring. The focus of the described method is in reducing setup times related to inspection time and loading and unloading times. To achieve success in these problems the following new tools were developed: first piece …

Charging Kinetics Of Micropores In Supercapacitors, Daniel Oberklein

All Theses

The charging kinetics of Electric Double Layer Capacitors (EDLC) were studied using a continuum model based on the Poisson-Nernst-Planck (PNP) Equations, with the additional modeling of the bulk fluid motion in the electrolyte using the Navier-Stokes Equations. The results demonstrate that the addition of bulk flow modeling yields a faster charging rate and higher charging current due to the additional convective component of the current resulting from the bulk fluid motion. A parametric study was conducted to determine the effect of various physical parameters of the EDLC system on the charging kinetics. Decreased fluid viscosity results in a faster charging …

Qualified Affordance-Based Design, Jun Hu

All Theses

Function-based approaches are taught by the engineering design community and implemented in practice. The most significant advantage of these approaches is that they can guide the designers to abstract the essential problems from the design requirements, build the function-based models, and consequently provide the direction of the solution. However, due to the lack of a consistent scientific definition on the meaning of the function, these approaches may be contradictory when representing human-centered aspects, features, and non-physical purposes. To address this issue, design researchers have pursued two general directions: (1) broadening the meaning of function and (2) introducing an alternative scientific …

A Case Study In Challenging And Validating Engineering Requirements With Value-Based Techniques, Seth Crouch

All Theses

Requirements are an essential element to engineering design as they are used to focus idea generation during conceptual design, provide criteria for decision making during concept selection, and verify the chosen concept fulfills product needs. Because they are essential to the entire design process, great emphasis needs to be put on ensuring that they are correct. This research focuses on a value-based methodology useful for challenging and validating established requirements. A case study was conducted using this process on a project involving the design of a vehicle seat. This case study shows that this approach provides more persuasive evidence to …

Assessment Of A Safe Driving Program For Novice Drivers And Smart Jersey Barrier Design To Minimize Animal-To-Vehicle Collisions, Lance Clark

All Theses

Each year, the total number of vehicles, motorists, highway infrastructures, and distance traveled by drivers increases on a global basis. This rise in personal and commercial ground vehicle usage brings with it the advantages of the modern age, but it is not without societal cost. Vehicular incidents result in tens of thousands of deaths each year in the United States alone. For this reason, research has been performed to advance driver safety while simultaneously providing wildlife with means to avoid animal-to-vehicle collisions (AVC). In this thesis, two solutions are proposed: a driver education program with classroom experiences, in-vehicle resources, and …

Applying Chaotic Advection To Rheology: An In Situ Structuring Rheometer, Ramaswami Subrahmanian

All Dissertations

A prototype In Situ Structuring Rheometer (ISSR) was designed and implemented to study changes in shear viscosity of polymer blends and composites while processing them in such a way as to control the evolution of microstructure. The ISSR is based on a regime of fluid mechanics known as chaotic advection, in which simple time-periodic flow fields can cause fluid particles to move chaotically. Chaotic advection is also the basis of Smart Blending, a technology employed to process polymer blends having a variety of morphologies at a fixed composition, and polymer composites in which the additives have been arranged into layered …

The Engineering Process For The Design Of A Motorcycle Chassis And Suspension, Derek J. Noce

Doctoral Dissertations and Master's Theses

The thesis objective is to define and establish an engineering process for the design of a modern motorcycle chassis and suspension. The engineering process focuses on the interdisciplinary fields of engineering dealing with design and structural optimization. Specialized software, such as Motorcycle Kinematics, MATLAB, CATIA, HEEDS Professional, and NASTRAN are utilized. Motorcycle Kinematics is used to set up the preliminary motorcycle geometry, and MATLAB is a used to analyze the kinematics and stability of the motorcycle based on this geometry. CATIA (Computer Aided Three-Dimensional Interactive Application) is used to graphically illustrate the geometry of the motorcycle in three dimensional space. …

Computational Representation And Reasoning Support For Requirements Change Management In Complex System Design, Beshoy Morkos

All Dissertations

Requirements play a critical role within any design process and the activity of identifying and maintaining a system's requirements is essential to. However, design is a complex and iterative process, where requirements are continuously evolving and are volatile. This change, if not managed, may result in undesired uncertainty within the design process leading to monetary losses and time delays, as the changing of requirements has been recognized as a major cause of project failure. In order to mitigate issues that arise due to requirement change propagation, this research presents a computational reasoning tool to help designers and engineers predict change …

Design Of Meta-Materials Outside The Homogenization Limit Using Multiscale Analysis And Topology Optimization, Christopher Czech

All Dissertations

The field of meta-materials engineering has largely expanded mechanical design possibilities over the last two decades; some notable design advances include the systematic engineering of negative Poisson's ratio materials and functionally graded materials, materials designed for optimal electronic and thermo-mechanical performances, and the design of materials under uncertainty. With these innovations, the systematic engineering of materials for design-specific uses is becoming more common in industrial and military uses. The motivation for this body of research is the design of the shear beam for a non-pneumatic wheel. Previously, a design optimization of a finite element model of the non-pneumatic wheel was …

Compressive Strength Of Continuous Fiber Unidirectional Composites, Ronald Thompson

All Dissertations

Dow and Rosen's work in 1965 formed an intellectual framework for compressive strength of unidirectional composites. Compressive strength was explained in terms of micro-buckling, in which filaments are beams on an elastic foundation. They made simplifying assumptions, with a two dimensional idealization and linearized material properties. This study builds on their model, recognizing that the shear mode of instability drives unidirectional compressive strength. As a necessary corollary, the predictive methods developed in this study emphasize correct representation of composite shear stiffness. Non-linear effects related to matrix material properties, fiber misalignment, three dimensional representation, and thermal prestrains are taken into account. …

Bubble Coalescence And Breakup Modeling For Computing Mass Transfer Coefficient, Ryan A. Mawson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Modeling fluid behavior with computer numerical models can be very difficult due to the physical phenomenon which can be present in complex fluid systems. One difficult situation to model is when there is more than one type of fluid in a system. Some of these systems include fluids which do not mix, such as is the case when a liquid and a gas are present. In this situation, the gas phase will form bubbles which are dispersed throughout the liquid phase. Modeling the breakup and coalescence of these bubbles is critical to correctly model this type of situation.

There exist …

The Use Of A Pylon Mounted Transducer For Investigating The Gait Of Transtibial Amputees, Justin Robert Brink

UNLV Theses, Dissertations, Professional Papers, and Capstones

Two areas of research interest in the design and use of lower limb prosthetic devices are how foot performance varies with design and how prosthesis alignment affects gait. The current study addressed both of these areas through the use of the JR3 triaxial transducer mounted at the base of the socket. The transducer is an innovative form of instrumentation that measures forces and moments at the end of the socket. Traditional measurement of gait uses a force plate buried in the floor of a gait laboratory. The study established that the transducer offers a viable means of instrumentation for amputee …

Upgrading Unlv's Astm E477 Test Facility To Meet The Current Standards Of Astm E477, Ronn Fojas

UNLV Theses, Dissertations, Professional Papers, and Capstones

A by-product of Heating, Ventilation, and Air-conditioning (HVAC) systems is noise that is produced by fans, compressors, and other related equipments and the noises from the turbulence that is created by moving air. Sometimes, it is impractical to modify the sources of the noise, which requires designers to modify the path of the noise, the duct system. These modifications might include installing an in-duct silencer or acoustical lining on the inside walls of the ducts. The testing and the precise quantification of the performance of these silencers and duct linings are necessary for any designer to be able to make …

Buffering Pv Output During Cloud Transients With Energy Storage, Yacouba Moumouni

UNLV Theses, Dissertations, Professional Papers, and Capstones

Consideration of the use of the major types of energy storage is attempted in this thesis in order to mitigate the effects of power output transients associated with grid-tied CPV systems due to fast-moving cloud coverage. The approach presented here is to buffer intermittency of CPV output power with an energy storage device (used batteries) purchased cheaply from EV owners or battery leasers. When the CPV is connected to the grid with the proper energy storage, the main goal is to smooth out the intermittent solar power and fluctuant load of the grid with a convenient control strategy. This thesis …

A Refreshable And Portable E-Braille System For The Blind And Visually Impaired, Mohammad Yousef Saadeh

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of this research is to design an affordable Braille tactile display that is wearable, refreshable, and portable. The device is intended to be used as an output device that can playback stored media. It can be also incorporated with current Braille reading technologies. The device will control both the electrical and mechanical stimulations to optimize the sensation and ensure extended use of the device. This work is concerned mainly with the mechanical aspects of the design.

This research proposed the development of a finger-wearable, scanning-style electric stimulation based (electrotactile) Braille display with sensing and adaptive rendering/actuation functions for …

Improving Efficiency And Capacity Of Hydro-Turbines In The Western United States, Hoover Dam, Jonathan Sanchez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal for this thesis is to minimize clearances and tolerances, in order to prevent water leakage. A proper seal on the seal rings does not let excess water flow through the turbine runner, thus conserving more water and wasting less energy. Moreover, water leakage past worn wear plates allows for an extra load for the turbine when operating in condense mode. When the wicket gates are closed, water leakage past worn plates wastes mechanical energy in the water; thus, decreasing the efficiency of the Francis turbine, especially when operating at partial loads. Furthermore, the wicket gates also known as …

A Conductivity Testing System Coupled With A Tensile Testing Machine To Measure The Surface Properties Of Polymer Specimens, Nguyen T. Nguyen

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

Polymers play an essential role in our everyday life due to their employment in a widespread range of applications. Polymers are used in industries such as space, biomedical, electronics, etc. in which their electrical and mechanical properties are major aspects which need to be investigated prior to implementation. When subjected to mechanical stimulations, polymers may exhibit changes in electrical conductivity which can vary locally within the specimens, especially in those of conducting polymers. In mechanical investigations a tensile testing machine is used to understand polymers’ strength, elasticity or other mechanical properties. In electrical analysis, using a four-point probe to examine …

Effective Thermal Conductivity Of Tri-Isotropic (Triso) Fuel Compacts, Charles P. Folsom

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Next Generation Nuclear Plant (NGNP) program objective is to develop a new type of nuclear reactor that produces process heat instead of electricity. The process heat can be used in the production of hydrogen and many other industrial processes. As part of the NGNP program a new type of nuclear fuel is being developed. The fuel is a composite construction of specially coated fuel particles and graphite pressed together in a cylindrical compact.

Thermal conductivity is an important thermophysical property of the fuel that needs to be measured. Knowledge of the thermal conductivity of the fuel will provide accurate …

Evaluation Of Turbulence Variable Distributions For Incompressible Fully Rough Pipe Flows, Emilie B. Fowler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The specific turbulent kinetic energy, root-mean-square fluctuating vorticity, and mean-vortexwavelength distributions are presented for fully rough pipe flow. The distributions of these turbulence variables are obtained from a proposed turbulence model. Many of the turbulence models commonly used for computational fluid dynamics are based on an analogy between molecular and turbulent transport. However, traditional k-ε and k-ω models fail to exhibit proper dependence on the molecular viscosity. Based on a rigorous application of the Boussinesq’s hypothesis, Phillips proposed a vorticity-based transport equation for the turbulent kinetic energy. The foundation for this vorticity-based transport equation is presented. In future development of …

Autocorrelation-Based Estimate Of Particle Image Density In Particle Image Velocimetry, Scott O. Warner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In Particle Image Velocimetry (PIV), the number of particle images per interrogation region, or particle image density, impacts the strength of the correlation and, as a result, the number of valid vectors and the measurement uncertainty. Therefore, any a-priori estimate of the accuracy and uncertainty of PIV requires knowledge of the particle image density. An autocorrelation-based method for estimating the local, instantaneous, particle image density is presented. Synthetic images were used to develop an empirical relationship based on how the autocorrelation peak magnitude varies with particle image density, particle image diameter, illumination intensity, interrogation region size, and background noise.

This …