Mechanical Engineering Commons^™

Ultrasonic Angioplasty: Assessing The Risk Of Arterial Perforation, Mark Wylie, Garrett Mcguinness, Graham Gavin

Conference Papers

Atherosclerosis is a cardiovascular disease that effects large and medium muscular arteries (such as coronary and iliac) and also large elastic arteries (such as aorta) [1]. It causes thickening of the arterial wall and over time can result in a completely blocked artery or chronic total occlusion (CTO). While the majority of atherosclerotic lesions can be attempted by typical Percutaneous Transluminal Coronary Angioplasty (PTCA) such as balloon and stent implantation, calcified CTOs are often problematic as they do not lend themselves to be accessed by the guidewire which is required to implant the balloon and stent. Excessive guidewire pushing force …

The Effect Of Air Preheating In A Biomass Cfb Gasifier Using Aspen Plus Simulation, Wayne Doherty, Anthony Reynolds, David Kennedy

Articles

In the context of climate change, increasing efficiency and energy security, biomass gasification is likely to play an important role in energy production. Atmospheric circulating fluidised bed (CFB) technology was selected for the current study. The primary objective of this research is to develop a computer simulation model of a CFB biomass gasifier that can accurately predict gasifier performance under various operating conditions. An original model was developed using ASPEN Plus (Advanced System for Process ENgineering Plus). The model is based on Gibbs free energy minimisation. The restricted equilibrium method was used to calibrate the model against experimental data. This …

Renewable Energy Resources And Technologies Applicable To Ireland, Fergal O'Rourke, Fergal Boyle, Anthony Reynolds

Articles

The energy consumed in Ireland is primarily achieved by the combustion of fossil fuels. Ireland’s only indigenous fossil fuel is peat; all other fossil fuels are imported. As well as fossil fuels continually becoming more expensive, their use as an energy source also has a negative impact on the environment. Ireland’s energy consumption can be separated into 3 divisions; transportation, electricity generation and heat energy. Ireland however has a vast range of high quality renewable energy resources. Ireland has set a target of 33% of its electricity will be generated from renewable sources by 2020[1]. The use of biomass, wind …

Simulation Of A Tubular Solid Oxide Fuel Cell Stack Operating On Biomass Syn-Gas Using Aspen Plus, Wayne Doherty, Anthony Reynolds, David Kennedy

Articles

A tubular solid oxide fuel cell (SOFC) stack is modelled and its operation on biomass syn-gas is investigated. The objective of this work is to develop a computer simulation model of a biomass gasification-SOFC (BG-SOFC) system capable of predicting performance under various operating conditions and using diverse fuels. The stack is modelled using Aspen Plus and considers ohmic, activation and concentration losses. It is validated against published data for operation on natural gas. Operating parameters such as fuel and air utilisation factor (U_f and U_a), current density (j) and steam to carbon ratio ( …

Modeling And Simulation Of Electrochemical Magneto Hydro Dynamics, Debamoy Sen

Masters Theses

"This thesis focuses on how the electrochemical magneto hydro dynamic problem is solved through numerical simulation for a two dimensional millielectrode electrochemical cell and a three dimensional microelectrode array cell. Electrochemical processes are enhanced by magnetic fields through the introduction of body forces such as Lorentz force. Through modeling and numerical simulations, experimental results can be integrated with theory. Such simulations will aid in the prediction of mass transfer limited currents and visualization of flow profiles in an electrochemical cell. The numerical solution of the equation system is made possible by the finite volume method used in the FLUENT Computational …

An Investigation On The Dynamic Behavior Of An Overhead Valve Actuating Mechanism, Michael Noonan

Theses

This project involves the measurement and simulation of the dynamic performance of a pushrod valvetrain, in particular that of the outer valve spring. The engine was donated by S&S Cycle Wisconsin. A motoring test rig was constructed to obtain high speed camera footage of the spring coils motion. Individual static spring coil displacement measurements were taken, and their stiffness studied. Spring and pushrod natural resonant frequencies were measured. All data acquisition and analysis was carried out with Labview programs written during the project. Programs were written to model individual static coil stiffness using the close coil, open coil, and theories …

Modelling And Simulation Of A Biomass Gasification-Solid Oxide Fuel Cell Combined Heat And Power Plant Using Aspen Plus, Wayne Doherty, Anthony Reynolds, David Kennedy

Conference Papers

In this paper the operation and performance of a high temperature solid oxide fuel cell (SOFC) stack on biomass syn-gas from a demonstration biomass gasification combined heat and power (CHP) plant is investigated. The objective of this work is to develop a computer simulation model of a biomass-SOFC CHP system, flexible enough for use in industry, capable of predicting system performance under various operating conditions and using diverse fuels. The biomass gasifier is of the dual fluidised bed (DFB) type with steam as the gasifying agent and is operated at atmospheric pressure. The tubular SOFC configuration, developed by Siemens Power …

Alternative Sources Of Energy, David Kennedy

Conference Papers

Ireland relies on imports of fossil fuels for up to 83% of its energy needs and this statistic is relatively common in other European countries. Apart from the high import costs and pollutions associated with fossil fuels and the need to meet new targets in terms of CO2 emissions, energy security is essential. This paper provides an overview and outline of the different alternative energy sources available for use either at domestic or on large scale production, some of which are established and others less likely to succeed in our climate.
Some of the alternative energy sources such as wind …

Analysis Of Factors Causing Failure Mode For Automotive Hitch Control System Calibration In Agriculture Equipment, Setordji Yao Abotsi

Dissertations and Theses @ UNI

Traditionally, agricultural tractors have used hydro-mechanical draft control systems to mechanically sense implement draft. Technological development of low cost, reliable microprocessors has contributed to allowing greater flexibility in designing agricultural tractor control systems (Rutkowski & Welchens, 1986). To successfully control the depth of which an implement penetrates the ground, it has become imperative to incorporate a draft control system on agricultural tractors. The control system operates by responding to the draft load or force acting on the tractor. Increasing the draft load or force allows the implement to be raised and decreasing the draft load or force allows the implement …

Explicit Finite Element Modeling Of Knee Mechanics During Simulated Dynamic Activities, Mark A. Baldwin

Electronic Theses and Dissertations

The natural knee is one of the most commonly injured joints in the body due to relatively high loads and motions that can lead to debilitating degenerative diseases such as osteoarthritis. Total knee arthroplasty is a clinically successful method for eliminating pain in the osteoarthritic knee, but is subject to complications that can affect patient satisfaction and long-term implant performance. The work presented in this dissertation is a demonstration of how anatomic three-dimensional (3D) computational knee models can be an effective alternative for investigating knee mechanics when compared to the cost and time prohibitive nature of in-vivo and in-vitro methods. …

The Magnetoelectric Effects In Multiferroic Composite Nanofibers, C. L. Zhang, W. Q. Chen, S. H. Xie, J. S. Yang, Jiangyu Li

Department of Engineering Mechanics: Faculty Publications

In this letter, we analyze the quasistatic and dynamic magnetoelectric responses of multiferroic composite nanofibers consisting of both ferroelectric and ferromagnetic phases and demonstrate that the nanofibers exhibit magnetoelectric responses orders of magnitude higher than multiferroic composite thin films of similar compositions. The analysis suggests that the multiferroic nanofibers are promising for magnetoelectric applications.

Harvesting Magnetic Energy Using Extensional Vibration Of Laminated Magnetoelectric Plates, C. L. Zhang, J. S Yang, W. Q. Chen

Department of Engineering Mechanics: Faculty Publications

Magnetically forced extensional vibrations of laminated plates with piezoelectric and piezomagnetic layers are analyzed theoretically. It is shown that such a structure can be used to harvest magnetic energy and convert it to electric energy. The output power and the energy conversion efficiency are calculated. The load dependence of the magnetoelectric coupling coefficient is also obtained.

Real-Time Depth Sectioning: Isolating The Effect Of Stress On Structure Development In Pressure-Driven Flow, Lucia Fernandez-Ballester, Derek W. Thurman, Julia A Kornfield

Department of Engineering Mechanics: Faculty Publications

Transient structure development at a specific distance from the channel wall in a pressure-driven flow is obtained from a set of real-time measurements that integrate contributions throughout the thickness of a rectangular channel. This “depth sectioning method” retains the advantages of pressure-driven flow while revealing flow-induced structures as a function of stress. The method is illustrated by applying it to isothermal shear-induced crystallization of an isotactic polypropylene using both synchrotron x-ray scattering and optical retardance. Real-time, depth-resolved information about the development of oriented precursors reveals features that cannot be extracted from ex-situ observation of the final morphology and that are …

Evaporation Induced Two-Dimensional Buckling Within Liquid Droplet, Ziguang Chen, Maozi Liu, Gang-Yu Liu, Li Tan

Department of Engineering Mechanics: Faculty Publications

Evaporation of a liquid droplet containing a thin layer of surfactants atop could generate two-dimensional buckling on surfaces. Herringbone features were produced via embedded nanoparticle beds. We assign transient surface tension as the driving force for such a phenomenon. Considering the surfactant layer as a thin elastic film, a continuum model is employed to calculate the mechanical properties of the layer. Particularly, we estimated an elastic modulus of 4 GPa for the surfactant layer, indicating rather strong mechanical properties of these small molecules when they are close packed to form supramolecules via noncovalent binding.

Two-Tank Indirect Thermal Storage Designs For Solar Parabolic Trough Power Plants, Joseph E. Kopp

UNLV Theses, Dissertations, Professional Papers, and Capstones

The performance of a solar thermal parabolic trough plant with thermal storage is dependent upon the arrangement of the heat exchangers that ultimately transfer energy from the sun into steam. The steam is utilized in a traditional Rankine cycle power plant. The most commercially accepted thermal storage design is an indirect two-tank molten salt storage system where molten salt interacts with the solar field heat transfer fluid (HTF) through a heat exchanger. The molten salt remains in a closed loop with the HTF and the HTF is the heat source for steam generation. An alternate indirect two tank molten salt …

Optimization Of Channel Geometry In A Proton Exchange Membrane (Pem) Fuel Cell, Jephanya Kasukurthi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Bipolar plates are the important components of the PEM fuel cell. The flow distribution inside the bipolar plate should be uniform. Non-uniform flow distribution inside the bipolar leads to poor performance of the fuel cell and wastage of expensive catalyst. A single channel PEM fuel cell is taken and electrochemical analysis is carried out on it. The results are compared with the available published experimental data obtained by other research group, and they are found to be in good agreement. A baseline design of the bipolar plate is taken and numerical analysis is carried out. The results show that the …

Criticality Studies Of Actinides Within Fissures, Trevor Wilcox

UNLV Theses, Dissertations, Professional Papers, and Capstones

The storage of nuclear waste in underground storage facilities presents numerous engineering challenges and risks. Experimental verification of engineered underground storage is impractical or prohibitively expensive, leaving scientists with few options. A 1995 report by Bowman and Venneri of the Los Alamos National Laboratory generated considerable controversy by hypothesizing that wastes composed of fissionable plutonium leached from underground storage containers could pose a nuclear criticality hazard. They proposed cases where plutonium collected in underground fractures could lead to sustained nuclear fission. In overmoderated cases, they argued that the resulting release of energy from fission could result in steam explosions, or …

Oxidation Modeling By Means Of Molecular Dynamics, Chaiyod Soontrapa

UNLV Theses, Dissertations, Professional Papers, and Capstones

Oxidation modeling is normally engineered to study systems at macroscopic scales, mostly in analytical forms based on diffusion theories. The associated time scale is usually in months, days, or minutes, and the length scale is in the order of microns. In this dissertation, oxidation modeling is performed at atomistic scale with the time and length scales in picoseconds and angstroms, respectively, using molecular dynamics. Molecular dynamics simulations generate trajectories of each atom or particle in a system according to the laws of physics. Studying oxidations under the atomistic point of view can offer new insights on atomic behaviors and influencing …

Fracture Toughness, Crack-Growth-Rate And Creep Studies Of Alloy 276, Joydepp Pal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Austenitic nickel-base Alloy 276 had been proposed to be a candidate structural material within the purview of the nuclear hydrogen initiative program. A mechanistic understanding of high temperature tensile deformation of this alloy has already been presented in an earlier investigation. The current investigation has been focused on the evaluation of crack-growth behavior, fracture toughness, stress-corrosion-cracking and creep deformation of this alloy as functions of different metallurgical and mechanical variables. The results of crack-growth study under cyclic loading indicate that this alloy exhibited greater cracking tendency with increasing temperature at a constant load ratio (R). However, the effect of temperature …

Experimental And Numerical Study Of A Proton Exchange Membrane Electrolyzer For Hydrogen Production, Sachin S. Deshmukh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen as a fuel source has received attention from researchers globally due to its potential to replace fossil based fuels for energy production. Research is being performed on hydrogen production, storage and utilization methods to make its use economically feasible relative to current energy sources. The PEM electrolyzer is used to produce hydrogen and oxygen using water and electricity. Focus of our study is to provide a benchmark experiment and numerical model of a single cell electrolyzer that can assist in improving the current state of understanding of this system. Parametric analysis of an experimental cell was performed to understand …

Effects Of Mechanical And Metallurgical Variables On Creep, Fracture Toughness And Crack Growth Behavior Of Alloy 617, Muhammad Hasibul Hasan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nickel base Alloy 617 has been identified to be a suitable structural material for heat exchanger applications in both hydrogen and electricity generation using nuclear heat. A maximum operating temperature of 950°C has been specified by department of energy (DOE) for both applications to achieve a maximum possible efficiency. Therefore, an extensive investigation has been pursued to evaluate time-dependent-deformation (Creep) of this alloy as functions of temperature and applied load. The results indicate that this alloy exhibited severe creep deformation, characterized by development of an instantaneous tertiary creep region at 850 and 950°C under applied stresses corresponding to its 35% …

Mitigation Of Impact Vibrations Using Impedance Mismatch In Cylindrical Structures, Sachiko Sueki

UNLV Theses, Dissertations, Professional Papers, and Capstones

The focus of this work is to study the phenomenon of material impedance mismatch to determine its effect on the mitigation of high frequency accelerations in projectile and long bar structures within linear ranges of materials. In this study, the acceleration responses of structures with various materials and material combinations were studied experimentally, numerically and by the Finite Element Analysis (FEA). Air-gun tests conducted by the US Army Research Laboratory were modeled using FEA to simulate the acceleration pulse and shock waves experienced by artillery components during a launch. After the prototype of projectile was selected, further studies were conducted …

Design And Characterization Of A Shock And Vibration Mitigation Seat System, George Samaan Ladkany

UNLV Theses, Dissertations, Professional Papers, and Capstones

Extensive research has been conducted into the development of pneumatic seatbladder systems for shock and vibration mitigation for use in current U.S military vehicle envelopes. This research expands on the previous work through an elaborate experimental characterization of four prototype air bladder seat cushion systems. The experimental characterization conducted included shock testing, continuous vibration, and internal dynamic pressure measured during the shock event.

The shock testing was conducted both at the Army Research Lab as well at UNLV. The shock testing conducted at UNLV was performed on a drop tower designed and constructed during the time of this research. The …

Empirically Derived Formulas To Predict Indoor Maximum, Average, And Minimum Temperatures In Roofpond Buildings Using Minimum Climatic Information, Ibrahim Kivarkis Kako

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis introduces an empirically developed formula to predict the comfort conditions and thermal performance of a Skytherm(TM) Southwest Roofpond placed over a light-weight un-insulated structure built at the School of Architecture at the University of Nevada, Las Vegas.

The predictive formula introduced in this study may be used in different parts of the world (particularly developing nations where insulation and air-conditioning are rarely used) to predict the performance of a Skytherm(TM) Southwest Roofpond using minimal climate data.

The data collected in the experimental setup at the Natural Energies Advanced Technologies Laboratory included outside and inside temperatures of various surfaces …

Thermal Converter Devices, Systems And Control Methods, Richard A. Flanagan, Rod E. Hosilyk, Rob Arlt, Kakkattukuzhy M. Isaac, Ronald E. Loving, David Alan Gordon

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A system is provided for reducing exhaust emissions. The system can comprise a series of chambers, an injector head, and a controller. The controller can maintain desired temperature zones and chemical environments inside the series of chambers, and the chambers and structures inside the system 10 can provide a desired travel path for the air, fuel, and untreated exhaust mixture inside.

An Evaluation Of The Traveling Wave Ultrasonic Motor For Force Feedback Applications, Nishant Venkatesan

University of Kentucky Master's Theses

The traveling wave ultrasonic motor is considered for use in haptic devices where a certain input-output relation is desired between the applied force and the resulting motion. Historically, DC motors have been the standard choice for this purpose. Owing to its unique characteristics, the ultrasonic motors have been considered an attractive alternative. However, there are some limitations when using the ultrasonic motor for force-feedback applications. In particular, direct torque control is difficult, and the motor can only supply torque in the direction of motion. To accommodate these limitations we developed an indirect control approach. The experimental results demonstrate that the …

Applications Of Computational Fluid Dynamics To Planetary Atmospheres, Xiaolong Deng

University of Kentucky Doctoral Dissertations

Computational Fluid Dynamics (CFD) has been applied to many areas. As one of the most important fluids, the atmosphere is closely related to people’s life. Studying the atmospheres on other planets can help people understand the Earth’s atmosphere and the climate and weather phenomena in it. Because of the complexity of a planetary atmosphere and the limitation of observations, applying CFD to the study of planetary atmospheres is becoming more and more popular. This kind of CFD simulations will also help people design the mission to the extra planets.

In this dissertation, through CFD simulations, we studied the three important …

An Algorithm To Solve The Associative Parallel Machine Scheduling Problem, Mohannad Abdelrahman Shuaib

University of Kentucky Master's Theses

Effective production scheduling is essential for improved performance. Scheduling strategies for various shop configurations and performance criteria have been widely studied. Scheduling in parallel machines (PM) is one among the many scheduling problems that has received considerable attention in the literature. An even more complex scheduling problem arises when there are several PM families and jobs are capable of being processed in more than one such family. This research addresses such a situation, which is defined as an Associative Parallel Machine scheduling (APMS) problem. This research presents the SAPT-II algorithm that solves a highly constrained APMS problem with the objective …

Nanomechanical Characterizations Of High Temperature Polymer Matrix Composite Resin: Pmr-15 Polyimide, David C. Jones

University of Kentucky Master's Theses

High Temperature Polymer Matrix Composites (HTPMCs) are widely used by the aerospace industry today because of their high specific strengths, light weight, and the ability to custom tailor their mechanical properties to individual applications. Because of the harsh environmental conditions these materials experience during service use, these composite structures are susceptible to a high rate of thermo-oxidative degradation that ultimately causes premature failure in service. The current knowledge base is lacking in the fundamental spatial variability of the constituent materials upon aging, which precludes composite developers from predicting lifetime mechanical properties of the composites in use. The current study summarizes …

Information Archival And Reuse: Drawing Conclusions From The Past, Matt R. Bohm

Doctoral Dissertations

"Over the last few decades design researchers have put forward theories and proposed methodologies that increase the chance that a design team will reliably arrive at the optimal solution to a given design problem. Studies, however, bear out that theories and methodologies alone will not guarantee an optimal or even good design solution. Instead, a breadth of knowledge across multiple engineering domains and the time and tools to thoroughly evaluate the design space are as important as any prescriptive design method. This work presents a set of underlying engineering technologies to define, archive and reuse product design knowledge to provide …