Engineering Commons^™

Design And Evaluation Of A High Temperature/Pressure Supercritical Carbon Dioxide Direct Tubular Receiver For Concentrating Solar Power Applications, Jesus Daniel Ortega

Open Access Theses & Dissertations

This work focuses on the development of a solar power thermal receiver for a supercritical-carbon dioxide (sCO2), Brayton power-cycle to produce ~1 MWe. Closed-loop sCO2 Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. High temperatures (923 - 973 K) and pressures (20 - 25 MPa) are required in the solar receiver to achieve thermal efficiencies of ~50%, making concentrating solar power (CSP) technologies a competitive alternative to current power generation methods. In this study, the CSP receiver is required to achieve an outlet temperature of …

Digitally Manufactured Spatially Variant Photonic Crystals, Javier Jair Pazos

Open Access Theses & Dissertations

Metamaterials and photonic crystals are engineered composites that exhibit electromagnetic properties superior to those found in nature. They have been shown to produce novel and useful phenomena that allow extraordinary control over the electromagnetic field. One of these phenomena is self-collimation, an effect observed in photonic crystals in which a beam of light propagates without diffraction and is forced to flow in the direction of the crystal. Self-collimation however, like many of the mechanisms enabled through dispersion engineering, is effective in directions only along the principal axes of the lattice. To this effect, a general purpose synThesis procedure was developed …

Synthesis, Microstructure And Performance Evaluation Of Gadolinium Incorporated Cobalt Ferrite Ceramics, Md Taibur Rahman

Open Access Theses & Dissertations

Spinel structured ferrites exhibit remarkable properties and phenomena, which are attractive for application in sensors and actuators, magneto-electronics, and electrochemical energy storage devices. Among spinel ferrites, cobalt ferrite CoFe₂O₄ (CFO) has attracted remarkable attention and widely studied because of their electro-magnetic properties, chemical stability and mechanical hardness. The properties and phenomena of CFO ceramics are dependent on microstructure and chemistry, which in turn depend on the synThesis processes and conditions employed for fabrication. Generally exact chemical composition, processing temperature, reactive or processing atmosphere (if any) and the ions that substitute Fe³⁺/Fe²⁺ ions dictate the …

Design And Development Of Implantable And Remote Controlled Distraction Osteogenesis Device For Limb Lengthening Practice In Children, Mario Eduardo Rodriguez De La O

Open Access Theses & Dissertations

Recent technology improvements have been positively affecting medical industry in recent years since procedures and equipment are more precise and reliable. Nevertheless, there are still surgical procedures and medical devices that not fully address specific needs according to medical experts. One of those necessities is focused on options available for children patients when subjected to a surgical procedure named distraction osteogenesis. In general, distraction osteogenesis is performed when skeletal deformities need to be corrected or when bone lengthening is required, typically a mechanism is utilized to elongate bone at a controlled rate. The existing osteodistraction methods for limb lengthening and …

Permit Tool: Development Of An Algorithm To Determine Performance Life Of Hma Mixes In Texas, Luis Alberto Torres Escobedo

Open Access Theses & Dissertations

A number of hot mix asphalt (HMA) types, such as permeable friction course (PFC), stone mastic asphalt (SMA), performance design mixes and conventional dense graded mixes are currently used to construct or overlay Texas roads. One of the important inputs into current pavement design programs used by the Texas Department of Transportation (TxDOT) is the performance lives of HMA mixes. To determine the best mix type for a particular job or to analyze the performance of a mix or a road, a new system can be developed to rationally quantify the HMA mix performance. This system must have access to …

An Experimental Investigation On Liquid Methane Convection And Boiling In Rocket Engine Cooling Channels, Abraham Trujillo

Open Access Theses & Dissertations

In the past decades, interest in developing hydrocarbon-fueled rocket engines for deep spaceflight missions has continued to grow. In particular, liquid methane (LCH4) has been of interest due to the weight efficiency, storage, and handling advantages it offers over several currently used propellants. Deep space exploration requires reusable, long life rocket engines. Due to the high temperatures reached during combustion, the life of an engine is significantly impacted by the cooling system's efficiency. Regenerative (regen) cooling is presented as a viable alternative to common cooling methods such as film and dump cooling since it provides improved engine efficiency. Due to …

Predicting Propylene Loss With Inferential Model Development Using Design Of Experiments (Doe) And Historical Data, Jeffrey Allen Wheeler

Open Access Theses & Dissertations

Inferential models are a highly researched topic as the science of digital automation becomes more prevalent as information is in abundance. Welldeveloped inferred models can augment the use of analyzers in steady state processing and highly correlated ones can even replace online analytics. The use of design of experiments (DOE) inferred models with historical process data and a rigorous plant simulator can reduce the case study duration while achieving a high degree of accuracy. This paper uses surface response and full factorial models as the first step in model development, and then uses actual historical plant data to create a …

The Interfacial Fracture Of Bonded Materials And Composites, Kai Zhao

Open Access Theses & Dissertations

Adhesive bonding and composite materials have been widely used in manufacturing industry. Failure results from the weakest link in a structure and this is often the interface between two materials. In case of composites, it becomes the fiber and matrix interface. In case of bonded polymers, the bonding line is the interface. This Dissertation is focused on the interfacial fracture of bonded materials and composites. First, a systematic experimental investigation on adhesive bonding strengths of polymer/polymer and polymer/metal joints was conducted and the experimental results were compared with other researchers' work. Then, a modified short-beam shear approach is developed to …

Enhanced Finite Element Modeling Of The Thermo-Mechanical Responses Of Jointed Pcc Pavements Under Environmental And Traffic Loads, Mohammad Ali Zokaei Ashtiani

Open Access Theses & Dissertations

Jointed plain concrete pavements (JPCP) are the most commonly used type of rigid pavement systems and the accurate modeling of their thermo-mechanical responses is of primary importance in a mechanistic-empirical pavement design procedure. In JPCP, the temperature gradient and resulting slab shape play a crucial role in the magnitude of stresses and deflections caused by the superimposed traffic loads. Temperature gradients through the slab depth can produce thermal curling in slabs and can also produce slab expansion and contraction, which leads to the generation of frictional tractions between slabs and foundation. The prediction of these frictional tractions is complicated by …

Frequency Selective Surfaces For Extreme Applications, Jay Houston Barton

Open Access Theses & Dissertations

It is known that for high-power microwaves and other extreme environments, the use of resonant metallic elements in frequency selective surfaces can be problematic. The solution developed within this Dissertation to solve these problems was to use guided-mode resonance phenomenon to create all-dielectric frequency selective surfaces that could survive these extreme environments.

To fully understand how these devices work, three different computational electromagnetic methods are formulated and implemented. The formulation of these methods start with the differential form of Maxwellâ??s equation and are derived all the way down to the final simulation state. This is done sequentially and all the …

Development Of A Variable Stiffness Locally Adjustable And Repairable Low-Cost Energy Storage And Return Carbon Fiber Prosthetic Foot: A Feasibility Study, Joshua Scott Bowen

Open Access Theses & Dissertations

Background: Energy storage and return (ESAR) prosthetic feet were developed to improve the mobility and function of lower-limb amputees. Amputees in the Developing World amputees lack this technology. Most current Developing World prosthetic solutions do not adequately address the needs of active amputees and were not designed to pass international standard tests. Developing a low-cost, repairable, adjustable, energy storage and return prosthetic foot would close this technological gap and improve the mobility and function of active amputees. The goal of this research is to determine the feasibility of fabricating a low-cost, adjustable, ESAR, repairable prosthetic foot manufactured from carbon fiber …

3d Printed Spatially Variant Anisotropic Metamaterials, Cesar Roman Garcia

Open Access Theses & Dissertations

The recent advancement in 3D printing has created a new way to design electronics and electromagnetic devices. This allows for a new breed of non-planar designs to be used, fully exploiting all three dimensions like never before. More functions can be fit into the same amount of space, products with novel form factors can be more easily manufactured, interconnects can be routed more smoothly, interfaces can be better implemented, electrical and mechanical functions can be comingled, and entirely new device paradigms will be invented. When departing from traditional planar topologies many new problems arise like signal integrity, crosstalk, noise, and …

A Study Of Ti-Doped Wo3 Thin Films Using Comparative Theoretical And Experimental Approach, Aurelio Paez

Open Access Theses & Dissertations

Metal oxides like Tungsten Oxide (WO3) are well documented and characterized in the literature, with uses in darkening windows and mirrors, flat computer displays, solar panel cooling, and sensors (of interest in this study). Ti doping of WO3 is less documented and the focus of this study. Sample thin films of pure WO3 and varyingly Ti doped WO3 were prepared using Radio Frequency magnetron sputtering (RF) (13.56 MHz) to grow thin films on a silicon substrate. This study aims to compare multiple Ti doping percentages in WO3 theoretically and then compare with experimental data taken from thin films of various …

Use Of Cosine Modulated Filter Bank To Quantify Human Muscle Fatigue Using Electromyography Signals Obtained During Isometric Voluntary Contractions, Liza Stephanie Rodriguez

Open Access Theses & Dissertations

As technology continues to advance, there continues to be an interest in applying engineering theories to solve medical problems. Technology has allowed researchers to investigate the properties and characteristics of the human body in hopes of emulating their complexities. The rising interest in the study of biopotentials for use in prosthetic limbs, exoskeletons and machine interfacing has led to a necessity to validate that the understanding of these signals is accurate. The study of biopotentials generated by muscles via a method known as electromyography (EMG) has improved the understanding of effects of rehabilitative treatments, assisted in diagnosing diseases, control of …

Effect Of Multi-Tube Injector Geometry On Flame Stability And Nox Emission In A High Pressure Gas Turbine Combustor, Sudipa Sarker

Open Access Theses & Dissertations

Future generation gas turbine combustors for power production are expected to have the capability of operating on high hydrogen content fuels. To ensure the implementation of high hydrogen content (HHC) fuel in a power generation unit without negotiating with operational or emission advantages, the study of the flame stability regime and behavior of (HHC) fuel under gas turbine condition leads to the necessity of the development of an optically accessible high-pressure combustor. This Dissertation first presents the design of an optically high-pressure combustor facility based on 500 kW power and 1.5 MPa pressure which is the representative pressure of a …

Evaluation Of Ozone Trends In Southern Doña Ana County, New Mexico Thru Wind Rose Analysis And Use Of Noaa Hysplit Model, Maria Aurelia Sisneros

Open Access Theses & Dissertations

The objective of this study was to determine whether increasing ozone concentrations in 2012 and 2013 at the Santa Teresa air quality monitor in Doña Ana County, New Mexico were due to a local point source impacting this monitor only or part of a regional phenomenon that affects all the monitors within the Paso del Norte Region. In addition, the study focused on identifying local and regional/long-range source areas contributing transport ozone to the study area (southern Doña Ana County).

The study showed that increasing ozone levels were not unique to the Santa Teresa monitor due to the fact that …

Transatlantic Maritime Transportation Between The Czech Republic And The United States, Petr Toman

Open Access Theses & Dissertations

Maritime transportation is the backbone of today´s world trade and therefore there special attention should be paid to all subjects concerning this mode of transportation. It is also necessary to complement maritime transportation by other modes, such as rail and/or truck (road). This thesis deals with the problems of maritime transportation and provides the summary of recent developments, trends and statistics mainly on Transatlantic maritime routes (Europe to U.S.). Besides maritime transportation, this thesis also reviews the trends and statistics of rail and truck (road) transportation in U.S. and Europe.

The second part of thesis seeks to create a mathematical …

An Experimental Investigation Of The Cooling Channel Geometry Effects On The Internal Forced Convection Of Liquid Methane, Adrian Trejo

Open Access Theses & Dissertations

Rocket engine fuel alternatives have been an area of discussion for use in high performance engines and deep spaceflight missions. In particular, LCH4 has showed promise as an alternative option in regeneratively cooled rocket engines due to its non-toxic nature, similar storage temperatures to liquid oxygen, and its potential as an in situ resource. However, data pertaining to the heat transfer characteristics of LCH4 is limited. For this reason, a High Heat Transfer Test Facility (HHTTF) at the University of Texas at El Paso's (UTEP) Center for Space Exploration Technology and Research has been developed for the purpose of flowing …

Sustainable Public Transportation In Large Cities: Demand Estimation, Tadeas Umlauf

Open Access Theses & Dissertations

Public transportation helps to decrease the negative externalities caused by people's mobility. In many countries, the total number of vehicles and traffic has risen many times in the last decades but there is limited space to improve infrastructure in the cities. Large cities all over the world have a lot of issues with congestion, traffic noise, emission of greenhouse gases, and accidents. According to many international examples, sustainable public transportation in combination with synergistic projects (park & ride, kiss & ride, bike & ride) can help to overcome these issues. Therefore new transit modes and routes have been implemented in …

A Robust Algorithm For Estimating The Balance Of Autonomic Nervous System With Application To Mental Fatigue Detection Using Photoplethysmographic (Ppg) Signals, Ajay Kumar Verma

Open Access Theses & Dissertations

Spectral- and time-domain analysis of Heart Rate Variability (HRV) signal is widely used as a quantitative marker of the Autonomic Nervous System (ANS) activity. A robust algorithm was developed to derive HRV from photoplethysmographic (PPG) signals, to compute FFT- and AR-based spectra of these HRV signals, and to determine time- and frequency-domain features. This algorithm has detrending, sample-rate reductions, false-peak removal, automatic peak detection, peak-to-peak (P-P) interval detection and correction, time-domain feature extraction, HRV signal generation, and spectral-domain feature extraction from the HRV signal. Adapting to the very low spectral contents of the input PPG signal is very helpful in …

Direct Classification Of All American English Phonemes Using Signals From Functional Speech Motor Cortex, Emily M. Mugler, James L. Patton, Robert D. Flint, Zachary A. Wright, Stephan U. Schuele, Joshua Rosenow, Jerry J. Shih, Dean J. Krusienski, Marc W. Slutzky

Electrical & Computer Engineering Faculty Publications

Although brain-computer interfaces (BCIs) can be used in several different ways to restore communication, communicative BCI has not approached the rate or efficiency of natural human speech. Electrocorticography (ECoG) has precise spatiotemporal resolution that enables recording of brain activity distributed over a wide area of cortex, such as during speech production. In this study, we investigated words that span the entire set of phonemes in the General American accent using ECoG with 4 subjects. We classified phonemes with up to 36% accuracy when classifying all phonemes and up to 63% accuracy for a single phoneme. Further, misclassified phonemes follow articulation …

A Comparative Analysis Of Spatial Visualization Ability And Drafting Models For Industrial And Technology Education Students, Petros Katsioloudis, Vukica Jovanović, Mildred Jones

Engineering Technology Faculty Publications

The article presents the comparative study on the drafting models and spatial visualization ability of industrial and technology education students in the U.S. It discusses how the study was conducted which examined the issue based on technical drawings and with regards to the impacts of model types. The results reportedly revealed three-dimensional models are effective for promoting learning, however more studies have to be conducted.

Implementing Mechatronics Design Methodology In Mechanical Engineering Technology Senior Design Projects At The Old Dominion University, Vukica M. Jovanovic, Jennifer G. Michaeli, Otilia Popescu, Moustafa R. Moustafa, Mileta Tomovic, Alok K. Verma, Cheng Y. Lin

Engineering Technology Faculty Publications

In recent years, the nature of engineering design has changed due to advances in embedded system design and computer technologies. It is rare to engineer a purely mechanical design that does not incorporate electrical and electronic components. Mechanical engineers and mechanical engineering technologists must possess a multi-disciplinary knowledge with the understanding of both mechanical and electrical systems. For this purpose, undergraduate programs in engineering technology have added mechatronics courses to their curriculum. Mechatronics is a design process that is multi-disciplinary in nature and integrates principles of many engineering disciplines including, but not limited to, mechanical engineering, electrical engineering, and controls …

Hands-On Homework Or Laboratory Development For Distance Learning Students In Programmable Logical Controller (Plc), Cheng Y. Lin, Yuzhong Shen, Mileta Tomovic

Engineering Technology Faculty Publications

When teaching PLC classes in the distance-education (DE) program, one of the main problems is to provide hands-on experience to students. This is because students can only use design software to complete their homework and lab problems without being able to touch PLCs or wire ladder logic diagrams. In this paper, the authors develop a virtual laboratory to help DE students gain hands-on wiring experience in the automation control classes. The development significantly shortens the gap on the issue of hands-on experience between on-campus students and DE students. To increase the performance of safety and effectiveness, on-campus students can also …

Strategies For Effective Online Course Development, Carol L. Considine, Michael W. Seek, Jon Lester

Engineering Technology Faculty Publications

Old Dominion University's Civil Engineering Technology (CET) program has a successful history of distance education, with more than half of the student population comprised of distance learners. Distance learning delivery has traditionally been via satellite and videostreaming with students having the choice of asynchronous or synchronous options. The university is in the process of updating their distance learning technologies and has encouraged programs to migrate to an online modality of distance learning. Developing and delivering online courses requires different competencies and facilitation skills than video streamed synchronous delivery or face to face instruction. A course delivered online changes the teaching …

A Polymer Microdevice For Tensiometry Of Insoluble Components, Christopher L. Wirth

Faculty Scholarship

A semi-flexible SU-8 polymer microdevice was designed to deflect in response to a change in surface tension at an air-water interface. The suspended microtensiometer encloses a clean water-air interface, while externally the device is surrounded by an interface containing an insoluble component. The difference in surface tension between the inside and outside of the device, called the surface pressure, causes the device to deflect. Finite element simulations were performed to predict device behavior prior to fabrication. Finished devices were tested in a Langmuir trough during multiple compression and expansion cycles, using a platinum Wilhelmy plate for an independent surface pressure …

Hybrid Of Natural Element Method (Nem) With Genetic Algorithm (Ga) To Find Critical Slip Surface, Shahriar Shahrokhabadi, Vahid Khoshfahm, Hamed Nabizadeh Rafsanjani

Durham School of Architectural Engineering and Construction: Faculty Publications

One of the most important issues in geotechnical engineering is the slope stability analysis for determination of the factor of safety and the probable slip surface. Finite Element Method (FEM) is well suited for numerical study of advanced geotechnical problems. However, mesh requirements of FEM creates some difficulties for solution processing in certain problems. Recently, motivated by these limitations, several new Meshfree methods such as Natural Element Method (NEM) have been used to analyze engineering problems. This paper presents advantages of using NEM in 2D slope stability analysis and Genetic Algorithm (GA) optimization to determine the probable slip surface and …

Wetland Issues Affecting Waterfowl Conservation In North America, Heath M. Hagy, Scott C. Yaich, John W. Simpson, Eduardo Carrera, David A. Haukos, W.Carter Johnson, Charles R. Loesch, Fritz A. Reid, Scott E. Stephens, Ralph W. Tiner, Brett A. Werner, Greg S. Yarris

Natural Resource Management Faculty Publications

This paper summarises discussions by invited speakers during a special session at the 6th North American Duck Symposium on wetland issues that affect waterfowl, highlighting current ecosystem challenges and opportunities for the conservation of waterfowl in North America. Climate change, invasive species, U.S. agricultural policy (which can encourage wetland drainage and the expansion of row-crop agriculture into grasslands), cost and competition for water rights, and wetland management for non-waterfowl species were all considered to pose significant threats to waterfowl populations in the near future. Waterfowl populations were found to be faced with significant threats in several regions, including: the Central …

Scale-Up And On-Line Monitoring Of Gas-Solid Systems Using Advanced And Non-Invasive Measurement Techniques, Muthanna H. Al-Dahhan, Shreekanta Aradhya, Faraj Zaid, Neven Ali, Thaar Aljuwaya

Chemical and Biochemical Engineering Faculty Research & Creative Works

Industry relies on gas-solid systems for numerous processes. Flow dynamics play an important role in achieving the desired results. The present study proposes, validates and demonstrates a novel mechanistic scale-up approach based on maintaining similar radial profile or cross sectional distribution of gas holdup in two different gas-solid systems in order to achieve hydrodynamics similarity using advanced measurement techniques. This new methodology for scale-up and design has been implemented on gas-solid spouted bed which has been used for drying, granulation and coating. The development can be extrapolated to other gas-solid systems encountered in phosphate processes.

Adaptive Resonance Theory And Diffusion Maps For Clustering Applications In Pattern Analysis, Donald C. Wunsch, David J. Morris, Rui Xu

Electrical and Computer Engineering Faculty Research & Creative Works

Adaptive Resonance is primarily a theory that learning is regulated by resonance phenomena in neural circuits. Diffusion maps are a class of kernel methods on edge-weighted graphs. While either of these approaches have demonstrated success in image analysis, their combination is particularly effective. These techniques are reviewed and some example applications are given.