Engineering Commons^™

Assessing Interlaminar Shear Stress-Strain Curves In Tape Composites Based On The Flat-Plate Torsion Method, Gary Steven Grohman

Mechanical and Aerospace Engineering Theses - Archive

Composites are attractive for structural applications in the aerospace industry for their high strength to weight ratio, stiffness, and low density. The development and implementation of composite structures has grown rapidly through the aerospace industry exceeding our ability to characterize the material properties due to costly and time consuming test methods. The ability to fully characterize the nonlinear stress-strain relationship in the 1-3 and 2-3 principal planes up to the point of failure is extremely important for predicting failures in composites. The principal directions for composites are the fiber direction, transverse direction, and the thru thickness direction, commonly referred to …

Heat Removal Analysis Using Ntu Microscopic Theory And Experimental Fluid Testing Of Radaitors, Pumps And Fans For The Thermal Management System Of Formula Sae Electric Racecar, Shahzad Shahrukh Bulsara

Mechanical and Aerospace Engineering Theses - Archive

Formula SAE at UT Arlington has always been building well engineered race cars, further being one of the top teams in The United States. However, an electric race car being first in the fleet, cooling of electric motors played a vital role. The thermal system being significantly different from combustion cars, consists of a lower heat application. It is always favorable to maintain electronics as close to ambient temperature as compared to its counter hydro-mechanical engines. To attain the objective, a complete thermal & fluid analysis was carried out using the NTU method/ microscopic theory and experimental results associated towards …

Performance Evaluation Of Tcp Multihoming For Ipv6 Anycast Networks And Proxy Placement, Raya Alsharfa

Electronic Theses and Dissertations

In this thesis, the impact of multihomed clients and multihomed proxy servers on the performance of modern networks is investigated. The network model used in our investigation integrates three main components: the new one-to-any Anycast communication paradigm that facilitates server replication, the next generation Internet Protocol Version 6 (IPv6) that offers larger address space for packet switched networks, and the emerging multihoming trend of connecting devices and smart phones to more than one Internet service provider thereby acquiring more than one IP address. The design of a previously proposed Proxy IP Anycast service is modified to integrate user device multihoming …

Nanoscale Control Of Gap-Plasmon Enhanced Optical Processes, Chatdanai Lumdee

Electronic Theses and Dissertations

Surface plasmon resonances of metal nanostructures have been studied intensely in recent years. The strong plasmon-mediated electric field enhancement and field confinement well beyond the diffraction limit has been demonstrated to improve the performance of optical devices including ultrasensitive sensors, light emitters, and optical absorbers. A plasmon resonance mode of particular recent interest is the gap plasmon resonance that occurs on closely spaced metallic structures. In contrast to plasmon resonances supported by isolated metal nanostructures, coupled nanostructures provide additional spectral and spatial control over the plasmon resonance response. For example, the resonance frequencies of metal nanoparticle dimers depend strongly on …

Optical Propagation Of Self-Sustaining Wavefronts And Nonlinear Dynamics In Parabolic Multimode Fibers, Matthew Mills

Electronic Theses and Dissertations

The aim of this thesis is to introduce my work which has generally been focused on optical wavefronts that have the unusual property of resisting commonplace phenomena such as diffraction and dispersion. Interestingly, these special beams are found both in linear and nonlinear situations. For example, in the linear regime, localized spatio-temporal waves which resemble the spherical harmonic symmetries of the hydrogen quantum orbitals can simultaneously negotiate both diffractive and dispersive effects. In the nonlinear regime, dressed optical filaments can be arranged to propagate multi-photon produced plasma channels orders of magnitude longer than expected. The first portion of this dissertation …

Zrb2-Sic Based Ultra High Temperature Ceramic Composites: Mechanical Performance And Measurement And Design Of Thermal Residual Stresses For Hypersonic Vehicle Applications, Richard Stadelmann

Electronic Theses and Dissertations

Ultra-high temperature ceramics (UHTCs), such as ZrB2-based ceramic composites, have been identified as next generation candidate materials for leading edges and nose cones in hypersonic air breathing vehicles. Mechanical performance of ceramic composites play an important role in the ultra-high temperature applications, therefore SiC is added to ZrB2 as a strengthening phase to enhance its mechanical performance. The high melting temperatures of both ZrB2 and SiC, as well as the ability of SiC to form SiO2 refractory oxide layers upon oxidation make ZrB2-SiC ceramics very suitable for aerospace applications. Thermal residual stresses appearing during processing are unavoidable in sintered ZrB2-SiC …

Towards High-Flux Isolated Attosecond Pulses With A 200 Tw Cpa, Eric Cunningham

Electronic Theses and Dissertations

Attosecond pulses have been developed as a means for investigating phenomena that proceed on the order of the atomic unit of time (24 as). Unfortunately, these extreme ultraviolet (XUV) pulses by themselves contain too few photons to initiate nonlinear dynamics or dress states in an attosecond pump--attosecond probe scheme. As a result, most attosecond experiments thus far have featured complementary near infrared (NIR) femtosecond lasers for instigating electron dynamics. In order to access the benefits of all-attosecond measurements and open attosecond physics to new fields of exploration, the photon flux of these pulses must be increased. One way to boost …

Experimental And Numerical Study Of Endwall Film Cooling, Srikrishna Mahadevan

Electronic Theses and Dissertations

This research work investigates the thermal performance of a film-cooled gas turbine endwall under two different mainstream flow conditions. In the first part of the research investigation, the effect of unsteady passing wakes on a film-cooled pitchwise-curved surface (representing an endwall without airfoils) was experimentally studied for heat transfer characteristics on a time-averaged basis. The temperature sensitive paint technique was used to obtain the local temperatures on the test surface. The required heat flux input was provided using foil heaters. Discrete film injection was implemented on the test surface using cylindrical holes with a streamwise inclination angle of 35? and …

Thermodynamic Analysis And Optimization Of Supercritical Carbon Dioxide Brayton Cycles, Mahmood Mohagheghi

Electronic Theses and Dissertations

The power generation industry is facing new challenging issues regarding accelerating growth of electricity demand, fuel cost and environmental pollution. These challenges accompanied by concerns of energy resources becoming scarce necessitate searching for sustainable and economically competitive solutions to supply the future electricity demand. To this end, supercritical carbon dioxide (S-CO2) Brayton cycles present great promise particularly in high temperature concentrated solar power (CSP) and waste heat recovery (WHR) applications. With this regard, this dissertation is intended to perform thorough thermodynamic analyses and optimization of S-CO2 Brayton cycles for both of these applications. A modeling tool has been developed, which …

Cyclic And Impact Resistance Of Frp Repaired Poles, Zainab Mohsin

Electronic Theses and Dissertations

Sign and signal structures involved in vehicular accidents are often partially damaged, and it is possible to repair them instead of replacing them, even when the extent and severity of the damage are substantial. The replacement of these poles is costly and involves interruption for pedestrians and traffic. Therefore, some trials were performed to retrofit these poles in-situ with low cost and short time. Previous research has substantiated that the damage can decrease the strength of the these structures with increasing the dent depth and the use of externally-bonded fiber-reinforced polymer (FRP) composites are beneficial to repair them. The composite …

Post Conversion Correction Of Non-Linear Mismatches For Time Interleaved Analog-To-Digital Converters, Charna Parkey

Electronic Theses and Dissertations

Time Interleaved Analog-to-Digital Converters (TI-ADCs) utilize an architecture which enables conversion rates well beyond the capabilities of a single converter while preserving most or all of the other performance characteristics of the converters on which said architecture is based. Most of the approaches discussed here are independent of architecture; some solutions take advantage of specific architectures. Chapter 1 provides the problem formulation and reviews the errors found in ADCs as well as a brief literature review of available TI-ADC error correction solutions. Chapter 2 presents the methods and materials used in implementation as well as extend the state of the …

Inverse-Consistent Determination Of Young's Modulus Of Human Lung, Behnaz Seyfi Noferest

Electronic Theses and Dissertations

Human lung undergoes respiration-induced deformation due to sequential inhalation and exhalation. Accurate determination of lung deformation is crucial for tumor localization and targeted radiotherapy in patients with lung cancer. Numerical modeling of human lung dynamics based on underlying physics and physiology enables simulation and virtual visualization of lung deformation. Dynamical modeling is numerically complicated by the lack of information on lung elastic behavior, structural heterogeneity as well as boundary constrains. This study integrates physics-based modeling and image-based data acquisition to develop the patient-specific biomechanical model and consequently establish the first consistent Young's modulus (YM) of human lung. This dissertation has …

Agent-Based And System Dynamics Hybrid Modeling And Simulation Approach Using Systems Modeling Language, Asli Soyler Akbas

Electronic Theses and Dissertations

Agent-based (AB) and system dynamics (SD) modeling and simulation techniques have been studied and used by various research fields. After the new hybrid modeling field emerged, the combination of these techniques started getting attention in the late 1990's. Applications of using agent-based (AB) and system dynamics (SD) hybrid models for simulating systems have been demonstrated in the literature. However, majority of the work on the domain includes system specific approaches where the models from two techniques are integrated after being independently developed. Existing work on creating an implicit and universal approach is limited to conceptual modeling and structure design. This …

Catalytic Role Of Boron Nitride In The Thermal Decomposition Of Ammonium Perchlorate, Kevin Grossman

Electronic Theses and Dissertations

The decomposition of Ammonium Perchlorate (AP), a strong oxidizer used in solid rocket propellant, is widely studied in an attempt to increase the burn characteristics of propellants. Many materials have been shown to catalyze its decomposition, but little is known about the mechanism by which AP decomposition becomes catalyzed. In this study, Boron Nitride (BN) nanostructures, a material previously unknown to act as a catalyst, is studied. The decomposition reaction is studied by thermo-gravimetric analysis / differential scanning calorimetry, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The goal of this study is to …

Low Absorption Liquid Crystal Materials For Midwave Infrared, Amy Creekmore

Electronic Theses and Dissertations

Liquid crystal is an amazing class of soft matters with applications spanning from visible, infrared, millimeter wave, to terahertz. In addition to direct-view displays and projection displays, liquid crystal is also widely used in adaptive optics, tunable-focus lens, and laser beam steering. Although the visible region has well developed materials and mixtures for the vast variety of applications, the midwave infrared (MWIR) region of the electromagnetic spectrum invites much development as only a few materials have been developed with these applications in mind. Unlike visible region, the major challenge for mid-wave infrared liquid crystal is inherently large absorption loss. To …

Eece 7905/8905: Computational Science & Engineering Iii: Fluid-Structure Interaction (Syllabus), Madhusudhanan Balasubramanian

Electrical and Computer Engineering Syllabi Archive

Course Description: Multiphysics simulations are useful for modeling the behavior of coupled systems governed by two or more physical laws and their interactions. Examples are modeling of blood flow in arteries and veins, pulmonary gas exchange and transport, hydrodynamics and aerodynamics during power generation and electro-thermal-structural interface during drug delivery. Emphasis of this course is on computational modeling of fluid-structure interaction in a moving domain. Topics covered will emphasize on deriving theoretical models from physical laws and constitutive equations governing fluid-structure interaction, and developing finite element procedures for modeling fluid-structure interaction in a moving domain. PhD students registering at the …

Real Time Mission Planning, Emad William Saad, Stefan Richard Bieniawski, Riley Pigg, Paul Edward, John Lyle Vian, Paul Michael Robinette, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

The different advantageous embodiments provide a system comprising a number of computers, a graphical user interface, first program code stored on the computer, and second program code stored on the computer. The graphical user interface is executed by a computer in the number of computers. The computer is configured to run the first program code to define a mission using a number of mission elements. The computer is configured to run the second program code to generate instructions for a number of assets to execute the mission and monitor the number of assets during execution of the mission.

One-Dimensional Triple Periodic Dual-Beam Microstrip Leaky-Wave Antenna, Zi Long Ma, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

In this letter, a novel dual-beam microstrip leaky-wave antenna based on one-dimensional triple periodic (TP) structure is proposed. Through theoretical dispersion relation analysis, it is found that compared to the conventional periodic structure, TP structure has reduced the separation of space harmonics. Hence, more space harmonic modes are brought into the leaky-wave radiation region. Through proper design, m = - 1 and m = - 2 modes are excited simultaneously. Consequently, the forward and backward propagation waves of these two modes generate two radiation beams in the far-field region. At different frequencies, symmetrical and asymmetrical beam pairs are realized. It …

Numerical Simulations Of Surface Charging At The Lunar Terminator, Daoru Frank Han, Joseph J. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A full-particle particle-in-cell (PIC) simulation model is developed to perform fully-kinetic simulations of surface-plasma interactions at the lunar terminator region. This model uses a non-homogeneous immersed-finite-element (IFE) solver to calculate the electric field discontinuity (flux jump) at the plasma-surface interface and surface charging for realistic lunar surface terrain. The simulation includes all plasma species, including the solar wind electrons and ions, as well as photoelectrons with real proton-to-electron mass ratio so the kinetic properties in the mesothermal flow are resolved. We present simulation results of surface charging around a lunar hill at the lunar terminator region.

Network Attack Experimentation Using Openflow-Enabled Geni Testbed, Mani Chaitanya Gorla, Venu Madhav Kamaraju, Egemen K. Çetinkaya

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

On Robust And Secure Wireless Communication System Design Using Software-Defined Radios, Kapil Meghashyam Borle

Dissertations - ALL

This dissertation is composed of three parts: airborne multi input multi output (MIMO) communications, physical layer authentication, and software radio design for DARPA Spectrum Challenge. A common theme for the three distinct problems is the system perspective that we have adopted throughout this dissertation. Instead of considering isolated issues within these problems, we have provided a holistic design approach to the three problems and have implemented all three systems using the GNU Radio/USRP (Universal Software Radio Peripheral) platform.

In the first part, we develop a MIMO communication system for airborne platforms. MIMO communication has long been considered to be suitable …

Reliable Inference From Unreliable Agents, Aditya Vempaty

Dissertations - ALL

Distributed inference using multiple sensors has been an active area of research since the emergence of wireless sensor networks (WSNs). Several researchers have addressed the design issues to ensure optimal inference performance in such networks. The central goal of this thesis is to analyze distributed inference systems with potentially unreliable components and design strategies to ensure reliable inference in such systems. The inference process can be that of detection or estimation or classification, and the components/agents in the system can be sensors and/or humans. The system components can be unreliable due to a variety of reasons: faulty sensors, security attacks …

Characterization Of Fundamental Communication Limits Of State-Dependent Interference Networks, Ruchen Duan

Dissertations - ALL

Interference management is one of the key techniques that drive evolution of wireless networks from one generation to another. Techniques in current cellular networks to deal with interference follow the basic principle of orthogonalizing transmissions in time, frequency, code, and space. My PhD work investigate information theoretic models that represent a new perspective/technique for interference management. The idea is to explore the fact that an interferer knows the interference that it causes to other users noncausally and can/should exploit such information for canceling the interference. In this way, users can transmit simultaneously and the throughput of wireless networks can be …

Link Prediction In Dynamic Weighted And Directed Social Network Using Supervised Learning, Ricky Laishram

Dissertations - ALL

Link Prediction is an area of great interest in social network analy- sis. Previous works in the area of link prediction have only focused on networks where the links once created cannot be removed. In many real world social networks, the links should be assigned strengths; for example, the strength of a link should decrease over time, if there are no interactions between the two nodes for a long time and increase if the two nodes interact often. In this thesis we modify existing meth- ods of link prediction to apply to weighted and directed networks. The features, developed in …

A Stroke Of Shear Genius: The Development Of The Blade Bandit, Abdulrahman Hamid

Honors Theses

This thesis will document and analyze the experience of two members of the Shear Genius team, Mr. Abdulrahman Hamid and Mr. Colin Wattigney, as they worked to complete the CME Senior Capstone Project. This team, under the leadership of CEO Ethan Veazey, developed the Blade Bandit, a lawn mower blade sharpening system conceptualized by Mr. Jacob Moorhead. Ms. Kristen Gaddis, Mr. Nick Rocco, and Ms. Allie Winters were also members of Shear Genius. The team members had educational backgrounds in the realms of engineering, business and accountancy. The combination of these disciplines allowed for the simulation of a real business …

Optimization: A Perspective On Improving An Ethylbenzene Production Design, Derrick C. Marchant

Honors Theses

The goal of optimization in a chemical process or system involves improving an existing design or a combination of devices. In the case of an established process such as the ethylbenzene production process investigated here, the optimization involves improving an established process and choosing the best available case within a set of constraints that also considers maximizing the economic bottom line. An objective function must be selected for an optimization problem which defines the achievable goal. The objective function of the optimization process presented here is to minimize the estimated annual operating cost (EAOC). An EAOC takes in to account …

Thermodynamic Grain Size Stabilization Models: An Overview, Mostafa Saber, Carl C. Koch, Ronald O. Scattergood

Mechanical and Materials Engineering Faculty Publications and Presentations

Grain boundaries in a nanocrystalline microstructure produce an increase in the excess free energy of the system. Grain growth is a consequence of the thermodynamic driving force reducing this excess. Thermodynamic stabilization is an approach based on eliminating the driving force by suitable alloy additions that can produce a metastable equilibrium state at the nanoscale grain size, as opposed to kinetic stabilization where the grain growth mobility is restricted by pinning and/or drag mechanisms. The present paper reviews and compares various models proposed for thermodynamic stabilization.

Dispersion Modeling Of Nitrogen Dioxide (No2) And Fine Particulate Matter (Pm2.5) From Backup Generators At Data Centers In Prineville, Oregon, Brooke E. Harmon

Civil and Environmental Engineering Master's Project Reports

As our society becomes increasingly dependent on digital communication (e.g., social media and email) and computerized storage (e.g., digitized medical records and government documents), tech giants such as Google, Facebook, and Apple are constructing and managing an increasing number of massive Internet data centers. These data centers house a network’s most critical systems and are vital to the continuity of daily operations. Requiring as much electricity as a medium size city, data centers rely on complex auxiliary power systems to prevent disruption to service. These backup systems consist of tens of multi-megawatt diesel-powered generators that release combustion byproducts, including over …

Pushover Analysis Of Retrofitted Reinforced Concrete Buildings, Hamidreza Nahavandi

Civil and Environmental Engineering Master's Project Reports

For the past decade or more, the structural engineering profession has been using the nonlinear static procedure (NSP) or pushover analysis. Modeling for such analysis requires the determination of nonlinear properties of each component in the structure, quantified by strength and deformation capacities, which depend on the modeling assumptions. Pushover analysis is carried out for either user-defined nonlinear hinge properties or default-hinge properties, available in some programs based on the FEMA-356 such as SAP2000. While such documents provide the hinge properties for several ranges of detailing, programs may implement averaged values. In the realm of retrofitting of existing structures, few …

Dynamic Effect Of Light And Turbulence On Algal Photosynthetic Rate: A Water-Quality Model, Andres R. Rivas

Civil and Environmental Engineering Master's Project Reports

Several studies provide evidence that algal photosynthetic rates depend on various changing factors such as light attenuation, temperature, and nutrient limitation (Chapra, 1997). However, recent papers show that turbulence and photosynthetic rate dynamics is also important (Ross, 2006). In this study, the photosynthetic rate model used is the one proposed by Chapra (1997), where it depends directly on temperature, nutrient and light limitation factors. At the same time, the effect of turbulence or random-walk of algae particles in the water column was also introduced in this model. To account for this factor, the model added was that proposed by Ross …