Engineering Commons^™

A Comparative Study Of Wooden And Hyrbid Composite Crossarms Of An Electric Utility Pole, Rohit Avadhani

Mechanical and Aerospace Engineering Theses - Archive

Most of the cross arms in the country are made from wood. Wood, although easily accessible, has its own defects. Environmental effects which includes the expansion and contraction of wood over the years which will disrupt its structural integrity, the presence of termites and other insects which dig into wood and destroy it from the inside, Materials wastage when it comes to improving the structural strength by increasing the cross-sectional thickness and height The replacement of wood with composites seems like a logical idea and also a solution to most of the problems. The applications of composites in our day …

Effect Of Solder Voids And Distance To Neutral Point (Dnp) On Sjr Of Wcsp Under Reflow Condition And Thermal Cycling, Aniruddha Doiphode

Mechanical and Aerospace Engineering Theses - Archive

Since the introduction of Chip Scale Packages (CSP’s) in the early 2000s, they have become one of the biggest packaging trends in recent history. There are currently over 50 different types of CSP’s available throughout the industry and the numbers are increasing almost daily. Wafer Level Chip Scale Package’s (WCSP) is kind of CSP’s used widely due to its small form factor which offers efficient use of limited space and miniaturization of the electronic device. On the other hand, small form factor typically incurs greater initial cost in product design and development. In an electronic device, it is equally important …

Strength And Damage Prognosis Of Adhesive Bond And Inter-Ply Hybrid Composites Based On Dielectric Properties, Priyanshu K. Banerjee

Mechanical and Aerospace Engineering Theses - Archive

Composite materials have found their applications in a wide range of industries particularly in the aerospace and automotive sectors. This is because they are comparatively light-weight and provide a much better corrosion and wear resistance as compared to other ceramics and metals. Adhesive bonding can be used to improve the stress distribution between these composite materials. Moreover, adhesive bond decreases the weight and concentration of stresses in the structure. Broadband Dielectric Spectroscopy, BbDS is a robust tool used for analyzing the dielectric properties of a polymer composite. This method can be used to monitor the curing process of the specimen. …

Multiphase Flow Modeling And Analysis Of Phased Filling Process For Pulsed Detonation Engine, Nirmal Kumar Umapathy

Mechanical and Aerospace Engineering Theses - Archive

Filling of reactants into a pulsed detonation engine (PDE) should be carried out quickly because any lengthening of the fill time will lead to an increased cycle time. The fill process and, the purge process constitutes a large proportion of time in a cycle. The purpose of this research was to improve the time of fill by implementing various injection geometries in two injection schemes with five different premixed stoichiometric fuel-air mixture injected at wide range of velocity. The different configurations examined were end wall injection, side wall injection with ports angled and normal to the flow direction and staggered …

Virtual Reality And Augmented Reality Applications, Tuan Ho

Electrical Engineering Dissertations - Archive

Virtual Reality (VR) and augmented reality (AR) are the emerging fields of research. VR enables the immersive, being-there feelings of the viewers in a recorded or virtual environment, while AR enhances the real-world perception with the aid of an electronic device. On the VR part, this thesis introduces the novel 360-degree video stitching algorithms for dual-fisheye lens cameras, which are compact and affordable. On the AR section, this work presents a new approach in compressing the 3-dimensional point cloud models that are used in free view-point sports and tele-immersive applications.

An Investigation Of Topology Optimization For Coupled Thermo-Structural Loading For Additive Manufacturing, Vaibhav Shankar Gaikwad

Mechanical and Aerospace Engineering Theses - Archive

This work investigates the ability of topology optimization methods to design multifunctional components with coupled thermo-structural loading for fabrication with additive manufacturing technologies. Topology Optimization is a mathematical approach developed to perform design optimization with the purpose of reducing material usage, while maximizing the structural and thermal performance, in accordance to specific design constraints. Additive manufacturing provides the capability to create internal structures and complex surfaces developed by topology optimization that would not be possible to produce by conventional manufacturing. The more structurally efficient configuration generated by topology optimization and fabricated with additive manufacturing can result in components with improved …

Numerical Study Of Droplet Evaporation, Ritul Gandhi

Mechanical and Aerospace Engineering Theses - Archive

Droplet evaporation plays a vital role in various engineering fields such as air/fuel premixing, inkjet printing and many more. The high rate of power dissipation from the integrated circuits and chips of electronic devices creates a need for cooling it to achieve their optimal functionality. The high rate of cooling can be achieved by thin film evaporation of water by phase change as compared to the air cooling methods. Therefore, the study of droplet evaporation is necessary to understand the underlying physics and effects of different parameters on cooling performance. Numerical study of droplet evaporation has been done by using …

Dc-To-Dc Buck Converter, Kyle Christopher Roman

Electrical Engineering

The growth of sustainable energy requires many components to work in harmony creating one efficient and effective system. Sustainable energy generation that produces a DC current varying in voltage requires a subsystem to convert voltage to a practical and usable value. The DC to DC Buck converter converts high DC solar generated voltage to a 12V output. This Modular -Level power electronic (MLPE) device performs as a solar charge controller for small lithium ion batteries. Fluctuating voltage levels generated by Photovoltaic cells makes the solar controller a critical part of the solar system. Regulating the DC voltage allows safe and …

Dual Method Headphone Amplifier, Joseph S. Gross, Timothy P. Murphy

Electrical Engineering

Many high impedance headphones underperform their full potential when directly connected to the audio source. Amplifiers boost the audio signal and provide the headphones with sufficient power to ensure their maximum performance. The invention of transistors caused vacuum tube implementation to decline, leaving many audiophiles unsatisfied with the transistor’s sound signature. Vacuum tubes and transistors both amplify signals, however the distinct “tube sound” has vanished.

We have designed and created a product where the user selectively switches between solid-state transistor and tube amplification to compare the sound signatures of each amplification method. The ability to switch between the solid-state and …

A Study Of Manganese And Cobalt Incorporated Nickel Oxide Based Core-Shell Magnetic Nanoparticles, Samiul Hasan

Graduate Theses/Dissertations

The synthesis along with the structural and magnetic properties of manganese (Mn) and cobalt (Co) -incorporated nickel oxide (NiO) inverted core-shell nanoparticles (CSNs) were investigated. The primary objective of this study was to determine the effect of substitution of nickel (Ni) by transition metal ions (Mn²⁺/Co²⁺) in affecting the magnetic properties of the resultant CSNs. The core of the CSNs is comprised of NiO and the shell constitutes a Ni_x(Mn/Co)_1-xO phase. The synthesis of the CSNs was accomplished in two steps: first, NiO nanoparticles were synthesized using a thermal decomposition method. In …

Block Copolymer Nanostructures For Inorganic Oxide Nanopatterning, Krishna Pandey

Graduate Theses/Dissertations

Self-assembled nature of block copolymer (BCP) makes them ideal for emerging technologies in nanometer scale. The micro phase separation between two or more dissimilar polymer blocks of BCP leads to uniform periodic nanostructures of different domains of dimension in the range of 5-100 nm, good for the development of emerging microelectronic and optoelectronics devices. Molecular weight and chain architecture of each blocks govern the morphology evolution; gives different structure like spherical, micelles, lamellae, cylindrical, gyroid etc. The morphology evolution of BCP nanostructure also depends on different external factors as well. In the first work of this thesis, three external factors …

Monitoring And Anticipating The Convergence Of Lighting Control Strategies, Nina Chaichi, Tugrul Unsal Daim

Engineering and Technology Management Faculty Publications and Presentations

IPC co-classification in conjunction with cross impact analysis has been used to identify technology convergence and its strength over specific period of time. In this study, we tried to monitor the convergence of lighting control strategies which yields energy efficiency from 2009 to 2013. Also, we tried to anticipate the trend of impacts for near future. We take new approach to utilize detailed information including rate of change of co-classified patents, number of patents in each class, and convergence strength between two classes over time and build possible scenarios to anticipate the convergence trend. In our new approach, convergence strength …

Improving The Effectiveness Of Fuzzy Front End Management: Expanding Stage-Gate Methodologies Through Agile, Aruna Bhatia, Juchun Cheng, Sadaf Salek, Vidhi Chokshi, Antonie J. Jetter

Engineering and Technology Management Faculty Publications and Presentations

More now than ever before, product development has become more challenging and complex with all the globalization around business today. Understanding the requirements of unfamiliar markets can be very challenging for organizations trying to speed-up their innovations. Also with the advent of globalization there is pressure on everyone to perform better and roll out new products in the market. The fuzzy front end process is very dynamic and unstructured process. By taking advantage of the key characteristics of Agile and Stage-Gate model, an Integrated Agile- Stage- Gate Hybrid model was developed which could help in improving the effectiveness of the …

Optimized Thruster Allocation Utilizing Dual Quaternions For The Asteroid Sample Return Mission (Osiris-Rex), Asher Smith

Doctoral Dissertations and Master's Theses

As spacecraft require higher positional accuracy from the attitude control systems, new algorithm developments, along with sensor and actuator resolution and range improvements are necessary to achieve the desired science accuracies. For agile 6-Degrees of freedom (6-DOF) spacecraft with redundancy, the actuators are usually oversized or overpopulated to meet the desired slew requirements. Currently, most spacecraft utilize an over-actuated thruster system to produce 6-DOF control. This thesis presents a simulation of the OSIRIS-REx mission during the descent phase to the asteroid Bennu, with a focus on utilizing dual quaternion dynamics and a newly developed thruster allocation method. The dual quaternion …

Low-Cost Wearable Head-Up Display For Flight General Aviation, Pavan K. Chinta

Doctoral Dissertations and Master's Theses

A low-cost wearable Commercial-off-The-Shelf (COTS) Augmented Reality (AR) Head-Up Display (HUD) system is designed, successfully reduced to practice, and flight tested. The system is developed based on the need for a technology that improves loss-of-control (LOC) safety in the General Aviation (GA) sector. The accuracy of the flight-path based system is determined to be within a degree of the truth source. The repeatability of the data from the COTS system is excellent. A complementary filter is proposed for air data flow angles and successfully flight tested for straight and level flight, dynamic maneuvering, and atmospheric turbulence, provided that a reasonably …

Mechanical And Electrical Characterization Of Carbon Fiber/Bucky Paper/Zinc Oxide Hybrid Composites, Suma Ayyagari

Doctoral Dissertations and Master's Theses

The quest for multifunctional carbon fiber reinforced composites (CFRPs) expedited the use of several nano reinforcements such as zinc oxide nanorods (ZnO) and carbon nanotubes (CNTs). Zinc oxide is semi-conductor with good piezoelectric and pyroelectric properties. These properties could be transmitted to CFRPs when a nanophase of ZnO is embedded within CFRPs. In lieu of ZnO nanorods, Bucky paper comprising mat of multiwall-carbon nanotubes (MWCNTs) could be sandwiched in-between laminae to construct a functionally graded composite with elevated electrical and thermal conductivities. In this study, a low temperature ( 90_C) hydrothermal synthesis method was utilized to grow ZnO nanorods on …

Computational Investigation Of The Biomechanics Of Babywearing In Regards To Developmental Dysplasia Of The Hip, Gaurav Girish

Doctoral Dissertations and Master's Theses

Developmental Dysplasia of the Hip (DDH) is a congenital condition where an infant’s hip socket is either loose or otherwise unstable. DDH causes a joint instability where the femoral head is not properly situated inside the acetabulum. Etiology of the condition is in part congenital and developmental, with a difference of DDH prevalence between ethnicities. Incidence of DDH is also in some part dependent on cultural practices and activities of the mother and child. The exact nature of this cultural incidence is not clearly understood. A computational approach is hypothesized to identify the impact of babywearing position on the healthy …

Aviation Propulsive Lithium-Ion Battery Packs State-Of-Charge And State-Of-Health Estimations And Propulsive Battery System Weight Analysis, Jingsi Lilly

Doctoral Dissertations and Master's Theses

Aviation propulsive battery pack research is in high demand with the development of electric and hybrid aircraft. Accurate inflight state-of-charge and state-of-health estimations of aviation battery packs still remain challenging. This thesis puts efforts on estimating the state-of-charge, state-of-health, and remaining energy of a lithium- ion propulsive battery pack with a recursive least squares based adaptive estimator. By reading the system measurements (discharging currents and terminal voltages) with persistent excitation, the proposed estimator can determine the present internal parameters of the battery cells and further interpolate them into state-of-charge, state-of-health, and the remaining energy information. The validation results indicate that …

Aerodynamic And Performance Analysis Of A Morphing Helicopter Rotor System, Vinay Gopal Krishnan

Doctoral Dissertations and Master's Theses

The purpose of this study was to investigate the effect of rotor morphing, specifically variable rotor speed and variable blade twist, on various parameters such as the distribution of angle of attack, lift, power, thrust and/or other metrics describing the performance of a helicopter rotor. A MATLAB based blade element theory model was developed and executed for different flight conditions. The model was validated against the flight test data of a UH-60. Effects on power, lift to drag ratio and rotor drag from variations in blade twist, rotor speed, rotor radius and blade chord was analyzed. Morphing cases were applied …

Design Of Flight Control Laws For A Novel Stratospheric Dual-Aircraft Platform, Cindy Nshuti

Doctoral Dissertations and Master's Theses

Dual-aircraft platform (DAP) is a novel concept that features two glider-like unmanned aerial systems (UAS) tethered via a thin adjustable cable allowing them to sail back-and-forth, without propulsion, using vertical wind shear. DAP offers the potential of a low-cost atmospheric satellite. This thesis presents the results of an initiative to demonstrate this novel flight concept through modeling, simulation, and flight testing at Embry-Riddle Aeronautical University (ERAU). A realistic simulation environment, described herein, was developed to support the development and testing of flight control systems. This environment includes nonlinear aerodynamic models for the aircraft, a multi-element cable dynamics model, propeller-motor thrust …

A Study On The Control, Dynamics, And Hardware Of Micro Aerial Biomimetic Flapping Wing Vehicles, Siara Hunt

Doctoral Dissertations and Master's Theses

Biological flight encapsulates 400 million years of evolutionary ingenuity and thus is the most efficient way to fly. If an engineering pursuit is not adhering to biomimetic inspiration, then it is probably not the most efficient design. An aircraft that is inspired by bird or other biological modes of flight is called an ornithopter and is the original design of the first airplanes. Flapping wings hold much engineering promise with the potential to produce lift and thrust simultaneously. In this research, modeling and simulation of a flapping wing vehicle is generated. The purpose of this research is to develop a …

Distributed Model Predictive Control Of Power Converters In Microsrids Under Different Modes Of Operation, Riyadh Toman Thahab Toman

Dissertations

Microgrids consist of many distributed energy sources (DERs) and the overall system is viewed as a number of subsystems. In this work, a finite control set model predictive control is proposed to control power converters in both grid and island modes of operation of the microgrid. Each subsystem is assigned a local controller that relies on measurements of common coupling point (PCC) and/or terminal quantities to provide accurate regulation of current or voltage components. This meets the local objective of each subsystem and contributes to the global objective of the microgrid.

In the first part of the work, a microgrid …

Understanding The Long-Term Changes In Hydrologic Processes On A Watershed Scale Due To Climate Variability And Change, Chao Chen

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the past century, the population explosion and economic development have resulted in global warming, which has raised a series of concerns, such as sea-level rise, food security, and water resources management. The water flow patterns and features experience both short-term and long-term changes in responses to the changes in the hydrologic processes and meteorologic conditions. On a watershed scale, it is crucial to understand, quantify, and attribute the influences of climate change on the local water resources system. Such understanding can be of great help to undertake local water management tasks, such as flood control, reservoir operation, ecosystem services, …

Radiative Contour Mapping Using Uas Swarm, Zachary Cook

UNLV Theses, Dissertations, Professional Papers, and Capstones

The work is related to the simulation and design of small and medium scale unmanned aerial system (UAS), and its implementation for radiation measurement and contour mapping with onboard radiation sensors. The compact high-resolution CZT sensors were integrated to UAS platforms as the plug-and-play components using Robot Operation System. The onboard data analysis provides time and position-stamped intensities of gamma-ray peaks for each sensor that are used as the input data for the swarm flight control algorithm. In this work, a UAS swarm is implemented for radiation measurement and contour mapping. The swarm of UAS has advantages over a single …

Investigation Of Setting Time And Compressive Strength Of Ready-Mixed Concrete Blended With Returned Fresh Concrete, Negasi Niguse Gebremichael

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Center for Sustainable Transportation Infrastructure (CSTI), in its 2012 study, estimated that out of all the concrete leaving the plant, between 2% and 7% of concrete returns to the plant unused as a returned fresh concrete (RFC). Disposal of both the truck wash water and RFC is a growing concern for the industry. Most industry personnel contacted during the investigation, agree that reusing is superior to recycling of this substantial RFC economically and environmentally. This study will determine if the reuse of RFC in subsequent batches compromises the quality of newly blended concrete.

The effect of RFC on fresh …

Numerical Characterization Of The Flow Field And Heat Transfer Inside The Receiver Of A Parabolic Trough Solar Collector Carrying Supercritical Co2, Samad Gharehdaghimollahajloo

UNLV Theses, Dissertations, Professional Papers, and Capstones

The aim of this research is to provide a detailed numerical analysis of flow field and heat transfer inside the heat collecting element of a parabolic trough collector. The parabolic trough collector is used as the boiler in a direct Super Critical Carbon Dioxide (S-CO2) Brayton cycle.

A single collector is modeled and analyzed with different inlet conditions. The working fluid is supercritical since its pressure is increased to above critical pressure in the compressor while its temperature reaches 300 °C after passing through the recuperators and before entering the solar field. For the first time, this research considers both …

Controlled Electrochemical Reduction Of Gold And Palladium Metal Precursors In Polyaniline, Nicole Goodwin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Polyaniline (PANI) has been extensively studied due to its unique electrochemical properties. The conjugated polymer is conductive with high chemical stability below 100°C, mechanical strength, and large surface area. The applications of PANI have included chemical sensing, corrosion inhibition coatings, light emitting diode and as a substrate for metal composite catalysts. Both chemical and electrochemical methods have been developed and utilized in the synthesis of PANI/metal composites. The simultaneous reduction of aniline and metal precursor produces a composite of PANI encapsulated metal, reducing the active surface area available for catalysis. Alternatively, chemical reduction of the metal precursor into preformed PANI …

Evaluating The Chemical And Biological Stability Of Finished Waters Blended For Direct Potable Reuse In A Simulated Distribution System, Assumption Grimaldi

UNLV Theses, Dissertations, Professional Papers, and Capstones

This work evaluated the impacts of blending several different high grade recycled waters with conventional source waters for direct potable reuse (DPR) applications. Bench-scale laboratory tests were conducted for recycled water-source water blends from four participating facilities that have either considered adopting DPR or have already implemented DPR as a feasible approach to overcome water scarcity. The chemical and biological stability of the finished waters was investigated after pipe rig incubation to simulate the quality of blended waters that had aged in a potable water distribution system. The effects of blend ratio, reclaimed water treatment, and source water quality were …

Surface And Interface Characterization Of Solution-Processed Metal Oxides And Pedot:Pss Using Photoelectron Spectroscopy, Lynette M. Kogler

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solution-processed materials are appealing for use in printable electronics as a means to lower production costs, but precise control of the process is crucial for achieving the desired properties in the final materials and their interfaces. Electronic interface properties depend on both the involved materials and their fabrication processes, impacting the development and commercialization of these materials. Analyzing the chemical and electronic structure of these materials, particularly at the surfaces and interfaces, is important not only for insuring that the materials have the desired properties, but also for understanding the effects of the fabrication process and how to modify properties …

Comparison Of Simulation Methods Of Single And Multi-Bit Continuous Time Sigma Delta Modulators, Benju Koirala

UNLV Theses, Dissertations, Professional Papers, and Capstones

Continuous time Sigma Delta Modulators (CT ΣΔMs) are a type of analog to digital converter (ADC) that are used in mixed signal systems to convert analog signals into digital signals. ADCs typically require antialiasing filter; however antialiasing filters are inherent in CT ΣΔMs, and therefore they require less circuitry and less power than other ADC architectures that require separate antialiasing filters. As a result, CT ΣΔM ADC architectures are preferred in many mixed signal electronic applications.

Because of the mixed signal nature of CT ΣΔMs, they can be difficult to simulate. In this thesis, various methods for simulating single-bit and …