Mechanical Engineering Commons^™

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 …

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 …

Investigation On Ti6al4v-V-Cr-Fe-Ss316 Multi-Layers Metallic Structure Fabricated By Laser 3d Printing, Wei Li, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, William J. Seufzer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Joining titanium alloy and stainless steel is becoming an urgent need since their outstanding mechanical properties can be utilized integratedly. However, direct fusion joining of Ti6Al4V to SS316 can cause brittle Ti-Fe intermetallics which compromise join bonds’ mechanical properties. In this research, Laser 3D Printing was applied to explore a new Ti6Al4V to SS316 multi-metallic structure. A novel filler transition route was introduced (Ti6Al4V → V → Cr → Fe → SS316) to avoid the Ti-Fe intermetallics. Two experimental cases were performed for comparison to evaluate this novel route’s effect. In the first case, SS316 layer was directly deposited on …

Development Of A Multiphase Photon Monte Carlo Method For Spray Combustion And Its Application In High-Pressure Conditions, Somesh Roy, Jian Cai, Michael F. Modest

Mechanical Engineering Faculty Research and Publications

In this work the development of a multiphase photon Monte Carlo (PMC) method with a focus on resolving radiative heat transfer in combustion simulations is presented. The multiphase PMC solver can account for description of participating media in both Lagrangian and Eulerian frameworks. The solver is validated against exact solutions in several one-dimensional configurations. The developed solver is then applied to Diesel spray combustions, where liquid spray droplets are assumed to be cold, nonemitting, large, and isotropically scattering. Several formulations for radiative properties of the Diesel spray are first explored. The PMC solver has then been coupled with the multiphase …

An Innovative Fuzzy Backstepping Sliding Mode Controller For A Tri-Rotor Unmanned Aerial Vehicle, Shiqian Wang, Jingjuan Zhang, Qian Zhang, Chaoying Pei

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The dynamical model of a Tri-Rotor Unmanned Aerial Vehicle (UAV) is presented in this paper. The Tri-Rotor has three rotors with two fixed-pitch propellers and a tiltable propeller to control the yaw displacement. The model is obtained via the Newton–Euler approach and a nonlinear control strategy called fuzzy backstepping sliding mode control is proposed for the attitude stabilization and altitude tracking of the vehicle. The designed controller consists of a backstepping sliding mode controller and a fuzzy logic controller. For the problem of determining the backstepping sliding mode control coefficients, an optimization method of gradient descent algorithm has been used. …

Design And Analysis Of Compressed Air Power Harvesting Systems, Zachary James Sadler

Theses and Dissertations

Procedure for site discovery, system design, and optimization of power harvesting systems is developed with an emphasis on application to air compressors. Limitations for the usage of infrared pyrometers is evaluated. A system of governing equations for thermoelectric generators is developed. A solution method for solving the system of equations is created in order to predict power output from the device. Payback analysis is proposed for determining economic viability. A genetic algorithm is used to optimize the power harvesting system payback with changing quantities and varieties of thermoelectric generators, as well as the back work put into cooling the thermoelectric …

Museum Wave Tank Design, David James Streng, Lisa Michelle Dischinger, John Frederick Niemoller

Mechanical Engineering

The Santa Maria Discovery Museum would like to add a tsunami wave tank to be one of their demonstrations. The wave tank needs to draw the attention of their young crowd and be educationally informative about the shapes and effects of waves. As this is a museum demonstration for children, the structure, user interface, and wave making mechanism must be durable.

We are a senior project team from California Polytechnic State University that worked on this project with Allan Hancock College and Stanford University. We created waves by rapidly moving a plunger vertically in the water column. This project allows …

Thermal-Fluid Dynamic Model Of Luge Steels, Brandon Stell

Master's Theses

Luge is an Olympic sport in which athletes ride feet-first on sleds down an ice-covered track. Competitors spring from the starting position and accelerate their sled by paddling with spiked gloves against the ice surface. Once the Luger leaves the starting section, their downhill motion is solely propelled by the effects of gravity. Athletes compete, one after the other, for the fastest time. Runs can differ by as little as a thousandth of a second, meaning that every minor sled adjustment, change of line choice, and shift of body position is critical. In the past, the sport of Luge has …

Single Tower Crane Allocation Models Using Ant Colony Optimization, Carlos Abelardo Treviño

Theses and Dissertations

The construction industry greatly benefits from the utilization of heavy machines and equipment to accomplish successful projects. Tower cranes, in specific, have a crucial role in the transportation of material loads across the site. Because these machines are fixed to the ground, it is essential for planners and managers to position them in a location that provides the most efficient transfer of materials possible. This is commonly known as the tower crane allocation problem, and many researchers have attempted to optimize the tower crane location using mathematical, artificial intelligence, and simulation approaches. However, many works from the literature contain critical …

Development Of An Insulated Solar Electric Cooker (Isec) With Thermal Storage For Use In Developing World Countries, Amanda Gyokery, Spencer W. Davis, Kyle Henry Smit

Mechanical Engineering

According to the World Health Organization, about half of the world’s population uses biomass stoves to cook their meals. However, biomass fires can be dangerous. Unattended biomass fires and indoor air pollution are responsible for an estimated 600,000 deaths annually and the creation of approximately 4 million instances of chronic disease. They also release CO2 and other pollutants into the air, and require the families to gather enough material to keep it burning (WHO 2017). Although cleaner cooking technology seems like a clear solution, often families are either unwilling to change how they cook food or are unable to afford …

The Effects Of Exhaust Vent Location On Thermal Comfort Inside The Residential Buildings Equipped With An Evaporative Cooling System, Armin Saraei

UNLV Theses, Dissertations, Professional Papers, and Capstones

Inlet and outlet conditions, Including size and location, have significant effects on the air distribution, temperature, humidity and thermal comfort in the buildings. In the current study, various strategies are presented for exhaust air vents and the effects of inlet and outlet vents locations are evaluated on providing thermal comfort in the residential and industrial buildings. To provide thermal comfort, three key factors need to be investigated based on ASHRAE standard 55- 2013 as follows: Comfort Zone, Thermal Sensation and Draft Rate. Flow distribution is studied as well in order to investigate the strategies, which make more vorticity in the …

Design Of Metal Oxides/Metal Sulfides For The Improvement Of Sodium Ion Batteries, David E. Flores

Theses and Dissertations

Herein, the improvement in performance for sodium ion batteries (NIBs) is discussed from available literature and work conducted in the laboratory setting to demonstrate the ability of sodium to perform in the world of energy storage. The reason that sodium is being explored as an alternative to Lithium in energy storage devices is because of the potential depletion of the lithium in the world causing lithium prices to surge. Researchers show that many Sn, Sb, Ge, and other composites perform well as anode materials within NIBs. The research conducted in the dissertation applies the Forcespinning method to produce fibers for …

Study Of Latent Heat Thermal Energy Storage Systems For Concentrated Solar Power Plants, Hermes Chirino

Theses and Dissertations

Concentrated Solar Power (CSP) using phase change material (PCM) as the storage medium in the Thermal Energy Storage (TES) system is a promising technology for large scale utilization of solar thermal energy because heat latent heat thermal energy storage (LHTES) systems can store more energy as the latent heat during the melting process.

This study analyzes the different dimensionless parameters from the 1-D transient enthalpy-based mathematical model used to simulate the heat transfer and flow within the LHTES system. These dimensionless parameters are varied and analyzed with the main objective of increasing thermal energy storage efficiency and exergy efficiency of …

Effect Of Processing Parameters On The Electrochemical Performance Of Forcespun Metal Oxide/Carbon Composite Fibers For Li-Ion Batteries, Howard A. Campos

Theses and Dissertations

Metal oxides have been gaining interest as electrode materials for rechargeable Li-ion batteries due to various properties including low cost, low toxicity, and high theoretical capacity. In this research work the effect of two different metal oxide/carbon fiber composites, Fe3O4/C and ZnO/C, on the electrochemical performance for Li-ion batteries will be explored. This is also the first time that results are reported, to the best of our knowledge, of these fiber composites through the Forcespinning ® method. Scanning electron microscopy (SEM), Energy-Dispersive X-ray Analysis (EDS), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and electrochemical analysis were used to investigate …

Model Predictive Power Management Of A Hybrid Electric Propulsion System For Aircraft, Tyler J. Wall

Masters Theses

This work presents the switched optimal power flow control for an aircraft with a hybrid electric propulsion system. The propulsion system is a switched system that operates in either of two modes: (i) battery discharging and electric motor propelling and (ii) battery charging and electric motor generating. The aircraft model and components that form the hybrid propulsion system are modeled as either an algebraic power source/sink or as a dynamic model with appropriate power and state interconnections. With the system model defined, a model predictive control power management strategy is set fourth which minimizes a performance index that includes altitude …

A Globally Stable Attractor That Is Locally Unstable Everywhere, Phanindra Tallapragada, Senbagaraman Sudarsanam

Publications

We construct two examples of invariant manifolds that despite being locally unstable at every point in the transverse direction are globally stable. Using numerical simulations we show that these invariant manifolds temporarily repel nearby trajectories but act as global attractors. We formulate an explanation for such global stability in terms of the ‘rate of rotation’ of the stable and unstable eigenvectors spanning the normal subspace associated with each point of the invariant manifold. We discuss the role of this rate of rotation on the transitions between the stable and unstable regimes.

Development Of A Rotordynamic Signal Processing Matlab Interface And A Two-Disk Rotor Model, David L. Baker

Master's Theses

Using MATLAB and a National Instruments data acquisition card, a signal processing program meant to monitor the behavior of rotordynamic systems in real-time was developed and tested. By using traditional analysis methods in this field of engineering, commonly desired data representations such as bode, polar, orbit, full spectrum plots were able to be produced to a very high accuracy. Additional capabilities offered by this application are slow roll compensation, synchronous and sub-synchronous filtering, and true three dimensional plotting. The verification of this program was done by comparing the results to the ones acquired with Bently Nevada’s “Automated Diagnostics for Rotating …

Me-Em Enewsbrief, July-December 2017, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

Towards Green Building: Energy Efficient Roof System For Buildings, Dhruv Sangal

Theses and Dissertations

The present work focusses on investigating the thermal performance of different energy efficient roof systems for buildings for different climates. Buildings constitutes about 40 percent of total energy consumed by United States, and previous research shows that 20 percent of the building cooling load comes through ceiling of a building. Thus, it is important to analyze different energy efficient roof systems which can help in reducing building cooling and heating load. The present study focusses on three technologies – green roof, radiant barriers and photovoltaics. To analyze the performance of these systems, a detailed energy based mathematical model were developed …

An Obstacle Avoidance System For The Visually Impaired Using 3-D Point Cloud Processing, Evan Justin Taylor

Theses and Dissertations

The long white cane offers many benefits for the blind and visually impaired. Still, many report being injured both indoors and outdoors while using the long white cane. One frequent cause of injury is due to the fact that the long white cane cannot detect obstacles above the waist of the user. This thesis presents a system that attempts to augment the capabilities of the long white cane by sensing the environment around the user, creating a map of obstacles within the environment, and providing simple haptic feedback to the user. The proposed augmented cane system uses the Asus Xtion …

Modeling Acoustic Microfluidic Phenomena In Unconventional Geometries, Andrew Ledbetter

McKelvey School of Engineering Graduate Student Theses & Dissertations

In this work, the performance of a piezoelectrically-actuated ultrasonic droplet generator is analyzed by modeling the harmonic response of a two-dimensional representation of the device cross-section. Observed vibrational and acoustic resonances provide insight into optimal design conditions to achieve efficient, robust droplet ejection. Numerical simulations highlight the importance of the coupled electrical and mechanical behavior of the resonator assembly and show that elastic modes can effectively amplify or dampen acoustic modes within the fluid chamber. Experimentally-validated modeling results guide development of an optimization strategy to further improve device performance. In addition, the standing acoustic field that is the focus of …

A Comparison Between Self-Cleaning Properties Via Rolling Droplets And Condensation On Superhyrophobic Surfaces, David Leland Miller

Theses and Dissertations

Superhydrophobic (SH) surfaces are super water repellent surfaces on which a droplet of water will bead up like a marble and roll off the surface with minimal tilting of the surface. This is caused by the combination of a hydrophobic coating and a rough surface structure. To achieve thermodynamic stability, surface tension of the water pulls the droplet into this shape to minimize the contact area between the droplet and the surface. This creates a high contact angle (CA) between the droplet and the surface and a low sliding angle (SA) of which the droplet begins to roll off the …

Microstructural Evaluation Of Hydrogen Embrittlement And Successive Recovery In Advanced High Strength Steel, Quentin Scott Allen

Theses and Dissertations

Advanced high strength steels (AHSS) have high susceptibility to hydrogen embrittlement, and are often exposed to hydrogen environments in processing. In order to study the embrittlement and recovery of steel, tensile tests were conducted on two different types of AHSS over time after hydrogen charging. Concentration measurements and hydrogen microprinting were carried out at the same time steps to visualize the hydrogen behavior during recovery. The diffusible hydrogen concentration was found to decay exponentially, and equations were found for the two types of steel. Hydrogen concentration decay rates were calculated to be -0.355 /hr in TBF steel, and -0.225 /hr …

Eigenblades: Application Of Computer Vision And Machine Learning For Mode Shape Identification, Alex W. La

Theses and Dissertations

On August 27, 2016, Southwest Airlines flight 3472 from New Orleans to Orlando had to perform an emergency landing when a fan blade separated from the engine hub and destroyed the cowling and punctured the fuselage. Initial findings from the metallurgical examination conducted in the National Transpiration Safety Board Materials Laboratory found that the fracture surface of the missing blade showed curving crack arrest lines consistent with fatigue crack growth. Fatigue is often cause by resonate vibrations. Modal analysis is a method that can model the natural frequencies and bending modes of turbomachinery blades. When performing modal analysis with finite …

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 …

Nitrogen Doped Carbon Nanofibers Derived From Water-Soluble Precursors, Lee Cremar, Ben Jones, Nicole Martinez, Gustavo Mejia, Hilario Cortez, Edgar Muñoz, Rocío Nava, Karen Lozano

Mechanical Engineering Faculty Publications

Nitrogen doped carbon fibers were synthesized from polyvinyl alcohol (PVA), a water soluble precursor. The PVA fine fibers were first developed by centrifugally spinning an aqueous based solution using Forcespinning® technology. The precursor fibers were then exposed to sulfuric acid vapors to partially carbonize and stabilize the fibers for further heat treatment. For nitrogen doping, the fibers were exposed to two different heat treatment routes. One was under a nitrogen atmosphere at 850°C followed by exposure to ammonia gas at 500°C. The second route consisted of heating the treated fibers in pure ammonia gas only, up to 850°C. Both heating …

Temporal Transformation Of Barrier Islands A Round Nakdong Estuary, Sukzun Youn

Theses and Dissertations

The Nakdong Estuary system near Busan, South Korea consists of dynamic shorelines characterized by morphological transformations that result from both natural disasters (typhoons and flooding) and construction projects (Nakdong Estuary Dam, gates in the West Nakdong River and Busan New-ports). This study aims to synthesize existing data for tides, waves, bathymetry and meteorological data obtained from a variety of institutions with the objectives of (1) identifying and ranking major factors that influence morphological transformations and (2) determining how these factors influence morphological change over time. These objectives were met by analyzing patterns of flow and sediment transport using Center Point …

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 …