Aerospace Engineering Commons^™

Pseudo-Spectral Methods Based Real-Time Optimal Path Planning For Unmanned Ground Vehicles, Denish Kamleshkumar Baman

Mechanical and Aerospace Engineering Theses - Archive

Real-time optimal trajectory design and tracking for autonomous ground vehicles are maturing technologies with the potential to advance mobility by enhancing time and energy efficiency in application such as indoor surveillance robots or planetary exploration rovers. Pseudo-spectral methods based trajectory generation framework provides the desired trajectory which minimizes a prescribed objective function (i.e. minimum time, acceleration, and energy) while satisfying kinodynamics and various types of constraints (i.e. obstacle avoidance and smooth turning at waypoint transitions). In this thesis cyber-physical system architecture is used for the communication between rover-vehicle and the ground station. By using optimal state and control vector from …

Board Level Solder Joint Reliability Assessment Study Of Megtron 6 Vs Fr-4 Under Power Cycling And Thermal Cycling, Jyotirmoy Denria

Mechanical and Aerospace Engineering Theses - Archive

High frequency laminates like Nelco N4000-13, Isola FR408 and Panasonic Megtron 6 packages gained popularity among the industry due to better and improved electrical performances, Improved impedance control, low moisture absorption, good thermal management. High speed laminates are extensively used in high-speed system-level interconnects like high speed network equipment, mainframes, IC testers and high frequency measuring instruments. When an electronic device is turned off and then turned on multiple times, it creates a loading condition called power cycling. The die is the only heat source causing non-uniform temperature distribution. In this paper, the solder joint reliability assessment of Megtron 6 …

Real Time And High Fidelity Quadcopter Tracking System, Tyler Mckay Hall

Computer Engineering

This project was conceived as a desired to have an affordable, flexible and physically compact tracking system for high accuracy spatial and orientation tracking. Specifically, this implementation is focused on providing a low cost motion capture system for future research. It is a tool to enable the further creation of systems that would require the use of accurate placement of landing pads, payload acquires and delivery. This system will provide the quadcopter platform a coordinate system that can be used in addition to GPS.

Field research with quadcopter manufacturers, photographers, agriculture and research organizations were contact and interviewed for information …

Whitespace Exploration, Jason Lloyd Daniel

Master's Theses

As engineering systems grow in complexity so too must the design tools that we use evolve and allow for decision makers to efficiently ask questions of their model and obtain meaningful answers. The process of whitespace exploration has recently been developed to aid in engineering design and provide insight into a design space where traditional design exploration methods may fail. In an effort to further the research and development of whitespace exploration algorithms, a software package called Thalia has been created to allow for automated data collection and experimentation with the whitespace exploration methodology.

In this work, whitespace exploration is …

Manufacturing And Instrumentation Of An Open End Compressed Air Shock Tube, Josue O. Ruiz

Master's Theses

Shock tubes have been used extensively to study shock wave structures and high speed flow features. The purpose of constructing this open end shock tube was to have the ability to produce shock waves in a laboratory setting but also understand the exit flow coming out which can be applied to future studies that are beyond the scope of this work. This undertaking would require that an open end shock tube be built and instrumented with PCB Integrated Circuit Piezoelectric (ICP) Pressure Sensor Model 113B24 that would then be connected to a PCB Model 482C05 Signal Conditioner with the purpose …

A Comparison Study Of Composite Laminated Plates With Holes Under Tension, Joun S. Kim

Master's Theses

A Comparison Study of Composite Laminated Plates with Holes under Tension

A study was conducted to quantify the accuracy of numerical approximations to deem sufficiency in validating structural composite design, thus minimizing, or even eliminating the need for experimental test. Error values for stress and strain were compared between Finite Element Analysis (FEA) and analytical (Classical Laminated Plate Theory), and FEA and experimental tensile test for two composite plate designs under tension: a cross-ply composite plate design of [(0/90)4]s, and a quasi-isotropic layup design of [02/+45/-45/902]s, each with a single, centered hole of 1/8” diameter, and 1/4" diameter (four sets …

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 Design Methodology For Continuous Fiber Additive Manufacturing Using Advanced Computer Aided Engineering Techniques, Nicholas Venter

Mechanical and Aerospace Engineering Theses - Archive

A design methodology for Continuous Carbon Fiber Additive Manufacturing (CCFAM) developed using Computer Aided Engineering (CAE) techniques takes advantage of both the mechanical strength of composite materials and the Fused Filament Fabrication (FFF) method. By performing topology optimization and Finite Element Analysis (FEA) on a load-bearing part, engineers can design much lighter optimized parts that are just as strong as those produced using FFF. This weight reduction is achieved by relying on the mechanical strength of continuous carbon fibers printed alongside a traditional thermoplastic matrix. The FFF additive manufacturing method enables the production of complex shapes, which can match the …

Effect Of Underfill Material & Gap Height On Reliability Of Low-K Large-Die Flip Chip Package Under Thermal Loading, Paul Crisanth

Mechanical and Aerospace Engineering Theses - Archive

The reliability assessment of package assembly is important to predict the performance of any microelectronic devices. Formation of fatigue cracks at the interface between the solder joint and component is the common failure occurring in widely used microelectronic devices. Lead-free solders and advanced silicon process nodes with the low-k dielectrics flip chip package are used and are facing significant reliability challenges. The mismatch of coefficient of thermal expansion (CTE) between the chip and substrate affect solder joint reliability. The underfill encapsulant packaging is widely used to improve chip device reliability. In this paper, we are studying the effect of different …

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. …

Optical Flow Method For Blood Flow Velocimetry Based On Digital X-Ray Subtraction Angiography: A Brief Review, Zifeng Yang

Mechanical and Materials Engineering Faculty Publications

Detailed blood flow information has been recognized as the key information for diagnosis of vascular diseases, such as vascular stenosis and aneurysms. Optical flow method (OFM) is an emergent technique as a tool to analyze the digital x-ray subtraction angiographic images of blood vessels to obtain the detailed blood flow distribution in vascular systems. A brief review isconstructed to discuss the status, applicability, accuracy and future direction of the optical flow technique in the physical study of vascular flow.

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 …

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 …

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 …

Aerodynamic Analysis Of Low Speed Wing Design Using Taguchi L9 Orthogonal Array, Kenneth Witcher, Ian Mcandrew, Elena Vishnevskaya

Publications

The study of aerodynamics has been preoccupied with understanding flight at increasing speeds and ultimately supersonic. Today, this pursuit has advanced the science for both Hypersonic and Transonic flight to near Mach 1 supporting economical commercial flight operations. This research presents the data from a Taguchi array on low speed with twin wing designs to establish the design parameters for their use in low speed and high altitude. Also presented is how aerodynamic advantages can be achieved through understanding the interactions of parameters and their use. This is compared to operational effectiveness when applied to remotely piloted aircraft that are …

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 …