Mechanical Engineering Commons^™

High Temperature Ltcc Based Sic Double-Sided Cooling Power Electronic Module, Hao Zhang

Graduate Theses and Dissertations

This objective of this dissertation research is to investigate a module packaging technology for high temperature double-sided cooling power electronic module application. A high-temperature wire-bondless low-temperature co-fired ceramic (LTCC) based double-sided cooling power electronic module was designed, simulated and fabricated. In this module, the conventional copper base plate is removed to reduce the thermal resistance between the device junctions to the heat sink and to improve the reliability of the module by eliminating the large area solder joint between the power substrate and the copper base plate. A low-temperature co-fired ceramic (LTCC) substrate with cavities and vias is used as …

Fundamentals Of Machine Design And Manufacturing: Design Of A Compliant Winding Machine, Gazal Kaur Nagi

Doctoral Dissertations and Master's Theses

A Sparton Electronics Compliant Winding Machine has been redesigned for improved performance. Thorough study of the existing machine identified issues such as the inconsistent diameter and pitch of the compliant wind, outdated equipment, as well as safety and ergonomic issues. A comprehensive methodology for the design of the new machine is presented through using CAD systems and advanced analysis tools, such as Finite Element Analysis, and HEEDS. Resulting, the machine is successfully re-designed to fully control the diameter and the pitch of the product via servo motors and a control panel. The safety and ergonomic issues are effectively resolved by …

Simulation Of Thermal Transit-Time Flow Meter For High Temperature, Corrosive And Irradiation Environment, Elaheh Alidoosti

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the environments of high temperature (300o C - 1000o C), corrosive and even irradiation application, the challenges of providing reliable and accurate flow rate measurement is significant. In comparing with many other existing technologies for normal operation environments, correlated thermal transit-time flow meter show its advantages of resolving the challenges encountered in those harsh conditions. The correlated thermal signals can be detected by two separated thermal sensors (for example, thermocouples) in series alignment along the pipe, and derive the flow rate. It was evaluated to have accurate measurement for small pipe at slow fluid speed. In the higher flow …

Study Of Water Transport Phenomena On Cathode Of Pemfcs Using Monte Carlo Simulation, Karn Soontrapa

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation deals with the development of a three-dimensional computational model of water transport phenomena in the cathode catalyst layer (CCL) of PEMFCs. The catalyst layer in the numerical simulation was developed using the optimized sphere packing algorithm. The optimization technique named the adaptive random search technique (ARSET) was employed in this packing algorithm. The ARSET algorithm will generate the initial location of spheres and allow them to move in the random direction with the variable moving distance, randomly selected from the sampling range, based on the Lennard-jones potential of the current and new configuration. The solid fraction values obtained …

Inkjet Printing Of Three-Dimensional Vascular-Like Constructs From Cell Suspensions, Changxue Xu

All Dissertations

Inkjet printing has found an increasing number of biofabrication applications, specifically organ printing, which has been emerging as a promising solution to the organ donor shortage. While some studies have been conducted to investigate various engineering problems associated with DOD inkjet printing of biological material-based fluids, the pinch-off, the cell-laden droplet formation, the effects of electric field on droplet formation, and challenges in 3D vascular-like construct fabrication haven't been systematically investigated. The objective of this study is to investigate the pinch-off, the cell-laden droplet formation, the effects of electric field on droplet formation, and manufacturing challenges during fabrication using DOD …

Adaptive And Robust Braking-Traction Control Systems, John Adcox

All Dissertations

The designs of commercial Anti-Lock Braking Systems often rely on assumptions of a torsionally rigid tire-wheel system and heavily rely on hub-mounted wheel speed sensors to manage tire-road slip conditions. However, advancements in high-bandwidth braking systems, in-wheel motors, variations in tire/wheel designs, and loss of inflation pressure, have produced scenarios where the tire's torsional dynamics could be easily excited by the braking system actuator. In these scenarios, the slip conditions for the tire-belt/ring will be dynamically different from what can be inferred from the wheel speed sensors. This dissertation investigates the interaction of tire torsional dynamics with ABS & traction …

System Identification Of A Small Low-Cost Unmanned Aerial Vehicle Using Flight Data From Low-Cost Sensors, Nathan V. Hoffer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Remote sensing has usually been done with satellites and manned aircraft. While they can be useful, satellites and manned aircraft have issues in how quickly you can get data, process it, and go back to get more data. Small low-cost unmanned aerial vehicles (UAVs) overcome these issues. To collect precise data a precise model of the UAV is needed to develop the autopilot, make sure the aircraft flies well, and does not break. One method of making a model is system identification (system ID). In this thesis system ID of a small low-cost fixed-wing T-tail UAV is done. The equations …

Spacecraft Guidance Techniques For Maximizing Mission Success, Shane B. Robinson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Traditional spacecraft guidance techniques have the objective of deterministically minimizing fuel consumption. These traditional approaches to guidance are developed independently of the navigation system, and without regard to stochastic effects. This work presents and demonstrates a new approach to guidance design. This new approach seeks to maximize the probability of mission success by minimizing the variance of trajectory dispersions subject to a fuel consumption constraint. The fuel consumption constraint is imposed by formulating the dynamics in terms of a steering command, and placing a constraint on the final time. Stochastic quadratic synthesis is then used to solve for the nominal …

Uncertainty Analysis Of Mechanical Properties From Miniature Tensile Testing Of High Strength Steels, Deepthi Rao Malpally

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This Miniature mechanical testing study is concerned with the use of miniature specimens to identify the mechanical properties of stainless steel Type 304, sensitized Type 304 and SA516 Grade 70 carbon steel as a viable replacement for the standard sized mechanical testing. The study aims at obtaining suitable specimen geometry and tensile testing procedure for miniature mechanical testing whose mechanical properties are comparable to that of conventional specimens of ASTM A370-10 of the same steel. All specimens are at and the gauge length cross section will be varied to obtain suitable geometry. The miniature tensile testing results are further validated …

Anisotropy Of The Reynolds Stress Tensor In The Wakes Of Counter-Rotating Wind Turbine Arrays, Nicholas Michael Hamilton

Dissertations and Theses

A wind turbine array was constructed in the wind tunnel at Portland State University in a standard Cartesian arrangement. Configurations of the turbine array were tested with rotor blades set to rotate in either a clockwise or counter-clockwise sense. Measurements of velocity were made with stereo particle-image velocimetry. Mean statistics of velocities and Reynolds stresses clearly show the effect of direction of rotation of rotor blades for both entrance and exit row turbines. Rotational sense of the turbine blades is visible in the mean spanwise velocity W and the Reynolds shear stress -[macron over vw]. The normalized anisotropy tensor was …

Bifurcation Type Change Of Ac Electrostatically Actuated Mems Resonators Due To Dc Bias, Dumitru Caruntu, Kyle N. Taylor

Mechanical Engineering Faculty Publications

This paper investigates the nonlinear response of microelectromechanical system (MEMS) cantilever resonator electrostatically actuated by applying a soft alternating current (AC) voltage and an even softer direct current (DC) voltage between the resonators and a parallel fixed ground plate. The AC frequency is near natural frequency. This drives the resonator into nonlinear parametric resonance. The method ofmultiple scales (MMS) is used to solve the dimensionless differential equation of motion of the resonator and find the steady-state solutions.The reduced order model (ROM) method is used to validate the results obtained using MMS. The effect of the soft DC voltage (bias) component …

A Sinteractive Ni-Bazr0.8Y0.2O3-Δ Composite Membrane For Hydrogen Separation, Shumin Fang, Siwei Wang, Kyle S. Brinkman, Fanglin Chen

Faculty Publications

BaZr_0.8Y_0.2O_3−δ (BZY) is an excellent candidate material for hydrogen permeation membranes due to its high bulk proton conductivity, mechanical robustness, and chemical stability in H₂O- and CO₂-containing environments. Unfortunately, the use of BZY as a separation membrane has been greatly restrained by its highly refractory nature, poor grain boundary proton conductivity, high number of grain boundaries resulting from limited grain growth during sintering, as well as low electronic conductivity. These problems can be resolved by the fabrication of a Ni–BZY composite membrane with large BZY grains, which requires the development …

Application Of Limited Mixing In The Hele–Shaw Geometry In Fabrication Of Janus Hydrogels, Md Mahmudur Rahman

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

It is widely accepted that cells behave differently responding to the stiffness of their extracellular matrix (ECM). Such observations were made by culturing cells on hydrogel substrates of tunable stiffness. However, it was recently proposed that cells may sense how strongly they are tethered to ECM, not the local stiffness of ECM. To investigate both hypotheses, we developed a method to fabricate Janus polyacrylamide (PAAM) gels. We squeeze two drops of different concentrations in the Hele-Shaw geometry to generate radial Stokes flow. When the drops coalesce, limited mixing occurs at the interface due to the narrow confinement, and diffusion normal …

Mechanical Engineering News, Georgia Southern University

Mechanical Engineering: News & Publications (2013-2023)

• Dr. Mitra of Mechanical Engineering Receives National Recognition

Flow-Controlling Header, David J. Bayless, Morgan Lefay Vis-Chiasson, Gregory G. Kremer, Ben J. Stuart

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An apparatus and method for holding a membrane, screen or other flexible planar body in tension, while providing a conduit for water or other liquid to flow to the membrane being held. The membrane extends from inside a manifold body that carries the liquid, and the manifold body supports the membrane at one edge while the membrane is pulled in tension. Liquid pressure builds up inside the manifold body, preferably by entering a pressure chamber at the top of the manifold body. At a feeding pressure in the pressure chamber the liquid is distributed to the membrane for microbe growth. …

Semi-Annual Program Progress Performance Report For University Transportation Systems, Florida Solar Energy Center, David L. Block

FSEC Energy Research Center®

The Electric Vehicle Transportation Center's (EVTC) vision is to transform the country's transportation network into a fully integrated "smart" electric vehicle deployment system coupled with a "smart" electric grid achieved with maximum efficiency and minimum time and disruption.

To accomplish the EVTC vision, the Center's goals are to serve as the focal point for the U.S. Department of Transportation's strategic goal of planning for near-term integration of alternative fuel vehicles as a means to build a sustainable transportation system. The project will evaluate technologies, standards and policies to ensure seamless integration of EVs into a complex electricity grid and transportation …

Paint Book System Development, Dale Boynton

Undergraduate Research Symposium

Jarraff Industries has a current Paint Book System which is out of date. The current system is simply pictures of the parts and part numbers for them. It has old versions of parts in it. This creates confusion when the current parts show up and look different. Also, new pictures have to be taken every time a new part is made, which creates a delay in the process to update the books. For a solution three different samples for new Paint Books were made to distribute to users and get feedback on what they liked and did not like about …

3d Printing Of Stainless Steel For Engineering Applications, Michael Doyle

Undergraduate Research Symposium

3-D metal printing has the potential to solve problems in the medical, prototyping, automotive, aerospace, defense, and other engineering industries. To reach the potential of any manufacturing process, the final product’s material characteristics and how the process affects those characteristics must be understood to meet the demands of industrial applications. There is a gap in standard testing information regarding metal based 3-D metal printing processes. The purpose of this research is to fill that gap of valuable information for this manufacturing process, so that its principles can be used to design better products. Fundamental tensile and compression tests were executed …

Small Scale Wind Turbine, Cameron Allen, Davis Gumbo, Mitchell Petronek, Scott Roskens

College of Engineering Presentations

The Department of Energy (DOE) has put together a collegiate wind competition to design, build, and market a small wind turbine (17.7in diameter rotor dimension). For our mechanical engineering senior design project our team will participate in this competition. Ten schools will compete in the competition in Las Vegas this May. Our team designed a wind turbine to produce power for ultraviolet light water purification in remote areas and during emergency situations. The turbine was designed to produce 10 watts at a wind speed between 5 and 14 m/s. The turbine is also equipped with an emergency brake that will …

Stability Of N=6 Normal And Right-Angled Kaleidocycles Under The Influence Of Energy Elements, Brett Rowberry, Dr. Larry Howell

Journal of Undergraduate Research

Normal and right-angled n=6 kaleidocycles are structures composed of six tetrahedra. They are capable of continuous rotation while only requiring 240° of rotation on each joint between adjacent tetrahedra. Because of this fact, kaleidocycles may be made fully compliant with no moving parts. Having continuous rotation in a monolithic fully compliant structure is rare, if not unique. One consequence of having compliant joints is that as they are flexed from their unstrained positions, energy is stored. As the kaleidocycle is rotated, energy is stored and released from each of the joints in a complex manner. The purpose of this research …