Mechanical Engineering Commons^™

Characterization Of Impact Properties Of Forged, Layered, And Additive Manufactured Titanium Alloy, Melissa Kathryn Matthes

UNLV Theses, Dissertations, Professional Papers, and Capstones

New additive manufactured (AM) materials have the potential of optimizing the geometry and microstructure of complex components to enhance their structural integrity while creating them quickly. However, the behavior of AM materials under extreme dynamic loading conditions is not fully understood. This is especially important in many applications. For example, spacecraft components may be impacted by micrometeorites at hyper velocities of multiple kilometers per second, inducing extreme dynamic loading.

One type of AM material is created by melting and solidifying metal along a specified path. Depending on the geometry, additional streams will be deposited side-by-side. This process affects the microstructure …

Investigation Of Digital Pump/Motor Control Strategies, Farid El Breidi

Open Access Dissertations

A pump is the heart of fluid power systems, it has a significant impact on the efficiency of many fluid power systems. Motors are the most common rotary actuators in fluid power systems. State-of-the-art pump/motor units can achieve efficiencies higher than 90% when operating at maximum displacement; however, as the displacement drops, the efficiency of these units drops to below 50%. A new digital pump/motor design aims at increasing these efficiencies by utilizing two electrically controlled high speed on/off valves per displacement chamber; these valves provide the ability to achieve variable displacement and allow freedom in choosing operating strategies. Such …

The Development Of A Prosthetic Training Software For Upper Limb Amputees, Tyler Kayne Sullins

USF Tampa Graduate Theses and Dissertations

The purpose of this study was to develop an intuitive software that aids in the field of prosthetic training and rehabilitation by creating an individualized visualization of joint angles. This software is titled “the prosthetic training software (PTS) for individualized joint angle representation”, and it enables the individualized portrayal of predicted or pre-recorded joint angles. The PTS is an intuitive program for clinicians and prosthesis users that produces an animation of a virtual avatar reflecting the user’s segment lengths and amputation for rehabilitation and training purposes.

The PTS consists of a graphical user interface (GUI) and a 3D visualization of …

Energy Models Of The Txaire Houses, Tajudeen Amadu Annafi

Mechanical Engineering Theses

Model calibration is important as its functions improve building models. A calibrated model of the TxAIRE Houses #1 and #2 have been developed using the OpenStudio software. The model was developed and calibrated with data of the year 2014 but can be used predict electricity consumption of any year.

An actual meteorological year (AMY) weather file was also created for the houses which was used for calibration. The data used to develop this weather file were measured on-site which improved the accuracy of the model. It was found that an error difference of -1.0 % and -4.2 % occurred between …

3d Infrastructure Condition Assessment For Rail Highway Applications, Teng Wang

Theses and Dissertations--Civil Engineering

Highway roughness is a concern for both the motoring public and highway authorities. Roughness may even increase the risk of crashes. Rail-highway grade crossings are particularly problematic. Roughness may be due to deterioration or simply due to the way the crossing was built to accommodate grade change, local utilities, or rail elevation. With over 216,000 crossings in the US, maintenance is a vast undertaking. While methods are available to quantify highway roughness, no method exists to quantitatively assess the condition of rail crossings. Conventional inspection relies on a labor-intensive process of qualitative judgment. A quantifiable, objective and extensible procedure for …

Torque Accuracy Improvement Via Explicit Torque Feedback Control For Internal Combustion Spark Ignition Engines, Anwar Alkeilani

Wayne State University Dissertations

At the present time, both control and estimation accuracies of engine torque are causes for under-achieving optimal drivability and performance in today’s production vehicles. The major focus in this area has been to enhance torque estimation and control accuracies using existing open-loop torque control and estimation structures. Such an approach does not guarantee optimum torque tracking accuracy and optimum estimation accuracy due to air flow and efficiencies estimations errors. Furthermore, current approach overlooks the fast torque path tracking which does not have any related feedback. Recently, explicit torque feedback control has been proposed in the literature using either estimated or …

Simulation Of Scalability For Autonomous Mobile Microgrids, Nathan Beyers

Dissertations, Master's Theses and Master's Reports

Microgrids are small-scale, decentralized systems for generation, storage, and management of electricity to provide power within a local area. By establishing these microgrids using autonomous robots, they can be made safer and more easily reconfigurable. This thesis presents a plan and outlines the infrastructure needed for scaling up previous experimental work on such systems. This work brings together a variety of tools in the form of both software and hardware to set the stage for how further development can be completed. An architecture for physical testing has been built to validate the full potential of navigation and making electrical connections …

Efficient Time-Dependent System Reliability Analysis, Zhifu Zhu

Doctoral Dissertations

"Engineering systems are usually subjected to time-variant loads and operate under time-dependent uncertainty; system performances are therefore time-dependent. Accurate and efficient estimate of system reliability is crucial for decision makings on system design, lifetime cost estimate, maintenance strategy, etc. Although significant progresses have been made in time-independent reliability analysis for components and systems, time-dependent system reliability methodologies are still limited. This dissertation is motivated by the need of accurate and effective reliability prediction for engineering systems under time-dependent uncertainty. Based on the classic First and Second Order Reliability Method (FORM and SORM), a system reliability method is developed for multidisciplinary …