Mechanical Engineering Commons^™

Network Target Coordination For Design Optimization Of Decomposed Systems, Wenshan Wang

All Dissertations

A complex engineered system is often decomposed into a number of different subsystems that interact on one another and together produce results not obtainable by the subsystems alone. Effective coordination of the interdependencies shared among these subsystems is critical to fulfill the stakeholder expectations and technical requirements of the original system. The past research has shown that various coordination methods obtain different solution accuracies and exhibit different computational efficiencies when solving a decomposed system. Addressing these coordination decisions may lead to improved complex system design. This dissertation studies coordination methods through two types of decomposition structures, hierarchical, and nonhierarchical.
For …

Computational Fluid Dynamics Investigation Of The Orientation Of A Pediatric Left Ventricle Assist Device Cannula To Reduce Stroke Events, Stephen Guimond

HIM 1990-2015

Ventricle Assist Devices (VADs), which are typically either axial or centrifugal flow pumps implanted on the aortic arch, have been used to support patients who are awaiting cardiac transplantation. Success of the apparatus in the short term has led to long term use. Despite anticoagulation measures, blood clots (thrombi) have been known to form in the device itself or inside of the heart. The Ventricle Assist Devices supply blood flow via a conduit (cannula) implanted on the ascending aorta. Currently, the implantation angle of the VAD cannula is not taken into consideration. Since the VADs supply a significant amount of …

Plasma Test On Industrial Diamond Powder In Hydrogen And Air For Fracture Strength Study, Rohit Asuri Sudharshana Asuri Sudharshana Chary

UNLV Theses, Dissertations, Professional Papers, and Capstones

Diamonds are the most precious material all over the world. Ever since their discovery, the desire for natural diamonds has been great; recently, the demand has steeply increased, leading to scarcity. For example, in 2010, diamonds worth $50 billion were marketed. This increased demand has led to discovering alternative sources to replace diamonds. The diamond, being the hardest material on earth, could be replaced with no other material except another diamond. Thus, the industrial or synthetic diamond was invented. Because of extreme hardness is one of diamond's properties, diamonds are used in cutting operations. The fracture strength of diamond is …

Me-Em Enewsbrief, December 2012, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

Testing, Analysis, And Model Verification Of Miniature Linear Permanent Magnet Generators, Michael Ray Rippee

Boise State University Theses and Dissertations

The military has become increasingly dependent on mobile electronic equipment to ensure success and safety of soldiers in remote locations. To operate the electronics, soldiers must carry batteries that can weigh up to 12kg (26.5lb). To decrease the load soldiers must carry, a backpack with an internal linear electric generator has been proposed to provide portable power for soldiers on foot. In designing a generator for this purpose, a simulation was developed to predict the power generation capacity of linear permanent magnet generators. This thesis presents work done to experimentally verify the theoretical simulation with a desired accuracy of 20%. …

Defect Detection In Railroad Tapered-Roller Bearings Using Vibration Analysis Techniques, Iris L. Alvarado

Theses and Dissertations - UTB/UTPA

Derailments can often lead to great damage, loss of lives, and massive costs associated with the railroad infrastructure. A significant cause of derailments is premature bearing failure, and therefore bearing condition-monitoring systems that can detect developing defects are of great importance. Based on an investigation conducted at the University of Texas-Pan American on the development of a vibration and temperature monitoring system, an algorithm is devised utilizing various vibration analysis techniques. The proposed algorithm determines whether a bearing is defective, the type of defect present, the defective component (i.e. cup, cone, or roller), and the size of the defect. Speed-dependent …

Improving The Mechanical Properties Of Polymers By Adding Self-Healing Capabilities, Alma Perez

Theses and Dissertations - UTB/UTPA

The addition of self-healing capabilities to polymers through the dispersion of First Generation Grubbs’ Catalyst (FGGC) and poly(urea-formaldehyde) (PUF) microcapsules filled with dicyclopentadiene (DCPD) as the healing agent, has been investigated by various experimental techniques such as Optical microscopy, Scanning Electron Microscopy, Tensile tests, Raman Spectroscopy, and Themogravimmetric Analysis (TGA). Optical and Scanning Electron Microscopy revealed the morphology of the surface of the PUF microcapsules, the diameter size distribution and the thickness of the shell, and their structure when dispersed in the polymeric matrices. Photos taken after the tensile test showed broken microcapsules on both polymer matrices having released the …

Design And Simulation Of Passive Thermal Management System For Lithium-Ion Battery Packs On An Unmanned Ground Vehicle, Kevin Kenneth Parsons

Master's Theses

The transient thermal response of a 15-cell, 48 volt, lithium-ion battery pack for an unmanned ground vehicle was simulated with ANSYS Fluent. Heat generation rates and specific heat capacity of a single cell were experimentally measured and used as input to the thermal model. A heat generation load was applied to each battery and natural convection film boundary conditions were applied to the exterior of the enclosure. The buoyancy-driven natural convection inside the enclosure was modeled along with the radiation heat transfer between internal components. The maximum temperature of the batteries reached 65.6 °C after 630 seconds of usage …

Investigation Of The Noise Floor Of The Standard Piv Cross-Correlation Algorithm, Kyle L. Jones

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Particle image velocimetry (PIV) is a powerful measurement technique used to acquire instantaneous measurements of entire flow fields at a given instant in time. Quantifying the uncertainty and error in PIV is a critical part of realizing the full potential of PIV as a flow measurement technique.

The noise floor of PIV is the minimum amount of random error that can be achieved for a particular standard cross-correlation (SCC) algorithm. The noise floor of the SCC used by DaVis in correlating image pairs is explored. Two methods for creating image pairs for correlation are compared, namely pseudo image pairs and …

Novel Airframe Design For The Dual-Aircraft Atmospheric Platform Flight Concept, Eric Michael Mckee

Doctoral Dissertations and Master's Theses

A high-altitude, long-endurance unmanned aerial airframe was designed for the innovative Dual-Aircraft Atmospheric Platform flight concept that exploits stratospheric wind velocity gradients to remain aloft indefinitely. Classical aircraft preliminary design techniques and high-fidelity tools were used to establish a baseline configuration.

Performance characteristics of numerous airfoil profiles were evaluated with two-dimensional flow software in an effort to determine the best-candidate airfoil for the unique application. Vortex-Lattice method tools were used to investigate the sensitivity of three-dimensional design parameters upon overall vehicle aerodynamic performance and determine both static and dynamic stability characteristics of the airframe. Performance capabilities of the finalized airframe …

Investigation Of Shroud Geometry To Passively Improve Heat Transfer In A Solar Thermal Storage Tank, Matthew Keene Zemler

Doctoral Dissertations and Master's Theses

A shroud and baffle configuration is used to passively increase heat transfer in a thermal store. The shroud and baffle are used to create a vena contracta near the surface of the heat exchanger, which will speed up the flow locally and thereby increasing heat transfer. The goal of this study is to investigate the geometry of the shroud in optimizing heat transfer by locally increasing the velocity near the surface of the heat exchanger. Two-dimensional transient simulations are conducted. The immersed heat exchanger is modeled as an isothermal cylinder, which is situated at the top of a solar thermal …

Development Of A Vibration And Temperature Measurement Device For Railroad Bearings, Andrea P. Arguelles

Theses and Dissertations - UTB/UTPA

Bearing related derailments cause very high cost and inconvenience to the railroad industry. Various wayside detection systems have been implemented to assess bearing condition and prevent premature failure. However, current devices fail to determine the internal condition of bearings or provide insight regarding the danger and severity of defects and abnormalities that may be present. To this end, a device combining both temperature and vibration detection was designed to be embedded in railroad bearing adapters. In order to efficiently design a railroad bearing condition-monitoring system, two factors that must be considered are the capabilities available to operate the different sensors …

Development Of Algorithms And Criteria For Continuous Condition Monitoring Of Railroad Bearings, Sean Michael Woods

Theses and Dissertations - UTB/UTPA

This thesis summarizes research conducted at the University of Texas-Pan American to investigate the implementation of condition monitoring algorithms for use with railway roller bearings equipped with wireless temperature sensor nodes. Current temperature based condition monitoring techniques utilize wayside detection equipment intermittently located along the track to garner sporadic bearing cup temperatures. Such devices are not capable of detecting brief transient temperature trending events. The developed algorithms were tested using a fleet of ten railway freight cars instrumented with wireless sensor nodes and operated by an Australian freight transportation company. Eighteen months of continuous monitoring combined with the inspection of …

Control Charts For First Order Autoregressive Analysis With An Exogenous Variable, Becky M. Vela

Theses and Dissertations - UTB/UTPA

There are many instances in industry, where the necessity of prediction models is extremely important. However, the difficulty of forecasting increases with the number of variables involved, and determining independent variables from dependent variables. Autocorrelation is one of the most common causes for many control charts and other quality measurement tools to falsely signal an error in the process. Time series models, such as autoregressive models, accommodate autocorrelated data to a certain extent. However, using a model that only analyzes historical data alone does not possess the accuracy necessary to be able to forecast data precisely. An addition of an …

Fabrication And Characterization Of Polylactic Acid And Polylactic Acid/Multi-Walled Carbon Nanotube Nanofibers Through Centrifugal Spinning, Richard Patlan

Theses and Dissertations - UTB/UTPA

Biocompatible polymer nanofibers hold great potential in the biomedical engineering field. Their biodegradable nature and enhanced properties could help solve a wide array of health related problems, particularly in the areas of tissue regeneration, drug delivery, and biosensor design. The novel ForcespinningTM method allows the production of submicron fibers without many of the drawbacks found in electrospinning, while also providing a substantial increase in fiber production. The aim of the study was to utilize this method to fabricate non-woven nanofibrous mats composed of polylactic acid (PLA) and polylactic acid/multi-walled carbon nanotube composite fibers. The morphology, thermal properties, and crystalline structure …

Loss Enhanced Transmission And Collimation In Anisotropic Epsilon-Near-Zero Metamaterials, L. Sun, S. Feng, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We verify the extraordinary transmission enhancement and collimation induced by the material loss in anisotropic epsilon-near-zero metamaterials, and reveal the physical mechanism of this exotic electromagnetic phenomenon via the iso-frequency contour analysis. In addition, we demonstrate the possibility in realization of such loss enhanced transmission of Gaussian beam in realistic silver-germanium multilayered structures by applying full-wave numerical simulations.

Experimental Determination Of Colburn And Friction Factors In Small Plate Heat Exchangers With High Surface Enlargement Factors, Andrew H. Pike

Masters Theses

Experiments were conducted to measure the performance of several small brazed plate heat exchangers. A test apparatus was designed and constructed that allowed for the easy switching of the plate heat exchangers, as well as having the ability to electronically monitor and record the inlet and outlet temperatures, pressures, and flow rates. The flow rates and applied electrical power were controlled electronically by the same program which recorded the data. De-ionized water was used as the heat transfer medium to reduce the uncertainty related to fluid properties.

An existing mathematical model was used to create Colburn and friction factors based …

High Capacity Lithium-Ion Battery Characterization For Vehicular Applications, Sazzad Hossain Ahmed

Masters Theses

A lithium-ion battery is one of the key research topics in energy storage technologies. Major characterization tests such as static capacity, open circuit voltage (OCV), hybrid pulse power characterization (HPPC) have been conducted on two different chemistries, LiMnNi and LiFePO₄, high capacity lithium-ion batteries over a wide range of temperatures from 50ºC to -30ºC. Detail analysis of temperature effects on battery capacity and simple models of direct current resistance (DCR) increment and power decrement over temperatures have been proposed using the test results. Electrochemical impedance spectroscopy (EIS) tests have been performed to find out the dominant internal resistances …

Computational Design Of The Electrical And Mechanical Performance Of Steerable Mems Antennas, Morgan Andrew Roddy

Graduate Theses and Dissertations

This thesis describes the origins, improvements, and variations of a broadband microwave antenna that can be beam-steered by a micro-electromechanical system (MEMS). The steerable MEMS antenna of this work was comprised of a planar antenna on top of a Silicon membrane. The membrane is etched to create a gimbal hinge structure and a platform which supported the antenna and gave it one or two degrees of freedom of rotation. The antennas presented were broadband and fed by a coplanar waveguide (CPW) transmission line which traversed the hinge structure. The antenna's orientation in space was designed to be changed through electrostatic …

Potential Energy Cost Savings By Use Of Building Roofs As Thermal Storage Of A Multi-Storied Building, Ahmad Adam Shelbaya

Masters Theses and Doctoral Dissertations

The thermal mass of a building has been used for more than two decades to shift the peak cooling load occurring during the day time to evening or night time. This is typically accomplished by use of concrete slabs embedded with pipes carrying hot or chilled water to meet the heating or cooling load, respectively. The water temperature drops across the coils and the frequency and intensity of room air circulation can be varied, along with controlling the gains through the windows, to shift the peak load hours to the nighttime when energy costs are cheaper and electric demands are …