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Full-Text Articles in Mechanical Engineering

Variable Fluid Flow Regimes Alter Endothelial Adherens Junctions And Tight Junctions, Dilshan Ranadewa May 2019

Variable Fluid Flow Regimes Alter Endothelial Adherens Junctions And Tight Junctions, Dilshan Ranadewa

Electronic Theses and Dissertations

Variable blood flow regimes influence a range of cellular properties ranging from cell orientation, shape, and permeability: all of which are dependent on endothelial cell-cell junctions. In fact, cell-cell junctions have shown to be an integral part of vascular homeostasis through the endothelium by allowing intercellular signaling and passage control through tight junctions (TJs), adherens junctions (AJs), and gap junctions (GJs). It was our objective to determine the structural response of both AJs and TJs under steady and oscillatory flow. Human brain microvascular endothelial cells (HBMECs) were cultured in a parallel plate flow chamber and exposed to separate trails of ...


Vibration Reduction Of Mistuned Bladed Disks Via Piezoelectric-Based Resonance Frequency Detuning, Garrett Lopp May 2019

Vibration Reduction Of Mistuned Bladed Disks Via Piezoelectric-Based Resonance Frequency Detuning, Garrett Lopp

Electronic Theses and Dissertations

Recent trends in turbomachinery blade technology have led to increased use of monolithically constructed bladed disks (blisks). Although offering a wealth of performance benefits, this construction removes the blade-attachment interface present in the conventional design, thus unintentionally removing a source of friction-based damping needed to counteract large vibrations during resonance passages. This issue is further exacerbated in the presence of blade mistuning that arises from small imperfections from otherwise identical blades and are unavoidable as they originate from manufacturing tolerances and operational wear over the lifespan of the engine. Mistuning is known to induce vibration localization with large vibration amplitudes ...


Dynamic Behavior And Performance Of Different Types Of Multi-Effect Desalination Plants, Mohamed Abdelkareem May 2019

Dynamic Behavior And Performance Of Different Types Of Multi-Effect Desalination Plants, Mohamed Abdelkareem

Electronic Theses and Dissertations

Water and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of primary energy and electricity consumption compared to other thermal desalination systems. The motivation for this research is to address thermo-economics and dynamic behavior ...


Mechanical Properties Of Brittle Ceramics: Case Study Of Boron Rich Ceramics And Acropora Cervicornis Coral Skeleton, Alejandro Carrasco-Pena May 2019

Mechanical Properties Of Brittle Ceramics: Case Study Of Boron Rich Ceramics And Acropora Cervicornis Coral Skeleton, Alejandro Carrasco-Pena

Electronic Theses and Dissertations

Ceramics are ubiquitous in man-made and natural structures. Their mechanical properties highly depend on their composition, microstructure and level of defects in the bulk of the material, the latter affecting the integrity of the components; such is the case of boron-rich ceramics where large agglomerates create high stressed regions, or coral skeleton where porosity determines their strength against hydrodynamic forces present in the ocean tides. Therefore, studying the properties of ceramic materials using invasive and non-invasive methods helps in the understanding of the link between the properties and the performance of the structures. The aim of this research was to ...


Modeling And Transient Simulation Of A Fully Integrated Multi-Pressure Heat Recovery Steam Generator Using Siemens T3000, Jonathan Mcconnell Jan 2019

Modeling And Transient Simulation Of A Fully Integrated Multi-Pressure Heat Recovery Steam Generator Using Siemens T3000, Jonathan Mcconnell

Electronic Theses and Dissertations

The focus of this research is on the transient thermodynamic properties and dynamic behavior of a Heat Recovery Steam Generator (HRSG). An HRSG is a crossflow heat exchanger designed for the extraction of energy from the hot exhaust gas of a traditional power plant through boiling induced phase change. Superheated steam is sent through a turbine to generate additional power, raising the overall efficiency of a power plant. The addition of renewable energies and the evolution of smart grids have brought forth a necessity to gain a comprehensive understanding of transient behavior within an HRSG in order to efficiently manage ...


Fluid Flow Characteristics Of A Co-Flow Fluidic Slot Jet Thrust Augmentation Propulsion System, Brian Garrett Jan 2019

Fluid Flow Characteristics Of A Co-Flow Fluidic Slot Jet Thrust Augmentation Propulsion System, Brian Garrett

Electronic Theses and Dissertations

The UAV industry is booming with investments in research and development on improving UAV systems in order to increase applications and reduce costs of the use of these machines. Current UAV machines are developed according to the quadcopter design which has a rotary propulsion system which provides the lift needed for the aerial vehicles. This design has some flaws; namely safety concerns and noise/vibration production both of which come from the rotary propulsion system. As such, a novel propulsion system using slip stream air passed through high performance slot jets is proposed and analysis of the fluid characteristics is ...


Experimental And Numerical Investigation Of A Novel Adsorption Bed Design For Cooling Applications, Ramy H. Mohammed Jan 2019

Experimental And Numerical Investigation Of A Novel Adsorption Bed Design For Cooling Applications, Ramy H. Mohammed

Electronic Theses and Dissertations

A global challenge is to develop environmentally friendly, affordable, compact and sustainable technologies to provide heating and cooling power. Adsorption cooling (AC) technology is one of the most promising ways to solve the environmental issues and cut down the energy consumption related to the traditional air conditioning and refrigeration systems. However, AC systems still suffer from poor heat and mass transfer inside the adsorption bed, which is the main obstacle to commercialization of adsorption cooling units. The main goal of this study is designing an efficient adsorption cooling cycle. In this research work, an in-depth scaling analysis of heat and ...


Cavitation And Heat Transfer Over Micro Pin Fins, Arash Nayebzadeh Jan 2019

Cavitation And Heat Transfer Over Micro Pin Fins, Arash Nayebzadeh

Electronic Theses and Dissertations

With the dramatic increase in the usage of compact yet more powerful electronic devices, advanced cooling technologies are required to maintain delicate electronic components below their maximum allowable temperatures and prevent them from failure. One solution is to use innovative pin finned heat sinks. This research is centered on the evaluation of hydrodynamic cavitation properties downstream pin fins and extended toward single-phase heat transfer enhancement of array of pin fins in microchannel. In this work, transparent micro-devices capable of local wall temperature measurements were micro fabricated and tested. Various experimental methods, numerical modeling and advanced data processing techniques are presented ...


Shape Recovery Behavior Of Carbon Nanopaper Shape Memory Polymer Composite, Veli Bugra Ozdemir Jan 2019

Shape Recovery Behavior Of Carbon Nanopaper Shape Memory Polymer Composite, Veli Bugra Ozdemir

Electronic Theses and Dissertations

This thesis presents analytical, experimental and modeling studies of the shape recovery behavior of electrically activated Carbon Nanopaper (CNP) Shape Memory Polymer (SMP)composite. The composite structure studied consists of a CNP layer sandwiched by two SMP layers where the CNP layer acts as a flexible electrical heater when a voltage difference is applied. The behavior of CNP/SMP composite presents a coupled electrical - thermal - structural problem. The governing equations for the multiphysics behavior are derived. Derived parameters as a result of multiphysics analysis and effects of these parameters on the shape recovery behavior are investigated. The mechanical properties of ...


Investigation Of Flow Field Structures In A Rectangular Channel With A Pin Fin Array, Patrick Tran Jan 2019

Investigation Of Flow Field Structures In A Rectangular Channel With A Pin Fin Array, Patrick Tran

Electronic Theses and Dissertations

Pin fin arrays are commonly found in heat exchangers, turbine blades, and electronic heat sinks. Fin arrays are extended surfaces that are used as turbulence promoters by inducing horseshoe vortex (HSV) and von Karman vortex (KV) structures. The horseshoe vortex are primarily studied in the leading edge of the blunt body, whereas the KV are formed in the trailing side. This study presents an experimental investigation of flow field structures and pressure loss on staggered pin fin array in the wake region, where KV are dominate. These flow structures increase the local levels turbulence and generate eddies that promote flow ...


Mechanical Characterization Of Anisotropic Fused Deposition Modeled Polylactic Acid Under Combined Monotonic Bending And Torsion Conditions, Aaron T. Santomauro Jan 2019

Mechanical Characterization Of Anisotropic Fused Deposition Modeled Polylactic Acid Under Combined Monotonic Bending And Torsion Conditions, Aaron T. Santomauro

Honors Undergraduate Theses

Mechanical strength of polylactic acid (PLA) is increasingly relevant with time because of its attractive mechanical properties and 3D printability. Additive manufacturing (AM) methods, such as fused deposition modeling (FDM), stereolithography (SLA), and selective laser sintering (SLS), serve a vital role in assisting designers with cheap and efficient generation of the desired components. This document presents research to investigate the anisotropic response of multi-oriented PLA subjected to multiple monotonic loading conditions. Although empirical data has previously been captured for multi-oriented PLA under tensile and compressive loading conditions, the data has yet to be applied with regard to a representative component ...


The Subject Librarian Newsletter, Engineering And Computer Science, Spring 2018, Buenaventura "Ven" Basco Mar 2018

The Subject Librarian Newsletter, Engineering And Computer Science, Spring 2018, Buenaventura "Ven" Basco

Libraries' Newsletters

No abstract provided.


Experimental Investigation Of Advanced Ignition Systems For High Efficiency Combustion, Bader Almansour Jan 2018

Experimental Investigation Of Advanced Ignition Systems For High Efficiency Combustion, Bader Almansour

Electronic Theses and Dissertations

Consumption of fossil and bio-derived fuels is growing due to energy demands associated with increase in population and standard of living across the globe. Power generation and transportation sectors are the primary two sources of fuel consumption, which have raised the demand for crude oil and led to serious environmental pollution issues. This demand for energy forced various government agencies to strengthen the allowable exhaust pollutant concentration limits. Recently, CO, CO2, particulate matter, and nitrogen oxides (NOx) emission restrictions have become more stringent to the extent that engines must operate at higher energy densities and efficiencies. Towards this goal, this ...


Investigation Into The Feasibility Of Adding Turbulators To Rocket Combustion Chamber Cooling Channels Using A Conjugate Heat Transfer Analysis, Tyler Buchanan Jan 2018

Investigation Into The Feasibility Of Adding Turbulators To Rocket Combustion Chamber Cooling Channels Using A Conjugate Heat Transfer Analysis, Tyler Buchanan

Electronic Theses and Dissertations

A conjugate heat transfer analysis will be carried out to simulate an 89 kN thrust chamber hydrogen cooling channel, to determine the feasibility of adding turbulators to the combustion chamber cooling channels at various parameters such as angle, pitch, and height of the turbulator. An existing regeneratively cooled chamber environment is simulated and used as a baseline case to be compared against. The new design includes using ribbed turbulators or delta wedges in the cooling channels to increase the heat transfer on the channel hot wall (wall adjacent to the hot gas wall) and on the two channel sidewalls. With ...


Flutter Stability Of Shrouded Turbomachinery Cascades With Nonlinear Frictional Damping, Alex Torkaman Jan 2018

Flutter Stability Of Shrouded Turbomachinery Cascades With Nonlinear Frictional Damping, Alex Torkaman

Electronic Theses and Dissertations

Prediction of flutter in shrouded turbomachinery cascades is difficult due to i) coupling of aerodynamic drivers and structural dynamics of the cascade through shrouds, and ii) presence of nonlinear dry friction damping as a result of relative motion between adjacent shrouds. An analytical framework is developed in this dissertation to determine flutter stability of shrouded cascades with consideration of friction damping. This framework is an extension to the well-established energy method, and it includes all contributing factors affecting stability of the cascade such as aerodynamic excitation and the stabilizing effects of dry friction damping caused by nonlinear contact forces between ...


Mechanism Design Of A Compact 4-Dof Robotic Needle Guide For Mri-Guided Prostate Intervention, Shihao Zhang Jan 2018

Mechanism Design Of A Compact 4-Dof Robotic Needle Guide For Mri-Guided Prostate Intervention, Shihao Zhang

Electronic Theses and Dissertations

In the past several MRI compatible robotic needle guide devices for targeted prostate biopsy have been developed. The large and complex structure have been identified as the major limitations of those devices. Such limitations, in addition to complex steps for device to image registration have prevented widespread implementation of MRI-guided prostate biopsy despite the advantages of MRI compared to TRUS. We have designed a compact MRI-guided robotic intervention with the capability to have angulated insertion to avoid damage to any anatomical feature along the needle path. The system consists of a novel mechanism driven Robotic Needle Guide (RNG). The RNG ...


A Modeling Framework Of Brittle And Ductile Fractures Coexistence In Composites, Yangyang Qiao Jan 2018

A Modeling Framework Of Brittle And Ductile Fractures Coexistence In Composites, Yangyang Qiao

Electronic Theses and Dissertations

In order to reduce the weight of automobiles and aircrafts, lightweight materials, such as aluminum alloy, advanced high strength steel, composite materials, are widely used to replace the traditional materials like mild steel. Composite materials are complicated in material mechanical properties and less investigated compared to metallic materials. Engineering composites can be categorized into polymer matrix composites (PMCs), metal matrix composites (MMCs) and ceramic matrix composites (CMCs) according to their matrix materials. A set of mechanical experiments ranging from micro scale (single fiber composite and thin film composite) to macro scale (PMCs and MMCs) were conducted to fully understand the ...


Characterization, Classification, And Genesis Of Seismocardiographic Signals, Amirtaha Taebi Jan 2018

Characterization, Classification, And Genesis Of Seismocardiographic Signals, Amirtaha Taebi

Electronic Theses and Dissertations

Seismocardiographic (SCG) signals are the acoustic and vibration induced by cardiac activity measured non-invasively at the chest surface. These signals may offer a method for diagnosing and monitoring heart function. Successful classification of SCG signals in health and disease depends on accurate signal characterization and feature extraction. In this study, SCG signal features were extracted in the time, frequency, and time-frequency domains. Different methods for estimating time-frequency features of SCG were investigated. Results suggested that the polynomial chirplet transform outperformed wavelet and short time Fourier transforms. Many factors may contribute to increasing intrasubject SCG variability including subject posture and respiratory ...


A Framework For Miniaturized Mechanical Characterization Of Tensile, Creep, And Fatigue Properties Of Slm Alloys, Jonathan Torres-Caceres Jan 2018

A Framework For Miniaturized Mechanical Characterization Of Tensile, Creep, And Fatigue Properties Of Slm Alloys, Jonathan Torres-Caceres

Electronic Theses and Dissertations

With the heightened design complexity that may be achieved through additive manufacturing (AM) comes an equally complex set of distinct material characteristics. To properly characterize new materials for use in selective laser melting (SLM), extensive analysis is necessary. Traditional testing techniques, however, can be prohibitive in time and cost incurred. The small punch test (SPT) has been developed for such purposes, where material is scarce or costly. Although lacking standardization, SPT has been successfully employed with various materials to assess material properties such as the yield and ultimate strength and verified by traditional testing results. With the accompaniment of numerical ...


Mimicking Blood Rheology For More Accurate Modeling In Benchtop Research, Lindsey Webb Jan 2018

Mimicking Blood Rheology For More Accurate Modeling In Benchtop Research, Lindsey Webb

Honors Undergraduate Theses

To confirm computer simulations and Computational Fluid Dynamics (CFD) analysis, benchtop experiments are needed with a fluid that mimics blood and its viscoelastic properties. Blood is challenging to use as a working fluid in a laboratory setting because of health and safety concerns. Therefore, a blood analogue is necessary to perform benchtop experiments. Viscosity is an important property of fluids for modeling and experiments. Blood is a shear thinning fluid, so it has a decreasing viscosity with higher shear rates. This project seeks to create a blood mimicking fluid for benchtop laboratory use. Numerous fluids with different combinations of water ...


Biomechanical Models Of Human Upper And Tracheal Airway Functionality, Don Nadun Kuruppumullage Jan 2018

Biomechanical Models Of Human Upper And Tracheal Airway Functionality, Don Nadun Kuruppumullage

Electronic Theses and Dissertations

The respiratory tract, in other words, the airway, is the primary airflow path for several physiological activities such as coughing, breathing, and sneezing. Diseases can impact airway functionality through various means including cancer of the head and neck, Neurological disorders such as Parkinson's disease, and sleep disorders and all of which are considered in this study. In this dissertation, numerical modeling techniques were used to simulate three distinct airway diseases: a weak cough leading to aspiration, upper airway patency in obstructive sleep apnea, and tongue cancer in swallow disorders. The work described in this dissertation, therefore, divided into three ...


Characterization Of Anisotropic Mechanical Performance Of As-Built Additively Manufactured Metals, Sanna Siddiqui Jan 2018

Characterization Of Anisotropic Mechanical Performance Of As-Built Additively Manufactured Metals, Sanna Siddiqui

Electronic Theses and Dissertations

Additive manufacturing (AM) technologies use a 3D Computer Aided Design (CAD) model to develop a component through a deposition and fusion layer process, allowing for rapid design and geometric flexibility of metal components, for use in the aerospace, energy and biomedical industries. Challenges exist with additive manufacturing that limits its replacement of conventional manufacturing techniques, most especially a comprehensive understanding of the anisotropic behavior of these materials and how it is reflected in observed tensile, torsional and fatigue mechanical responses. As such, there is a need to understand how the build orientation of as-built additively manufactured metals, affects mechanical performance ...


Application Of Trained Pod-Rbf To Interpolation In Heat Transfer And Fluid Mechanics, Rebecca A. Ashley Jan 2018

Application Of Trained Pod-Rbf To Interpolation In Heat Transfer And Fluid Mechanics, Rebecca A. Ashley

Honors Undergraduate Theses

To accurately model or predict future operating conditions of a system in engineering or applied mechanics, it is necessary to understand its fundamental principles. These may be the material parameters, defining dimensional characteristics, or the boundary conditions. However, there are instances when there is little to no prior knowledge of the system properties or conditions, and consequently, the problem cannot be modeled accurately. It is therefore critical to define a method that can identify the desired characteristics of the current system without accumulating extensive computation time. This thesis formulates an inverse approach using proper orthogonal decomposition (POD) with an accompanying ...


Raman Spectroscopy Of The Skeleton Of The Coral Acropora Cervicornis, Zachary C. Shepard Jan 2018

Raman Spectroscopy Of The Skeleton Of The Coral Acropora Cervicornis, Zachary C. Shepard

Honors Undergraduate Theses

Coral reefs are an important element of marine ecosystem that are critical to maintain a healthy environment. Unfortunately, in recent years coral reefs are doing poorly and many in parts of the ocean are simply dying. Therefore, study of coral’s structural response to external loads could answer what will happen with their structures, while they exhibit different types of loading. Therefore, the proposition of using in-situ micro-Raman spectroscopy to study skeletons of Acropora cervicornis was used. Coral skeleton samples I subjected to mechanical loading studied their vibrational properties by exciting the material with 532nm visible light. A uniaxial compressive ...


Optimal Sintering Temperature Of Ceria-Doped Scandia Stabilized Zirconia For Use In Solid Oxide Fuel Cells, Amanda K. Assuncao Jan 2018

Optimal Sintering Temperature Of Ceria-Doped Scandia Stabilized Zirconia For Use In Solid Oxide Fuel Cells, Amanda K. Assuncao

Honors Undergraduate Theses

Carbon emissions are known to cause decay of the Ozone layer in addition to creating pollutant, poisonous air. This has become a growing concern among scientists and engineers across the globe; if this issue is not addressed, it is likely that the Earth will suffer catastrophic consequences. One of the main culprits of these harmful carbon emissions is fuel combustion. Between vehicles, power plants, airplanes, and ships, the world consumes an extraordinary amount of oil and fuel which all contributes to the emissions problem. Therefore, it is crucial to develop alternative energy sources that minimize the impact on the environment ...


Investigation Of A Self-Powered Fontan Concept Using A Multiscale Computational Fluid-Structure Interaction Model, Kyle Beggs Jan 2018

Investigation Of A Self-Powered Fontan Concept Using A Multiscale Computational Fluid-Structure Interaction Model, Kyle Beggs

Electronic Theses and Dissertations

Congenital Heart Disease (CHD) occurs in about 1\% (40,000) of newborn babies each year in the United States alone. About 10.9\% (960) of whom suffer from Hypoplastic Left Heart Syndrome (HLHS) - a subset of CHD where children are born with a single-ventricle (SV). A series of three surgeries are carried out to correct HLHS culminating in the Fontan procedure where venous flow returns passively to the lungs. The current configuration for the Fontan results in elevated Central Venous Pressure (CVP), inadequate ventricular preload, and elevated Pulmonary Vascular Resistance (PVR) leading to a barrage of disease. To alleviate these ...


Adiabatic Film Cooling Effectiveness Of A Transpiration-Cooled Leading Edge Fabricated By Laser Additive Manufacturing, Luisana Calderon Jan 2018

Adiabatic Film Cooling Effectiveness Of A Transpiration-Cooled Leading Edge Fabricated By Laser Additive Manufacturing, Luisana Calderon

Electronic Theses and Dissertations

Laser additive manufacturing (LAM) is an emerging technology capable of fabricating complex geometries not possibly made by investment casting methods for gas turbine applications. LAM techniques consist of building parts in a layer-by-layer process by selectively melting metal powders. In the present study, a mock leading edge segment of a turbine blade fabricated by LAM of Inconel 718 powders is investigated. For this particular design, the traditional showerhead film cooling holes have been replaced by two strips containing engineered-porous regions with the purpose of simulating the effect of transpiration cooling. Transpiration cooling has been considered a promising external convective cooling ...


The Study Of An Impinging Unsteady Jet - Fluid Mechanics And Heat Transfer Analysis, Andrea Osorio Jan 2018

The Study Of An Impinging Unsteady Jet - Fluid Mechanics And Heat Transfer Analysis, Andrea Osorio

Electronic Theses and Dissertations

The high heat transfer capabilities of impinging jets have led to their widespread use in industrial applications, such as gas turbine cooling. These impinging jets are usually manufactured on the walls of super-alloy metals and are influenced by being positioned with a confined setting. Studies have been shown to enhance the heat transfer of impinging jets by fluctuating the flow which will be analyzed in this project with two designs. The first design is a self-sustaining stationary fluidic oscillator that causes a sweeping motion jet to impinge on the surface. This is investigated using Particle Image Velocimetry (PIV) to study ...


A Localized Blended Rbf Collocation Method For Effective Shock Capturing, Michael Harris Jan 2018

A Localized Blended Rbf Collocation Method For Effective Shock Capturing, Michael Harris

Electronic Theses and Dissertations

Solving partial differential equations (PDEs) can require numerical methods, especially for non-linear problems and complex geometry. Common numerical methods used today are the finite difference method (FDM), finite element method (FEM) and the finite volume method (FVM). These methods require a mesh or grid before a solution is attempted. Developing the mesh can require expensive preprocessing time and the quality of the mesh can have major effects on the solution. In recent years, meshless methods have become a research interest due to the simplicity of using scattered data points. Many types of meshless methods exist stemming from the spectral or ...


Fluid Dynamics Modeling And Sound Analysis Of A Bileaflet Mechanical Heart Valve, Fardin Khalili Jan 2018

Fluid Dynamics Modeling And Sound Analysis Of A Bileaflet Mechanical Heart Valve, Fardin Khalili

Electronic Theses and Dissertations

Cardiovascular disease (CVD) is one of the main causes of death in the world. Some CVD involve severe heart valve disease that require valve replacement. There are more than 300,000 heart valves implanted worldwide, and about 85,000 heart valve replacements in the US. Approximately half of these valves are mechanical. Artificial valves may dysfunction leading to adverse hemodynamic conditions. Understanding the normal and abnormal valve function is important as it help improve valve designs. Modeling of heart valve hemodynamics using computational fluid dynamics (CFD) provides a comprehensive analysis of flow, which can potentially help explain clinical observations and ...