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Full-Text Articles in Mechanical Engineering

Development Of An Indoor Multirotor Testbed For Experimentation On Autonomous Guidance Strategies, Kidus Guye Jan 2018

Development Of An Indoor Multirotor Testbed For Experimentation On Autonomous Guidance Strategies, Kidus Guye

Electronic Theses and Dissertations

Despite the vast popularity of rotary wing unmanned aerial vehicles and research centres that develop their guidance software, there are only a limited number of references that provide an exhaustive description of a step-by-step procedure to build-up a multirotor testbed. In response to such need, the first part of this thesis aims to describe, in detail, the complete procedure to establish and operate an autonomous multirotor unmanned aerial vehicle indoor experimental platform to test and validate guidance, navigation and control strategies. Both hardware and software aspects of the testbed are described to offer a complete understanding of the different aspects. …


Lcd 3d Printing Of A Photocurable Elastomer For Tissue Engineering, Beatriz Luiza De Souza Jan 2018

Lcd 3d Printing Of A Photocurable Elastomer For Tissue Engineering, Beatriz Luiza De Souza

Electronic Theses and Dissertations

Three-dimensional scaffolding is an emerging research area in biomedical and tissue engineering. Scaffolds provide the possibility of growing tissues in a controlled environment, with desired characteristics and properties towards a specific application. A new method to 3D print biodegradable and biocompatible material called Polyglycerol Sebacate Acrylate (PGSA) is demonstrated. PGSA is essentially an acrylated form of PGS using photoinitiator to become a photocurable resin suitable for liquid crystal display (LCD) 3D printing. PGSA was selected because its rheological and crosslinking behavior (and hence its mechanical properties) can be controlled by changes in curing time, temperature, and pressure. This material has …


Optimization Of Microfluidic Particle Separator Geometry Using Computational Fluid Dynamics, Joseph Petersen Jan 2018

Optimization Of Microfluidic Particle Separator Geometry Using Computational Fluid Dynamics, Joseph Petersen

Electronic Theses and Dissertations

Computational fluid dynamics software was used to simulate the motion of circulating tumor cells in a variety of microfluidic cell isolation devices. Design of several novel microfluidic cell isolation devices was aided by viewing streamlines of fluid in devices in simulation. Devices that performed best in simulation used 5-micrometer wide guiding channels to guide cells to the capture location in the device. While these devices performed better than other devices in simulation and captured all particles regardless of position along inlet, experimental results differ from simulation.


Nonlinear Stochastic Filtering For Online State Of Charge And Remaining Useful Life Estimation Of Lithium-Ion Battery, Suresh Daravath Jan 2018

Nonlinear Stochastic Filtering For Online State Of Charge And Remaining Useful Life Estimation Of Lithium-Ion Battery, Suresh Daravath

Electronic Theses and Dissertations

Battery state monitoring is one of the key techniques in Battery Management System (BMS). Accurate estimation can help to improve the system performance and to prolong the battery lifetime. The main challenges for the state online estimation of Li-ion batteries are the flat characteristic of open circuit voltage (OCV) with the function of the state of charge. Hence, the focus of this thesis study is to estimation of the state of charge (SOC) of Li-ion with high accuracy, more robustness. A 2nd order RC equivalent circuit model is adapted to battery model for simulation, mathematical model analysis, and dynamics characteristic …


Evaluation Of The Mechanical Properties Of 3d Printed Carbon Fiber Composites, Max James Sauer Jan 2018

Evaluation Of The Mechanical Properties Of 3d Printed Carbon Fiber Composites, Max James Sauer

Electronic Theses and Dissertations

Studies have been done involving the use of carbon fiber as a reinforcement for three dimensional (3D) printed parts. The Markforged Mark Two is a commercial grade 3D printer capable of printing parts reinforced with continuous fibers such as carbon fiber, Kevlar, and fiberglass. Short Carbon Fiber Composite tensile specimen were printed on both a Markforged Mark Two and Flashforge Creator Pro using Markforged Onyx filament. The results of these parts were compared for their tensile properties, dimensional accuracy, and mass estimates. The Creator Pro was capable of producing stronger parts on average, while the Mark Two produced more dimensionally …


Topology Optimization Of Lightweight Structural Composites Inspired By Cuttlefish Bone, Varun Kumar Gadipudi Jan 2018

Topology Optimization Of Lightweight Structural Composites Inspired By Cuttlefish Bone, Varun Kumar Gadipudi

Electronic Theses and Dissertations

Lightweight material structure is a crucial subject in product design. The lightweight material has high strength to weight proportion which turns into an immense fascination and a territory of investigation for the researchers as its application is wide and expanding consistently. Lightweight composite material design is accomplished by choice of the cellular structure and its optimization. Cellular structure is utilized as it has wide multifunctional properties with lightweight characteristics. Unless it has been topologically optimized, each part in a assembly most likely weighs more than it needs to. Additional weight implies abundance materials are being utilized, loads on moving parts …


Bio-Mimetic Design With 3d Printable Composites, Ramya Mitra Patnam Damodaram Jan 2018

Bio-Mimetic Design With 3d Printable Composites, Ramya Mitra Patnam Damodaram

Electronic Theses and Dissertations

Weight and stiffness are key factors in the advancement of materials and parts for use in numerous industries. Lightweight cellular structures are broadly utilized for this reason. However, these structures must satisfy several key constraints: they should be light yet structurally safe, sustainable in different loading conditions, resource efficient and easy to maintain. Bio-inspired materials/structures which results in desirable material features are a significant inspiration for engineered cellular structures. Cellular structures can be designed to have multifunctional properties along with lightweight characteristics. Currently, these structures with high strength to weight ratio are widely applied in many fields such as automotive, …


Effect Of Poisson’S Ratio On Young's Modulus Characterization Using Ultrasonic Technique By Modeling, Michael Onyetube Jan 2018

Effect Of Poisson’S Ratio On Young's Modulus Characterization Using Ultrasonic Technique By Modeling, Michael Onyetube

Electronic Theses and Dissertations

The past 27 years has witnessed a revolutionary growth in the progress of material development and application in almost all industry and business sectors, and this seems to be continuing even today. So many material-driven innovations have enabled the global spread in technology and improvements in capability, ranging from communications to aerospace and healthcare, to automotive and agriculture. Mechanical behavior of elastic materials is modeled by two main independent constants; Young’s modulus and Poisson’s ratio. An accurate measurement of both constants is necessary in most engineering applications, for example, the standard materials used for the calibration of some equipment, quality …


Development Of Material For 3d Printed Habitats With Extraplanetary Applications, Taylor Wait Jan 2018

Development Of Material For 3d Printed Habitats With Extraplanetary Applications, Taylor Wait

Electronic Theses and Dissertations

3D printing, also called Additive Manufacturing, has increasingly become a focus for research because of the potential to replace complicated assemblies or complex parts with a single printed item. The space industry is very interesting in studying 3d printing with parts being tested and used on rockets, a 3D printer being installed at the International Space Station and is being developed for use in manned exploration of extraplanetary bodies to build habitats. To encourage teams from around the world to develop technologies and materials for autonomous habitat construction using minimal Earth exports, NASA created the 3D Printed Habitat Challenge. NASA …


Simulation Of Gas Dynamic Cold Spray Process, Sai Rajkumar Vadla Jan 2018

Simulation Of Gas Dynamic Cold Spray Process, Sai Rajkumar Vadla

Electronic Theses and Dissertations

The utilization of computational fluid dynamics (CFD) as a study tool in the aerodynamics and turbomachinery industry reinforces efficiency in the design of aircraft or for understanding the flow through pipes. CFD offer tools to model different geometries and perform a more extensive study of the flow phenomena. This gives the opportunity to model a variety of geometries and analyze their behavior under different operating conditions. A similar approach can be applied to coating technologies. Coating technologies play an essential role in the manufacturing industry. Their ability to form layers of specific materials onto engineering components to enhance mechanical and …


A Quantitative Environmental Assessment Of Incorporating Torrefaction Into Farming Enterprises In Eastern South Dakota, Dinesh Fuyal Jan 2018

A Quantitative Environmental Assessment Of Incorporating Torrefaction Into Farming Enterprises In Eastern South Dakota, Dinesh Fuyal

Electronic Theses and Dissertations

The use of renewable energy sources has been increasing in the recent years due to population growth and environmental concerns. Biomass is a promising energy source that can be used to produce biofuels or torrefied pellets. Torrefied biomass may be used in power plants, industrial and residential heating, feedstocks for gasification, air and water filtrating, and soil amendment. The interest of torrefied pellets as energy sources for various applications has been increased in the recent years due to the concerns about energy security and environmental issues. This study focuses on the economic and environmental assessment of agricultural feedstocks like corn …


Simulation Of An Ethylene Flame With Turbulence, Soot And Radiation Modeling, Santu Golder Jan 2018

Simulation Of An Ethylene Flame With Turbulence, Soot And Radiation Modeling, Santu Golder

Electronic Theses and Dissertations

This thesis will investigate soot models that are available in commercial codes. We will look at the effect of turbulence models, gravity, soot models and radiation. Simulations will be compared to Coppalle and Joyeux [1]. The flame is an ethylene air diffusion flame at a Reynolds number of 5700. Simulations show the SST turbulence model, one-step soot model and Rosseland radiation model including gravity agree well with experimental data (temperature and soot). Flamelet soot modeling from Carbonell et al. [2] and flamelet radiation modeling from Doom [3] has been incorporated and compared as well.


Simulation Of Non-Premixed Ethylene-Air Crossflow Jet Flame, Jennifer Onyinye Chikelu Jan 2018

Simulation Of Non-Premixed Ethylene-Air Crossflow Jet Flame, Jennifer Onyinye Chikelu

Electronic Theses and Dissertations

Computational fluid dynamics tool has been employed in the past to determine and analyze efficiency or performance in combustion engines and for combustion analysis. This paper represents a systematic investigation on the best model predicts the temperature and soot production in coflow jet flame, by applying various RANS turbulent model, soot models and radiation models in presence or absence of gravity. It also applies this model predicted in crossflow jet flame and investigates the velocity ratio (ratio of the velocity of fuel jet to the velocity of air stream) variation effect on temperature and soot production. ANSYS-Fluent CFD software tool …


Simulation Of Different Rib Shapes In Square Channel, Md Sahedul Islam Jan 2018

Simulation Of Different Rib Shapes In Square Channel, Md Sahedul Islam

Electronic Theses and Dissertations

This study investigates heat transfer and pressure drop for rib-roughened square channel without bleed. To optimize the shape of rib, CFD tools were used to model and simulate channel flow with a variety of rib angles and geometries. To validate simulations and determine the turbulence model, experimental results for two-pass channels with ribs at 45˚ angles with BR = 0 and Re = 25,000 was compared. It was found after conducting simulations with different turbulence models that SST turbulence model gave the best results.


Optimization Of Heat Sinks In A Range Of Configurations., Archibald Allswell Amoako Jan 2018

Optimization Of Heat Sinks In A Range Of Configurations., Archibald Allswell Amoako

Electronic Theses and Dissertations

In this study, different heatsink geometries used for electronic cooling are studied and compared to each other to determine the most efficient. The goal is to optimize heat transfer of the heat sinks studied in a range of configuration based on fin geometry. Heat sinks are thermal conductive material devices designed to absorb and disperse heat from high-temperature objects (e.g. Computer CPU). Common materials used in the manufacturing of heat sinks are aluminum and copper due to their relatively high thermal conductivity and lightweight [1]. Aluminum is used as the material for the heatsinks studied in this research project. To …


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 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 …


Multi-Scale Fluid-Structure Interaction Model Analysis Of Patient-Specific Geometry For Optimization Of Lvad Outflow Graft Implantation: An Investigation Aimed At Reducing Stroke Risk, Ray Prather Jan 2018

Multi-Scale Fluid-Structure Interaction Model Analysis Of Patient-Specific Geometry For Optimization Of Lvad Outflow Graft Implantation: An Investigation Aimed At Reducing Stroke Risk, Ray Prather

Electronic Theses and Dissertations

A Left Ventricular Assist Device (LVAD), is a mechanical pump capable of providing circulatory myocardium relief when used as bridge-to-transplantation by reducing the workload of a failing heart, with the additional bonus of allowing for cardiac recovery when used as destination therapy. The newer generations of continuous flow VADs are essentially axial or radial flow pumps, and while these devices are capable their efficiency depends upon fluid composition and flow field patterns. The most devastating complication of VAD therapy is caused by embolization of thrombi formed within the LVAD or inside the heart into the brain leading to stroke. Anticoagulation …


Ignition Studies Of Oxy-Syngas/Co2 Mixtures Using Shock Tube For Cleaner Combustion Engines, Samuel Barak Jan 2018

Ignition Studies Of Oxy-Syngas/Co2 Mixtures Using Shock Tube For Cleaner Combustion Engines, Samuel Barak

Electronic Theses and Dissertations

In this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2 cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% - 85% by volume. A 10% fuel concentration was consistently used throughout the experiments. This study looked at the effects of changing 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 …


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 …


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 …


Hosting Capacity Optimization In Modern Distribution Grids, Mansoor T. Alturki Jan 2018

Hosting Capacity Optimization In Modern Distribution Grids, Mansoor T. Alturki

Electronic Theses and Dissertations

The availability of distributed renewable energy resources and the anticipated increase in new types of loads are changing the way electricity is being produced and supplied to consumers. This shift is moving away from a network delivering power solely from centralized power plants towards a decentralized network which supplements its power production by incorporating local distributed generators (DGs). However, the increased integration of DGs into existing distribution networks is impacting their behavior in terms of voltage profile, reliability, and power quality. To determine the maximum amount of DG that distribution grids can accommodate the concept of hosting capacity is introduced. …


Automated Cfd Optimization To Maximize Wind Farms Performance And Land Use, Rafael Valotta Rodrigues Jan 2018

Automated Cfd Optimization To Maximize Wind Farms Performance And Land Use, Rafael Valotta Rodrigues

Electronic Theses and Dissertations

In this research, a computational system was designed to analyze and optimize the layout of wind farms under variable operational conditions. At first, a wind turbine computational fluid dynamic (CFD) model was developed covering the near wake. The near wake flow field was validated against near wake velocity data from the MEXICO experiment. The CFD simulation demonstrated that the tip speed ratio and the pitch angle greatly influence the near wake behavior, affecting the velocity deficit and the turbulence intensity profile in this region. The CFD model was extended to cover the far wake, aiming to become a computational tool …


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 support therapeutic …


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 biomechanical …


Characterization Of Fast Flames For Turbulence-Induced Deflagration To Detonation Transition, Jessica Chambers Jan 2018

Characterization Of Fast Flames For Turbulence-Induced Deflagration To Detonation Transition, Jessica Chambers

Electronic Theses and Dissertations

One of the fundamental mechanisms for detonation initiation is turbulence driven deflagration to detonation transition (TDDT). The research experimentally explores the propagation dynamics demonstrated by fast deflagrated flames interacting with highly turbulent reactants. Fast flames produce extremely high turbulent flame speeds values, increased levels of compressibility and develop a runaway mechanism that leads to TDDT. The flame structural dynamics and reacting flow field are characterized using simultaneous high-speed particle image velocimetry, chemiluminescence, and Schlieren measurements. The investigation classifies the fast flame propagation modes at various regimes. The study further examines the conditions for a turbulent fast flame at the boundary …


A Study On The Plasticity And Fracture Of Aisi 4340 Steel Under Different Loading Conditions Considering Heat Treatment And Micromechanics, Sami Ghazali Jan 2018

A Study On The Plasticity And Fracture Of Aisi 4340 Steel Under Different Loading Conditions Considering Heat Treatment And Micromechanics, Sami Ghazali

Electronic Theses and Dissertations

Accurate predictions of material strength under different loading conditions with large plastic deformation and ductile fracture are of great importance. This dissertation aims to develop an essential understanding of ductile fracture of AISI 4340 steel alloy using both empirical and micromechanics based models. For this purpose, 29 specimens of different geometries with different heat-treatments were designed to investigate the effects of stress states. These specimens are: (a) 13 round bars with different notches (axial symmetric tension); (b) 13 flat grooved specimens with different grooves; (c) 3 small round cylinders. Mechanical tests up to fracture were conducted on these specimens to …


Energy-Optimal Guidance Of An Auv Under Flow Uncertainty And Fluid-Particle Interaction, Demuni Singith De Zoysa Abeysiriwardena Jan 2018

Energy-Optimal Guidance Of An Auv Under Flow Uncertainty And Fluid-Particle Interaction, Demuni Singith De Zoysa Abeysiriwardena

Electronic Theses and Dissertations

The work presented gives an energy-optimal solution to the guidance problem of an AUV. The presented guidance methods are for lower level control of AUV paths, facilitating existing global planning methods to be carried out comparatively more efficiently. The underlying concept is to use the energy of fluid flow fields the AUVs are navigating to extend the duration of missions. This allows gathering of comparatively more data with higher spatio-temporal resolution. The problem is formulated for a generalized two dimensional uniform flow field given a fixed final time and free end states. This allows the AUVs to navigate to certain …


Mechanisms Of Flame Extinction For Bluff Body Stabilized Flames With Influences Of Pressure Gradient Tailoring, Anthony Morales Jan 2018

Mechanisms Of Flame Extinction For Bluff Body Stabilized Flames With Influences Of Pressure Gradient Tailoring, Anthony Morales

Electronic Theses and Dissertations

Flame extinction continues to hinder the performance of combustion technologies used in propulsion systems and power generating turbomachinery. Within these applications, there is a crucial need to improve energy output while minimizing harmful environmental impacts. Lean combustion helps attain these goals by minimizing fuel costs and reducing NOx emissions. However, operating at lean conditions increases the likelihood of flame extinction; the flame becomes more susceptible to hydrodynamic instabilities which can induce global blowout and termination of the combustion process. The work in this thesis is focused on identifying the mechanisms of flame extinction and controlling these mechanisms via pressure gradient …