# Mechanical Engineering Commons™

Articles 1 - 30 of 193

## Full-Text Articles in Mechanical Engineering

#### Design And Testing Of A Wind Energy Harnessing System For Forced Convective Drying Of Grain In Low Wind Speed, Warm And Humid Climates, Francis Akumabi Agbali

##### Theses and Dissertations--Biosystems and Agricultural Engineering

Forced convective drying using a wind turbine mechanically connected to a ventilation fan was hypothesized for low cost and rapid grain drying in developing countries. The idea was tested using an expandable wind turbine blade system with variable pitch, at low wind speeds in a wind tunnel. The design was based on empirical and theoretical models embedded in a graphical user interface (GUI) created to estimate airflow-power requirements for drying ear corn. Output airflow (0.0016 - 0.0052 m3kg-1s-1) increased within the study wind speed range (2.0 - 5.5 m/s). System efficiency peak ...

Jan 2019

#### Dust Transportation And Settling Within The Mine Ventilation Network, Anand Kumar

##### Theses and Dissertations--Mining Engineering

Dust is ubiquitous in underground mine activities. Continuous inhalation of dust could lead to irreversible occupational diseases. Dust particles of size lower than 75.0 µm, also known as float coal dust, can trigger a coal dust explosion following a methane ignition. Ventilation air carries the float coal dust from the point of production to some distance before it’s deposited on the surfaces of underground coal mine. Sources of dust are widely studied, but study of dust transportation has been mainly based on experimental data and simplified models. An understanding of dust transportation in the mine airways is ...

#### Quantification Of Myocardial Mechanics In Left Ventricles Under Inotropic Stimulation And In Healthy Right Ventricles Using 3d Dense Cmr, Zhan-Qiu Liu

##### Theses and Dissertations--Mechanical Engineering

Statistical data from clinical studies indicate that the death rate caused by heart disease has decreased due to an increased use of evidence-based medical therapies. This includes the use of magnetic resonance imaging (MRI), which is one of the most common non-invasive approaches in evidence-based health care research. In the current work, I present 3D Lagrangian strains and torsion in the left ventricle of healthy and isoproterenol-stimulated rats, which were investigated using Displacement ENcoding with Stimulated Echoes (DENSE) cardiac magnetic resonance (CMR) imaging. With the implementation of the 12-segment model, a detailed profile of regional cardiac mechanics was reconstructed for ...

Development Of A Muffler Insertion Loss Flow Rig, Jonathan Chen Jan 2019

#### Development Of A Muffler Insertion Loss Flow Rig, Jonathan Chen

##### Theses and Dissertations--Mechanical Engineering

Mufflers and silencers are commonly used to attenuate noise sources such as internal combustion engines and HVAC systems. Typically, these environments contain mean flow that can affect the acoustic properties of the muffler components and may produce flow generated noise. To characterize the muffler performance, common metrics such as insertion and transmission loss and noise reduction are used in industry. Though transmission loss without flow is often measured and is a relatively simple bench top experiment and useful for model validation purposes, mean flow can significantly affect the muffler performance. There are a few existing and commercial transmission loss rigs ...

Determination Of Acoustic Radiation Efficiency Via Particle Velocity Sensor With Applications, Steven Conner Campbell Jan 2019

#### Determination Of Acoustic Radiation Efficiency Via Particle Velocity Sensor With Applications, Steven Conner Campbell

##### Theses and Dissertations--Mechanical Engineering

Acoustic radiation efficiency is defined as the ratio of sound power radiated to the surface vibration power of a piston with equivalent surface area. It has been shown that the radiation efficiency is maximized and may exceed unity when the structural and acoustic wavelengths are approximately equal. The frequency at which this occurs is called the critical frequency and can be shifted with structural modifications. This has proven to be an effective way to reduce noise. The standard radiation efficiency measurement is comprised of an intensity scan for sound power measurement and accelerometer array for spatially averaged vibration determination. This ...

#### Enhanced Surface Integrity With Thermally Stable Residual Stress Fields And Nanostructures In Cryogenic Processing Of Titanium Alloy Ti-6al-4v, James R. Caudill

##### Theses and Dissertations--Mechanical Engineering

Burnishing is a chipless finishing process used to improve surface integrity by severe plastic deformation (SPD) of surface asperities. As surface integrity in large measure defines the functional performance and fatigue life of aerospace alloys, burnishing is thus a means of increasing the fatigue life of critical components, such as turbine and compressor blades in gas turbine engines. Therefore, the primary objective of this dissertation is to characterize the burnishing-induced surface integrity of Ti-6Al-4V alloy in terms of the implemented processing parameters. As the impact of cooling mechanisms on surface integrity from SPD processing is largely unexplored, a particular emphasis ...

Jan 2019

#### Quantification Of Papillary Muscle Motion And Mitral Regurgitation After Myocardial Infarction, Connor R. Ferguson

##### Theses and Dissertations--Mechanical Engineering

Change in papillary muscle motion as a result of left ventricular (LV) remodeling after posterolateral myocardial infarction is thought to contribute to ischemic mitral regurgitation. A finite element (FE) model of the LV was created from magnetic resonance images acquired immediately before myocardial infarction and 8 weeks later in a cohort of 12 sheep. Severity of mitral regurgitation was rated by two-dimensional echocardiography and regurgitant volume was estimated using MRI. Of the cohort, 6 animals (DC) received hydrogel injection therapy shown to limit ventricular remodeling after myocardial infarction while the control group (MI) received a similar pattern of saline injections ...

Jan 2019

#### Design And Process Of 3d-Printed Parts Using Composite Theory, Jordan Garcia

##### Theses and Dissertations--Mechanical Engineering

3D printing is a revolutionary manufacturing method that allows the productions of engineering parts almost directly from modeling software on a computer. With 3D printing technology, future manufacturing could become vastly efficient. However, it is observed that the procedures used in 3D printing differ substantially among the printers and from those used in conventional manufacturing. In this thesis, the mechanical properties of engineering products fabricated by 3D printing were comprehensively evaluated and then compared with those made by conventional manufacturing. Three open-source 3D printers, i.e., the Flash Forge Dreamer, the Tevo Tornado, and the Prusa, were used to fabricate ...

#### Implementation And Analysis Of True Lean In A Startup Company By Using Pdca Model, A Case Study In A Manufacturing Venture, Ankit Jangid

##### Theses and Dissertations--Manufacturing Systems Engineering

The purpose of this research is to implement and analyze the true lean transformation in a manufacturing start-up organization. Often, lean transformations are observed in developed manufacturing organizations having sophisticated production lines and numerous employees, where lean tools are utilized to reduce waste while increasing profit. However, this type of transformation is narrowly focused on quantifiable process results and falls short of the ultimate goal, establishing a true lean culture within the organization. As a result, it is recommended that true lean principles, philosophies, culture, operations environment and tools be applied at the very beginning stages of an organization, or ...

#### Oxidative Degradation Of Lignin And Investigation Of Utilization Of Lignin-Derived Materials As Building Blocks For Epoxy Resins, Zhen Fang

##### Theses and Dissertations--Chemistry

Lignin, the second most abundant biopolymer on earth, is potentially a replaceable source for bulky fuels and chemical feedstocks. There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages but relatively few reports of how those methods affect other linkages that are present in lignin. We investigated how the β-1 and β-5 linkages respond under oxidative conditions proposed for lignin deconstruction based on their effect on β-O-4 linkages. Mechanochemical treatment of lignin can greatly improve the yield of monomer products and we applied a mechanochemical approach, using powerful ring-and-puck milling to promote lignin degradation. Along with ...

Jan 2019

#### An Analysis Of Resistance Spot Weld Quality Based On Acoustic And Electrical Signatures, Ivan Charles Butler

##### Theses and Dissertations--Manufacturing Systems Engineering

The union of a set of materials by way of Resistance Spot Welding is designed so that once fused together, a substantial amount of intentional, external force must be applied to separate the contents. Therefore, Resistance Spot Welding is often the preferred fusion method in high-volume manufacturing processes. The result of Resistance Spot Welding however is the formation of a weld nugget which is not visible to the naked eye. Destructive and/or ultrasonic methods applied off-line must be used to determine the quality of each weld; both inefficient and expensive processes. The following research analyzes the data fed back ...

Jan 2019

#### A Computational Study Of Patch Implantation And Mitral Valve Mechanics, Dara Singh

##### Theses and Dissertations--Mechanical Engineering

Myocardial infarction (i.e., a heart attack) is the most common heart disease in the United States. Mitral valve regurgitation, or the backflow of blood into the atrium from the left ventricle, is one of the complications associated with myocardial infarction. In this dissertation, a validated model of a sheep heart that has suffered myocardial infarction has been employed to study mitral valve regurgitation. The model was rebuilt with the knowledge of geometrical changes captured with MRI technique and is assigned with anisotropic, inhomogeneous, nearly incompressible and highly non-linear material properties. Patch augmentation was performed on its anterior leaflet, using ...

Jan 2019

#### Hot-Wire Anemometer Measurements Of Atmospheric Surface Layer Turbulence Via Unmanned Aerial Vehicle, Caleb A. Canter

##### Theses and Dissertations--Mechanical Engineering

An instrumented unmanned aerial vehicle (UAV) was developed and employed to observe the full range of turbulent motions that exist within the inertial subrange of atmospheric surface layer turbulence. The UAV was host to a suite of pressure, temperature, humidity, and wind sensors which provide the necessary data to calculate the variety of turbulent statistics that characterize the flow. Flight experiments were performed with this aircraft, consisting of a large square pattern at an altitude of 100 m above ground level. In order to capture the largest turbulent scales it was necessary to maximize the size of the square pattern ...

Jan 2019

#### Indoor-Wireless Location Techniques And Algorithms Utilizing Uhf Rfid And Ble Technologies, Ann M. Whitney

##### Theses and Dissertations--Mechanical Engineering

The work presented herein explores the ability of Ultra High Frequency Radio Frequency (UHF RF) devices, specifically (Radio Frequency Identification) RFID passive tags and Bluetooth Low Energy (BLE) to be used as tools to locate items of interest inside a building. Localization Systems based on these technologies are commercially available, but have failed to be widely adopted due to significant drawbacks in the accuracy and reliability of state of the art systems. It is the goal of this work to address that issue by identifying and potentially improving upon localization algorithms.

The work presented here breaks the process of localization ...

Circulation Dependence Of The Interaction Between A Wing-Tip Vortex And Turbulence, Farshid Najarzadegan Jan 2019

#### Circulation Dependence Of The Interaction Between A Wing-Tip Vortex And Turbulence, Farshid Najarzadegan

##### Theses and Dissertations--Mechanical Engineering

Vortices are present in many fluid flows and depending on the context they may be either beneficial or harmful for different systems or processes. Planar particle image velocimetry was used to examine the vortex evolution and its decay under different turbulence intensities and vortex circulation. The vortex decayed faster in the presence of high turbulence intensity. Vortex trajectories were impacted by turbulence intensity and vortex strength. Trajectories with no turbulence intensity had less variation. The vortex wandering amplitude decreased with growth of vortex strength. The vortex decay was confined to the core of the vortex, with the tangential velocity at ...

Dec 2018

#### Numerical Simulations Of Premixed Flames Of Multi Component Fuels/Air Mixtures And Their Applications, Essa Kh I J Salem

##### Theses and Dissertations--Mechanical Engineering

Combustion has been used for a long time as a means of energy extraction. However, in the recent years there has been further increase in air pollution, through pollutants such as nitrogen oxides, acid rain etc. To solve this problem, there is a need to reduce carbon and nitrogen oxides through lean burning, fuel dilution and usage of bi-product fuel gases. A numerical analysis has been carried out to investigate the effectiveness of several reduced mechanisms, in terms of computational time and accuracy. The cases were tested for the combustion of hydrocarbons diluted with hydrogen, syngas, and bi-product fuel in ...

Jan 2018

#### Lower Back Biomechanics At Non-Chronic Stage Of Low Back Pain, Iman Shojaei

##### Theses and Dissertations--Biomedical Engineering

Prior studies have reported differences in lower back biomechanics during activities of daily living between individuals with and without chronic low back pain (LBP). Nevertheless, the literature on lower back biomechanics of patients with non-chronic LBP is scant. Therefore, the objective of this study, as the first step towards future prospective studies, was to investigate the lower back biomechanics in patients with non-chronic LBP. Case-control studies were conducted wherein measures of lumbo-pelvic coordination during bending and return tasks as well as measures of mechanical demand on the lower back during lifting tasks in the sagittal plane were investigated between patients ...

#### Dust Control Examination Using Computational Fluid Dynamics Modeling And Laboratory Testing Of Vortecone And Impingement Screen Filters, Ashish R. Kumar

##### Theses and Dissertations--Mining Engineering

Heavy industries, such as mining, generate dust in quantities that present an occupational health hazard. Prolonged exposure to the respirable dust has been found to result in many irreversible occupational ailments in thousands of miners. In underground mining applications, a variety of scrubbing systems are used to remove dust near the zones of generation. However, the wire-mesh type fibrous screens in the flooded-bed dust scrubbers used on continuous miners, are prone to clogging due to the accumulation of dust particles. This clogging results in a reduced capture efficiency and a higher exposure to the personnel. This research establishes the Vortecone ...

Jan 2018

#### Assessing The Spatial Accuracy And Precision Of Lidar For Remote Sensing In Agriculture, Surya Saket Dasika

##### Theses and Dissertations--Biosystems and Agricultural Engineering

The objective of this whole study was to evaluate a LiDAR sensor for high-resolution remote sensing in agriculture. A linear motion system was developed to precisely control the dynamics of LiDAR sensor in effort to remove uncertainty in the LiDAR position/velocity while under motion. A user control interface was developed to operate the system under different velocity profiles and log LiDAR data synchronous to the motion of the system. The LiDAR was then validated using multiple test targets with five different velocity profiles to determine the effect of sensor velocity and height above a target on measurement error. The ...

Jan 2018

#### Characterization Of Rotary Bell Atomizers Through Image Analysis Techniques, Jacob E. Wilson

##### Theses and Dissertations--Mechanical Engineering

Three methods were developed to better understand and characterize the near-field dynamic processes of rotary bell atomization. The methods were developed with the goal of possible integration into industry to identify equipment changes through changes in the primary atomization of the bell. The first technique utilized high-speed imaging to capture qualitative ligament breakup and, in combination with a developed image processing technique and PIV software, was able to gain statistical size and velocity information about both ligaments and droplets in the image data. A second technique, using an Nd:YAG laser with an optical filter, was used to capture size ...

Bayesian-Integrated System Dynamics Modelling For Production Line Risk Assessment, Sudhir Punyamurthula Jan 2018

#### Bayesian-Integrated System Dynamics Modelling For Production Line Risk Assessment, Sudhir Punyamurthula

##### Theses and Dissertations--Mechanical Engineering

Companies, across the globe are concerned with risks that impair their ability to produce quality products at a low cost and deliver them to customers on time. Risk assessment, comprising of both external and internal elements, prepares companies to identify and manage the risks affecting them. Although both external/supply chain and internal/production line risk assessments are necessary, internal risk assessment is often ignored. Internal risk assessment helps companies recognize vulnerable sections of production operations and provide opportunities for risk mitigation.

In this research, a novel production line risk assessment methodology is proposed. Traditional simulation techniques fail to capture ...

Jan 2018

#### Laminar And Turbulent Study Of Combustion In Stratified Environments Using Laser Based Measurements, Stephen William Grib

##### Theses and Dissertations--Mechanical Engineering

Practical gas turbine engine combustors create extremely non-uniform flowfields, which are highly stratified making it imperative that similar environments are well understood. Laser diagnostics were utilized in a variety of stratified environments, which led to temperature or chemical composition gradients, to better understand autoignition, extinction, and flame stability behavior. This work ranged from laminar and steady flames to turbulent flame studies in which time resolved measurements were used.

Edge flames, formed in the presence of species stratification, were studied by first developing a simple measurement technique which is capable of estimating an important quantity for edge flames, the advective heat ...

#### Numerical And Experimental Techniques For Assessing The Acoustic Performance Of Duct Systems Above The Plane Wave Cutoff Frequency, Kangping Ruan

##### Theses and Dissertations--Mechanical Engineering

This research deals with determining the acoustic attenuation of heating, ventilation, and air conditioning (HVAC) ductwork. A finite element approach was developed for calculating insertion loss and breakout transmission loss. Procedures for simulating the source and receiving rooms were developed and the effect of structureborne flanking was included. Simulation results have been compared with measurements from the literature and the agreement is very good. With a good model in place, the work was extended in three ways. 1) Since measurements on full-scale equipment are difficult, scale modeling rules were developed and validated. 2) Two different numerical approaches were developed for ...

The Kentucky Re-Entry Universal Payload System (Krups): Sub-Orbital Flights, James Devin Sparks Jan 2018

#### The Kentucky Re-Entry Universal Payload System (Krups): Sub-Orbital Flights, James Devin Sparks

##### Theses and Dissertations--Mechanical Engineering

The Kentucky Re-entry Universal Payload System (KRUPS) is an adaptable testbed for atmosphere entry science experiments, with an initial application to thermal protection systems (TPS). Because of the uniqueness of atmospheric entry conditions that ground testing is unable to replicate, scientists principally rely on numerical models for predicting entry conditions. The KRUPS spacecraft, developed at the University of Kentucky, provides an inexpensive means of obtaining validation data to verify and improve these models.

To increase the technology readiness level (TRL) of the spacecraft, two sub-orbital missions were developed. The first mission, KUDOS, launched August 13th, 2017 on a Terrier-Improved Malamute ...

#### Assisted Development Of Mesophase Pitch With Dispersed Graphene And Its Resulting Carbon Fibers, Aaron Owen

##### Theses and Dissertations--Mechanical Engineering

The efficacy of dispersed reduced graphene oxide (rGO) as a nucleation site for the growth of mesophase in an isotropic pitch was investigated and quantified in this study. Concentrations of rGO were systematically tested in an isotropic petroleum and coal-tar pitch during thermal treatments and compared to pitch without rGO. The mesophase content of each thermally treated pitch was quantified by polarized light point counting. Further characterization of softening temperature and insolubles were quantified. Additionally, the pitches with and without rGO were melt spun, graphitized, and tensile tested to determine the effects of rGO on graphitized fiber mechanical properties and ...

Jan 2018

#### Design And Analysis Of A 3d-Printed, Thermoplastic Elastomer (Tpe) Spring Element For Use In Corrective Hand Orthotics, Kevin Thomas Richardson

##### Theses and Dissertations--Mechanical Engineering

This thesis proposes an algorithm that determine the geometry of 3D-printed, custom-designed spring element bands made of thermoplastic elastomer (TPE) for use in a wearable orthotic device to aid in the physical therapy of a human hand exhibiting spasticity after stroke. Each finger of the hand is modeled as a mechanical system consisting of a triple-rod pendulum with nonlinear stiffness at each joint and forces applied at the attachment point of each flexor muscle. The system is assumed quasi-static, which leads to a torque balance between the flexor tendons in the hand, joint stiffness and the design force applied to ...

Attitude Control On So(3) With Piecewise Sinusoids, Shaoqian Wang Jan 2018

#### Attitude Control On So(3) With Piecewise Sinusoids, Shaoqian Wang

##### Theses and Dissertations--Mechanical Engineering

This dissertation addresses rigid body attitude control with piecewise sinusoidal signals. We consider rigid-body attitude kinematics on SO(3) with a class of sinusoidal inputs. We present a new closed-form solution of the rotation matrix kinematics. The solution is analyzed and used to prove controllability. We then present kinematic-level orientation-feedback controllers for setpoint tracking and command following.

Next, we extend the sinusoidal kinematic-level control to the dynamic level. As a representative dynamic system, we consider a CubeSat with vibrating momentum actuators that are driven by small $\epsilon$-amplitude piecewise sinusoidal internal torques. The CubeSat kinetics are derived using Newton-Euler's ...

Discrete-Time Adaptive Control Algorithms For Rejection Of Sinusoidal Disturbances, Mohammadreza Kamaldar Jan 2018

#### Discrete-Time Adaptive Control Algorithms For Rejection Of Sinusoidal Disturbances, Mohammadreza Kamaldar

##### Theses and Dissertations--Mechanical Engineering

We present new adaptive control algorithms that address the problem of rejecting sinusoids with known frequencies that act on an unknown asymptotically stable linear time-invariant system. To achieve asymptotic disturbance rejection, adaptive control algorithms of this dissertation rely on limited or no system model information. These algorithms are developed in discrete time, meaning that the control computations use sampled-data measurements. We demonstrate the effectiveness of algorithms via analysis, numerical simulations, and experimental testings. We also present extensions to these algorithms that address systems with decentralized control architecture and systems subject to disturbances with unknown frequencies.

Pressure-Driven Stabilization Of Capacitive Deionization, Landon S. Caudill Jan 2018

#### Pressure-Driven Stabilization Of Capacitive Deionization, Landon S. Caudill

##### Theses and Dissertations--Mechanical Engineering

The effects of system pressure on the performance stability of flow-through capacitive deionization (CDI) cells was investigated. Initial data showed that the highly porous carbon electrodes possessed air/oxygen in the micropores, and the increased system pressure boosts the gases solubility in saline solution and carries them out of the cell in the effluent. Upon applying a potential difference to the electrodes, capacitive-based ion adsorption occurs in competition with faradaic reactions that consume oxygen. Through the addition of backpressure, the rate of degradation decreases, allowing the cell to maintain its salt adsorption capacity (SAC) longer. The removal of oxygen from ...

Jan 2018

#### Characterization Of The Shape Memory Behavior Of High Strength Nitihfpd Shape Memory Alloys, Guher P. Toker

##### Theses and Dissertations--Mechanical Engineering

NiTiHf alloys have emerged as potential materials for applications requiring high transformation temperatures (> 100 °C) with high strength and work output. Although they have high transformation temperatures, their low damping capacity, brittleness and poor superelastic responses (of Ti-rich NiTiHf) impedes their wider usage in many industrial applications. In this study, the quaternary alloying element of Pd has been added to NiTiHf alloys to improve and tailor their shape memory behavior,. NiTiHfPd alloys were systematically examined regarding the composition and heat treatments effects.

Effects of substituting Hf with Ti on the shape memory behavior of NiTHfPd alloys were investigated. There compositions ...