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Articles 1 - 30 of 34
Full-Text Articles in Engineering
High Fidelity Computational Modeling And Analysis Of Voice Production, Weili Jiang
High Fidelity Computational Modeling And Analysis Of Voice Production, Weili Jiang
Electronic Theses and Dissertations
This research aims to improve the fundamental understanding of the multiphysics nature of voice production, particularly, the dynamic couplings among glottal flow, vocal fold vibration and airway acoustics through high-fidelity computational modeling and simulations. Built upon in-house numerical solvers, including an immersed-boundary-method based incompressible flow solver, a finite element method based solid mechanics solver and a hydrodynamic/aerodynamic splitting method based acoustics solver, a fully coupled, continuum mechanics based fluid-structure-acoustics interaction model was developed to simulate the flow-induced vocal fold vibrations and sound production in birds and mammals. Extensive validations of the model were conducted by comparing to excised syringeal and …
Modeling Of Non-Newtonian Fluid Flow In A Porous Medium, Hamza Azzam
Modeling Of Non-Newtonian Fluid Flow In A Porous Medium, Hamza Azzam
Electronic Theses and Dissertations
Flows of Newtonian and non-Newtonian fluids in porous media are of considerable interest in several diverse areas, including petroleum engineering, chemical engineering, and composite materials manufacturing. In the first part of this thesis, one-dimensional linear and radial isothermal infiltration models for a non-Newtonian fluid flow in a porous solid preform are presented. The objective is to investigate the effects of the flow behavior index, preform porosity and the inlet boundary condition (which is either a known applied pressure or a fluid flux factor) on the infiltration front, pore pressure distribution, and fluid content variation. In the second part of the …
Design And Fabrication Of A 3-Dimensional Capacitive-Based Force Sensor, Md Shafiqur Rahman
Design And Fabrication Of A 3-Dimensional Capacitive-Based Force Sensor, Md Shafiqur Rahman
Electronic Theses and Dissertations
The detection of abnormal gait patterns is imperative for early diagnoses and treatment of serious health issues such as loss of mobility and balance, risk of falls, cardiovascular disease, etc. Human gait analysis is the tool used to detect abnormal gait patterns. Gait analysis also can help to understand the cause of gait abnormalities and to make a treatment plan for individual patients. Ground reaction forces (GRFs) at the foot during walking or running are essential for kinetic analysis of the human gait. However, there are no wearable systems that can directly measure three-directional (3D) forces during daily walking. Currently, …
Modeling And Analysis For Unit Cell Size, Material Anisotropy And Material Imperfection Effects Of Cellular Structures Fabricated By Powder Bed Fusion Additive Manufacturing., Yan Wu
Electronic Theses and Dissertations
Cellular structures are networks of interconnected struts or walls with porosities and are widely found in many natural load-bearing structures such as plants and bones. Cellular structures offer unique functional characteristics such as high stiffness to weight ratio, tailorable heat transfer coefficient, and enhanced mechanical energy absorption, which makes them highly attractive in various engineering disciplines such as biomedical implants, electrodes, heat exchangers, and lightweight structures. There exists an abundance of literatures that have investigated various mechanical properties of various cellular structures such as Poisson’s ratio, elastic modulus, ultimate strength, yield strength, and failure characteristics. Based on the classic cellular …
Development Of A Pediatric Cardiac Assist Maglev Pump For Use With A Universal Driver System., Landon Heath Tompkins
Development Of A Pediatric Cardiac Assist Maglev Pump For Use With A Universal Driver System., Landon Heath Tompkins
Electronic Theses and Dissertations
Heart failure (HF) remains the leading cause of death, affecting 26 million adults worldwide and 6.5 million adults in the United States. Pediatric HF patients have been a historically underserved population with few options for mechanical circulatory support (MCS) therapy, a leading treatment as an alternative to heart transplantation. To address this clinical need, the Inspired Universal MagLev System is being developed; a low cost, universal magnetically levitated extracorporeal MCS system with interchangeable single-use pumps that will ultimately provide adult and pediatric patients ventricular and respiratory assist therapies. The Inspired Pediatric VAD is the first single-use pump application for this …
Wave Attenuation Capacity Of Suspended Aquaculture Structures With Sugar Kelp And Mussels, Longhuan Zhu
Wave Attenuation Capacity Of Suspended Aquaculture Structures With Sugar Kelp And Mussels, Longhuan Zhu
Electronic Theses and Dissertations
Large aquaculture systems may have the potential to damp wave energy for coastal protection. The performance of these systems are influenced by the dynamics of components such as flexible kelp blades and mussel droppers. In this thesis, the dynamics of kelp blades and mussel droppers were investigated with a consistent-mass cable model with focus on understanding the asymmetric motion of kelp blades. The results showed the asymmetric blade motion in symmetric waves is caused by the spatial asymmetry of the encountered wave orbital velocities due to blade displacements and the asymmetric action on the blade by vertical wave orbital velocities. …
Methods For Mass Data Acquisition Of Whiskey Webs., Adam D. Carrithers
Methods For Mass Data Acquisition Of Whiskey Webs., Adam D. Carrithers
Electronic Theses and Dissertations
Whiskey webs are a recently discovered phenomenon in which the monolayer collapse during evaporation of diluted American whiskey results in self-assembled, web-like structures. It was found that the pattern of weblike structures were unique between different American whiskey products. It is desirable to use these unique patterns as a “fingerprint” which can be used to identify whiskeys, their chemical constituents, and perhaps even counterfeits. In pursuit of identifying whiskey products based on their web pattern, it is necessary to have a large database of samples imaged for each product. The device discussed herein is the realization of an apparatus capable …
Dynamic Analysis And Fabrication Of A Bi-Stable Structure Designed For Mems Energy Harvesting Applications., Masoud Derakhshani
Dynamic Analysis And Fabrication Of A Bi-Stable Structure Designed For Mems Energy Harvesting Applications., Masoud Derakhshani
Electronic Theses and Dissertations
Thanks to the rapid growth in demand for power in remote locations, scientists’ attention has been drawn to vibration energy harvesting as an alternative to batteries. Over the past ten years, the energy harvesting community has focused on bistable structures as a means of broadening the working frequency range and, by extension, the effective efficiency of vibration-based power scavenging systems. In the current study, a new method is implemented to statically and dynamically analyze a bistable buckled, multi-component coupled structure designed specifically for low-frequency vibration energy harvesting systems in both macro and MEMS-scale sizes. Furthermore, several micro-fabrication steps using advanced …
An Investigation Of The Effect Of Contour Process Parameters On The Surface Roughness And Dimensionality Of Overhanging Features In 17-4 Stainless Steel., Katherine Schneidau
An Investigation Of The Effect Of Contour Process Parameters On The Surface Roughness And Dimensionality Of Overhanging Features In 17-4 Stainless Steel., Katherine Schneidau
Electronic Theses and Dissertations
The relationship between varying contour settings and part geometry provides insight into the attainable surface roughness and dimensional accuracy of parts fabricated in 17-4 stainless steel via selective laser melting (SLM). Varying the contour settings of laser power (W), scan speed (mm/s), and beam offset (mm) for unsupported inclined bars. The utilization of a coordinate measuring machine (CMM) and surface profilometer quantified the dimensional accuracy and average surface roughness (Ra) for upface, downface, and topface surfaces. Adjusting the laser power and scan speed had minimal affect to surface roughness compared to part geometry. Part dimensionality was affected by the …
Aqueous Redox Flow Batteries With Boron Doped Diamond As An Electrode., Alex M. Bates
Aqueous Redox Flow Batteries With Boron Doped Diamond As An Electrode., Alex M. Bates
Electronic Theses and Dissertations
As the interest and implementation of renewable energy accelerates, so does that of grid energy storage. It is widely believed that a cost-effective energy storage technology will bring about the proliferation of renewable energy. Redox flow battery (RFB) technology represents a promising solution to cost-effective grid energy storage. Compared to other technologies, RFBs have a long lifetime, high efficiency, are non-flammable, significantly reduce cost, and separately scale power and energy. The separation of power and energy enables increased energy capacity by simply adding electrolyte volume. Of the challenges facing RFB technology, one readily apparent is the cost of the active …
Investigation Of Infiltration Measurements Using Wind Induced Pressure Response On An Enclosure, Aaron R. French
Investigation Of Infiltration Measurements Using Wind Induced Pressure Response On An Enclosure, Aaron R. French
Electronic Theses and Dissertations
Air infiltration into a building is unintentional air leakage, resulting in heat losses or gains and the consequent energy usage to recondition the building to comfortable levels. Methods of evaluating air infiltration provide accurate measures of air exchange rate but must be done per building and take significant experimentation and data collection. This warrants investigation into ways to decrease the time to evaluate building infiltration to decrease the associated costs. For this reason, interior pressure response is the subject of investigation in the present work. Interior pressure of a building responds to a pressure rise on the building face when …
Experimental Evaluation Of Heat Leak And Convective Heat Transfer In A Household Freezer., Catherine E. Berghuis
Experimental Evaluation Of Heat Leak And Convective Heat Transfer In A Household Freezer., Catherine E. Berghuis
Electronic Theses and Dissertations
Heat leak into household refrigerated cabinets is a key driver affecting energy consumption and efficiency of the cooling system. Additionally, knowledge of heat transfer coefficients of internal surfaces is valuable in the development of cabinet and system level performance simulations. Several studies have examined heat leak of refrigeration units using heat flux sensors (HFS); however, no such studies have used heat flux measurements to derive convective heat transfer coefficients of the refrigerated unit walls. The goal of this study is to evaluate the use of HFS to quantify heat leak into a 490-liter freezer and determine the wall convective heat …
Experimental And Numerical Study Of Process Parameters Effects Towards Part Quality And Porosity During Powder Bed Additive Manufacturing Processes., Subin Shrestha
Electronic Theses and Dissertations
Powder bed additive manufacturing (PB-AM) process utilizes an electron beam or a laser as a heat source to melt the metallic powder particles. These processes have the capability of freeform fabrication, however certain defects such as porosity, high surface roughness, etc. would hinder its application. It is important to understand the effect of the process parameters and the underlying physical phenomena, which lead to the formation of such defects. In this regard, a three-dimensional (3D) thermo-fluid model is developed to study the effect of beam speed on the surface morphology during powder bed electron beam additive fabrication (PB-EBAF). Besides, the …
Development And Test Of High Temperature Surface Acoustic Wave Gas Sensors, Armando E. Ayes Moncada
Development And Test Of High Temperature Surface Acoustic Wave Gas Sensors, Armando E. Ayes Moncada
Electronic Theses and Dissertations
The demand for sensors in hostile environments, such as power plant environments, exhaust systems and high-temperature metallurgy environments, has risen over the past decades in a continuous attempt to increase process control, improve energy and process efficiency in production, reduce operational and maintenance costs, increase safety, and perform condition-based maintenance in equipment and structures operating in high-temperature, harsh-environment conditions. The increased reliability, improved performance, and development of new sensors and networks with a multitude of components, especially wireless networks, are the target for operation in harsh environments. Gas sensors, in particular hydrogen gas sensors, operating above 200°C are required in …
A Linear Actuator/Spring Steel-Driven Glove For Assisting Individuals With Activities Of Daily Living, Daniel Chizhik
A Linear Actuator/Spring Steel-Driven Glove For Assisting Individuals With Activities Of Daily Living, Daniel Chizhik
Electronic Theses and Dissertations
Over three million people in the U.S. suffer from forearm and hand disabilities. This can result from aging, neurological disorders (e.g., stroke), chronic disease (e.g., arthritis), and injuries. Injuries to hands comprise one-third of all work-related injuries worldwide. This can lead to difficulties with activities of daily living (ADL), where one needs to grasp, lift, and release objects in the household. There is a rise in demand for assistive orthoses and gloves that can allow many people to regain their grasping/releasing ability and, thereby, their independence. The main contribution of this thesis is developing an assistive glove with the actuating …
Impact Resistance Of Fiber-Reinforced Composites Using Computational Simulations, Maitham Alabbad
Impact Resistance Of Fiber-Reinforced Composites Using Computational Simulations, Maitham Alabbad
Electronic Theses and Dissertations
Composite materials are widely used in aerospace, automotive and wind power industries due to their high strength-to-weight and stiffness-to-weight ratios and their improved mechanical properties compared to metals. The damage resistance of composite materials due to low velocity impact depends on fiber breakage, matrix cracking and delamination between the interfaces. In this research, a numerical investigation of low velocity impact response of a multidirectional symmetric carbon-epoxy composite laminate is carried out and presented. Two different finite element models are developed for composite laminates made of non-crimp fabric to investigate their behavior under different levels of impact energy. In the first …
Impact Of Magnetocaloric Material Properties On Performance Of A Magnetocaloric Heat Pump., Michael G. Schroeder
Impact Of Magnetocaloric Material Properties On Performance Of A Magnetocaloric Heat Pump., Michael G. Schroeder
Electronic Theses and Dissertations
In the field of magnetocaloric heat pumps much research has been performed around machine design and theoretical machines, but little has been researched around practical problems such as variability in material properties. The present work defines a simulation tool that has been proven with experimental data. Magnetocaloric material cascades were statistically analyzed and parameterized, such that they could be recreated parametrically using a split Lorentz function with normally distributed parameters. Correlated curve-defining values with standard deviations were used as input into the simulation tool to determine the effect of variation on cooling heat pump performance for a household refrigerator application. …
Materials-Processing Relationships For Metal Fused Filament Fabrication Of Ti-6al-4v Alloy., Paramjot Singh
Materials-Processing Relationships For Metal Fused Filament Fabrication Of Ti-6al-4v Alloy., Paramjot Singh
Electronic Theses and Dissertations
Additive manufacturing (AM) is at the mainstream to cater the needs for rapid tooling and small-scale part production. The metal AM of complex geometries is widely accepted and promoted in the industry. While several metal AM technologies exist and are matured to a level where expectation in terms of design and properties are possible to realize. But the metal AM suffers from the heavy expense to acquire equipment, isotropic property challenges, and potential hazards to work with loose reactive metal powder. With this motivation, the dissertation aims to develop the fundamental aspects to print metal parts with bound Ti-6Al-4V powder …
Influences Of Material Extrusion Additive Manufacturing (Meam) Parameters And Additives On Polyvinylidene Fluoride (Pvdf) Properties., Niknam Momenzadeh
Influences Of Material Extrusion Additive Manufacturing (Meam) Parameters And Additives On Polyvinylidene Fluoride (Pvdf) Properties., Niknam Momenzadeh
Electronic Theses and Dissertations
Beyond the beneficial characteristics of smart polymers associated with all polymers such as flexibility and cost fabrication, smart materials exhibit multifunctional behaviors. The prospect of integrating structural and sensing/actuation capabilities into a single structure gives design engineers an ability to innovate highly novel, multi-functional creations. Polyvinylidene Fluoride (PVDF) is one of the widely used multi-functional materials which offers a variety of desirable material properties. It possesses exceptional chemical and UV resistance, biocompatibility, low processing temperature and affordable price making it a competitive choice for many commercial applications. In addition, among polymers, PVDF is simply the most dominant piezoelectric polymer. On …
Selective Laser Melting 17-4 Ph Stainless Steel And The Effect Of Varied Thermal Treatments On Fatigue Behavior., Sean Daniel Dobson
Selective Laser Melting 17-4 Ph Stainless Steel And The Effect Of Varied Thermal Treatments On Fatigue Behavior., Sean Daniel Dobson
Electronic Theses and Dissertations
Fatigue failure is the leading source of loss in industry. In order for new means of manufacturing to move towards mainstream use a complete understanding of material and mechanical behavior must be gained. This endeavor seeks to aide in that task by observing the fatigue behavior of selective laser melting (SLM) additive manufacturing (AM) specimens and the effect of differing thermal treatment conditions for an optimized AM process. Stainless steel 17-4 PH specimens were fabricated using SLM AM and thermally treated to three conditions: as-built, solutionized and hardened, and direct hardened. These specimens were characterized for material (powder quality, density, …
Energy Efficiency And Alternative Energy Generation In Existing Buildings On A College Campus, Sameer Keshavan
Energy Efficiency And Alternative Energy Generation In Existing Buildings On A College Campus, Sameer Keshavan
Electronic Theses and Dissertations
Universities and colleges are looking for ways to be sustainable and save energy costs on their campuses. In terms of raw dollars, “America’s colleges and universities spend almost $7 billion a year in energy and utilities”. Campus buildings consume more than 80% of the energy utilized by the universities and it is often used in the form of electricity for lighting, ventilation, air-conditioning, and natural gas for heating. By reducing energy use, it will translate into cost savings that could be utilized towards student programs, facility improvements, and other university initiatives. This can be achieved by energy conservation efforts and …
Particle Injection Simulation On Cold Spray Technology, Christopher A. Santini
Particle Injection Simulation On Cold Spray Technology, Christopher A. Santini
Electronic Theses and Dissertations
Computational Fluid Dynamics (CFD) is a useful tool when it comes to research in the fields of Aerodynamics, Turbomachinery, and is used in several other fields of research. CFD is an important tool in the engineering industry because it allows for understanding and evaluation of a new design, this can lead to advancements in developing a more efficient and effective design. This tool helps in the understanding of the flow phenomena and how it can interact with its surroundings. One of the main reasons in the use of CFD is to reduce the cost of testing a design by running …
Computational Modeling Of Shock Wave Propagation In A Layered Composites, Nicholas Ryan Scott
Computational Modeling Of Shock Wave Propagation In A Layered Composites, Nicholas Ryan Scott
Electronic Theses and Dissertations
Modeling and simulation of a metallic flyer plate impacting a woven glass-fiber reinforced plastic (GRP) plate at different velocities was performed using the ALE3D© finite element code. The one-dimensional strain-based shock wave propagation experimental data in terms of time history of GRP’s back surface material particle velocity, available in open literature [1], were utilized in the calibration of a continuum damage mechanics (CDM) model. The experimental data included D7 Tool Steel and 7075-T6 aluminum flyer plates and two different GRP thicknesses (6.8 mm or 13.6 mm) with varying impact velocities in the range of about 8.5 m/s to 418 m/s. …
Strain-Based Mechanical Failure Analysis Of Buried Steel Pipeline Subjected To Landslide Displacement Using Finite Element Method, Sean Goodluck Mamuzo Edeki
Strain-Based Mechanical Failure Analysis Of Buried Steel Pipeline Subjected To Landslide Displacement Using Finite Element Method, Sean Goodluck Mamuzo Edeki
Electronic Theses and Dissertations
Landslide displacement is one of the major threats to the structural integrity of buried oil and natural gas pipelines that are often located far from major markets with terrains prone to permanent ground deformations. These pipelines can experience large longitudinal strains and circumferential deformation resulting from the differential ground movements thereby potentially impacting pipeline safety by adversely affecting structural capacity and leak tight integrity. In order to proffer theoretical basis for the design, safety evaluation and maintenance of pipelines, the failure analysis and mechanical behavior of buried API X65 steel pipeline perpendicularly crossing landslide area was investigated with the Finite …
Ultrasonic-Based Condition Assessment Of Wooden Utility Poles, Yishi Lee
Ultrasonic-Based Condition Assessment Of Wooden Utility Poles, Yishi Lee
Electronic Theses and Dissertations
More than 300 million utility poles shoulder the utility grid in the United States. However, the ineffectiveness of the current inspection process causes roughly a third of utility poles removed from the service deemed suitable for reuse. Due to the utterly essential role of the power infrastructure, budget shrinkage, and the structural degradation of the modern distribution grid, this Ph.D. dissertation addresses the challenges by proposing a physics-based signal analysis method with a jointly developed ultrasonic UB1000 system c to enhance the objectivity in ultrasonic-based nondestructive evaluation (NDE). The proposed methodology has been deployed commercially in the field and featured …
The Effects And Analysis Of Implant Type And Surgical Approach In Total Hip Arthroplasty Dislocation Resistance, Brittany Marshall
The Effects And Analysis Of Implant Type And Surgical Approach In Total Hip Arthroplasty Dislocation Resistance, Brittany Marshall
Electronic Theses and Dissertations
Total hip arthroplasty (THA) is one of the most successful orthopaedic surgeries performed, in which the hip joint is reconstructed to decrease pain and to improve the functionality to the joint. Although these surgeries are very successful, there still remain areas for improvement, such as failures due to instability and dislocation of the implanted joint. The purpose of this thesis is to investigate the effect of surgical entrance approach on dislocation, the effect of implant type, and the effect of capsule repair and closure. The need to quantify the resistance to dislocation is important in understanding the effect that each …
Effects On Initial Fixation Of Cementless Tibial Trays In Total Knee Arthroplasty, Brooke Fritts Thompson
Effects On Initial Fixation Of Cementless Tibial Trays In Total Knee Arthroplasty, Brooke Fritts Thompson
Electronic Theses and Dissertations
Bone mineral density (BMD), among other factors, largely effect the initial stability of the cementless tibial tray component in a total knee replacement (TKR), where increased motion at the tray-bone interface hinders bony ingrowth. With a lack of bony ingrowth, the cementless implant will not experience long-term success. Understanding which factors influence initial stability yields insight into surgical technique considerations and help inform a surgeon’s implant choice. The objective of this study was to evaluate factors influencing the initial stability of cementless tibial trays using a 6-degree of freedom (6-DOF) robotic joint simulator, the AMTI VIVO, and combined loading scenarios …
Using Computational Fluid Dynamics To Accurately Model Agricultural Spray Nozzles, Zachary Chapman
Using Computational Fluid Dynamics To Accurately Model Agricultural Spray Nozzles, Zachary Chapman
Electronic Theses and Dissertations
Computational fluid dynamics (CFD) is a tool used by engineers in many industries to study fluid flow. A relatively new industry to adopt the use of CFD is the agricultural industry. The present work seeks to understand whether CFD can be used to accurately model spray nozzles. A spray nozzle commonly used in agricultural spraying was simulated. First, the impact of factors such as mesh size, mesh type, and physics models have on the solution were investigated. Next, a method to pulse the spray was determined. This was required to compare simulation results with experimental data. A user-defined function was …
A Series-Elastic Robot For Back-Pain Rehabilitation, Elhussein Shata
A Series-Elastic Robot For Back-Pain Rehabilitation, Elhussein Shata
Electronic Theses and Dissertations
Robotics research has been broadly expanding into various fields during the past decades. It is widely spread and best known for solving many technical necessities in different fields. With the rise of the industrial revolution, it upgraded many factories to use industrial robots to prevent the human operator from dangerous and hazardous tasks. The rapid development of application fields and their complexity have inspired researchers in the robotics community to find innovative solutions to meet the new desired requirements of the field. Currently, the creation of new needs outside the traditional industrial robots are demanding robots to attend to the …
Development Of Cellulose Acetate-Based Scaffold For Bone Tissue Engineering Applications, Ruhit Sinha
Development Of Cellulose Acetate-Based Scaffold For Bone Tissue Engineering Applications, Ruhit Sinha
Electronic Theses and Dissertations
Cellulose Acetate (CA) based biomaterials are being used as substrates for bone ingrowth applications due to their nontoxic and nonirritant nature coupled with optimum morphology and stiffness. Electrospinning with additives and/or post-treatment has emerged as a viable protocol to further improve mechanical properties of CA and expand its utility. Herein, we highlight the role of potassium chloride (KCl) in association with airdrying to enhance the elastic modulus and tensile strengths of CA fibers. Salt aggregation in between fibers is observed through Scanning Electron Microscopy (SEM), however, Fourier-transform infrared (FTIR) analysis signifies the interactions between K+ ions and acetyl groups. The …