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Full-Text Articles in Mechanical Engineering

Analysis Of Printed Electronic Adhesion, Electrical, Mechanical, And Thermal Performance For Resilient Hybrid Electronics, Clayton Neff Nov 2018

Analysis Of Printed Electronic Adhesion, Electrical, Mechanical, And Thermal Performance For Resilient Hybrid Electronics, Clayton Neff

Graduate Theses and Dissertations

Today’s state of the art additive manufacturing (AM) systems have the ability to fabricate multi-material devices with novel capabilities that were previously constrained by traditional manufacturing. AM machines fuse or deposit material in an additive fashion only where necessary, thus unlocking advantages of mass customization, no part-specific tooling, near arbitrary geometric complexity, and reduced lead times and cost. The combination of conductive ink micro-dispensing AM process with hybrid manufacturing processes including: laser machining, CNC machining, and pick & place enables the fabrication of printed electronics. Printed electronics exploit the integration of AM with hybrid processes and allow embedded and/or ...


Acoustic Source Localization With A Vtol Suav Deployable Module, Kory Olney Nov 2018

Acoustic Source Localization With A Vtol Suav Deployable Module, Kory Olney

Graduate Theses and Dissertations

A real time acoustic direction-finding module has been developed to estimate the ele- vation and azimuth of an impulsive event while function aboard a small unmanned air- craft vehicle. The generalized cross-correlation with phase transform method was used to estimate time differences of arrival in an 8 channel microphone array. A linear least squares approach was used to calculate an estimate for the direction of arrival. In order to accomplish this task, a vertical takeoff and landing small unmanned aircraft system was assembled to host the direction finding module. The module itself is made up of an eight-channel synchronous analog-to-digital ...


Synthesis And Characterization Of Alpha-Hematite Nanomaterials For Water-Splitting Applications, Hussein Alrobei Jul 2018

Synthesis And Characterization Of Alpha-Hematite Nanomaterials For Water-Splitting Applications, Hussein Alrobei

Graduate Theses and Dissertations

The recent momentum in energy research has simplified converting solar to electrical energy through photoelectrochemical (PEC) cells. There are numerous benefits to these PEC cells, such as the inexpensive fabrication of thin film, reduction in absorption loss (due to transparent electrolyte), and a substantial increase in the energy conversion efficiency. Alpha-hematite ([U+F061]-Fe2O3) has received considerable attention as a photoanode for water-splitting applications in photoelectrochemical (PEC) devices. The alpha-hematite ([U+F061]-Fe2O3) nanomaterial is attractive due to its bandgap of 2.1eV allowing it to absorb visible light. Other benefits of [U+F061]-Fe2O3 include low cost, chemical stability ...


Toward Verifiable Adaptive Control Systems: High-Performance And Robust Architectures, Benjamin Charles Gruenwald Jun 2018

Toward Verifiable Adaptive Control Systems: High-Performance And Robust Architectures, Benjamin Charles Gruenwald

Graduate Theses and Dissertations

In this dissertation, new model reference adaptive control architectures are presented with stability, performance, and robustness considerations, to address challenges related to the verification of adaptive control systems.

The challenges associated with the transient performance of adaptive control systems is first addressed using two new approaches that improve the transient performance. Specifically, the first approach is predicated on a novel controller architecture, which involves added terms in the update law entitled artificial basis functions. These terms are constructed through a gradient optimization procedure to minimize the system error between an uncertain dynamical system and a given reference model during the ...


A Quantitative Analysis Of Shape Characteristics Of Marine Snow Particles With Interactive Visualization: Validation Of Assumptions In Coagulation Models, Palak P. Dave Jun 2018

A Quantitative Analysis Of Shape Characteristics Of Marine Snow Particles With Interactive Visualization: Validation Of Assumptions In Coagulation Models, Palak P. Dave

Graduate Theses and Dissertations

The Deepwater Horizon oil spill that started on April 20, 2010, in the Gulf of Mexico was the largest marine oil spill in the history of the petroleum industry. There was an unexpected and prolonged sedimentation event of oil-associated marine snow to the seafloor due to the oil spill. The sedimentation event occurred because of the coagulation process among oil associated marine particles. Marine scientists are developing models for the coagulation process of marine particles and oil, in order to estimate the amount of oil that may reach the seafloor along with marine particles. These models, used certain assumptions regarding ...


Simulation Of Radiation Flux From Thermal Fluid In Origami Tubes, Robert R. Bebeau Jun 2018

Simulation Of Radiation Flux From Thermal Fluid In Origami Tubes, Robert R. Bebeau

Graduate Theses and Dissertations

Spacecraft in orbit experience temperature swings close to 240 K as the craft passes from the shadow of the Earth into direct sunlight. To regulate the craft’s internal energy, large radiators eject unwanted energy into space using radiation transfer. The amount of radiation emitted is directly related to the topology of the radiator design. Deformable structures such as those made with origami tessellation patterns offer a mechanism to control the quantity of energy being emitted by varying the radiator shape. Three such patterns, the Waterbomb, Huffman Waterbomb, and Huffman Stars-Triangles, can be folded into tubes. Origami tubes offer greater ...


Design And Testing Of A Passive Prosthetic Ankle Foot Optimized To Mimic An Able-Bodied Gait, Millicent Schlafly Jun 2018

Design And Testing Of A Passive Prosthetic Ankle Foot Optimized To Mimic An Able-Bodied Gait, Millicent Schlafly

Graduate Theses and Dissertations

Currently there are nearly 2 million people living with limb loss in the United States [1]. Many of these individuals are either transtibial (below knee) or transfemoral (above knee) amputees and require an ankle-foot prosthesis for basic mobility. While there are an abundance of options available for individuals who require an ankle-foot prosthesis, these options fail to mimic an intact ankle when it comes to key evaluation criteria such as range of motion, push-off force, and roll over shape. The roll over shape is created by plotting the center of pressure during a step in a shank-based coordinate system. To ...


Efficient Adjacency Queries And Dynamic Refinement For Meshfree Methods With Applications To Explicit Fracture Modeling, James Olliff Jun 2018

Efficient Adjacency Queries And Dynamic Refinement For Meshfree Methods With Applications To Explicit Fracture Modeling, James Olliff

Graduate Theses and Dissertations

Meshfree methods provide a more practical approach to solving problems involving large deformation and modeling fracture compared to the Finite Element Method (FEM). However meshfree methods are more computationally intensive compared to FEM, which can limit their practicality in engineering. Meshfree methods also lack a clear boundary definition, restricting available visualization techniques. Determining particle locations and attributes such that a consistent approximation is ensured can be challenging in meshfree methods, especially when employing h-refinement. The primary objective of this work is to address the limitations associated with computational efficiency, meshfree domain discretization, and h-refinement, including both placement of particles as ...


Simulation Of Turbulent Air Jet Impingement For Commercial Cooking Applications, Shantanu S. Shevade Jun 2018

Simulation Of Turbulent Air Jet Impingement For Commercial Cooking Applications, Shantanu S. Shevade

Graduate Theses and Dissertations

The research work in this dissertation focuses on turbulent air jet heat transfer for commercial cooking applications.

As a part of this study, convective heat transfer coefficient and its interdependency with various key parameters is analyzed for single nozzle turbulent jet impingement. Air is used as the working fluid impinging on the flat surface. A thorough investigation of velocity and temperature distributions is performed by varying nozzle velocity and height over diameter ratio (H/D). Nusselt number and Turbulent Energy are presented for the impingement surface. It was found that for H/D ratios ranging between 6 and 8, nozzle ...


Defect Detection In Additive Manufacturing Utilizing Long Pulse Thermography, James Pierce Mar 2018

Defect Detection In Additive Manufacturing Utilizing Long Pulse Thermography, James Pierce

Graduate Theses and Dissertations

Additive Manufacturing (AM), over the years, has seen a tremendous amount of research for improving the manufacturability of materials into final products. The main advantages of additive manufacturing are the minimizing of waste material as it is an additive process. As well as the ability to create custom low-volume products without the need for creation of expensive tooling or programming before manufacturing begins. Because of these advantages, however, AM is susceptible to unique challenges in the quality side of manufacturing. These challenges include minimizing and detecting defects during the build. The focus of this research looks at the capability of ...


Design And Testing Of A Linear Compliant Mechanism With Adjustable Force Output, William Niemeier Mar 2018

Design And Testing Of A Linear Compliant Mechanism With Adjustable Force Output, William Niemeier

Graduate Theses and Dissertations

This thesis presents a novel compliant mechanism with adjustable force output. The force comes from the bending of a rectangular cross section beam within the mechanism. By rotating this beam with a stepper motor, the force output of the mechanism changes. A model was made to simulate this mechanism, and a prototype was made based off of this data. A test apparatus was constructed around this mechanism, and a series of tests were performed. These tests adjusted parameters such as beam rotation speed and weight in order to characterize the system. Adjustments were made based on this information and the ...


Analysis Of Ni And Fe-Based Alloys For Turbine Seal Ring Applications, Dawei She Mar 2018

Analysis Of Ni And Fe-Based Alloys For Turbine Seal Ring Applications, Dawei She

Graduate Theses and Dissertations

Metal sealing rings have been used widely in compressors, turbines and hydraulic devices. Such rings can extend out due to elasticity, and keep close contact with the valve wall, resulting in the formation of a functional seal under pressure. In this project, the failure of metal sealing rings is considered. Sealing component failure due to stress relaxation can threaten the safety of the whole steam turbine. The object of this study was to examine the stress relaxation response and corresponding changes in microstructure of metal sealing rings used in nuclear steam turbine under high temperature and applied stress. The two ...


Developing Motion Platform Dynamics For Studying Biomechanical Responses During Exercise For Human Spaceflight Applications, Kaitlin Lostroscio Mar 2018

Developing Motion Platform Dynamics For Studying Biomechanical Responses During Exercise For Human Spaceflight Applications, Kaitlin Lostroscio

Graduate Theses and Dissertations

In future human spaceflight missions, with prolonged exposure to microgravity, resistive and aerobic exercises will be countermeasures for bone loss, muscle loss, and decreased aerobic capacity. Two of the exercises of interest are squats and rowing. The cyclic forces produced during these exercises are at relatively low frequencies which are likely to excite structural resonances of space vehicles. Vibration Isolation Systems (VIS) are being designed to be paired with future exploration exercise devices in order to prevent these cyclic exercise forces from impacting the space vehicle. The VIS may be configured such that a platform supports the human and exercise ...


Effectiveness Of Biocide Substitution And Management Plan Implementation For The Control Of, Adelmarie Bones Mar 2018

Effectiveness Of Biocide Substitution And Management Plan Implementation For The Control Of, Adelmarie Bones

Graduate Theses and Dissertations

After the notorious outbreak and discovery of Legionella bacteria in 1976, the waterborne pathogen was added to the list of disease-causing agents associated with the built environment. Legionella pneumophila was discovered when it was identified as the agent that caused 34 deaths and an outbreak of pneumonia-like symptoms in several attendees of the 1976 American Legion Convention held in Philadelphia (OSHA, 2017).

Recently published data from the year 2015 reported more than 6,000 Legionnaires’ cases identified in the United States (CDC, 2016). This is a concerning number given that one in every ten infected persons will die of the ...


Dns And Les Of Scalar Transfer Across An Air-Water Interface During Inception And Growth Of Langmuir Circulation, Amine Hafsi Nov 2017

Dns And Les Of Scalar Transfer Across An Air-Water Interface During Inception And Growth Of Langmuir Circulation, Amine Hafsi

Graduate Theses and Dissertations

Direct numerical simulations (DNS) of an initially quiescent coupled air-water interface driven by an air flow with free stream speed of 5 m/s have been conducted. The DNS solves a scalar advection-diffusion equation for dissolved gas (or scalar) concentration in order to determine the impact of the water-side turbulence on scalar (mass) transfer from the air side to the water side and subsequent vertical transport in the water column. Two simulations are compared: one with a freely deforming interface and a second one with a flat interface. In the first simulation, the deforming interface evolves in the form of ...


Experimental Study Of High-Temperature Range Latent Heat Thermal Energy Storage, Chatura Wickramaratne Nov 2017

Experimental Study Of High-Temperature Range Latent Heat Thermal Energy Storage, Chatura Wickramaratne

Graduate Theses and Dissertations

Among all thermal energy storage (TES) systems, latent heat thermal energy storage (LHTES) attracts high interest due to its high energy density and high exergetic efficiency. Due to the high enthalpy of fusion and low cost, inorganic salts are becoming popular as phase change materials and are used as the storage media in LHTES systems. The main drawbacks for the inorganic salts are their low thermal conductivity and high reactivity above 500°C. Therefore, designing a cost-effective containment at these conditions with longevity is a challenge. Macro-encapsulation of the PCM is one way to solve both the PCM containment issue ...


Development Mems Acoustic Emission Sensors, Adrian Enrique Avila Gomez Nov 2017

Development Mems Acoustic Emission Sensors, Adrian Enrique Avila Gomez

Graduate Theses and Dissertations

The purpose of this research is to develop MEMS based acoustic emission sensors for structural health monitoring. Acoustic emission (AE) is a well-established nondestructive testing technique that is typically used to monitor for fatigue cracks in structures, leaks in pressurized systems, damages in composite materials or impacts. This technology can offer a precise evaluation of structural conditions and allow identification of imminent failures or minor failures that can be addressed by planned maintenances routines. AE causes a burst of ultrasonic energy that is measured as high frequency surface vibrations (30 kHz to 1 MHz) generated by transient elastic waves that ...


Synthesis, Characterization, And Application Of Molybdenum Oxide Nanomaterials, Michael S. Mccrory Nov 2017

Synthesis, Characterization, And Application Of Molybdenum Oxide Nanomaterials, Michael S. Mccrory

Graduate Theses and Dissertations

Nanostructured molybdenum trioxide (MoO3) was synthesized and used as a precursor in a comparative study, along with commercial MoO3, to synthesize molybdenum dioxide (MoO2) nanoparticles. Scanning electron microscope (SEM) images revealed the particles to be approximately 30-50 nm in diameter. X-ray diffraction (XRD) confirmed MoO3 was fully reduced to MoO2 in all cases. Time dependent experiments showed that within two hours no traces of MoO3 are present. All of the experiments showed the materials were excellent absorbent materials, as well as photocatalysts. Both MoO2 materials performed almost exactly the same, with both samples ...


Rehabilitating Asymmetric Gait Using Asymmetry, Tyagi Ramakrishnan Nov 2017

Rehabilitating Asymmetric Gait Using Asymmetry, Tyagi Ramakrishnan

Graduate Theses and Dissertations

Human gait is a complex process that involves the coordination of the central nervous and muscular systems. A disruption to the either system results in the impairment of a person’s ability to walk. Impairments can be caused by neurological disorders such as stroke and physical conditions like amputation. There is not a standardized method to quantitatively assess the gait asymmetry of affected subjects. The purpose of this research is to understand the fundamental aspects of asymmetrical effects on the human body and improve rehabilitation techniques and devices. This research takes an interdisciplinary approach to address the limitations with current ...


Large Area Sintering Test Platform Design And Preliminary Study On Cross Sectional Resolution, Christopher J. Gardiner Nov 2017

Large Area Sintering Test Platform Design And Preliminary Study On Cross Sectional Resolution, Christopher J. Gardiner

Graduate Theses and Dissertations

Additive manufacturing involves the layer-wise patterned addition of material to create 3D parts, allowing for parts with complex geometries that traditional subtractive manufacturing processes cannot create, while offering good value for low run production parts by eliminating the cost of tooling. Large Area Sintering is a form of powder based additive manufacturing where entire layer cross sections are heated and fused in a single continuous exposure process. This layer by layer powder sintering process is similar to selective laser sintering, but by heating the cross section at a slower and controllable rate there is an opportunity to achieve tighter control ...


Novel Transducer Calibration And Simulation Verification Of Polydimethylsiloxane (Pdms) Channels On Acoustic Microfluidic Devices, Scott T. Padilla Jul 2017

Novel Transducer Calibration And Simulation Verification Of Polydimethylsiloxane (Pdms) Channels On Acoustic Microfluidic Devices, Scott T. Padilla

Graduate Theses and Dissertations

The work and results presented in this dissertation concern two complimentary studies that are rooted in surface acoustic waves and transducer study.

Surface acoustic wave devices are utilized in a variety of fields that span biomedical applications to radio wave transmitters and receivers. Of interest in this dissertation is the study of surface acoustic wave interaction with polydimethylsiloxane. This material, commonly known as PDMS, is widely used in the microfluidic field applications in order to create channels for fluid flow on the surface of a piezoelectric substrate. The size, and type of PDMS that is created and ultimately etched on ...


Force Compensation And Recreation Accuracy In Humans, Benjamin Rigsby Jun 2017

Force Compensation And Recreation Accuracy In Humans, Benjamin Rigsby

Graduate Theses and Dissertations

As industry becomes increasingly reliant on robotic assistance and human-computer interfaces, the demand to understand the human sensorimotor system’s characteristics intensifies. Although this field of research has been going on for over a century, new technologies push the limits of the human motor system and our knowledge of it. With new technologies come new abilities, and, in the area of medical care and rehabilitation, the need to expand our knowledge of the sensorimotor system comes from both the patient and physician.

Two studies relating to human force interaction are presented in this thesis. The first study

focuses on humans ...


Enhanced Visible Light Photocatalytic Remediation Of Organics In Water Using Zinc Oxide And Titanium Oxide Nanostructures, Srikanth Gunti Jun 2017

Enhanced Visible Light Photocatalytic Remediation Of Organics In Water Using Zinc Oxide And Titanium Oxide Nanostructures, Srikanth Gunti

Graduate Theses and Dissertations

The techniques mostly used to decontaminate air as well as water pollutants have drawbacks in terms of higher costs, require secondary treatment, and some methods are very slow. So, emphasis has been given to water though the use of photocatalysts, which break organic pollutants to water and carbon dioxide and leave no trace of by-products at the end. Photocatalytic remediation aligns with the waste and wastewater industries’ zero waste schemes with lower cost, eco-friendly and sustainable treatment technology. The commonly used photocatalysts such as titanium oxide (TiO2), zinc oxide (ZnO), tungsten oxide (WO3) have band gap of nearly ...


Experimental Evaluation Of Cooling Effectiveness And Water Conservation In A Poultry House Using Flow Blurring® Atomizers, Rafael M. Rodriguez Apr 2017

Experimental Evaluation Of Cooling Effectiveness And Water Conservation In A Poultry House Using Flow Blurring® Atomizers, Rafael M. Rodriguez

Graduate Theses and Dissertations

Increases in population as well as economic improvements in developing countries are generating a larger demand for animal protein products. Current animal growth processes inherently, require the use of water in many forms throughout the growth cycle. Water is the most important natural resource on earth to sustain life, and in many developing countries is a scarce resource that must be used wisely. Studies have revealed that poultry growth can take place with less water consumption, when compared with other sources of animal protein (e.g., cattle, pork). In this research, an evaporative Flow Blurring® cooling system was considered as ...


Effects Of Microstructure And Alloy Concentration On The Corrosion And Tribocorrosion Resistance Of Al-Mn And We43 Mg Alloys, Hesham Y. Saleh Mraied Mar 2017

Effects Of Microstructure And Alloy Concentration On The Corrosion And Tribocorrosion Resistance Of Al-Mn And We43 Mg Alloys, Hesham Y. Saleh Mraied

Graduate Theses and Dissertations

The design of new engineering materials resistant to both wear damage and corrosion degradation becomes increasingly demanding in complex service conditions. Unfortunately, there is typically a tradeoff between wear and corrosion resistance, even for important passive metals such as Al alloys. This is because the presence of precipitates hardens the material but at the same time lead to unfavorable galvanic coupling between the precipitates and the matrix, resulting in accelerated corrosion. This work showed that Al (or Mg) supersaturated solid solution formed using non-equilibrium methods exhibited enhanced corrosion resistance without compromising strength. For Al, alloying with Mn up to ~ 20 ...


Media Velocity Considerations In Pleated Air Filtration, Frederik Carl Schousboe Mar 2017

Media Velocity Considerations In Pleated Air Filtration, Frederik Carl Schousboe

Graduate Theses and Dissertations

Asset protection in the form of fluid filtration makes up an ever-increasing part of the civilized and industrialized world. Fluid filtration applications in the conditioned environment and life sciences are affording the world’s population a chance to better realize their potential, while industrial applications help ensure that high demand processes can be carried out safely, reliably, and effectively.

In the present work, a tool has been developed, using the computational fluid dynamics package FLUENT, to allow the designer to better predict the magnitude of geometric imperfections within a given pleat configuration.

Pleated rectangular filters, intended to improve the quality ...


Orthoplanar Spring Based Compliant Force/Torque Sensor For Robot Force Control, Jerry West Mar 2017

Orthoplanar Spring Based Compliant Force/Torque Sensor For Robot Force Control, Jerry West

Graduate Theses and Dissertations

A compliant force/torque sensor for robot force control has been developed. This thesis presents methods of designing, testing, and implementing the sensor on a robotic system. The sensor uses an orthoplanar spring equipped with Hall-effect sensors to measure one component of force and two moment components. Its unique design allows for simple and cost effective manufacturing, high reliability, and compactness. The device may be used in applications where a robot must control contact forces with its environment, such as in surface cleaning tasks, manipulating doors, and removing threaded fasteners. The compliant design of the sensor improves force control performance ...


Simulation Of Hemiparetic Function Using A Knee Orthosis With Variable Impedance And A Proprioception Interference Apparatus, Christina-Anne Kathleen Lahiff Mar 2017

Simulation Of Hemiparetic Function Using A Knee Orthosis With Variable Impedance And A Proprioception Interference Apparatus, Christina-Anne Kathleen Lahiff

Graduate Theses and Dissertations

Individuals with stroke have neuromuscular weakness or paralysis on one side of the body caused by some muscles disengaging and overexciting other muscles. Hyperextension of the knee joint and complete lack of plantar flexion of the ankle joint are common symptoms of stroke. This thesis encompasses the simulation of hemiparetic function using both a knee orthosis with variable impedance, specifically in terms of stiffness and damping, and the Proprioception Interference Apparatus.

The section regarding the knee orthosis with variable impedance focuses on the creation and implementation of a small, lightweight, and adjustable orthotic device to be positioned around the knee ...


A Framework For Studying Meshfree Geometry And A Method For Explicit Boundary Determination, Joseph Bradley Alford Nov 2016

A Framework For Studying Meshfree Geometry And A Method For Explicit Boundary Determination, Joseph Bradley Alford

Graduate Theses and Dissertations

Patient-specific biomechanical analysis is an important tool used to understand the complex processes that occur in the body due to physical stimulation. Patient-specific models are generated by processing medical images; once an object from the image is identified via segmentation, a point cloud representation of the object is extracted. Generating an analysis suitable representation from the point cloud has traditionally required generating a finite element mesh, which often requires a well defined surface to accomplish. Point clouds lack a well defined geometry, meaning that the surface definition is incomplete at best. Point clouds that have been generated from images have ...


Experimental And Computational Study On Fracture Mechanics Of Multilayered Structures, Hai Thanh Tran Nov 2016

Experimental And Computational Study On Fracture Mechanics Of Multilayered Structures, Hai Thanh Tran

Graduate Theses and Dissertations

Many devices in electronics are in the form of multilayered structures. These structures can fail catastrophically if they contain defects or cracks. Enhancing their fracture properties is therefore critical to improve the reliability of the systems. The interface-dominated fracture mechanics of multilayered structure was studied using experiments and finite element (FE) modeling by considering two examples: thin films on polymer substrates in flexible electronics and Cu leadframe/epoxy molding compound (EMC) in micro-electronics packaging.

In the first example, aluminum-manganese (Al-Mn) thin films with Mn concentration up to 20.5 at.% were deposited on polyimide (PI) substrates. A variety of phases ...