Mechanical Engineering Commons^™

Redesign Of Leg Assembly For Remote Walking Training Device To Improve Gait Kinematics, Jacob Anthony

Mechanical Engineering Theses

As modern medicine has improved, the average age of patients has increased. This has cause a growing number of patients to develop disabilities over time due to spinal cord injuries and stroke among other neurological ailments. This has led to an increased interest in developing robotic exoskeletons to help patients with neuromuscular rehabilitation. However, most exoskeletons do not accurately replicate the natural human gait kinematics due to a lack of degrees of freedom at the designed knee joint. In this thesis, the leg assembly for a robotic rehabilitation (RoboREHAB) device is redesigned to improve the gait kinematics and a reinforcement …

Redesign Of Robotic Walking Training Device To Involve Zero Gravity Capabilities And Daily Activities, Chad Ballard

Mechanical Engineering Theses

Many patients struggle with disabilities that hinder their ability to walk. This project aimed to create a leg assembly capable of variable gravity so that it could be combined with a Robotic Walking Training Device, and lead to better rehabilitation options for patients. This was accomplished by deriving equations of joint torque, creating circuit diagrams for Arduino systems, modeling leg assemblies in CAD, and finally combining it to create a working small-scale prototype. The result of the prototype testing showed accurate movement on each joint, especially the ankle and knee segments, to create virtual zero gravity. In addition to this, …

Residential Indoor Air Quality Study – Assessment And Mitigation, Giovanni Cerrato

Mechanical Engineering Theses

An increased awareness in residential indoor air quality (IAQ) has led to an increase in technologies that assist in improving IAQ. Two such technologies include Electro-static (ES) air cleaners and Photocatalytic Oxidizing (PCO) air cleaners. ES air cleaners remove particulate matter from indoor air, but are known to emit ozone, a contaminant, as a by-product. PCO air cleaners abate gaseous pollutants (i.e., Volatile Organic Compounds, VOCs); however, a lack of testing standards creates confusion about their effectiveness in improving IAQ in a real residential home. On the other hand, environmental variables such as temperature and humidity were found to affect …

Clean Energy & Sustainable Environment By Carbon Dioxide Mitigation Strategies, Md Fahim Shahriar

Mechanical Engineering Theses

Dissolution trapping is one of the most dominant mechanisms for secure storage of CO₂ injected in porous subsurface formations saturated with brine. This study uses a 2D visual Hele-Shaw cell to investigate and visualize the impact of CO₂ injection locations, reservoir dipping angle, permeability heterogeneity, and brine with different initial ionic concentrations on the density-driven convection during CO₂ dissolution (Chapter 2). Also, the role of complex heterogeneity, i.e., irregular permeability distribution in CO₂ dissolution, is investigated using a novel experimental approach to create medium permeability heterogeneity in Hele-Shaw cells (Chapter 3). We observed that the presence …

Investigation Of Magnetic Bistability For A Wider Bandwidth In Vibro-Impact Triboelectric Energy Harvesters, Qais Qaseem

Mechanical Engineering Theses

Mechanical energy from vibrations is widespread in the ambient environment. It may be harvested efficiently using triboelectric generators. Nevertheless, the harvesters' effectiveness is restricted because of the limited bandwidth. This thesis proposed a comprehensive theoretical and experimental investigation of a variable frequency energy harvester, which integrates a Vibro-impact triboelectric-based harvester and magnetic nonlinearity to increase the operation bandwidth and improve the efficiency of conventional triboelectric harvesters. A cantilever beam with a tip magnet is aligned with another fixed magnet at the same polarity to induce a nonlinear magnetic repulsive force. A triboelectric harvester is integrated into the system by utilizing …

Aeroacoustic Analyses For Noise Reduction Application, Mahmoud M. Abdalmola

Mechanical Engineering Theses

In this study, we examine the hypothesis that airflow noise can be reduced by adding metamaterials. The introduction of any obstacle will generate more disturbance in the airflow and therefore add noise. Hence an efficient metamaterial design is required, capable of reducing noise even at higher flow disturbance. In order to examine this hypothesis, we developed a platform to perform isogeometric aeroacoustic analyses to solve Navier stokes equations first. We obtained the velocity fields from fluid-structure analyses and utilized the light-hill analogy to calculate the noise generated as a result of airflow. Then the Helmholtz equation was solved to perform …

Experimental And Theoretical Investigation Of Vibro-Impact Triboelectric Energy Harvesters, Mostafa Hassan

Mechanical Engineering Theses

Improving the efficiency of energy harvesting, by investigating different techniques to increase the harvester bandwidth, as well as by exploring the influencing factors and adjusting them to optimal setups. Towards this, multiple Vibro-impact energy harvesters were proposed in this study. First, a Two-Degree of Freedom (2DOF) Vibro-impact Triboelectric Energy Harvester with a single and a double impact configuration is proposed. Multi-modality and piecewise linearity were combined to improve the harvesting bandwidth of triboelectric energy harvesters utilizing two resonant frequencies. The harvester structure consists of a primary cantilever beam attached to a secondary cantilever beam through a tip mass in the …

Efficient Energy Harvesting With Applications In Vibration And Implantable Biosensors, Mohammad Atmeh

Mechanical Engineering Theses

The world has stepped into the fourth industrial revolution in many ways such as using the internet of things (IoT) in various applications, and removing the rechargeable power sources seeking for batteryless systems. Since energy is widely abundant around us and it is going to waste, numerous of recent studies have been conducted to propose sustainable solutions to harvest the free ambient power from the surrounding and convert it into electricity. Heat energy, kinetic energy, and radio waves are examples of these potentially harvestable energy sources. Mechanical vibrations represent one of the most plentiful forms of kinetic energy that can …

Methodology To Compare Performance Of Residential Hvac Systems Operating In Cooling Mode, Manoj Bhandari

Mechanical Engineering Theses

Residential HVAC systems are selected and installed based on the goals of the customer. For spec homes, the most common types of systems are traditionally ducted with standard efficiency. However, for custom homes, the recent trend has included high-efficiency HVAC systems that are often accompanied by air-tight home envelopes with highly thermally resistant foam insulation in the walls. Several high-efficiency systems are available in the market with the performance of these systems varying between the different manufacturers and the types of systems. The systems available in the market can be compared and ranked based on their thermal performance and energy …

Hydrogen Peroxide Vapor Decontamination Of Polylactic Acid Fibers, Alexandra Craig

Mechanical Engineering Theses

Electrospun fibers have attracted attentions in topical drug delivery due to the ability to modulate drug release at high drug loading. While the pharmaceutical properties of these drug-eluting fibers were reported elsewhere, the compatibility of these fibers with hydrogen peroxide vapor, an effective decontaminant, is not fully established. In this work, polylactic acid (PLA) microfibers loaded with acetylsalicylic acid (ASA) were electrospun to examine their compatibility with hydrogen peroxide vapor. Results suggested a strengthening effect of the PLA/ASA fibers due to intermolecular interactions of ASA with PLA, which modulated the in vitro drug release rates. After exposing PLA/ASA fibers to …

Simultaneous Thermal Zoning And Demand Control Ventilation, Jose Rodriguez

Mechanical Engineering Theses

Heating Ventilation and Air Conditioning (HVAC) systems include the equipment used to control the conditions and distribution of indoor air in any closed environment that requires certain variables, such as temperature, humidity, carbon dioxide (CO₂) concentration, etc. to be controlled to levels of human comfort and safety, and to levels that keep machines and other devices in special conditions to protect them or guarantee their best performance. In developed countries, HVAC energy consumption is usually between 25% and 42% of the total energy consumption. Thermal zooning and demand control ventilation have shown improvements in comfort and energy consumption savings. The …

Thermal Control Development Of A Proton Exchange Membrane Fuel Cell System, Ola Mohammed Taha Al-Shalash

Mechanical Engineering Theses

A fuel cell is an electrochemical energy conversion device that uses fuel to generate electricity. It basically converts the chemical energy of reactants directly into electricity without combustion. In a Proton Exchange Membrane Fuel Cell (PEMFC), the reactants, hydrogen and oxygen, are fed into the two electrodes, anode and cathode, respectively. A reaction takes place at each electrode and produces electricity, as well as water, and heat as the by-products. In order to maximize performance of a fuel cell, many factors can be considered for tuning and control. Temperature management is one of these factors.

A thermal-fluid model of a …

Effects Of Hard-To-Soft Segment Ratios On The Synthesis And Physico-Mechanical Properties Of Polyurethane Films, Aaron C. Wilson

Mechanical Engineering Theses

Blood-contacting cardiovascular stents often induce a secondary clotting event due to unrestricted enzymatic activities. The use of hemocompatible polyurethane coatings on these implantable devices is one of the most promising methods to reduce device rejection. In this study, four commercial polyurethane films of various thicknesses and compositions were evaluated for their anticoagulation properties. Results suggested that these films exhibited excellent thermal and physico-mechanical properties while capable of increasing contact time with blood plasma by over a thousand-fold as compared to a control surface. Due to the unknown structure and composition of these commercial films, polyurethane samples were synthesized from toluene …

Spaspace Humidity Control Through A Single Speed Versus A Variable Speed Hvac Solution, Koukouni P. Kone

Mechanical Engineering Theses

Conventional air conditioning systems in houses respond to thermal loads by means of controlling dry-bulb temperature through the thermostat. As part of the process of conditioning the air, dehumidification is also provided. However, as houses are becoming more efficient, supplemental dehumidification is often necessary in homes located in hot and humid climates to control relative humidity intentionally. This study compared the dehumidification performance of three residential air conditioning systems: a system with a variable speed mode (VSPD), a system with an enhanced dehumidification mode activated (Enhanced Dehum), and a system without enhanced dehumidification capabilities (Normal Cooling). The research facility was …

Acoustic Design Optimization With Isogeometric Analysis And Differential Evolution, Garrett W. Dodgen

Mechanical Engineering Theses

The objective of this study is to utilize shape optimization to enhance the performance of devices relying on acoustic wave propagation. Particularly, the shape of a horn speaker and an acoustic energy harvester were optimized to enhance their performance at targeted frequencies. High order Isogeometric Analysis (IGA) was performed to estimate the acoustic pressure with minimum geometry and pollution errors [1]. The analysis platform was then combined with Differential Evolution (DE) to optimize the geometry of the horn speaker and energy harvester at a given frequency. These cases effectively demonstrate two applications of Isogeomtric shape optimization for devices relying on …

Integrated Design Approach For Coronary Stents Using Flexinol Shape Memory Alloy, Matthew Lucci

Mechanical Engineering Theses

This research seeks to develop and verify a model for control of the shape memory alloy (SMA) Flexinol and apply such findings to practical application of the material as a platform for bare metal stenting technologies. Utilizing experimental data and material properties, a mathematical model of the thermoelectric contraction behavior of Flexinol wire samples was developed. This model accounted for variable resistance due to the shape memory effect of the Flexinol wire as it experiences a crystalline phase change. It also accounted for the change in the cross-sectional area of the wire as the wire experienced thermal expansion and contraction. …

Physicochemical Properties Of Blend Poly (Vinyl Alcohol) And Sodium Alginate Membranes For Potential Application In Wound Dressings, Martha Pieper

Mechanical Engineering Theses

Poly (vinyl alcohol) (PVA) and sodium alginate (SA) are water-soluble polymers with excellent biocompatibility suitable for biomedical applications in wound dressings. In this study, pure PVA, pure SA, and blends of PVA/SA membranes were solvent cast into films followed by crosslinking in CaCl₂, boric acid, and a mixture of CaCl₂/boric acid solutions for 5, 10, and 30 minutes. Initial feasibility studies showed a strong correlation of film thickness to the observed mechanical properties. Further studies in solvent casting of blend PVA/SA films, using various polymer concentrations, yielded better film appearance with minimal physical changes after crosslinking. …

Acute Angle Repositioning In Mobile C-Arm Using Image Processing And Deep Learning, Armin Yazdanshenas

Mechanical Engineering Theses

During surgery, medical practitioners rely on the mobile C-Arm medical x-ray system (C-Arm) and its fluoroscopic functions to not only perform the surgery but also validate the outcome. Currently, technicians reposition the C-Arm arbitrarily through estimation and guesswork. In cases when the positioning and repositioning of the C-Arm are critical for surgical assessment, uncertainties in the angular position of the C-Arm components hinder surgical performance. This thesis proposes an integrated approach to automatically reposition C-Arms during critically acute movements in orthopedic surgery. Robot vision and control with deep learning are used to determine the necessary angles of rotation for desired …

Development Of A Hybrid Residential Hvac System: An Experimental Study Of A Variable Refrigerant Flow System With Ducted And Ductless Elements, Andrew C. Hernandez Iii

Mechanical Engineering Theses

The introduction of variable refrigerant flow (VRF) expands the range of development potential for HVAC systems. The hybridization of traditional HVAC ducted systems and ductless VRF integrates both the advantages and disadvantages of each system type. Existing research does not focus on hybridization but on individual component evaluation that covers quantitatively expansive evaporator or multiple compressor configurations. The Trane Residential Heating and Cooling Research Lab at the University of Texas at Tyler was used as the research facility to experiment and validate a hybrid ducted-ductless HVAC system where a ducted attic air handler unit and three ductless evaporator units were …

System Integration Of C-Arm Robotic Prototype Using Motion Capture Guidance For Accurate Repositioning, Alireza Yazdanshenas

Mechanical Engineering Theses

One of the important surgical tools in spinal surgery is the C-Arm X-ray System. The C-Arm is a large “C” shaped and manually maneuvered arm that provides surgeons and X-ray technicians the ability to take quick quality X-rays during surgery. Because of its five degrees of freedom, the C-Arm can be manually maneuvered around the patient to provide many angles and perspectives, ensuring surgical success.

This system works fine for most surgical procedures but falls short when the C-Arm must be moved out of the way for complicated surgical procedures.

The aim of this thesis is to develop an accurate …

Digital Enhancement Of Analog Measurement Systems For Temperature Compensation Of Strain Gages, Islombek Karimov

Electrical Engineering Theses

Generally known temperature compensation techniques for strain gages (like the use of a dummy gage or the implementation of half- and full-bridge configurations) are not applicable to all strain-measurement situations and cannot fully compensate for all sources of error. Digital Enhancement of Analog Measurement Systems presents a universal method of corrections for these effects in which temperature is measured independently of other variables and ex post facto corrections are computed and applied to digitized readings of the analog measurement system.

A single, linear-pattern strain gage, self-temperature-compensated for steel 1018, has been utilized in a quarter-bridge to measure tensile strain in …

Energy Models Of The Txaire Houses, Tajudeen Amadu Annafi

Mechanical Engineering Theses

Model calibration is important as its functions improve building models. A calibrated model of the TxAIRE Houses #1 and #2 have been developed using the OpenStudio software. The model was developed and calibrated with data of the year 2014 but can be used predict electricity consumption of any year.

An actual meteorological year (AMY) weather file was also created for the houses which was used for calibration. The data used to develop this weather file were measured on-site which improved the accuracy of the model. It was found that an error difference of -1.0 % and -4.2 % occurred between …

Measured And Predicted Performance Of A Photovoltaic Grid-Connected System In A Humid Subtropical Climate, Racquel Lovelace

Mechanical Engineering Theses

Solar energy is an alternative energy source that has the potential to provide energy for the very increasing global population. Photovoltaic modules are the means by which solar energy is collected. Photovoltaic modules convert sunlight into direct-current (DC) electricity which can then be converted to alternating current (AC) electricity and used in regular household systems. This research aimed to determine the measured and predicted performance of a photovoltaic grid-connected system in a humid subtropical climate. Simulation and numerical models were used to determine the predicted performance of the system to be compared to the recorded data from the system. In …

Artificial Intelligent Metallurgical Grain Detection, Adarsh Kesireddy

Mechanical Engineering Theses

In recent years, image processing has been applied to metallurgy but its applications were mainly confined to iron. This research instead focuses on recognizing phases present in steel. Phase recognition is very important because it aids in specifying the properties of steel specimens. This research is concentrated on recognizing Pearlite, Ferrite, Martensite and Cementite present in steel. A neural network was used to recognize these four phases. For a neural network to recognize any object it requires input values called features. This research introduces a combination of features which were not used before: texture based features of entropy, energy, contrast, …

A Characterization Of The Knee Moment Using The Niagara Foot, Kerron James

Mechanical Engineering Theses

A variety of low cost prosthetic feet exist, but sufficient data on these kinds of feet is limited. This study evaluated the effects of the Niagara Foot™ on an amputee performing walking tasks. Specifically, the study determined the effects of this foot on the amputee's residual knee compared to the amputees current prosthetic foot. An active transtibial amputee was used to perform walking tasks across a force plate to collect ground reaction forces of the amputee while wearing the Niagara Foot and the Ottobock® 1C31+ Trias. Motion capture was used to record the amputee's movements in the room. The data …