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 …

Dynamic Thermal Model Development Of Direct Methanol Fuel Cell, Mohammad Biswas, Tabbi Wilberforce

Mechanical Engineering Faculty Publications and Presentations

Direct methanol fuel cell (DMFC) is fueled with liquid methanol coupled with air to produce power at reasonably lower operational conditions while resulting in by-products of carbon dioxide and water, which is more environmentally friendly. Due to the complexity associated with the performance of direct methanol fuel cell, the application of artificial neural network (ANN) can significantly predict the characteristic performance of the cells. Nevertheless, limited studies have delved into the exploration of artificial neural network in the prediction of the transient characteristics of direct methanol fuel cells. The current study however presents a detailed investigation into the prediction of …

Static And Dynamic Analysis Of A Bistable Frequency Up-Converter Piezoelectric Energy Harvester, Mohammad Atmeh, Alwathiqbellah Ibrahim, Abdallah Ramini

Mechanical Engineering Faculty Publications and Presentations

Using energy harvesting to convert ambient vibrations efficiently to electrical energy has become a worthy concept in recent years. Nevertheless, the low frequencies of the ambient vibrations cannot be effectively converted to power using traditional harvesters. Therefore, a frequency up-conversion harvester is presented to convert the low-frequency vibrations to high-frequency vibrations utilizing magnetic coupling. The presented harvester consists of a low-frequency beam (LFB) and a high-frequency beam (HFB) with identical tip magnets facing each other at the same polarity. The HFB, fully covered by a piezoelectric strip, is utilized for voltage generation. The dynamic behavior of the system and the …

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 …

A Study Into Proton Exchange Membrane Fuel Cell Power And Voltage Prediction Using Artificial Neural Network, Tabbi Wilberforce, Mohammad Biswas

Mechanical Engineering Faculty Publications and Presentations

Polymer Electrolyte Membrane fuel cell (PEMFC) uses hydrogen as fuel to generate electricity and by-product water at relatively low operating temperatures, which is environmentally friendly. Since PEMFC performance characteristics are inherently nonlinear and related, predicting the best performance for the different operating conditions is essential to improve the system's efficiency. Thus, modeling using artificial neural networks (ANN) to predict its performance can significantly improve the capabilities of handling multi-variable nonlinear performance of the PEMFC. This paper predicts the electrical performance of a PEMFC stack under various operating conditions. The four input terms for the 5 W PEMFC include anode and …

Dehumidification Performance Of A Variable Speed Heat Pump And A Single Speed Heat Pump With And Without Dehumidification Capabilities In A Warm And Humid Climate, Koukouni P. Kone, Nelson Fumo

Mechanical Engineering Faculty Publications and Presentations

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 to control temperature, dehumidification is also provided. However, as houses are becoming more efficient, supplemental dehumidification is often necessary for homes located in hot and humid climates to control relative humidity intentionally. This study compared the dehumidification performance of a residential air conditioning system working in three operations modes to emulate three different systems: a system with a variable speed mode, a single-speed system with an enhanced dehumidification mode, and a single-speed system operating in a …

Power And Voltage Modelling Of A Proton-Exchange Membrane Fuel Cell Using Artificial Neural Networks, Tabbi Wilberforce, Mohammad Biswas, Abdelnasir Omran

Mechanical Engineering Faculty Publications and Presentations

A proton exchange membrane fuel cell (PEMFC) is a more environmentally friendly alternative to deliver electric power in various applications, including in the transportation industry. As PEMFC performance characteristics are inherently nonlinear and involved, the prediction of the performance in a given application for different operating conditions is important in order to optimize the efficiency of the system. Thus, modelling using artificial neural networks (ANNs) to predict its performance can significantly improve the capabilities of handling the multi-variable nonlinear performance of the PEMFC. However, further investigation is needed to develop a dynamic model using ANNs to predict the transient behavior …

Incorporation Of Torsion Springs In A Knee Exoskeleton For Stance Phase Correction Of Crouch Gait, Katy Baker Bumbard, Harold Herrington, Chung-Hyun Goh, Alwathiqbellah Ibrahim

Mechanical Engineering Faculty Publications and Presentations

Crouch gait is a motor complication that is commonly associated with cerebral palsy, spastic diplegia, stroke, and motor-neurological pathologies, broadly defined as knee flexion in excess of 20° in the gait cycle. Uncorrected crouch gait results in fatigue, joint degradation, and loss of ambulation. Torsion springs have been used in cycling to store energy in the knee flexion to reduce fatigue in the quadriceps during knee extension. SolidWorks was used to design a passive exoskeleton for the knee, incorporating torsion springs of stiffnesses 20,000 N/mm and 30,000 N/mm at the knee joint, to correct four different crouch gaits. OpenSim was …

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 …

A Review Of Ductless Mini Split Hvac System, Manoj Bhandari, Nelson Fumo

Mechanical Engineering Faculty Publications and Presentations

Although a conventional ducted system is the HVAC system used by most of the household in the United States, the ductless mini split system is gaining popularity in the market. The ductless mini split heat pump system consists of an outdoor unit that provides hot or cold refrigerant into a house to one or more wall- or ceiling-mounted indoor fan units. Ductless mini splits can have several advantages over conventional systems including improved thermal comfort, performance, and energy saving. There have been several studies and research in the field of ductless mini splits to learn about the advantages and disadvantages …

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 …

Characterizing The Effect Of Adding Boron Nitride Nanotubes On The Mechanical Properties Of Electrospun Polymer Nanocomposite Microfibers Mesh, Ohood Alsmairat, Nael Barakat

Mechanical Engineering Faculty Publications and Presentations

Electrospun fibrous meshes have a variety of applications such as filtration, drug delivery, energy storage, and engineered tissues due to their high surface area to mass ratio. Therefore, understanding the mechanical properties of these continuously evolving meshes is critical to expand and improve their performance. In this study, the effect of adding Boron Nitride Nanotube (BNNT) to Polymethylmethacrylate (PMMA) composite meshes on the mechanical properties of the polymer is studied. Electrospinning is used to fabricate microfiber meshes of PMMA and BNNT-PMMA. The fabricated meshes are tested experimentally with a uniaxial tensile tester. In addition, a theoretical model is introduced to …

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 …

Using Artificial Neural Network And Fuzzy Inference System Based Prediction To Improve Failure Mode And Effects Analysis: A Case Study Of The Busbars Production, Saeed Na’Amnh, Muath Bani Salim, István Husti, Miklós Daróczi

Mechanical Engineering Faculty Publications and Presentations

Nowadays, Busbars have been extensively used in electrical vehicle industry. Therefore, improving the risk assessment for the production could help to screen the associated failure and take necessary actions to minimize the risk. In this research, a fuzzy inference system (FIS) and artificial neural network (ANN) were used to avoid the shortcomings of the classical method by creating new models for risk assessment with higher accuracy. A dataset includes 58 samples are used to create the models. Mamdani fuzzy model and ANN model were developed using MATLAB software. The results showed that the proposed models give a higher level of …

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 …

Non Uniform Rational B-Splines And Lagrange Approximations For Time-Harmonic Acoustic Scattering: Accuracy And Absorbing Boundary Conditions, S.M. Dsouza, T. Khajah, X. Antoine, S.P.A. Bordas, S. Natarajan

Mechanical Engineering Faculty Publications and Presentations

The paper aims to evaluate the performance of the Lagrange-based finite element method and the non-uniform rational B-splines isogeometric analysis of time-harmonic acoustic exterior scattering problems using high-order local absorbing boundary conditions, in particular based on the Karp's and Wilcox's far-field expansions. The analysis of accuracy and convergence of both methods is achieved by observing the effect of the order of the approximating polynomial, the number of degrees of freedom, the wave number, and the absorbing boundary conditions tuning parameters. It is concluded that, regardless of the polynomial order, IGA provides a higher accuracy per degree of freedom compared to …

Triboelectric Energy Harvester With Large Bandwidth Under Harmonic And Random Excitations, Alwathiqbellah Ibrahim, Abdallah Ramini, Shahrzad Towfighian

Mechanical Engineering Faculty Publications and Presentations

This paper investigates an approach to impact vibration energy harvesting using a triboelectric mechanism under harmonic and random excitation. The harvester consists of a clamped–clamped beam with a stiff plate in the middle to realize the impact electrification process when subjected to external vibrations. The harvester uses stiffening in the clamped–clamped beam introduced by the impact between two triboelectric layers to increase the frequency bandwidth. A piecewise theoretical model is used to model the harvester for two scenarios of motions, before and after impact. The harvester is tested experimentally under different harmonic excitation to validate the theoretical model. The outcomes …

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. …

Thermal And Physico-Mechanical Characterizations Of Thromboresistant Polyurethane Films, Aaron C. Wilson, Shih-Feng Chou, Roberto Lozano, Jonathan Y. Chen, Pierre F. Neuenschwander

Mechanical Engineering Faculty Publications and Presentations

Hemocompatibility remains a challenge for injectable and/or implantable medical devices, and thromboresistant coatings appear to be one of the most attractive methods to down-regulate the unwanted enzymatic reactions that promote the formation of blood clots. Among all polymeric materials, polyurethanes (PUs) are a class of biomaterials with excellent biocompatibility and bioinertness that are suitable for the use of thromboresistant coatings. In this work, we investigated the thermal and physico-mechanical behaviors of ester-based and ether-based PU films for potential uses in thromboresistant coatings. Our results show that poly(ester urethane) and poly(ether urethane) films exhibited characteristic peaks corresponding to their molecular configurations. …

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 …