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Articles 1 - 30 of 93
Full-Text Articles in Mechanical Engineering
Predictions Of Indentation Stiffness Of Musculoskeletal Regions Using Ultrasound, Sean Doherty
Predictions Of Indentation Stiffness Of Musculoskeletal Regions Using Ultrasound, Sean Doherty
ETD Archive
Tissue indentation response is an important metric for understanding how different musculoskeletal regions respond to loading and is a function of the tissue’s form. Modem imaging techniques provide information about the internal structures of human tissue. Ultrasound remains one of the most common imaging techniques performed, given its portability and low costs. Prior work and data collection on 100 patients involved the collection of ultrasound images at eight different locations across the musculoskeletal extremities. Given the tissue structure information that the medical imaging provided, it was hypothesized that the mechanical properties of the tissue could be predicted from this data. …
Strengthening Effects Of Carbon Nanotubes And Graphene Nanoplatelets Reinforced Nickel Metal Matrix Composites, Amit Patil
ETD Archive
Carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) with superior mechanical, thermal, chemical, and electrical properties are appealing reinforcements for the fabrication of lightweight, high-strength, and wear-resistant metal matrix composites with outstanding mechanical and tribological performance. The nickel-carbon nanotube composites (Ni-CNT) and nickel-graphene nano-platelet composites (Ni-GNP) were processed using two separate ball milling methods, namely dry ball milling (DM) and solution ball milling (SBM), and then sintered using the spark plasma sintering (SPS) technique. The influence of the premixing process, milling time, reinforcement morphology, and concentration on matrix grain size, microstructure, dispersion in the nickel matrix, mechanical properties, and tribological performance …
Mechanistic Understanding Of Phase Stability, Transformation, And Strengthening Mechanisms In Lightweight High Entropy Alloys And High Entropy Ceramics, Ganesh Walunj
ETD Archive
High-entropy alloys (HEAs) are a novel family of solid-solution alloys that have gained international interest due to their exceptional characteristics. Because of the need from the transportation and defense sectors, lightweight HEAs have attracted researcher’s curiosity as prospective advanced materials. Low-weight high entropy alloy synthesizes using arc melting with a mass ratio of AlCrFeMnTix(0.1,0.15,0.2). The synthesized HEA is comprised of a mixture of body center cubic (bcc) and ordered bcc (L21) solid solution phases. The synthesized HEAs have heat treated at 650C, 800C, and 1150C for 1hr, 4hr after solutionized at 1150C for 2 hr to understand the effect of …
Mechanistic Undrestanding Of Amorphization In Iron-Based Soft Magnetic Materials, Taban Larimian
Mechanistic Undrestanding Of Amorphization In Iron-Based Soft Magnetic Materials, Taban Larimian
ETD Archive
Iron-based magnetic alloys possess very good magnetic and mechanical properties. Among these alloys Fe-Si-B-based alloys show outstanding saturation magnetization and coercivity which makes them great candidates for many industrial applications. Addition of certain elements to the Fe-Si-B base is proven to improve the homogeneity and fineness of microstructure as well as enhance the magnetic behavior of these alloys. In this research work, we have studied the effect of adding copper and niobium to the Fe-Si-B base alloy. Previous studies have shown that magnetic alloys show better magnetic properties when their microstructure consists of nanocrystals embedded in an amorphous matrix. In …
Viability And Accessibility Of Urban Heat Island And Lake Microclimate Data Over Current Tmy Weather Data For Accurate Energy Demand Predictions., Irena A. Weclawiak
Viability And Accessibility Of Urban Heat Island And Lake Microclimate Data Over Current Tmy Weather Data For Accurate Energy Demand Predictions., Irena A. Weclawiak
ETD Archive
Building Energy Simulations (BES) are necessary for designing energy-efficient systems. Open-source simulation software developed by the Department of Energy (DOE), EnergyPlus (EP) provides Typical Meteorological Year (TMY) weather data that consists of a 15-year average. Two major concerns about this data are the inability to detect extreme conditions and limited data locations. There is a greater number of Microclimate (MC) stations that can be used for simulations, but it involves time-consuming data preparation to match the EP format. This study investigated the effects of Urban Heat Island (UHI) and the MC of Lake Erie. A comparison of the MC data …
An Evaluation And Economic Analysis Of A Water Main Geothermal System In A Residential Space, Brian L. Kohut
An Evaluation And Economic Analysis Of A Water Main Geothermal System In A Residential Space, Brian L. Kohut
ETD Archive
Iron-based magnetic alloys possess very good magnetic and mechanical properties. Among these alloys Fe-Si-B-based alloys show outstanding saturation magnetization and coercivity which makes them great candidates for many industrial applications. Addition of certain elements to the Fe-Si-B base is proven to improve the homogeneity and fineness of microstructure as well as enhance the magnetic behavior of these alloys. In this research work, we have studied the effect of adding copper and niobium to the Fe-Si-B base alloy. Previous studies have shown that magnetic alloys show better magnetic properties when their microstructure consists of nanocrystals embedded in an amorphous matrix. In …
Achieving Practical Functional Electrical Stimulation-Driven Reaching Motions In An Individual With Tetraplegia, Derek Nathaniel Wolf
Achieving Practical Functional Electrical Stimulation-Driven Reaching Motions In An Individual With Tetraplegia, Derek Nathaniel Wolf
ETD Archive
Functional electrical stimulation (FES) is a promising technique for restoring the ability to complete reaching motions to individuals with tetraplegia due to a spinal cord injury (SCI). FES has proven to be a successful technique for controlling many functional tasks such as grasping, standing, and even limited walking. However, translating these successes to reaching motions has proven difficult due to the complexity of the arm and the goaldirected nature of reaching motions. The state-of-the-art systems either use robots to assist the FES-driven reaching motions or control the arm of healthy subjects to complete planar motions. These controllers do not directly …
Design, Control, And Optimization Of Robots With Advanced Energy Regenerative Drive Systems, Poya Khalaf
Design, Control, And Optimization Of Robots With Advanced Energy Regenerative Drive Systems, Poya Khalaf
ETD Archive
We investigate the control and optimization of robots with ultracapacitor based regenerative drive systems. A subset of the robot joints are conventional, in the sense that external power is used for actuation. Other joints are energetically self-contained passive systems that use ultracapacitors for energy storage. An electrical interconnection known as the star configuration is considered for the regenerative drives that allows for direct electric energy redistribution among joints, and enables higher energy utilization efficiencies. A semi-active virtual control strategy is used to achieve control objectives. We find closed-form expressions for the optimal robot and actuator parameters (link lengths, gear ratios, …
Advanced Processing Of Nickel-Titanium-Graphite Based Metal Matrix Composites, Amit K. Patil
Advanced Processing Of Nickel-Titanium-Graphite Based Metal Matrix Composites, Amit K. Patil
ETD Archive
A new class of in situ titanium carbide (TiC)/graphite (C) reinforced nickel matrix composites with variation in composition particularly varying C/Ti ratio have been processed using two different processing techniques. Firstly, via mechanical alloying (MA) followed by spark plasma sintering (SPS), i.e. solid-state processing. Secondly, using Laser engineered net shaping (LENSTM) technique, i.e. metal additive manufacturing technique. Mechanical alloying has gained special attention as a powerful non-equilibrium process for fabricating amorphous and nanocrystalline materials, whereas spark plasma sintering is a unique technique for processing dense and near net shape bulk alloys with homogeneous microstructure. Laser engineered net shaping (LENSTM) is …
A Reticulation Of Skin-Applied Strain Sensors For Motion Capture, Christopher A. Schroeck
A Reticulation Of Skin-Applied Strain Sensors For Motion Capture, Christopher A. Schroeck
ETD Archive
The purpose of this research is to develop a system of motion capture based on skin-applied strain sensors. These elastic sensors are of interest because they can be applied to the body without restricting motion and are well suited to operate in more practical environments, such as sports fields, gymnasiums, and outdoor areas. This combination is currently not available in the field of motion capture. The current issues with strain sensor motion capture technology is the accurate is not sufficient for motion analysis and axial rotation monitoring of joints is not available. This project will build and test a sensor …
Robust Impedance Control Of A Four Degree Of Freedom Exercise Robot, Santino Joseph Bianco
Robust Impedance Control Of A Four Degree Of Freedom Exercise Robot, Santino Joseph Bianco
ETD Archive
The CSU 4OptimX exercise robot provides a platform for future research into advanced exercise and rehabilitation. The robot and its control system will autonomously modify reference trajectories and impedances on the basis of an optimization criterion and physiological feedback. To achieve this goal, a robust impedance control system with trajectory tracking must be implemented as the foundational control scheme. Two control laws will be compared, sliding mode and H-infinity control. The above robust control laws are combined with underlying impedance control laws to overcome uncertain plant model parameters and disturbance anomalies affecting the input signal. The sliding mode control law …
Neuromuscular Reflex Control For Prostheses And Exoskeletons, Sandra K. Hnat
Neuromuscular Reflex Control For Prostheses And Exoskeletons, Sandra K. Hnat
ETD Archive
Recent powered lower-limb prosthetic and orthotic (P/O) devices aim to restore legged mobility for persons with an amputation or spinal cord injury. Though various control strategies have been proposed for these devices, specifically finite-state impedance controllers, natural gait mechanics are not usually achieved. The goal of this project was to invent a biologically-inspired controller for powered P/O devices. We hypothesize that a more muscle-like actuation system, including spinal reflexes and vestibular feedback, can achieve able-bodied walking and also respond to outside perturbations. The outputs of the Virtual Muscle Reflex (VMR) controller are joint torque commands, sent to the electric motors …
Human Activity Tracking And Recognition Using Kinect Sensor, Roanna Lun
Human Activity Tracking And Recognition Using Kinect Sensor, Roanna Lun
ETD Archive
The objective of this dissertation research is to use Kinect sensor, a motion sensing input device, to develop an integrated software system that can be used for tracking non-compliant activity postures of consented health-care workers for assisting the workers' compliance to best practices, allowing individualized gestures for privacy-aware user registration, movement recognition using rule-based algorithm, real-time feedback, and exercises data collection. The research work also includes developing a graphical user interface and data visualization program for illustrating statistical information for administrator, as well as utilizing cloud based database system used for data resource.
Non-Intrusive Optical Measurement Of Electron Temperature In Near Field Plume Of Hall Thruster, Peter J. Urban
Non-Intrusive Optical Measurement Of Electron Temperature In Near Field Plume Of Hall Thruster, Peter J. Urban
ETD Archive
Currently there is a large interest in the use of more efficient means of propulsion in long term missions due to the costs and difficulties associated with placing and maintaining the needed fuel for conventional chemical systems in orbit. Mass reduction of upper stages will return large returns due to the great reduction in required lower stage fuel. Due to these factors, alternatives are undergoing active research, though this paper is concerned with the area of electrical propulsion. Electric propulsion is broadly defined as propulsion where the energization of the exhaust occurs via application of electromagnetic fields as opposed to …
Predictive Simulations Of Gait And Their Application In Prosthesis Design, Anne D. Koelewijin
Predictive Simulations Of Gait And Their Application In Prosthesis Design, Anne D. Koelewijin
ETD Archive
Predictive simulations predict human gait by solving a trajectory optimization problem by minimizing energy expenditure. These simulations could predict the effect of a prosthesis on gait before its use. This dissertation has four aims, to show the application of predictive simulations in prosthesis design and to improve the quality of predictive simulations. Aim 1 was to explain joint moment asymmetry in the knee and hip in gait of persons with a transtibial amputation (TTA gait). Predictive simulations showed that an asymmetric gait required less effort. However, a small effort increase yielded a gait with increased joint moment symmetry and reduced …
Advanced Manufacturing Of Titanium Alloys For Biomedical Applications, Nicholas C. Mavros
Advanced Manufacturing Of Titanium Alloys For Biomedical Applications, Nicholas C. Mavros
ETD Archive
In metallurgy, Titanium has been a staple for biomedical purposes. Its low toxicity and alloying versatility make it an attractive choice for medical applications. However, studies have shown the difference in elastic modulus between Titanium alloys (116 GPa) and human bone (40-60 GPa) contribute to long term issues with loose hardware fixation. Additionally, long term studies have shown elements such as Vanadium and Aluminum, which are commonly used in Ti-6Al-4V biomedical alloys, have been linked to neurodegenerative diseases like Alzheimers and Parkinsons. Alternative metals known to be less toxic are being explored as replacements for alloying elements in Titanium alloys. …
An Anisotropic Constitutive Model For Nuclear Grade Graphite, James Christopher
An Anisotropic Constitutive Model For Nuclear Grade Graphite, James Christopher
ETD Archive
Graphite material is used extensively in nuclear reactors however the material has a limited strain range for elastic behavior. This provides the motivation to derive a constitutive model that captures the inelastic deformations exhibited by this material. This dissertation first presents details of an isotropic constitutive model derived using continuum principles of engineering mechanics that accounts for different inelastic behavior in tension and compression. An inelastic dissipation function was developed using an integrity basis proposed by Green and Mkrtichian (1977) for the isotropic version of the model. This isotropic model was then extended to capture anisotropic stress-strain behavior using directional …
Design And Control Of A Powered Rowing Machine With Programmable Impedance, Jose Humberto De La Casas Zolezzi
Design And Control Of A Powered Rowing Machine With Programmable Impedance, Jose Humberto De La Casas Zolezzi
ETD Archive
Due to the rise of obesity, diabetes and cardiovascular disease, research in human performance and physical activity has received increased attention. Rowing machines are used for performance improvements through concentric exercises, however a combination of concentric and eccentric actions is known to improve the effectiveness of training. In this work, a conventional rowing machine was modified to include an electric motor and a robust impedance control system, enabling programmable impedance with concentric and eccentric capabilities. Eccentric exercises are known to contribute significantly to the efficacy of training and to diminish the detrimental effects of humans operating in microgravity for long …
Forming A Metal Matrix Nanocomposite (Mmnc) With Fully Dispersed And Deagglomerated Multiwalled Carbon Nanotubes (Mwcnts), Mahesh Kumar Pallikonda
Forming A Metal Matrix Nanocomposite (Mmnc) With Fully Dispersed And Deagglomerated Multiwalled Carbon Nanotubes (Mwcnts), Mahesh Kumar Pallikonda
ETD Archive
Carbon Nanotubes (CNTs) with their exceptional properties will facilitate the Metal matrix composites (MMC) to exhibit good mechanical properties, thermal and electrical conductivities, corrosion resistance, etc. The critical factor that holds the development of the Metal matrix Nanocomposites (MMNC) by using CNTs is the tendency of CNTs to form clusters (agglomerations) due to their high Van der Waals attractions. Due to this factor, low density and other properties of the CNTs, there has been a delay in harnessing their ultimate potential.
Existing literature in contemporary times from the works of few researches in Nanocomposites shows the prevalence of using surfactants …
Piv Analysis Of Wake Structure Of Real Elephant Seal Whiskers, Joseph Antun Bunjevac
Piv Analysis Of Wake Structure Of Real Elephant Seal Whiskers, Joseph Antun Bunjevac
ETD Archive
Seals are able to accurately detect minute disturbances in the ambient flow
environment using their whiskers, which is attributed to the exceptional capability of
their whiskers to suppress vortex-induced vibrations in the wake. To explore potential applications for designing smart flow devices, such as high-sensitivity underwater
flow sensors and drag reduction components, researchers have studied how the role
of some key parameters of whisker-like morphology affect the wake structure. Due to
the naturally presented variation in size and curvature along the length of whiskers,
it is not well understood how a real whisker changes the surrounding flow and the
vortex …
Investigation Of Extremum Seeking Control For Adaptive Exercise Machines, Brahm T. Powell
Investigation Of Extremum Seeking Control For Adaptive Exercise Machines, Brahm T. Powell
ETD Archive
Many muscle rehabilitation regimens are non-adaptive and recommended subjectively by physicians. While there are advantages to having the feedback of a qualified physician, utilizing real-time muscle performance feedback could be beneficial. An extremum seeking control design is proposed to fulfill the need for an automated, load-varying exercise machine that can optimize muscle performance.
Several steps are outlined to contribute to the realization of this goal. First, the extremum seeking control scheme is discussed. Second, the Hill muscle model will be described. Theoretical muscle effort extrema will be derived for selected optimization cases, namely maximizing average squared power by varying load …
Experimental Investigation Of Turbulent Flow Induced By New-Generation Wind Fences With Multi-Scale Fractal Structure, Sarah M. Mcclure
Experimental Investigation Of Turbulent Flow Induced By New-Generation Wind Fences With Multi-Scale Fractal Structure, Sarah M. Mcclure
ETD Archive
Understanding and controlling atmospheric boundary-layer flows with engineered structures, such as porous wind fences or windbreaks, has been of great interest to the fluid mechanics and wind engineering community. Previous studies found that the regular mono-scale grid fence of 50% porosity and a bottom gap of 10% of the fence height are considered to be optimal over a flat surface. Significant differences in turbulent flow structure have recently been noted behind multi-scale fractal wind fences, even with the same porosity. In this study, wind-tunnel tests on the turbulent flow and the turbulence kinetic energy transport of 1D and 2D multi-scale …
A Simulation And Experimental Study Of Active Disturbance Rejection For Industrial Pressure Control, Xiaoxu Li
A Simulation And Experimental Study Of Active Disturbance Rejection For Industrial Pressure Control, Xiaoxu Li
ETD Archive
The quality of control loop is very important in hydraulic machineries, where pressure must be accurately regulated in the presence of various disturbances. Proportional-Integral-Derivative (PID) control has dominated the industry for a long time and it is by far the most popular general purpose controller for pressure control. The purpose of this study is to conduct a simulation and experimental study comparing PID with an emerging new technology, namely active disturbance rejection control (ADRC). For the purpose of this study, an experimental testbed similar to those used in industry settings is used; its mathematic model is derived and used in …
Characterization Of Performance Of A 3d Printed Stirling Engine Through Analysis And Test, Julie Vodhanel
Characterization Of Performance Of A 3d Printed Stirling Engine Through Analysis And Test, Julie Vodhanel
ETD Archive
This thesis involves the fusion of two technologies, Stirling engines and additive
manufacturing. The project began by building a Stirling engine primarily out of 3D printed parts. Methods to measure the power output were designed and built with a combination of 3D printed and off the shelf parts. The Stirling engine was tested to see if there was a correlation to analysis results, and a regenerator was installed to determine the effect on performance for this relatively low temperature engine. Finally, variations in test operation and the use of heat sinks were used to find a combination that will allow …
Analytical And Numerical Validation Of Nozzle Spray Measurement Data Obtained From A Newly Developed Production System, Iddrisu Seidu
Analytical And Numerical Validation Of Nozzle Spray Measurement Data Obtained From A Newly Developed Production System, Iddrisu Seidu
ETD Archive
A newly developed production test stand for measuring the spray angle of a pressure swirl atomizer was constructed and used to measure a product line of these pressure swirl atomizers -- the macrospray atomizer. This new test stand, utilizing constant temperature hot wire anemometers, captures the spray angle data based on the voltage drop the hot wire probes see as they traverse the spray cone of the atomizer and as fluid droplets impinge upon the wire. Datasets acquired from the experiments are compared and correlated with computational fluid dynamics (CFD) simulation data. In addition, angles obtained from another type of …
Dynamic Model Of A Non-Linear Pneumatic Pressure Modulating Valve Using Bond Graphs, Christopher L. Brubaker
Dynamic Model Of A Non-Linear Pneumatic Pressure Modulating Valve Using Bond Graphs, Christopher L. Brubaker
ETD Archive
This research develops a mathematical model of the dynamic pressure response to a variable travel input of a pneumatic pressure modulating valve intended for use in a vehicle air brake system. Generically, the valve is a multi-domain system consisting of a mechanical portion and a pneumatic portion. Included in the mechanical portion of the model are compliance of the springs, inertia of the components, and resistance of the sliding components. The pneumatic portion of the model includes capacitance due to the compressibility of the gas, flow resistance through connected plumbing, and flow resistance through the valve control orifices. The development …
Optimal Design And Control Of A Lower-Limb Prosthesis With Energy Regeneration, Holly E. Warner
Optimal Design And Control Of A Lower-Limb Prosthesis With Energy Regeneration, Holly E. Warner
ETD Archive
The majority of amputations are of the lower limbs. This correlates to a particular need for lower-limb prostheses. Many common prosthesis designs are passive in nature, making them inefficient compared to the natural body. Recently as technology has progressed, interest in powered prostheses has expanded, seeking improved kinematics and kinetics for amputees. The current state of this art is described in this thesis, noting that most powered prosthesis designs do not consider integrating the knee and the ankle or energy exchange between these two joints. An energy regenerative, motorized prosthesis is proposed here to address this gap. After preliminary data …
Development Of Chatter Attenuation Robust Control For An Amb Machine Spindle, Alexander Hans Pesch
Development Of Chatter Attenuation Robust Control For An Amb Machine Spindle, Alexander Hans Pesch
ETD Archive
No abstract provided.
Numerical Investigation Of Boiling In A Sealed Tank In Microgravity, Sonya Lynn Hylton
Numerical Investigation Of Boiling In A Sealed Tank In Microgravity, Sonya Lynn Hylton
ETD Archive
NASA's missions in space depend on the storage of cryogenic fluids for fuel and for life support. During long-term storage, heat can leak into the cryogenic fluid tanks. Heat leaks can cause evaporation of the liquid, which pressurizes the tank. However, when the tanks are in a microgravity environment, with reduced natural convection, heat leaks can also create superheated regions in the liquid. This may lead to boiling, resulting in much greater pressure rises than evaporation at the interface between the liquid and vapor phases. Models for predicting the pressure rise are needed to aid in developing methods to control …
Development Of Test Methodology For Evaluation Of Fuel Economy In Motorcycle Engines, Alexander Michlberger
Development Of Test Methodology For Evaluation Of Fuel Economy In Motorcycle Engines, Alexander Michlberger
ETD Archive
Rising fuel costs and concerns over fossil fuel emissions have resulted in more stringent fuel economy and emissions standards globally. As a result, motor vehicle manufacturers are constantly pushed to develop more efficient engine and drivetrain systems. Along with advances in hardware, the development of highly fuel efficient engine oils and driveline lubricants can have a significant impact on total system efficiency. Recently motorcycle fuel economy and emissions have come under increased scrutiny. While the passenger vehicle and heavy duty vehicle industries employ a variety of American Society for Testing and Materials (ASTM) standardized tests to measure fuel economy and …