Department: Mechanical Engineering (Engineering and Technology) ![[clear]](close-x.png "Remove this limiter")
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1.
Allen, Jeremy L.
The Effect of Baffle Arrangements on Flow Uniformity in a Manifold for a Unique Solid Oxide Fuel Cell Stack Design.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► Flow uniformity through channels of a complex fuel cell stack is studied…
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▼ Flow uniformity through channels of a complex fuel cell stack is studied for several baffle arrangements using ANSYS Fluent, a computational fluid dynamics (CFD) package. Flow mal-distribution occurs from pressure differentials throughout the flow structure and causes a drop in stack performance. Three baffle arrangements were introduced into the flow structure and compared to a control case with no baffle in an attempt to improve the flow regime. A flow uniformity coefficient Γ was introduced to compare results from case to case. It was found that all three arrangements significantly increased flow uniformity, with the slotted baffle arrangement providing the most uniform flow. By increasing flow uniformity, the efficiency of the stack is also increased.
Advisors/Committee Members: Bayless, David.
Subjects: Engineering; Fluid Dynamics; Mechanical Engineering
Keywords: SOFC; fuel cell; Simulation; CFD; ANSYS Fluent; manifold; baffle; uniform flow
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2.
Anthony, Renil J.
Solvent Extraction of Lipids from Microalgae.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2010, Ohio University
► Algae are a favorable feedstock for biodiesel due to their high oil…
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▼ Algae are a favorable feedstock for biodiesel due to their high oil content and fast growth rate. The average oil content has been found to be 20-50% of dry weight. Solvent lipid extraction efficiency from algae is strain specific and with the focus on neutral lipids, four non-polar solvents were tested on Oocystis sp. Methylene chloride, hexane, diethyl ether and cyclohexane were chosen, and the extractions performed in a soxhlet apparatus. The lipid extracts were derivatized and analyzed using a combination of Gas Chromatography-Mass Spectrometry. All four solvent extracts showed the same composition of hexadecanoic acid methyl ester (C16:0), linoleic acid methyl ester(C18:2) and linolenic acid methyl ester (C18:3) with the same % wt composition. Among the four, methylene chloride proved to be the most efficient solvent for Oocystis sp. with a total neutral lipid recovery of 0.25% of dry weight followed by diethyl ether,cyclohexane and hexane. The results question the use of the algal strain Oocystis sp. for biofuels. The lipid productivity in Oocystis sp. would need to be verified and a more efficient solvent and/or extraction technique identified, or an algal strain having higher lipid productivity should be employed for biofuel feedstock.
Advisors/Committee Members: Stuart, Benjamin.
Subjects: Botany; Energy; Engineering; Environmental science; Mechanical engineering
Keywords: Algae; Biodiesel; Oocystis; Solvent Extraction; Soxhlet; Microalgae
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3.
Burke, Thomas A.
Modification and Validation of a Novel Solid-Liquid Separation Technique Using a Microscreen and Capillary Belt System.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2012, Ohio University
► One of the major contributors to high processing costs of microalgae for…
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▼ One of the major contributors to high processing costs of microalgae for biofuel is the harvesting and dewatering of the microalgae, which can account for 20-30% of the total cost. Microalgae can potentially become a more economical feedstock for biofuel if the capital and operational costs of the harvesting/dewatering step are reduced by using a novel microscreen and capillary belt system. By modifying the well section of the Algaeventure Systems prototype harvester, the flow rate of live Scenedesmus dimorphus algae through the harvester system was increased by an average of 166.8% and the power consumption per unit mass was decreased by an average of 51.4%. A modified testing rig was also constructed to eliminate a belt tracking and media spill-over issue through development of an autonomous belt tracking system. Chlorella powder and tomato juice were tested under the same conditions as the live algae to determine a suitable surrogate material to live algae.
Advisors/Committee Members: Stuart, Ben.
Subjects: Mechanical Engineering
Keywords: Microalgae; Harvesting; Dewatering; microscreen; capillary belt; Algaeventure Systems; AVS; biofuel; biodiesel; Scenedesmus dimorphus; algae; microalgae processing
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4.
Chen, Meng-Yun.
The Virtual Haptic Human Upper Body for Palpatory Diagnostic Training.
Degree: PhD, Mechanical Engineering (Engineering and Technology), 2010, Ohio University
► Modern virtual medical simulators have many advantages over their manikin counterparts. For…
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▼ Modern virtual medical simulators have many advantages over their manikin counterparts. For example, they are more repeatable and reconfigurable. The virtual reality can be upgraded and modified to serve different training purposes. The goal of the Virtual Haptic Human Upper Body (VHHUB) research is to create a physiologically-correct human upper body for osteopathic medical gross motion palpation training using haptics and virtual reality technologies. The virtual human upper body is a 71 degrees-of- freedom multiple end-effectors, multi-branching serial chain model. It has fully movable thoracic and lumbar spinal regions plus two shoulders and two arms with a deformable body. Due to the complexity of the VHHUB model, we present a velocity inverse kinematic problem solver with dynamic pivot point. This method ensures a smooth synchronization rate between graphics and haptic hardware in real time. Fryette’s principles are implemented in the VHHUB. Fryette’s principles are one of the fundamental theories for the osteopathic manipulative medicine (OMM) to diagnose somatic dysfunctions. The VHHUB software is developed in a way to help osteopathic physicians or OMM fellows fine tune the program for their student’s training. The haptic feedback of somatic dysfunctions can be modified by OMM faculty administrators without any knowledge of programming languages. The VHHUB provides an additional training tool for the osteopathic medical students to augment their osteopathic manipulative medicine (OMM) laboratory courses. VHHUB evaluation and recommendations for future research are presented. From the preliminary evaluation data, most medical students gave 7 or up (scale from 1 to 10: 1 is unrealistic and 10 is realistic) on the realism of the VHHUB. Medical students also felt the simulation gave them a useful tool for learning Fryette’s principles.
Advisors/Committee Members: Williams II, Robert.
Subjects: Engineering; Mechanical engineering; Robots
Keywords: Virtual Haptic Human Upper Body; VHHUB; Palpatory Diagnostic Training; Virtual Haptic Back
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5.
Cyders, Timothy J.
Design of a Human-Powered Utility Vehicle for Developing Communities.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2008, Ohio University
► There is a need for many appropriate technologies in the developing world…
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▼ There is a need for many appropriate technologies in the developing world today. As international development efforts such as projects by Engineers Without Borders attempt to fulfill this need, the design process needs to be examined as it spans borders and cultures. This project examines the criteria for appropriate technology and design process steps through the execution of an appropriate technology development project from start to finish.The project executed was the development of a Human Powered Utility Vehicle to fulfill the transport needs of rural communities in Sub-Saharan Africa. In order to establish basic infrastructure, a sustainable, affordable method of transporting goods and services is essential. This research project fulfills this need by the design of an appropriate utility transportation solution for such communities, with multiple applications for farming and other productivity. The researcher took a total of three trips, two for assessment and benchmarking, and one for a final implementation of the design for customer feedback and performance testing. The design was also taught to local workers and made public-domain such that it can be produced if the design is successful.
Advisors/Committee Members: Kremer, Gregory G.
Subjects: Design; Engineering; Mechanical engineering; Social structure
Keywords: appropriate technology; Africa; Cameroon; Ghana; developing countries; human power; human powered utility vehicle
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6.
Dalne, Sarang G.
A Finite Element Simulation of the Temporomandibular Joint of a Pig.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2009, Ohio University
► Temporomandibular joint (TMJ) disorders affect 20 to 25% of the population and…
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▼ Temporomandibular joint (TMJ) disorders affect 20 to 25% of the population and include pain dysfunction, arthritis, and internal derangements. The pig is a common model due to its similar structure and mechanics to humans. This work represents the first finite element analysis (FEA) of pig TMJ. The primary objective was to investigate the stress distribution pattern in the TMJ articulating disc. The TMJ disc was defined as a Mooney-Rivlin material. Geometry was obtained from CT scans. Retrodiscal and TMJ ligaments were included as linear springs. The disc was considered glued to the mandible, but had frictionless contact with the temporal bone. Muscle loads were used to simulate clenching. It was observed that the TMJ disc followed the condylar motion. Also, significant lateral movement of the mandible was observed. The intermediate-lateral part of the disc was most stressed. The observed stresses were comparable to the human TMJ models in magnitudes and locations.
Advisors/Committee Members: Cotton, John.
Subjects: Engineering; Mechanical engineering; Mechanics
Keywords: Finite Element Analysis (FEA); Temporomandibular Joint (TMJ); Pig jaw; TMJ disk
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7.
Ding, Jun.
Mechanism Design, Kinematics and Dynamics Analysis of a 7-Degree-Of-Freedom (DOF) Cable-Driven Humanoid Robot Arm.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► The purpose of this thesis is to study a 7-DOF humanoid cable-driven…
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▼ The purpose of this thesis is to study a 7-DOF humanoid cable-driven robotic arm, implement kinematics and dynamics analysis, present different cable-driven designs and evaluate their merits and drawbacks. Since this is a redundant mechanism, kinematics optimization is used to avoid joint limits, singularities and obstacles. Cable kinematics analysis studies the relations between lengths of cables and pose of the end-effector. This is a design modified from the literature. Several new designs are compared in statics analysis of the whole arm and the most favorable design is suggested in terms of motion range and the consumption of cable tensions. Linear programming is used to optimize cable tensions. The energy consumption of the cable-driven arm is much less than that of the traditional motor-driven arm in dynamics analysis. Cable-driven robots have potential benefits but also some limitations.
Advisors/Committee Members: Williams, Robert.
Subjects: Mechanical Engineering; Robotics; Robots
Keywords: 7 DOF robotic arm; Cable-Driven; Kinematics; Dynamics
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8.
Edwards, Tyler A.
A Parametric Study of Stack Performance for a 4.8kW PEM Fuel Cell.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2010, Ohio University
► Parametric testing was conducted to determine the effects of reactant stream temperature,…
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▼ Parametric testing was conducted to determine the effects of reactant stream temperature, pressure, humidity and flow rate on the voltage and power output of a 4.8kW PEM fuel cell (FC) stack. The effect of physical orientation and coolant temperature on the voltage and power output of the FC stack is discussed. It was determined that the reactant flow rates could be reduced to approximately 90% of the manufacturer's recommended values without significantly affecting the performance of the FC stack. Increasing reactant stream temperature, pressure, and relative humidity increased the power output of the FC stack. The power output of the FC stack was shown to be sensitive to reactant stream temperatures. This effect was more pronounced for loads below approximately 100A. The power output of the FC stack was also observed to increase with increasing coolant temperature. This effect was greater for higher loads. Reactant stream pressure was observed to cause a nearly uniform shift in the ohmic region of the FC stack's polarization curve. The difference in the power output between the high and low pressures tested was approximately 8% from 0-200A load. The power output of the FC stack was not sensitive to changes in the reactant stream relative humidity for values above 70%. Reactant stream relative humidity was shown to have a more pronounced effect for loads less than 100A. The FC stack's physical orientation did not affect the stack's power output for inclinations less than 13.5°. The time required for the FC stack to reach a steady state voltage following abrupt load changes was not significantly different for different step sizes. The voltage observed within 0.1 seconds of all load changes was always within 2% of the steady state value. Based on the results of this study, the FC stack that was tested is well suited for its intended automotive application.
Advisors/Committee Members: Kremer, Greg.
Subjects: Mechanical engineering
Keywords: PEM; PEMFC; parametric study; effects; parameter sensitivity; stack orientation; dynamics; ammonia car
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9.
Fajardo Nino De Rivera, Vanessa.
Localized CO2 Corrosion in the Presence of Organic Acids.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► The organic acid content in oil wells plays a determining role in…
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▼ The organic acid content in oil wells plays a determining role in the severity of corrosion even when only small concentrations are present. Organic acids are weak Brønsted acids that exist mainly as undissociated molecular species. Like all weak acids, a certain moiety will dissociate to form hydrogen ions and an anionic conjugate base. Therefore, with these acids the corrosion rate is not influenced only by pH, but also by the concentration of the undissociated acids in the solution. The vast majority of the literature on the effect of organic acids on CO2 corrosion of carbon steel focuses on acetic acid because this acid is the most abundant in the mixture of organic acids seen in the field. The purpose of this project was to understand and determine the mechanistic role of organic acids on the initiation of localized corrosion. It was concluded that the presence of acetic acid may lead to damage of the protective iron carbonate scale formed on X65 carbon steel. This leads directly to a temporary increase in the corrosion rate. However, the final corrosion rate does not seem to be affected. This raises the possibility that there may be a different phase conferring protection on the steel surface. This phase (corrosion scale) was characterized using different analytical techniques (SEM, EDS, XRD, XPS and FIB/TEM/EDS) to provide a more complete understanding of the metal’s surface. It was found that the protection persisted as part of the FeCO3 remained on the surface. No localized attack was found under the studied conditions. In order to quantify iron carbonate dissolution, the electrochemical quartz crystal microbalance (EQCM) was used for the study of scale solubility in the presence of acetic acid. This confirmed that the presence of acetic acid was responsible for partial removal of the iron carbonate scale by selective dissolution, corroborating the characterization data obtained by surface analysis.
Advisors/Committee Members: Nesic, Srdjan.
Subjects: Materials Science
Keywords: CO2 corrosion, iron carbonate precipitation and dissolution, acetic acid, EQCM
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10.
Flores-Lozada, Juan G.
Copper Micro-channel Loop Thermosyphon.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2009, Ohio University
► The purpose of this work was to use copper micro-channel tube to…
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▼ The purpose of this work was to use copper micro-channel tube to design, construct and analyze the performance of a loop thermosyphon prototype. The design stage included a pressure loss analysis to ensure working fluid circulation. Analytical, numerical and experimental analyses were performed to calculate the heat transfer coefficient and heat transfer and to compare the results. The analytical analyses consisted of estimations of the heat transfer coefficient and heat transfer with the fin theory, and flow over a flat surface. The numerical analysis was performed using the computational fluid dynamics software Fluent. The experimental work was conducted on a small-scale wind tunnel under constant air flow, 0.5 and 1.0 m/s, and different operating temperatures, ~50°C and ~70°C. Propane was chosen as the working fluid for the system due to its relatively low global warming potential, saturation temperature range, availability, ease of storage, and non toxic properties. This work confirmed the concept of a loop thermosyphon by providing an isothermal surface throughout the prototype. The isothermal fins increased the heat transfer by a maximum of 63% compared to the classical fin mode.
Advisors/Committee Members: Alam, Khairul.
Subjects: Mechanical engineering
Keywords: heat transfer; micro channels; loop thermosyphon; heat exchanger; isothermal fins; copper
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11.
Garg, Deepak.
Simulation of Thermal Transport in a Nanocomposite Blow Mold.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2009, Ohio University
► The thermal design of a nanocomposite mold for the blow molding process…
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▼ The thermal design of a nanocomposite mold for the blow molding process has been studied. For low production cycles, there is a significant interest in using lower cost composite molds to replace the expensive traditional metal molds used in the blow molding process. A critical issue in using a polymer matrix composite as an alternative to a metal for mold material is the large difference in the thermal transport properties. The composite mold design must integrate enhanced cooling so that the product can cool sufficiently within a short cycle time. Nanocomposites that use carbon nanofiber offer improvements in thermal and mechanical properties; therefore they are potential candidates for making molds for polymer products. This project describes the design of a nanocomposite blow mold using numerical simulations of the thermal transport in the mold and the stress analysis of the final blow molded product.
Advisors/Committee Members: Alam, Khairul.
Subjects: Mechanical engineering; Plastics; Polymers
Keywords: Blow Mold; Nanocomposite; Polymer processing; Viscoelastic flow; Thermal design
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12.
Harris, James C.
Wind Energy Assessment and Visualization Laboratory Extra-Tall Tower Wind Resource Assessment: Icing Rules and Trends in the Data.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2012, Ohio University
► This study describes the results of the measurement campaign for the Wind…
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▼ This study describes the results of the measurement campaign for the Wind Energy Assessment and Visualization Laboratory (WEAV) wind feasibility study in Athens, OH. A detailed procedure for acquiring and processing meteorological data from the WOUB tower location is included. An in-depth analysis of screening the data for events involving the icing of anemometers shows the most efficient way for flagging the data set. Results of the screening were used to recognize icing conditions on the meteorological tower for future wind resource assessment. An optimized rule-based approach was created to accurately and efficiently screen the data affected by icing. Over the 24 months, a final wind shear exponent of 0.453 and surface roughness of 9.16 meters was found. A wind speed of 4.5 m/s was found at 80 meters using the power law. An estimated cost analysis found that wind energy development was not currently feasible at the WOUB tower location based on two years of data.
Advisors/Committee Members: Womeldorf, Carole.
Subjects: Mechanical Engineering
Keywords: wind resource assessment; anemometer icing; wind energy; Southeast Ohio wind potential
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13.
Hincapie, Esteban.
Design, Construction and Validation of an Internally-Lit Airlift Photobioreactor.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2010, Ohio University
► A novel photobioreactor for growing algae was developed from a previous Ohio…
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▼ A novel photobioreactor for growing algae was developed from a previous Ohio University patent. The proposed design uses the air lift principle to enhance the culture circulation and induce light/dark cycles to the microorganisms. Optical fibers were used to distribute photons inside the culture media providing an opportunity to control both light cycle and light intensity. The fibers were coupled to an artificial light source, however the development of this approach aims for the future use of natural light collected through parabolic solar collector. This idea could also allow the use of non-clear materials for photobioreactor construction diminishing costs and increasing durability. A 30-liter laboratory scale unit was designed and constructed using inexpensive plastic fiber optic cables. Materials were selected to assure fast constructability and maximize light use. As a research tool, the device should meet the criteria of removable, replaceable, and accessible for maintenance. All the pieces of the device were planned to be able to be removed and replaced by ones of alternative design, assuring flexibility for future researchers using or modifying the device. Internal light levels were determined in dry conditions and they were more than 80 µmol/(s•m2). The hydrodynamic equations of the air lift phenomena were explored and used to define the geometric characteristics of the unit. The reactor was inoculated with the algae strain Chlorella sp. and sparged with air. The reactor was operated under batch mode and daily monitored for pH, temperature, and biomass concentration and activity. The productivity of the novel device was determined, 0.011 h-1, suggesting the proposed design can be effectively and economically used in carbon dioxide mitigation technologies and in the production of algal biomass for biofuel and other bioproducts.
Advisors/Committee Members: Stuart, Ben.
Subjects: Aquaculture; Cellular biology; Energy; Engineering
Keywords: Algae, bioproducts, photobioreactors, biofuel
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14.
Hlebak, Joshua J.
Equilibrium Modeling, Design, Construction, and Validation Testing of a Pilot Scale, USS Gasification Reactor.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► Fluidized bed gasification is currently not economically feasible on small and medium…
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▼ Fluidized bed gasification is currently not economically feasible on small and medium scales due to the expensive catalytic reformation of tar. It has been proposed to thermally reform this tar with an ultra-superheated steam (USS) flame that would be injected through tuyeres located inside the fluidized bed. This research involved modeling, design, construction, and validation of a USS gasification reactor, without the USS tuyere injection system. Systems were designed and tested to create a syngas via an USS gasification reactor, oxidize the syngas via an incinerator, gather experimental data, and ensure safe operation. This process was verified in a preliminary validation test. The USS reactor was able to produce a low quality syngas, while oxidizing the hazardous species for safe exhaust. Also the safety and data acquisition systems operated according to design. The alumina, reactor cylinder fractured with high temperature entrained particulates escaping the system, which ceased any further testing.
Advisors/Committee Members: Bayless, David.
Subjects: Engineering
Keywords: USS; Gasification; Fluidized
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15.
Holzaepfel, Gregory M.
Convective Heat Transfer in Parallel Plate Heat Sinks.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► This research study explores the transition between developing and fully-developed flow to…
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▼ This research study explores the transition between developing and fully-developed flow to evaluate the heat transfer for single-phase convection in a parallel plate heat sink. A range of modified Reynolds number values between 14.0 and 44.8 was selected based upon pre-existing work to be representative of this transition region. The experimental results were found to be in reasonable agreement with the pre-existing model for high aspect ratio channels. Several numerical solutions for rectangular duct flow are also compared with the observed results. The experimental results for the Nusselt number were found to be within a maximum observed error of 16.5% of the published model for the transition between developing and fully-developed flow. This error exceeds the maximum standard deviation for the experimental results of 0.05. Reasons for differences between the current experimental results and the selected models are discussed.
Advisors/Committee Members: Alam, Khairul.
Subjects: Engineering; Mechanical Engineering
Keywords: Parallel Plate Heat Sink; Single-Phase Convection; Developing to Fully-Developed Flow Transition
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16.
Karadogan, Ernur.
A Cable-Actuated Robotic Lumbar Spine as the Haptic Interface for Palpatory Training of Medical Students.
Degree: PhD, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► The role of simulation in medical education is rapidly increasing. Simulations to…
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▼ The role of simulation in medical education is rapidly increasing. Simulations to train nurses, veterinarians and doctors (osteopathic and allopathic) are utilized due to their effectiveness and cost-reducing advantages. These simulations can be computer-based or in the form of mannequins that can simulate some functions of the real human body such as breathing, blood pressure, pulse and temperature, among others. Computer-based haptic simulations require the usage of a haptic interface to interact with virtual objects. That is clearly not the case when humans interact with real objects. Therefore, a system which allows the user to interact with a real object could be a more realistic and effective approach. This dissertation presents the theoretical framework (kinematics, pseudostatics, dynamics and control) of a novel 15 degree-of-freedom cable-actuated robotic lumbar spine (RLS) which can mimic in vivo human lumbar spine movements to provide better hands-on training for medical students. The design incorporates five active lumbar vertebrae and the sacrum, with dimensions of an average adult human spine. It is actuated by 20 cables connected to electric motors. Every vertebra is connected to the neighboring vertebrae by spherical joints. The RLS is designed to be controlled by a force-feedback joystick or an affordable haptic device. By moving the joystick, the angles of rotations are commanded to the RLS, therefore representing a normal lumbar spine movement. A static model of the human lumbar spine was also derived to obtain these normal movement patterns for different types of motion. Medical schools can benefit from a system that will help instructors train students and assess their palpatory proficiency throughout their education. The RLS has the potential to support these needs in palpatory diagnosis. Medical students will be given the opportunity to examine their own patient that can be programmed with a variety of dysfunctions related to the lumbar spine before they start their professional lives as doctors. The robotic lumbar spine can be used to teach and test medical students to be able to recognize normal and abnormal movement patterns of the human lumbar spine under flexion, extension, lateral bending and axial torsion.
Advisors/Committee Members: Williams, Robert.
Subjects: Biomechanics; Mechanical Engineering; Robotics
Keywords: Cable robot; human lumbar spine; Palpatory training; RLS; Robotic lumbar spine; three-dimensional static modeling
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17.
Kaseman, Brian J.
An Investigation of Secondary Formations of High Temperature Solid Oxide Fuel Cells.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2012, Ohio University
► Solid Oxide Fuel Cells (SOFCs) are aimed to operate using coal syngas…
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▼ Solid Oxide Fuel Cells (SOFCs) are aimed to operate using coal syngas but the gas may have a negative impact on the component materials. The gas contains impurities such as phosphorus could react with an anode component gadolinia doped ceria (GDC). Nextcells with a Ni-GDC interlayer were operated at 0.7V in coal syngas containing 10 and 20ppm PH3 at 800 and 900°C for 42 hours. The power density reduced by 92% at 800°C when exposed to both PH3 concentrations. Degradation was determined to be caused by ohmic, activation, and concentration polarizations. X ray diffraction (XRD) and X ray photoelectron spectroscopy (XPS) show the formation of CePO4. It is determined that phosphorus species are detrimental to the Ni-GDC interlayer in accelerated testing. Additionally, the main components of coal syngas (hydrogen, nitrogen, carbon monoxide, carbon dioxide, and steam) may form secondary phases with the silver (Ag) current collector. SOFCs with anode Ag current collectors were operated in coal syngas at 850°C for 100 hours. XRD did not detect any secondary formations of Ag. Coal syngas is not believed to have an affect on the Ag current collector. The migration of Ag through the scandia stabilized zirconia (ScSZ) electrolyte by electro- and thermomigration was also investigated. SOFCs were operated at 0.7V in H2 at 900°C for 200 hours to activate these migration mechanisms. Secondary Electron Microscope (SEM) showed Ag at the interface but elemental mapping did not detect Ag in the ScSZ electrolyte. It was found that Ag will not short circuit the SOFC in short term testing.
Advisors/Committee Members: Bayless, David.
Subjects: Engineering
Keywords: SOFC; Syngas; Phosphine; GDC; Ag; Migration
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18.
Kaufman, Brian A.
The Effect of Operational Voltage on a Solid Oxide Fuel Cell Operating on Coal Syngas Containing Trace Amounts of Phosphine.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► Electrolyte-supported Solid Oxide Fuel Cells have been proven capable of generating usable…
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▼ Electrolyte-supported Solid Oxide Fuel Cells have been proven capable of generating usable electricity when supplied with various fuels, including a synthetic fuel (syngas) generated from gasified coal. Coal, however, contains contaminants, namely phosphine (PH3), that remain in the syngas despite cleanup technologies, which can lead to lowered electrical performance caused by the formation of secondary compounds. This study investigates a strategy of varying the operational voltage to potentially mitigate the formation of secondary compounds, including nickel phosphide (NixPy), thus prolonging the life of the cell. Two operational voltage conditions were investigated, 0.7 volts and 0.6 volts, with four cells per voltage tested. The degradation of the cell was determined using electrical data generated as well as with material analysis. Post-mortem cells were analyzed for the presence of secondary formations with techniques including XRD, SEM/EDX, and XPS. The results indicate that the operational voltage has little effect on the formation of nickel phosphides and the prevailing nickel phosphide specie was Ni2P in both operational voltage conditions.
Advisors/Committee Members: Bayless, David.
Subjects: Engineering; Mechanical Engineering
Keywords: Solid Oxide Fuel Cell; operational voltage; phosphine; SOFC
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19.
Kohli, Dhruv.
Development and Validation of a NOx Emission Testing Setup for a Diesel Engine, Fueled with Bio-Diesel.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2009, Ohio University
► The increasing concerns related to long term availability of petroleum-based fuels and…
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▼ The increasing concerns related to long term availability of petroleum-based fuels and the emissions from diesel-powered vehicles have given rise to a growing search for an alternate source of fuels for use in diesel vehicles. One of the most recent and promising findings in this field is “Bio-diesel”. The thesis uses a comparative study of NOx emission characteristics for regular diesel fuel and soy based biodiesel for a four cylinder, 60 HP turbocharged diesel engine for validation of the engine and the emission test rig. Modifications are recommended for the current test setup and test procedure to enable research quality testing of Algae based biodiesel.
Advisors/Committee Members: Kremer, Gregory G.
Subjects: Mechanical engineering
Keywords: NOx Emission Testing; NOx Emission Testing Setup; Biodiesel comparison to diesel; NOx testing for Biodiesel
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20.
Kunapareddy, Naveen.
A Proof-of-Concept Test for Seperation Efficiency of an Electro-Cyclone.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2009, Ohio University
► This research is aimed at making coal gasification a more cost-competitive technology…
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▼ This research is aimed at making coal gasification a more cost-competitive technology by reducing the enormous costs associated with hot gas clean up. To achieve this an electrostatic cyclonic separator was designed, which is capable of concentrating particulate matter from very high temperature gas streams into small slip streams thus enabling the bulk gas to flow particulate free through the outlet.
Advisors/Committee Members: Kremer, Gregory.
Subjects: Engineering; Environmental engineering; Environmental science; Mechanical engineering
Keywords: Electro-Cyclone; Particulate Pollution Control; Electrostatic Precipitators
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21.
Laing, Jeffrey M.
Finite Element Modeling and Validation of a Novel Process for Extruding Thin Wall Hollow Copper Profiles.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2012, Ohio University
► The purpose of this research was to develop an approach to simulate…
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▼ The purpose of this research was to develop an approach to simulate a novel, high ratio extrusion process using finite element (FE) software. In order to accomplish this, several techniques were used. These include local mesh refinement, increasing the frequency of remeshing, increasing nodal relaxation and decreasing the duration of the time step. Three simulations were completed using progressively larger billets with the goal of determining the largest billet that could be extruded by a 250 kN, 400 ton or 1600 ton press. Simulation results for the 250 kN press were compared to experimental data from lab-scale testing. The extrusion force predicted was within 2% of the experimental value. Simulations of scaled-up processes, using 400 and 1600 ton presses, were compared to results of a basic extrusion-work calculation, with an uncertainty of 12%. The results of the FE analyses were within 10% of the calculated values and within the expected uncertainty.
Advisors/Committee Members: Kraft, Frank.
Subjects: Engineering; Mechanical Engineering
Keywords: Finite Element; Micro Channel Extrusion; Hollow Profile; High Extrusion Ratio; Multi Billet; Copper Extrusion
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22.
Litten, Jonathan D.
Development of an Automatically Adjustable Colonoscope.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► The focus of this thesis is the design and preliminary testing of…
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▼ The focus of this thesis is the design and preliminary testing of a unique device to improve colonoscopy screening methods. Conventional colonoscopy can often be associated with complications such as mechanical trauma to the colon and extended anesthesia use. To alleviate these problems, an automatically adjustable colonoscope was designed to automatically position the colonoscope tip in the center of the colon lumen. This device included three systems: A sensory system mounted at the tip of the colonoscope to determine the distance to the colon wall; an actuation system to turn the control knobs and move the distal tip; and a control system to integrate the functions of the sensory and actuation systems. Several tests were performed to determine the necessary parameters of each system, such as the relationship between sensor output voltage and distance sensed and the relationship between the actuator movement and the distal tip movement. Control logic based on a circular cross-section of the colon lumen was also developed. The device was tested in a colonoscopy training model and was shown to be able to navigate through passages of the colon.
Advisors/Committee Members: Choi, Dr. JungHun.
Subjects: Biomedical Engineering; Engineering; Mechanical Engineering
Keywords: Colonoscopy; Colonoscope; Automatic; Automatically Adjustable
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23.
Liu, Mu-Hsin.
Multiaxial Fatigue Testing Machine.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2002, Ohio University
Multiaxial Fatigue Testing Machine
Advisors/Committee Members: Pasic, Hajrudin.
Subjects: Mechanical engineering
Keywords: fatigue testing; multiaxial fatigue; fatigue
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24.
Liu, Mu-Hsin.
Multiaxial Fatigue Testing Machine.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2002, Ohio University
Multiaxial Fatigue Testing Machine
Advisors/Committee Members: Pasic, Hajrudin.
Subjects: Computer science; Electrical engineering
Keywords: fatigue; testing; multiaxial fatigue
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25.
Lunka, Alex A.
Effects of Flashing Light-Emitting Diodes in a Membrane-Based Photobioreactor.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2012, Ohio University
► A major problem associated with using photobioreactors for producing alga biofuels are…
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▼ A major problem associated with using photobioreactors for producing alga biofuels are the issues associated with scale. In order to help minimize power consumption for a bioreactor, the flashing light effect was explored by monitoring growth and power consumption in control experiments using constant light at 75µmol/m2-s and three flashing experiments with light intensities at 375µmol/m2-s, 275µmol/m2-s, and 175µmol/m2-s. Flashing experiments were performed at 10kHz and a duty cycle of 20%; the lights were on for 20% of the time during a flash cycle and off for the remaining 80%. Several unsuccessful attempts to test this light were made in a membrane based photobioreactor, but an unresolved problem prohibited algae from growing. Therefore, a sliver tank bioreactor with a chamber width of 1/4” was used to simulate the short optical path exhibited in the membrane bioreactor. The flashing experiments used 9.6% less power and produced 0.16g algal biomass, or 2.86 times as much as the constant control experiments. Similar results were obtained for the other flashing light regimes, which had lower biomass yields but also less input power per unit biomass produced.
Advisors/Committee Members: Bayless, David.
Subjects: Energy; Engineering; Environmental Engineering; Mechanical Engineering
Keywords: Scenedesmus sp.; Flashing Light Effect; Chroogloeocystis siderophila; Photobiroeactor; Turbidity; Photosynthesis; Light-Emitting Diodes
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26.
Mears, Benjamin M.
Design, Construction and Testing of Pilot Scale Photobioreactor Subsystems.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2008, Ohio University
► Methodology of designing and testing pilot scale photobioreactor containment and gas circulation…
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▼ Methodology of designing and testing pilot scale photobioreactor containment and gas circulation subsystems. Evaluation of containment subsystem seal surfaces basedon testing of bench-top model with identical features. Gas circulation subsystem evaluated based on airflow distribution profile generated from air velocity data taken from full size photobioreactor. Considerations and recommendations for subsystem integration into complete pilot scale facility.
Advisors/Committee Members: Stuart, Ben J.
Subjects: Mechanical engineering
Keywords: Photobioreactor; Carbon Sequestration; Algae
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27.
Murphy, Robert T.
Developing, Demonstrating, and Validating a Vehicle Test Bed to Extend the Capabilities of a Chassis Dynamometer Test System.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2008, Ohio University
► There was a need to study drive train components (such as transmissions)…
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▼ There was a need to study drive train components (such as transmissions) in the Mechanical Engineering Automotive lab at Ohio University. The approach was to expand the capabilities of the existing chassis dynamometer into a complete drive train test system. The prototype Electric Bobcat Racecar was modified to serve as a platform for component testing by removing all non-essential parts from the chassis. Suitable mounts were designed for the motor, controller, and cooling system. A wireless telemetry strain gage system was selected to measure shaft torque at locations throughout the drive train and on the dynamometer shaft. A gantry crane was selected to safely load components into the test bed and the test bed onto the roller frame.Validation testing confirmed that the strain gage telemetry system gave values consistent with the values recorded by the calibrated dynamometer. Differential testing confirmed the capability of single component testing. Testing of two strain gages on the same shaft confirmed the potential repeatability of strain gages to be used as torque sensors.
Advisors/Committee Members: Kremer, Gregory G.
Subjects: Mechanical engineering
Keywords: Chassis Dynamometer; Wireless Telemetry Strain Gage; Electric Bobcat; Vehicle Drive Train; Component Test Bed; Torque Distribution
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28.
Perera, Chaminda Kithsiri.
The Effects of Mercury on the Performance of Ni/YSZ Anode in a Planar Solid Oxide Fuel Cell.
Degree: PhD, Mechanical Engineering (Engineering and Technology), 2010, Ohio University
► This study was made to determine effects of mercury as a contaminant…
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▼ This study was made to determine effects of mercury as a contaminant in coal syngas on the performance of a Ni/YSZ anode of a planar solid oxide fuel cell (SOFC). Anode supported SOFCs were operated with Hg-contaminated fuel gas at two different temperatures and at two different gas compositions. Significant modifications to the testing system were made to reduce the effects of stagnation layers. A reliable method of mercury delivery to the cell was designed, calibrated, and implemented prior to testing. A novel technique of area specific resistance (ASR) calculation using electrochemical impedance spectroscopy (EIS) was used, coupled with standard electrochemical techniques. The novel EIS technique for ASR analysis provided a reliable and repeatable method for determining cell degradation. Post-experimental materials analyses using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to determine the effects of mercury on SOFC performance. Electrochemical analyses coupled with material analyses demonstrated that mercury at concentrations as high as 1000 ppb had no discernable effect on normal cell performance. A novel method is proposed for computing cell degradation rate based on cell ASR that is much less current dependent than the present voltage-based method. Recommendations for future work include methods to improve SOFC test systems to obtain more reliable data by removing uncertainties in operational conditions.
Advisors/Committee Members: Bayless, David.
Subjects: Chemical engineering; Energy; Engineering; Mechanical engineering
Keywords: SOFC; Coal Syngas; Contaminant; EIS; ASR; Energy
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29.
Pocztar, Yuri M.
Heat, Light, and Gas Composition Subsystems of a Photo-Bioreactor.
Degree: MS, Mechanical Engineering (Engineering and Technology), 2010, Ohio University
► Methodology of designing and testing an intermittent natural gas burner system to…
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▼ Methodology of designing and testing an intermittent natural gas burner system to be used in a pilot scale photobioreactor is presented. Safety shutoff systems, temperature distribution, and gas compositions based on mockup trial runs were evaluated. Artificial fiber optic light system assessed based on light readings generated from dark room testing. Considerations and recommendations for subsystems integration into complete pilot scale facility are offered for future research.
Advisors/Committee Members: Stuart, Benjamin.
Subjects: Engineering; Environmental Engineering; Mechanical Engineering; Optics
Keywords: Bioreactor; algae; carbon mitigation; fiber optics
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30.
Ramadan, Saleem Z.
Bayesian Multi-objective Design of Reliability Testing.
Degree: PhD, Mechanical Engineering (Engineering and Technology), 2011, Ohio University
► This dissertation proposed a method for designing optimal reliability testing plans for…
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▼ This dissertation proposed a method for designing optimal reliability testing plans for simple life test, accelerated life test, and simple step accelerated life test using the Bayesian approach and a multi-objective genetic algorithm. Two criteria, cost and prediction precision of the test, have been optimized simultaneously. The Bayesian approach was considered an attractive alternative to the traditional maximum likelihood method for minimizing uncertainty in the "planning values" of the model parameters. The multi-objective genetic algorithm was adopted to solve the planning problem and to produce a set of alternative plans from which a planner may choose the most desirable plan. In this dissertation, the effect of the priors and the cost structures on the optimal plans was studied to investigate how the optimal plans will response when different priors and cost structures are used. In addition, MLE and Bayesian approaches were compared to investigate the similarities and the differences between those methods. The statistical optimal plans were investigated to see the effect of the model constraints on the statistical optimal plans for accelerated life tests and for simple step accelerated life tests. This dissertation was based on Bayesian method and genetic algorithms, which are flexible methods, therefore the models proposed in this dissertation can be easily extended for future work to cover a larger spectrum of test structures, utility functions, life distributions, prior distributions, and cost structures.
Advisors/Committee Members: Yuan, Tao.
Subjects: Mechanical Engineering
Keywords: Reliability Testing; GA; Bayesian; MLE; ALT; Multi-objective; optimization
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