Matching Items (479)
Description
Graphene is a very strong two-dimensional material with a lot of potential applications in microelectromechanical systems (MEMS). In this research, graphene is being optimized for use in a 5 m x 5 m graphene resonator. To work properly, this graphene resonator must have a uniform strain across all manufactured devices. To reduce strain induced in graphene sheets grown for use in these resonators, evaporated platinum has been used in this investigation due to its relatively lower surface roughness compared to copper films. The final goal is to have the layer of ultrathin platinum (<=200 nm) deposited on the MEMS graphene resonator and used to grow graphene directly onto the devices to remove the manual transfer step due to its inscalability. After growth, graphene is coated with polymer and the platinum is then etched. This investigation concentrated on the transfer process of graphene onto Si/SiO2 substrate from the platinum films. It was determined that the ideal platinum etchant was aqua regia at a volumetric ratio of 6:3:1 (H2O:HCl:HNO3). This concentration was dilute enough to preserve the polymer and graphene layer, but strong enough to etch within a day. Type and thickness of polymer support layers were also investigated. PMMA at a thickness of 200 nm was ideal because it was easy to remove with acetone and strong enough to support the graphene during the etch process. A reference growth recipe was used in this investigation, but now that the transfer has been demonstrated, growth can be optimized for even thinner films.
ContributorsCayll, David Richard (Author) / Tongay, Sefaattin (Thesis director) / Lee, Hyunglae (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
It is a common assumption in the bicycle industry that stiffer frames generally perform better than flexible frames, because they transfer power more efficiently and absorb less energy from the rider's pedal stroke in the form of spring potential energy. However, in the last few years, Jan Heine of Bicycle Quarterly has developed an alternative theory, which he calls "planing", whereby a flexible frame can improve rider performance by not resisting the leg muscles as much, preventing premature muscle fatigue and allowing the rider to actually produce more consistent power, an effect which overwhelms any difference in power transfer between the different stiffness levels of frames. I performed several tests in which I measured the power input to the bicycle through the crankset and power output through a power-measuring trainer in the place of the rear hub. Heart rate data was collected along with most of these tests. Four bicycles were used with three distinct levels of stiffness. After performing several ANOVA tests to determine the effect of stiffness on the parameters of average power output during a sprint, maximum power output during a sprint, maximum heart rate during a sprint, difference between power-in and power-out during both sprints and longer efforts, and power quotient during a sprint, I found no effects of frame stiffness on any of these factors except power quotient. The finding for power quotient suggests a positive relationship between quotient and stiffness, which directly refutes the Planing Theory for the test riders and levels of stiffness represented in this test. Also, no statistically significant effect of stiffness on the difference between power-in and power-out was found, refuting the Power Transfer Theory for the riders and levels of stiffness represented in this test.
ContributorsSparks, Graham Philip (Author) / Takahashi, Timothy (Thesis director) / Middleton, James (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
This thesis document outlines the construction of a device for preparation of cylindrical ice-aluminum specimens. These specimens are for testing in a uniaxial load cell with the goal of determining properties of the ice-metal interface, as part of research into spray ice material properties and how such ice might be better removed from maritime vessels operating in sub-freezing temperatures. The design of the sample preparation device is outlined, justifications for design and component choices given and discussion of the design process and how problems which arose were tackled are included. Water is piped into the device through the freezers lid and sprayed by a full cone misting nozzle onto an aluminum sample rod. The sample rod is supported with Ultra High Molecular Weight Polyethylene pillars which allow for free rotation. A motor, timing belt and pulley assembly is used to rotate this metal rod at 1.25 RPM. The final device produces samples though intermittent flow in a 5 minutes on, 20 minutes off cycle. This intermittent flow is controlled through the use of a solenoid valve which is wired into the compressor. When the thermostat detects that the freezer is too warm, the compressor kicks on and the flow of water is stopped. Additional modifications to the freezer unit include the addition of a fan to cool the compressor during device operation. Recommendations are provided towards the end of the thesis, including suggestions to change the device to allow for constant flow and that deionized water be used instead of tap water due to hard water concerns.
ContributorsBaker, Dylan Paul (Author) / Oswald, Jay (Thesis director) / Yekani Fard, Masoud (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The purpose of this project was to construct and write code for an Internet-of-Things (IoT) based smart pet feeder to promote owner involvement in the health of their pets through the Internet to combat the high rate of obesity in pets in the United States. To achieve this, a pet feeder was developed to track the weight of the pet as well as how much food the pet eats while allowing the owner to see video of their pet eating, all through the owner's smartphone. In this thesis, current pet feeder strengths and weaknesses were researched, pet owners were surveyed, prototype features were decided upon, physical prototype components were purchased, a physical model of the pet feeder was developed in SolidWorks, a prototype was manufactured, and existing IoT libraries were utilized to develop code.
ContributorsCoote, Gabriela Phyllis (Author) / Ren, Fengbo (Thesis director) / Shrivastava, Aviral (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
In recent years, environment mapping has garnered significant interest in both industrial and academic settings as a viable means of generating comprehensive virtual models of the physical world. These maps are created using simultaneous localization and mapping (SLAM) algorithms that combine depth contours with visual imaging information to create rich, layered point clouds. Given the recent advances in virtual reality technology, these generated point clouds can be imported onto the Oculus Rift or similar headset for virtual reality implementation. This project deals with the robotic implementation of RGB-D SLAM algorithms on mobile ground robots to generate complete point clouds that can be processed off-line and imported into virtual reality engines for viewing in the Oculus Rift. This project uses a ground robot along with a Kinect sensor to collect RGB-D data of the surrounding environment to build point cloud maps using SLAM software. These point clouds are then exported as object or polygon files for post-processing in software engines such as Meshlab or Unity. The point clouds generated from the SLAM software can be viewed in the Oculus Rift as is. However, these maps are mainly empty space and can be further optimized for virtual viewing. Additional techniques such as meshing and texture meshing were implemented on the raw point cloud maps and tested on the Oculus Rift. The aim of this project was to increase the potential applications for virtual reality by taking a robotic mapping approach to virtual reality environment development. This project was successful in achieving its objective. The following report details the processes used in developing a remotely-controlled robotic platform that can scan its environment and generate viable point cloud maps. These maps are then processed off line and ported into virtual reality software for viewing through the Oculus Rift.
ContributorsUdupa, Shreya (Author) / Artemiadis, Panagiotis (Thesis director) / Chickamenahalli, Shamala (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Economics Program in CLAS (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This experiment used hotwire anemometry to examine the von Kármán vortex street and how different surface conditions affect the wake profile of circular airfoils, or bluff bodies. Specifically, this experiment investigated how the various surface conditions affected the shedding frequency and Strouhal Number of the vortex street as Reynolds Number is increased. The cylinders tested varied diameter, surface finish, and wire wrapping. Larger diameters corresponded with lower shedding frequencies, rougher surfaces decreased Strouhal Number, and the addition of thick wires to the surface of the cylinder completely disrupted the vortex shedding to the point where there was almost no dominant shedding frequency. For the smallest diameter cylinder tested, secondary dominant frequencies were observed, suggesting harmonics.
ContributorsCoote, Peter John (Author) / Takahashi, Timothy (Thesis director) / White, Daniel (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Walking ability is a complex process that is essential to humans, critical for performing a range of everyday tasks and enables a healthy, independent lifestyle. Human gait has evolved to be robust, adapting to a wide range of external stimuli, including variable walking surface compliance. Unfortunately, many people suffer from impaired gait as a result of conditions such as stroke. For these individuals, recovering their gait is a priority and a challenge. The ASU Variable Stiffness Treadmill (VST) is a device that is able to the change its surface compliance through its unique variable stiffness mechanism. By doing this, the VST can be used to investigate gait and has potential as a rehabilitation tool. The objective of this research is to design a variable damping mechanism for the VST, which addresses the need to control effective surface damping, the only form of mechanical impedance that the VST does not currently control. Thus, this project will contribute toward the development of the Variable Impedance Treadmill (VIT), which will encompass a wider range of variable surface compliance and enable all forms of impedance to be con- trolled for the first time. To achieve this, the final design of the mechanism will employ eddy current damping using several permanent magnets mounted to the treadmill and a large copper plate stationed on the ground. Variable damping is obtained by using lead screw mechanisms to remove magnets from acting on the copper plate, which effectively eliminates their effect on damping and changes the overall treadmill surface damping. Results from experimentation validate the mechanism's ability to provide variable damping to the VST. A model for effective surface damping is generated based on open-loop characterization experiments and is generalized for future experimental setups. Overall, this project progresses to the development of the VIT and has potential applications in walking surface simulation, gait investigation, and robot-assisted rehabilitation technology.
ContributorsFou, Linda Guo (Author) / Artemiadis, Panagiotis (Thesis director) / Lee, Hyunglae (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The emergence of the space industry facilitated new technologies which completely changed how humans live. However, the industry itself has also acted as a constant source of conflict between its participants. As a result, the industry has encountered issues regarding the role of private industry in space development, the militarization of space, how to address the gap in space technology between developed and underdeveloped nations, and the overall economic climate of space. With these numerous challenges facing the space industry, this investigation hopes to present potential solutions to said issues while providing a baseline for future research. In order to accomplish this, the international relations ideologies of neorealism, neoliberalism and constructivism were applied in conjunction with opinions from multiple industry scholars to synthesize potential solutions and provide a knowledge baseline and methodology for future investigations. This resulted in the conclusion that, in the scope of this investigation, a constructivist solution focusing on human nature's role in international relations is the best means of avoiding global conflict while promoting prosperity. The proposed constructivist solution proposes the development of multi-actor groups which defend, maintain and develop space assets collectively. These groups formed around ideological similarities would effectively limit conflict and increase the viability of space. However, this constructivist approach is not satisfactory due to its complexity which could result in the breakdown of peace and prosperity if interdependence between actors cannot be maintained. As a result, more research is necessary to develop an appropriate solution but, the methodology, information and understanding of different international relations principles used in this thesis can be used in future investigations to develop more comprehensive solutions.
ContributorsDeininger, Nicholas Robert (Author) / Foy, Joseph P. (Thesis director) / White, Daniel (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Pseudo-steady state (PSS) flow is a dominant time-dependent flow regime during constant rate production from a closed reservoir. Using Chen's (2016) exact analytical solution for the PSS flow of a fully-penetrated fractured vertical well with finite conductivity in an elliptical drainage area, the computational time required to solve for the PSS constant b_D,PSS is greatly reduced. This constant is the inverse of the productivity index, J_D,PSS, which is often used in modern fracture design optimization. This paper correlates the PSS flow of a fully-penetrated fractured vertical well in triangular drainage areas to Chen's solution for an elliptical drainage area using shape factors. Numerical solutions for the PSS constant are created using COMSOL, which uses a 2D model of the fractured reservoir to output time and pressure data. For equivalent reservoir properties, the numerical data for the triangular reservoir yields a PSS constant that can be directly compared to the PSS constant obtained using Chen's solution. Lack of access to the Subsurface Flow Module of COMSOL greatly limited the number of simulations that could be run, thus more simulations would significantly improve the accuracy and applicability of the triangular shape factor by making it a function of the penetration ratio through nonlinear regression methods.
ContributorsLight, Christopher Ting-Yu (Author) / Chen, Kangping (Thesis director) / Liao, Yabin (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The goal of this honors thesis creative project was to design, manufacture and test a retrofitted E-bike kit that met certain stated design objections. To design a successful E-bike kit, the needs of the customer were researched and turned into measurable engineering requirements. For the biker, these requirements are speed, range, cost and simplicity. The approach is outlined similarly to the capstone program here at ASU. There is an introduction in sections 1 and 2 which gives the motivation and an overview of the project done. In section 3, the voice of the customer is discussed and converted into requirements. In sections 4, 5,6,7 and 8 the design process is described. Section 4 is the conceptual design where multiple concepts are narrowed down to one design. Section 5 is the preliminary design, where the design parts are specified and optimized to fit requirements. Section 6 is fabrication and assembly which gives details into how the product was manufactured and built. Sections 7 and 8 are the testing and validation sections where tests were carried out to verify that the requirements were met. Sections 9 and 10 were part of the conclusion in which recommendations and the project conclusions are depicted. In general, I produced a successful prototype. Each phase of the design came with its own issues and solutions but in the end a functioning bike was delivered. There were a few design options considered before selecting the final design. The rear-drive friction design was selected based on its price, simplicity and performance. The design was optimized in the preliminary design phase and items were purchased. The purchased items were either placed on the bike directly or had to be manufactured in some way. Once the assembly was completed, testing and validation took place to verify that the design met the requirements. Unfortunately, the prototype did not meet all the requirements. The E-bike had a maximum speed of 14.86 mph and a range of 12.75 miles which were below the performance requirements of 15 mph and 15 miles. The cost was $41.67 over the goal of $300 although the total costs remained under budget. At the end of the project, I delivered a functioning E-bike retrofitting kit on the day of the defense. While it did not meet the requirements fully, there was much room for improvement and optimization within the design.
ContributorsLangerman, Jonathon Henry (Author) / Phelan, Patrick (Thesis director) / Trimble, Steven (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05