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.

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.

This thesis details the process of developing a force feedback system for a small robotic manipulator in order to prevent damage to manipulators and the objects they are grasping, which is a desired feature in many autonomous robots. This includes the research, design, fabrication, and testing of a custom force-sensing resistor and a custom set of jaws to implement the feedback system on. In order to complete this project, extensive research went to designing and building test beds for the commercial and custom force sensors to determine if force values could even be obtained. Then the sensors were implemented on a manipulator and were evaluated for ease of use during assembly and testing, accuracy, and repeatability of results using a test bed designed during the course of this research. Afterwards the custom jaws were designed and fabricated based on problems encountered during testing with the initial set of jaws. The new jaws were then tested on the test bed with the sensors and the force feedback system was implemented on it. The overall system was then evaluated for any current limitations and improvements that could be made in the future to further develop this research and assist with its implementation on other robots. The results of this experiment show that a low-cost force sensor that is easy to mass produce can be implemented on an autonomous robot to add force feedback capabilities to it. It is hopeful that the results from the experiments conducted are implemented on robotic manipulators so the area of force sensing technologies research can be expanded upon and improved.

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.

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.

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.

This paper presents an experimental investigation into the effects of altering electrode surface area roughness on thermogalvanic cell performance. A temperature difference between two electrodes was induced and brought to steady state to achieve a difference of around 50 °C, which was maintained with a DC power generated hot wire and a pumped ice bath. The open-circuit voltage values at steady-state were measured by a programed multimeter and the temperatures were measured by a series of type K thermocouples. Electrode surface area roughness was altered using different grit values of sandpaper and measuring the values using a Zescope Optical Profilometer. Once three different surface area average values were achieved, 6 trials were performed with 2 trials per roughness value. The results were tabulated in Section 4 of this report.
It was predicted that increasing the surface area roughness would increase the number of electrons present in the reduction oxidation reaction and decrease the activation resistance of the thermogalvanic system. Decreasing the activation resistance, a component of total internal resistance, would therefore increase the power output of the cell by a small magnitude. The results showed that changing the surface area roughness of the Copper electrodes evidently had no effect on the outputs of the cell system. Additionally, the Seebeck coefficient was also unaffected by the presence of increased surface area roughness.
The work presented in the following paper is part of a continuing effort to better understand the performance of thermogalvanic cells and their heat to electrical energy transfer properties.

TiO2 has been studied in the degradation of ethanol for indoor application. A dynamic flowing non-loop system was utilized. The reactor was a quartz tube filled with the TiO2 catalyst with glass wool on the ends. The analytical equipment used were Vernier's ethanol and CO2 sensors with a two-point calibration performed on the ethanol sensor. The purpose of the calibration was to create a known standard to establish accurate readings. The experimental procedure followed the scheme of bypassing the reactor, flowing into the reactor without the UV lights on for a small period, turning the UV lights on for five minutes, and then going back to the bypass. A CFD simulation using ANSYS Fluent was done to determine the optimal inlet and outlet positions of the biochamber that housed the sensors. The objective of the simulation was to determine which inlet and outlet locations provided the best fluid flow for sensor contact and mixing. Sensitivity analysis of varying parameters were tested to determine the optimal settings in producing accurate results to fulfill the simulation goals. It was determined that a vertical position biochamber with an inlet centered on the top face and the outlet on the bottom of a side face was ideal. The main experimental results showed that ethanol of both low and high concentrations were completely or almost fully degraded into carbon-products. The results showed that there was CO2 consumption and it was most likely due to a combination of sensor inaccuracy and accumulation onto the catalyst surface. However, the sensor inaccuracy would not account for the entirely of the CO2 consumption and previous studies have shown that carbon-products do form on the catalyst surface. Therefore, it can be asserted that CO2 has accumulated on the catalyst and the inclusion of water may have caused catalyst deactivation. Having the light on the photoreactor the whole time rather than waiting to turn on the light has shown to decrease the period of degradation but has no effect on the amount of degradation. Research from Nimlos, Muggli, etc., have determined that intermediate products such as acetaldehyde, acetic acid, formaldehyde, and formic acid form during ethanol degradation and this can be assumed to have occurred in this research as well. These intermediate products were not analyzed for this study, but has been included in the go-forward for future works. For indoor applications, TiO2 catalyst have already been implemented into consumer and commercialized air purifiers, but there is tremendous potential for HVAC systems. There are concerns with HVAC application as discussed, but if implemented correctly, it can be a useful tool for indoor air purification.

To determine the effects of exhaust heat recovery systems on small engines, an experiment was performed to measure the power losses of an engine with restricted exhaust flow. In cooperation with ASU's SAE Formula race team, a water brake dynamometer was refurbished and connected to the 2017 racecar engine. The engine was mounted with a diffuser disc exhaust to restrict flow, and a pressure sensor was installed in the O2 port to measure pressure under different restrictions. During testing, problems with the equipment prevented suitable from being generated. Using failure root cause analysis, the failure modes were identified and plans were made to resolve those issues. While no useful data was generated, the project successfully rebuilt a dynamometer for students to use for future engine research.

The main objective of this project was to continue research and development of a building integrated solar thermoelectric generator (BISTEG). BISTEG is a promising renewable energy technology that is capable of generating electrical energy from the heat of concentrated sunlight. In order to perform R&D, the performance of different TEG cells and TEG setups were tested and analyzed, proof-of-concepts and prototypes were built. and the performance of the proof-of-concepts and prototypes were tested and analyzed as well. In order to test different TEG cells and TEG setups, a TEG testing apparatus was designed and fabricated. The apparatus is capable of comparing the performance of TEGs with temperature differentials up to 200 degrees C. Along with a TEG testing apparatus, several proof-of-concepts and prototypes were completed. All of these were tested in order to determine the feasibility of the design. All three proof-of-concepts were only capable of producing a voltage output less than 300mV. The prototype, however, was capable of producing a max output voltage of 17 volts. Although the prototype outperformed all of the proof-of-concepts, optimizations to the design can continue to improve the output voltage. In order to do so, stacked TEG tests were performed. After performing the stacked TEG tests, it was determined that the use of stacked TEGs depended on the Fresnel lens chosen. If BISTEG were to use a point focused Fresnel lens, using a stack of TEGs could increase the power density. If BISTEG were to utilize a linear focused Fresnel lens, however, the TEGs should not be stacked. It would be more efficient to lay them out side by side. They can be stacked, however, if the energy density needs to be increased and the costs of the additional TEGs are not an issue.