Matching Items (222)
Description
Waste plastic is considered an environmental pollutant because it is not biodegradable. Therefore, there is increased interest in the use of recycled plastic in pavement construction. Polyethylene terephthalate (PET) is a thermoplastic polymer that is commonly used in the manufacturing of containers and bottles. Waste PET is a durable material that has shown enhancement in performance when introduced into asphalt binder and asphalt mixtures. However, PET particles tend to separate from asphalt because of differences in density, molecular structure, molecular weight, and viscosity, leading to inadequate dispersion of PET particles in the asphalt. This incompatibility between PET and asphalt causes segregation, where storage stability becomes an issue. To solve this problem, applying a surface activation on the PET using another abundant urban waste (waste vegetable oil) was examined in this study, showing this method can be effective to enhance PET-asphalt interactions and consequently the storage stability of PET-modified asphalt. To ensure proper surface activation, it is important to thoroughly understand the chemo-mechanics of asphalt containing PET particles as well as the underlying interaction mechanism at the molecular level. Therefore, this study integrates a multi-scale approach using computational modeling based on density functional theory along with laboratory experiments to provide an in-depth understanding of the mechanisms of interaction between surface-activated PET and asphalt. To do so, the efficacy of bio-oil treatment was examined in terms of both the surface-activation capability and the durability of the resulting PET-modified asphalt. It was found that the grafted bio-oil on the PET particles can make a strong interaction with bituminous composites, leading to enhancing the durability and extending the service life of asphalt pavement by reducing the diffusion of free radicals and moisture into the bulk. The study was further extended to study the effect of coating the PET with biochar, showing the latter coating can improve the mechanical properties of the PET-modified asphalt and the adsorption behavior of the PET for volatile organic compounds. The performance of the waste PET was compared with another widely used modifier, crumb rubber.
ContributorsAldagari, Sand (Author) / Fini, Elham (Thesis advisor) / Kaloush, Kamil (Committee member) / Ozer, Hasan (Committee member) / Arizona State University (Publisher)
Created2024
Description
This thesis presents an overview of virtual reality (VR)-based teleoperation and describes its benefits and several existing challenges to its implementation, as well as potential solutions to these challenges. VR-based teleoperation of robotic arms enables a user to control and maneuver the robotic system from a remote distance while immersed in a virtual environment that simulates the location site of the robot. By implementing VR-based teleoperation, we can send robotic arms operated by trained professionals into harsh and inaccessible environments, including the deep sea and outer space, to accomplish manipulation tasks that would otherwise be unsafe or impossible. Teleoperated robotic arms can also be used to remotely execute fine manipulation tasks such as surgery, for instance, to reduce contamination or to perform operations in places that lack the required medical services.
In order to be able to reliably and comfortably use VR-based teleoperation, we need to focus on solving the challenges of latency and sensory loss. Since the teleoperator has a limited field of view and cannot rely on certain types of sensory information, they can feel disoriented and disconnected from the environment and robotic arm. Sensory information loss can be mitigated by simulating a wider field of view in the virtual environment, implementing additional sensors such as thermometers and gas detection sensors, and using data sonification techniques. Although it may not be possible to completely eliminate latency, the effects of latency can be reduced through the use of assistive interfaces that predict the trajectory of the robotic arm in real-time based on the teleoperator’s input movement using artificial intelligence (AI)-based predictive models. When visualized in the virtual environment, this predictive real-time feedback enables the user to immediately see the effects of their movements on the robotic arm, even though the arm’s actual motion is delayed due to latency, and thus avoid collisions and improve task performance. VR-based teleoperation can be enhanced with these proposed solutions to enable the user to complete the required manipulation task with high precision and to maneuver the robotic arm with reduced cognitive load.
ContributorsTrejo, Patricia (Author) / Berman, Spring (Thesis director) / Lee, Hyunglae (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2024-05