Search

There is an increasing demand for individuals with engineering education and skills of varying fields in everyday life. With the proper education students of high-needs schools can help meet the demand for a highly skilled and educated workforce. Researchers have assumed the supply and demand has not been met within the engineering workforce as a result of students' collegiate educational experiences, which are impacted by experiences in K-12 education. Although factors outside of the classroom contribute to the inability of universities to meet the increasing demand for the engineering workforce, most noted by researchers is the academic unpreparedness of freshman engineering students. The unpreparedness of entering freshman engineering students is a result of K-12 classroom experiences. This draws attention not only to the quality and competence of teachers present in the K-12 classroom, but the type of engineering instruction these students are receiving. This paper was an effort to systematically address one of the more direct and immediate factors impacting freshman engineering candidates, the quality of secondary engineering educators. Engineers develop new ideas using the engineering design process, which is taught at the collegiate level, and has been argued to be the best approach to teach technological literacy to all K-12 students. However, it is of importance to investigate whether technology educators have the knowledge and understanding of engineering design, how to transfer that knowledge in the classroom to students through instructional strategies, and their perception of their ability to do that. Therefore, the purpose of this study is to show the need for examining the degree to which technology and non-technology educators are implementing elements of engineering design in the curriculum. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]

This paper introduces low-velocity impacts (LVI), presents a concept for evaluating them, tests various materials for proof-of-concept, and discusses how the machine could be used in future university projects as well as how it could be improved. The paper begins by defining low-velocity impacts and describing the factors that influence them. The second topic is the iterative design process involved with making an impact machine so that accurate results can be obtained. In the third section, some of the challenges and opportunities associated with the concept of low velocity impacts with a variety of tests conducted on the machine and with different materials. A summary of the design and results of the study is presented at the end of the paper, followed by some suggestions for further research and improvements that could be made.

Wirewalker vertical profilers have become a common tool for oceanographic research, but the energy required by onboard sensors sets up a maximum horizon for deployment before ongoing recovery and re-deployment becomes impractical and expensive. Given that the Wirewalker mechanically harnesses energy from ocean surface waves to drive propulsion, a natural next step for the Wirewalker system is using ocean wave energy to power the onboard sensors. This paper documents the design process for a 3-wheel power take-off system that merges the submersible motor-generator (Livewire), designed by Dr. Michael Goldin and Prof. Drew Lucas, within a Wirewalker frame. The as-tested “omega-configuration” power take-off relies on the grip of a single wheel on the mooring wire to both cam in one direction (allowing profiling mechanically driven by the surface waves, as in the present generation Wirewalker, and also efficiently generating power. Basic profiling dynamics and experimental results inspired a design that pushes the generator wheel between two sheaves, while allowing it to hinge up and down to passively increase grip on the wire as the power available in any particular wave cycle increases. Tests in the Scripps pool generated a peak power of 1 Watt, with a time average 0.1 Watts. However, this result was likely related to slipping and frictional losses, which also was observed to inhibit 1-way camming motion. Future iterations of the 3-wheel power take-off should wrap the wire further around the wheel, investigate wheel surfaces with a higher coefficient of friction, and reduce internal friction losses with better constrained sheaves.

APEX, Alternative Perspective for the User Experience, is a two-year collaboration between Ohio State University, ArtCenter College of Design, and Honda R&D Americas, Inc. The purpose of this project was to determine the millennial vision of the future of mobility. Honda tasked student teams at ArtCenter and OSU to design the user experience of an autonomous vehicle interior for millennial women in 2030. The final output of the project was a full-scale functional interior prototype. Honda will validate user experience concepts from this project with millennial women to ensure the APEX experience meets target customer needs and to guide future research.Out of the six project phases, OSU led the latter three which involved the design, implementation, and validation of the high-level interior prototype. The OSU team utilized principles of design thinking and lean startup, as well as project frameworks such as scrum and the V-model, throughout the project. This paper discusses the design, implementation, and testing of the APEX autonomous vehicle interior prototype. The paper will especially focus on management of the resources and technical partners involved in the project, and the integration of the vehicle subsystems into a functioning prototype.

Advancements in semiconductor technology present new challenges in electric machine construction, operation, and control. Silicon carbide (SiC)-based power electronics are becoming the new standard for high-power consumer and commercial devices, and are implemented in technologies such as power inverters, converters and rectifiers. This paper focuses on the effects of inverter drives for traction motors in electric vehicles with high dV/dt rates on bar-wound machine windings, including the expected impacts on insulation materials under prolonged periods of high voltage stress. Partial discharge inception voltage testing was performed to evaluate the voltage bus level at which breakdown will start to occur. A simulation model was constructed using finite element analysis, the results of which were validated with experimental results using a commercially available SiC inverter and traction motor. Correlation has been established between the preliminary simulation results and experimental data. It is proven that as DC bus voltages increase with the capabilities of SiC devices, the voltage stresses inside the stator windings approach levels which could cause partial discharge and premature insulation degradation in existing stator designs.

This dissertation proposes a multi-level optimization method for slender structures such as blades or towers of wind turbine structures. This method is suited performing structural optimizations of slender structures with a large number of design variables (DVs). The proposed method uses a two-level optimization process: a high-level for a global optimization of a structure and a low-level for optimizations of sectioned computational stations of the structure. The high-level optimization uses approximating functions to define target structural properties along the length of a structure, such as stiffness. The approximating functions are functions of the distance from the root of the structure that are defined using basis functions such as polynomials or exponential functions. The high-level DVs are the coefficients of the functions. Thus, the number of the high-level DVs is independent of the number of sections. Moreover, selecting smooth approximating functions help to obtain alternative designs with smooth shapes.The low-level optimization finds an optimum parametric design, such as laminate layups, that matches with the target structural properties defined at the high-level optimization. At the low-level optimization, the proposed method uses an optimizer in each section. Each optimizer is independent of the optimizers in the other sections, thereby decomposing a large optimization problem into several small ones. This approach reduces the number of DVs per optimizer at the low-level optimization which reduces the design space of each section and eliminates the design space of coupling between sections. Once optimum designs are found from all sections at the low-level, the high-level solvers evaluate them for the entire structure.The advantage of the proposed method is that it reduces the number of iterations of the high-level optimization because it considers a small number of high-level DVs. Computational efficiency increases because the computationally extensive high-level solvers need to be run less frequently to obtain an optimum solution. An additional advantage of the proposed method is that it produces many feasible alternatives.Using example problems, the paper demonstrates that the proposed method converges faster in the early iterations, and generates more alternative designs with smooth geometry than traditional single-level methods.