Mitigating the piston effect in high-speed hyperloop transportation: A study on the use of aerofoils

The Hyperloop is a concept for the high-speed ground transportation of passengers traveling in pods at transonic speeds in a partially evacuated tube. It consists of a low-pressure tube with capsules traveling at both low and high speeds throughout the length of the tube. When a high-speed system travels through a low-pressure tube with a constrained diameter such as in the case of the Hyperloop, it becomes an aerodynamically challenging problem. Airflow tends to get choked at the constrained areas around the pod, creating a high-pressure region at the front of the pod, a phenomenon referred to as the “piston effect.” Papers exploring potential solutions for the piston effect are scarce. In this study, using the Reynolds-Average Navier–Stokes (RANS) technique for three-dimensional computational analysis, the aerodynamic performance of a Hyperloop pod inside a vacuum tube is studied. Further, aerofoil-shaped fins are added to the aeroshell as a potential way to mitigate the piston effect. The results show that the addition of fins helps in reducing the drag and eddy currents while providing a positive lift to the pod. Further, these fins are found to be effective in reducing the pressure build-up at the front of the pod

Design and Characterization of a Single Lever Bicycle Brake with Hydraulic Pressure Proportioning

Featured Application: The work described here aims to design and characterize a more efficient bicycle braking system. In 2019, the Centers for Disease Control and Prevention estimated that 329,000 Americans were injured in cycling-related incidents. Since the first bicycle brake in 1817, there has been an individual brake lever for decelerating each wheel, while on cars, there has been a single control lever for decelerating multiple wheels since 1921. To perform an emergency stop on a bicycle, the rider must proportion hand pressure on each brake lever and simultaneously vary hand pressure throughout the duration of the maneuver to match the variations of normal force on each tire. Only highly skilled riders, with years of training and practice, can correctly proportion brake pressure to maximize available traction and thus minimize stopping distances. The objective of this study is to simulate and prototype a hydraulic, single-lever bicycle brake system, integrating front and rear brake proportioning, which minimizes stopping distance compared to dual-lever simulations. A design is developed to address the brake proportioning issue. Based on the simulations and physical model, the prototype proportioning valve decreased simulated stopping distances up to 18%. Exploring a range of bike types and scenarios, stopping distances were decreased between 13% and 26%. Simulating an ideal proportioning valve, stopping distances were further decreased between 4% and 40%. These results show that there can be an advantage to brake proportioning technologies in bicycles

Fused Deposition Modeling with Induced Vibrations: A Study on the Mechanical Characteristics of Printed Parts

The recent development of RepRap style 3D printers has made additive manufacturing technology available to the public at a low cost. While these 3D printers are being used for a variety of purposes, one of the main applications is prototyping in design projects. The quality of the 3D-printed parts has been a concern in such cases. Many variables within these printers’ operation can be varied to obtain optimum print quality. This study explores a setup that uses externally induced mechanical vibrations to the nozzle tip as a potential method to improve the quality of 3D-printed parts. Induced vibration is expected to decrease the porosity of printed parts and enhance the cohesion between print beads, ultimately improving their mechanical properties. The objective is to understand the prints’ positional accuracy, porosity, and mechanical properties with the added vibration and then to determine the optimum vibration level to achieve the best quality prints. While previous studies have explored the role of induced vibration on the mechanical properties of printed parts, the novelty of this work lies in the determination of the positional accuracy of those parts and the determination of optimum vibration levels to achieve desired properties. For positional accuracy, the extruder filament is replaced with a pointed-tip pen that can mark the exact location where the printer delivers the material. A comparison between the locations marked by the pen with and without vibrations shows that the errors induced by the added vibration are not significantly different from those caused by the uncertainties of the printer itself. Based on the tensile tests of the printed specimens, it is concluded that the parts printed with induced vibrations have improved mechanical properties. The printed parts’ porosity is reduced significantly due to the induced vibrations. Further, this study also explores the optimum motor speeds to achieve a uniform distribution of material. It determines medium motor speeds that provide a maximum vibration amplitude, which is more desirable for a consistent infill

Cognitive Effects of Physical Models in Engineering Idea Generation

Designers use various representations to externalize their ideas, physical models being an important one. Physical models are widely used by designers and their use is promoted as an effective design tool by industry and government agencies. However, very little is known about the cognitive effects of physical models in the design process; the available guidelines are conflicting. Some researchers argue for the frequent implementation of physical models, while others observe that the use of physical models fixates designers. In light of these conflicts, the research discussed in this dissertation focuses on understanding the cognitive effects of physical models and developing guidelines for aiding designers in their implementation. A combination of controlled lab studies and qualitative studies is adopted to achieve said goal. The results from the controlled studies show that physical models supplement designers’ erroneous mental models and help them to come up with more ideas satisfying the problem requirements. These studies also demonstrate that design fixation is not inherent in physical modeling, but it is caused by the Sunk Cost Effect. According to Sunk Cost Effect, as designers spend more time building physical models of their initial ideas, they tend to fixate more to the variations of those ideas. A qualitative study on industry-sponsored projects and development cases of award-winning products further supports these results in more realistic situations. Further, the studies reported in this dissertation show that physical models can be effective tools for the mitigation of fixation to undesirable design features in a flawed example; however, these results can also depend upon the experience level of a designer in solving open-ended design problems. With these insights from the series of studies, a set of guidelines and a Model Error Reeducation Method (MERM) are formulated and tested with novice designers. MERM helps designers in identifying critical loads and interface designs they miss in their original designs, before prototyping. The results from the testing of this method show that this method is very useful in avoiding said errors in physical modeling

Effects of Representations in Engineering Idea Generation Process

In today’s competitive market, it is essential to be innovative and creative for an industry to sustain. Industry need to introduce new products to the market. Engineering idea generation plays a vital role in the development of new products. This research study is focused on the engineering idea generation. The representations of ideas have an important impact on the idea generation process. Design concepts may be represented in a variety of forms like sketches, physical models or computer based models. The goal of this research is to understand how these various representations affect design cognition. In this thesis, three studies showing the effects of two different representations in the idea generation process are presented. The first study focuses on the effects of physical models in engineers’ design cognition. This preliminary study investigates two different hypotheses: (1) Physical models supplement and improve designer’s mental models and (2) Physical models induce design fixation. The results show that physical models supplement the designer’s mental models but fail to enhance them. No evidence of design fixation is observed. The second and third studies investigate the effects of computer-based idea generation software on design cognition. The research questions investigated in this study are: (1) How does the use of this software tool assist design cognition? (2) How can the software interface be improved so that designers can generate ideas more easily? To answer these questions, a between-subjects idea generation experiment is conducted. In the experiment, the participants are asked to generate ideas to solve a design problem with and without the software. The results show that participants who generated ideas with the help of the software tool have less quantity of ideas compared to the control group. This may be due to the design fixation induced by the concepts presented. In the third study, the opinions of the participants for the improvements of the software interface are collected. Results show that participants do not have any preference of one way of clustering the concepts over the other. The results of this study also provide creative input for the future improvement of the software

Evaluation of a puzzle-based virtual platform for improving spatial visualization skills in engineering freshmen

Being able to spatially visualize and mentally rotate is a key skill necessary to succeed in graphics and subsequent engineering courses. Recent research has focused on methods to develop Spatial Visualization (SV) skills in engineering students, as it is a key skill to succeed in most of the STEM fields. However, in most of the engineering schools, the instructors find it very difficult to develop keen SV skills in students. The major factors contributing to this challenge include, but not limited to the huge class sizes, limited time to teach the material, lack of effective demonstrations and the unavailability of feasible hands-on activities. With the funding from the National Science Foundation, the authors are developing a puzzle-based active learning platform called Student Assistant for Visualization in Engineering (SAVE) for developing SV skills in engineering freshman. In the preliminary version of this learning platform, the students are asked to complete a quiz with tasks requiring SV skills. For any incorrect answer, they are provided with automated hints about their mistakes. These hints are expected to help them in solving the following tasks. If they commit three mistakes, the quiz locks itself and creates a report on their performance thus far. The students are able to go back and restart the quiz. The student\u27s target is to complete the quiz with a minimum number of attempts. In the study reported here, the effectiveness of this game platform in conveying essential concepts of engineering graphics is investigated. Firstly, SAVE is implemented in a smaller classroom and the student feedback is collected. Then, it is implemented in a freshmen graphics class in a large public university in the west coast. The performance of the participating students in a follow-up exam is compared against that of a control group. The results show that the use of SAVE improves students\u27 conceptual understanding compared to a control group, as measured by the scores in the follow-up exam

Getting Fit in a Sustainable Way: Design and Optimization of a Low-Cost Regenerative Exercise Bicycle

With the increase in demand for more sustainable energy sources, recent researchers have been looking into harvesting energy spent by humans for various purposes. One of the available sources of such energy is exercise equipment. While a few products are available in the market to harvest the power expended during an exercise session, these products are costly, and the cost may prohibit a day-to-day user from purchasing those. Motivated by this challenge, this paper describes a long-running research project that uses a static exercise bicycle to sustainably harvest human energy. A regenerative spin bike that uses the friction between a flywheel and a BaneBots wheel was designed and deployed. For the motor mount, two methods are investigated: linear preloading and rotary preloading. A commercially available indoor static bicycle is modified to incorporate the flywheel and the motor attachment. The generated electricity is converted to DC using a three-phase rectifier. A car charger is used for charging any devices attached to the setup. The resulting configuration is very effective in operating small electronic devices. This setup, which uses only off-theshelf components, can be considered a replacement for its expensive custom-made counterparts

Mechanix: An Intelligent Web Interface for Automatic Grading of Sketched Free-Body Diagrams

Sketching free body diagrams is an essential skill that students learn in introductory physics and engineering classes; however, university class sizes are growing and often have hundreds of students in a single class. This situation creates a grading challenge for instructors as there is simply not enough time nor resources to provide adequate feedback on every problem. We have developed a web-based application called Mechanix to provide automated real-time feedback on hand-drawn free body diagrams for students. The system is driven by novel sketch recognition algorithms developed for recognizing and comparing trusses, general shapes, and arrows in diagrams. We have discovered students perform as well as paper homework or other online homework systems which only check the final answer through deployment to five universities with 450 students completing homework on the system over the 2018 and 2019 school years. Mechanix has reduced the amount of manual grading required for instructors in those courses while ensuring students can correctly draw the free body diagram

Sketchtivity, an Intelligent Tutoring Software: Broadening Applications and Impact

Freehand sketching is an essential skill for engineers. Sketching enables designers to represent ideas rapidly and offload working memory. Sketches in the design process also correlate with positive design outcomes. Teaching sketching to engineers, however, presents many challenges in engineering curriculums. Sketching is most often taught in large entry-level courses where individualized feedback, which is vital to learning sketching, is not possible. Sketchtivity is an intelligent tutoring software designed to aid in the practice and feedback on freehand sketching skills. Sketchtivity teaches the basics of two-point perspective sketching providing lessons, feedback, and tips on how to improve. The goal of this project is to implement Sketchtivity at a broader range of universities, to expand on the software functionality, and to understand more about the implications of improving sketching skill. Sketchtivity is currently being implemented in classrooms at three diverse universities across the United States. Our research has shown that the tablet interface does not negatively impact students’ sketching skill development. We are currently conducting further experiments to better understand how students are learning from the feedback the software provides. Beyond measuring current impact, this project seeks to expand the functionality of Sketchtivity to offer lessons on more complex sketching tasks and more poignant feedback to learners. The main research goal is focused on improving sketching skills. The remaining goals turn outward toward the implications for improved sketching skill for engineers. It is essential to understand how to measure sketching skill effectively, and what role sketching skill plays in engineering design. Sketching skill has been measured in many different ways in many different fields and there seems to be no consensus on measurement strategy or validity. As a part of this project, we are conducting a systematic literature review of sketching evaluation. This literature review aims to compile the different methods of measurement to remove some of the ambiguity around evaluating sketching skill in engineering research and education. There has been much research on the role of sketching in engineering design, but the research around sketching skill has been limited. Essential to improving skill in any task is understanding how confidence in the skill is affected. Engineers’ self-efficacy can enable or limit their application of skills. We are also looking at how sketching skill is related to drawing self-efficacy. Sketching has the largest impact in the early stages of design. The final research goal of this project is to investigate the relationship between sketching and creativity in the early stages of design. Through experiments of idea generation and sketching abilities, we hope to better understand to what degree sketching enables creativity in design. To summarize, this project seeks to improve sketching skill through Sketchtivity. We are accomplishing this through expanding reach at multiple universities and expanding the capabilities of the software. It is also essential to understand the implications of improving sketching skill. This is being investigated through improved evaluation of sketching and investigations of sketching’s relationship to drawing self-efficacy and creativity

Impact of a sketch-based tutoring system at multiple universities

Large class sizes in engineering programs often prevent instructors from providing detailed and meaningful feedback to students on their homework problems. While the literature shows that frequent and immediate formative feedback has several benefits in terms of knowledge gain and academic motivation, several instructors struggle to provide any feedback. Motivated by this inability, a sketch-based virtual tutoring system, named Mechanix, has been developed and implemented. Mechanix lets the students to sketch their freebody diagram on a virtual interface and the process involved is very close to using a pencil and paper. The system provides real-time feedback on the accuracy of their Freebody diagrams and the solution to the problem. This paper reports the implementation of Mechanix at two large public universities in the United States - Georgia Institute of Technology and Texas State University. Mechanix is used to solve specific assignments from each school that involve the use of freebody diagrams. Pre- and post- concept inventories are used to measure the improvements in the conceptual understanding of the students. The results show that students who solve their homework using Mechanix outperform their peers who do not in one school, whereas the results are similar across the two groups in the second school. The evaluation of the concept inventories shows that the students who used Mechanix has the same level of improvement in their conceptual knowledge compared to the control group