Engineering design motivations : a qualitative and quantitative analysis of university students

What motivates students to perform and pursue engineering design tasks? This study examines this question by way of three Learning Through Service (LTS) programs: 1) an on-going longitudinal study examining the impacts of service on engineering students, 2) an on-going analysis of an international senior design capstone program, and 3) an on-going evaluation of an international graduate-level research program. The evaluation of these programs incorporates both qualitative and quantitative methods, utilizing surveys, questionnaires, and interviews, which help to provide insight on what motivates students to do engineering design work. The quantitative methods were utilized in analyzing various instruments including: a Readiness assessment inventory, Intercultural Development Inventory, Sustainable Engineering through Service Learning survey, the Impacts of Service on Engineering Students’ survey, Motivational narratives, as well as some analysis for interview text. The results of these instruments help to provide some much needed insight on how prepared students are to participate in engineering programs. Additional qualitative methods include: Word clouds, Motivational narratives, as well as interview analysis. This thesis focused on how these instruments help to determine what motivates engineering students to pursue engineering design tasks. These instruments aim to collect some more in-depth information than the quantitative instruments will allow. Preliminary results suggest that of the 120 interviews analyzed Interest/Enjoyment, Application of knowledge and skills, as well as gaining knowledge are key motivating factors regardless of gender or academic level. Together these findings begin to shed light on what motivates students to perform engineering design tasks, which can be applied for better recruitment and retention in university programs.

Impact of E22 on two-stroke and four-stroke snowmobiles

A push to reduce dependency on foreign energy and increase the use of renewable energy has many gas stations pumping ethanol blended fuels. Recreational engines typically have less complex fuel management systems than that of the automotive sector. This prevents the engine from being able to adapt to different ethanol concentrations. Using ethanol blended fuels in recreational engines raises several consumer concerns. Engine performance and emissions are both affected by ethanol blended fuels. This research focused on assessing the impact of E22 on two-stroke and four-stroke snowmobiles. Three snowmobiles were used for this study. A 2009 Arctic Cat Z1 Turbo with a closed-loop fuel injection system, a 2009 Yamaha Apex with an open-loop fuel injection system and a 2010 Polaris Rush with an open-loop fuel injection system were used to determine the impact of E22 on snowmobile engines. A five mode emissions test was conducted on each of the snowmobiles with E0 and E22 to determine the impact of the E22 fuel. All of the snowmobiles were left in stock form to assess the effect of E22 on snowmobiles currently on the trail. Brake specific emissions of the snowmobiles running on E22 were compared to that of the E0 fuel. Engine parameters such as exhaust gas temperature, fuel flow, and relative air to fuel ratio (λ) were also compared on all three snowmobiles. Combustion data using an AVL combustion analysis system was taken on the Polaris Rush. This was done to compare in-cylinder pressures, combustion duration, and location of 50% mass fraction burn. E22 decreased total hydrocarbons and carbon monoxide for all of the snowmobiles and increased carbon dioxide. Peak power increased for the closed-loop fuel injected Arctic Cat. A smaller increase of peak power was observed for the Polaris due to a partial ability of the fuel management system to adapt to ethanol. A decrease in peak power was observed for the open-loop fuel injected Yamaha.

Understanding Michigan nonindustrial private forest landowners attitudes and knowledge about forest management

Approximately one-fourth of the non-industrial private forestland (NIPF) owners in the state of Michigan, who collectively own approximately 50% of the private forested land, have conducted commercial timber harvest in recent years. Previous studies indicated that NIPFs preferred to manage their forest for a sustained yield of high-quality timber, but were limited to even-aged regeneration treatments or conversion for uneven-aged silviculture due to previous cuttings. Improved knowledge about NIPF’s intentions and forest management behavior could be useful for successful implementation of sustained yield management. This study’s objective was to identify more active NIPF’s attitudes towards timber management, their forest management practices and whether their forest management behavior leads or leads not to q management for sustained yield. Active NIPF’s intentions to harvest timber for biofuels and its suitability with NIPF’s forest management behavior will be discussed. Phone interviews of 30 NIPFs who have experience with commercial timber harvests were conducted between August and October 2011. All interviews were recorded, transcribed, and analyzed for identifying NIPF’s motivations, attitudes, forest management behavior and forestry related knowledge. Interviewees, whether consciously or not, tended to manage their land for a sustained yield and they would be willing to harvest timber for biofuels facility as long as it benefits landowners management goals.

Control design and genetic algorithm optimization for electrostatic MEMS

This dissertation discusses structural-electrostatic modeling techniques, genetic algorithm based optimization and control design for electrostatic micro devices. First, an alternative modeling technique, the interpolated force model, for electrostatic micro devices is discussed. The method provides improved computational efficiency relative to a benchmark model, as well as improved accuracy for irregular electrode configurations relative to a common approximate model, the parallel plate approximation model. For the configuration most similar to two parallel plates, expected to be the best case scenario for the approximate model, both the parallel plate approximation model and the interpolated force model maintained less than 2.2% error in static deflection compared to the benchmark model. For the configuration expected to be the worst case scenario for the parallel plate approximation model, the interpolated force model maintained less than 2.9% error in static deflection while the parallel plate approximation model is incapable of handling the configuration. Second, genetic algorithm based optimization is shown to improve the design of an electrostatic micro sensor. The design space is enlarged from published design spaces to include the configuration of both sensing and actuation electrodes, material distribution, actuation voltage and other geometric dimensions. For a small population, the design was improved by approximately a factor of 6 over 15 generations to a fitness value of 3.2 fF. For a larger population seeded with the best configurations of the previous optimization, the design was improved by another 7% in 5 generations to a fitness value of 3.0 fF. Third, a learning control algorithm is presented that reduces the closing time of a radiofrequency microelectromechanical systems switch by minimizing bounce while maintaining robustness to fabrication variability. Electrostatic actuation of the plate causes pull-in with high impact velocities, which are difficult to control due to parameter variations from part to part. A single degree-of-freedom model was utilized to design a learning control algorithm that shapes the actuation voltage based on the open/closed state of the switch. Experiments on 3 test switches show that after 5-10 iterations, the learning algorithm lands the switch with an impact velocity not exceeding 0.2 m/s, eliminating bounce.

THERMAL CHARACTERIZATION OF A GASOLINE TURBOCHARGED DIRECT INJECTION (GTDI) ENGINE UTILIZING LEAN OPERATION AND EXHAUST GAS RECIRCULATION (EGR)

The push for improved fuel economy and reduced emissions has led to great achievements in engine performance and control. These achievements have increased the efficiency and power density of gasoline engines dramatically in the last two decades. With the added power density, thermal management of the engine has become increasingly important. Therefore it is critical to have accurate temperature and heat transfer models as well as data to validate them. With the recent adoption of the 2025 Corporate Average Fuel Economy(CAFE) standard, there has been a push to improve the thermal efficiency of internal combustion engines even further. Lean and dilute combustion regimes along with waste heat recovery systems are being explored as options for improving efficiency. In order to understand how these technologies will impact engine performance and each other, this research sought to analyze the engine from both a 1st law energy balance perspective, as well as from a 2nd law exergy analysis. This research also provided insights into the effects of various parameters on in-cylinder temperatures and heat transfer as well as provides data for validation of other models. It was found that the engine load was the dominant factor for the energy distribution, with higher loads resulting in lower coolant heat transfer and higher brake work and exhaust energy. From an exergy perspective, the exhaust system provided the best waste heat recovery potential due to its significantly higher temperatures compared to the cooling circuit. EGR and lean combustion both resulted in lower combustion chamber and exhaust temperatures; however, in most cases the increased flow rates resulted in a net increase in the energy in the exhaust. The exhaust exergy, on the other hand, was either increased or decreased depending on the location in the exhaust system and the other operating conditions. The effects of dilution from lean operation and EGR were compared using a dilution ratio, and the results showed that lean operation resulted in a larger increase in efficiency than the same amount of dilution with EGR. Finally, a method for identifying fuel spray impingement from piston surface temperature measurements was found. Note: The material contained in this section is planned for submission as part of a journal article and/or conference paper in the future.