The Modified Direct Analysis Method: an Extension of the Direct Analysis Method

The purpose of this research project is to study an innovative method for the stability assessment of structural steel systems, namely the Modified Direct Analysis Method (MDM). This method is intended to simplify an existing design method, the Direct Analysis Method (DM), by assuming a sophisticated second-order elastic structural analysis will be employed that can account for member and system instability, and thereby allow the design process to be reduced to confirming the capacity of member cross-sections. This last check can be easily completed by substituting an effective length of KL = 0 into existing member design equations. This simplification will be particularly useful for structural systems in which it is not clear how to define the member slenderness L/r when the laterally unbraced length L is not apparent, such as arches and the compression chord of an unbraced truss. To study the feasibility and accuracy of this new method, a set of 12 benchmark steel structural systems previously designed and analyzed by former Bucknell graduate student Jose Martinez-Garcia and a single column were modeled and analyzed using the nonlinear structural analysis software MASTAN2. A series of Matlab-based programs were prepared by the author to provide the code checking requirements for investigating the MDM. By comparing MDM and DM results against the more advanced distributed plasticity analysis results, it is concluded that the stability of structural systems can be adequately assessed in most cases using MDM, and that MDM often appears to be a more accurate but less conservative method in assessing stability.

Development of the Heat and Energy Concept Inventory: Preliminary Results on the Prevalence and Persistence of Engineering Students' Misconceptions

BACKGROUND Students frequently hold a number of misconceptions related to temperature, heat and energy. There is not currently a concept inventory with sufficiently high internal reliability to assess these concept areas for research purposes. Consequently, there is little data on the prevalence of these misconceptions amongst undergraduate engineering students. PURPOSE (HYPOTHESIS) This work presents the Heat and Energy Concept Inventory (HECI) to assess prevalent misconceptions related to: (1) Temperature vs. Energy, (2) Temperature vs. Perceptions of Hot and Cold, (3) Factors that affect the Rate vs. Amount of Heat Transfer and (4) Thermal Radiation. The HECI is also used to document the prevalence of misconceptions amongst undergraduate engineering students. DESIGN/METHOD Item analysis, guided by classical test theory, was used to refine individual questions on the HECI. The HECI was used in a one group, pre-test-post-test design to assess the prevalence and persistence of targeted misconceptions amongst a population of undergraduate engineering students at diverse institutions. RESULTS Internal consistency reliability was assessed using Kuder-Richardson Formula 20; values were 0.85 for the entire instrument and ranged from 0.59 to 0.76 for the four subcategories of the HECI. Student performance on the HECI went from 49.2% to 54.5% after instruction. Gains on each of the individual subscales of the HECI, while generally statistically significant, were similarly modest. CONCLUSIONS The HECI provides sufficiently high estimates of internal consistency reliability to be used as a research tool to assess students' understanding of the targeted concepts. Use of the instrument demonstrates that student misconceptions are both prevalent and resistant to change through standard instruction.

Fidelity of Implementation of Research-Based Instructional Strategies (RBIS) in Engineering Science Courses

Background Increasing attention is being paid to improvement in undergraduate science, technology, engineering, and mathematics (STEM) education through increased adoption of research-based instructional strategies (RBIS), but high-quality measures of faculty instructional practice do not exist to monitor progress. Purpose/Hypothesis The measure of how well an implemented intervention follows the original is called fidelity of implementation. This theory was used to address the research questions: What is the fidelity of implementation of selected RBIS in engineering science courses? That is, how closely does engineering science classroom practice reflect the intentions of the original developers? Do the critical components that characterize an RBIS discriminate between engineering science faculty members who claimed use of the RBIS and those who did not? Design/Method A survey of 387 U.S. faculty teaching engineering science courses (e.g., statics, circuits, thermodynamics) included questions about class time spent on 16 critical components and use of 11 corresponding RBIS. Fidelity was quantified as the percentage of RBIS users who also spent time on corresponding critical components. Discrimination between users and nonusers was tested using chi square. Results Overall fidelity of the 11 RBIS ranged from 11% to 80% of users spending time on all required components. Fidelity was highest for RBIS with one required component: case-based teaching, just-in-time teaching, and inquiry learning. Thirteen of 16 critical components discriminated between users and nonusers for all RBIS to which they were mapped. Conclusions Results were consistent with initial mapping of critical components to RBIS. Fidelity of implementation is a potentially useful framework for future work in STEM undergraduate education.

A Method for Assessing the Sustainability of Design in Developing World Projects

Projects for the developing world usually find themselves at the bottom of an engineer’s priority list. There is often very little engineering effort placed on creating new products for the poorest people in the world. This trend is beginning to change now as people begin to recognize the potential for these projects. Engineers are beginning to try and solve some of the direst issues in the developing world and many are having positive impacts. However, the conditions needed to support these projects can only be maintained in the short term. There is now a need for greater sustainability. Sustainability has a wide variety of definitions in both business and engineering. These concepts are analyzed and synthesized to develop a broad meaning of sustainability in the developing world. This primarily stems from the “triple bottom line” concept of economic, social, and environmental sustainability. Using this model and several international standards, this thesis develops a metric for guiding and evaluating the sustainability of engineering projects. The metric contains qualitative questions that investigate the sustainability of a project. It is used to assess several existing projects in order to determine flaws. Specifically, three projects seeking to deliver eyeglasses are analyzed for weaknesses to help define a new design approach for achieving better results. Using the metric as a guiding tool, teams designed two pieces of optometry equipment: one to cut lenses for eyeglasses and the other to diagnose refractive error, or prescription. These designs are created and prototyped in the developed and developing worlds in order to determine general feasibility. Although there is a recognized need for eventual design iterations, the whole project is evaluated using the developed metric and compared to the existing projects. Overall, the success demonstrates the improvements made to the long-term sustainability of the project resulting from the use of the sustainability metric.