Collaborative Experimentation and Simulation: A Pathway to Improving Student Conceptualization of the Essentials of System Dynamics and Control Theory

The overarching goal of this research is to improve conceptualization of System Dynamics and Controls concepts by incorporating a Web-facilitated curriculum to enable intercampus collaboration and remotely-accessible or virtual systems. This approach will complement lecture-based curricula and will strongly enhance students’ conceptualization and exposure to System Dynamics and Controls fundamentals by providing less restricted exposure to a variety of systems that encompass the more important Dynamic Systems concepts. The plan involves the development of a System Dynamics Concepts Inventory and the implementation and assessment of three Web-enabled laboratory formats: (1) inter-campus collaborative experimentation, (2) remotely-accessible experiments, and (3) virtual system experiments. Each format has its inherent advantages and disadvantages. Remotely-accessible experiments, for example, can be made more readily available to students outside of regular laboratory hours, but the lack of hands-on exposure limits the potential scope of the experiments. Each format has been preliminarily implemented using a variety of dynamics systems that reflect some of the more important fundamentals pertinent to System Dynamics. These activities are currently being incorporated into a laboratory course at the University of Texas at San Antonio (UTSA) and a lecture course at the University of Texas - Pan American (UTPA). A preliminary Course Inventory is being developed in collaboration with faculty at both institutions. An initial assessment of each laboratory format has been completed. This paper reports on the findings including a detailed discussion of the development of the Course Inventory, a discussion of the pros and cons of implementing each format, and an evaluation of the impact of each format in addressing student conceptualization of a few key fundamentals

Utilizing an Emporium Course Design to Improve Calculus Readiness of Engineering Students

The intervention has targeted incoming students in Engineering and Computer Sciencedegrees. Participating students were selected who had a record of participation in Pre-Calculus classes in high school, but who had not demonstrated their readiness to take Calcu-lus, as measured by placement tests and existing credit. The course design uses an emporiummethod, specifically the Assessment and Learning in Knowledge Spaces (ALEKS) software,in a computer lab to deliver to students an intensive program of mathematical practice andexploration. The course design is meant to take advantage of students? existing knowledge,rewarding them for it in fact, and focus them on specific Algebra and Trigonometry topicsin which they need more practice and one-on-one instruction [1, 2]. The purpose of this activity is to accelerate the Calculus preparedness for a subset ofstudents held back due to standardized test scores and perhaps limited mastery of the prereq-uisite content. The benefits are improved engineering readiness, reduced time-to-graduation,and improved performance in gatekeeper courses. To maintain student interest, and connect the problems and topics they are working indetail on, we included in the course cooperative activities with engineering problems asso-ciated with railway safety and transportation; making use of tours of existing laboratoriesand experimental apparatuses. This combination of a problem focused course, tailored toindividual student?s needs and experiences, emphasizing mastery, and then motivated bydirect connections to current engineering problems and research is providing for an impor-tant improvement in the engineering degree experience for a subset of students who wouldtraditionally be at a disadvantage in their program.References[1] Twigg, C. A. (2011, May-June). The Math Emporium: Higher Education’s Silver Bullet. Change: The Magazine of Higher Learning.[2] Fine, A., Duggan, M., & Braddy, L. (2009). Removing remediation requirements: Effec- tiveness of intervention programs. PRIMUS, 19(5), 433?446

Small-Scale and Large-Scale Interventions to Improve [State] Student’s College Readiness

We are conducting two interventions aimed at improving entering students’ college readiness and mathematics placement. The small-scale intervention is aimed at working with students on the university campus. Students who are targeted have high school course work indicating that they have experience in Calculus or Pre-Calculus courses, but whose placement tests have not indicated they are ready for Calculus. At our institution this is a significant number of students and the goal of the project is to develop methods to address and accelerate students in this category. The course design, to take advantage of the students’ prior experience, emphasizes practice and mastery using a commercial software [1]. The large-scale intervention is a high school course developed by [Author1] for local high schools. Students who have completed their high school mathematics course work but who have not achieved the state’s college readiness standard [2] are targeted. The students in the course have had experience in their high school classes in all of the concepts in the state standard, but have not had the chance to practice and master the material. The course we have developed emphasizes practice and mastery like the small-scale one, but participating school districts could not afford the commercial software. Thus we have built a course around the WebWork software [3] that is available through a free and open license. [1] Assessment and Learning in Knowledge Spaces, https://www.aleks.com/ , McGraw Hill. [2] [State] College and Career Readiness Standard and Assessment [3] WebWork Homework Software, http://webwork.maa.org/ , Mathematical Association of America

Guided Discovery Modules for Statics and Dynamics

Students struggle to conceptualize Engineering Mechanics (i.e. Newtonian Physics, Statics, and Dynamics) fundamentals because they cannot successfully visualize the effects of external loads on physical systems and/or do not intuitively comprehend the static or dynamic response. Traditionally, Engineering Mechanics courses like Statics and Dynamics have been primarily lecture-based with little experimentation. The authors contend that through the use of inquirybased, multimodal activities, lower-division engineering students can more effectively interpret Engineering Mechanics concepts. Instructors must place emphasis on engendering properly conceived engineering intuition and contextualizing concepts and fundamentals. The authors hypothesize that by utilizing often simple, multimodal, inquiry-based exercises, instructors can better overcome misconceptions. A novel methodology termed “guided discovery” is presented herein. It borrows aspects of challenge-based and discovery learning. The method, however, is optimized for short in-class activities and homework assignments. Several modules are presented to illustrate the processes used and some preliminary results are included

I M E C E2002-DSC-34288 VARIABLE FIDELITY MODELING OF VEHICLE RIDE DYNAMICS USING AN ELEMENT ACTIVITY METRIC

ABSTRACT The evolving ability of vehicle simulation packages continues to facilitate the use of complex models for virtual prototyping. In formulating a virtual proving ground for conducting vehicle mission studies, it can be helpful to devise ways to facilitate the synthesis of models optimized for repetitive study of specific missions or maneuvers. Because subsystem models may have inherently different bandwidth characteristics, complex vehicle simulations that incorporate such models may be numerically stiff. Furthermore, complexity generally makes it difficult to interpret results and identify key parameters that affect dominant dynamics. The intent of this study is to examine the feasibility of optimizing simulation efficiency and/or enhancing physical insight using a variable fidelity approach that switches between reduced sub models optimized for specific dynamic intervals of the mission study. Because of its established use for model reduction, element activity is tested as a metric to measure and vary model fidelity of a vehicle ride mode model

Toward a Fast-Response Active Turbine Tip Clearance Control

This paper describes active tip clearance control research being conducted by NASA to improve turbine engine systems. The target application for this effort is commercial aircraft engines. However, technologies developed for clearance control can benefit a broad spectrum of current and future turbomachinery. The first portion of the paper addresses the research from a programmatic viewpoint. Recent studies that provide motivation for the work, identification of key technologies, and NASA's plan for addressing deficiencies in the technologies are discussed. The later portion of the paper drills down into one of the key technologies by presenting equations and results for a preliminary dynamic model of the tip clearance phenomena

Improved Temperature Dynamic Model of Turbine Subcomponents for Facilitation of Generalized Tip Clearance Control

This paper describes efforts conducted to improve dynamic temperature estimations of a turbine tip clearance system to facilitate design of a generalized tip clearance controller. This work builds upon research previously conducted and presented in and focuses primarily on improving dynamic temperature estimations of the primary components affecting tip clearance (i.e. the rotor, blades, and casing/shroud). The temperature profiles estimated by the previous model iteration, specifically for the rotor and blades, were found to be inaccurate and, more importantly, insufficient to facilitate controller design. Some assumptions made to facilitate the previous results were not valid, and thus improvements are presented here to better match the physical reality. As will be shown, the improved temperature sub- models, match a commercially validated model and are sufficiently simplified to aid in controller design

A Vibration Energy Approach Used to Identify Temperature Trending in Railroad Tapered-Roller Bearings

Bearing temperature trending is a phenomenon that has plagued the railroad industry for decades and has resulted in costly train stoppages and non-verified bearing removals. Initial experimental studies conducted at The University of Texas-Pan American to explore this troubling phenomenon identified potential sources for the abrupt changes in temperature exhibited by some railroad bearings. The authors hypothesize that vibration-induced rollermisalignment is the root cause for bearing temperature trending. Hence, subsequent research focused on providing validation for the proposed hypothesis through vibration monitoring techniques. To that end, dynamic testers were used to run railroad bearings at the various speeds and loads that they experience in the field. A “trigger” bearing with a known cup raceway defect was used as a vibration source to induce roller misalignment on neighbouring defect-free bearings. Results show that the vibration energy of a bearing would decrease prior to an increase in temperature. In theory, misaligned rollers would vibrate less, leading to a decrease in the overall vibration energy, while also generating sufficient friction to account for the observed temperature increase. Typically, rollers realign themselves through geometrical thermal expansions or changes in the operating conditions, thus, returning to normal temperature and vibration levels. This paper outlines the research findings

Thermal Modeling of a Railroad Tapered-Roller Bearing Using Finite Element Analysis

In the railroad industry, distressed bearings in service are primarily identified using wayside hot-box detectors (HBDs). Current technology has expanded the role of these detectors to monitor bearings that appear to “warm trend” relative to the average temperatures of the remainder of bearings on the train. Several bearings set-out for trending and classified as nonverified, meaning no discernible damage, revealed that a common feature was discoloration of rollers within a cone (inner race) assembly. Subsequent laboratory experiments were performed to determine a minimum temperature and environment necessary to reproduce these discolorations and concluded that the discoloration is most likely due to roller temperatures greater than 232 °C (450 °F) for periods of at least 4 h. The latter finding sparked several discussions and speculations in the railroad industry as to whether it is possible to have rollers reaching such elevated temperatures without heating the bearing cup (outer race) to a temperature significant enough to trigger the HBDs. With this motivation, and based on previous experimental and analytical work, a thermal finite element analysis (FEA) of a railroad bearing pressed onto an axle was conducted using ALGOR 20.3™. The finite element (FE) model was used to simulate different heating scenarios with the purpose of obtaining the temperatures of internal components of the bearing assembly, as well as the heat generation rates and the bearing cup surface temperature. The results showed that, even though some rollers can reach unsafe operating temperatures, the bearing cup surface temperature does not exhibit levels that would trigger HBD alarms