Predicting flow reversals in chaotic natural convection using data assimilation

A simplified model of natural convection, similar to the Lorenz (1963) system, is compared to computational fluid dynamics simulations in order to test data assimilation methods and better understand the dynamics of convection. The thermosyphon is represented by a long time flow simulation, which serves as a reference "truth". Forecasts are then made using the Lorenz-like model and synchronized to noisy and limited observations of the truth using data assimilation. The resulting analysis is observed to infer dynamics absent from the model when using short assimilation windows. Furthermore, chaotic flow reversal occurrence and residency times in each rotational state are forecast using analysis data. Flow reversals have been successfully forecast in the related Lorenz system, as part of a perfect model experiment, but never in the presence of significant model error or unobserved variables. Finally, we provide new details concerning the fluid dynamical processes present in the thermosyphon during these flow reversals

Threshold Concepts Theory in Higher Education—Introductory Statistics Courses as an Example

The purpose of this research was to identify “threshold” concepts in introductory statistics courses by surveying engineering students. Threshold concepts are those ideas that bind a subject together and are fundamental to the thinking and practice within a discipline. In this exploratory study, the aim was to answer the following questions: What are the learners’ assessments of the proposed threshold concepts? Based on the learners’ assessments, which of the four threshold characteristics best describes the selected threshold concepts? What are the final proposed threshold concepts that incorporate the learners’ perspectives? What is the perception held by learners about the theory’s impact on the learning and teaching processes? Using qualitative and quantitative exploratory analysis to answer these questions, all students in the College of Engineering and Applied Science who took one of the 29 sections of the course Introductory Statistics offered at the University of Colorado at Boulder were surveyed. The findings reveal there are differences in threshold concepts identified by instructors and learners. The learners added 11 concepts to the 18 proposed by the instructors as threshold concepts. Based on these inputs, a list of potential threshold concepts incorporating the two perspectives—that of instructor and that of learner—was created, and a framework of knowledge to support curriculum design was developed. An important suggestion for future research is to explore how to incorporate these threshold concepts in redesigning the syllabi of such courses, depending on the proposed framework

Threshold Concepts Theory in Higher Education—Introductory Statistics Courses as an Example

The purpose of this research was to identify “threshold” concepts in introductory statistics courses by surveying engineering students. Threshold concepts are those ideas that bind a subject together and are fundamental to the thinking and practice within a discipline. In this exploratory study, the aim was to answer the following questions: What are the learners’ assessments of the proposed threshold concepts? Based on the learners’ assessments, which of the four threshold characteristics best describes the selected threshold concepts? What are the final proposed threshold concepts that incorporate the learners’ perspectives? What is the perception held by learners about the theory’s impact on the learning and teaching processes? Using qualitative and quantitative exploratory analysis to answer these questions, all students in the College of Engineering and Applied Science who took one of the 29 sections of the course Introductory Statistics offered at the University of Colorado at Boulder were surveyed. The findings reveal there are differences in threshold concepts identified by instructors and learners. The learners added 11 concepts to the 18 proposed by the instructors as threshold concepts. Based on these inputs, a list of potential threshold concepts incorporating the two perspectives—that of instructor and that of learner—was created, and a framework of knowledge to support curriculum design was developed. An important suggestion for future research is to explore how to incorporate these threshold concepts in redesigning the syllabi of such courses, depending on the proposed framework