Thursday, January 30, 2014

The first paper on learning analytics for assessing engineering design?

Figure 1
The International Journal of Engineering Education published our paper ("A Time Series Analysis Method for Assessing Engineering Design Processes Using a CAD Tool") on learning analytics and educational data mining for assessing student performance in complex engineering design projects. I believe this is the first time learning analytics was applied to the study of engineering design -- an extremely complicated process that is very difficult to assess using traditional methodologies because of its open-ended and practical nature.

Figure 2
This paper proposes a novel computational approach based on time series analysis to assess engineering design processes using our Energy3D CAD tool. To collect research data without disrupting a design learning process, design actions and artifacts are continuously logged as time series by the CAD tool behind the scenes, while students are working on an engineering design project such as a solar urban design challenge. These "atomically" fine-grained data can be used to reconstruct, visualize, and analyze the entire design process of a student with extremely high resolution. Results of a pilot study in a high school engineering class suggest that these data can be used to measure the level of student engagement, reveal the gender differences in design behaviors, and distinguish the iterative (Figure 1) and non-iterative (Figure 2) cycles in a design process.

From the perspective of engineering education, this paper contributes to the emerging fields of educational data mining and learning analytics that aim to expand evidence approaches for learning in a digital world. We are working on a series of papers to advance this research direction and expect to help with the "landscaping" of  those fields.

Saturday, January 18, 2014

Fireplaces at odd with energy efficiency? An Energy2D simulation

In the winter, a fireplace is the coziest place in the house when we need some thermal comfort. It is probably something hard to remove from our living standards and our culture (it is supposed to be the only way Santa comes into your house). But is the concept of fireplace -- an ancient way of warming up a house -- really a good idea today when the entire house is heated by a modern distributed heating system? In terms of energy efficiency, the advice from science is that it probably isn't.

Figure 1. A fire is lit in the fireplace.
When the wood burns, a fireplace creates an updraft force that draws the warm air from the house to the outside through the chimney. This creates a "negative pressure" that draws the cold air from the outside into the house through small cracks in the building envelope. This is called the stack effect. So while you are getting radiation heat from the fireplace, you are also losing heat in the house at a faster rate through convection. As a result, your furnace has to work harder to keep other parts of your house warm.

Figure 2. No fire.
Our Energy2D tool can be used to investigate this because it can simulate both the stack effect and thermostats. Let's just create a house heated by a heating board on the floor as shown in the figures in this article. The heating board is controlled by a thermostat whose temperature sensor is positioned in the middle of the house. A few cracks were purposely created in the wall on the right side to let the cold air from the outside in. Their sizes were exaggerated in this simulation.

Figure 1 shows the duty cycles of the heating board within two hours when the house was heated from 0 °C to 20 °C with a fire lit in the fireplace. A heating run is a segment of the temperature curve in which the temperature increases, indicating the house is being heated. In our simulation, the duration of a heating run is approximately the same under different conditions. The difference is in the durations of the cooling runs. A more drafty house tends to have shorter cooling runs as it loses energy more quickly. Let's just count those heating runs. Figure 1 shows that 15 heating runs were recorded in this case.

Figure 2 shows the case when there was no fire in the fireplace and the fireplace door was closed. 13 heating runs were recorded in this case.

What does this result mean? This means that, in order to keep the house at 20 °C, you actually need to spend a bit more on your energy bill when the fireplace is burning. This is kind of counter-intuitive, but it may be true, especially when you have a large drafty house.

Figure 3. In a house without cracks...
How do we know that the increased energy loss is due to the cracks? Easy. We can just nudge the window and the wall on the right to close the gaps. Now we have a tight house. Re-run the simulation shows that  only 11 heating runs were recorded (Figure 3). In this case, you can see in Figure 3 that the cooling runs lasted longer, indicating that the rate of heat loss decreased.

Note that this Energy2D simulation is only an approximation. It does not consider the radiation heat gain from the fireplace. And it assumes that the fire would burn irrespective of air supply. But still, it illustrates the point.

This example demonstrates how useful Energy2D may be for all precollege students. In creating this simulation, all I did is to drag and drop, change some parameters, run the simulation, and then count the heating runs. As simple as that, this tool could be a game changer in science and engineering education in high schools or even middle schools. It really creates an abundance of learning opportunities for students to experiment with concepts and designs that would otherwise be inaccessible. Similar experiences are currently only possible at college level with expensive professional software that typically cost hundreds or even thousands of dollars for just a single license. Yet, according to some of our users, our Energy2D rivals those expensive tools to some extent (I would never claim that myself, though).

Thursday, January 9, 2014

The time of infrared imaging in classrooms has arrived

At the Consumer Electronics Show (CES) 2014, FLIR Systems debuted the FLIR ONE, the first thermal imager for smartphones that sells for $349. Compared with standalone IR cameras that often cost between $1,000 and $60,000, this is a huge leap forward for the IR technology to be adopted by millions.

With this price tag, FLIR ONE finally brings the power of infrared imaging to science classrooms. Our unparalleled Infrared Tube is dedicated to IR imaging experiments for science and engineering education. This website publishes the experiments I have designed to showcase cool IR visualizations of natural phenomena. Each experiment comes with an illustration of the setup (so you can do it yourself) and a short IR video recorded from the experiment. Teachers and students may watch these YouTube videos to get an idea about how the unseen world of thermodynamics and heat transfer looks like through an IR camera -- before deciding to buy such a camera.

For example, this post shows one of my IR videos that probably can give you some idea why the northern people are spraying salt on the road like crazy in this bone-chilling weather. The video demonstrates a phenomenon called freezing point depression, a process in which adding a solute to a solvent decreases the freezing point of the solvent. Spraying salt to the road melts the ice and prevents water from freezing. Check out this video for an infrared view of this mechanism! 

Wednesday, January 8, 2014

Dart projects of Energy2D and Quantum Workbench announced

Update: I have decided to suspend these Dart projects due to the uncertainty of the future of the language following Google's decision to not bundle the Dart VM into Chrome. At this point, I have to fall back to JavaScript.

Last month, Google announced Dart 1.0, a new programming language for the Web that aims to greatly accelerate Web development. Dart uses HTML5 as the UI. It can either run on the Dart Virtual Machine being built in Chrome or be compiled into JavaScript to run in other browsers. Dart can also be used to create standalone apps (I guess it is meant to be the main programming language for Google's own Chrome OS) or server-side software. An ECMA Technical Committee (TC 52) has been formed to make Dart into an international standard.

This is the moment I have been waiting for. As a developer with C/Java background, I am not convinced that JavaScript is made for large, complex projects (as Web programming seems to be moving towards) -- even after reading many articles and books about JavaScript. The facts that after ten years Google Docs still has only a tiny fraction of functionality of Word and basic functions such as positioning an image have not improved much suggest that its JavaScript front end has probably reached its limit.

Don't get me wrong. JavaScript is an excellent choice for creating interactive Web experiences. I use JavaScript extensively to create Web interfaces for interacting with the Energy2D applet. But I think it is in general healthy for the developer community if we are given more options. Recognizing the weaknesses of JavaScript, the community has already created CoffeeScript and TypeScript (supersets of JavaScript that strips off unproductive features of JavaScript) that also require compilation into native JavaScript. Dart is Google's solution to these problems that should be welcomed. To a Java developer like me, Dart provides a much better option because it returns the power of class-based object-oriented programming to developers who must create Web-based front ends. What is even sweeter is that its SDK provides a familiar Eclipse-based programming platform that makes many developers feel at home.

Excited about the potential of this new language (plus it is from Google and will be highly performant on Chrome), I am announcing the development of the Dart versions of our Energy2D and Quantum Workbench software. These software are based on complex mathematical solutions of extremely complex partial differential equations and will hopefully provide some showcases to anyone interested in Dart. This is not to say the development of the Java versions will cease. We are committed to develop and maintain both Dart and Java versions.

Hopefully 2014 will be an exciting year for us!