Environmental Engineering Reference
In-Depth Information
Figure 10 is a sample course material common to Physics or Engineering majors. One main
topic of such majors is load analysis with Free Body Diagrams (FBD). Figure 10 gives a
typical example of the force analysis. On left is a block resting on a slanted surface. As
shown on right, students need to set up a proper coordinate system, draw the forces, and
then write down the governing equations on each direction to find out the magnitudes of
the forces.
Before the class, the teacher prepares questions like the one shown in the left part of Figure
10 and makes copies on regular paper. In the class time, the teacher first explains the
concepts of FBD and provides examples. Then the handouts with the questions will
distributed to the class. The students put the handouts on the writing surfaces of the Z-
Writers and then write their answers on the paper just like any other classes. The Z-Writers
transfer the results to the host computer for the teacher to review in real time. The teacher is
then able to adjust the next step accordingly, such as revisiting the subject, moving on to the
next topic, or giving annotations to selected answers. At the end of the class, the students
will carry their own paper home while the teacher keeps a soft copy of all answers for future
reference.
g
θ
Fig. 10. A typical example of load and motion analysis. Left: Given by teacher. Right:
Student answer.
6. Conclusion
In this article, we introduced a novel method of using stereovision (PLUS) and monovision
(PLUM) to locate the position of a pointer on a display unit.
6.1 Benefits of the optical touch screen with virtual force
There are many advantages of the algorithms proposed in this article.
1.
Low cost
. It is relatively easy and inexpensive to implement. Thanks to the ubiquitous
camera phones and webcams, low-cost high-resolution single-chip digital cameras are
widely available today.
2.
Durable
. There is no physical contact between the camera and the pointer. Therefore,
the functionality of the screen will not deteriorate due to wear and tear. Even when the
screen is scratched or broken, the touch function will still work.
3.
Easy to scale up
. The complexity and cost of existing touch screens increase quickly
when the screens become larger. For example, when the size of a screen doubles, its
