Customer Solutions

Using LabVIEW in Distance Education Lab Exercises

Author(s):

Michael Axelson, University of Göteborg

Industry:

University/Education

Product:

LabVIEW

The Challenge:

Developing real lab exercises for distance education courses in Zoophysiology that introduce the concept of different exchange principles, teach students how to calculate efficiency of different exchange systems, and enable discussions about physiological implications of different exchangers

The Solution:

Enabling distance education students to complete lab exercises using LabVIEW interfaces to access the control of the pumps and functions involved in the Web-based experiment.

Distance Education Lab Exercises
In the past, we have been unsuccessful in sending computer simulations to students because students did not to like pure computer-based simulations.

After looking through the distance education examples on ni.com, I though that it would be interesting to see if the students accepted this type of computer-operated real lab exercises.

Introduction to the Subject of Exchange Mechanisms
An exchange processes, whether it involves heat, gases, solutes, or water, is an important feature in many different physiological processes. On of the most effective exchange principles is the counter-current principle. We can use the exchanger for transferring heat, gases, or water between two media separated by a thin membrane that has good thermal conductance or a high conductance for different gases, solutes or water. Depending on the flow arrangements, we can classify an exchanger as counter-exchanger, con-exchanger or cross-counter exchanger. A fourth type is the mixing-heat-exchangers, where we mix the two in the exchanger, such as the nasal passages in some animals and some human applications. The efficiency of the exchanger is dependent on a number of factors, such as the flow direction of the media, the flow rate of the media and diffusion distance, or conductance of the exchanger material.

Online Experiment Setup
The image to your right is a schematic drawing of the setup with numbers that refer to the items in this section. Students use thermostated baths (1) to set the different temperatures – in this case one bath is set to 5 °C and the other to 37 °C. Students use two peristaltic pumps (2) to pump water from the two baths through the heat-exchanger model (3). Students measure the temperature in the exchanger at 4 locations along each of the two tubes in the heat exchanger model. Using the interface module (4), students measure the temperature and enter the information in a computer (6). The computer controls the two pumps through a control box (5) and sends an alarm signal to an external alarm box (7) every time a person logs on through the Web as a notification for the responsible teacher or PhD student.
Students can view the lab by installing the web-cam.

The exchanger model consists of two soldered 1-meter-long copper tubes. We inserted four thermocouples in each tube to monitor the temperature along each tube using an 8-channel thermocouple interface connected to the PC.

The computer records the temperature along the exchanger and controls the two peristaltic pumps. Students can save data and download it over the net. The interface that the students see in their Web browser includes the LabVIEW VI interface, a link to the Web camera, and a link to a chat that the students use during the lab exercise if they are not at the same location.

The LabVIEW VI is simple, and students can access the control for the two pumps and start and stop saving data. They also can see who is currently logged on. The temperature data is shown in two different ways – the default is the “Time Diagram” with temperature for each pair of thermocouples shown against time, and the alternative is “Temperature Diagram” with the temperature shown in a schematic representation of the exchanger.

Evaluation and future
The lab exercise have so far been tested and evaluated during a traditional campus-based course, where half the student were present in the lab with the equipment and the other half were running the lab from our computer lab using the remote panel function. While students expressed mixed feelings about the “reality feeling” compared to the other practical lab exercises, they agreed that in a distance education course, it would be a useful addition to the curriculum.

For more information, contact:
Michael Axelson
University of Göteborg, Department of Zoology
Box 463, SE-405 30 Göteborg, Sweden
+46-31-773 3689
+46-31-773 3807
E-Mail M.Axelsson@zool.gu.se