In so-called “Ufology“ Close Encounters of the Second Kind is an UFO event in which a physical effect is alleged. This will not be about UFOs, but I borrowed this phrase because I think it kind of describes how I feel about writing my Bachelor’s thesis this academic year. Since now I only have been absorbing and processing some of the information science gained, through all those years. And that was the Close Encounter of the First Kind with Science. Now there is a completely different situation ahead of me. And that is to observe and describe something to details based on this information, which is the Close Encounter of the Second Kind with science.
Now that I have explained the strange title, I’d like to describe the already mentioned Bachelor’s thesis. For now, the description will be very brief and simple in order to enlighten this topic also to a reader without any information from control theory, for instance, a high school student.
The whole thing is about the reactor, which is in the picture below. Basically, it blends two chemicals together. In my case, it is water solution of citric acid and sodium hydroxide. The chemical reaction between them is called neutralization, while products of this reaction are salt and water. Different amounts of each cause a different pH value in the reactor and a different amount of salt to be created
My goal is to control the process using two pumps that fill the reactor. And by the word control, I mean being able to get the desired pH value. This will be done by the intentional change of flow in one of two pumps, while the extent of the change will be calculated by computer using programming language MATLAB. This means designing a controller to control the process. But before I will try to control this mechanism I need to know its behavior. So since the last semester, I am gathering information about this system. The best way to do that is to do some experiments. Doing these experiments I am looking for an answer to this question: How does the pH value change when an amount of base or acid suddenly changes? This question and answer are a very simplified definition of a step response.
I need several step responses in order to find a mathematical relation between input, which is the flow of base or acid and output, which is the pH value. This mathematical relation is called transfer function and it is essential for controller design which is also a goal of my work.
And in case you wonder what it looks like in those blue containers it looks like water.
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