❒ Revealing causes of phenomenon observed
Investigation of molten metal drops falling down through the air
Situation
When a metal is welded, its drops fall down through the air. However, the falling of the drops is slower than that of metal balls of the same size. What brings about the phenomenon?
Cause-and-effect model of the situation
Selected causes
| Flattening out molten metal drop due to aerodynamic force |
| Creation of uprising convective flow in heated air layer around molten metal drop |
❒ Revealing consequences of phenomenon observed
Electromagnet
Situation
An electromagnet is used to create an alternating magnetic field. The electromagnet consists of a cylinder-like coil, a wire, and a ferromagnetic core. The core in inserted into the coil to increase the intensity of the magnetic field. As the electromagnet works, a number of undesirable side effects arise. It is necessary to reveal those effects which hamper the electromagnet functioning.
Cause-and-effect model of the situation
Selected consequences
| Failure of electromagnet wire under high-intensity current |
| Abrupt decrease in magnetic intensity due to heating of electromagnet core above Curie point |
❒ Revealing substitute goals
Disinfection of water
Under natural conditions, water is contaminated with bacteria and algae. It can be disinfected with silver and copper atoms. Silver atoms affect bacteria, and copper atoms do algae. For this purpose, plates made of silver-copper alloy are put in contaminated water.
In an installation the number of plates is selected to disinfect averagely contaminated water. If contamination is strong, disinfection takes much time. If contamination is slight, the concentration of silver and copper atoms in the water after disinfection can exceed the maximum allowable level.
Another disadvantage of the installation is high consumption of silver and copper which are so valuable. This fact should be taken into account when disinfecting water in pools.
Goal model of situation
Selected goals
| Control rate of dissolution of silver and copper atoms in contaminated water |
| Control rate of diffusion of silver and copper atoms into water |
| Control coefficient of diffusion of silver and copper atoms into water |