30 October 2010

It's Halloween in Western countries and just another normal day in Eastern countries. However, in Auckland, right now in the University of Auckland, it's our exams! I just had my first paper today, this morning. It was not too bad la. Most questions can do but not all questions can do, which means A+ should be quite far away from my reach eh.. :(

Well, after the test, went to lunch with housemates at a Korean place. Another let down... Sucky food! The place which I wanted to eat at was not open so just have to go to another one. Anyways, after I reach home, I was feeling really tired all of a sudden. Dunno why. I had enough sleep but am just so tired! So, took a nap.

Woke up, hungry. Ordered pizzas. Whole house had pizzas. 18 inch pizzas! Huge as.... Haha. Then studied. Tonight, I learned new stuffs. WARNING: skip these two paragraphs if u dun wanna bore urslf out! I know that when u = curl a, it follows that the divergence of the field is 0. The divergence of a field gives the volume change per volume of the field. Both these results means that in that field, an equivoluminal wave is produced. When the equivoluminal result is substituted into Navier's equation, we get the 3D wave equation which with some manipulation, gives the speed of the wave.

These results are useful for earthquake detection. In earthquakes, two types of waves are produced - p-waves and s-waves. P-waves are irrotational waves (also called waves of dilatation) while s-waves are equivoluminal waves (also called shear waves or waves of distortion). Both waves deflect and diffract at surfaces and boundaries while traveling at different speeds with p-waves traveling at a faster speed. These characteristics makes earthquakes and its epicentre predictable. It can be done by detecting p-waves and the epicentre can be pin-pointed by drawing arcs around each recording stations which detect the waves.

Very technical eh? Haha. I guess I need to write it down to remember. So, ignore it if u think it's too boring or technical la. :P