Discipline
Differential Equations Digital Signal Processing Control Theory
Textiles
Automobile Engineering (Motors - 3 Phase AC | Parts: Commutator, Armature, Brush, Bearing, Housing, Coil, Magnet, Stator, Rotor | Concepts: Magnetic Induction, Reluctance, Hysterisis, Field Strength, Flux | Related: Inductance, Capacitance, Impedance)
Metallurgy
Music: Sound waves that have a repeating waveform are called music. It can be composed of several waveforms, but basically it is consistent. These are fundamental to musical notations. This is also why only some people have good voices for singing.