ABSTRACT
Fluid systems can be divided into pneumatics and hydraulics. A pneumatic system is one in which the fluid is compressible, whereas a hydraulic system is one in which the fluid is incompressible. A general type of incompressible liquid systems is the liquid-level system. These systems are operated by adjusting the heights or levels of liquids in storage tanks. A thermal system is one in which thermal energy is stored or transferred. The mathematical model of a thermal system is often complicated because of the complex temperature distribution throughout the system. Partial, rather than ordinary, differential equations are required for precisely analyzing such a distributed-parameter system. Pneumatic systems are often used in industry, particularly for pneumatic switches, pneumatic actuators, compressed-air engines, air brakes on buses and trucks, and so on. The working medium in a pneumatic system is compressible gas, typically air.
