Bins and hoppers are used in a wide range of industries, such as agriculture, mining, chemical engineering, power plants, cement and food processing, where most bulk solids storage, handling and transportation systems are applied. One of the most important requirements is that the material should discharge smoothly and continuously when the outlet is opened. One practical problem involved in designing the handling systems for particulate materials is the attainment of an adequate flow of material and the control of the flow at some desired r