Mechanics of gelation distinction between a sol (solution) and a gel therefore appears to be understood in a manner analogous to the practical distinction between the elastic and plastic deformation ranges of a metal. The distinction lies in the ability to respond to an applied shear force via macroscopic viscous flow. In a dynamic sense, the response of a gel to an alternating force (oscillation or vibration) will depend upon the period or frequency of vibration. As indicated here, even most simple liquids will exhibit some elastic response at shear rates or frequencies exceeding 5 x 10 cycles per second. Experiments on such
Material input per service unit (MI) of the product can be reduced or amount of service units (S) can be increased. Material input in the production phase can be reduced by using less energy or raw materials. Also transport chains can be rationalized. In the use phase the material input per unit of service can be reduced when amount of service produced is increased. For instance in case of a newspaper the material input can be reduced by using recycled paper instead of primary. Material input per reader decreases when the same paper is shared with several persons. High quality products and availability of spares