improving the soil quality with organic matter content and presence of elements such as n, p and k are some of sewage sludge benefits. adjusting carbonaceous materials such as plant wastes to dewatered sludge compost increases its moisture and improves c/n ratio. so dewatered sludge has low c/n ratio and should be mixed with bulking agents. this study was performed in a three months period of t...

‎In this paper‎, ‎some algebraic and geometrical properties of the rank$-k$ numerical hulls of normal matrices are investigated‎. ‎A characterization of normal matrices whose rank$-1$ numerical hulls are equal to their numerical range is given‎. ‎Moreover‎, ‎using the extreme points of the numerical range‎, ‎the higher rank numerical hulls of matrices of the form $A_1 oplus i A_2$‎, ‎where $A_1...