The main target of this paper is to determine the optimum time for preventive maintenance on machines. Tow methods has been implemented estimating the optimum time duration for preventive maintenance . the first techniques use scheduling depending on data concerning the machine maintenance cost and halted cost from the production reach to the optimum time for maintenance which reflect the minimum cost. Where as the second techniques depends on reability function to estimate the optimum duration time which reflect the minimum cost. The tow techniques above by which we count on in fixing the preventive maintenance both give same result . we also prove that the scheduling method best than the reability function .

في هذا البحث حضر الكاربون المنشط ذو الحجم الحبيبي في المدى المايكروي والمدى النانوي من قشور الجوز واجريت عملية الكربنة باستخدام فرن المايكرويف ومن ثم استعمل محلول (%50) من حامض الفسفوريك مع المادة المكربنة وبأزمان مختلفة (2,4,8,16,24) ساعة لتحديد الزمن الأفضل لعملية التنشيط في هذا البحث ، وبعد ذلك اضيفت نسب وزنية مختلفة من مخلفات بولي بروبلين عند زمن (8) ساعة وكانت النسب 0.05):,1 0.1:,1 0.15:0.2 ,1: (1:0.25 ,1 للمضاف البوليمري ومس

This research work involves the preparation of nano activated carbonand macro activated carbon from corn seeds with a various mixing ratio ofpotassium hydroxide (1:0, 1:0.2, 1:0.4, 1:0.6, 1:0.8 and 1:1) % using thermaland micro radiation carbonization to identify the best mixing ratio. At studyto confirmed that the efficiency and effectiveness of the prepared of activatedcarbon samples increase when ratio potassium hydroxide increase with athermal and micro radiation carbonization was used. The study of samplesexternal surface area was performed via studying the adsorption of methyleneblue from their aqueous solution, also measured the internal surface area wasperformed via studying the adsorption of iodine from their aqueous solution.Measu