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1_) Present Worth Method Uniform ( New ) ( Better ) ( Cost Analysis Methods )

There are two generally accepted methods of conducting life-cycle cost analysis: the present worth and the uniform annual cost methods. Present worth involves using the discount rate to express the cost of future expenditures in terms of present dollars. When various alternatives are considered, an expenditure stream for each alternative must be estimated and the total present costs of those alternatives compared. Other factors being equal, the alternative with the lowest present worth would be the most desirable.

Decision makers who are facing different investment situations when selecting alternatives use several well developed engineering economy techniques to analyze those alternatives. The common economic analysis techniques that take the time value of money into account and are used in selecting the alternatives are the present worth method the future worth method and the annual worth method.

The present worth method is an economic method that involves the conversion of all of the present and the future expenses to a base of today's costs. The present worth of some planned future expenditure is equivalent to the amount of money that would need to be invested now at a given compound interest rate for the original investment plus interest to equal the expected cost at the time it is needed.

( Kenneth H. McGhee,National Research Council (U.S.). Transportation Research Board, Portland Cement Concrete Resurfacing, pg. 36 )

( Cengiz Kahraman, Fuzzy Engineering Economics with Applications, pg. 71 ) 

( T. Ceran,Robert Brian Newman,National Research Council (U.S.). Transportation Research Board,American Association of State Highway and Transportation Officials, Maintenance Considerations in Highway Design, 349 th, pg. 80 )
Present worth method uniform: ( Old )

For the life cycle cost analysis,present worth is the sum of all costs(and benefits) over the project life in today's dollars.It combines initial costs with discounted future maintanence costs,rehabilitation costs and a salvage value.The future costs are discounted to account for the time value of money using the discount(real interest) rate.Present worth analysis is limited to comparing alternatives with equal analysis period.

(Tushar K. Ghosh,Mark A. Prelas,Energy resources and systems:Fundamentals and non renewable,p:55)

2_) Mechanic pulverization ( New ) ( Better ) ( Powder Metallurgy Methods )

For relatively brittle materials such as intermetallic compounds, and ferro-alloys, mechanical pulverization is sufficient to produce metallic powders. This process uses a ball or rod mill, a cylindrical-shaped steel container filled with ceramic balls or rods, respectively. As the grinding mill is rotated, the grinding media collides with the ore/metallic compound effectively grinding the material into a fine powder. Either alumina or zinconia represents the most common ceramic material used within grinding mills. This procedure is also commonplace for refining iron powder from the co-grinding and post-annealing of the ore with carbon. Refractory metals are normally refined through the reduction of oxides with hydrogen gas.

( Bradley D. Fahlman, Materials Chemistry, pg. 172 )

Mechanic Pulverization (17:17) ( Old )
The method involves breaking down of metals into small particles through crushing and milling in ball mills. The method is used for brittle metals only such as antimony and is not suitable for ductile metals like steels and other non-ferrous metals, as they do not get properly powdered and tend to take the form of flakes due to crushing action in ball mills.

(Manufacturing Processes Second Edition, Yazar: J. P. Kaushish, Page 736)