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Primitive instancing:The modeling system defines a set of primitive 3D solid shapes that are relevant to the application area.Primitive instancing is often used for relatively complex objects, that are tedious to define in terms of boolean combination of simpler objects, yet are readily characterized by a few high level parameters.In primitive instancing no provisions are made for combining objects to form a new higher level object.Thus the only way to create a new kind of object is to write the code that defines it.Similarly the routines that draw the objects or determine their mass properties must be written individually for each primitive.(James D. Foley, computer graphics: principles and practice,p:539)
International tolerance grade(IT):A group of tolerances that vary depending on the basic size but that provide the same relative level of accuracy within a given grade.(Edward G. Hoffman Christopher J: Mccauley,Shop reference for students and apprentices,p:223)
Present worth method uniform: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)
Annual cost method:Equivalent uniform annual cost spreads the cost of all items (initial startup costs,user fees,maintanence,and anticipated rehabilitation costs) annually over the life cycle of project.An analysis using equivalent uniform annual cost more effectively compares alternates with different service lives.However when making such comparisons the user must understand that during analysis it is assumed that the same set of activities will be repeated indefinitely.(Tushar K. Ghosh,Mark A. Prelas;Energy resources and systems:Fundementals and non renewable,p:55)