Prime requisites

Since the invention of rotary rigs, used for drilling oil and gas wells, scientists have been searching for fluids that will both facilitate the drilling process and provide maximum productivity once the well is completed. There are two prime requisites for all well fluids. These are ... 

Economic Factors. Economic factors are related to the availability and cost of the propellant as well as the cost of the equipment required to transport, store, and supply the propellant. Generally, low cost is a prime requisite for a propellant which will be utilized in large quantities and/or in multiunits (i.e., booster stages of launch vehicles and in military weapons). However, where utilization of a high-cost propellant may be required to complete the mission, the cost factor can be of secondary importance. This situation is usually associated with upper stages of a space launch vehicle. 

Where viewing systems are necessary, the choice of materials creates unusual problems because radiation stability of the transparent properties of the materials is a prime requisite. There is a tendency toward color... 

Transformation from the crystalline to amorphous state can be initiated by either homogeneous point defect accumulation or heterogeneous displacement cascade collisions (Trinkaus 1997). The prime requisite for this is the high mobility of radiation defects. However, in the case of oxide ceramics, the mobility of the radiation defect is very low so that thermally activated recrystallization occurs at high rate compared to the defect production (Motta 1990, Weber et al. 1994). Hence, all of the specimens remained crystalline for the investigated irradiation conditions as confirmed from the XRD studies except for the Li implanted MgO films. 

A prime requisite in all static methods, as has already been emphasized in the discussion of measurements in the low-pressure range, is that all air must be eliminated from the sample. With the apparatus just described, this is confirmed by checking the constancy of the vapour pressure measured over the full range from the dew volume to the bubble volume in the course of the volumetric measurements. 

The coating industry has met these problems with blends of alkyds and heat-reactive amino resins. With such vehicles, adequate performance can be achieved through baking cycles of 30—40 min at temperatures of 250—300°F. In general, where initial color and color retention are the prime requisites, nondrying alkyds are most widely used. 

The rechargeable silver oxide batteries are noted for their high specific energy and power density. The high cost of the silver electrode, however, has limited their use to applications where high specific energy or power density is a prime requisite, such as lightweight medical and electronic equipment, submarines, torpedoes, and space applications. The characteristics of the silver oxide secondary batteries are summarized in Table 33.1. 

In studying any one type of exchanger, heat transfer and pressure drop data are not the only characteristics of interest. Mechanical strength is a prime requisite. Serious attention is always given to the method of fabrication. Cyclic pressurization tests as well as pressure destruction tests are usually performed. It is beyond the scope of this paper to present the heat transfer, pressure drop, and other test data for each type of exchanger described. 

Abrasive ceramics are used to wear, grind, or cut away other material, which necessarily is softer. Therefore, the prime requisite for this group of materials is hardness or wear resistance in addition, a high degree of toughness is essential to ensure that the abrasive particles do not easily fracture. Furthermore, high temperatures may be produced from abrasive frictional forces, so some refractoriness is also desirable. 

A level uncertainty of only 1 mm (0.04 in) or 0.01 percent in a 10 m (33 ft) tall, 50.000 m tank (315,000 bbl), equals 5 m (31 bbl). Hence accuracy is a prime requisite for good inventory management however, it is only one of the many aspects involved in tank gauging. Rebabibty to prevent product spills and safety of the environment and personnel are equally important. 

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