Hinge system

An impressive achievement of this strategy has been the construction of three-dimensional structures. Utilizing branched phenylacetylene sequences, double cyclization yielded macrobicyclic arrays 54 and 55 [43]. The zenith of Moore s approach is macrotricycle 56, a freely hinged system with a sizable 36xl2xl2A molecular cavity [44]. 

A typical electrode for tear-seal work would be hinged on a top plate, the hinges insulated (for example, by polypropylene blocks) a lay-up then is placed on the bottom plate, the unit closed and fitted under the head for welding. Hinged systems such as this have many applications—as in making pre-cut covers for books, where card or board inserts must be placed as close to the electrode as possible, to ensure a close fit after welding. 

January 1967 206 Door Latches and Door Hinge Systems Federal Std. No. 515/5a (GSA)... 

Fig. 13. Semirigid piping systems (a) two-hinge arrangement (b) universal-type arrangement.

A number of alternative pricing systems have been proposed that hinge on turbine efficiency and the relative pricing of fuel and electricity. AH... 

Heat Pumps. A heat pump is a refrigeration system that raises heat to a useful level. The most common appHcation is the vapor recompression system for evaporation (qv) (Fig. 14). Its appHcation hinges primarily on low cost power relative to the alternative heating media. If electricity price per unit energy is less than 1.5 times the cost of the heating medium, it merits a close look. This tends to occur when electricity is generated from a cheaper fuel (coal) or when hydroelectric power is available. 

FIG. 10-170 Hinged expansion joint. (From Kellogg, Design of Piping Systems, Wiley, New York, 1965.)... 

The reliability of molecular mechanics calculations hinges entirely on the validity and range of applicability of the force field. The parameterisation of these functions (the force field) represents the chemistry of the species involved. Many force fields have been developed and the one used in any application usually depends on the molecular mechanics package being used. The force field itself can be validated against experimental and ab initio results. Because of the relative speed of molecular mechanics calculations, it is possible to consider routine calculations of a large number of atoms, certainly tens of thousands, which makes the method amenable to calculations on polymers. To remove surface effects, calculations of bulk properties are normally carried out employing 3D periodic boundaries. In this way it is possible to perform calculations on both amorphous and crystalline systems. 

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