Rigorous Case Control Structure

For the simulation with external heat exchangers for the reboiler and condenser, the temperature and pressure loops have the same controlled variables but different manipulated variables than those used in the base case. 

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Risk evaluation programmes exist, for pressure vessels, which take into account European Directives [12] the risk factor - related to material brittleness and embrittlement, corrosion effects and localised stresses - is elevated and requires the adoption of rigorous safety measures. The manufacture and control procedures - including welding parameters and structural solutions - should be, in this case, more accurate and devoted to avoid the described defects. 

Repairs to a structure such as an aircraft are particularly critical. Procedures have to be rigorously evaluated and specifications carefully followed. Repairs need to take account of aerodynamic considerations, mechanical clearance, lightning protection and drainage requirements, and in the case of control surfaces, weight and balance is also important. 

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