Statistical functions - two scales

These statistical correlation functions were used as the reference systems in the annealing micro-structural reconstruction. Each sample was reconstructed and simulated five times with a different random series. In this reconstruction, relative porosities (O/) were determined by the statistical analysis of SEM micrographs and verified by the total experimental porosity obtained by mercury intrusion porosimetry. CL thickness (e) was also determined by SEM. CLs were studied by SEM at different resolutions. 

Nevertheless, for the simulation study, two micrometric scales were empirically selected  

It is important to point out that the nano-metric scale ( inside an agglomerate scale) was not experimentally studied. Nevertheless, the CL internal micro-structure was characterized at 5000 x resolution. In this scale we can define stochastic micro-pores but it is not possible to define CL primary components (Pt, C and ionomer). On the other hand, because the DECAL technique (used for the fabrication of CLs) generates very thin CLs (10-20 p.m), the 500 x resolution characterizes a macro-superficial and isotropic structure. 

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