Search results for "Concentration distribution"
showing 2 items of 2 documents
Current distribution along electrodialysis stacks and its influence on the current-voltage curve: behaviour from near-zero current to limiting plateau
2023
The current maldistribution along the flow path of electrodialysis (ED) units is a well-known phenomenon. However, it has been poorly quantified via experimental tests so far. This work aimed at measuring the current distribution in an ED stack with 40 cm path length, provided with four-segment electrodes. The current-voltage curve (CVC) of each segment was recorded under several operating conditions of inlet concentrations and feed velocity. In the CVC of the first segment, the current increased approaching a saturation, while in that of the remaining segments it passed through a maximum and then settled at near-zero values when high voltage values were applied. The current fraction on the…
Compared regimes of NDVI and Rainfall in semi-arid regions of Africa
2006
International audience; Bi-monthly normalized difference vegetation index (NDVI) at an 8km spatial resolution from the advanced very high resolution radiometers (AVHRR) was used from 1981 to 1995 to analyse the vegetation response to rainfall supply in semi-arid regions of Africa. Within the 200-600 mm annual rainfall belt, for which the apparent NDVI response to rainfall was the strongest, three regions were selected which exhibited different patterns in their NDVI regimes and/or relationships with rainfall. The regions, located in western, southern and eastern Africa, were split into coherent sub-regions in terms of mean regime of photosynthetic activity through a cluster analysis. Overal…