Oxidative stabilization is a key process for polyacrylonitrile (PAN)-based carbon materials. During this process, oxygen has a significant influence on the formation of cyclization structure and crosslinking structure of PAN matrix. Here, graphene oxide (GO) was used as filler in PAN matrix, the structure evolution of GO/PAN composite was studied during oxidative stabilization. Solubility measurement revealed that the crosslinking degree increased, while the cyclization degree of stabilized films decreased after GO incorporation. The effect of GO on the structure of PAN film was characterized by XRD, DSC, DMA, FTIR, and XPS. These results verified that GO could initiate the cyclization reaction of PAN at a lower temperature. The carboxylic groups on GO sheets might take part in the cyclization reactions during the heat treatment. Moreover, the oxygen-containing molecules released from GO decomposition during the heat treatment were beneficial to the formation of crosslinking structure. The possible mechanism of the structure evaluation was proposed in this article.

I-V curve and MPP are key parameters for solar cell performance measuring. A low-cost testing system based on Zig bee for outdoor solar cell outdoor measuring is presented in this paper. The testing algorithm combining constant scale and incremental conductance algorithm is discussed. Interpolation method for I-V curve reconstruction and its error source are analyzed. This paper also reports the specific structure of our outdoor solar cell testing system. Using the developed algorithm and test system, we present a detailed numerical investigation and experiments about distributed outdoor solar cell measurement. The results show that this method can provide high-precision solar cell characters measuring with low complexity.Keywords-photovoltaic power system; 1-V curve measurement; maximum power point; wireless sensor networks; ZigBee I.