Voltage-drop calculations and power-flow studies for rural electricdistribution lines

The history of distribution system voltage-drop and loss calculation from paper-and-pencil methods to full three-phase power flow calculations using the digital computer is examined. The methods discussed include an approach that allows unbalanced operation (such as an open-wye line) to be analyzed accurately. It is suggested that intelligent use of the models will entail using the more detailed models only if necessary, thereby avoiding unnecessary computational expense. It is much more important to use a reasonable value for the load power factor than to account exactly for every small unbalance in the line impedances. Recommendations to aid the practicing engineer in the choice of the best analytical tools are offered     

Effect of ultrasonication and other processing conditions on the morphology,thermomechanical, and piezoelectric properties of poly(vinylidene difluoride‐trifluoroethylene) copolymer films

This study is carried out on the effect of processing conditions including preparation methods, ultrasonication, film thickness, and thermal annealing on the thermal, mechanical, and piezoelectric properties of copolymer of poly(vinylidene difluoride‐trifluoroethylene) (P(VDF‐TrFE)). Free‐standing films and films on substrates are prepared by solvent casting and spin‐coating, respectively. The results obtained by differential scanning calorimetry show that the Curie transition of the copolymer films was influenced by the preparation methods, with very little difference in the melting transition. The difference was attributed to a less uniform distribution of TrFE comonomer units within the crystalline and amorphous regions of the spin‐coating films. However, no effect of the preparation methods on the piezoelectric properties of the films was observed. It is also found that the short ultrasonication, film thickness higher than critical value of crystallization of P(VDF‐TrFE) (about 100 nm), and drying before annealing did not have a significant effect on the properties of the films. Surprisingly, the ultrasonication had a clear impact on the relaxations at high temperature of the polymer chains. In addition, this study indicates that a short annealing by 10 min at 140°C was enough to obtain well‐crystallized films, which is interesting from the industrial point of view. POLYM. ENG. SCI., 54:1280–1288, 2014. © 2013 Society of Plastics Engineers     

Refining the Dynamic Network of T2SS Endopilus Tip Heterocomplex Combining cw-EPR and Nitroxide–GdIII Distance Measurements

The type 2 secretion system (T2SS) is a bacterial nanomachine composed of an inner membrane assembly platform, an outer membrane pore and a dynamic endopilus. T2SS endopili are organized into a homo-multimeric body formed by the major pilin capped by a heterocomplex of four minor pilins. The first model of the T2SS endopilus was recently released, even if structural dynamics insights are still required to decipher the role of each protein in the full tetrameric complex. Here, we applied continuous-wave and pulse EPR spectroscopy using nitroxide-gadolinium orthogonal labelling strategies to investigate the hetero-oligomeric assembly of the minor pilins. Overall, our data are in line with the endopilus model even if they evidenced conformational flexibility and alternative orientations at local scale of specific regions of minor pilins. The integration of different labelling strategies and EPR experiments demonstrates the pertinence of this approach to investigate protein–protein interactions in such multiprotein heterocomplexes.