Hydraulic parameters of culverts from pipes with normal and spiral form of corrugation

The research paper is devoted to study of culverts from metal corrugated pipes (CMP) and helically corrugated steel pipes (HCSP). Modern design solutions of culverts from CMP and HCSP are differ as compared with used before (bottom with various types of roughness, inlet and outlet heads, type and size of corrugation) and there is not enough experimental data for their design. The aim of the study is to test CMP and HCSP models to determine their hydraulic parameters, such as roughness and resistance coefficient, critical bias and so on. The laboratory equipment and method of experimental study as well as results of the tests of CMP and HCSP with protective tray at the pipe bottom and without it under different operation modes are given in the research paper. The results of the study show that roughness coefficient under pressure hade mode can be determined using Norton equation only for HCSP, Norton and Einstein-Banks equations are corrected for CMP. © Published under licence by IOP Publishing Ltd

On the stability of Li intercalated fine grained graphitic material

In order to study the performance, cycling stability and safety of electrochemical storage devices, various characterisation methods are applied. Magic angle spinning MAS NMR enables ex situ studies of electrochemical reactions with high resolution. In the present work, we follow the changes that occur in the MAS NMR spectra of lithiated graphitic materials after storage. The measuring time has been significantly shortened by using fine grained graphitic material with 65 13C isotope enrichment. Our results show that for 13C graphitic electrode material with a low lithiation degree, visible changes in the 13C NMR spectra are observed already in few hours, whereas the samples with a higher lithiation degree demonstrated greater stability even after several days. We analyzed the deintercalation behavior in these materials using 7Li MAS NMR and oxidation processes using in situ X ray photoelectron spectroscopy. During storage Li ions migrate to the other interlayers redistribution , large pores and to the surface, where interaction with air takes place. Effects of charge transfer from Li to graphite across four graphitic layers guarantees that 13C NMR spectra are less affected by these effects. The key finding is that special care has to be paid to the ex situ characterisation of electrochemically prepared graphitized material