In view of the characteristics of coalbed methane "multi-point intervening, flexible gathering" and the complex flow pattern of the gas-water two-phase flow in the pipe, under the complicated terrain, the pipeline network pressure fluctuates frequently, seriously affecting the gas gathering and transportation system efficiency and operational safety. In order to more accurately calculate the pressure of the pipe network, based on the multiphase hydraulic and thermodynamic calculation method, the steady-state calculation model of coal-bed gas pipeline network is established by using the pipe network node method. A method of steady-state simulation of segmented pipe network considering terrain fluctuation is put forward. Through the calculation and analysis of the pipe network, it can be seen that the pressure calculation results of the pipe network calculation model under the terrain fluctuation are more accurate and reliable, which provide a reference for rational design and operation of coalbed gas pipeline network in complex terrain.

Nanometer bismuth oxide powders were prepared by hydrothermal synthesis method which used bismuth nitrate
solutions as crude material ,strong aqua ammonia as mineralizerd and chose pH in the range of 7~10. The photocatalytic
performances of the samples were estimated by degrading Rhodamine B .The results show that the reaction of photocatalytic
degradation of Rhodamine B follows the surface first law .When pH is 8.5 ,the photocatalytic performance is the optimal .Results of X － ray diffraction (XRD),Transmission electron microscopy (TEM ) and Infra － red (FT － IR) show that the
samples contain bismuth oxide,ammonium nitrate crystal .With pH increasing ,content of bismuth oxide increase and their
structures are excellent .The bismuth oxide powders are spherical shape or strip and connect to networks .When pH is8.5 ,the nanometer networks are even thickness and net wires are homogeneous .