In Changqing oilfield,the pipelines between Jingsi and Jingsan consociation station is vital for the waxy crude oil pipelining.The wax deposition,however,triggers huge economic,safe and efficient problems to the pipeline operation.A series of polyacrylate paraffin inhibitor (WI) with various side chain carbon number distributions were first synthesized by free radical polymerization,and the structural properties and crystallization properties were characterized by using the FTIR and DSC method.Then,the effects of the WIs on the rheological properties of the Changqing waxy crude oil were studied.The results show that after adding 400 mg/kg WI⁃2,the pour point of Changqing crude oil can be reduced by 10 ℃,the anomalous point can be decreased by 8 ℃,and the viscosity of non⁃Newtonian fluid region can be greatly reduced.After that,based on the indoor wax deposition experiment,the influences of the WI on the Changqing crude oil wax deposit properties were studied by settling various conditions and the wax deposition models of Changqing crude oil undoped /doped with WIs were developed.Using the wax deposition models to predict the wax deposit under the field operation condition,it is found that without adding WIs,the prediction error of the wax deposit thickness at different time is less than 5%,and the wax inhibition efficiency can reach 88%~95% after adding 400 mg/kg WI⁃2.

A slide mode control－common model control（SMC－CMC） controller was proposed to deal with the time－variable and complexity of the switching mode power converters．Using the state－space average modeling method，a nonlinear model of BUCK converter working on current conduction mode （CCM） was set up．Dynamic neural network which was constructed based
on a number of integrators and RBF neural network was employed to approximate the inverse model of the dynamic system． Using this inverse model to build a CMC controller．The introduction of slide mode control was to improve the robustness of controller．The modeling and simulation of system was implemented under Matlab／Simulink．The result of simulation confirms
show that the SMC－CMC control schemes are capable of reduced steady state error and improve controll‐er's reliability during supply change and load variations．