In order to determine the reasonable shape of the patching plate for the corrosion defects in the bottom of crude oil storage tank, this paper used finite element analysis to calculate the changes of the stress value in the corrosion defects after repairing different patching plate shapes, and then investigated the stress distribution and the safety factor value of the patching plate, and finally gave the best shape of the patching plate for the bottom of 20 000 m³ crude oil storage tank in Liaohe oil field. The results show that the best shape of the patching plate is a round patching plate. After repairing the corrosion defect, the stress value in the corrosion defect only decreases with the increase of the radius of the patching plate after the repair of the corrosion defect, and does not change with the change of the depth and radius of the defect. With the increase of the radius of the patch plate, the cost and safety of the patch plate will also increase, the specific size of the patch plate should be developed in accordance with the actual situation of the project. The results of the study can give theoretical guidance to the tank bottom repair from a scientific point of view.

To solve the overlap of part of fault classes in the analog circuit fault diagnostics, a novel analog circuit fault diagnostics approach based on quantum neural networks algorithm was presented. Kurtosis and entropy were calculated as features after the time domain response signals of the circuit under test were measured, and then the different fault classes were identified by quantum neural networks algorithm. The simulation demonstrated that constructed neural network had simple network structure and the fault diagnosis accuracy was higher, which reached 99.62%.

Aiming at the actual situation of the buried sulfur natural gas pipeline leakage problem, with the finite volume method, the numerical simulation for volume fraction of hydrogen sulfide and methane of the buried sulfur natural gas pipeline continuous leakage were preceded. The upper soil was considered as porous medium to gas diffusion effects. Comparing and analyzing the dangerous area of methane and hydrogen sulfide occurring at the moment, the results show that the virulent area of hydrogen sulfide leaked is much greater than the dangerous area of methane, covering completely. Between the common area of hydrogen sulfide and methane, fire prevention measures are took as well as poisonous protection measures in the area of hydrogen sulfide influenced alone.

New carbon-based solid acid catalyst was synthesized from starch and p-toluene sulfonic acid，and applied for the preparation of biodiesel with soybean oil and ethanol. The effect of reaction conditions such as the reaction time, reaction temperature, the molar ratio of ethanol with soybean oil, the amount of catalyst to the yield of biodiesel was investigated. The new carbon-based solid acid catalyst shows high catalytic activity and good stability, and can easily be separated from the products. The optimal conditions are: the molar ratio of ethanol to soybean oil 8∶1, the amount of catalyst is the quality of soybean oil 7.0%（w）, reaction time 8 h , reaction temperature 80 ℃. Under optimum condition, the yield of biodiesel could reach 67.4%.