A single terminal fault location method for overhead transmission lines in general interconnected power system with n⁃bus was proposed. High accuracy in fault location was achieved by using both an accurate distributed parameters model for the faulted transmission line, and a two⁃bus Thevenin equivalent network model for the power system that accurately accounted for its inter connectivity. The method was tested by using transient fault data obtained from MATLAB simulations of an 11⁃bus interconnected power system. The results show that the method is capable of estimating the fault distance with high accuracy for various fault conditions. And it is sensitive to errors in the value of the local bus impedance, but insensitive to errors in the value of the remote bus impedance.

The corrosion damage mechanism of heat exchanger in visbreaking unit was studied, through field morphology observation, scanning electron microscopy (SEM) micromorphology, energy spectrum analysis (EDS) and corrosion coupon experiments, and find out the naphthenic acid corrosion damage reason of the exchange tube heat exchanger and baffle plate, further analyzes the naphthenic acid corrosion mechanism of carbon steel; Then through a variety of material corrosion coupon experimental comparison, the anti⁃corrosion measures are put forward. The research results show that the corrosion of heat exchanger leakage and crude oil viscosity device, high acid value, the water content of the working temperature of heat exchanger and the material, dehydration of crude oil and reasonable change of the working temperature and material of the heat exchanger can effectively reduce the corrosion damage of the heat exchanger of the viscosity reducing device.

The geometrical structure of the 1,2,3⁃triazole compounds was optimized by B3LYP/6⁃31G* in density functional theory (DFT), and the obtained structure was confirmed to be the optimal structure by frequency calculation. Based on the optimized configuration, the frontier orbital energy levels and energy gaps of compounds were analyzed. The charge of ADCH in the molecule was calculated, and the theoretical absorption spectra, fluorescence emission wavelengths and IR spectra of these compounds were simulated. Through the analysis of the hydrogen bond interaction with HIV⁃1 protease, it is concluded that this series of derivatives is expected to be used as an imaging anti⁃protein inhibitor. In addition, the reaction mechanism between β⁃lactam carbene and 3,6⁃dipyrazine⁃1,2,4,5⁃tetrazine was studied, and the synthesis mechanism was further clarified, which provided a theoretical basis for the future synthesis of the series of compounds. This provides a theoretical basis for the synthesis of this series of compounds in the future.

The effect of alkali metal modification on g-C ₃N ₄ photocatalyst was systematically studied. The density functional theory is used to explain the microscopic mechanism of different alkali metal modification on improving photocatalytic activity from the various angles of geometry and electronic structure. The results show that the binding energies of alkali metals and g-C ₃N ₄ become weaker and weaker with the increase of the number of extra-nuclear electronic layers of Li, Na, K and Rb atoms, and the influence on the structure of g-C ₃N ₄ is weaker and weaker. The electronic structure analysis shows that Li, Na, and K atoms have an activation effect on g-C ₃N ₄, and Rb atoms have a passivation effect on the surface of g-C ₃N ₄. At the same time, the adsorption of N ₂ molecules on M-g-C ₃N ₄ (M=Li, Na, K, Rb) is simulated, and the interaction mechanism between N ₂ molecules and alkali metals is understood. By analyzing the adsorption energy, structural parameters and electronic properties of N ₂ adsorption, it is found that the influence of Li and Na atoms on N ₂ adsorption is greater. The N—N bond of N ₂ is elongated, and the K and Rb atoms have little effect on N ₂. Alkali metal modified g-C ₃N ₄ is more beneficial for the adsorption of N ₂ molecules than pure g-C ₃N ₄, but as the atomic radius of the alkali metal increases, the adsorption capacity becomes weaker and weaker, and the electron transfer becomes less and less. That is to say, the ability of activating N ₂ molecule decreases in the order of Li, Na, K and Rb.

Using the threedimensional software ANSYS WorkBench for nonbeam pumping unit for dynamic analysis, the threedimensional finite element model of the pumping unit rack was established. To ensure that the system could be fully reflected in the dynamic analysis of the characteristics of its own force , firstly , the software prestress modal frame was used to analysis the pumping units static characteristic, and then the module was used on the rack's modal analysis, the rack's front nine natural frequencies and mode shapes were obtained. The results showed the Prestress had a little influence to the intrinsic characteristics of rack, and it could be neglected, and the rack structure affected the overall stability of the rack|through the analysis, changing the form and structure of the rack scantlings could improve the system's stability. Thereby the life of the rack was enhanced.

Through 3d ANSYS software, the belt pumping unit 3d model was established, the belt pumping unit structure was analyzed. Got the support maximum stress and displacement distribution maps, got some conclusion by analyzing the results. Based on this for the pumping unit for structure optimization design, three kinds of improved models was put forward, though the three kinds of models analysis, got the three models of the displacement and stress distribution maps. The results show that even the oil pumping unit design meet the requirements, it also can proceed the further optimization, changing the stress smaller angle stress model and raking prop, strengthen the main force position, not only greatly improve the stress state, but also make the structure more reasonable, economy applicable. 

Crude oil from Oilfield mined containing certain amount of water, so it need to be done oil - water separation that its moisture content reach requirements and will be on the market. Due to other methods having some shortcomings, physical separation is widely used. Spiral pipe separator has the character of simpler structure and lighter weight, becoming one of the most common centrifugal separation methods. Adapting computational fluid dynamics of VOF model, using the simulation software, oil - water separation of different inlet velocity in spiral pipe was simulated, and the oil - water separation rule was obtained. The farther from the axis, the speed is smaller and the lesser velocity the evener distribution. The most regional of water and phase distribution appeared in each lap nearly entry outside. Oil - water separation is in a cyclical along with the axial. It supplies spiral pipe separation and improvement provides with a theoretical.