For the problems of low efficiency and long computational time in the fluid-structure interaction of free-surface flow and elastic structure, an efficient fluid-structure coupling method for free surface flow was developed by combining the volume of fluid method with the fast dynamic mesh method based on the structure-pseudo elastomer. The free surface of the fluid was tracked by volume of fluid (VOF) method. The fluid domain was regarded as a pseudo elastomer, then the structure-pseudo elastomer system was constructed. The multiphase fluid force at the fluid-solid interface was used as the excitation to solve the dynamical equations of the system to obtain the structural vibration displacements and the mesh deformations of the flow field. The fluid flow, structural deformation and the dynamic mesh were solved sequentially at each time step to solve the fluid-structure interaction problem. Based on the developed method, the fluid-structure coupling response of elastic baffle under the impact of dam-breaking flow was calculated. The motion behaviors of the free liquid surface of water and elastic baffle were obtained. The results show that the free liquid surface evolution and elastic baffle vibrational displacements are well in agreement with those of the existing algorithm, under the same mesh size, the method can reduce the computational time by 33.3% compared with the existing algorithms, under the impact of water flow, the elastic baffle is bent slightly to the impact side. Then the water rises along the left side of the baffle and forms a jet, and the baffle is bent greatly to another side. Finally, the amplitude of the baffle gradually decreases due to the damping of the fluid on both sides.

Accurately identifying the connecting handle of the train coupler is of great significance for the operation of the uncoupling robot. A train connection handle target recognition algorithm based on improved YOLOv5 was proposed to address this issue. The C_switchable atrous convolution(C_SAC) module was integrated into the backbone feature extraction network, and the wise intersection over union(WIOU) function was introduced as a new bounding box loss function to enhance the feature extraction ability of the backbone network, improve the model’s generalization ability and convergence rate. Then, images of the connecting handles of train couplers in different environments and positions on the production site were collected for recognition. The experimental results show that the improved YOLOv5 algorithm achieves a target recognition rate of 96.6% for the connecting handles of train couplers. Compared with the original algorithm, it shows significant improvements in accuracy, recall, average accuracy, and other aspects. Finally, it was applied in the development of an automatic uncoupling robot for train carriages, greatly improving the accuracy and effectiveness of automatic uncoupling.

In order to effectively reduce the erosion and wear rate of ordinary elbows and extend their service life. A stomach-type elbow was proposed, based on the theory of gas-solid two-phase flow, the Fluent software was used on the stomach-type elbow to numerically simulate and analyze fluid erosion characteristics. The analysis results show that the second circular cross-section position less than 7.5°, greater than 25.0° less than 40.0° of the gastric bend has an erosion-resistant effect, in which the second circular cross-section position of 35.0° of the gastric bend erosion-resistant effect is the best, compared with the ordinary elbow erosion-resistant performance increase by 9.88%. The flow rate increases from 8 m/s to 28 m/s, and the maximum erosion rate of the gastric bend and ordinary elbow at 35.0°, 37.5°, 30.0° and 32.5° increases by 26.08 times on average. The particle diameter increases from 45 mm to 120 mm, and the maximum erosion rate increases by 1.71 times. The mass flow rate increases from 0.02 kg/s to 0.12 kg/s, and the maximum erosion rate increases by 7.35 times. Mass flow rate increases from 0.02 kg/s to 0.12 kg/s, the maximum erosion rate increases by 7.35 times. Regardless of the flow rate, particle diameter, mass flow rate, 35.0°, 37.5°, 30.0°, 32.5° of the maximum erosion rate of the gastric bend is always less than the maximum erosion rate of the ordinary elbow, that is, all have the effect of anti-erosion, of which 35.0° of the gastric bend on the whole has the best anti-erosion effect. The elbow can effectively reduce the rate of erosion and wear to extend the service life of the pipeline, but also for the elbow of the anti-erosion structure design and optimization to provide a new design scheme.

The problem of inaccurate evaluation of the clamping performance of the spiral angle type slip will be effectively overcome, which is caused by the unclear contact characteristics between the slip and the pipe string. The forces acting on the interaction between slip and columns were analyzed by the theoretical method. A full-scale finite element model of the interaction between the slip, pipe column, and slip seat was established using the numerical simulation method. The mises stress and contact stress distribution patterns of the slip and pipe column under different axial loads and friction coefficients were studied. The mises stress and contact stress gradually decreases from the bottom to the top in the axial direction. They are an imperfect symmetric distribution in the circumferential direction. And there are stress concentration locations. The slip is subjected to higher mises stress and lower contact stress than the pipe column. As the axial load increases, the mises and contact stress increase. As the friction coefficient increases, the mises and contact stress decrease. In design and practical use, emphasis should be placed on components and locations with high-stress levels. Under high load conditions, increasing the friction coefficient by changing the material and shape of the slip teeth is recommended. Further the clamping performance of the slip under high load conditions is improved. It also prevents damage to the pipe column caused by excessive clamping force. The research results can provide theoretical guidance for the design of slips and the evaluation of clamping performance.

In the process of oilfield development, the formation of emulsion between crude oil and water is quite common, which increases the difficulty of crude oil treatment. The composition of crude oil, especially the precipitation of paraffin wax, has significant influence on the stability of the emulsion. From the unique perspective that the oil composition affects the phase change and then further determines the emulsion stability, a systematic study was carried out with the methods of emulsion stability test, oil-water interfacial characteristic test, wax precipitation test, asphaltene dispersion stability test, and microscopic observation. It is observed that increasing the amount of liquid paraffin in the solvents leads to a change in the form of wax crystals from fine particles to larger agglomerated wax crystals, and the asphaltenes dispersion stability decreases along with it. Test temperature can significantly affect emulsion stability. At 30 ℃, increasing the percentage of liquid paraffin reduces the interfacial tension, increases the interfacial dilatational modulus, and enhances the structure of the interfacial film. This contributes to the formation of small droplets and improves emulsion stability to a certain extent. At 15 ℃, by contrast, increasing the liquid paraffin content promotes the development of a more structured wax crystals network, which significantly enhances emulsion stability by binding water droplets. Additionally, it is also found that a wax crystal interfacial film could be formed at the surface of the emulsified drops, which improves further the interfacial film strength and emulsion stability. Based on the above findings, an influencing mechanism model is presented concerning the synergistic stabilization of model oil emulsion containing asphaltene and paraffin wax.

The stability of power cyber physical system(CPS) is easily affected by stochastic uncertainty from both the information and physical sides. A stability analysis method for power CPS based on stochastic uncertainty model and a robust wide area feedback frequency control method were proposed. Taking into account the essential differences between the discreteness of the information side and the continuity of the physical side, as well as the mutual influence in terms of functionality, a dynamic model of power CPS in stochastic environment was established from both the information and physical sides. According to the definition of mean square exponential stability of stochastic differential equations, small signal stability analysis was conducted for dynamic model of power CPS. The critical variance based on mean square norm calculation was used to describe the impact of stochastic uncertainty on small signal stability of power CPS. Focusing on the norm optimization problem based on linear matrix inequality constraints, a robust wide area feedback controller was designed based on the distributed control method. Finally, simulation analysis was conducted on an IEEE 39 bus system, and the results verified the correctness and effectiveness of the proposed method.

Based on the reservoir conditions of tight conglomerate reservoirs in the Mahu area of the Junggar Basin, an experiment was conducted to study the interaction between tight conglomerates, CO₂, and water. The results indicate that after CO₂ dissolves in water to form carbonic acid, it primarily reacts chemically with feldspar and calcite in the cement between the conglomerate grains. This leads to significant around-grain dissolution, with dissolution being the main process and precipitation being secondary. Ultimately, this increases the porosity and permeability of the rock, enhancing the reservoir fluid seepage capacity. The maximum increases in porosity and permeability are 3.65% and 87.36%, respectively. Additionally, the surface roughness of the rock increases after the interaction, with hydrophilic mineral quartz exposed on the surface. The water-phase wetting contact angle of the rock decreases by 7.4°, enhancing hydrophilicity. The CO₂ huff and puff process has a positive effect on improving oil recovery, with the main oil-increasing mechanisms being the enlargement of pore space to enhance fluid seepage capacity and the improvement of rock water-phase wettability, which increases reservoir water-phase imbibition capacity and crude oil mobility, thereby improving oil recovery.

Transformer calibrators are a kind of equipment used to test the transformer error in the power system. With the development of technology, the transformer calibrator is also constantly innovating, from manual, and automatic to intelligent development, which has become a research hot spot. Two types of calibrators according to the usage method, namely the difference measurement method and the direct comparison method were introduced and the advantages and disadvantages of each method and related products were analyzed. Currently, digital calibrators had became a research hotspot because of their high degree of automation and multiple functions. The digital calibrator could be used for both conventional and non-conventional transformers, with a wide range of applications. Three key technologies that affect the accuracy of the digital calibrator are focused on by the paper. And a new technology based on small-signal on-site calibration were introduced, which had significant advantages over the current commonly used on-site calibration methods, with strong compatibility and high security, making the transformer calibration device smaller and more portable, and suitable for a wide range of occasions. Finally, it was pointed out that the transformer calibrator should continuously develop towards digitalization, intelligence, portability, accuracy improvement, and comprehensive performance improvement.

In order to improve the output performance of permanent magnet assisted synchronous reluctance motor (PMa-SynRM), a multi-objective optimization design method for external rotor PMa-SynRM based on kernel extreme learning machine (KELM) and fast non-dominated sorting genetic algorithm (NSGA-II) was proposed. Firstly, the preliminary design of the PMa-SynRM rotor magnetic barrier was carried out and the working principle of the PMa-SynRM was analyzed. Secondly, the influence of each design variable on the optimization goal was evaluated through comprehensive sensitivity analysis, and the main optimization parameters were selected. Thirdly, with high output torque, high efficiency and low torque ripple as the optimization goals, a surrogate model based on KELM was established. Finally, NSGA-II was used for global optimization, and the optimal solution was selected from the Pareto frontier generated by NSGA-II, which was verified by finite element analysis. The simulation results show that the average torque of the optimized motor is increased by 15.83%, the torque ripple is reduced by 60.27%, and the efficiency of the optimized motor is also improved compared with the initial motor, which verifies the effectiveness of the optimized design method proposed in this paper.

The vibration excitation transmission of the platform should be suppressed while ensuring the safe and reliable operation of equipment. Currently, most research on vibration reduction focuses on individual pedestals or pedestal-platform plate structures, with few studies comprehensively considering the relationship between equipment, pedestal, and platform bottom plate vibrations. ultra-deep water semi-submersible drilling platform equipment’s long base was taken as the research object and impedance analysis and optimization design technology was utilized to control input power flow of the platform bottom plate in key frequency bands. Design variables such as mass and stiffness were optimized to improve base plate thickness while maintaining support strength and stiffness. A coupling vibration control model for “equipment-pedestal-platform” was established, using a particle swarm optimization algorithm with linear weight decline for optimization. Finite element method verification results show that this technical process is feasible, reducing optimized input power flow by 95.43% in low frequencies below 300 Hz and decreasing total response level of vibration acceleration by 18.1 dB.