In order to study the effect of different scanning strategies on laser deposition of nickel-based alloy matrix, the process of deposition of IN718 alloy powder on IN718 alloy matrix under four different scanning strategies was numerically simulated by ABAQUS software, and tested under the same conditions. The heat source verification results show that the heat source model is accurate and effective, and the numerical simulation process accords with the actual deposition process. The analysis results of temperature field, stress field and deformation field show that the thermal influence of different side scanning is less than that of same side scanning and reciprocating scanning is lower than that of unidirectional scanning, and the peak temperature is lower, thus the residual stress is lower, and the deformation degree of the matrix can be effectively reduced. The experimental results show that the numerical simulation process is accurate and effective. It is concluded that the residual stress value and deformation can be reduced effectively by using the reciprocating scanning method on different sides.

The general acidification technology of horizontal wells provides a simple and important method of stimulation for carbonate gas reservoirs. The common acidization methods were divided into two major categories: matrix acidification and fracturing acidification. To determine the best stimulation method of horizontal wells between acid fracturing and matrix acidizing, it is significant to achieve the efficient exploitation of reservoirs and optimization of process program. A dimensionless gas production index formula was obtained for horizontal well acidizing in carbonate gas reservoir. Also, a carbonate-acid-stimulation coefficient model was established to optimize the general method of acidification for the horizontal wells in carbonate gas reservoirs. Then, the influence of geological and engineering factors on the acidization increase coefficient was analyzed. Finally, field verification and application were conducted. The conclusions are as follows. When the carbonate-acid-stimulation coefficient R_JH>1, the productivity of matrix acidizing wells exceeds that of fractured acidizing wells. When R_JH<1, the productivity of fractured acidizing wells is higher compared to matrix acidizing wells. A higher permeability anisotropy coefficient increases, the number of fracturing fractures and the amount of acid fluid, but reduces the carbonate-acid-stimulation coefficient. The increase in porosity and horizontal length lead, to a higher carbonate-acid-stimulation coefficient. When the porosity of the gas reservoir falls below 7.3%, the productivity of the fractured acidizing well is improved. When the length of the horizontal section is 500 m and the number of fracturing fractures exceeds 4, the carbonate-acid-stimulation coefficient R_JH<1, and the productivity of the fractured acidizing well is improved. When the total volume of acid solution injected is 600 m³, the productivity of fractured acidizing well reaches a higher level than when the acid-solution volumetric dissolving power X>0.08.As verified in the carbonate reservoirs located in the northeastern Sichuan block, the production increase effect produced by using the carbonate-acid-stimulation coefficient method is significant after process optimization. Therefore, a theoretical guidance is provided in this paper for optimizing the acidification method of horizontal wells in carbonate gas reservoirs.

CO₂ flooding technology, recognized as a mature tertiary recovery method, is widely applied in complex small fault-block oilfields with strong heterogeneity. However, severe gas channeling is commonly observed during CO₂ flooding. As a result, the improvement in oil displacement efficiency remains low, typically below 10%. To address this, effective methods were explored to enhance oil displacement efficiency. Foam profile control and plugging were utilized as key techniques to achieve this enhancement.In the experiment, the JS oilfield was used as an example. The foam performance of the gas-soluble foaming plugging agent G-CF4 and the water-soluble foaming plugging agent W-CF1 was compared. The plugging agent with better foam performance was selected. Its plugging ability and oil displacement efficiency were tested.The results show that under target reservoir conditions, the optimal foaming plugging agent is 0.25% G-CF4.Moreover, the greater the permeability difference within the core combination, the stronger the plugging effect of G-CF4 in high-permeability cores.For a core combination with a permeability difference of 88 mD, the resistance coefficient of high-permeability cores is 2.5 times higher than that of a core combination with a permeability difference of 50 mD. In the core combination with 88 mD permeability difference, G-CF4 can maintain the resistance coefficient of high permeability cores above 9.2.The injection of 0.25% G-CF4 solution for 0.3 PV, followed by CO₂ flooding, improves oil displacement efficiency by 15% compared to CO₂ flooding alone.This study provides laboratory evidence supporting the optimization of foaming plugging technology in the JS oilfield.

The performance of supercritical multi-thermal fluid injection in heavy oil reservoirs is markedly superior to that of steam flooding. However, the underground seepage law of injecting supercritical multi-thermal fluid is not yet clear. Therefore, the “high-temperature and high-pressure steady-state method” was proposed to test the oil-water and oil-gas relative permeability curves at different temperatures. The viscosity of produced heavy oil and the contact angle between oil sand and water at different temperatures were tested, and finally, combined with the oil-water, oil-gas relative permeability and Stone-Ⅱ prediction model, the isoperms of oil phase relative permeability in different hot areas during three-phase seepage were obtained. The results show that after the action of supercritical water on heavy oil, the measured viscosity of produced heavy oil decreased by 31.03% at 50 ℃ compared to steam, and the contact angle between oil sand and water decreased from 139.5° to 100.9°, indicating that the wetting properties of the oil sand develop towards a water-wet direction. Compared with the relative permeability of oil phase, the relative permeability of water phase is very small, and the characteristic value of oil-water relative permeability curve changes gradually and then suddenly at supercritical temperature. The relative permeability of oil-gas increases gradually with the increase of temperature. In the isoperms of oil phase relative permeability, the area of the oil flow zone expanded as temperatures rose, and under supercritical conditions, the flow zone area grew to 54.59%, highlighting a significant enhancement in oil-phase flow capacity. The research results of this paper can provide theoretical basis for the seepage mechanism and numerical simulation of supercritical multi-thermal fluid injected in heavy oil reservoirs.

As a power drilling tool that can meet the needs of deep ground and high temperature drilling, the short life of thrust bearing is a key problem affecting drilling efficiency. Based on the CCD design method and finite element numerical simulation method, three sets of variables were selected as the design parameters, the orthogonal test between different structural parameters and abrasive wear life was carried out, and the optimal structural parameters of the bearing were determined by the range analysis method. The temperature-displacement coupling finite element model of bearing wear was established, and the influence of axial load, temperature and wear times on the wear depth of the bearing was studied considering the frictional heat generation of the bearing. The results show that the overall performance of the bearing with optimal structural parameters is improved, the stress concentration of the bearing is alleviated, the wear of the bearing is reduced, and the optimized structural life is increased by 4.6% compared with the initial life. This research method provides a reference value for the optimal design of this type of bearing. At the same time, the influence of different working conditions on bearing wear was analyzed. With the increase of axial load, the wear depth of the bearing increases. With the increase of the number of wear, the wear depth also shows an increasing trend. With the increase of bottom hole temperature, the wear depth decreases first and then increases gradually.

Filling phase change capsules in a container to form a packed bed heat storage unit is a typical applica-tion of phase change capsules. Phase change capsules are usually stacked in a specific layout in the packed bed flow channel. Studying the heat storage and release characteristics of a single phase change capsule in a packed bed flow channel can help optimize the design of a medium-temperature phase change heat storage system. Therefore, a two-dimensional packed bed numerical model of phase change cap-sules was established. The heat transfer and flow characteristics of the external heat transfer fluid flowing through the phase change capsules in the direction of gravity, counter gravity and vertical gravity were compared and studied. The effects of flow rate, temperature and capsule diameter on the melting process of phase change capsules were studied. The results show that the heat transfer rate of the windward side of the phase change capsule in the packed bed channel is faster. Due to the thermal resistance of the cavity air and the natural convection, the complete solidification time is the shortest when the heat transfer fluid flows countercurrently. Compared with the downstream flow, the complete solidification time of the up-stream flow is shortened by 8.9%. When the diameter of the phase change capsule is 12 mm, the melting speed of the phase change capsule with PTFE as the wall material in the center is 1.45% slower than that of the 304 stainless steel phase change capsule, and the average heat storage rate is 1.5% lower. The melting rate of the phase change capsule with modified PTFE as the wall material cavity in the center is 6.9% faster than that of the 304 stainless steel phase change capsule, and the average heat storage rate is 5.8% higher. Increasing the HTF inlet velocity and temperature can increase the average heat storage rate of the phase change capsule and shorten the melting time of the phase change capsule. The heat storage and release characteristics of the capsule have important guiding significance for the design optimization and practical application of the capsule monomer and the medium temperature phase change heat storage system.

Small sensors powered by wind-solar hybrid power supply do not require regular replacement of the power supply, and can be deployed in various remote areas. However, in practice, the photovoltaic panels are prone to accumulation of dirt, resulting in reduced power generation, and the rotating parts of small wind turbines are also very prone to failure. A wind-solar hybrid power device with a simple structure and self-cleaning capability was designed, and its solar and wind energy collection performance was experimentally evaluated based on meteorological statistical data. Moreover, the vibration cleaning efficacy of the photovoltaic panels under various dust coverage levels was compared. The research results show that the device can generate a maximum output power of 77.28 mW under simulated clear weather conditions (light intensity of 948.1 W/m²). The starting wind speed of wind energy collection based on piezoelectric and vortex-induced vibration effects is around 1.5 m/s, and a wind speed of 4.3 m/s in the experiments can generate an output power of 4.63 mW. After vortex-induced vibration cleaning of the photovoltaic module with different dust coverage densities, the output power of solar energy collection can be restored to over 84% of the clean state. This study presents a new technical solution for maintenance-free small-scale micro power generation equipment in remote areas.

It is essential to perform equipment reliability classification in order to devote limited resources to NPP equipment management reasonably, improve equipment reliability and availability while reducing maintenance workload and cost, and enable NPP’s safe, reliable, and economical operation. In light of engineering characteristics of the demonstration fast reactor and the challenges during the construction, an attainable new method was developed to standardize the process of equipment reliability classification and complete the classification of all systems. The differences and characteristics among the methods were compared, the implementation process of the new method was proposed and demonstrated with two real systems. The application shows that the proposed method is efficient, effective and rational, hence can offer to assist other NPPs of similar reactors to implement reliability classification during NPP construction.

Aiming at the problems of poor disturbance immunity and long dynamic response time of the grid-connected inverter based on VSG(virtual synchronous generator) control, an improved fuzzy adaptive control strategy for VSG was proposed. First, a small-signal model of VSG was established to analyze the effects of virtual inertia and damping coefficient on the dynamic response of the system. Determine the value range of the two parameters and use the sparrow search algorithm to optimize the initial values of inertia and damping in the adaptive strategy. Next, the angular frequency change curve of the system after perturbation was analyzed to refine the design fuzzy rules. Finally, a stand-alone VSG model was built in MATLAB/Simulink to compare the different control strategies. The results show that the fuzzy adaptive strategy proposed in this paper not only improves the response speed of the system, but also has a strong anti-disturbance ability when the command power and load power change suddenly. The effectiveness of this paper's strategy is proved.

A novel clustering approach combining Kmeans++ and PAM was introduced to segment the daily load curve chronologically for the dynamic reconfiguration of distribution networks incorporating time-varying wind solar power and loads. Multi-objective dynamic reconfiguration model of distribution network based on the optimal objectives of comprehensive cost, voltage offset and load balance. To enhance the computational efficiency of the model, an INOA(improved Nutcracker optimization algorithm) was proposed, which used Tent mapping+quasi-reflection learning to provide high-quality initial population. Dynamic fitness-distance balance selection method and tangential flight strategy were introduced to enhance the global search capability. The Cauchy-Gaussian variation perturbation was incorporated to augment the algorithm’s capability to escape from local optima. Using the IEEE 33-node system as a basis, the outcomes indicate that the suggested approach effectively achieves optimal load distribution and efficiently addresses the restructured model.