The drilling process requires real-time measurement of drill string vibration, which is crucial for drilling and downhole safety. However, the traditional power supply mode used for downhole vibration sensors has been found to increase drilling costs and reduce drilling efficiency. Therefore, sensors with self-powered capabilities are considered more suitable for practical conditions. A downhole arrayed self-powered deformable vibration sensor was proposed based on the principle of triboelectric nanogenerators. Experimental results demonstrate that the sensor synchronized measurements of amplitude and frequency. The vibration frequency is measured within a range of 0 Hz to 11 Hz, with a measurement error of less than ±4%. Additionally, the sensor is able to measure three discrete amplitude values (10, 25, 40 mm) with a measurement error of ±3 mm. The sensor can working normally within a temperature range of 0 ℃ to 85 ℃. Furthermore, the sensor has power generation capabilities, with experiments revealing a maximum output power of 8.3×10^-7 W. Notably, when multiple sensors are used in parallel, the power generation capacity is significantly enhanced. These research findings provide new insights for the development of downhole sensors and downhole generators.

Continuum robots have been widely used in natural cavity intervention therapy, but the current flexible continuum robots have poor positioning accuracy and lack of accurate navigation means. In response, a multi-segment continuum robot shape reconstruction method based on electromagnetic positioning information was proposed, aimed at achieving accurate end navigation and positioning. An efficient two-stage active structure shape reconstruction method based on third-order Bessel curve was proposed. The solution of Bessel curve was optimized to nonlinear least squares problem, which was solved quickly and accurately by particle swarm algorithm with linear decreasing weights. The proposed method can accurately fit the shape of the two-segment continuum and has good real-time performance. The results show that within the bending angle process, the average root-mean-square error of shape reconstruction is 0.48 mm, which is 0.8% of the length of the continuum bending segment. The accuracy and reliability of the proposed shape reconstruction method for intracavitary interventions using micro-continuum robots are demonstrated through detailed modeling and validation results.

Based on Monte Carlo method, Python and Abaqus interface were used for secondary development, and an interfacial transition zone was generated to distinguish between natural coarse aggregates and new and old interfacial transition zone(ITZ) and recycled aggregate concrete (RAC) 2D meso-five phase model of new and old mortar. An improved moisture-chloride ion coupling model under dry-wet cycles was proposed, and the computational results of this model were compared and validated against physical experiments, with good agreement. This model was then applied to analyze the effects of dry-wet cycle periods, ITZ permeability, water-cement ratio, and natural aggregate volume fraction on chloride ion transport properties. The numerical results show that as the number of dry-wet cycles increases, the diffusion depth and concentration of chloride ions in RAC also increases. When the ratio of ITZ diffusion coefficient to the new mortar diffusion coefficient increases, the chloride ion concentration in the diffusion region increases significantly, especially at the front end of the diffusion zone. In addition, there is a positive correlation between RAC materials with different water-cement ratios and chloride ion transport capacity, with little variation in chloride ion transport performance within the high water-cement ratio range. Finally, the volume fraction of recycled aggregates has a significant impact on the chloride ion permeability of RAC, indicating that the ITZ and new and old mortar have an important influence on the transport of chloride ions.

In order to study the prevention and control of power disaster induced by coal mining process, Brazilian splitting test of raw coal specimen was carried out to study the energy evolution law in the process of coal body tensile damage destruction, and the precursor information of coal body destabilization and destruction was identified. The results show that the coal body tensile damage process has significant nonlinear evolution characteristics, and it is possible to identify the critical point, destabilization point, and damage point of coal body damage. The energy evolution characteristics of coal body tensile damage in each stage are significantly different. In the elastic deformation stage, the input energy is mainly converted into elastic energy, and the dissipation energy remains stable, while in the destabilization stage, the dissipation-elasticity ratio shows a jumping growth. By calculating the energy release rate and energy dissipation rate, it is found that the index has abnormal response characteristics at the critical point, destabilization point and damage point of the coal body tensile process, and the appearance of the characteristic points all have significant precursor information. The nature of coal destabilization is the result of energy accumulation and dissipation, and the energy index of coal body can reveal the abnormal characteristics of energy evolution in the process of damage and destruction of the specimen, and identify the precursor information of coal body catastrophe, which is conducive to the over-warning, and escort for the safe mining of coal.

The pore structure of deep tight sandstone reservoir is complex and heterogeneous, and it is difficult to determine the influencing factors of pore microscopic parameters on the characteristics of gas-water phase permeability. Based on the fractal geometry theory, combined with the core mercury intrusion porosimetry (MIP) method, nuclear magnetic resonance (NMR) T₂ spectroscopy test and micron CT scanning results, the micro-pore throat parameters and various scale fractal dimensions of the reservoir were obtained. Through the mobile gas porosity and the maximum atmospheric phase relative permeability, the control mechanism of the fractal dimension and micro-pore throat structure parameters on the gas-water phase permeability characteristics was discussed. The results show that mercury injection and NMR fractal curves have obvious “three-stage” characteristics, and the total shape dimension of the reservoir describes the distribution of seepage and movable fluid more accurately when gas and water coexist. The maximum mercury saturation, average pore throat radius, total reservoir shape dimension and displacement pressure have significant effects on the mobile gas porosity during gas seepage. The average pore throat radius has a significant influence on the maximum effective gas phase relative permeability in gas seepage. The control mechanism of the micro-pore structure on the gas-water phase permeability can provide a powerful guide for the efficient development of water-producing gas reservoirs.

At present, the performance of the traditional centralized coil antenna used for radio frequency identification(RFID) detection and localization of underground cables is insufficient, which seriously restricts the improvement of its detection and localization distance. A new type of high field strength distributed RFID coil antenna structure was proposed. Based on the derivation of antenna related electrical parameters, the magnetic field strength of the coil antenna was taken as the objective function, and its quality factor was fixed as the constraint condition. Particle swarm optimization algorithm was employed to optimize the number of turns of the coil antenna and the turn spacing between adjacent two turns. Finally, an experimental test platform was built. The test results show that compared with the traditional centralized RFID coil antenna, the distributed RFID coil antenna increases the reading distance by 33.3%, significantly enhances the received signal strength indicator (RSSI) at the same distance, and helps to improve the accuracy of the underground RFID localization method based on RSSI, which provides an important reference for the application of RFID detection and localization of underground cables.

In order to study the solution properties of polyacrylamide at high temperatures at the molecular-atomic scale, the molecular models of partially hydrolyzed polyacrylamide(HPAM) and AM/AANa/AMPSNa copolymer [P(AM/AANa/AMPSNa)] have been established through a combination of experimental methods and molecular dynamics simulations. The solution properties of the two polymers at elevated temperatures were systematically investigated in terms of polymer chain rigidity and flexibility, hydrogen bonding, hydration layer, interaction energy and the effect of salt cation, and the micro-mechanism of temperature resistance of P(AM/AANa/AMPSNa) was explained. The results show that the introduction of side chains containing methyl and sulfonated groups into the molecular chain of P(AM/AANa/AMPSNa) could increase the rigidity of the molecular chain, more hydrogen bonds are formed between sulfonated groups and water and has longer lifetime. At the same time, the strong polar sulfonic acid group makes the hydration layer denser, which results in the weaker static shielding effect of the cations on the P(AM/AANa/AMPSNa). Under different temperature conditions, P(AM/AANa/AMPSNa) has stronger intermolecular non-bonding interactions, stronger water retention effect of the molecular chain at the microscopic level, and higher viscosity at the macroscopic level.

In order to explore the impact of the number of bearing plates on the bearing capacity of the expanded pile and the soil around the pile, a small half face pile model test equipment developed was used to record the deformation of the soil around the pile in real-time using using digital image correlation (DIC) technology equipment, and to analyze the displacement and failure characteristics of the soil around the pile. Experimental research shows that during loading, the soil under the load-bearing plate is compressed to form a compression zone, and the influence range of this zone gradually increases with the increase of load, while squeezing towards the soil on both sides. The cracks above the bearing plate continue to develop until a free zone is formed, and this area expands with the increase of load. The bearing capacity of three plate piles has been significantly improved compared to single plate piles and two plate piles, but their load-settlement curve shapes are relatively similar. During the loading process, the displacement changes of the soil around the pile near and below the bearing plate are the most significant. Therefore, the study supplements the research on the impact of the number of bearing plates on the soil around piles and other related directions.

Based on the sand-mud interlayer core of a block in Ordos Basin, denoising neural network based on wavelet transformation (DWTNet) was used to denoise the core image. The evaluation of this method was carried out by comparing the peak signal-to-noise ratio (PSNR) and the post-denoising image outcomes. The investigation reveals that by applying the DWTNet denoising algorithm to the test sets YX1 and YX2, and contrasting it with other denoising algorithms such as EGDNet, the PSNR values at noise levels of 25, 50, and 75 dB are respectively 0.527, 0.418, and 1.1 dB higher than those achieved by the EGDNet algorithm. The proposed algorithm surpasses others in terms of metrics including peak signal to noise ratio(PSNR), and visually, the resulting images processed by it exhibit enhanced clarity. The introduction of this method holds substantial significance for the calculation of parameters like porosity, mean specific surface area, mean curvature, among other rock properties, thereby advancing the capabilities in digital core technology, CT scanning analysis, and understanding of rock characteristics.

The magnetic flux leakage detection technology has been widely used in the field of ferromagnetic material defect detection, in which the magnetic dipole method is currently the most widely used mathematical method for predicting magnetic flux leakage from structural defects. The magnetic dipole method is primarily employed for predicting the magnetic flux leakage signal of regular defects. The unit magnetic dipole band superposition model can be used to predict the magnetic flux leakage signal of complex defects. The magnetic charge density of complex defects needs to be calculated when the model is used for prediction. However, the magnetic charge density distribution of complex defects is inhomogeneous, and the calculation is complex. Therefore, a calculation method of discrete magnetic charge density field was proposed for calculating the magnetic charge density of three-dimensional irregular defects. The computational complexity of the model was reduced by using this method and the magnetic flux leakage signal of three-dimensional irregular defects can be quickly and exactly obtained. Comparison between the signal predicted by the unit magnetic dipole band superposition model based on discrete magnetic charge density field and the signal simulated by COMSOL software demonstrates the feasibility of the method. Experimental results show that the prediction performance of the model has been significantly improved by using this method, the maximum prediction error is reduced by 90.08%, and the calculation time is reduced by 97.43%, thus a fast and effective solution for the calculation of the magnetic charge distribution of three-dimensional irregular defects is provided.