The Ordos Basin's marine carbonate reservoirs often experience downhole complexities such as gas invasion, lost circulation, and borehole collapse during drilling. It is particularly important to systematically evaluate the overpressure mechanisms and accurately predict formation pressure for the exploration and development of the target strata. The carbonate reservoir of the Ordovician Majiagou Formation in the eastern Ordos Basin was selected as the research target. Overpressure mechanisms were analyzed using the combination of well log curve analysis, effective stress-acoustic velocity method, acoustic velocity-density method, and comprehensive analysis method. A physical model of elastic modulus for carbonate rock matrix, framework, mixed pore fluid, and saturated fluid rock was established, and combined with the effective stress principle, a method for predicting formation pressure was developed, applicable to the Majiagou Formation in the eastern Ordos Basin. Finally, the model's accuracy was verified using field data. The results indicate that hydrocarbon generation is the primary cause of overpressure in the target reservoir, with undercompaction and structural compression as secondary factors. The new model achieves a relative error of less than 10%, demonstrating strong applicability and high predictive accuracy. The research results provide guidance for the study of hydrocarbon accumulation in the Majiagou Formation in the eastern Ordos Basin.

The pore structure is a pivotal determinant of the physical properties of tight sandstone reservoirs, and elucidating its characteristics holds great significance for oil and gas exploration and development. Taking the 4th member of the Xujiahe Formation tight sandstone reservoirs in Tianfu Gas Area as an example, the pore structure characteristics, fractal features, and fluid mobility of the Xu-4 sandstone in the study area were systematically analyzed through thin section identification, scanning electron microscopy observation, nuclear magnetic resonance testing, high-pressure mercury intrusion testing, and X-ray diffraction experiments, combined with fractal theory. The results indicate that the sandstones of the 4th member of the Xujiahe Formation in the study area are predominantly composed of feldspar lithic sandstone, belonging to an ultra-low pore-ultra-low permeability pore type reservoir. The pore type is primarily feldspar-dissolved pores, and the throat type is predominantly sheet throats. According to the morphology of the high-pressure mercury injection curves and nuclear magnetic resonance outcomes, the pore structure of the 4th member of the Xujiahe tight sandstone reservoir is categorized into three distinct types. Among them, the material properties of the I-type samples are the best, with larger pore-throat radii, good connectivity and sorting of pore-throat, strong fluid mobility, and the best reservoir quality. The pore structure and fluid mobility of the fourth member of the Xujiahe tight sandstone reservoir are affected by sedimentary structures and mineral content. Specifically, reservoirs with coarser grain sizes and better sorting demonstrate superior pore structure and fluid mobility. Furthermore, quartz, the primary rigid mineral in sandstones, exhibits resistance to compaction, thereby safeguarding the reservoir pores to a certain extent. However, calcite and clay minerals will occupy pore space, resulting in deterioration of the pore structure and fluid mobility of the reservoir.

Under the traditional design scheme, the design quantity of main girder of the bridge erector is redundant and there are many consumables, which will reduce the production efficiency, and the existing optimization methods have the problem of low convergence accuracy. An enhanced beluga whale optimization (EBWO) based on quadratic interpolation strategy was proposed, and lightweight design of main girder of the 600t bridge erector was carried out. Firstly, six test functions were applied to evaluate and compare the effectiveness of the beluga whale optimization (BWO), EBWO and three other prevalent optimization algorithms, focusing on their convergence characteristics. Then, a mechanical analysis was conducted on the bridge erector girder under the real loading conditions. An optimization model was established by combining bridge girder design specifications and mechanical requirements, and the cross-sectional area optimization of main girder of the bridge erector was carried out. The results show that EBWO has the enhanced stability and convergence characteristics. It is proved that the optimized main girder is reduced by 19.3%, and can meet the safety requirements.

The disruption recovery is regarded as a crucial role in the operation of freighter airlines. To expand the application scenarios of the freight flight network, elements such as mandatory nodes and external arcs were introduced to enhance the applicability of the network. In general, aircraft and cargo were defined in separate networks and are recovered using a sequential solving method. To explore the correlation between each research object and to complete each recovery action, the entity flow was defined to integrate different types of entities in the same network. To solve the problem of crew recovery, constraints such as crew duty and flight qualifications were added to the model, and a mixed integer linear programming model was constructed based on an improved flight network. This model can achieve integrated recovery of aircraft, cargo, and crew. To accurately evaluate the capacity constraints of the cargo aircraft, a unit load device was used to represent the volume of cargo and to improve the relevant models of capacity constraints. An entity aggregation approach was employed to reduce the number of entities to control the model complexity. The model evaluation was performed using operational data provided by a small freighter airline. The results show that the recovery solution causes a 42% reduction in the delay time. In the subsequent simulation experiments, six different disruption scenarios were established for two freighter airlines with multiple fleets. As the disruption rate increases, medium freighter airlines adopt the strategy of re-routing aircraft and rescheduling crew, while large freighter airlines focus on flight delays. The proposed integrated air cargo schedule recovery model based on an improved flight network can solve all the cases exactly in limited time, and the average error is 0.47%.

In order to improve the accuracy of in-camera parameter calibration and reduce the error caused by inaccurate estimation of corner coordinates, a subpixel iterative corner optimization algorithm was proposed. By modeling the camera image, integrating the distortion mathematical model, and using the subpixel iterative algorithm, the gradient value changes of points in the search window were calculated and the corner coordinates were iteratively optimized to provide more accurate initial values for calibration. Combining with the optimized corner coordinates, Zhang's calibration method was used to solve the internal parameters, and the influence of corner points on the acquisition of diagonal points and camera calibration was discussed through experiments. The calibration accuracy was characterized by reprojection error, and the effectiveness of the iterative algorithm was tested. The experimental results show that the algorithm can effectively improve the accuracy of corner acquisition and the calibration accuracy of camera parameters by using fewer iterations.

In order to realize the optimal design of rock-socketed pile foundation in mountainous area and effectively prevent the rupture of the rock, the compression mechanical behaviors and failure mechanisms of brittle rocks with different lithologies were experimentally and numerically investigated. Firstly, uniaxial compression tests were carried out on five kinds of brittle rocks based on the self-made compression testing system. Acoustic emission (AE) monitor system and digital image correlation (DIC) technology were used to discuss the characteristic parameters of AE signals during the crushing. Moreover, the characteristics of critical failure precursors and the evolution rules of damage failure of different rocks were obtained by using the nonlinear explicit finite element (FE) method. The experimental results were in good agreement with the corresponding FE ones. The results show that there are the obvious AE phenomena in brittle rocks during the uniaxial compression test, and the active degree of ringing count and accumulated energy can describe the internal damage of the specimens effectively. At the initial stage of the compression, there is no obvious crack on the rock surface. However, more cracks appear on the surface of the specimens with the increase of the compressive stress. The specimens are destroyed instantaneously when the compressive stress reaches the peak stress, and no new cracks are generated. The distribution and evolution of local strains can intuitively predict the breeding and expansion of new fissures. The research results provide theoretical reference for monitoring and warning of rock failure and foundation design of transmission line in mountainous area.

The traditional steady-state visual evoked potential (SSVEP) brain computer interface system usually uses a small number of frequencies for encoding, resulting in a limited number of encodings to dozens, which cannot meet the demands of environmental tasks with a large number of instructions. To address this issue, a Hamming distance multi frequency code (HDMFC) paradigm and corresponding recognition algorithm based on Hamming distance were proposed. The Hamming distance was combined with stimulus paradigm encoding and signal recognition algorithms to encode 120 instructions using 8 frequency signals. Data collection and classification experiments were conducted on 7 subjects. The results show that the accuracy of the 120 encoding online experiment based on Hamming distance can reach 90.60%. The research results provide an effective method for increasing the number of SSVEP paradigm codes and improving classification performance, verifying the practicality and effectiveness of Hamming distance in this field.

In order to compare the clinical effect of different surgical technique of ligamentum flavum in percutaneous endoscopic interlaminar lumbar discectomy. From March 2015 to March 2019, 86 cases of L₅-S₁ lumbar disc herniation (LDH) were analyzed retrospectively. According to the different treatment of ligamentum flavum during operation, the patients were divided into control group (n=55) and modified group (n=31). The age, gender, course of disease, duration of surgery, intraoperative bleeding, hospital stay, and surgical related complications between the two groups of patients were analyzed and compared. One month, three months and six months after the operation, the routine outpatient reexamination and follow-up were carried out. Numerical rating scale(NRS) and modified macnab were used to evaluate the effect of operation. SPSS 19.0 was used to process the data. Mean±SD was used for measurement data. Comparison between groups using independent sample t-test, and analysis of variance of repeated measurement data was used for the NRS score comparison before and after operation. The counting data were expressed in percentage, Fisher exact test or χ² test were used for comparison between groups, and Mann Whitney rank sum test was used for comparison of follow-up time and grade grouping data between groups. The results show that the postoperative pain score of both groups decrease significantly(overall variance within the group F_within=197.477, P=0.001). There is no difference between the two groups (inter group overall variance value F_interg=1.701, P=0.203).The time factor has no effect on the results of the two groups(Interaction effect value F_inter=2.231, P=0.108). The NRS score of the modified group is significantly lower than that of the control group (t=2.086, P=0.046). According to modified Macnab criteria, there is no significant difference between the two groups (distribution of postoperative outcomes U=782.000, P=0.308). It is concluded that the modifiedsurgical technique of ligamentum flavum in the PEILD will not prolong the operation time or increase the amount of bleeding. While removing the herniated intervertebral disc, it can preserve the integrity of the relevant tissue structure, achieve satisfied clinical effect, and conforms to the core concept of minimally invasive surgery.

With the transformation of the modern power system, the application of grid-connected inverters is increasing, and the transient synchronization stability of inverters after disturbance is becoming prominent. Previous research on transient synchronization stability mainly focuses on the dynamic of the phase-locked loop, with less consideration of the impact of outer loop control, resulting in a cognitive bottleneck in understanding transient synchronization mechanism. To address these issues, the grid-following voltage source inverter system was modelled, taking into account the inverter control strategy and limiting elements in detail. Subsequently, the impact of different voltage drops on the stability region of the equilibrium point was analyzed, and the effects of outer loop control proportional integral (PI) and limiting elements on transient synchronization were discussed. The influence mechanism of outer loop control on the transient synchronization stability of inverters was revealed systematically. Finally, the effectiveness of the proposed theory was verified in PSCAD/EMTDC.

In response to the challenges of low efficiency, high cost, and difficulty in deployment on mobile devices in current road damage detection technology, a novel road crack detection method based on the improved YOLOv8 algorithm, named YOLOv8 road crack (YOLOv8-RC), was proposed. The C2f module, based on the YOLOv8n architecture, was enhanced through the introduction of dynamic snake convolution technology, which more accurately identified tubular structural features and adaptively focuses on fine and curved local structures. Furthermore, a highly efficient multi-scale attention(EMA) mechanism was incorporated into the algorithm, effectively enhancing recognition accuracy. In the neck structure of the model, a weighted bidirectional pyramid network(BiFPN) was added to achieve multi-scale fusion of features, thereby optimizing both the accuracy and efficiency of the algorithm. Experimental results on the RDD2022-China-MotorBike and RDD2022-Japan datasets demonstrate that the improved YOLOv8n-RC model achieves mAP50 scores of 78.8% and 43.8%, respectively, representing improvements of 3.9% and 3% over the original YOLOv8n model. The total number of model parameters for the proposed algorithm is only 2.84 M, and the computational complexity is 7.8 G, underscoring the practicality and superiority of this method.