To further meet the plasma heating requirements of EAST (experimental advanced superconducting tokamak) device, NBI (neutral beam injection) system requires higher beam power. Accordingly, the EAST NBI laboratory has developed a 120 keV accelerator for this purpose. The analysis of the whole accelerator needs to be carried out from various perspectives such as beam optics, insulation support, active cooling and materials. Taking into account factors such as plasma parameters, electrostatic lens, voltage resistance between grids, and assembly errors, the numerical simulation program was utilized to beam optics analysis for the slit tetrode ion source accelerator. Beam trajectory, electric field strength distribution, and beam divergence angle were investigated and optimized to preliminarily determine the grid parameters of the new multi-slit accelerator. The accelerator obtains the beam with the minimum divergence angle of 0.6° in the vertical direction with perveance of 1.52 μp, meeting the design criteria for beam current intensity of 60 A and divergence angle below 1° of the ion source.

For the motion control of four-rotor UAV in attitude, the main method is the application of ADRC (active disturbance rejection control) system. For this system to deal with the complex interference with sensor noise, the previous fal function design still has many defects in application. Under the function of traditional fal function, the ESO(extended state observer) has the problems of insufficient observation accuracy and high chattering rate. Therefore, a new nonlinear smooth tfal function was improved on the basis of the previous fal function, and ESO was studied with this function. Finally, other ADRC methods were compared with this method in MATLAB/Simulink software, and the newly designed tfal function shows better convergence. The new ESO based on tfal design has obvious improvement in error estimation and error following performance. At the same time, compared with the improved function galn and the traditional function fal, the tracking capability of the new ESO attitude active disturbance rejection control system is improved by 2.3% and 4% respectively, and the anti-interference performance is improved by 50% and 67% respectively.

The Sichuan Basin, situated in the heart of China, is renowned for its abundant oil and gas reserves within a geologically intricate sedimentary basin. A multitude of strike-slip faults, characterized by their extensive reach, substantial scale, and modest displacement, are particularly prominent in the basin’s central region. In order to elucidate the influence of these faults on the formation of oil and gas reservoirs, high-precision seismic data analysis and numerical simulation techniques were used to investigate the strike-slip fault system in the central Sichuan area. The results show that the primary strike-slip faults in the central Sichuan region bifurcate into two distinct orientations: nearly EW(east-west) and NE(northeast-southwest). These first-order faults are inclined to emerge along the peripheries of secondary tectonic units. The near EW-oriented faults were predominantly active prior to the Permian era, coinciding with the Hercynian phase, whereas the NE-oriented faults were shaped later, during the transition from the Late Hercynian to the Indosinian period. The evolution of these strike-slip faults is intricately tied to a series of overlapping tectonic events. The culmination of the ancient uplift in central Sichuan predating the Permian era precipitated the genesis of the near EW-oriented faults. Subsequently, a pivotal tectonic regime shift during the Late Hercynian epoch, coupled with the subsequent Indosinian period’s fore-arc structural modifications near the Longmen Mountains, catalyzed the emergence of the NE-oriented faults. Moreover, the Deyang Anyue fault trough is identified as a pivotal factor in dictating the regional stress distribution, effectively hindering the east-west faults from traversing beyond the fault trough boundary, thereby stifling their further development.

CO₂ flooding is an important part of the CO₂ geological utilization process in CCUS(carbon capture, utilization and storage). The CO₂ flooding and storage project carried out in the Yanchang Oilfield has achieved good results in increasing production and storing CO₂. But the reasons of pipe string corrosion failure are still unclear during CO₂ injection. SEM(scanning electron microscopy), 3D confocal microscopy, EDS(energy dispersive spectrometer) and XRD(X-ray diffraction spectroscopy) were used to characterize the corrosion morphology of the gas injection pipe string in the CO₂ flooding and storage demonstration area of Wuqi Oilfield. The pipe string corrosion products are analyzed to clarify the reasons for pipe string failure caused by CO₂ corrosion. The results show that local corrosion dominated by CO₂ corrosion causes corrosion failure of the pipe string. Corrosion products include FeCO₃, high-priced oxides of Fe and a small amount of FeS. Continuous injection of low-temperature CO₂ cannot cause corrosion. However, the increase in wellbore temperature and the return of formation water caused by stopping CO₂ injection can create conditions for CO₂/H₂S corrosion in the pipe string. In addition, pipe string corrosion is accelerated when gas injection wells are converted into water injection wells. It is recommended to strengthen the sterilization and anti-corrosion measures for the pipe string during the period of stopping CO₂ injection and switching to water injection.

In order to study the failure mode and energy dissipation law of granite with double elliptical defects, dynamic splitting tensile experiments were conducted on granite with double elliptical defect angles of 0°, 45°, 90°, and 135° using a SHPB(split Hopkinson bar) device. The relationship between the angle and spacing of double elliptical defects, as well as the failure morphology and energy of granite, was explored. The results show that when the distance between double elliptical defects remains constant, the larger the included angle, the easier the specimen is to fracture. When the angle remains constant, the spacing increases and the rock sample is more prone to fracture. The dissipated energy density of the specimen decreases with the increase of the included angle, and the downward trend gradually tends to be gentle. The failure mode of the specimen is highly sensitive to the angle, that is, as the angle increases, the degree of fragmentation of the rock sample gradually intensifies, the symmetry of the fragments disappears, the wedge effect gradually becomes obvious, and the plasticity increases. When the included angle exceeds 90°, the degree of fragmentation begins to decrease again, and the rock sample exhibits symmetrical fracture.

There are various evaluation methods for the effectiveness of asphalt pavement grouting repair, most of which rely on on-site testing of a single indicator. Up to now, there are few related reports in the comprehensive evaluation of multiple indicators. In order to comprehensively understand the detection methods of asphalt pavement grouting repair effect and promote the development and application from single index evaluation to multi index evaluation methods, the research status of relative methods were summarized including drilling core method, grouting plug gauge method, deflection detection method, modulus inverse algorithm, ground penetrating radar method, and transient Rayleigh surface wave method in the detection of grouting filling quality, pavement strength, pavement modulus, compaction degree, void ratio, and grouting repair degree and other indicators. Furthermore, drawing on the current research status in the fields of tunnel grouting and goaf grouting, the application prospects of fuzzy analytic hierarchy process, grey correlation degree method were analyzed, as well as subjective and objective weighting cloud model in the evaluation of grouting repair effect of internal diseases in asphalt pavement, and looks forward to the development trend of precision, objectivity, and informatization in the evaluation of grouting repair effect of asphalt pavement were forecasted. Diversified method guidance is provided for evaluating the grouting repair effect of internal diseases in asphalt pavement.

Guangxi is located in the South China block, its structure is relatively stable, the seismic activity observed by the instrument is relatively weak. The little observation data leads to weak research on the crustal stress field in the area. In 2019, the Beiliu earthquake sequence occurrence in this area leads to the accumulation of considerable focal mechanism data. The focal mechanism data were collected in Guangxi and its adjacent areas. Using the grid search algorithm, the stress field in overall region and subregions were inverted. The results show as follows. The statistics of the focal mechanism in this area is mainly strike-slip type, and from the distribution of NW to ES, the focal mechanism of the reverse type gradually increases, and the focal mechanism of the normal fault type gradually decreases. The principal compressive stress axis of the overall stress field is NW-SE direction, the principal extensional stress axis is NE-SW direction, both of them are close to horizontal, which representing strike-slip type. The direction of the principal compressive stress axis in the western region is close to the N-E direction, and that in the east gradually changes to the direction of NW-SE, which makes the pattern of the compressive stress direction present a fan-shaped in the overall area. Based on the stress field analysis of subregions: NE-SW and NW-SE faults are easily generated in region-a by primarily of strike-slip type. NNE-SSW and NWW-SEE faults are easily generated in region-b, with NNE-SSW faults more towards reverse strike-slip type and NWW-SEE faults tending towards strike-slip type. Pure azimuth N-S and E-W faults are easily generated in region-c, but its main fault properties are not reflected due to the influence of surrounding fault extensions, with faults mainly of reverse strike-slip and reverse fault types. NW-SE and NE-SW faults are easily generated in region-d, with NW-SE faults more towards reverse fault and NE-SW faults tending towards strike-slip.

The sedimentary process and evolutionary model of crevasse fans are of great significance for predicting fluvial reservoirs and remaining oil potential. Taking the Dongyingzi fan in Liangcheng County as an example, based on satellite imaging and field geology, sedimentary features of Dongyingzi fan was analyzed. Using the SFM, the simulation gridding system, simulation parameters, and boundary conditions were designed to establish a numerical model of the crevasse fan. The plane distribution of sedimentary thickness, flow velocity and sand content at different numerical simulation stages were analyzed, as well as vertical sedimentary structure of the crevasse fan. The sedimentary model of crevasse fans was summarized to discuss its significance for Reservoir architecture. Research suggests that the crevasse fans consists of crevasse channels, composite proximal fans, and an distal fans. From a humid to an arid climate, the formation process of crevasse fans can be divided into four stages, which are river crevasse stage, proximal-fan forming stage, proximal-fan flourishing stage and diatal fan forming stage. As the flooding hydrodynamics decreases, crevasse channels, composite proximal fans and diatal fans are formed in sequence. The composite proximal and distal fans are sand-rich area, which are favorable types of sand bodies during the exploration. Crevasse channels are mud-rich area as the main type of interlayer. Composite proximal fans around the crevasse channels is the main site for residual oil enrichment in the later stage of hydrocarbon development.

Addressing the issues of large model parameters and high computational complexity in apple target detection algorithms for complex orchard environments, which hinder application on devices with limited computational resources, an improved and lightweight apple target detection algorithm named YOLOv8n-Apple based on YOLOv8 was proposed. The backbone network, yaniaNet, was introduced to reduce model parameters and complexity. The original C2f module in the model was replaced with the C2fGhost module, which further decreased model parameters by obtaining similar feature maps through fewer convolutional operations. The lightweight upsampling operator CARAFE was utilized to address the issues of semantic loss and excessively small receptive fields associated with traditional upsampling operators. Given that traditional loss functions cannot fully capture the relative position and size differences between targets, the WIoU bounding box was adopted as the regression loss function. A dataset comprising 3 120 images of mature apples in various scenarios, including distant and close views under front-light and backlight conditions, was collected from diverse angles and backgrounds, to mitigate potential dataset uncertainties. The improved apple detection model for orchard environments demonstrated an average detection accuracy of 90%, which was 7.5, 4.8, 2.2, 3.8, and 3.4 percentage points higher than SSD, Faster R-CNN, YOLOv5, YOLOv7, and YOLOv8, respectively. The detection speed reached 286 frames per second, and the model size was reduced to 1.8 MB, representing an improvement of 41 frames per second compared to the original model, while occupying only 60.0% of size.

As a major risk source, slope in open-pit coal mine is one of the main challenges faced by mine safety production. Taking Wanyuan open-pit coal mine in Wuhai City, Inner Mongolia Autonomous Region as an example, based on detailed investigation of slope development characteristics, deformation and failure modes were analyzed, slope radar deformation monitoring was carried out, and early warning models were established, a monitoring and early warning platform was built to achieve risk control. The results show that the slope of Wanyuan open-pit coal mine involves reverse, cross and consequent rock slope and soil slope of dump, and its deformation and failure modes are respectively tensile fracturing, wedge failure, slip-bending and creep (-tensile cracking). There is a possibility of instability under the influence of mining, blasting, rainfall or unreasonable stacking. On this basis, in order to realize the monitoring of slope without blind area, two sets of slope radar were respectively installed at the stable bedrock on the northeast and southwest sides of the mine, and the slope safety grade was divided into four grades: blue (<3 mm/h), yellow (3~8 mm/h), orange (8~15 mm/h) and red (>15 mm/h). Combined with the organizational structure of mining enterprises, the slope safety management system from slope radar deformation monitoring data-early warning model-early warning platform-risk management and control are constructed, which can provide technical reference for the construction of regional coal mine safety production capacity.