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.

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.

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.

With the gradual formation of “trunk-branch” linkage multi-level air cargo transportation system, the problem of low turnover efficiency of airport cargo is becoming more and more prominent, and the “trunk-branch” linkage efficient cargo allocation methods have become one of the key technologies to solve the above problems. An integer programming linkage allocation model was established with the maximum loading rate under “trunk-branch” linkage as the optimization objective while simultaneously satisfying constraints such as cabin position, cabin size, center of gravity, and weight for both trunk and branch aircraft. This model was applied based on genetic algorithms to optimize the cargo allocation between the B757-200 trunk aircraft and the ARJ21-700F branch aircraft. It was found that the average loading rate of “trunk-branch” linkage allocation was increased by 5.45% to 72.05% compared with sequential allocation.By demonstrating that the proposed “trunk-branch” linkage allocation method in this study can significantly increase the overall cargo loading capacity, and thus effectively improving the efficiency of cargo turnover at airports, laying a theoretical foundation and providing technical support for the safe and efficient development of the “trunk-branch” linkage multi-level air cargo transportation system.

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.

There are certain requirements for the mechanical properties of paper or paper-based materials during their service. However, existing experimental and theoretical studies of size effects indicate that the mechanical properties of specimens with different sizes are not identical. Therefore, it is necessary to clarify the size effect of their mechanical properties to ensure their safety. The kraft paper, which is easy to obtain and has high strength, was selected to carry out uniaxial tensile tests on with different sizes. And then the size effects of mechanical properties and their dispersions were determined. By analyzing the deformation characteristics and macro-microscopic damage features of different sizes specimens, the intrinsic mechanism of the size effect on the mechanical properties of kraft paper was revealed. Finally, a size effect model of mechanical properties for kraft paper was established. The study finds that the nominal tensile strength and nominal peak strain of kraft paper first increase and then decrease as the sizes increases. This is because the cut edge fibers cause the edges of the kraft paper specimens to have weaker stress and strain capabilities, and the proportion of weakened edges in small-sized specimens is relatively large, leading to an increasing size effect on the nominal tensile strength and nominal peak strain. In large-sized specimens, the proportion of weakened edges can be ignored, and the internal fracture process zone plays a dominant role, leading to a decreasing size effect on the nominal tensile strength and nominal peak strain. The established edge-internal fracture process zone size effect model can well describe the size effect on the nominal tensile strength and nominal peak strain of kraft paper. However, this model cannot capture the nonlinear characteristics of the increasing size effect stage for the nominal tensile strength and nominal peak strain.

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.

To address the issues of long stitching time due to numerous mismatched feature points and insufficient stitching accuracy when using all feature points directly in image stitching tasks, an optimized image stitching method combining a matching point increasing strategy with RANSAC(random sample consensus) was proposed. The method initially screened feature points to prevent numerous ineffective samples, thus improving computational efficiency. Then, a progressive sampling strategy was employed to incrementally increase matching points and repeatedly sample for precise results. Finally, the optimal model was obtained by utilizing a new loss function based on root mean square error to filter the results. The experimental results indicate that, without a noticeable increase in time consumption, the interior point rate of the algorithm in this paper is further enhanced, the mean and root mean square errors of feature points have decreased significantly, the accuracy of image stitching is improved, the misalignment phenomenon at the stitching seam is effectively improved, and the stitching errors in image stitching tasks are significantly reduced.

The changes in clouds are complex and diverse, playing a significant role in weather forecast and disaster warning, and affecting our daily lives. The observation of clouds is mainly carried out through radar, remote sensing satellites, and all-sky imagers. The recorded cloud images are divided into radar cloud images, satellite cloud images, and ground-based cloud images, all of which are indispensable parts of cloud observation. With the development of machine learning in multiple fields, it has gradually been applied to cloud segmentation and has made great progress. Through extensive research on literature and achievements in related fields, machine learning cloud segmentation was divided into three types: cloud segmentation methods based on neural networks, cloud segmentation methods based on transfer learning, and cloud segmentation methods based on lightweight models. The methods proposed in recent years for each type were compared, and improvement methods for different problems in cloud segmentation were further summarized. Several improvement schemes were provided for reference.

In order to study the influence of overlying load on the internal deformation of soil outside the foundation pit, a transparent soil test chamber with controllable deformation mode of retaining structure was designed and combined with particle image velocimetry technology to analyze the influence of different deformation modes of retaining structure and overlying load on the internal deformation of soil. The reliability of the test results was verified by comparing the data obtained from the transparent soil test with the prediction curve and the engineering example. The results show that the overlying load has a significant effect on the displacement field of the soil outside the pit. Increasing the overlying load or reducing the distance between the overlying load and the retaining structure will make the influence area of soil displacement outside the pit expand to the deep soil layer, and the maximum vertical settlement and horizontal displacement will also increase. The soil depth of the soil outside the cantilever type and the convex type is significantly affected by the overlying load pressure and distance. The displacement of the upper soil is significantly affected by changing the pressure and distance of the overlying load in the cantilever deformation mode, but the displacement of the middle and lower soil is more significantly affected by changing the pressure and distance of the overlying load in the convex deformation mode. Compared with reducing the distance of the overlying load in the same proportion, increasing the overlying load has a greater impact on the displacement. It can be seen that in the actual project, it is necessary to combine the local building distribution with the underground engineering environment, and take appropriate measures to avoid the most unfavorable deformation mode of the retaining structure.