In order to improve the coupling effect of grain refinement and metamorphic refinement of A356 aluminum alloy. The mechanism of the composite treatment of adding AlTiB and Ce on the organization regulation law of α-Al grains and eutectic Si phase and the enhancement of mechanical properties were systematically investigated by using XRD, OM and TEM and mechanical property tests after heat treatment. The results showed that the coupling mechanism of AlTiB and Ce can significantly refine the α-Al grains and improve the morphology of eutectic Si. With the addition of 0.9% AlTiB and 0.3% Ce, α-Al secondary dendrite spacing refine from 23.71 μm to 17.44 μm, the average length of eutectic Si is shortened from 22.3 μm to 7.4 μm, and its morphology is transformed from a coarse needle-like shape to a rounded rod. The in-situ precipitated Ti₂Al₂₀Ce exists in the matrix in a diffusely distributed morphology, and combines well with the interface of the Si rich phase to form highly efficient heterogeneous nucleation sites; The tensile strength, elongation and Brinell hardness of the alloy in this composition reach288.5 MPa, 189 MPa, 4.9% and 59.5 HB, respectively, which are 61.5%, 23.8%, 53.1% and 29.4%higher compared with the pristine state of the aluminum alloy, respectively.

In order to study the effect of Ti content on the microstructure of hot-dip 55wt.% Al-Zn coating, hot-dip plating experiments were carried out on the aluminum-zinc substrate by configuring hot-dip galvanized aluminum liquid with different Ti contents. The surface, cross-section, and transition layer structure of aluminum-zinc coating with different Ti contents were analyzed by Optical Microscope(OM), Scanning Electron Microscope (SEM), and Energy Dispersive Spectrometer (EDS). The results showed that the microstructure of spangle on the surface of different Ti contents is basically the same, and the zinc spark and alloy layer on the surface of the coating are composed of Al-rich phase, Zn-rich phase, Si-rich phase, and Al-Zn-Fe-Si compound phase. When the Ti content is less than 0.035%, the size of the coating decreases significantly with the increase of Ti content, and the structure of the Ti-containing coating is relatively fine and dense. The addition of Ti increases the nucleation point during the solidification process of the plating solution, which is helpful to reduce the size of the spangle and refine the grain size of the coating alloy.

The total amount of straw resources is large with great potential for utilization. Straw, fertilizer and water retention gel were composited of straw/water retention gel slow-release brick fertilizer, whichcan be used to expand the application for straw fertilize. A water retention gel was prepared from low-cost potato starch, mixed with agricultural waste wheat straw powder after gel fertilization, and pectin was added as a binder to obtain a straw/water retention gel slow-release brick fertilizer by pressing. The water retention and water holding properties of the fertilizer bricks were investigated, and the potential of brick fertilizer in vegetable cultivation was studied through potting experiments. The study showed that the maximum water holding capacity of the soil can reach 72.45% with the addition of 4.00 g of slow-release brick fertilizer, and the equilibrium water retention can reach 10.72%. The nutrient release cycle of slow-release brick fertilizer reaches 24 days, and the nutrients remain unreleased on the 24th day is 13.89%. Cilantro treated with the slow-release fertilizer bricks exhibits the best growth with 1,2 more leaves, the plant height is 3.0~6.0 cm, and the root length 1.0~2.0 cm compared to those not treated with chemical fertilizers or treated with urea.

To study the effects of SiO₂ and PVA fibers on the static and dynamic mechanical properties of cement-based materials, the compressive strength, flexural, and impact resistance tests of Nano-SiO₂ mortar, PVA fiber mortar, and Nano-SiO₂-PVA fiber mortar were carried out. The impact number and impact energy of Nano-SiO₂-PVA fiber mortar were analyzed based on a two-parameter Weibull distribution. The results showed that the volume content of PVA fiber is 1.0 vol. % and the Nano-SiO₂ is 1.8%, the compressive strength and flexural strength of Nano-SiO₂-PVA fiber mortar are increased by 8.4% and 32%, respectively. Compared with ordinary mortar, the energy consumption of initial cracking and damage impact of Nano-SiO₂-PVA fiber mortar is increased by 833.3% and 1 160.0%, respectively. Although the addition of PVA fibers reduce the compressive strength of mortar, it significantly increases the energy consumption of initial cracking and damage impact.Nano-SiO₂ and PVA fiber exert a synergistic effect that improve the compactness of the matrix. Due to the bridging effect of PVA fiber and the filling effect of Nano-SiO₂, the matrix pores formed by PVA fibers are filled by the hydration products, refining pore morphology and delaying crack propagation. Furthermore, the impact times and impact energy consumption prediction models of Nano-SiO₂-PVA fiber mortar with different failure probabilities are established.

Taking a large-scale treatment and recycling system of vegetable wasteas an object, the operation data of the system during the six-month trial operation period were analyzed. The results showed that the system had the problems of intensive energy consumption in operation, insufficient waste heat recovery, and incomplete recycling of vegetable waste resources. In response, an optimized operational strategy for the operation and regulation mode of equipment on the energy supply side of the system is proposed. A cogeneration system with a biogas internal combustion engine as the power equipment to optimize the waste heat recovery process is used, and TRNSYS is used to simulate and verify the optimization system. The results show that the optimized system achieves an energy utilization efficiency of 83.76%, a cogeneration efficiency of 53.32%, and a 44.61% reduction in operating costs, thereby significantly enhancing both thermodynamic performance and economic viability.

The tooth contact pattern is a very important indicator for checking the meshing performance of gears. In the actual installation of spiral bevel gears, the unreasonable axial mounting distance of the large and small wheels often affects the correct meshing of the gears, leading to tooth surface damage and reduced transmission efficiency. Therefore reasonable adjustment of the gear axial misalignment is necessary. In this paper, under the conditions of considering the axial misalignment of the large wheel, the axial misalignment of the small wheel and the simultaneous existence of both, the finite element analysis method is adopted to simulate the meshing process of the spiral bevel gears at different mounting positions by adjusting the axial misalignment of the spiral bevel gears, so as to obtain the instantaneous contact patterns on the tooth surface of the large wheel for the three meshing states (meshing in, meshing in, and meshing out). The accuracy of the obtained contact patterns was verified using a rolling inspection machine. Then, the influence of the axial misalignment of the spiral bevel gears on the variation of tooth contact impressions was summarized, providing theoretical guidance for the actual installation and adjustment of the gears.

A lightweight design method is proposed for non-circular gears with eccentric characteristics leading to dynamic imbalance problems in the transmission process. Based on the elucidation of gear meshing principle, the data acquisition and modeling of non-circular gear tooth surface is realized. A multi-objective topology optimization method is adopted to optimize the spokes of non-circular gears by considering the effects of static stresses and dynamic responses of different gear tooth positions by combining the compromise planning method and the gray correlation method. The spokes are then optimized in the tooth width direction to realize the lightweight design of non-circular gears. The transmission characteristics before and after the optimized design are compared by solid data measurement and dynamics simulation analysis. The results show that the overall weight of the non-circular gear is reduced by 38.87%, and the modal order of its circumferential vibration is increased from 2nd to 3rd order. indicating improved dynamic balance. The optimized gear exhibits smoother transmission, more accurate transmission ratios, reduced tooth surface, and enhanced fatigue life. These results provide a theoretical basis for the lightweight design and transmission characteristics optimization of the non-circular gear.

Aiming at the problem of difficulty in identifying the fault category caused by the nonlinear and non-smooth characteristics of rolling bearing fault signal, a fault identification method based on the combination of Local Mean Decomposition (LMD), multi-scale sample entropy and GG clustering algorithm is proposed. Initially, the fault signals of rolling bearings are decomposed using LMD to obtain multiple product function (PF) components, enabling the preliminary extraction of rolling bearing state features. Then, the optimal PF components are selected by correlation analysis, and the sample entropy value are computed at multiple scales. Finally, the principal component analysis is employed to visualize and reduce the dimensionality of the high-dimensional feature vectors. The new feature vectors are visualized by principal component analysis, which are then input into the GG clustering algorithm to realize the identification of rolling bearing fault categories. The results show that the proposed method has the advantage of better clustering effect compared with other pattern combination methods.

The traditional Bootstrap method, when applied to small-sample fatigue test data, is limited by the fact that it can only resample from the original data, thereby constraining the amount of available information. To overcome this limitation, it is proposed to introduce grey system theory to process small-sample data by establishing grey differential equations that uncover hidden relationships within the original data, thus extracting additional implicit information. First, the original data are processed using grey system theory. Secondly, the bootstrap method is used to sample the processed data to obtain regenerated samples. Finally, the P-S-N curve of the small sample data was obtained by reprocessing the regenerated data. Through validation analysis, compared with the Bootstrap method, the grey Bootstrap method proposed in this paper has higher accuracy in processing the small sample P-S-N curve.

In order to improve the fatigue performance and extend the fatigue life of the aluminum plate-fin heat exchanger used in liquefied natural gas (LNG) applications, based on fatigue testing and fracture morphology analysis methods, the fatigue fracture morphology characteristics of the typical areas of the main material Al3003 are compared and analyzed through macroscopic and scanning electron microscopy observations, and the fatigue mechanism of Al3003 is explored. The results indicate that the average fatigue lives of Al3003 under high and low cyclic stresses are 1.92×10⁴ cycles and 4.79×10⁶ cycles, respectively. The fatigue zone of Al3003 exhibits a similar crack propagation process under high and low cyclic stresses, but its area and number of internal fatigue sources are different. There is only one fatigue source inside the specimen under high cyclic stress, whereas there are two main fatigue sources and numerous small fatigue sources inside the specimen under low cyclic stress. The critical zone of Al3003 under high and low cyclic stress has similar overall morphology characteristics, but its slip bands and tearing morphology are different in density. The instantaneous fracture zone of Al3003 under high and low cyclic stress has similar morphological characteristics; however, the proportion of its extension morphology in the instantaneous fracture zone is different.

Aiming at the problems of the controller performance degradation and the lack of accurate and efficient maintenance due to long-term and efficient operation for process industrial control systems with numerous loops, a controller performance assessment method of complex ratio control system is proposed for the benzene-ethylene ratio control system of the hydrocarbonization unit in a styrene plant. Firstly, a control structure of the benzene-ethylene ratio system with 1 main-4 pairs is constructed by analyzing the process mechanism. Secondly, the dynamic performance assessment for controllers of five single-loop systems is implemented based on the improved generalized minimum entropy benchmark using the sliding data window method. Then the following performance index is designed to assess the cooperative control performance between each loop of the system. After that, the combined performance index of the system is formulated. The weights of the combined performance index are determined by the Spearman correlation coefficient method, and the overall assessment of the controller performance for the benzene-ethylene ratio control system is realized. Finally, experimental studies demonstrate the effectiveness and feasibility of the proposed controller performance evaluation method, which can promptly detect suboptimal system states.

The security control problem is investigated for the nonlinear information physical system with mixed time-delays under an all-around attack environment. Firstly, a time-delay system model with multiple constraint parameters is established by considering the effect of cyber-attacks, physical attacks, and mixed time-delays. Secondly, sufficient conditions are derived for the closed-loop system to be mean-square stable by utilizing the Lyapunov theory and linear matrix inequality technology. Based on these results, a secure controller ensuring the mean-square stability of the system is designed. Finally, the correctness and effectiveness of the proposed control method are verified by a simulation example.

To address the challenges posed by large-scale small object detection, dense object distribution, and issues of missed detections and false positives in remote sensing images, this paper introduces a remote sensing image object detection approach grounded in an enhanced YOLOv7 model. Initially, the method integrates the DCNv2 structure and residual architecture into the YOLOv7 model, reconstructing a novel backbone network to enhance the extraction of shallow-level features information and improve network accuracy. Subsequently, a pioneering feature fusion module is incorporated into the neck network, combined with the SimAM mechanism, which adaptively adjusts the fusion weights of both shallow-level texture information and deep-level semantic information, thereby effectively curbing noise introduced during shallow feature extraction and augmenting the representation of essential features. Finally, the normalized Gaussian Wasserstein distance loss function is used as the regression loss function, replacing the traditional IOU to improve the detection capability for multi-scale targets. Empirical findings derived from the DOTAv1.0 dataset reveal an average precision of 20.1% for small objects, while the DIOR dataset yields an average precision of 29.0%. Furthermore, compared to recent advanced methods such as YOLOv7 and YOLOv6, the proposed algorithm demonstrates strong competitive performance.

Aiming at the problem that the solar-blind ultraviolet image and visible light image based on single photon counting have few similar features, image superposition and image filtering are used to preprocess the solar-blind ultraviolet image. Then the centroid extraction and Hough transform are used to obtain the coordinates of calibration points in both the solar-blind ultraviolet image and the visible light image. The Zhang’s camera calibration method was then employed to calibrate the solar-blind ultraviolet camera and the visible light camera. Finally, a registration method based on the binocular vision imaging principle was utilized to derive the coordinate mapping relationship between the solar-blind ultraviolet image and the visible light image. An image fusion process was performed using a weighted averaging fusion algorithm. A series of imaging and data processing experiments were carried out on the ultraviolet light source, and the experimental results verified the feasibility of the calibration fusion algorithm designed for the solar-blind ultraviolet-visible dual-spectrum imaging detection.

Scaling off disease commonly develops in the rammed-earth Great Wall in Northwest China. In order to delay the deterioration process of the Great Wall, more effective reinforcement methods were explored through experiments. First, based on the measured thickness of peeling layers, a liquid-supply duration test was conducted to determine the optimal slurry supply time, which was identified as 18 h for achieving the intended penetration depth. Subsequently, liquid-supply optimization tests were performed, and the most favorable supply mode was selected according to the position of the slurry, the infiltration amount of the slurry, and the water distribution in the wall. To evaluate the reinforcement effect when the penetration purpose was achieved, samples from different radii of the wall in the reinforcement area were tested through wave-velocity test, hardness test, wind erosion test, and disintegration test. In addition, scanning electron microscopy was employed to compare the microstructures of untreated and electro-osmotic-reinforced specimens, aiming to elucidate the underlying strengthening mechanism. The results show that intermittent liquid supply can improve the uniformity of slurry distribution and reduce the difference of water distribution along the radial direction. What’s more, the reinforcement effect of slurry on-off ratio of t∶1 is better than t∶2. Microstructural analysis further reveals that the pores of the reinforced soil are obviously reduced significantly.

To clarify the improving effect of the steel ratio on mechanical performance and applicability of Code formulas of recycled aggregate concrete-filled square steel tube (RACFST) short column with 100% recycled coarse aggregate replacement ratio, experimental studies were performed. A total of 10 specimens, including both square CFST and RACFST columns, were designed and tested. Based on the experimental results, the influencing mechanism of steel ratio on failure mode, load-displacement behaviour, fracture toughness, ductility and load-carrying capacity was analyzed, and the strength predicting method was discussed. Results show that the increase of steel ratio can effectively improve the mechanical performances of square RACFST, but the improvement is not proportional to the steel ratio. With the lower steel ratio, the prediction results of the code are higher than experimental values and reliability reduces, and the reliability of prediction results, however, tends to stabilise with the increase of steel ratio. When the steel ratio is greater than 9%, the load-carrying capacity evaluation formulas given by the code can be used to predict the axial strength of square RACFST short columns with 100% recycled coarse aggregate replacement ratio.

The seismic optimization design of a multi-level loess slope under earthquake is mainly studied here. Considering practical engineering constraints of limited sloping space, multi-level loess slope with constant overall slope ratios is selected as the research object. Numerical simulations of different multi-level slope configurations are conducted using Geo-Studio finite element software. By varying the width of platform and the grade of slope, the dynamic response and stability of slope under earthquake are studied The results show that under the premise of constant comprehensive slope rate, the slope angle of each grade gradually increases with the increase of platform width. Correspondingly, the acceleration and displacement response of the slope under earthquake becomes more enhanced, and its dynamic stability first increase and then decrease. In addition, the slope angle of each grade of slope increases as the grade number of slope levels increases. The acceleration and displacement responses of the slope under seismic action show the characteristics of first increasing and then decreasing, and its seismic stability follows the same trend of first increasing and then decreasing.

The dynamic response and response ratio of the structure system are deduced by establishing the motion equation of the impact zone of the spherical reticulated shell under the triangular pulse load. At the same time, based on the principle of approximate energy, the large plastic deformation of spherical reticulated shell structure under impact loading is calculated, and the radius of the shell concave area under single point impact at the top of the structure is simplified. The K6 single-layer spherical reticulated shell is established in ANSYS/LS-DYNA to numerically validate the derived expression. The results show that the main influencing factors of the maximum response of the structure are the duration of the impact load and the natural frequency of the structural system. The concave radius is affected by the curvature radius, equivalent thickness, edge width, yield stress, and impact energy absorbed by the structure. Moreover, the theoretical value is close to the simulation value.

In order to explore a new tilting correcting method of shallow foundation buildingin loess areas, a 2-story office building with uneven settlement in Lanzhou City was taken as the research object. After analyzing the causes of settlement, a new type of correction structure was proposed, consisting of inverted L-shaped beams added on both sides of the brick foundation and independent foundation diagonal lifting under the column, combined with a limit iteration lifting method. After verifying the bending, shear, and impact shear bearing capacities, the proposed scheme was implemented. Monitoring results show that the relative settlement at Q₁, Q₂, and Z₁ on the southwest side of the original building is relatively large, with a cumulative settlement of over 40mm and a local tilt rate of 0.7% at Q₁ and Z₁. After correction, the lifting amount of Q₁ and Z₁ are both 29 mm, reducing the tilt ratio to 0.17%, which meets the safety requirements of the specifications. The construction process was characterized by a short duration, simple procedures, and stable execution.

In order to thoroughly study the influence of the ultra-deep foundation pit excavation on the surrounding environment, the settlement of the surrounding buildings, pipeline settlement, road settlement and deformation of the different retaining structures caused by the excavation of deep foundation pit of a metro station were systematically monitored. The variation law of monitoring results was analyzed, and the numerical simulation was carried out with a finite element software to compare and verify the deformation influence of the foundation pit excavation on the different retaining structures and surrounding environment. The results show that the maximum settlement around the foundation pit is about 0.08%H (H is the excavation depth of the foundation pit), and the maximum horizontal displacement of the piles is about 0.07%H. When the upper part of the strata is the soil and the lower part is the rock with good mechanical properties within the excavation depth of a deep foundation pit, using the h-type piles support structure can reduce the horizontal displacement of the deep soil by about 40% compared with normal piles. Because the front row of the h-type piles is embedded in the rock with good mechanical properties, the horizontal displacement of the pile is small and the structure is stable during excavation. Using the h-type piles as the retaining structure can reduce the construction difficulty and shorten the construction period. Therefore, it is advantageous to use the h-type piles for the retaining structure in similar strata.

To study the gradient estimations of solutions for a class of elliptic harmonic equations in Besov space, appropriate structural conditions for operator A and operator B were established first. Then, a vector field function was introduced, in conjunction with the structural conditions of operator A, to derive a quasi-monotonicity inequality. The growth of the gradient was estimated by employing finite difference methods, Hölder’s inequality, and Young’s inequality. Finally, the regularity results for the gradient of the solutions in the Besov space were obtainedby utilizing embedding theorems.

The nonlinear dynamic response of graphene platelets reinforced functionally graded (FG-GPLRC) beams under electric field is studied. Considering the dielectric effect, the content of graphene platelets (GPL) varies gradiently along the thickness direction of the beam in three distribution modes, and the equivalent elastic modulus and equivalent dielectric constant are calculated by the effective medium theory. Based on the von Kármán nonlinear strain-displacement relationship, the nonlinear dynamic governing equations are derived by Lagrange equation. The displacement approximation function is introduced to convert the equations into nonlinear ordinary differential equations by the Rayleigh-Ritz method, and the dynamic response is obtained by numerical solution of the Runge-Kutta method. The relationships between the nonlinear dynamic response of the FG-GPLRC beam under variable electric field and GPL volume fraction, distribution mode, GPL geometric size, pre-applied tensile stress, DC voltage, and AC frequency are discussed. Quantitative analysis shows that the dynamic response of FG-GPLRC beams can be designed by adjusting multiple parameters.