Ni₃Al-based composite coatings containing different mass-fractions of Ag solid lubricant were prepared on the 310S austenitic stainless steel by laser cladding technology, and the effects of Agmass-fraction(5%, 10%, 15%) on the phase composition, microhardness, tribological properties and worn surface phase composition of the coatings were investigated. The results showed that the microhardness of the composite coatings decrease with the increasing of Ag content due to its soft nature, and the coating still has relatively high microhardness when the Ag content reach 10%, which is about 198.37 HV. The introduction of 10% Ag into the Ni₃Al coatingreduce the friction coefficients of the coating from 0.69~0.55 to0.62~0.41 at 25~800 ℃, and the wear ratesof the coating decrease from (2.27~1.60)×10^－5 mm³/(N·m)to (1.28~0.44)×10^－5 mm³/(N·m)at 400~800 ℃. The enhancement of the anti-friction ability of the composite coating is related to the synergistic lubrication of the diffusive migration of soft metal Ag within 25~400 ℃ and the oxidation products of Ni₃Al and Ag within 400~800 ℃; while the improvement of the wear resistance of the coating is associated with its higher mechanical strength and the formation of a continuous protective film on the worn surface.

During the electrolytic refining of copper, the stainless steel substrate is used as a permanent cathode, and the flatness of the substrate has an important influence on the efficiency and energy consumption of electrolytic copper. In the large-scale production of electrolytic copper stainless steel cathode plates, the influence of the cathode plate leveling method on the elastic modulus of the substrate was studied. The elastic modulus of the 316L stainless steel substrate was measured using the deflection method, and the influence of different leveling times and directions on the elastic modulus of the 316L stainless steel substrate was explored. The results showed that when leveling in one direction, the elastic modulus of the stainless steel substrate gradually decreases with the increase of the leveling times. When leveling in the longitudinal and transverse directions, the elastic modulus also shows a downward trend, with a more pronounced reduction observed in the longitudinal direction.

Photothermal catalysis technology can reduce CO₂ into chemical fuels and industrial raw materials, providing a novel green and efficient way to deal with the challenges of global warming and energy crisis. Oxygen-rich vacancy TiO₂ (TiO_2－x) photothermal catalysts was prepared by the sol-gel method combined with heat treatment in one step.The microstructure, crystal structure and optical properties were characterized by XRD, XPS, TEM and EPR.The effects of reaction conditions such as the amount of photothermal catalyst, total gas flow rate, optical density, CO₂/H₂ ratio and temperature on the photothermal reduction of CO₂ by TiO_2－x were studied, the parameters were optimized, and the photothermal catalytic mechanism of TiO_2－x was explored too.The results showed that the main product of TiO_2－x photothermal catalytic CO₂ reduction is CO.The CO yields of TiO_2－x is 2.23 mmol·g^－1·h^－1, which is 2.4 times that of commercial TiO₂ (P25).The CO yield of TiO_2－x photothermal catalysis is 59.3 times that of photocatalytic CO yield alone and 1.77 times that of thermal catalysis alone.The efficiency of photothermal synergistic catalysis is greatly improved compared to photocatalytic or thermal catalysis alone.

The durability of fiber reinforced concrete (FRC) was studied with 3.5%NaCl+5%Na₂SO₄ composite solution as the erosion medium. Six groups of FRC specimens were designed to study the influence of steel fiber (SF) and polypropylene fiber (PF) single or mixed on the performance of concrete against partial immersion erosion by composite salt, using appearance morphology, erosion height, mass loss rate, relative dynamic modulus of elasticity and relative compressive strength as test indexes. The results showed that single doping PF or hybrid SF-PF decrease the rise height of the solution, while the addition of 1% SF increase the salt crystallization on the surface of the specimen and solution rise height. The mass loss rate of FRC decrease first and then increase with the increase of erosion age, while the relative dynamic modulus of elasticity and relative compressive strength show the opposite pattern. The compressive strength of the specimens with 1% SF decrease the least. According to the results of thermogravimetric analysis, the corrosion products generated in the concrete in the gas-liquid zone above the liquid level are mainly AFt and Friedel’s, and the addition of SF and PF have an inhibitory effect on the reduction of Ca(OH)₂.

It is an inevitable phenomenon that the skidding of deep groove ball bearings during operation, which will accelerate bearing wear, reduce rotation accuracy, and cause severe vibration and noise. In order to reveal the skidding mechanism of bearings, the parameters of cage pocket clearance are introduced. The interaction between rolling elements and cage units, rolling elements and raceways, and cage units are analyzed. The skidding dynamic model of deep groove ball bearing is developed. Based on the fourth-order Runge-Kutta method, the dynamic differential equations are solved, the simulation signals of the model are obtained, and the simulation results of the model are analyzed. The effects of different rotational speeds, radial loads, equivalent stiffness between flexible cage units, and cage pocket clearance on the sliding speed between inner ring and rolling elements and cage slip ratio are studied. The results show that high speed and low load will aggravate the skidding of the bearing. Increasing the equivalent stiffness between flexible cage units or reducing the cage pocket clearance can reduce the skidding of the bearing. However, neglecting the cage pocket clearance leads to more severe skid behavior. The study provides a theoretical basis for the structural design and failure analysis of deep groove ball bearings.

Aiming at the problem that the traditional rolling bearing fault diagnosis method has insufficient feature extraction and poor diagnosis rate under variable noise, working conditions, and load conditions, a rolling bearing fault diagnosis method of multichannel convolutional neural network (MCNN) is proposed. Firstly, a multi-channel dense connection module is designed, which strengthens the information connection between different convolutional layers through dense connection and effectively extracts fault information. Then, a hollow convolution module with adaptively parametric rectifier linear unit (APReLU) is designed, which assigns different weighting coefficients to each channel to extract more important and critical information. Finally, the Inception module is used to reduce the feature dimensionality and further extract the fault features. Fault diagnosis of rolling bearings is realized by means of multiple classification functions. The method was validated using the bearing dataset of Case Western Reserve University and the gearbox dataset of Southeast University. The experimental results of the bearing data set show that under variable noise conditions, the proposed method achieved an average accuracy of 98.50%. Under varying load conditions, the accuracy ranged from 91.7% to 97.7%, and under varying operating conditions, from 87.79% to 96.71%. In the gearbox data set, the fault diagnosis accuracy is as high as 99.84%. Compared with rolling bearing fault diagnosis other methods, the proposed method has a higher fault diagnosis rate and better generalization performance across different data sets and variable noise, load and working conditions.

The machining accuracy of computer numerically controlled (CNC) machine tools is an important factor affecting product quality. To improve the machining accuracy reliability of multi-axis CNC machine tools, based on the product-of-exponential (POE) theory, the geometric error model and machining accuracy reliability model of machine tools are established. Using the improved first-order second-moment method, the machining accuracy reliability of machine tools is analyzed, as well as the sensitivity of geometric error terms. A universal accuracy allocation method to optimize the machining accuracy of machine tools is proposed, which not only gives the physical meaning of machine tools’ perpendicularity error but also solves the problem of matrix singularity. Taking a large guideway gantry grinder as an example, according to the sensitivity analysis results of geometric error terms, the machining accuracy reliability of the grinder was improved by optimizing and adjusting the parameters of main geometric error terms. The results show that the accuracy allocation method proposed in this paper is both effective and practical.

In order to study the effect of vortex generators (VGs) and blade combinations on the aerodynamic performance of wind turbine blades, the NREL Phase VI wind turbine blades were taken as models. The CFD method was used to simulate eight flow control configurations, including single and double VGs, single and double blades, and their combinations. The impact of these configurations on the aerodynamic performance of wind turbine blades under different wind speeds was analyzed. The calculation results show that the combinations of single VGs with single blade, as well as double VGs with single blade not only obtain higher output torque but also more effectively inhibit the flow separation in the chord and span directions of the blade. These combinations combine the advantages of both devices, demonstrating better flow control effect. Furthermore, compared with single VGs, double VGs can further delay flow separation.

The buried polyethylene gas pipeline with scratches is prone to stress concentration under vehicle-mounted action, which speed up the damage of the pipeline, resulting in pipeline failure and ignition and explosion accidents. Based on the force transfer analysis, a nonlinear mechanical coupling model was established to explain the action path of vehicle-mounted, soil-scratched polyethylene pipe. The effects of load, internal pressure, buried depth, soil elastic modulus, and scratch depth on the pipe were analyzed. The results show that stress concentration occurs in the defect area of the scratched pipeline. The Mises stress is directly proportional to the changes of load, internal pressure, buried depth, and defect depth, and inversely proportional to the elastic modulus of soil under the condition of soil dead weight. When the Mises stress was 5.75 MPa or the internal pressure was 0.24 MPa, the maximum Mises stress reached the allowable stress. At an internal pressure of 0.52 MPa, the pipeline reached the yield strength and failed. When the scratch depth is shallow, the pipe failure starts from the middle part of the scratch front. When the ratio of the defect depth to the pipe wall thickness is a/t≥0.4, the stress concentration occurs at the end of the scratch, and the failure starts from both ends of the scratch.

Aiming at the problem of security risks caused by insufficient system life due to motor degradation in the 3D stage Wire system, a real-time system remaining useful life prediction method based on a multi-stage degradation model was proposed. Firstly, the multi-stage Wiener process is used to model the insulation aging of the servo motor, and the CUSUM is used to detect the change point to realize the stage division. Secondly, considering the influence of measurement noise, Kalman filtering, and RTS (Rauch-Tung-Striebel) smoothing algorithm are used to estimate the true degradation state, and the change point detection results are integrated into the parameter estimation process based on the expectation maximization algorithm to realize real-time online update and stage replacement of model parameters. Finally, using the real-time position error as the system performance evaluation index, the system-level online remaining useful life prediction of 3D stage Wire was realized. The simulation results show that the proposed method can not only accurately identify the change time of each stage of the degradation process, but also better align with the actual degradation process, which can effectively improve the prediction accuracy of the remaining life, so as to provide a reliable basis for the subsequent precise maintenance.

In multi-modal multi-objective optimization, the diversity in both the decision space and the objective space plays a critical role in the impact on the performance of the algorithm. To better balance the diversity between the two, proposes a multi-modal multi-objective optimization algorithm based on diversity index ranking (D-DNEAL) is proposed in this paper. First, D-DNEAL constructs a diversity indicator using the K-nearest neighbor density estimation method, which is then integrated into the fast non-dominated sorting process to rank individuals. This ensures that individuals with poor convergence but good distribution still have a chance to be selected for the next generation, thereby improving the search ability of the population. Additionally, multi-frontier archiving mechanism is introduced to preserve the individuals with better diversity, so that the algorithm can obtain more local optimal solutions. To verify the performance of D-DNEAL on multi-modal multi-objective optimization problems, six state-of-the-art algorithms are used to make a comparison on 28 multi-modal multi-objective optimization test problems. The results show that the D-DNEAL is effective in solving multi-modal multi-objective problems.

For the problem of melanoma image diagnosis, this paper proposes a recognition method based on a deformable partition attention mechanism. This method adopts a coarse-to-fine feature extraction and recognition strategy to accurately distinguish melanoma from common moles and establish corresponding semantic labels. Based on this, a multimodal dermatological corpus is constructed by integrating case texts. First, to tackle issues such as blurred lesion boundaries, uneven distribution, and difficulty in feature extraction, this paper introduces a deformable partition attention module that combines attention mechanisms with deformable convolutions. Second, to address the large differences between benign and malignant subcategories that result in training difficulties and low recognition efficiency, this paper constructs a hierarchical learning framework that progresses from coarse to fine categories. In addition, a joint loss function is introduced to optimize the model’s recognition accuracy. Experimental results show that the proposed algorithm demonstrates high sensitivity and specificity on self-constructed dataset, effectively improving the accuracy of multimodal dermatological corpus construction by matching case texts with medical images.

In order to solve the problem of low signal-to-noise ratio for radar echo signals in a sheltered environment and the masking of human heartbeat signal by respiratory harmonics and other clutter, a noise reduction method based on improved singular value decomposition (ISVD) and a vital signs extraction method based on improved time-varying filtering empirical mode decomposition (ITVFEMD) is proposed. First, the radar echo signals are preprocessed using the improved singular value decomposition algorithm. Subsequently, the preprocessed signals undergo parameter-optimized ITVFEMD to decompose the signal into intrinsic mode functions (IMFs). Appropriate IMFs are then selected to reconstruct the respiratory and heartbeat signals. The reconstructed signals are analyzed via Fast Fourier Transform (FFT) to estimate the corresponding respiratory and heartbeat frequencies. Finally, the estimated frequencies are compared with ground truth data obtained from a pulse oximeter for consistency analysis. Experimental results show that the proposed method achieves estimation accuracies of over 95% for heart rate and 98% for respiratory rate.

In order to explore the interface bonding performance of steel wire mesh reinforced ECC and concrete, the interfacial bonding performance of a total of 21 beam specimens designed and manufactured by 7 groups were tested with concrete strength, interface bonding length and bond width as test parameters. The results show that there are two failure modes: interface stripping and strand rupture. The interface peeling capacity increases with the increase of concrete strength. In the range of effective bonding length, the interface stripping capacity increases with the increase of bonding length, but has no obvious effect on the interface bonding strength. The bonding width of the interface has no significant effect on the tensile strength of the interface, but the bonding strength decreases. Based on the statistical analysis of effective bonding length test, the prediction model of the interface stripping capacity between steel wire mesh reinforced ECC and concrete was established, and the verification analysis showed that the prediction formula had good applicability.

In view of the complex seismic response of curved girder bridges caused by plane irregularity, this study investigates the effects of different isolation bearings on seismic response and energy dissipation. Finite element models with Linear Natural Rubber (LNR) bearings were established using ANSYS, and horizontal bi-directional ground motions selected from the code-based response spectrum were applied. Lead Rubber Bearings (LRB) and High Damping Rubber Bearings (HDR) were further analyzed to evaluate their seismic isolation performance. Results show that, compared with LNR bearings, LRB and HDR bearings significantly reduce radial and tangential displacements (by 66.7% and 67.4%, respectively) and exhibit larger cumulative energy dissipation (maximum ratios of 2.26 and 2.13). Both bearings demonstrate good isolation performance and can be selected according to engineering needs. However, under different ground motions, seismic responses and the onset of bearing energy dissipation vary, highlighting the necessity of considering ground motion characteristics in seismic design.

At present, domestic tank seismic codes and standards are mainly based on the assumption of rigid foundation, neglecting the effects of soil-structure interaction (SSI) and the cross-interaction between adjacent tanks. A coupled liquid-solid model of a storage tank was developed using the CEL method in ABAQUS. Seismic response analyses were performed under excitation from three recorded natural earthquake waves for systems involving both single tanks and multiple tanks (tank groups), incorporating SSI effects. Taking the tank in the center of the site as the research object, the seismic response of the tank in the case of a single tank soil system and a soil group tank system is compared. The research results show that under a given seismic input, the axial stress of the tank wall at 0.5m above the bottom of the tank exceeds the critical buckling stress, and the tank body has obvious elephant foot deformation. The existence of adjacent tanks around reduces the seismic response of the tank body to some extent. Through the analysis of the ground acceleration of the site, the results show that the presence of the tank body will increase the ground acceleration response.

Aiming at the problem of insufficient research on the deformation calculation of the secant pile at present, on the basis of considering the effect of the top beam, the p-y curve method is used to establish the deformation calculation model of the secant pile, and the formula for calculating the structural deformation of the secant pile is deduced. The finite difference method is used to solve the formula for calculating the deformation of secant pile structure. Based on the case of a deep foundation pit in Lanzhou, the results calculated by the proposed calculation method are compared with the results simulated by the PLAXIS 3D finite element software. The results show that:When calculating the deformation of secant pile, it is feasible to equivalent secant pile structure to underground diaphragm wall structure through stiffness equivalent principle.There is a cooperative deformation relationship between the top beam and the secant pile structure, and the top beam can control the deformation of the secant pile structure.Although the trend of the results calculated by the proposed calculation method is the same as that of the numerical simulation, there are some differences in the numerical value, which is due to the different constraint conditions of the bottom of the secant pile and the constitutive relation of the soil in the process of calculation and simulation.

In order to solve the problem that the equivalent stiffness of BRB is difficult to match the serial stiffness of its system, a calculation method of BRB yield force is proposed by introducing the ratio of member length to axis length (length ratio). Based on the deficiency of the simplified algorithm of equivalent bracing, the key factors affecting the stiffness matching are analyzed; According to the modified parallel force method, the relationship between the length ratio and the support angle, axis length, yield force and other parameters is analyzed, and then the calculation formula is fitted and the reference range in practical engineering is given; The method of BRB yield force based on length ratio is deduced, and the influence of different yield force values on stiffness error is analyzed. The results show that the modified parallel force method is simple and reasonable; The length ratio, yield force and system stiffness are interrelated. If the yield force is too small, the stiffness error increases with the reduction of the yield force. If the value is too large, the stiffness error increases with the increase of the yield force. The BRB yield force value taking method based on the length ratio can effectively match the equivalent stiffness and achieve the unified coordination between product design and engineering application. It is suggested that the BRB project design should be referred to.

The original foundation of the Urumqi Airport flight area project site is distributed with a 0~4 m thick layer of low moisture silt soil, which has collapsibility. In-situ dynamic compaction treatment at two energy levels of 2 000 and 3 000 kN·m for collapsible loess foundation was conducted, the settlement was systematically monitored during the dynamic compaction process, and the physical and mechanical properties of the foundation soil and standard penetration test data were tested before and after treatment. The effect of dynamic compaction method on treating collapsible loess foundation was analyzed, and recommended design parameters and detection indicators for dynamic compaction treatment were proposed. The results show that the dynamic compaction method can effectively eliminate the collapsibility of low moisture content collapsible loess in the area, significantly improve its compactness and bearing capacity, and meet the post construction settlement control requirements of the airport flight zone after treatment. The collapsibility coefficient should be a mandatory inspection item, and it should be required that the collapsibility coefficient after dynamic compaction be less than 0.015. Pore ratio, dry density, and standard penetration can be used as effective detection indicators for dynamic compaction treatment.

The oscillation of certain third-order nonlinear damped differential equations with coefficients of nonpositive neutral term is studied. By using the generalized Riccati transform technique and Yang inequality, some new sufficient conditions are established under which all solutions of the considered equations either oscillate or tend to zero. These results extend and improve upon several relative results. An example is given to illustrate the main results.

The problem of identifying the source term for the Caputo-Hadamard fractional diffusion equation on the spherically symmetric domain is studied. The exact solution to the problem is obtained by using Laplace transform and inverse Laplace transform. Analytical examination of the exact solution reveals that the problem is ill-posed. On this basis, the Quasi-boundary regularization method is used to solve the stability problem of the solution. Furthermore, two convergence error estimates under both a priori regularization parameter selection rule and a posteriori regularization parameter selection rule are provided respectively. The finite difference discretization method is used to obtain the iterative scheme. The effectiveness and stability of the regularization method are demonstrated through numerical examples.

Based on the nonzero row sums of nonnegative matrices, the classical Gerschgorin disk theorem and Hölder inequality are applied to estimate the spectral radius of a nonnegative matrix, and the expressions of the upper and lower bounds of the spectral radius of a nonnegative matrix are obtained. The proposed methods have good operability and can get tight upper and lower bounds. Finally, the accuracy of the results is verified by specific arithmetic examples.

Let F_q be a finite field of cardinality q, q=2^mand m>1.Assuming that h is a positive integer and coprime with m, for the translation o-polynomial f(x)=x^2h, let C⁽²⁾_H(f) be the binary subfield codes of the hyperoval code C_H(f). Based on the trace function representation of C⁽²⁾_H(f) and the theory of exponential sums over finite fields, the weight distribution of C⁽²⁾_H(f)is obtained. The parameters of C⁽²⁾_H(f) and its dual codeC^(2)⊥_H(f) are determined.