In order to improve the cavitation performance of low-specific speed centrifugal pumps, an impeller model featuring a tandem blade structure was designed. The transient numerical analysis of centrifugal pump employed a modified SST k-ω turbulence model in conjunction with Z-G-B cavitation model. The algorithm was verified by hydraulic characteristic test and cavitation test. A comparative analysis was conducted between the original model and the tandem blade impeller model, focusing on hydraulic characteristics, cavitation characteristics, flow field structure, pressure distribution, turbulent energy distribution, cavity volume, and pressure pulsation. The results show that the tandem blade structure exerts minimal influence on the hydraulic characteristics of the centrifugal pump. However, it effectively suppresses air bubble formation during the development and serious stages of cavitation, thereby enhancing the pump′s cavitation performance. Simultaneously, it inhibits the expansion of the high turbulence kinetic energy region during the initial phase of cavitation, diminishes the intensity of turbulence kinetic energy at the impeller outlet throughout the development and advanced stages of cavitation, and mitigates the formation of low-pressure areas surrounding the rotating impeller. Mitigating the primary frequency amplitude of pressure pulsations at the tongue of the snail shell during both the development and advanced stages of cavitation can effectively suppress the noise and surge associated with cavitation, thereby enhancing the operational stability of the pump.

In order to explore the change law of internal pore structure of mixed sand concrete under accelerated sulfate attack under different environmental conditions, the experimental study on sulfate attack mixed sand concrete under initial injury, mix salt, freeze-thaw cycle, dry-wet cycle, multiple concentrations and high temperature environmental conditions shows that the effect of sulfate attack on the change law of internal pore structure of mixed sand concrete under different environmental conditions is different. With the increase of erosion period, the proportion of harmless pores and less harmful pores under other conditions shows a decreasing trend except that the harmless pores under multiple concentration and composite salt conditions show a slight increase. Compared with the control group, the proportion of harmless holes decreases under the conditions of multiple concentration, initial damage and freeze-thaw cycle, while the proportion of harmless holes increases under the conditions of compound salt, high temperature and dry-wet cycle. The proportion of harmful holes increases significantly under the conditions of initial damage and high temperature, while the proportion of harmful holes decreases under the other conditions. Compared with the control group, the porosity increases by 32 % under the condition of dry-wet cycle, the average pore diameter increases by 3 255.4% under the condition of multiple concentration, and the increase of bound fluid saturation damage and free fluid saturation under the condition of initial damage was the largest.

The start-up process of a mixed-flow pump was optimized using ANSYS Workbench in conjunction with OptiSLang optimization design software. Utilizing quasi-steady state theory and full-domain model calculation data, a response surface surrogate model for the hydraulic performance during the quasi-steady start-up process of the mixed-flow pump was established. The internal flow state was optimized and the vortex-induced energy losses was reduced during the start-up process by using the NSGA genetic algorithm, and thus enhancing the hydraulic performance of the mixed-flow pump. The hydraulic characteristics and blade pressure distribution of the original and optimized mixed-flow pumps were compared, and the internal vortex structure was analyzed, and the feasibility of the proposed hydraulic performance optimization scheme for the quasi-steady start-up process was verified. The research results indicate that the blade inlet angles α₁, α₄, α₅, outlet angles β₁, β₂, β₃, β₄, β₅, blade wrap angle φ, and blade thickness coefficient θ have a significant impact on the weighted average head and weighted average efficiency of the mixed-flow pump. The blade pressure distribution at diffe-rent start-up times was compared, it was found that this method can effectively improve the transient head in the middle and late stages of start-up process.

In order to reveal the evolution of the internal vortex structure in a mixed-flow water jet propulsion pump under cavitation conditions, the Ω vortex identification method was used to identify and study the internal vortex structure under a cavitation number of 0.142. Based on this, the influence of cavitation on the characteristics of vortex structure was investigated, and the contributions of various terms in the vorticity transport equation to the evolution of vortex structure during one cycle were analyzed. The results show that under cavitation conditions, the internal flow of the water jet propulsion pump is complex, and it is extremely prone to generating vortices. The main vortex structures include blade tip leakage vortex, secondary leakage vortex, vertical cavitation vortex, and secondary leakage-derived vortex. As the triangular cavitation collapses, the scale of the inlet attached vortex increases, but the vorticity of the tip leakage vortex gradually decreases due to the increasing size of the cavitation bubble. During one cycle, when the scale of the cavitation bubble in the water jet propulsion pump is relatively large, the scale of vortex structure is large, but the intensity is small. When the scale of the cavitation bubble is small, the scale of the vortex structure decreases and the intensity increases. Through the decomposition of the vorticity transport equation, it can be found that the distribution of the stretch-twist term is highly similar to the distribution of vorticity, and the compression-expansion term has the highest magnitude, which is closely related to the scale of the cavitation bubble and is sensitive to the changes of the vertical cavitation vortex and the shedding vortex. The magnitude of the oblique pressure moment term is higher at the location of the vertical cavitation vortex.

Based on the integrated device of peristaltic pump for preparing and injecting fertilizer, the problem of reduced precision in fertilizer dispensing and injection caused by reflux phenomenon during the operation of peristaltic pump was studied. The structure of slipper in peristaltic pump for the problem that the precision of fertilizer distribution and injection was carried out, the hydraulic performance was tested to reveal the influence law of key structural parameters on fertilizer distribution flow, pump pipe temperature, instantaneous flow and reverse flow coefficient. The results show that under the same pump speed conditions, with the increase of slipper radius, the flow rate of fertilizer distribution decreases gradually, while the temperature of pump tube gradually increases. At the radius of 37.5 mm, the maximum value of 51.3 ℃ is reached, and the average reverse flow coefficient decreases first and then increases, reaching a minimum value of 0.56 at a radius of 30.0 mm. Under the same slipper radius conditions, with the increase of the rotation speed, the fertilizer distribution mixing flow rate increases gradually, and the instantaneous flow rate shows a trend of first increasing and then decreasing. The temperature of the pump tube rises sharply at first and then tends to be stabilize, while the reverse flow coefficient shows a trend of first decreasing and then increasing and then decreasing. The optimal radius of slipper is calculated as 30.0 mm by means of comprehensive score method and entropy weight method. In the end, it is suggested that the 30 r/min speed of peristaltic pump should be set in irrigation system. The experimental results can provide ideas for the research on improving the precision of fertilization in the integrated device of water and fertilizer.

To investigate the axial displacement balance and axial force characteristics of the rotor system in a turbine-type energy recovery integrated machine, the Reynolds-Averaged Navier-Stokes(RANS)method was employed, utilizing the SST k-ω turbulence model to perform a numerical simulation of the entire flow field within the integrated machine. The impact of varying axial clearance sizes on the hydraulic performance of the machine was analyzed. Additionally, the internal flow characteristics and axial force variations were examined across five different axial clearance configurations. The findings indicate that the magnitude of axial clearance exerts a substantial influence on the leakage flow at the turbine end. An augmentation in axial clearance results in a maximum reduction of 8% in turbine end efficiency. Conversely, the hydraulic performance at the pump end is minimally impacted and remains largely stable. Under rated design conditions, an increase in axial clearance leads to a reduction in the average pressure within the front chamber of the turbine end by 0.37 MPa. The axial force of the integrated rotor system is directed towards the turbine end, and the magnitude of this axial force increases by about 5 kN. The research results can provide theoretical guidance for the design and operation of turbine energy recovery integrated machine.

Based on Lighthill′s acoustic analogy theory, a hybrid numerical simulation method was used to analyze the influence of flow variation on the frequency domain characteristics of sound pressure level(SPL)and overall sound pressure level(OSPL)of flow-induced noise in shaftless pump-jet propulsor and its relationship with the internal flow field. The results indicate that the axial passing frequency(APF)is the main frequency, with a high peak at 2 APF. At small and design flow rate, the SPL at APF exhibits an initial decrease, followed by an increase, and then another decrease along the flow direction. While it shows an initial increase followed by a subsequent decrease radially, and there are blade passing frequency(BPF)and its harmonic frequencies in the frequency spectrum. However, the SPF decreases along the flow direction, and decreases first and then increases along the radial direction at large flow rates without BPF and its harmonic frequencies in the frequency spectrum. Meanwhile, as the flow rate increases, the SPL at APF near the impeller gradually increases. While for the case of distant regions, it exhibits an initial increase followed by a subsequent decrease. The OSPL is found to increase as the flow rate increases. Along the flow direction, the OSPL decreases gradually, with a lower rate of noise attenuation rate at large flow rates. The highest OSPL approaches the axis radially with the increase of the axial distance of the radial region. The velocity gradient and the variation of the two vortices in the outlet section near the impeller are the main factors affecting the noise distribution of the shaftless pump-jet propulsor at different flow rates.

An optimization method was proposed in this study for centrifugal pump impeller blade loa-ding using the 3D inverse design. A medium-specific speed centrifugal pump was selected as the research object, and the impeller blades with front-loading shroud and after-loading hub were redesigned using the 3D inverse problem design method without changing its axial projection, blade thickness distribution, and other conditions. The Latin hypercube sampling method was used to establish a sample space of 80 centrifugal pump impeller models, and the centrifugal pump performance was obtained by numerical simulation using Fluent software. By taking the blade loading parameters as the optimization object and the hydraulic efficiency of the centrifugal pump design operating point as the optimization target, the relationship between the blade loading parameters and hydraulic efficiency was established using the Kriging surrogate model. Under the condition that the head met the design requirements, the MIGA algorithm was used to obtain the load parameters of the centrifugal pump with the highest hydraulic efficiency. The results show that in the loading curve, the parameters that have a greater influence on the efficiency are the two intersection points ND_h and NC_h of the straight line and the parabola in the hub, and the intersection point NC_s of the straight line and parabola in the shroud. The parameters with less influence are the leading edge loading LE_h in the hub and the intersection point ND_s of the straight line and the parabola in the shroud. The hydraulic efficiency of the optimized centrifugal pump is increased by 1.35% at the design working point and the efficiency zone is wider. The minimum pressure on the surface of the blades is increased by 38.41% and the cavitation performance is improved. In addition, the power is reduced by 2.46% and the head is slightly improved. The study results provide a useful reference for the efficient design of impeller blades of centrifugal pumps.

To address the issue of gas outflow from the outlet of a vacuum tank and to explore the underlying mechanism of gas-liquid two-phase flow within vacuum tank, the RNG k-ε turbulence model and Volume of Fluid(VOF)model were employed. Analyses were conducted on the gas-liquid interface morphology, gas discharge percentage at the outlet pipe, and flow conditions under different initial conditions. The influence of initial conditions on the internal flow field was investigated, and the relationship between water level and internal flow field/outlet pipe characteristics was examined. Results indicate that when the initial water level is significantly higher than the inlet pipe, the internal flow field of the vacuum tank is substantially optimized. Compared with the original initial water level, the interaction at the gas-liquid interface is reduced. The peak gas discharge percentage decreases from 6.916% to 0.106%, with the average value decreased from 3.442% to 0.027%. The flow pattern in the outlet pipe has been significantly improved, and the low-pressure regions at the top has decreased. Research findings demonstrate that variations in initial water level can affecte the flow field characteristics, gas discharge volume, and outlet pipe flow patterns within the vacuum tank, providing data support for a deeper understanding of internal flow dynamics and vacuum water tank design.

The aim of this work is to reveal the effect of the geometric distribution and structural parameters of xylem perforation plates on vessel hydraulic characteristics. By the computational fluid dynamics(CFD)method, the micro-flow mechanism in the vessels with three perforation plates was si-mulated by a k-ε turbulent physical field with a low Reynolds number combined with the Bernoulli equation. The impacts of the inner diameter, the type of perforation plates, as well as their inclination angle, hole number, and equivalent diameter ratio on water transport in the vessel were examined in terms of the pressure difference, the flow resistance coefficient, and the hydraulic conductivity. By comparing with a simple perforation plate, the pressure drop of the vessel with a reticulate perforation plate increases by 44.2%, and the flow resistance coefficient increases by 53.3%. The pressure drop of the vessel with a scalariform perforation plate increases by 76.5%, and the flow resistance coefficient increases by 92.3%. As other parameters are consistent, the pressure difference and the vessel flow resistance are inversely proportional to the vessel inner diameter, the inclination angle of perforation plates, and the equivalent diameter ratio. Meanwhile, the two parameters are proportional to the hole number. Furthermore, the effect of water transfer on the inclination angle of a simple perforation plate is negligible. The hydraulic conductivity of the three vessels is ordered from high to low as follows: simple perforation plate, reticulate perforation plate, and scalariform perforation plate. The larger the inner diameter of a vessel, the higher the hydraulic conductivity.

With the trapezoidal pier-suspended grid combined energy dissipator situated in the stilling basin as the research object, the RNG k-ε turbulence model and VOF method were used for numerical simulation to study the hydraulic characteristics and energy dissipation effect of the trapezoidal pier-suspended grid stilling basin. This was done in order to address the issue of hydraulic jump energy dissipation with low Froude number. The results show that the trapezoidal pier can effectively reduce the floor pressure and the velocity near the bottom of the stilling basin. The pressure behind the pier is lower than 100 Pa, and the velocity decreases to 0.20 m/s. As Fr increases,the effect of improving pressure and velocity distribution becomes more significant. The maximum vorticity magnitude in the stilling basin is located in the hydraulic jump and rolling area on the steep slope, where there is an obvious vortex core, which is the main area of energy dissipation. The vortex structure in the trapezoidal pier and suspended grid area is discontinuous, which belongs to the weak vortex structure and the energy is partially dissipated. The energy dissipation in the trapezoidal pier-suspended grid stilling basin is mainly composed of three parts: hydraulic jump energy dissipation, trapezoidal pier shear dissipation and suspension grid dissipation, and the energy dissipation rate of the three working conditions is increased by 4.49%, 9.74% and 9.79% respectively compared with the traditional stilling basin, which gives full play to the effect of superimposed energy dissipation of joint energy dissipators. The results can provide reference for the design and research of energy dissipators in similar projects.

In response to the current lack of suitable irrigation machinery in hilly slopes, a self-propelled spraying device suitable for hilly slopes was designed based on the characteristics of tea plantation planting and the terrain features of hilly slopes.Mechanical theoretical analysis on common spraying driving conditions such as straight-line driving, longitudinal climbing, and lateral slope walking of the spraying device were performed. The RecurDyn multibody dynamics software was used to model the device and simulate the driving state of the device under common spraying driving conditions. The simulation results show that the device has good straight-line driving and climbing performance, and can smoothly pass through a maximum 15° transverse slope and a maximum 15° longitudinal slope. A prototype was developed and tested on a real machine. The average driving speed of the prototype was measured to be 1.94 km/h, with good straight-line performance, and a driving deviation rate of 2.88%. It smoothly passes through a longitudinal slope with a slope angle of 13°, and safely and stably travels on a transverse slope with a slope range of 8°-13°, which is consistent with the simulation results and meets the requirements for slope operation of self-propelled spraying devices. This provides a reference for the design and research of subsequent hilly irrigation equipment.

Traditional soil modifiers(such as lime, cement, gypsum, fly ash, etc.)have improved the hydraulic-mechanical properties of soils to some extent, but they have as well damaged the environment to some extent. Taking calcium lignosulfonate(hereinafter referred to as lignin)as modifier, pinhole test, fragment test, sodium ion exchange ratio test, boundary water content test, unconfined compressive strength test, direct shear test, permeability test, and nuclear magnetic resonance porosity test were carried out to study the effects of lignin content, dry density, and water content on the disper-sibility and hydraulic-mechanical properties of natural dispersive soil. The results show that when the lignin content is 3% and 4%, the modified soil sample is non-dispersive, and the higher the dry density, the worse the dispersibility. With the addition of lignin, the liquid limit, plastic limit and plastic index of soil samples decrease. When the content of lignin is 2%, the unconfined compressive strength, shear strength, and permeability of soil samples experiences best improvement, but when the content of lignin is too large, the hydraulic-mechanical characteristics of soil samples become worse. T₂ spectrum presents a bimodal structure. With the increase of lignin content, the main peak gradually moves to the right, the small pore size of soil samples becomes larger, and the number of large pore sizes increases.

Axial-flow(tubular)pumps are widely used in the construction of pumping stations such as China′s South-to-North Water Diversion Project and “the Belt and Road Initiative”. In order to study the influence of fluid exciting forces on system vibration of large-scale axial-flow pump under several ope-rating conditions, CFX and Mechanical were combined to conduct the numerical simulation of the fluid-structure coupling, as well as the flow-induced unsteady stresses on the blades of the pump impeller. The fluid domain was resolved based on the N-S equation with the RANS method, and the solid domain was calculated by adopting the dynamic equation of elastic structure. The deformation, stress distribution and modal characteristics of the pump rotor were obtained using the arbitrary Lagrange-Euler(ALE)method. The results show that the blade-passing frequency is consistent with the frequency of pressure fluctuations, and the impeller rotation is the main reason for the pressure fluctuation. The maximum deformation on the blade appears at the blade tip, and the maximum stress on the blade occurs at the juncture between the blade and the hub. Within the range of 0.6-1.4 times of the rated speed of the impeller, it is difficult to find a reasonable speed that maintains a certain difference between the natural frequency of each order of the rotor and the blade-passing frequency(or its multiple frequency). However, after ignoring the possibility of secondary resonance, there is an optimum speed to achieve a reasonable difference between the natural frequency and the main frequency of each order.

To understand the influence of wind speed profile distribution determined by atmospheric stability on the operational characteristics of wind farms, a numerical weather prediction model incorporating a coupled wind farm parameterization scheme was developed to investigate the wake effect and the power generation characteristics of large wind turbines within large wind farms under varying atmospheric stability conditions. The results show that wind farm exhibits pronounced wake effects under stable atmospheric boundary conditions. Furthermore, as the atmosphere turns from instability to strong stability, there is a discernible trend of increasing wake intensity. In addition, the mutual interference between upstream and downstream wind farms is significantly more pronounced within a stable atmospheric boundary layer. Under stable boundary conditions, the power output of the wind farm exceeds the average power output by approximately 4%.Conversely, under unstable boundary layer conditions, the power output is reduced by approximately 9% relative to the average power output. Furthermore, surface shear stress and atmospheric stability significantly influence the power output of wind turbines. Under unstable atmospheric boundary conditions, atmospheric stability serves as a critical evaluation parameter for wind power. Consequently, the traditional approach of considering only the impact of wind shear on power output is insufficiently comprehensive.

In order to improve the throttling performance of the throttle valve under high sulfur conditions, a sleeve choke valve was taken as the research object, and the 3D Euler-Euler multiphase model combined with the standard k-ε turbulence model was applied to investigate the gas-solid twophase flow within a sleeve choke valve. The velocity field distribution, turbulent viscosity field distribution, flow characteristics and flow resistance characteristics under different valve openings, throttling hole structures and sizes, and inlet particle solid content were analyzed and afterward 〖JP2〗compared with the experimental results. The results show that the flow velocity within the equilateral nozzles decreases with the increase of the valve opening, which can alleviate the erosion wear on the nozzle wall and facilitate the flow of fluid inside the throttle valve. The velocity and pressure within the equilateral triangular nozzles change significantly in comparison with other nozzle structures. The core area of the opposing jet near the nozzle outlet is much longer, resulting in the severe erosion wear area close to the outlet of the throttle valve. In addition, 〖JP2〗the interaction frequency between sand particles increases with the increase of the solid concentration. The intensity of the vortex flow existing near the inlet of nozzles is slightly weakened, which significantly affects the overall flow performance and erosion wear of the throttle valve.

To address the discrepancy between the spatial arrangement of pump unit equipment and the optimization of pump device performance, a novel design approach utilizing a wide-body vertical shaft was proposed. Utilizing the three-dimensional turbulence numerical calculation method in conjunction with entropy production theory, the hydraulic characteristics between a wide-body vertical shaft inlet channel and two conventional conical vertical shaft inlet channels were compared. A prototype of a wide-body vertical shaft inlet water pump was developed and fabricated, and its energy performance, cavitation behavior, and runaway characteristics across five different blade angles were evaluated. The findings indicate that the internal flow field of the wide-body vertical shaft configuration closely resembles that of the other two configurations, exhibiting a flow velocity uniformity of approximately 95% and a weighted average angle exceeding 89° under the design flow conditions. The hydraulic losses remain consistent across different flow conditions, with entropy production in the front section of the vertical shaft constituting merely 7.470% of that observed in the rear section. Moreover, the broad profile of the front section of the vertical shaft does not influence the energy dissipation within the flow channel. At a blade angle of 0°, the water pump device achieves an efficiency of up to 79.19%. The critical cavita-tion margin for the pump device with five different blade angles is below 6.0 m. At a blade angle of -6°, the maximum runaway speed, with a head of 2.36 m, is 278.6 r/min. The hydraulic characteristics of wide-body vertical shafts closely resemble those of traditional vertical shafts, while also posses-sing the capability to concurrently satisfy the demands of equipment configuration and pump device performance.

 

Use the acoustic vibration signal for the engine fault diagnosis process, some fault excitations only express a strong response in the specific vibration on the engine surface, and the vibration measurement points require high requirements with contact measurement, which is difficult to achieve under some scenarios. Therefore, a diesel engine intake fault and gear fault diagnosis method is proposed using surface radiated sound as the medium and adaptive variational mode extraction(AVME)as the preprocessing method. Bench experiments were carried out under three fault conditions of a 6-cylinder in-line heavy-duty diesel engine, namely: air filter blockage, abnormal valve clearance and timing gear damage, and the engine surface acoustic signal under different fault degrees was obtained. Based on the improved AVME method, the optimal decomposition of the intrinsic mode function(IMF)of the acoustic signal is achieved. By calculating the mutual relationship between IMF and the original signal, the highly correlated IMF is extracted to constitute the classifier input. By AVME, the fault acoustic features are effectively enhanced, and input into the support vector machine model optimized by sparrow search algorithm(SSA-SVM), and the collaborative optimization of feature parameters and model parameters can achieve better diagnosis accuracy. The experimental verification results show that without the need for testing in a semi-anechoic chamber, only a single-channel acoustic signal is used to diagnose three types of 11 degrees of the intake system and gear faults, the accuracy rate of the front-end acoustic and the top-side acoustic signals are the highest(98.89%)and the lowest(88.78%), respectively. After using the front, top, and rear acoustic data, the diagnostic accuracy rate can reach 99.57%. The research results provide a reference for engine fault diagnosis based on non-contact measurement methods such as acoustic signals.

According to the relevant requirements of the national standard ″Submersible Plug-Flow Mixer″(GB/T 33566—2017), the inspection of submersible mixers must be carried out in an annular inspection water tank. However, the annular inspection tank is expensive and it is difficult to measure the water velocity. As a result, the current research on the flow field characteristics of submersible mixers lacks strong experimental support. Therefore, by taking QJB7.5/12-620/3-480/S submersible mixer as the research object, flow velocity experiments based on an existing annular detection pool of Shaoxing Quality Inspection Institute were conducted, and compared the full flow field comprehensive numerical simulations performed by CFD software. It is concluded from the study that within the stan-dard pool flow field range of the submersible mixer, the flow characteristics of the test and calculation are highly similar. In the effective push flow section of the submersible mixer, the velocity in the central area increases first and then decreases with the increase of the advancing distance, and the flow velocity reaches a maximum value of about 0.600 m/s near the propulsion distance of 5.0 m. Due to uneven flows causing some deviation in axial push flow for the submersible mixer, both sides of the channel exhibit relatively gentle water velocities. However, water velocity on the outer wall side is lower than that on the inner baffle side. In this experiment, when the advancing distance reaches 15.0 m, the velocity at all measuring points is lower than 0.300 m/s. Combined with numerical calculation results, the equi-valent effective push flow length of this model of submersible mixer is 13.64 m, with an equi-valent effective volume of 218.24 m³. It exhibits a specific power consumption rate(SPCR)of 32 units. Furthermore, the average flow velocity within the annular pool is approximately 0.153 m/s. The research fills the gap in the flow experiment of submersible mixers, promotes the implementation and continuous improvement of relevant standards, and has great significance for the performance cognition and future development of submersible mixers.

The deformation of panel rockfill dams is influenced by external loads and internal material creep. The presence of an excessive number of influencing factors can lead to feature redundancy and result in overfitting, thereby compromising prediction accuracy. Conversely, a lack of sufficient factors may lead to incomplete information representation, causing poor predictive performance and limited model generalization ability. Hence, it is crucial to build a comprehensive and interpretable set of factors to optimize them accordingly. To address these challenges, a predictive model for the deformation of panel rockfill dams utilizing an integrated factor optimization algorithm was introduced. ReliefF and Shapley additive explanations(SHAP)algorithms were employed to rank the importance of factors through weighted integration. Subsequently, non-essential factors were eliminated based on an analysis of the threshold of cumulative contribution rate differences, leading to the identification of key factors. By taking a concrete panel rockfill dam in Xinjiang as the research object, the feature shrin-kage rate(FRR), normalized mean absolute percentage error(nMAPE), mean absolute error(MAE), mean square error(MSE), and coefficient of determination R² were used as the evaluation indexes. The experimental results show that the algorithms proposed in the paper can accurately obtain the best factors in the face of different prediction models, which can effectively improve the prediction accuracy. Compared to conventional factor optimization techniques, the proposed approach exhibits greater adaptability and delivers more significant predictive enhancements, effectively addressing issues related to inadequate prediction capability caused by either redundant or insufficient influential factors. Furthermore, it enhances the generalization capacity of the model and offers an efficient method for optimizing factors in research pertaining to dam safety monitoring.

In order to evaluate the high-temperature oxidation behavior of GH4169 alloy under in-ser-vice conditions, the high-temperature oxidation behavior tests of GH4169 alloy under different processes were carried out, for which the different processes carried out were laser shock, heat treatment, and combined laser shock and heat treatment processes. The morphology of GH4169 alloy under the diffe-rent treatment conditions was analyzed by a transmission electron microscope(TEM), and the oxide composition was characterized by X-ray diffraction(XRD). The surface morphology, cross-sectional morphology, and oxidation product composition of the samples were analyzed by scanning electron microscopy(SEM)and X-ray energy dispersive spectroscopy(EDS). The results show that high density of dislocations and grain refinement can be induced after laser shot peening, which can accelerate the formation of oxide film in the initial stage of oxidation. After compounding with heat treatment, the precipitation phases of the alloy are generated. These precipitation phases play an important role in inhibiting the generation of needle-like spinels during the oxidation process, resulting in a more continuous and dense oxide film under the composite process. Finally, the oxidation kinetic curves were combined to reveal the growth mechanism of the oxide film after the combined treatment of laser impact strengthening and heat treatment.

The forward intake forebay of the pumping station,utilizing a multi-sediment sand river as its water source, encounters issues including sediment deposition, reduced operational effciency of the pumping station, etc. This study focus on the forward intake forebay of a pumping station in the Jingtai Chuan electric power lifting and irrigation project in Gansu Province as the object of investigation. Design the body structure of the arc diffusion-type forward intake forebay and carry out numerical simulation utilizing Fluent software based on the realizable k-ε model and the mixture multiphase flow model to obtain the distribution characteristics of sediment concentration. The distribution characteristics of sediment concentration in the arc-diffusion forward intake forebay were analyzed and to reveal the influence of the degree of contraction of the arc-diffusion side wall on the movement characteristics of water and sand in the forebay. The results show that, in the vertical flow direction of water flow, the sediment volume concentration distribution in the forebay of the circular arc diffusion type exhibits a lower concentration in the middle and high concentration on both sides. In the water depth direction, the distribution of sediment volume concentration in the forebay gradually increases from the surface to the bottom. In comparison to the linear diffusion type forward intake forebay, the area of high sand content in the circular arc diffusion type forward intake forebay with a center angle of 44° is reduced by 41.77%, and the sediment siltation is reduced by 43.60%. These findings offer valuable insights and guidance for the optimization design of the forebay of the same type of pumping stations, thereby contributing to enhancements in the engineering quality and operational efficiency of pump station infrastructure.

In order to solve the problems of water hammer and uneven irrigation outflow during valve closing of large-scale irrigation pipe network in Kelamayi City, Xinjiang, based on the one-dimensio-nal method of characteristics, a hydraulic model of pipeline network was established by using Flowmaster software to study the transient flow characteristics of pipeline network under different valve-closing laws and the influence of valve-opening disturbance on pipeline network flow uniformity. The research results show that the comparison error between the predicted hydraulic characteristics of the model and the design parameters of the pipeline network does not exceed 8%, which verifies the accuracy of the model. For the transient hydraulic characteristics of the pipeline network operation, one-stage linear closing laws with different total durations ranging from 20 to 60 min were adopted to control the closing process of the main valve in the pipeline network system. Even if the valve is closed for up to 60 minutes, cavitation phenomenon still occurs in the pipeline section of the pipeline network. Two-stage valve-closing law of fast closing followed by slow closing with the total valve closing duration of 30 min was studied, and the fast closing time is 10 min when the opening degrees of fast closing are 65%, 75% and 85%, respectively. Under the fast closing opening degree of 85% and slow closing opening degree of 15%, there is no cavitation in the pipeline section, and the maximum water hammer pressure in the pipeline is less than the design pressure of the pipeline. For the flow-rate uniformity caused by pressure fluctuation of the pipe network, the pressure fluctuation was simulated by valve-opening disturbance. When the valve-opening is adjusted from 100% to 90%, the average reduction rate of the flow rate at the head end of each branch pipe is 0.079% with small flow rate fluctuation. The average decrease in flow rate at each outlet pile is 0.074% and the Christensen coefficient is 0.989 9, indicating good irrigation uniformity. The research results can provide guidance for the analyses of water hammer protection and valve-opening disturbance on the flow uniformity of large irrigation pipelines.

Prevailing Bayesian parameter inversion techniques have often been marred by extended computational durations, diminished computational precision, and sub-optimal accuracy. Hence, a hybrid surrogate model underpinned by the multiple attempts of differential evolution adaptive Metropolis(MT-DREAM _(ZS))algorithm was introduced, which offered a more scientifically grounded approach for determining the weight coefficients of individual models, and was modified through Pareto optimization-based dynamic weight coefficient multi-objective optimization. Three distinct machine learning methodologies including multivariate adaptive regression splines, artificial neural network random forest, and random forest were integrated into the Bayesian framework to establish a composite model. Additionally, the posterior distribution of seepage parameters was deduced, while thoroughly accounting for uncertainties present in the inversion procedure. Combined with the monitoring data of the actual project, the gap between this combinatorial agent model and other models was compared and analyzed by calculating the prediction performance index R² and RMSE. Research findings substantiate that the hybrid surrogate model, coupled with the novel technique for weight determination of individual models, boasts superior fitting precision and predictive efficacy. Compared with the traditional method, the improvement rate is 15%-20% on average. By applying the inverted seepage parameters to simulation experiments, a new approach is provided for the development of dam seepage detection research.

In order to improve the fertilizer absorption performance of the existing largediameter Venturi fertilizer injectors, the structure optimization design was carried out. Based on the large-diameter symmetrical Venturi fertilizer injector(M-type), and it was modified and designed as an eccentric Venturi fertilizer injector(P-type). Orthogonal design method and numerical simulation technology were applied, and the absorption efficiency was used as the evaluation index to determine the optimal combination of structural parameters of the eccentric Venturi injector. Experimental testing and numerical simulation comparative analysis were conducted on two types of fertilizer applicators. The result shows that the optimal combination of structural parameters is a throat inlet diameter d₁(17 mm)、a diffusion angle β(3°)、a throat outlet diameter d₂(20 mm)、a straight section length L₂(16.6 mm)、a throat groove diameter d(27 mm)、a throat groove width L₁(4 mm)and a contraction angle α(23.5°). Through experimental tests and comparative analysis, it is found that the optimized P-type injector increases the maximum fertilizer absorption flow rate by 21.4% compared to the maximum suction flow of the M-type injector. When the inlet pressure is 0.25 MPa, the maximum fertilizer absorption concentration is increased by about 30.7%, and its maximum fertilizer absorption efficiency is increased by about 13.9%. Flow field analysis shows that compared with the M-type fertilizer injector, the P-type injector is less prone to cavitation under the same pressure difference, and the flow pattern of the P-type Venturi injector is more stable and its energy loss is smaller. The preceding research demonstrates that the optimized eccentric Venturi fertilizer injector can improve the fertilizer absorption performance.

In order to improve the pulse characteristics of the jet tee suitable for non-rotating refractive nozzle, an orthogonal design method was adopted and used to select 4 factors: nozzle width, position difference, laying length, and side wall angle. Each factor had 5 horizontal parameter levels, and a total of 25 different structural models of the jet tee were designed. CFX numerical simulation software was used to carry out CFD numerical simulation calculations on 25 groups of jet tee models. The head amplitude and head loss were taken as performance evaluation indicators to determine the primary and secondary order of influence of each factor on performance indicators and the optimal structural size model. Comparing the pulse characteristics of the optimized model with those of the ordinary model, the simulation results show that the head amplitude of the optimized model is increased by 0-16.73 kPa, and the head loss is decreased by 0-3.34 kPa. After hydraulic performance tests, the results indicate that under working pressures of 0.10, 0.15, and 0.20 MPa, compared to regular tees, the peak sprinkler intensity of the refraction sprinkler is reduced by 41.50-69.07 mm/h under jet tee conditions, while also improving water distribution near the sprinkler. The uniformity coefficient of sprinkler combination was calculated by superimposing the water volume of a single sprinkler through Surfer software. The results show that compared to regular tees, the refraction sprinkler combination under jet tee conditions can increase the irrigation uniformity coefficient by 1.7% -23.1% at sprinkler spacings of 2.0, 2.5, and 3.0 m.

The diagnosis of vibration signals of pump unit is very important for the safe and stable ope-ration of the units. Based on EEMD decomposition and multi-scale permutation entropy and multi-strategy optimization algorithms, a pump unit fault diagnosis model was proposed. The original signal was decomposed and reconstructed by EEMD, and then the multi-scale permutation entropy group of the reconstructed signal was calculated as the feature set, and finally the DBO-BP fault diagnosis model was established. Aiming at the problems of DBO algorithm, such as easy to fall into local optimal solution and slow iteration speed, three methods, such as Lévy flight, chaotic mapping and adaptive t-distribution were used to optimize the Dung Beetle algorithm, and finally a new model of LCTDBO-BP was obtained. In order to explore the performance of the optimized model, a variety of dimensional functions were introduced for re-analysis. The results indicate that the proposed model has significant advantages under unimodal and multimodal functions. At the same time, the rotor fault platform data was used to simulate the typical faults of the pump unit and verify the fault classification. The simulation results show that the accuracy of the model reaches 98%, which is 8% higher than that of the unoptimized model. This study provides a new methods for diagnosing fault of pump units.