For water supply systems with high-lift, the pump-stopping water hammer caused by the power failure is usually greater than the direct water hammer caused by the check valve closing. Based on the Joukovsky equation and the pressure drop law behind the pump, the influence of the check valve closing law on the pressure along the pipeline was studied, and the theoretical value of the optimal closing time (i.e., T_g=T_d) was obtained when a pump trip occurred. The theoretical value was verified by numerical simulation through a practical project. The results show that for high-lift water supply projects, the theoretical closing time of the check valve can minimize the pressure drop along the pipeline when the pump trip occurred.

Aiming at the falling into locally optimal solution shortcomings of optimization algorithm and probability density method for inversion of river cross-sections in ungauged regions, this paper proposed a combination of Ensemble Kalman Filter (EnKF) method and particle swarm optimization algorithm (PSO). The PSO was used to initialize the missing section to form a trapezoidal initial section. Then the EnKF was used to correct the initial section, and the proposed method was verified by the ideal case. The results show that the R² and N_NSE of the model are higher than 0.99, and the relative mean square error is less than 0.04. Considering the observation errors in the engineering practice, the observation errors of 0.1%, 1%, 5% and 10% were selected to evaluate the hydrodynamic simulation errors of the missing section, the PSO initial section and the corrected section by the EnKF method. It is found that the errors are normally distributed with the selected errors, but the overall distribution is normal with different errors. But the EnKF method can maintain a high simulation accuracy with different observation errors, the R² is higher than 0.98, the relative mean square deviation (RMSD) is less than 0.06 m, and the N_NSE is higher than 0.98. Thus, the proposed method has a high feasibility.

Under the background of building a new-type power systems, the hydro-thermal-wind-solar-storage system with a high proportion of new energy has become the main research object of power system planning. It is necessary to perform high-frequency iterative calculations on the long-term supply-demand balance of the hydro-thermal-wind-solarstorage system to achieve quantitative analysis of sensitive boundaries, which puts forward higher requirements for the calculation efficiency of the analysis method. Considering the working characteristics of various power sources and the output probability characteristics of new energy sources, this paper proposed a heuristic unit commitment algorithm based on operating rules, which realizes the daily determination of the unit start-up mode throughout the year, and further constructed a supply-demand balance model. Finally, a case study based on a regional power grid example proved that the proposed model and method were feasible and effective, which provides reference for analyzing long-term supply-demand balance of the hydro-thermal-wind-solar-storage system.

Taking double-discharge building in branching stream of Baiyang Lake as an example, the relationship between water level and discharge capacity of only spillway gate and overflow weir was determined by model test, and then the mutual influence between them was determined by numerical simulation. The method of combined model test and numerical simulation to determine the diversion ratio and discharge capacity were explored. Through this method, the diversion ratio of the spillway gate and the overflow weir and the water level under the gate and weir were obtained. Compared with the design value, the difference is very small within 6%. The results show that the discharge capacity of the spillway gate and overflow weir mainly meet the requirements.

The deicing effect of wind turbine blades was tested and analyzed based on the air-thermal method. The thermal conductivity efficiency of the paving structure and the influence of blower speed (or frequency) on the deicing efficiency were mainly considered. Firstly, the blade structure and layering structure were introduced, and the thermal conductivity was estimated by measuring the thickness of the layering structure. According to the ice-covered position of the blade in winter, the rationality of the thermal conductivity distribution of the blade during air-thermal deicing was verified. After that, the field blade deicing test was carried out by changing the speed (or frequency) of the blower. The test results reveal the root cause of the unbalanced deicing phenomenon in the process of wind turbine blade deicing by air thermal deicing system. It shows that the higher the speed (or frequency) of the blower is, the better the deicing equilibrium of the blade surface and the more significant the deicing effect are under the premise of ensuring the temperature stability of the outlet of the ventilation pipe. In addition, with the use of larger blower frequency, the internal circulation of the blade was enhanced, and the reasonable setting of the internal circulation structure of the blade can effectively improve the de-icing efficiency and reduce the de-icing consumption time.

Aiming at the problems of difficulty in determining the optimal parameters and low accuracy of the deep learning method in dam prediction, the sparrow search algorithm (SSA) was improved, and the parameters of the gated recurrent unit (GRU) were optimized by the improved sparrow search algorithm (ISSA). Then a dam deformation prediction model based on the ISSA-GRU was constructed, and this model was applied to the deformation prediction of the Longyangxia Dam of Qinghai Section in the upper reaches of the Yellow River. The results show that the dam deformation prediction model based on ISSA-GRU has higher prediction accuracy and stability, which can be used as a reference for dam deformation prediction.

The high penetration of distributed renewable energy aggravates the power fluctuation and uncertainty of distribution network. In this paper, a two-stage optimal operation strategy of distribution network based on multi-objective reduction and multi-step reconfiguration was proposed. In the day-ahead stage, multiple operational flexibility index models of voltage deviation, power loss, total operating cost, net load peak-valley difference and net load coefficient were constructed. On the basis of the model, a multi-flexibility index dimension reduction method based on target correlation was proposed, which aims to balance the relationship between various indicators, reduce the number of targets and improve computational efficiency. In the intraday phase, a distribution network reconfiguration method based on multi-step switch sequence exchange was proposed by cooperatively controlling the sectionalizing switches and tie switches, which fully exploits the available flexibility resources of the system. Finally, the simulation of arithmetic cases based on the IEEE-33 node system, the IEEE-84 node system, the IEEE-119 node system and the IEEE-136 node system were carried out, and the results show the effectiveness of the proposed two-stage distribution network flexibility enhancement strategy.

The study of groundwater chemical varieties has a positive indicator effect on the regulation and improvement of regional groundwater quality caused by infiltration in the Yellow River Irrigation Area. The field in-situ infiltration test was carried out to monitor and analyze the recharge water-groundwater during the recharge process of paddy field and dry field, and the groundwater chemical evolution law was revealed by AquaChem hydrochemical analysis and SPSS mathematical statistics. Under the condition of infiltration, the characteristics of groundwater chemical change show four evolution processes: "rapid change and active zone in the early stage, gradual transition zone in the middle stage, gentle and stable zone in the late stage, and potential recovery zone after stopping irrigation". It can be seen from the experiment that the groundwater is mainly affected by the physical mixing of recharge water, accompanied by the water-rock physical adsorption ion exchange, chemical dissolution and leaching, etc. especially, the amount of recharge water in paddy field was large, and the water quality of recharge determined the direction of groundwater chemical evolution. At the same time, the concentrations of Na⁺、Cl^- of groundwater chemical components showed a good linear change, and the correlation coefficient was above 0.93, and the concentrations of Ca²⁺、Mg²⁺ showed a certain linear correlation with SO₄^2-、HCO₃^-. After stopping irrigation, the evaporation and concentration of groundwater was strong, and the ions of groundwater showed an increasing trend. Especially for Na⁺、Cl^-, the drainage and precipitation are timely needed after the irrigation. The research shows that the water supply of groundwater not only enriched groundwater sources, but also improved groundwater quality.

Concrete faced rockfill dam is widely used and rapidly developed in water conservancy and hydropower construction in China. This paper optimized the design method of concrete face dam based on BIM technology, realizing the dynamic comparison and selection of toe slab alignment by visual comparison and selection, achieving dynamic calculation of structural stress by structural parametric design and dynamic decision of dam excavation and filling through module-drawing-chart correlation measurement. As the result of dynamic design method, the model was applied to engineering digitization. Then the method was applied to the design of Gaopingqiao Reservoir face dam. Through the development of BIM plug-in, visual programming and customized intelligent cross section, it has played a role in improving the quality and efficiency of toe slab alignment, BIM-FEM joint analysis and zoning quantity calculation. In addition, the lightweight delivery of the model results supports the "intelligent application of Gaopingqiao digital reservoir" and gives full play to the value of the whole life cycle of BIM.

In response to the evident phenomena of flow separation and backflow, low efficiency, and increased cavitation in the tailrace conduit of the Deneng Xiangjiang Hydropower Station after expansion, computational fluid dynamics (CFD) analysis was employed. Two methods, namely, modifying the shape of the tailrace conduit or replacing the runner, were proposed to improve the flow pattern within the tailrace conduit. Research has demonstrated the effectiveness of both methods, which can provide reference for similar projects.