In order to improve the prediction accuracy of ultra short-term wind power, a combined wind power prediction model based on IEWT-FE-BO-LSTM was proposed. Firstly, an improved empirical wavelet decomposition (IEWT) was used to decompose the historical wind power data. The Fuzzy Entropy (FE) algorithm was introduced to calculate the complexity of each decomposed submodel and reconstruct the submodel. For each recostructed component, a prediction model based on long short term neural network (LSTM) was established. Bayesian optimization algorithm (BO) was used for hyper parameters to solve the problem of poor training results caused by manual parameter adjustment. The example analysis based on historical wind farm data shows that the IEWT-FE-BO-LSTM model has high prediction accuracy and efficiency for ultra short-term wind power.

A large area of tensile stress in the middle and lower part of the upstream of a stone-masonry arch dam exceeds the standard and needs to be strengthened. Based on two local reinforcement schemes of a masonry dam, the contact element was used to simulate the joint characteristics of the new and old dam bodies, and the stress and deformation characteristics of the joint surface under five standard working conditions were analyzed. The results show that after reinforcement, the opening and loading characteristics of the joints of the two schemes are similar, and the side pier of the rib pier scheme has asymmetrical opening and loading phenomenon. Under the condition of high water level, the reinforced structure mainly supports the load at the upper part, and the stress at the lower part is small and may open. Under the condition of low water level, the stress level of the joint surface is low and the reinforced structure does not bear the load. Under the condition of temperature drop after reinforcement, the masonry dam body rotates and deforms with the upper part of the reinforced structure as the fulcrum, and the joint surface will open in a large area under the condition of low water level. Under the condition of temperature rise, the dam body shifts upstream when the water level is low, resulting in a symmetrical and smooth parabolic clearance distribution on the horizontal direction.

To ensure the safe and stable operation of large radial gate in service, taking the hydraulic radial gate of Gezhouba Project as an example, the finite element analysis software was used to analyze the static strength and modal to obtain the maximum stress concentration point and deformation of the gate under the design head condition. The vibration intensity of the gate was judged according to the natural frequency, vibration model and maximum deformation displacement. The results show that the deviation between the total design water pressure of the gate and the theoretical calculation is 4.7%, which is located in the 5% error control range. The overall maximum stress of the radial gate is 373.86 MPa and the deformation is 12.938 mm, meeting the design requirements of the specification. The bottom of the panel exists local stress concentration, the overall vibration deformation of the gate is less than 0.508 mm, and the vibration intensity is small. Only low-order frequencies appear in the high-energy region of the pulsating pressure of the water flow, and the possibility of resonance is small.

In order to analyze the flow characteristics of the plane S-type axial extension tubular pump unit, the software CFX was used to conduct three-dimensional full channel numerical simulation, and the energy gradient theory was used to analyze the flow characteristics of pump unit under different working conditions. The results show that under different flow conditions, the water flow in the inlet passage of the plane S-type axial extension tubular pump is very smooth, and the overall difference is small. The flow pattern in the outlet channel is quite different, and the smaller the flow rate is, the worse the flow pattern in the outlet channel is. The pressure pulsation at the same position in the plane S-type axial extension tubular pump unit is the largest under low flow conditions. The difference of energy gradient in the outlet channel is the largest under the condition of small flow, which indicates that a large energy loss will occur in the outlet channel under this condition. When designing the outlet passage of the plane S-type axial extension tubular pump unit, the length of the smooth section of the outlet passage should be increased as much as possible to ensure the uniform distribution of energy gradient. The research results can provide theoretical guidance for better understanding of the plane S-type axial extension pump device and optimization design.

To explore the microseismic evolution characteristics of instability failure of surrounding rock of deep buried tunnel, biaxial compression tests of granite were carried out under different intermediate principal stresses (σ₂). The microseismic monitoring system and high-definition camera were used to monitor and record the failure of granite in real time. The evolution characteristics of microseismic b value and dominant frequency of rock failure process under different σ₂ conditions were analyzed, and the index of microseismic energy release (MSER) was proposed to describe the degree of rock failure. The results show that with the increase of σ₂, the cumulative microseismic energy release, the maximum value of lgN/b and the ratio of low frequency signal before rock failure, and the microseismic energy release rate at rock failure time all increase, while the minimum value of b value before rock failure decreases. In addition, the microseismic precursor of rock instability lists as follows: b value drops to less than 0.8; lgN/b rises to more than 3; High amplitude and low frequency signal appears. The precursors of rock slabbing are high amplitude low frequency signals accompanied by a small number of high amplitude high frequency signals, while the precursors of rockburst failure are that b value drops to less than 0.5, and lgN/b rises to more than 5, and high amplitude signal only appears in the low frequency band.

Analysis of rock fracture seepage plays an important role in evaluation of rock engineering safety. The three-dimensional coordinate points of the rock fracture surface were scanned by a three-dimensional structure optical scanner and visually reconstructed. Parameters such as joint roughness coefficient JRC and topography statistics were used to quantitatively describe the roughness and undulation characteristics of rock fractures. Through experimental research, it is found that when the seepage pressure gradient increases, the seepage in rock fractures will change from linear seepage to non-linear seepage, and the Forchheimer formula can better fit this process. The threshold and Reynolds number of the critical Darcy flow were obtained by introducing he nonlinear factor E. The relative loss of momentum-Euler number was introduced to study the law of fluid energy evolution in the process of fracture seepage. It is found that the Euler number shows a trend that first drops rapidly and then gradually stabilizes. The result has certain guiding significance for actual engineering.

Aiming at the inability to accurately locate the fault of the transmission line in hydropower station, an improved double-end location algorithm independent of wave velocity was derived from the actual propagation theory of traveling waves. Using the unique advantages of variational mode decomposition (VMD) which can adaptively decompose fault current traveling wave signals, and the Teager energy operator (TEO) which can quickly track the energy change of signals and has less computation, a traveling wave positioning model for 220 kV transmission lines based on VMD-TEO was established. The model does not need to consider wave velocity correction and double terminal time synchronization. The simulation results of PSCAD show that the maximum error percentage of the improved double-end fault location model is 0.239%, which is superior to other location algorithms. The reliability and superiority of the proposed method were verified.

To analyze the applicability of CMORPH merged hourly gridded precipitation product in Northern China, the statistical indicators between the observed grid precipitation and CMORPH merged gridded precipitation in temporal and spatial distribution of flood season from 2008 to 2012 were evaluated in the Yihe River Basin. Using the two precipitations as the input of HEC-HMS model, the feasibility of floods forecast of the CMORPH merged precipitation was evaluated. The results show that the CMORPH merged precipitation has a high correlation with the observed grid precipitation, and the flood simulation accuracy is comparable to the result of observed grid precipitation, and performing better in the simulations both runoff volume and flood peak. The satellite merged precipitation has good applicability in flood forecasting in the study area.

In order to study the influence of mineral admixture on steam-cured concrete under freeze-thaw environment, CT technology was used to scan the steam-cured concrete after freeze-thaw cycle, and the sectional images were obtained. The three-dimensional reconstruction of steam-cured concrete was carried out by Fiji and Avizo software, and the pore structure characteristics of the samples were obtained. The results show that the compressive strength of steam-cured concrete decreases with the increase of freeze-thaw times, and the deterioration of pore structure is the main reason for the decrease of compressive strength; The mechanical properties and pore structure characteristics of steam-cured concrete mixed with mineral powder and fly ash are better than those of ordinary steam-cured concrete under the same freeze-thaw conditions. The mineral powder and fly ash have a certain effect on improving the pore structure of steam-cured concrete.

Using the daily meteorological dataset of basic meteorological elements of China National Surface Weather Station (V3.0) as a control, the reproducibility of the spatial and temporal distribution characteristics of hourly precipitation in North China during the warm season (June-September) by the China Hourly Merged Precipitation Analysis (CHMPA) and the CPC MORPHing technique (CMORPH) were compared and analyzed. The hourly precipitation and daily variation characteristics of the warm season in North China were further investigated. Results show that the spatial and temporal distribution of precipitation in CHMPA and CMORPH during 2008-2018 is basically consistent with the observation, the estimation of precipitation by CHMPA is generally smaller than the observation, while CMORPH is larger than the observation. The CHMPA data has high spatial resolution and little difference with the actual observation, which is more conducive to the diagnosis analysis of strong convective weather. The overall warm season hourly precipitation in North China is characterized by more precipitation in the southeast and less in the northwest, with normal rain mostly occurring in the plateau area and flash heavy rain mostly occurring in the transition area between the plateau and the plain and the plain area. The warm season precipitation in North China has obvious daily variation characteristics. The large value of precipitation center appears in the afternoon near the mountains, then gradually moves southeast and causes large precipitation in the western part of the North China Plain at night, and the precipitation center reaches the central part of the plain in the early morning of the next day. The precipitation gradually weakened in North China from early morning to noon the next day. The peak of precipitation and precipitation frequency occurs mostly from midday to late afternoon in the plateau area and from midnight to early morning in the plain area. The results provide a theoretical reference for precipitation research and forecast in North China.