Abstract:The human-water relationship is one of the most important relationships between human and nature. The human-water relationship discipline is a new interdisciplinary subject that studies the human-water relationship. Developing basic equations and models is one of the core contents of in-depth research on human-water relationship. Based on previous research and interdisciplinary findings, this study proposes the “four processes” in the human-water system(the water cycle process, the material cycle process, the biological process, and the humanistic process). The basic equations, the coupling and calculation method of the “four processes” are summarized and presented. The framework for constructing a distributed human-water relationship model considering the “four processes” and the construction idea of human-water relationship simulator are proposed. An application case study in the Qinhe River Basin is also provided. The “four processes” in the human-water system are important foundations for characterizing the human-water relationship. The basic equations of the “four processes” are the fundamental equations for studying the human-water relationship discipline. The model constructed by coupling basic equations is an important tool for simulating human-water relationship issues. This study lays the foundation for further improving the human-water relationship discipline and provides ideas for in-depth research on the human-water relationship model.

Abstract:To support the decision-making and forecasting work for the catastrophic flood in the Haihe River Basin, the Zijingguan and Manshuihe sub-basins, located in the Daqing River where a catastrophic flood occurred in July 2023, were selected for the flood simulation and prediction with the Xin’anjiang-Haihe model based on measured rainfall and discharge data. For the Zijingguan sub-basin, 5 floods from 1996 to 2020 were chosen for the parameter calibration, while for the Manshuihe sub-basin, 8 floods from 1953 to 2016 were used. The simulation was validated against the Haihe “23·7” basin-wide extreme flood event. The results showed that the relative errors of peak discharge and flood volume in both sub-basins were within 20%, with a peak timing error of 0 hours. The high accuracy of the hydrological model constructed in this study, along with the good agreement between simulation and measured results, demonstrates its ability to reflect the actual flood process. A comparison between different models revealed that the Xin’anjiang-Haihe model performed better in the Manshuihe sub-basin, which is more affected by human activities, compared to the Zijingguan sub-basin with lesser human influence.

Abstract:In order to address the problem of directly discharging of untreated sewage from storm pipes causing a range of water pollution problems and the uncertainty problem of source inference due to the complexity of drainage system conditions, the storm water management model (SWMM) was employed to simulate the variation of water quality within the drainage system. A SWMM-Bayesian traceability model based on the Bayesian-MCMC (Monte Carlo Markov Chain) method was constructed using the MatSWMM toolbox to predict the probability distributions of the location of each potential source, the extent of discharge, and the time of discharge. Example validation results show that in the case of reasoning about a single unknown parameter of a single pollution source, the SWMM-Bayesian traceability model can accurately determine the true value of the unknown parameter. When all three parameters of a single pollution source are unknown, due to the existence of a variety of combinatorial properties, the traceability accuracy will be reduced significantly, and can only be judged to be in the approximate range, but it can be increased by adding the appropriate water quality monitoring points, to improve the accuracy and efficiency of SWMM-Bayesian traceability model. For the case that the maximum number of pollution sources is 2, the SWMM-Bayesian traceability model is easy to be trapped in the local optimal solution, and the improvement of the traceability model by using the likelihood function to optimize the initial value of the iterative process can effectively solve the problem of local optimal solution.

Abstract:By selecting the fish habitats at the main stream of Dadu River 13.km below the dam of a hydropower station and in the upper tributary reaches 4.km above the confluence of Dadu River and tributary as studying objects, the habitat suitability evaluation was carried out from two aspects: the calculation of effective habitat area for fish and the simulation of river bottom connectivity of the tributary. The suitability indexes of two target fish, Schizothorax prenanti and Schizostomus distomus, in spawning period were analyzed and evaluated to obtain the suitability index of fish habitat suitability index and grade of fish habitat suitability index in the study reach. The habitat suitability index of fish in the main stream below the dam was 0.68, and the suitability grade was suitable. The habitat suitability index of fish in the 4.km river above the mouth of the tributary is 0.58, and the suitability grade is generally suitable.

Abstract:Based on the physical model test, this paper studies the variation characteristics of hydrodynamic pressure, holding force and slip-stick vibration response of a plane gate during the transient closing of the gate, and discusses the influence of vertical hydrodynamic pressure and the friction factor of the gate support on the slip-stick vibration. The results show that the amplitude and period of slip-stick vibration increase gradually with the opening of the gate, and the vibration dominant frequency decreases, which is consistent with the natural frequency of the simplified system. There is a significant difference in intensity and frequency domain between the vertical hydrodynamic pressure and the slip-stick vibration, and the flow pulsation factor is not the main factor causing the slip-stick vibration. The friction characteristics of gate support is the main factor causing the slip-stick vibration, proving the rationality of the simplification of friction in theoretical model.

Abstract:In order to solve the problem that most of the current construction plan optimization methods ignore the impact of the randomness of the construction progress indicators of each key node on the construction plan optimization, and at the same time, it is difficult for the attribute weight determination method to achieve the overall optimization of high-dimensional and multi-level characteristic problems. This paper proposes a stochastic and intelligent optimization method for time-series multi-attribute construction schemes of high arch dams based on the prospect theory (PT) and the sparrow search algorithm (SSA). According to the construction characteristics of high arch dams, a time-series multi-attribute stochastic intelligent optimization model is established based on PT, and a dynamic reference point setting method is built based on the stage development characteristics. The optimal attribute weight and stage weight search model is established based on SSA, and the fitness function is constructed with the idea of maximizing differences to realize the model solving. The results of engineering application show that the proposed method is consistent with the optimization results of the prospect stochastic dominance-CRITIC method (PT-CRITIC) and the stochastic dominance method, and the proposed method has more advantages in scheme discrimination than the other two methods.

Abstract:Based on the Particle Swarm Optimization (PSO) and Least Square Support Vector Machine (LSSVM), a nonlinear mapping relationship is constructed. Combined with the Back Propagation Neural Network (BP) for machine learning on the database generated by the nonlinear mapping relationship, the PSO-LSSVM-BP model is built to determine the optimal mechanical parameters of rock mass. The PSO-LSSVM-BP model takes the monitored displacement data of high slope as input information, obtains the mechanical parameters of high slope rock mass through the inverse analysis, and applies them in the numerical calculations of displacement with FLAC3D. The results show that the simulation results are in good agreement with the monitoring data, which verifies the feasibility and effectiveness of the model. Utilizing the PSO-LSSVM-BP model, a three-dimensional stability evaluation is established on the intake slope of the Lianghekou Hydropower Station at different reservoir water levels. The results indicate that water level is the primary factor affecting the slope stability. As the water level rises, slope displacement gradually increases, with surface and fault damage increasing. While safety coefficients of local point decrease, the overall point safety coefficients remain above 1.30, indicating the intake slope has a certain level of safety margin.

Abstract:In order to explore the influence of hydraulic gradient on the seepage erosion in soil, fused silica sand was used as the transparent soil material, and the pore solution was configured with No.15 white oil and n-dodecane in a certain proportion.Based on the seepage erosion system developed by PIV-PLIF(particle image velocimetry and planar laser induced fluorescence), the influence of hydraulic gradient on the flow velocity distribution of pore solutions and the movement of fine particles in seepage erosion damage was explored. The results show that with the increase of the hydraulic gradient, the flow velocity of tracer particles also increases and the irregular motion phenomenon intensifies, and the flow velocity tends to be stable until the sample fails. Under the same hydraulic gradient, the macroscopic flow velocity is slightly larger than the microscopic flow velocity, and the gap between the two is also narrowing with the increase of the hydraulic gradient. When the hydraulic gradient reaches the critical hydraulic gradient, the fine particles in the particle skeleton begin to lose, and the permeability coefficient also begins to change.If the water head continues to increase, a large number of fine particles will be lost, resulting in the continuous development and expansion of the seepage channel, and finally the critical hydraulic gradient of failure will be reached.

Abstract:In order to study the operational safety of large box floating structures during sea transportation, a physical experiment of hydrodynamic response of floating structures during reverse towing under normal operating conditions was carried out. From perspective of the evolution law of motion spectrum, the six-degree-of-freedom movement of floating structures under irregular wave action was regarded as the studying object. The motion response of the floating structure under the change of significant wave height, mean wave period and towing speed was discussed. The results show that pitch and heave yield a stationary response to the irregular wave load, and are sensitive to average wave period and towing speed. With the increase of the mean wave period, the motion spectra of the pitch and heave transition from multi-peak spectrum to single-peak spectrum, with the shape of the spectrum turning regular and narrowing gradually. In addition, the peak frequency is close to that of the wave spectrum, and the relative peak frequencyis close to 1 and increases with the increased mean wave period. With the increase of towing speed, the shape of heave motion spectrum is gradually sharp and steep, and the relative spectral peak as well as the spectrum peak density grows, indicating intensified hydrodynamic response. Last, the maximum possible heave distance and the maximum possible pitch angle increase with the enhanced wave height, and the maximum possible pitch angle decreases with raised towing speed.

Abstract:In this study, a numerical flume model is established based on the viscous fluid theory and the finite volume method using OpenFOAM, one open-source computing platform, to systematically verify the accuracy and precision of calculation of strong nonlinear wave propagation and wave propagation deformation on submerged embankment topography. The influence law of incident wave amplitude and the slope of submerged breakwater on the wave propagation characteristics is explored. The results show that the numerical flume model accurately simulates the strong nonlinear wave propagation, and the wave surface changes as the wave is spreading through the submerged breakwater. In the case of small wave steepness, the surface wave shape exhibits a good periodicity, and there are phase differences between different slopes, which indicate that if the slope is flatter, the phase is more lagged. In the case of large wave steepness, the wave shapes of different slopes show strongly nonlinear and there are great differences in surface wave shapes due to wave breaking. As wave steepness increases from 0.53% to 3.00%, the mean value of the dimensionless peak-to-valley difference of the wave surface decreases, which indicate that a gradual enhancement of the reflection effect of the submerged breakwater as the wave steepness increases.

Abstract:To accurately assessing the demand response potential of meteorologically sensitive loads in the power grid, an assessment method for the demand response potential of meteorologically sensitive load is proposed based on the fusion of mechanism-data hybrid driven methods. At first, the meteorologically sensitive load power at the grid level is estimated based on a data-driven two-branch neural network model. Secondly, based on the equivalent thermal parameters model, a physical aggregation model of meteorological sensitive loads is established. With the goal of minimizing the error between the aggregate power and the estimated power, the control variable method and the particle swarm optimization (PSO) algorithm are used to optimize the equivalent parameters of the physical aggregation model, including the number of temperature control load devices and the temperature setting values. Finally, the user’s comfort and willingness are considered to evaluate the demand response potential of meteorologically sensitive loads. The case analysis shows that the meteorologically sensitive load power estimated by the proposed method has a significant correlation with temperature, and the obtained equivalent parameters of the physical model and demand response potential are consistent and reasonable with the actual situation.

Abstract:In order to solve voltage fluctuation and off-limit problems caused by the large-scale grid connection of new energy stations such as wind power and photovoltaic, as well as the problem of traditional reactive power and voltage calculation methods easily falling into local optima, a new optimization model based on improved firefly algorithm (IFA) for the regional power grid is proposed. In this model, the sum of standardized active power losses, node voltage deviations, and reactive output deviations is used as the optimization objective. Meanwhile, regional power flow calculation, terminal voltage and reactive capacity of thermal power units, transformer ratios, active power of new energy stations and reactive power of static var compensators are used as constraints that needs to be met. Then, by using an IFA to solve the optimization model, the algorithm’s computational accuracy and global optimization ability are increased by introducing new step size and position update formulas. Finally, the effectiveness of the presented model is validated using an IEEE-30 bus system. The results indicate that the proposed optimization model can reduce the active power loss of the system, improve the reactive power distribution of the regional power grid, resist the voltage fluctuation of the system, and improve the power quality of the regional power grid. IFA can effectively improve the calculation accuracy and speed, and improve the global optimization ability.