Abstract:To explore the realization method and applicability of the flood probability forecast under the comprehensive influence of various uncertain factors, the study was carried out in Shiguanhe River Basin from 2003 to 2020, on the premise of quantifying the input of rainfall, model parameters and uncertainty degree of structure. The probabilistic flood forecasting is realized by fusing the uncertainty of every source based on the MCMC method, while the reliability and accuracy of the prediction results are evaluated based on the coverage ratio and the certainty coefficient, respectively. The results show that synthesizing the 5% to 95% confidence interval of the probabilistic flood forecasting method can predict the flood development process in a stable envelope and reduce the possibility of false alarm and missing alarm effectively. The result of mean value forecast is better than that of original single model forecast, which improves the reliability and reference value of flood forecast.

Abstract:To investigate the solutions to the problems of severe groundwater over-extraction and mixed and variable runoff generation mechanisms(alternating dominance of the saturation-excess and infiltration-excess runoff generation with time and space)in North China, based on the distributed TOKASIDE model, a distributed spatial dynamic combination hydrological model(TOKASIDE-D)was established by dynamically identifying the saturation-excess and infiltration-excess runoff generation grids through the relationship determination between precipitation and soil water content. The Beixindian Watershed in North China is selected for the validation and the analysis. The results show that compared with the original model, the flood simulation accuracy of TOKASIDE-D model in the Beixindian Watershed is improved significantly, the qualified rate of runoff depth error is increased from 44% to 56%, and the qualified rate of flood peak error is increased from 44% to 78%. TOKASIDE-D model can accurately capture the control effect of rainfall, soil moisture and other dynamic factors on the runoff generation mode.

Abstract:To further explore the usefulness of bioelectrochemical systems(BES)in promoting the municipal wastewater treatment, the influence and mechanism of the emerging pollutant dibutyl phthalate(DBP)on electroactive biofilms(EABs)were investigated. Using the electrochemical workstation, scanning electron microscope, confocal laser scanning microscope, high-throughput sequencing, and other methods, this study analyzed the effect of DBP concentration on the electrochemical activity, main components, microscopic morphology, spatial structure, and microbial community structure of EAB. The results showed that under the condition of high concentration DBP(10 mg/L), the maximum output voltage and power density of BES were 0. 24 V and 113. 34 mW/m², respectively, which were 33. 33% and 31. 47% lower than those under a low concentration DBP(1 mg/L). The measurement results of protein and polysaccharide in biofilms indicated that high concentrations of DBP stimulated the secretion of β-polysaccharide and showed a strong blue signal on the laser confocal image, while the contents of protein and α-polysaccharide did not change significantly. In addition, the microbial community analysis of EAB under different concentration DBP showed that Petrimonas and Aquamicrobium were the dominant genera under high concentration of DBP. This research also showed that DBP will inactive the electrochemical performance of EAB, and Petrimonas and Aquamicrobium play an important role in the process of biofilm against DBP toxicity.

Abstract:Based on the sea surface temperature(SST)indices in previous winters, a Generalized additive model(GAM)model was constructed with four non-linear and nine linear indices, to simulate and forecast the summer runoff of Hongjiadu hydropower station on the Wujiang Basin. Five evaluation indices were used to evaluate the simulation results of GAM and Generalized linear model(GLM), including the Akaike information criterion(AIC), the root mean square error(RMSE), the mean absolute error(MAE), the linear error in probability space(LEPS)and the linear correlation r. The results showed that the ratios of simulated data to real data by GAM were smaller than those by GLM in AIC, RMSE and LEPS, while the linear correlation coefficient of GAM was obviously larger than that of GLM, thus GAM performed better than GLM. Leave-one-out Cross validation was used to forecast the summer runoff of Hongjiadu hydropower station with GAM and GLM, respectively. The forecast results indicated that the correlation coefficient between the GAM result and observed data was improved to 0. 41 and predicated data with relative error less than 30% was more than 60%. The prediction error of GAM was around 10% in the typical flood year of Hongjiadu and less than 10% in the typical dry year. It can be concluded that the prediction accuracy was improved in GAM compared with that in GLM. Consequently, considering the the non-linear relationship between runoff and prediction factors, the use of GAM in runoff forecasting can effectively improve the simulation result and prediction accuracy than the linear regression model.

Abstract:A heterotrophic nitrification and aerobic denitrification strain L3 was separated and identified from bioflocs in the aquacultural system, to investigate the influential factors of bacterial growth and the denitrification performance. The result of 16S rRNA gene sequence analysis showed that the strain L3 was Pseudomonas. The optimum pH for the growth of strain L3 was 6 to 8, the suitable carbon source was sodium succinate, and the optimum temperature was 25-35℃, with the optimum C/N from 10 to 15. The strain L3 could tolerate the high ammonia concentration. By studying the characteristics of heterotrophic nitrification and aerobic denitrification, the strain L3 was found to preferentially remove ammonia and had good aerobic denitrification performance.

Abstract:Aiming at the problems that a large amount of slag sludge is difficult to be treated in the excavation of urban pipe network and the backfilling of the basement is lacking in good quality backfilling, the technology of improving the slag sludge to the flowable fill for in-situ use is studied and applied in a demonstration project. Measurements of the fluidity and the strength by indoor experiments indicates that the fluidity increases significantly with the increase of water consumption, and the strength increases with the increase of the amount of solidified material and the age of curing. The water-solid ratio and the lime-sand ratio can be used as the ratio index parameters of the fluidized backfill. When the water-solid ratio is 0. 63 and the lime-sand ratio is 0. 15, the flowable fill has a fluidity value of 242 mm, and it has the early-strength performance, which can reach 98 kPa in one day and 390 kPa in 28 days, meeting the design of fluidized backfill. This paper discusses the application and effect of this technology in engineering in combination with the pipe network embedding project in the management of Maozhou River in Dongguan. Through the on-site construction and the follow-up inspection, it shows that the slag excavated on site is mixed with the above ratio, the flow value is between 188-218 mm, and the strength at 28 d is between 324-362 kPa, fully meeting the requirements of pipe network backfill.

Abstract:A revised moment-rotation relationship of friction damped self-centering connection was improved and the design idea of friction damped self-centering connection was put forward to meet the design targets of different seismic performance of modern building structures. The finite element software ABAQUS was used to design 5 specimens of composite frame with friction damped self-centering connection and simulate their seismic performance under cyclic loading. Based on the simulation data, the axial compression, the dimension of the slotted hole, the boundary condition at PEC column bottom and the bolt layout of T-stub were taken into consideration to obtain influence mechanisms of these factors on the seismic performance of specimens, including the hysteresis performance, lateral stiffness degradation, residual deformation, and energy dissipation capacity. The results demonstrate that the bearing capacity and lateral stiffness of PEC column meet the requirements of the vertical members for the self-centering structures and the dimension of the slotted hole can be flexibly designed to control the developing process of friction slip energy dissipation and bearing-type force-transferring mode, to meet different seismic performance design targets. Meanwhile, the layout of high strength penetrating bolts in practice can soundly play the self-centering function and friction energy dissipation capacity of partial self-centering connection. The connection type of the PEC column bottom has meaningful effect on the loading-deformation and the stiffness distribution of the frame, while the second-order effect of the axial compression just has adverse impact on the self-centering function and bearing capacity.

Abstract:The panel data model accounts for the relationships and the heterogeneities among points, therefore, it was introduced in this study to construct a zoned safety monitoring model for super high arch dams. Firstly, the principal component analysis(PCA)was used to select the typical variables of measured temperatures. Secondly, the hierarchical clustering method based on PCA was applied to propose a data-based zoning method for deformation monitoring points. Then the panel data of each zone was established, and its type was determined by statistical tests, thus the corresponding regression model zone was constructed. Finally, through the comparative analyses of the spatial distribution of zones and the fitted parameters(e. g. , intercept terms and variable coefficients of various zones), both the deformation characteristics of zones and the spatial deformation characteristics of the dam can be identified. A super high arch dam during its initial operation period was investigated, and the focused plumb line points were divided into four zones according to the observation data. After the statistical tests, fixed effect regression models of zones were established. The results show that the spatial deformation is in accordance with the actual condition, and the factors such as the unstable temperature field and the nonlinear time varying effect during the initial operation period have obvious influences on the dam deformation.

Abstract:To comprehensively consider the influence of activity time randomness, machinery failure, collapse, water inflow and other risks on the construction scheme optimization of a diversion tunnel, and realize a reasonable selection of the construction scheme, the construction scheme optimization method of diversion tunnel is proposed considering the influence of risk factors. To begin with, the optimization model of construction scheme considering risk factors is established. In addition, an Levy flight adaptive chaos particle swarm optimization(LFACPSO)algorithm is proposed to solve the model for obtaining the Pareto scheme set. In this algorithm, the Levy flight is adopted to improve particles’ ability of jumping out of the local optimum, then the chaos algorithm is used to initialize particles, and the inertia weight coefficient is adjusted adaptively. Finally, the IFEWPA method is used to select the final scheme considering the experts’ hesitation degree from alternative scheme set. The application shows that, compared with construction scheme simulation schedule neglecting risk factors and planned schedule, the simulation schedule considering risk factors is closer to the actual schedule, which proves the effectiveness of the construction scheme optimization method considering risk factors. Furthermore, LFACPSO algorithm is compared with ACPSO, PSO and NSGA-Ⅱ algorithms, and the results prove the superiority and robustness of LFACPSO algorithm, with the maximum mean value and the minimum standard deviation.

Abstract:Aiming at problems of the index weighting and the operator optimization of fuzzy comprehensive evaluation(FCE)method in the aqueduct safety evaluation, a comprehensive evaluation method of aqueduct safety based on the of improved FCE method was proposed. In the proposed method, the analytic hierarchy process(AHP)method based on the natural index of e^0/5 to e^8/5 was used to obtain the subjective weight of each evaluation index, and the objective weight of the experts was calculated by entropy weight method to optimize the subjective weight. Then the total objective membership degree was calculated by introducing the all-optimal synthesis operator, and the risk degree was obtained by the weighted synthesis with the corresponding risk grade, to determine the safety category of the aqueduct. The method was applied to the safety evaluation of a specific project, and the results show that the evaluation results were consistent with those of the principal factor protruding type composition operator and the weighted average type composition operator. This method reduces the subjective deviation, avoids the selection of operators, and has strong maneuverability.

Abstract:A long-distance and large-flow water conveyance project is selected as a study case, and effects of the diameter of impedance hole on the water hammer protection and the minimum surge are systematically analyzed under two layouts, which are single throttled surge chamber and series throttled surge chambers. The results show that for the single throttled surge chamber scheme, through changing the diameter of the impedance hole of the surge chamber, the water hammer pressure can be reduced, the minimum surge in the surge chamber can be increased, and the surge chamber area can be effectively reduced. Compared with the single surge chamber scheme, the effect of the series throttled surge chambers is better, for it can increase the minimum pressure along the pipeline and the minimum surge, significantly reduce the total area of the surge chambers, and all the surge chambers have optimal impedance apertures.

Abstract:To study the complex hydraulic characteristics of the surge chamber with partition-type bifurcation pipe in bottom, a three-dimensional numerical model is built to analyze the local water flow patterns under typical flow regimes, the relationship of local head loss coefficient and split ratio under split/combined flow state, the head loss coefficient of flow through the bottom of surge chamber under normal operation state and the head loss characteristics. Moreover, a conversion formula is derived between the head loss coefficient and the flow coefficient when all water flows into/out of the surge chamber. Based on the analysis, the local hydraulic characteristics of surge chamber with partition-type bifurcated pipe in bottom are completely clarified. The results show that, the numerical simulation method can accurately reveal the hydraulic characteristics of the given surge chamber and the computed flow coefficient flowing into/out of the surge chamber is mostly between 0. 6 and 0. 8, which is relatively larger than the code.

Abstract:To solve the lack problems of overall planning and information management of precast concrete components stacking in prefabricated construction site, a mathematical model for the packing optimization was established based on the analysis of the site stacking scheme and the hoisting distance of precast concrete components. The solving method for the model was proposed based on the genetic algorithm and the surplus rectangle algorithm, and a packing optimization system was developed. The packing optimization system could be used for both the stackable condition and the non-stackable condition by providing the optimum scheme including the stacking position and the stacking order with the minimum hoisting distance. Moreover, the management process of precast components is clear, and managers can arrange the precast packing according to the optimum scheme. A case study demonstrates that the optimization system improves the management level and hoists the efficiency of precast. Meanwhile, it can reduce the reliance on the site management experience and realize the information management of precast.

Abstract:To solve the problems that the PV array cleaning robot is easy to be affected by the frame between modules and the smooth surface of modules, the path tracking control of the PV array cleaning robot based on the improved navigation round algorithm is proposed for avoiding the offset from the original track. Firstly, the kinematics model and ultra-wide band positioning system of PV array cleaning robot are given in this study. Through the simulation of the original algorithm, the long adjustment distance of the robot is found and analyzed. Then an improved navigation round path tracking algorithm is proposed, which revises the correction angle of the original algorithm and readjust the correction angle until the robot returns to the target path. The experimental results show that, compared with the original algorithm, the adjusted distance is reduced by more than 50%, thus the new algorithm improves the adjustment efficiency.