Journal of Hydraulic Structures
Volume:8 Issue: 4, Winter 2022

The present research focuses on optimizing the laboratory synthesis of a metal-organic framework for decomposing organophosphorus pollutants in aquatic environments (caused by pesticides). In the first stage, by defining and scoring five screening criteria, such as the price of raw materials, the complexity of the synthesis reaction, the efficiency of the catalyst, the possibility of industrial production (scalability), as well as the cost of the necessary equipment, the metal-organic framework 2-aminoterephthalate;oxygen(2-);zirconium(4+);tetrahydroxide was selected as the target catalyst. By considering the catalyst production yield as an objective function, the optimization of the most important variables affecting catalyst synthesis (reaction time, reaction temperature, amount of reaction solvent, type and amount of acid catalyst required, type and quantity of secondary solvent, and rotation speed of centrifuges) was discussed. The synthetic framework’s structure has been confirmed by infrared spectroscopy and powder X-ray diffraction analyses. According to Brunauer-Emmett-Teller surface area analysis, the resulting catalyst has a specific area of 825 m2/g and a mean pore diameter of 2.25 nm. This catalyst performed well in the laboratory in decomposing the selected organophosphorus pollutant (dimethyl nitrophenyl phosphate compound) with a half-life of 9 minutes.

Today, due to lack of water resources, particularly safe drinking water, countries are experiencing a turmoil resulting in the formation of many crises in them. Hence, Iran is one of the countries all over the world where the water crisis is more pronounced compared to other countries, leading to the formation of security consequences in various parts of the country. Thus, this crisis in the country must be especially taken into account so that an organized space can be witnessed. Accordingly, this study is aimed at investigating and analyzing the water crisis and its security consequences in Iran. Hence, the present study is conducted in a descriptive-analytical format and based on library data. The research results reveal that over the recent decades, the situation of Iranian water resources has reached an alert status, so that it is considered on the verge of entering a water crisis by many experts and some others consider it as a country with a severe water crisis. Accordingly, it is forecasted that with the current situation in Iran, this country will be propelled to a supercritical situation and the conflict will increase over water resources in Iran, in such a way that its consequences will threaten the security of cities and settlements and on the other hand, lead to environmental degradation. On this basis, considering water crisis and resolving it as a major process necessitates the use of elites and presentation of their constructive suggestions to organize the situation of water resources in the country.

Harvesting the river materials can cause negative effects on the river and can intensify scouring around the bridge piers. This study investigates local scouring around roughened pile groups with gravel in the presence of harvesting pits for Froude numbers of 0.1, 0.25 and 0.5. It was found that applying roughness reduced the scour depth by 4.8 cm (73%). Due to increasing pile stability because of reducing local scouring, results show that the application of roughness to the surface of piers is a suitable, straightforward, cost-effective, and easy-to-apply method to reduce scouring. In addition, the maximum scour depth upstream and downstream of the harvesting pit occurred upstream of the initial piers. A comparison of scour areas shows that scour expansion in the transverse direction was greater than in the longitudinal direction and the amount of expansion increases when Froude number has been increased. Also, the extent of scouring around the initial piers was greater than the extent of scouring around the other piers. The maximum scour depth was 15 cm in front of the first pier and corresponded to simple piers and flow with a Froude number of 0.5.

The tanks' useful life will be reduced if their sediments are not discharged with a suitable method. Various hydraulic and mechanical methods can be used in many countries to discharge sediments from reservoirs. Pressure hydraulic sediment flushing is a method of sediment flushing without lowering the water level. In the present study, using the CFD based Flow-3D software, a model has been applied to investigate the pressure hydraulic sediment flushing, and evaluate the effect of blockage phenomenon on sediment flushing efficiency. Results were compared with the available laboratory model. The dimensions of the simulated tank were 2.5 x 1.3 x 1.5 m in length, width and height, respectively, the height of the bed load was 0.4 m, and the diameter of the sediment particles was 0.3 mm according to the laboratory conditions. The average relative error for the sediment flushing cone depth was about 3%. In addition, to investigate the blocking phenomenon, the height of the bed load was considered to be 0.41, 0.45 and 0.5 meters for each simulation. The simulation results showed that when the height of the bed load increases, there is the highest sediment flushing efficiency and more sediment can be removed from the bottom outlet.

As a destructive process, scouring exposes bridge foundations to failure and disastrous consequences. Control structures of various arrangements are capable to change and manage the adverse effects. This paper aims to investigate the effect of submerged vanes of a quasi-triangular arrangement (of heights 0, 4, and 6 cm), eppi, and sills (of height 4.5 and 9 cm) on scour development. All tests were executed in a rectangular slope-less flume covered with sediments of D50=1.8 mm. Temporal and equilibrium scour depth were mapped for Froud numbers: 0.15, 0.2, 0.25, and 0.6. Results clarified the aggregate effect of the eppies on the scour depth due to section contraction. Submerged vanes and sill were set up to deteriorate sediment transport. Although the vane of height 4 cm had the most superior performance, but the sill installation of height 4.5 cm greatly increased vane's effect, so that a remarkable reduction of scour was occurred at the first pier foundation.

Since many years ago, flow measurement has become a fundamental issue in hydraulic engineering. One of the conventional methods of flow measurement is the use of combined structures. In this regard, using a combined structure, including a gate and a weir, is one of the approaches that has attracted the attention of researchers in this field. Therefore, in this research, five different methods based on artificial neural networks were used to predict the discharge coefficient. The networks architecture includes an input layer with four neurons, a hidden layer with seven neurons, and an output layer with one neuron. be mentioned that the number of neurons within the hidden layer is set to 4 only for the recurrent network. For the hidden layer, the logarithmic sigmoid activation function was used. Also, the linear activation function was used for the output layer. Finally, the results showed that the Levenberg-Marquardt (LM) algorithm performs better than the other methods. The convergence speed of this algorithm, which also uses the second derivative, is much higher than others. In this case, the coefficient of determination (R^2) for the training and the test stage was equal to 0.92616 and 0.94079, respectively. In addition to, the first type of rough model with the gradient descent training algorithm also had an acceptable performance and was placed in second place. Also, the sensitivity analysis on the dimensionless parameters affecting this issue showed that the H⁄d, y⁄d, b⁄B, and b⁄d parameters have maximum to minimum effect on the model results, respectively.