جستجوی مقالات مرتبط با کلیدواژه "open channels" در نشریات گروه "کشاورزی"

Open channels have an important role in transferring water and flood control. Of course, it imposes the high cost to water supply projects. In the present study for the first time, bat algorithm has been usedfor optimal channel design. For this purpose, five different models are considered. In the first model, trapezoidal channel and manning equation are used. The second model is such as the first model, but the trapezoidal cross-section of the channel divided into two triangular segments and one rectangular segment. In the thired one, the maximum velocity is considered as a constraint. The fourth model is such as the second model, but the permissible side slope is considered as a constraint. The fifth model resembled the first model, but Froude number is considered as a constraint. In modeling, the cost of channel construction is considered as an objective function. Optimal parameters of bat algorithm are selected by using thesensitivity analysis. The coefficient of variation of ten random runs for different models is about 0.00001 to 0.00017. The results of proposed algorithm have been compared with LINGO software solutions and several common intelligent algorithms. Based on the findings, the results of bat algorithm significantly are close to the global solutions of LINGO software. The accuracy of this algorithm is also more than the other evolutionary algorithms. According to the other results, using the bat algorithm for the different evolutionary methods hascausedto 32% decreasing in cost. Among five considered models, the second model has the lowest cost. Used second model instead the first model is lead to 47% decreasing in cost. But, adding maximum velocity, permissible side slope and Froud number constraints to the second model has caused to 65%, 39%, and 55% increase in cost. Also, the proposed algorithm converges in 100to 500 iterations.

Prediction of flow distribution is necessary in open channels junctions at irrigation and conveyance water systems in order to design suitable plans and protect them in emergency situations. In this study, a one dimensional analytical model of subcritical flow distribution using mass - energy and momentum conservation laws was presented for a four-branch junction of open channels and compared with experimental results. The results showed that as the inlet discharge ratio and bed elevation of the lateral channels increased, the outlet discharge of the main channel increased. Furthermore, as the Froud number at the inlet of the main channel decreased, the outlet discharge of it increased. Changes in the height of the weirs at the end of the outlet channels had no considerable effect on the flow distribution. The maximum and minimum deviations of the flow amounts to the outlet lateral channel occurred at the angles of 60 and 90 degrees, respectively. Comparison of the analytical and experimental results showed a good agreement between them so that the maximum error was less than 10%.

Artificial open channel structures are expensive infrastructures in terms of their materials, construction and maintenance. Design of a minimum cost channel section involves minimization of the sum of costs per unit length of the channel, subject to uniform flow condition in the channel. In this research, the objective function was expressed using the cost per unit length of the channel for lining, the depth-dependent unit volume earthwork cost, and the cost of water lost due to seepage and evaporation. A general resistance equation was used as an equality constraint. Optimal design of trapezoidal channel sections using genetic algorithm with depth, bottom width and side slope variables was accomplished. Two methods and several Models were evaluated including no restriction and restriction on normal depth, velocity of flow, side slope and top width. Restricted depth, velocity and side slope resulted in higher costs. However restricted top width resulted in lower costs comparing with other models. Also, another model was employeed which used the Manning equation as an equality constraint.