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Teng K.,Qiqihar Municipal Water Affairs Bureau
Advances in Science and Technology of Water Resources | Year: 2013

The calculation of critical depth of the open channel with a standard U-shaped cross-section is difficult because of its complicated formula. In order to solve this problem, a simplified formula of the critical depth was derived by using the optimized fitting method and taking minimal standard residual difference as an objective function. The simplified formula meets the engineering requirement, and its calculation has the advantages of simple, fast, and high accuracy. Source


Teng K.,Qiqihar Municipal Water Affairs Bureau
Advances in Science and Technology of Water Resources | Year: 2014

Egg-shaped cross-sections are complex in form, calculating such water surface profiles with conventional methods has the disadvantages of error accumulation, a large amount of necessary calculation, and low efficiency. To improve the calculation, the optimum matching theory was adopted in this study. An objective function of minimized standard residual deviation was selected, and a simplified general formula was obtained by the fitting calculation, which could be used to substitute for the segmented and non-integrable function in the original integral within the parameter range applicable to projects. Finally, a simplified formula was deduced for calculation of water surface profiles of tunnels with egg-shaped cross-sections. Error analysis and case study show that the calculation error of this calculation is less than 2%. The approximate formula greatly simplifies the water surface profile calculation of tunnels with egg-shaped cross-sections, and the working efficiency is obviously improved. Source


Teng K.,Qiqihar Municipal Water Affairs Bureau
Advances in Science and Technology of Water Resources | Year: 2014

Conventional methods used to calculate water depth in parabolic-shaped channel with contracted section have the drawbacks of heavy computational effort and low accuracy. Additionally, the exiting simplified formulas can only be used in specific parabolic-shaped sections and are not simple enough to calculate the water depth. In order to solve these problems, the basic formula of water depth was modified by introducing the comprehensive parameters and dimensionless relative water depth. The simplified general formula was proposed by fitting a polynomial of higher degree while meeting the precision demand of engineering design. Computational results and precision analysis show that the maximum relative error of the general formula is only 0.755%, which meets the precision demand of engineering design. Thus, the simplified general formula proposed here can be used in real practical applications. Source


Zhang L.,River Management Office of Qiqihar City | Teng K.,Qiqihar Municipal Water Affairs Bureau
Advances in Science and Technology of Water Resources | Year: 2014

A relatively systematic study on the optimum hydraulic parameter of parabolic transaction and the calculation of parabolic optimum index have been studied in this paper. Through sorting out the variants and calculating the approximate integration of the equation of uniform flow for such transaction, this essay presents the simplified formula for the optimum hydraulic parameter of the open-channel water-flowing transaction in case of a given parabolic equation index. By analyzing the simplified equation, we found a new optimum equation index of parabolic transaction to be 3.35 on the condition that other parameters of the open-channel such as water flow, gradient and roughness stay unchanged. Our finds also show that the presentation of the optimum hydraulic parameter serves as the basis for the further optimization design of parabolic transaction. Additionally, through the comparison of the optimum index of parabolic transaction and other hydraulic optimum transactions, the optimum index of parabolic transaction shows a higher economic indicator and therefore, it is worth extending the application. Source


Teng K.,Qiqihar Municipal Water Affairs Bureau
Advances in Science and Technology of Water Resources | Year: 2013

A transcendental equation which has a complex expression form needs to be solved in three sub-sections in order to calculate the critical depth of an egg-shaped cross section. The equation can not be solved directly by an analytical method and the conventional trial method has the drawbacks of heavy computational effort, low efficiency and inconvenience for practical applications. Based on the optimal fitting theory, an objective function was chosen for the smallest standard residual difference. By fitting computation confined to suitable parameters in engineering, a general approximation formula was proposed. The formula has a simple expression, no sub-sections for calculation, easy for practical application. Precision analysis and computational results show that the maximum fitting error is only 0.649% and the process for critical depth calculation of an egg-shaped cross section can be greatly simplified, and the working efficiency can be improved significantly. Source

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