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A biological particle model is used to predict the upward trajectory of fish under a dam, the biological particle model refers to a fish as a particle and considers the flow rate, velocity gradient and turbulent energy of the fish, as a condition of retrospective behaviour, a control equation is used to simplify the fish's retroactive behaviour and establish a model programmed in MATLAB to develop a fish traceability prediction program. According to the program, the upward trajectory of the fish under the dam is predicted, there are three types of up-tracking channels under the dam according to the average widths of the up-tracking channels along the right bank of the channel, along the middle of the channel, and along the left bank of the channel and the average widths are 10, 14 and 7 m, respectively. The three existing fish import locations in fishway project are evaluated, and optimization recommendations are provided, it's recommended to add a fishway inlet along the right bank of upstream channel. In addition, this paper provides a feasible technical methodology that a biological particle model can be used to predict the upward trajectory of fish in similar fishway projects.

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The precision machining of hard and brittle materials has always been a research frontier and difficult problem in the industry. In this paper, it is verified theoretically and experimentally that 46.9nm soft X-ray laser can produce regular microcrack arrays on the surface of hard and brittle materials. Taking BaF2 and SiO2 materials as examples, based on the multiphysical field coupling numerical simulation method, the evolution process of temperature and stress, as well as the results of maximum stress section and strain are obtained, which can be used to predict the damage of hard and brittle materials processed by laser thermal cracking. The simulation results show that the maximum stress and strain of BaF2 have exceeded the strength limit, while the maximum stress and strain of SiO2 are less than the strength limit. The experiment shows the same result, that is, BaF2 has fracture failure while SiO2 has no fracture failure. The simulation and experimental results are the same, showing that the 46.9nm soft X-ray laser can be used for precision thermal cracking of hard and brittle materials.