Finite difference method–based calculation of gravity deformation curve for the large-span beam of heavy-duty vertical lathe

To solve the problem that gravity deformation curve of large-span cast-iron beam analyzed by finite element method simulation is inaccurate due to material imperfection, a discretization calculation considering the inhomogeneity of the material based on finite difference method is proposed. Supposing the flexural rigidity of the beam is different along the length, the continuous beam is discretized into segments based on finite difference method, and equivalent flexural rigidity is presented to characterize the inhomogeneity of the material. Correction model of bending deformation is constructed to revise the results of finite element method simulation applying equivalent flexural rigidity that could be obtained by combining the discretization model and deformation data acquired in a simple self-load experiment in which the beam is simply supported without any assembly process. Finally, flowchart of application is presented, and the approach is illustrated through an example from real case. The experimental results show that the computational accuracy is improved from 73.14% to 88.33%, compared with just finite element method simulation

The Impacts of Molybdenum Exploration on Cd and Zn Contents in Surface Water: Evidence from a Molybdenum Mine in the Xiaoqinling Mountains

In order to study the impact of molybdenum ore development in a large molybdenum mining area in the Xiaoqinling Mountains on the water and sediment quality of the Wenyu stream, surface water, sediment, and surrounding rock samples were collected, and the Cd and Zn contents were analyzed. The pollution status and ecological risk degree of river water and sediment samples in the Wenyu stream watershed were evaluated using the single element pollution index method, geoaccumulation index method, Hakanson potential ecological risk assessment method, potentially toxic elements (PTEs) health risk assessment, and PTEs pollution comprehensive index method. Finally, the impact of mining development on the contents of Cd and Zn in the Wenyu stream were discussed, and the sources of pollution were identified. The study revealed that the levels of Cd and Zn in 23 water samples collected from the primary channel of the Wenyu stream were markedly higher compared to the unaffected contrast area. Similarly, the concentrations of Cd and Zn in the 17 sediment samples were significantly elevated compared to the average values in the reference area. These findings indicated that The Wenyu stream was heavily impacted by the molybdenum mining activities, resulting in a high ecological risk associated with the sediment in the primary channel. Acid mine drainage in the mining area, sediment release activities, and atmospheric dust fall are considered to be the main sources of PTEs polluting the Wenyu stream watershed. Relevant personnel should complete a thorough river water quality investigation and perform ecological environment restoration so as to ensure sustainable economic development