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The main theories of spatial autoregressive model and model selection were used to study the spatial correlation between suspended sediment, sea surface temperature and alga during summer 2011 in Changjiang estuary. The results indicated that: there were significant high spatial autocorrelations in the spatial distributions of suspended sediment, sea surface temperature and alga, respectively; Suspended sediment always had significant and positive spatial correlation effect on the distribution of alga, Sea surface temperature had significant and positive spatial correlation effect on the spatial distribution of alga in June and August, but this effect decreased in July; The spatial distributions of suspended sediment and alga were closely correlated. Suspended sediment was the key dominant factor of the growth and bloom of alga, also the source of nutriment of alga.

This paper aimed to research the effects of inertial mass coefficient on knotless netting models used in tuna purse seine. Knotless nettings were modeled and simulated using mathematical and mechanical models. In the simulation, the marine environment was imitated in the computer. The results demonstrated that inertial mass coefficient was a key factor to affect the stability of knotless model, especially in the sinking process, and the model presented more stable and quicker convergent as the inertial mass coefficient increased. During fishing operation at sea, the instability of the sinking of purse seine with knotless nettings, especially in the area with complicated currents and waves, might be due to the smaller inertial mass coefficient of knotless nettings.

Based on finite element analysis and explicit Euler method, the present study visualized the dynamical simulation of a knotless netting in R environment. In the physical models, the linking between knot and twine were considered as a mass-spring system. Vector algebra methods were applied to analyze the hydrodynamic forces and tensile forces of the spring. To solve the equations numerically, explicit Euler method was introduced for the mechanical system to achieve the stable solutions. A package of scatterplot3d in R program was transferred to realize the visualization of the knotless netting in three-dimensional space. The results of dynamical simulation were displayed distinctly to show the sinking processes and equibibrium state of the knotless netting in the sea water.