He Kunjin

Simulation of dredging processes of a cutter suction dredger

Dredging simulation is of great significance to the development of dredging engineering technology of harbor, waterway, rivers, lakes, etc. The design and implement of the dredging simulation system are introduced. The modeling and key techniques for the virtual reality of construction site, the movement of dredge vessel, the soil cutting of cutter, and the hydraulic transport of sand in a pipeline, etc., are discussed. The cutter suction dredger simulator with a multi-channel round screen has been put into operation and produced good results.

A representation of freeform features based on characteristic curves

Owing to the diversity and complexity of freeform surface shapes, it is difficult to parameterize surface features and express their shapes effectively. A parametric approach for layering freeform surface features is proposed based on characteristic curves. A characteristic curve is a key element and is regarded as the basic unit for building surface shapes. A characteristic curve can be divided into four levels, comprising, from the lowest to the highest level, geometry, constraints, grammar, and semantics. The information is used to layer the parameters of a freeform surface feature so that the global and local shapes of the surface feature can easily be manipulated by the layered parameters. The global shape is controlled by the high parameters between multi characteristic curves, while the local shape is manipulated by these parameters with a single curve. According to the degrees of the surface and its parametric representation, freeform surface features can be divided into two types: semi-freeform and fully freeform. Then, the freeform surface feature is combined in the representation. Using various examples we show that the proposed method can fully express complex surfaces and is effective in defining freeform surface features, making it convenient for designers to edit freeform features from higher-level semantic parameters. Moreover, it provides an efficient way of representing freeform surface features.