大规模地形场景流式渐进传输

着重考察了搅拌器类型以及搅拌转数对氧气动态传质过程的影响.采用计算流体力学(CFD) 对氧气动态传质过程进行了数值模拟,并结合实验以及粒子成像技术（PIV）对模拟结果进行了验证.结果表明，采用Fluent软件并结合用户自定义方程（UDF）能够很好地模拟实际搅拌器内的流场分布.采用氧气传质模型能够预测氧气在搅拌器内的动态传质过程.氧气浓度与溶解时间的对数关系式较好地描述了试验搅拌器内氧气的动态传质过程.在相同搅拌速度下,圆盘涡轮式搅拌器产生的湍流动能分布范围大于浆式搅拌器产生的湍流动能分布范围,而且湍流动能分布更加均匀，湍流强度更大.采用圆盘涡轮式搅拌器有利于增强氧气传质过程.圆盘涡轮式搅拌器比浆式搅拌器的溶解氧浓度高.当搅拌器类型相同时，随着转速的增加，溶解氧浓度增加.

Progressive streaming of massive terrain data

A novel approach of wavelet-based progressive terrain data compression and streaming transmission was proposed,coupled with a new massive terrain data layout,which introduced a remote visualization solution for 3D terrain data over network.The large-area terrain mesh was partitioned into blocks utilizing the regularity of digital elevation mode(DEM) data,then a lifting scheme wavelet was used for the datasets decorrelation of each block.An improved SPIHT algorithm was used for zero-tree wavelet encoding,then the datasets were organized as progressive bitstreams after compression.The resolution of each visible terrain block could be calculated adaptively according to the viewpoint location and the network bandwidth during the interactive rendering.Utilizing the coherences between frames,the bottleneck of massive data remote transmission was solved effectively.