This paper describes a new method for simulation of the cross section shape of log. The self-developed MQK3102 log shape recognizing machine was used to acquire the finite discrete sampling points on the cross section...This paper describes a new method for simulation of the cross section shape of log. The self-developed MQK3102 log shape recognizing machine was used to acquire the finite discrete sampling points on the cross section of log and those points were fitted with the quadratic B-spline parametric curve. This method can clearly stimulate the real shape of the log cross section and is characterized by limited sampling points and high speed computing. The computed result of the previous curve does not affect the next one, which may avoid the graphic distortion caused by the accumulative error. The method can be used to simulate the whole body shape of log approximately by sampling the cross sections along the length direction of log, thus providing a reference model for optimum saw cutting of log.展开更多
Tibetan Plateau（TP）is known as＂Asia’s Water Tower＂,but it remains an interesting question whether the water supply to the north of the plateau is the same with that to the south.Dr.ZHANG Qibin and coworkers from ...Tibetan Plateau（TP）is known as＂Asia’s Water Tower＂,but it remains an interesting question whether the water supply to the north of the plateau is the same with that to the south.Dr.ZHANG Qibin and coworkers from the State Key Laboratory of Vegetation and Environmental Change.CAS Institute of Botany recently tried to answer it from their studies of tree rings.They found evidences for different moisture conditions on the north and south of the plateau during the past five and a half centuries,and particularly,展开更多
基金The research is supported by Project of National Natural Science Foundation of China(30571455)and National "948" Project(2005-4-62)
文摘This paper describes a new method for simulation of the cross section shape of log. The self-developed MQK3102 log shape recognizing machine was used to acquire the finite discrete sampling points on the cross section of log and those points were fitted with the quadratic B-spline parametric curve. This method can clearly stimulate the real shape of the log cross section and is characterized by limited sampling points and high speed computing. The computed result of the previous curve does not affect the next one, which may avoid the graphic distortion caused by the accumulative error. The method can be used to simulate the whole body shape of log approximately by sampling the cross sections along the length direction of log, thus providing a reference model for optimum saw cutting of log.
文摘Tibetan Plateau（TP）is known as＂Asia’s Water Tower＂,but it remains an interesting question whether the water supply to the north of the plateau is the same with that to the south.Dr.ZHANG Qibin and coworkers from the State Key Laboratory of Vegetation and Environmental Change.CAS Institute of Botany recently tried to answer it from their studies of tree rings.They found evidences for different moisture conditions on the north and south of the plateau during the past five and a half centuries,and particularly,
