LOD(Level Of Detail,层次细节)技术是解决大规模地形实时渲染的关键技术之一,通过这种技术可以较好地简化场景的复杂度,减少图形显示的失真度,满足一定的实时性要求。传统的算法将四叉树和LOD技术相结合将大规模数字高程模型数据(DEM)...LOD(Level Of Detail,层次细节)技术是解决大规模地形实时渲染的关键技术之一,通过这种技术可以较好地简化场景的复杂度,减少图形显示的失真度,满足一定的实时性要求。传统的算法将四叉树和LOD技术相结合将大规模数字高程模型数据(DEM)进行分块,并对块内数据按照分辨率的大小分层存储。通过对四叉树的研究,在限制性四叉树的基础上引入预处理算法,提高了地形读取速度,增强了实时显示效果。该算法是基于限制性四叉树的一种高效的规则网格划分方法,内存开销少,降低了CPU的负担。实验结果表明该算法提高了地形导入的效率,能实现大规模地形的实时漫游。展开更多
In the present investigation, the relation of pre-ageing temperature and pre-ageing time to mechanical properties was studied, and a model was established to predict the mechanical properties of AA6005 Al alloy. Compa...In the present investigation, the relation of pre-ageing temperature and pre-ageing time to mechanical properties was studied, and a model was established to predict the mechanical properties of AA6005 Al alloy. Compared with the experimental results, the deviation of the proposed model was limited to 8.1%, which showed reasonable accuracy of forecasting. It was found that the performance of AA6005 alloy was better at higher pre-ageing temperature with shorter pre-ageing time than that at T6 temper. The microstructure of the alloy was observed by transmission electron microscopy, and the results showed that high dislocation density and precipitate density existed at 160 ℃ and 200 ℃ pre-ageing, which were in good agreement with the model.展开更多
The predictive model of surface roughness of the spiral bevel gear (SBG) tooth based on the least square support vector machine (LSSVM) was proposed.A nonlinear LSSVM model with radial basis function (RBF) kernel was ...The predictive model of surface roughness of the spiral bevel gear (SBG) tooth based on the least square support vector machine (LSSVM) was proposed.A nonlinear LSSVM model with radial basis function (RBF) kernel was presented and then the experimental setup of PECF system was established.The Taguchi method was introduced to assess the effect of finishing parameters on the gear tooth surface roughness,and the training data was also obtained through experiments.The comparison between the predicted values and the experimental values under the same conditions was carried out.The results show that the predicted values are found to be approximately consistent with the experimental values.The mean absolute percent error (MAPE) is 2.43% for the surface roughness and 2.61% for the applied voltage.展开更多
文摘LOD(Level Of Detail,层次细节)技术是解决大规模地形实时渲染的关键技术之一,通过这种技术可以较好地简化场景的复杂度,减少图形显示的失真度,满足一定的实时性要求。传统的算法将四叉树和LOD技术相结合将大规模数字高程模型数据(DEM)进行分块,并对块内数据按照分辨率的大小分层存储。通过对四叉树的研究,在限制性四叉树的基础上引入预处理算法,提高了地形读取速度,增强了实时显示效果。该算法是基于限制性四叉树的一种高效的规则网格划分方法,内存开销少,降低了CPU的负担。实验结果表明该算法提高了地形导入的效率,能实现大规模地形的实时漫游。
基金Projects(51575539, U1837207) supported by the National Natural Science Foundation of ChinaProject(2020RC2002)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject(2021JJ40774)supported by Natural Science Foundation of Hunan Province,China。
文摘In the present investigation, the relation of pre-ageing temperature and pre-ageing time to mechanical properties was studied, and a model was established to predict the mechanical properties of AA6005 Al alloy. Compared with the experimental results, the deviation of the proposed model was limited to 8.1%, which showed reasonable accuracy of forecasting. It was found that the performance of AA6005 alloy was better at higher pre-ageing temperature with shorter pre-ageing time than that at T6 temper. The microstructure of the alloy was observed by transmission electron microscopy, and the results showed that high dislocation density and precipitate density existed at 160 ℃ and 200 ℃ pre-ageing, which were in good agreement with the model.
基金Project(90923022) supported by the National Natural Science Foundation of ChinaProject(2009220022) supported by Liaoning Science and Technology Foundation,China
文摘The predictive model of surface roughness of the spiral bevel gear (SBG) tooth based on the least square support vector machine (LSSVM) was proposed.A nonlinear LSSVM model with radial basis function (RBF) kernel was presented and then the experimental setup of PECF system was established.The Taguchi method was introduced to assess the effect of finishing parameters on the gear tooth surface roughness,and the training data was also obtained through experiments.The comparison between the predicted values and the experimental values under the same conditions was carried out.The results show that the predicted values are found to be approximately consistent with the experimental values.The mean absolute percent error (MAPE) is 2.43% for the surface roughness and 2.61% for the applied voltage.
