为减轻人工审查MBD(model based definition)模型尺寸标注的劳动强度,对三维尺寸完备性的自动化审查进行了研究。将尺寸完备性问题归结为对相关几何要素是否定形定位的判断问题,建立了对应约束模型记录约束状态;建立了解析尺寸约束和拓...为减轻人工审查MBD(model based definition)模型尺寸标注的劳动强度,对三维尺寸完备性的自动化审查进行了研究。将尺寸完备性问题归结为对相关几何要素是否定形定位的判断问题,建立了对应约束模型记录约束状态;建立了解析尺寸约束和拓扑约束的约束传播规则,并总结了几何约束的解析算法;针对尺寸缺失造成的约束不足,采用打分策略,并以指定基准或指出尺寸缺失的方式主动添加约束;提出了三维尺寸完备性检查的总体算法。通过对3DDFM原型系统的继续开发,并用三维模型实例验证了方法的有效性。展开更多
The Cryogenian Period was first established in 1988 along with other Precambrian eon,era and period-level subdivisions that were defined numerically by Global Standard Stratigraphic Ages(GSSAs).As absolute age constra...The Cryogenian Period was first established in 1988 along with other Precambrian eon,era and period-level subdivisions that were defined numerically by Global Standard Stratigraphic Ages(GSSAs).As absolute age constraints have improved,some of these time intervals no longer bracket adequately the geological event(s),for which they were named.For example,the age discrepancy between the basal Cryogenian GSSA at 850 Ma and the onset of widespread glaciation ca.展开更多
文摘为减轻人工审查MBD(model based definition)模型尺寸标注的劳动强度,对三维尺寸完备性的自动化审查进行了研究。将尺寸完备性问题归结为对相关几何要素是否定形定位的判断问题,建立了对应约束模型记录约束状态;建立了解析尺寸约束和拓扑约束的约束传播规则,并总结了几何约束的解析算法;针对尺寸缺失造成的约束不足,采用打分策略,并以指定基准或指出尺寸缺失的方式主动添加约束;提出了三维尺寸完备性检查的总体算法。通过对3DDFM原型系统的继续开发,并用三维模型实例验证了方法的有效性。
文摘The Cryogenian Period was first established in 1988 along with other Precambrian eon,era and period-level subdivisions that were defined numerically by Global Standard Stratigraphic Ages(GSSAs).As absolute age constraints have improved,some of these time intervals no longer bracket adequately the geological event(s),for which they were named.For example,the age discrepancy between the basal Cryogenian GSSA at 850 Ma and the onset of widespread glaciation ca.
