通过对工艺信息实质内容的深入分析,提出一种能全面描述和表达工艺信息的三维工艺模型(Manufacturing process model,MPM),该模型具有工艺过程信息的几何演进性和多视角性特点。模型通过定义MPM三元组,确立了工艺信息的过程性结构关系,...通过对工艺信息实质内容的深入分析,提出一种能全面描述和表达工艺信息的三维工艺模型(Manufacturing process model,MPM),该模型具有工艺过程信息的几何演进性和多视角性特点。模型通过定义MPM三元组,确立了工艺信息的过程性结构关系,可完整表达工艺信息的内在规律,有利于数字化工艺信息的产生与优化。同时,从便于工艺设计等下游后续过程使用工艺信息的角度,提出包括流、动态场景和快照表达模型在内的三维工艺模型的数字化多视角工艺信息表达框架(Manufacturing process as stream and snapshot,MPASS)。其中,流表达模型以制造活动过程之间的关系为组织形式对工艺活动的信息进行表达;动态场景表达则是从不同的对象视角进行投影,以灵活的形式对工艺信息进行组织和查看;快照表达利用静态对象几何和增量的方式,表达动态过程某一时间点的状态值和相关性。不同的表达数据可用于不同的后续制造与管理过程。展开更多
To improve the accuracy and reduce the calcu- lation cost for the inverse problem of centrifugal pump impeller, the new inverse method based on proper orthog- onal decomposition （POD） is proposed. The pump blade sha...To improve the accuracy and reduce the calcu- lation cost for the inverse problem of centrifugal pump impeller, the new inverse method based on proper orthog- onal decomposition （POD） is proposed. The pump blade shape is parameterized by quartic Bezier curve, and the initial snapshots is generated by introducing the perturbation of the blade shape control parameters. The internal flow field and its hydraulic performance is predicted by CFD method. The snapshots vector includes the blade shape parameter and the distribution of blade load. The POD basis for the snap- shots set are deduced by proper orthogonal decomposition. The sample vector set is expressed in terms of the linear combination of the orthogonal basis. The objective blade shape corresponding to the objective distribution of blade load is obtained by least square fit. The Iterative correction algorithm for the centrifugal pump blade inverse method based on POD is proposed. The objective blade load dis- tributions are corrected according to the difference of the CFD result and the POD result. The two dimensional and three dimensional blade calculation cases show that the proposed centrifugal pump blade inverse method based on POD have good convergence and high accuracy, and thecalculation cost is greatly reduced. After two iterations, the deviation of the blade load and the pump hydraulic perfor- mance are limited within 4.0% and 6.0% individually for most of the flow rate range. This paper provides a promising inverse method for centrifugal pump impeller, which will benefit the hydraulic optimization of centrifugal pump.展开更多
针对传统连续数据保护技术中使用的快照存储技术难以高效存储足够多快照的问题,提出了一种新的快照存储技术,即基于凸点集合的快照存储技术(convex point SNAPshot,简称CSNAP).在讨论了CSNAP技术使用的数据结构,并引进了在数据结构中加...针对传统连续数据保护技术中使用的快照存储技术难以高效存储足够多快照的问题,提出了一种新的快照存储技术,即基于凸点集合的快照存储技术(convex point SNAPshot,简称CSNAP).在讨论了CSNAP技术使用的数据结构,并引进了在数据结构中加入指针构成的凸点概念的基础上,分析了凸点集合具有的基本性质,并给出了利用凸点集合储存快照的相关算法,同时还给出了一种使用逆行代价改进CSNAP的方法.最后通过在实际工作负载和随机合成工作负载下的模拟实验说明了,在平均情况下,使用改进的CSNAP技术,可以将快照占用的储存空间减少到传统方法的10%以下.展开更多
文摘通过对工艺信息实质内容的深入分析,提出一种能全面描述和表达工艺信息的三维工艺模型(Manufacturing process model,MPM),该模型具有工艺过程信息的几何演进性和多视角性特点。模型通过定义MPM三元组,确立了工艺信息的过程性结构关系,可完整表达工艺信息的内在规律,有利于数字化工艺信息的产生与优化。同时,从便于工艺设计等下游后续过程使用工艺信息的角度,提出包括流、动态场景和快照表达模型在内的三维工艺模型的数字化多视角工艺信息表达框架(Manufacturing process as stream and snapshot,MPASS)。其中,流表达模型以制造活动过程之间的关系为组织形式对工艺活动的信息进行表达;动态场景表达则是从不同的对象视角进行投影,以灵活的形式对工艺信息进行组织和查看;快照表达利用静态对象几何和增量的方式,表达动态过程某一时间点的状态值和相关性。不同的表达数据可用于不同的后续制造与管理过程。
基金Supported by National Natural Science Foundation of China(Grant Nos.51469014,51676003)National Key Research and Development Program of China(Grant No.20016YFB0200901)
文摘To improve the accuracy and reduce the calcu- lation cost for the inverse problem of centrifugal pump impeller, the new inverse method based on proper orthog- onal decomposition （POD） is proposed. The pump blade shape is parameterized by quartic Bezier curve, and the initial snapshots is generated by introducing the perturbation of the blade shape control parameters. The internal flow field and its hydraulic performance is predicted by CFD method. The snapshots vector includes the blade shape parameter and the distribution of blade load. The POD basis for the snap- shots set are deduced by proper orthogonal decomposition. The sample vector set is expressed in terms of the linear combination of the orthogonal basis. The objective blade shape corresponding to the objective distribution of blade load is obtained by least square fit. The Iterative correction algorithm for the centrifugal pump blade inverse method based on POD is proposed. The objective blade load dis- tributions are corrected according to the difference of the CFD result and the POD result. The two dimensional and three dimensional blade calculation cases show that the proposed centrifugal pump blade inverse method based on POD have good convergence and high accuracy, and thecalculation cost is greatly reduced. After two iterations, the deviation of the blade load and the pump hydraulic perfor- mance are limited within 4.0% and 6.0% individually for most of the flow rate range. This paper provides a promising inverse method for centrifugal pump impeller, which will benefit the hydraulic optimization of centrifugal pump.
文摘针对传统连续数据保护技术中使用的快照存储技术难以高效存储足够多快照的问题,提出了一种新的快照存储技术,即基于凸点集合的快照存储技术(convex point SNAPshot,简称CSNAP).在讨论了CSNAP技术使用的数据结构,并引进了在数据结构中加入指针构成的凸点概念的基础上,分析了凸点集合具有的基本性质,并给出了利用凸点集合储存快照的相关算法,同时还给出了一种使用逆行代价改进CSNAP的方法.最后通过在实际工作负载和随机合成工作负载下的模拟实验说明了,在平均情况下,使用改进的CSNAP技术,可以将快照占用的储存空间减少到传统方法的10%以下.
