This paper advances a new simplified formula for estimating variance components ,sums up the basic law to calculate the weights of observed values and a circulation method using the increaments of weights when estimat...This paper advances a new simplified formula for estimating variance components ,sums up the basic law to calculate the weights of observed values and a circulation method using the increaments of weights when estimating the variance components of traverse nets,advances the charicteristic roots method to estimate the variance components of traveres nets and presents a practical method to make two real and symmetric matrices two diagonal ones.展开更多
Grahne et al. have presented a graph algorithm for evaluating a subset of recursive queries. This method consists of two phases. In the first phase, the method transforms a linear binary-chain program into a set of eq...Grahne et al. have presented a graph algorithm for evaluating a subset of recursive queries. This method consists of two phases. In the first phase, the method transforms a linear binary-chain program into a set of equations over expressions containing predicate symbols. In the second phase, a graph is constructed from the equations and the answers are produced by traversing the relevant paths. A new algorithm is described which requires less time than Grahne’ s. The key idea of the improvement is to reduce the search space that will be traversed when a query is invoked. Further, the evaluation of cyclic data is speeded up by generating most answers directly in terms of the answers already found and the associated 'path information' instead of traversing the corresponding paths as usual. In this way, this algorithm achieves a linear time complexity for both acyclic and most of cyclic data.展开更多
文摘目前,针对聚晶金刚石复合片(Polycrystalline Diamond Compact,PDC)钻头软件的开发主要集中在领眼钻头上,对领眼-扩眼钻头软件的研究还未见报道,并且PDC钻头破岩性能分析常基于有限元仿真分析方法开展,存在效率较低、时间成本大、灵活度不高的局限性,极大地限制了钻头设计研发进度。为此,设计了基于Matlab/图形用户界面(Graphical User Interface,GUI)的领眼-扩眼钻头破岩性能分析平台,旨在提供一个高效的工具,用于领眼-扩眼钻头破岩性能的评估与优化。该平台利用Matlab软件的数值计算和GUI图像处理功能,采用零点遍历法,结合切削齿的切削受力模型,能够计算切削齿的切削参数和领眼-扩眼钻头的受力情况,根据环境地层参数快速优选出最佳的钻扩组合类型,并且分析出领眼-扩眼钻头水力学特性,实现其破岩性能分析功能。结果表明,该软件适应性强、效率高,能在短时间内进行批量化的不同布齿结构领眼-扩眼钻头破岩性能分析,对提高领眼-扩眼钻头设计研发具有重要指导意义。
文摘This paper advances a new simplified formula for estimating variance components ,sums up the basic law to calculate the weights of observed values and a circulation method using the increaments of weights when estimating the variance components of traverse nets,advances the charicteristic roots method to estimate the variance components of traveres nets and presents a practical method to make two real and symmetric matrices two diagonal ones.
文摘Grahne et al. have presented a graph algorithm for evaluating a subset of recursive queries. This method consists of two phases. In the first phase, the method transforms a linear binary-chain program into a set of equations over expressions containing predicate symbols. In the second phase, a graph is constructed from the equations and the answers are produced by traversing the relevant paths. A new algorithm is described which requires less time than Grahne’ s. The key idea of the improvement is to reduce the search space that will be traversed when a query is invoked. Further, the evaluation of cyclic data is speeded up by generating most answers directly in terms of the answers already found and the associated 'path information' instead of traversing the corresponding paths as usual. In this way, this algorithm achieves a linear time complexity for both acyclic and most of cyclic data.
