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针对目前数据库缓存替换算法替换策略单一,无法预测即将执行SQL语句的不足,提出了一种基于访问图优先的缓存替换算法CG-ABR(Call Graph Optimizing Adaptive Buffer Replacement).该算法通过查询优化器获得当前数据访问类型,自动调整缓存替换算法以适应实时变化的访问类型,改进了缓存访问的管理方法,并根据SQL语句的应用逻辑执行顺序来构造访问图Call Graph,基于Call Graph以预测将要执行的SQL语句,替换出未来不会被访问的页面缓存,以达到缓存空间优化的目的.实验结果与分析表明,CG-ABR算法是有效的,对实时变化的访问类型有较好的缓存命中率,具有良好的应用价值. 相似文献
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An energy-efficient intelligent manufacturing system could significantly save energy compared to traditional intelligent manufacturing systems that do not consider energy issues. Intelligent energy estimation of machining processes is the foundation of the energy-efficient intelligent manufacturing system. This paper proposes a method for machining activity extraction and energy attributes inheritance to support the intelligent energy estimation of machining processes. Fifteen machining activities and their energy attributes are defined according to their operating and energy consumption characteristics. Activities and energy attributes are extracted mainly from NC program supplemented with blank dimensional information. An effective extraction method of activities and energy attributes is the basis for the intelligent energy calculating of machining process. Based on an investigation on the extraction procedure of activities and energy attributes, energy attributes inheritance method is further discussed. Four types of energy attribute inheritance rules are summarized according to the different inheritance characteristics. Based on these four types of inheritance rules, the energy attributes can be transmitted from activity to Therblig as effective inputs of Therblig-based energy model of machining processes. The proposed methodology is finally demonstrated through two machining cases. 相似文献
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Takashi Soga Akihiro Musa Koki Okabe Kazuhiko Komatsu Ryusuke Egawa Hiroyuki Takizawa Hiroaki Kobayashi Shun Takahashi Daisuke Sasaki Kazuhiro Nakahashi 《Computers & Fluids》2011,45(1):215-221
The building-cube method (BCM) is a new generation algorithm for CFD simulations. The basic idea of BCM is to simplify the algorithm in all stages of flow computation to achieve large-scale simulations. Calculation of a pressure field using the Successive Over Relaxation (SOR) method consumes most of the total execution time required for BCM. In this paper, effective implementations on modern vector and scalar processors are investigated. NEC SX-9 and Intel Nehalem-EX are the latest vector and scalar processors. Those processors have much higher peak performances than their previous-generation processors. However, their memory bandwidth improvement cannot catch up with the performance improvement of processors. This is the so-called memory wall problem. In our paper, we discuss optimization techniques for implementation of the SOR method based on architectural characteristics of these modern processors, and evaluate their effects on the sustained performances of these processors for BCM. 相似文献
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A substructure-based finite element model updating technique is proposed in this paper. A few eigenmodes of the independent substructures and their associated derivative matrices are assembled into a reduced eigenequation to recover the eigensolutions and eigensensitivities of the global structure. Consequently, only the concerned substructures and the reduced eigenequation are re-analyzed in the optimization process, thus reducing the computational load of the traditional model updating methods which perform on the global structure. Applications of the proposed substructure-based model updating to a frame structure and a practical bridge demonstrate that the present method is computationally effective and efficient. 相似文献
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为深入研究动平台中心点误差范围,以一种少自由度3-RPS/UPS冗余并联机构为研究对象,提出了一种改进的铰链间隙误差分析方法,分析了此并联机构球铰间隙对动平台中心点的影响,在此基础上提出了一种改进的误差分析方法,并对具有相同结构参数的3一RPS非冗余并联机构和具有冗余支链的3一RPS/UPS并联机构进行误差分析及计算,结果表明,冗余并联机构的误差空间在各方向上都比非冗余并联机构小,故冗余约束可减小误差,提高并联机构精度。 相似文献