Materialized Views Selection of Multi-Dimensional Data in Real-Time Active Data Warehouses

通过基于主动决策引擎日志的数据挖掘来找到分析规则的CUBE 使用模式,从而为多维数据实视图选择算法提供重要依据;在此基础上设计了3A 概率模型,并给出考虑CUBE 受访概率分布的视图选择贪婪算法PGreedy(probability greedy), 以及结合视图挽留原则的视图动态调整算法. 实验结果表明, 在实时主动数据仓库环境下,PGreedy 算法比BPUS(benefit per unit space)算法具有更好的性能. In this paper, data mining based on the log of active decision engine is introduced to find the CUBE using pattern of analysis rules, which can be used as important reference information for materialized views selection. Based on it, a 3A probability model is designed, and the greedy algorithm, called PGreedy (probability greedy), is proposed, which takes into account the probability distribution of CUBE. Also view keeping rule is adopted to achieve better performance for dynamic view adjusting. Experimental results show that PGreedy algorithm can achieve better performance than BPUS (benefit per unit space) algorithm in real-time active data warehouses environment.Supported by the National Natural Science Foundation of China under Grant No.60473051 (国家自然科学基金); the China HP Co. and Peking University Joint Project (北京大学-惠普(中国)合作项目

FABRICATION OF PDMS MICROFLU-IDIC CHIP BY WET ETCHING SILICON

提出一种制作聚二甲基硅氧烷(PDMS)微流控芯片的方法。用15%四甲基氢氧化铵溶液各向异性腐蚀硅(100)制作模具,然后经过浇模,中真空键合得到PDMS微流控芯片。整个过程耗时约10h。用SEM和激光共焦显微成像系统观察整个制作过程。分析了硅片模具及PDMS微流控芯片图案的一致性及粗糙度,结果表明硅片模具图案的相对标准偏差低于3%,表面粗糙度Ra是0.0.51μm,PDMS微流控芯片相应的分别是1%和0.183μm。用PDMS微流控芯片进行电泳分离试验,分离场强200V/cm,在4.7cm长的分离通道中,30s内成功分离了四苯磺酸基卟啉(TPPS)和羧基钴酞菁(TCPcCo(Ⅱ))的混合样品。A method is developed to fabricate polydimethylsi-loxane (PDMS) microfluidic chip. After making the casting mould by anisotropy etehing silicon(100) with 15% (CH3)4NOH, PDMS microfluidic chip can be get by casting and middle vacuum bonding. All procedures are finished in about 10 h. The whole process is monitored by SEM or confocal microscope. The relative standard deviation of micropattems of the silicon mold and PDMS microfuidic chip are under 3% and 1%, the smoothness is 0.051 μm and 0.183 μm respectively. Electro-phoresis separation is carried out on the fabricated PDMS mi-crofluidic chip. Been applied 200 V/cm electric field, the mixture of TPPS and TCPcCo( II) ,is successfully separated within 30 s in 4.7 cm long channel.福建省科技重点资助项目(2003H86)