关联规则算法的实现与改进

关联规则作为一种数据挖掘的工具,它能够发现数据项集之间有趣的关联。在关联规则的算法中,Apriori算法是其中的关键算法之一。面对大量复杂的数据集,怎样选择数据结构,怎样优化处理过程,对于此算法的性能将会十分重要。该文首先介绍了关联规则的原理和Apriori算法的实现,然后提出了对该算法的若干改进,例如:采用树型结构存取频繁项集,使用三种缓存优化的方法等。这些优化都能够在整体上提高算法的效率。对于大数据项,试验显示,这些改进能够正确、有效、快速地实现Apriori算法。     

Au NPs@MoS2 Sub‐Micrometer Sphere‐ZnO Nanorod Hybrid Structures for Efficient Photocatalytic Hydrogen Evolution with Excellent Stability

MoS₂ shows promising applications in photocatalytic water splitting, owing to its uniquely optical and electric properties. However, the insufficient light absorption and lack of performance stability are two crucial issues for efficient application of MoS₂ nanomaterials. Here, Au nanoparticles (NPs)@MoS₂ sub‐micrometer sphere‐ZnO nanorod (Au NPs@MoS₂‐ZnO) hybrid photocatalysts have been successfully synthesized by a facile process combining the hydrothermal method and seed‐growth method. Such photocatalysts exhibit high efficiency and excellent stability for hydrogen production via multiple optical‐electrical effects. The introduction of Au NPs to MoS₂ sub‐micrometer spheres forming a core–shell structure demonstrates strong plasmonic absorption enhancement and facilitates exciton separation. The incorporation of ZnO nanorods to the Au NPs@MoS₂ hybrids further extends the light absorption to a broader wavelength region and enhances the exciton dissociation. In addition, mutual contacts between Au NPs (or ZnO nanorods) and the MoS₂ spheres effectively protect the MoS₂ nanosheets from peeling off from the spheres. More importantly, efficiently multiple exciton separations help to restrain the MoS₂ nanomaterials from photocorrosion. As a result, the Au@MoS₂‐ZnO hybrid structures exhibit an excellent hydrogen gas evolution (3737.4 μmol g^?1) with improved stability (91.9% of activity remaining) after a long‐time test (32 h), which is one of the highest photocatalytic activities to date among the MoS₂ based photocatalysts.     

X52管线钢热轧卷板的研制开发

介绍了沙钢对X52管线钢的研制过程，通过化学成分的调整和控轧控冷工艺的不断改进，最终得到了组织、性能都优于X52、达到了X60水平的管线钢。     

Silver-coated silicon nano-particles prepared by thermal decomposition

The silver-coated silicon nano-particles were prepared by thermal decomposition, assisted with post-treatments of electrochemical polishing. Structure and morphology identification indicated the differences between Ag-coated p-type and n-type porous silicon layers were due to their different porosity, and the higher porosity of p-type porous silicon layers was suitable to form the cubic silver particles with nm size. The post-process was used to remove the excess Ag and Ag–O continents from the surface, and the processes were monitored by electric measurement and Raman scattering spectroscopy. The overall change in resistance and Raman spectra revealed the formation of silver-coated silicon nano-particles for p-type porous silicon layer.     

电化学脉冲腐蚀法制备窄峰发射的多孔硅微腔

用电化学脉冲腐蚀方法制备了多孔硅微腔 ,讨论了脉冲电化学腐蚀的参数——周期、占空比对多孔硅多层膜制备的影响 ,并用了以 HF酸扩散为基础的多孔硅动态腐蚀机理对实验结果进行解释 ,认为在用电化学脉冲腐蚀法制备多孔硅微腔的过程中 ,不但要考虑到 HF酸对硅的纵向电流腐蚀 ,也要考虑到 HF酸对多孔硅硅柱的横向浸泡腐蚀 .可通过选取合适的周期、占空比 ,使二者对多孔硅的作用达到适中 ,以制备出高质量的多孔硅多层膜和微腔 .并用正交实验法优化了制备多孔硅微腔的参数 ,根据优化的实验参数 ,制备出了发光峰半峰宽为 6 nm的多孔硅微腔     

胶乳水泥浆体系在剑门1井尾管悬挂固井中的应用

剑门1 井是四川石油管理局承钻的一口重点预探井，该井井底压力高达120 MPa，多次发生气侵、井漏。鉴于此种情况，现场决定四开钻至5004 m 中途完钻，下?177.8 mm 尾管固井。为解决深层高压井尾管固井问题，选用了胶乳水泥浆体系，对该体系的失水控制和防漏失性能、防窜性能、水泥石性能，水泥浆流变性，水泥浆的稳定性、水泥浆稠化时间进行了室内试验。工艺方面采用正注反挤、间歇式低压挤水泥的固井工艺，以减少一次注替静液柱压力过大造成的漏失，易于建立挤水泥压力。经优选水泥浆体系和采用适合该井井况的固井工艺，成功地封隔了 4584~4930 m 4 个严重漏失层，取得了较好的作业效果。剑门1 井?177.8 mm 尾管悬挂固井的成功经验可供此类复杂井固井参考。     

利用Profit Controller实现加热炉支路温度平衡控制

Profit Controller是霍尼韦尔的鲁棒多变量预测控制技术软件包，包括多个超越上一代先进控制软件的专利组件。针对常减压装置中的减压塔进料加热炉，利用Profit Controller实现了加热炉的支路温度平衡和常压塔塔釜的液位控制，取得了显著的控制效果。     

选煤厂煤泥水处理的应用分析

根据选煤厂煤泥水中的细粒含量多，处理困难的特点，通过理论分析和试验研究，阐述了对祁东选煤厂煤泥水处理过程中凝聚剂和絮凝剂的复配作用。     

地铁联络通道冻结法施工中涌水成因及防治

以某富水砂卵石地层联络通道人工冻结法施工为依托,就地层热力学参数、冻结参数和施工工艺等对冻结壁的厚度、交圈时间及平均温度等影响进行了研究,分析表明:AGF冻结效果关于热传导系数的敏感度最大,关于比热容和含水率的敏感度次之;冷冻管间距对冻结效果的影响非常显著,冻结法施工时,应加强冻结管开孔位置及倾斜度的控制;冷冻管直径变大,盐水与地层间对流系数减小,会抵消冻结管直径增大的影响;保温层设置不当以及冻结管远端定位缺陷直接影响联络通道与盾构隧道交叉区域的冻结效果,甚至出现冻结壁厚度不足和冻结壁交圈困难等问题,易导致管片开挖时涌水事故的发生。