A composite particle swarm algorithm for global optimization of multimodal functions

During the last decade, many variants of the original particle swarm optimization （PSO） algorithm have been proposed for global numerical optimization, hut they usually face many challenges such as low solution quality and slow convergence speed on multimodal function optimization. A composite particle swarm optimization （CPSO） for solving these difficulties is presented, in which a novel learning strategy plus an assisted search mechanism framework is used. Instead of simple learning strategy of the original PSO, the proposed CPSO combines one particle＇s historical best information and the global best information into one learning exemplar to guide the particle movement. The proposed learning strategy can reserve the original search information and lead to faster convergence speed. The proposed assisted search mechanism is designed to look for the global optimum. Search direction of particles can be greatly changed by this mechanism so that the algorithm has a large chance to escape from local optima. In order to make the assisted search mechanism more efficient and the algorithm more reliable, the executive probability of the assisted search mechanism is adjusted by the feedback of the improvement degree of optimal value after each iteration. According to the result of numerical experiments on multimodal benchmark functions such as Schwefel, Rastrigin, Ackley and Griewank both with and without coordinate rotation, the proposed CPSO offers faster convergence speed, higher quality solution and stronger robustness than other variants of PSO.     

Electrolyte composition and removal mechanism of Cu electrochemical mechanical polishing

The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization （ECMP） at different pH values including 5-methyl-1H-benzotriazole （TTA）, hydroxyethylidenediphosphoric acid （HEDP）, and tribasic ammonium citrate （TAC） were investigated by electrochemical techniques, X-ray photoelectron spectrometer （XPS） analysis, nano-scratch tests, AFM measurements, and polishing of Cu-coated blanket wafers. The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions, especially at pH=8. The optimal electrolyte compositions （mass fraction） are 6% HEDP, 0.3% TTA and 3% TAC at pH=8. The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential. The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion. The surface topography evolution before and after electrochemical polishing （ECP） illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution, that is, the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate. This understanding is beneficial for optimization of ECMP processes.     

Upper bound limit analysis of roof collapse in shallow tunnels with arbitrary cross sections under condition of seepage force

The analytical solutions for predicting the exact shape of collapse mechanisms in shallow tunnels with arbitrary excavation profiles were obtained by virtue of the upper bound theorem of limit analysis and variation principle according to Hoek-Brown failure criterion. The seepage force was included in the upper bound limit analysis, and it was computed from the gradient of excess pore pressure distribution. The seepage was regarded as a work rate of external force. The numerical results of roof collapse in square and circular tunnels with different rock parameters were derived and discussed, which proves to be valid in comparison with the previous work. The influences of different parameters on the shape of collapsing blocks were also discussed.     

浅层断块油藏水平井CO_2吞吐增油技术

水平井是高尚堡浅层断块油藏的主要开采方式,在水平井开发过程中易形成边底水突进、水窜、水淹,油井含水上升速度快,导致油井产能下降,严重影响油田的开发效果。针对水平井开发后期产能下降的问题,采用了CO2吞吐增油技术。其主要技术原理为:在地层温度条件下CO2能快速溶于原油中,使原油膨胀,改变原油的物性,大幅度降低原油黏度,降低油水界面张力,增加溶解气驱的能量,进而达到油井增产的目的。34井次的现场应用结果证实,水平井单井日产油量由1.72t增加到4.88t,含水率由95.00%下降到51.45%,控水增油效果显著。     

一般空间对象的空间数据类型

空间数据类型的定义一直是空间数据库和GIS等领域的研究热点.针对一般空间对象的空间数据类型定义问题,依据点集和拓扑理论,采用函数方法,研究了一般空间对象的特点,并给出了一组有效时间内的一般空间对象的带时间维的空间数据类型定义,包括一般点,一般线,一般区域.一般空间对象的空间数据类型定义将一般点定义为多个单点的并集;一般线定义为多个连续函数的并集;一般区域定义为多个面的并集.在一般空间对象的空间数据类型基础上,可建立一般空间对象的数据模型,一般空间对象的空间关系,从而在空间查询中,能处理针对一般空间对象的空间查询.     

新型蔗糖基聚羧酸高效减水剂的合成与性能

以自制甲基丙烯酸蔗糖酯（MASE）、丙烯酸（AA）、甲基丙烯酸（MAA）、烯丙基磺酸钠和烯丙基聚乙二醇（A PEG ）为原料,以过硫酸钾为引发剂,自由基共聚法合成蔗糖基聚羧酸高效减水剂。研究了反应时间、蔗糖酯含量及引发剂用量对蔗糖基聚羧酸高效减水剂性能的影响。并通过流动度测试、红外光谱表征及黏度对减水剂的结构与性能进行了分析与比较。各组分物质的量nAA ：nMAA ：nSAS ：nAPEG ：nMASE ＝3∶1∶2∶1∶0．2,MASE含量为4．9wt．％,引发剂为单体用量1．9wt．％,反应时间为5h时合成的减水剂性能最好。在水灰比为0．29,折固掺量为0．3w t ．％,水泥净浆流动度达到340mm。     

基于翻译文体学的实用翻译研究

为了加强实用翻译研究,本文进行了深入细致的探索.以翻译文体学为母论,借鉴关联理论和翻译综合法,指出实用翻译应首先分析语篇类型和文体特征,以最佳关联原则指导翻译实践并调节主体间性,合理采用直译、意译、直译意译结合、创译等翻译方法.研究结果表明,翻译文体学对实用翻译具有较大的指导作用.     

可刚性固定的同振圆柱型矢量水听器的设计

针对同振型矢量水听器使用弹簧悬挂不便的问题,提出一种采用圆环型橡胶弹簧作为悬置元件的新型可刚性固定式同振圆柱型矢量水听器的设计方案。该水听器可直接固定在水下平台用于测量水下声波质点加速度信号。推导了内置加速度计的该型水听器的声压灵敏度表达式。通过理论计算出橡胶弹簧的剪切刚度,并应用有限元软件ANSYS对剪切刚度进行了仿真分析并制作了水听器样机。在0.5~2.5 k Hz的频率范围内,对矢量水听器的声压灵敏度和指向性进行了测量。1 k Hz时,声压灵敏度为-188 d B。测量频带内,指向性凹点深度均大于20 d B。实验结果表明,此种结构的矢量水听器可以实现刚性固定的目的。     

车载气瓶拆装机械手电液控制系统

以车载气瓶拆装机械手为研究对象,分析了其运动特点,并设计一套液压控制驱动及其电器控制系统。实验结果表明该控制系统能够满足车载气瓶拆装线生产需求。     

梳棉机针布选配与工艺优化

探讨了梳棉机针布选配和工艺参数的选择问题。通过工艺对比得出,纺C14.6 tex棉纱时针布选配应按照锡林针布稀、盖板针布密的原则进行。在生条定量3.9 g/m、刺辊速度970 r/min、锡林速度403 r/min工艺条件下,有利于进一步提高成纱质量。