Mining Association Rules Based on Deep Pruning Strategies

Today mobile network and various smart devices flourish rapidly. Data collected from the mobile devices and network can bring us huge opportunities to understand some significant characteristics of the users which traditional data cannot. Association rules mining is an extremely important topic in data mining that can make the utmost value of massive data effectively. Apriori algorithm and the improved Apriori ones based on Boolean matrix are the representative ones in association rules mining. Nevertheless, these solutions have their problems. In this paper, we have proposed an algorithm called MAR-DPS, which has some deep pruning strategies containing three methods to compress the size of frequent itemsets and reduce the joining numbers in generating new frequent itemsets. It can also select the appropriate method to generate frequent 2-itemsets when facing different data sets. Extensive experimental results on three different data sets have demonstrated that our MAR-DPS can perform much better than other tested algorithms.     

Silicon-based on-chip hybrid (de)multiplexers

A review is given on the recent progress of silicon-based on-chip hybrid multiplexers, which are the key elements to enable more than one (de)multiplexing techniques simultaneously, including wavelength-division-multiplexing (WDM), polarization-division-multiplexing (PDM), and mode-division-multiplexing (MDM). This helps enhance the link capacity of optical interconnects multiplexed with many channels. The first part gives a review on the recent developed silicon-based hybrid WDM-PDM (de)multiplexers enabling WDM and PDM simultaneously, which helps achieve 2N channels by introducing N wavelengths and dual polarizations. The recent progress of silicon-based hybrid WDM-MDM (de)multiplexers developed is reviewed in the second part. With the hybrid WDM-MDM (de)multiplexers, one can achieve N×M channels by using N wavelengths and M guided-modes. Finally, the silicon-based hybrid MDM-PDM (de)multiplexers are presented as the key to enhance the link capacity for a single wavelength carrier.     

2Cr13不锈钢表面电火花强化及磨损和冲蚀行为研究

采用电火花表面沉积(ESD)技术,选用YG-8硬质合金和石墨两种电极,对2Cr13不锈钢进行表面强化处理。研究了强化层深度的影响因素,采用辉光放电谱仪(GDS)测试强化层元素分布,用X射线衍射仪(XRD)分析组织结构,用球盘磨损试验机评价耐磨性能,用喷砂型冲蚀装置评价冲蚀性能。结果表明:强化层与基体为冶金结合,其深度随电源电压增加而增大,Ar气保护能有效地降低强化层中N、O含量。石墨电极强化层存在大量的Fe3C、奥氏体和少量石墨;硬质合金电极强化层存在大量的W2C、Co6W6C和WC1-x。经YG-8和C电极强化后,2Cr13不锈钢表面的硬度大幅度提高,摩擦系数明显降低,粘着磨损得到有效的控制,耐磨性能得到显著的改善。在10°小冲蚀角条件下,强化层明显提高了基体的抗石英砂冲蚀性能,而90°垂直冲蚀时,强化层的抗冲蚀性能却不及基体,原因是强化层韧性不及基材。     

Effect of annealing on the microvoid formation and evolution during biaxial stretching of β nucleated isotactic polypropylene

ABSTRACT

Cast films, based on β-iPP, were prepared via melt extrusion, and, then annealed at different temperature. The effect of annealing on the properties of the cast films, as well as on microvoid formation and evolution was investigated. After annealing, the initial lamellar structure was improved, and more secondary crystals were formed which decreased the numbers of tie chains, which was beneficial to cavitation. And the stability of β-crystal and β lamellar thickness distribution was improved. Finally, the membrane obtained by unannealed film had inferior pore-size distribution, while the annealed sample had uniform pore-size distribution.     

基于绝缘体上硅脊型纳米线光波导方向耦合器的TE/TM偏振分束器

利用有限元方法和时域有限差分方法,优化设计了一种结构紧凑的基于绝缘体上硅脊型纳米线光波导方向耦合器的TE/TM偏振分束器。考虑到方向耦合器的波导间隙较小时制作工艺较为困难,且模式失配会引入一些损耗,因此波导间隙取约100nm较为合适。通过优化脊型纳米线光波导的几何尺寸(脊高和脊宽)、耦合区波导间隙,使得偏振分束器长度最短。数值计算结果表明经过优化的偏振分束器最短长度大约为17.3μm,偏振分束器的消光比大于15dB时,波导宽度制作容差为-20～10nm,带宽约为50nm。     

股线品质指标与棉纤维细度的关系

论述了棉纤维细度与股线品质指标之间存在着线性函数相关关系．并通过对大量数据的数理统计学的运算，确立了两个变数间的线位关系、线性关系式──回归方程，从而指导生产实际中确保１４￣ｔ×２股线品质指标在上等水平（２５５０分）以上．     

GC—4超高强度钢腐蚀疲劳断口分维特征的研究

用垂直剖面法研究了GC－4超高强度钢在NaCl水溶液中,不同电化学腐蚀条件下腐蚀疲劳（CF）裂纹亚稳扩展区断口表面的分维特征,并与机械疲劳断口进行了比较。结果发现,弱腐蚀条件下,断口分维值Df与裂纹亚稳扩展速率（da／dN）s之间存在良好的相关性,但相关规律依赖于测量码尺范围;强腐蚀条件下,Df与（da／dN）s之间无明确相关性。同时,Df具有方向性和部位差异性。     

基于FD-BPM方法的阵列波导光栅模拟

给出了一种采用FD-BPM方法对整个阵列波导光栅(AWG)器件进行方便而精确地模拟的方法和一个AWG设计实例的模拟结果,并对模拟结果进行了分析.由模拟得到的器件基本参数与实际设计值符合得很好.     

等离子渗氮与喷丸强化复合改进钛合金抗微动损伤性能

利用直流脉冲等离子电源装置对Ti6A14V钛合金表面渗氮处理,研究了渗氮层的相组成、硬度分布、韧度及摩擦学性能,采用喷丸形变强化(SP)对渗氮层进行后处理,以达到联合提高钛合金微动疲劳(FF)抗力的目的.研究结果表明:脉冲电源等离子技术可在钛合金表面获得由TiN、Ti2N、Ti2A1N等相组成的渗氮层,该改性层能够显著地提高钛合金常规磨损和微动磨损(FW)抗力,但降低了基材的FF抗力.渗氮层的减摩和抗磨性能与SP引入的表面残余压应力协同作用,使钛合金FF抗力超过了SP单独作用.提高渗氮层韧度对改善钛合金FF和FW性能均十分重要.     

Optimal design of an MMI coupler for broadening the spectral response of an AWG demultiplexer

Optimal design of a multimode interference (MMI) coupler for broadening the spectral response of an arrayed-waveguide grating (AWG) demultiplexer is considered. By using a Gaussian beam approximation, an analytical expression for the spectral response of an AWG demultiplexer (with an MMI section) is obtained. A simple analytical formula is derived to relate the optimal MMI length to the separation between the peaks of the twofold images in the MMI region. This peak separation is related to the width of the MMI section. In the proposed design method, a required 1-dB passband width determines the peak separation, which then determines the optimal value for the length of the MMI section according to the analytical formula. The designed flat-top AWG demultiplexer is verified by the beam propagation method.