地铁引发低频振动的隔振效果分析

分析了波阻块(WIB)对地铁荷载引发低频振动的隔振效果.首先建立了列车-隧道-地基的数值计算模型,将地铁移动荷载简化为沿隧道向前的移动荷载列,计算了埋设WIB前后场地地表的振动情况,然后对比分析了WIB的埋深和构造对隔振效果的影响,最后与地下连续墙和隔振沟的隔振效果进行了比较.结果表明,对于地铁运行产生的低频振动,WIB可以使地表振级降低5～12 dB,振动幅值降低60%以上,具有比其他隔振措施更好的隔振效果.     

基于模糊控制的黄瓜采摘机器人视觉导航

以温室环境下黄瓜垄间图像为研究对象,提出了基于计算机视觉和模糊控制技术的导航方法.用色差2G-R-B算子对RGB彩色图像进行灰度化处理;根据灰度图像双峰型垂直直方图初步确定导航线位置;并据此逐行求出离散导航点;采用基于一点的改进型Hough变换由离散导航点拟合出导航参考直线,进而获得当前位置的横向偏差和角度偏差作为导航参数.以横向偏差和角度偏差作为模糊控制器的输入,以差速运动机器人的差速值作为输出,设计了模糊控制器.导航试验结果表明:该方法平均耗时小于150 ms,可以满足实时控制的要求,以0.3 m/s速度进行路径跟踪时,最大误差小于5 cm.     

温度对电容器用TiCxN1-x／Al复合铝箔比电容的影响

采用多弧离子镀技术制备高容量电容器用TiCxN1-x/Al复合铝箔电极,研究不同温度下TiCxN1-x/Al复合铝箔的比电容特性,并通过扫描电镜和X射线衍射分析不同温度下铝箔的表面微观结构和物相变化规律.结果表明,TiCxN1-x/Al复合铝箔的比电容高达1 600 μF/cm2,经退火处理后,TiCxN1-x涂层表面颗粒有逐渐长大趋势,晶体结构也从非晶态向晶态转变,当退火温度高于200 ℃时,复合铅箔比电容下降较快.     

碳纤维复合材料低成本多用途发展展望

碳纤堆复合材料低成本是一个主要的发展趋势。本文从发展高性价比碳纤维,制备工艺及成型技术和扩展应用领域等方面对其发展趋势进行论述。     

Design of a new vacuum Compton gamma ray detector with clad metal electron converter plate

A newly designed vacuum Compton gamma-ray detector with Ta-Al clad-metal electron converter plate is described. The detecting efficiency for 1.25 MeV gamma-ray is 7.85×10-3 electron/γ,which is 2.5 times higher than that with Fe converter plate. The designed detector has the merits of well processed and static vacuum keeping and can be used for intense pulsed gamma ray detecting.     

Scattering absorbing method for the detection of 16.7 MeV high energy pulse gamma

Based on theoretical calculation and Monte Carlo simulation,this paper proposes a new method for the diagnosing of 16.7 MeV high-energy pulse gamma,named ＂scattering absorption method＂. The ratio of the sensitivity of high-energy gamma to that of the low-energy background gamma can reach 106 to 108 by this new method. The sensitivity of 16.7 MeV high-energy gamma ranges from 10-21 to 10-16 C·cm^2. It＇s better than the traditional method which is based on the magnetic analyzer and Cherenkov detector on some aspects.     

巴东县三峡工程移民前后外出务工人口状况比较分析

通过对三峡工程移民前后外出务工人口的分析,发现迁移前后对不同途径的外出务工人口影响有显著性区别,即外出务工的途径在迁移前后有所变化.从绝对数来看各种外出务工途径都有所增加,但增加的程度是不同的.外出务工的途径出现多元化.经过对数线性分析发现:不管是迁移前还是迁移后男性外出务工人口的比重都大于女性,但是从迁移后来看,女性外出务工人口比男性增加的速度快一些,说明女性在迁移以后比男性更容易外出务工,通过研究得到结论:一定的环境人口容量下,对于被迫迁入的人口,必然会导致人口流出,人口流出更容易发生在迁入者身上.     

琼州海峡铁路隧道方案初步比选分析

琼州海峡隧道的修建不仅能满足海峡客货运量和国防的需要,而且建成后将会对海南的经济发展起到巨大的拉动作用。琼州海峡隧道前期工作十分紧迫,研究工作量巨大,技术复杂,难度大,所需的时间较长。在研究琼州海峡的气象、水文、地质条件等的基础上,对桥隧方案及隧道线位方案进行了初步比选分析,认为琼州海峡跨海工程宜隧不宜桥,并且Ⅱ线隧道线位方案较优,在对Ⅱ线线位浅埋隧道和深埋隧道的比较后认为浅埋隧道采用盾构法施工的方案较优。由于公路隧道存在诸多技术难题,以及工程造价和运营成本都很高,因此,把铁路隧道方案作为首选方案是可行的     

长江第一隧——武汉长江隧道修建技术

武汉长江隧道是长江上第一条江底隧道。隧道穿越的地质条件复杂,地层透水性强,水压高;盾构直径大,一次推进距离长;地面和地中环境复杂。介绍了武汉长江隧道工程研究与设计经过,工程建设模式,隧道的总体设计、施工概况。着重阐述了盾构的选型和沿线建筑物的保护技术。     

Half-global discretization algorithm based on rough set theory

It is being widely studied how to extract knowledge from a decision table based on rough set theory. The novel problem is how to discretize a decision table having continuous attribute. In order to obtain more reasonable discretization results, a discretization algorithm is proposed, which arranges half-global discretization based on the correlational coefficient of each continuous attribute while considering the uniqueness of rough set theory. When choosing heuristic information, stability is combined with rough entropy. In terms of stability, the possibility of classifying objects belonging to certain sub-interval of a given attribute into neighbor sub-intervals is minimized. By doing this, rational discrete intervals can be determined. Rough entropy is employed to decide the optimal cut-points while guaranteeing the consistency of the decision table after discretization. Thought of this algorithm is elaborated through Iris data and then some experiments by comparing outcomes of four discritized datasets are also given, which are calculated by the proposed algorithm and four other typical algorithms for discritization respectively. After that, classification rules are deduced and summarized through rough set based classifiers. Results show that the proposed discretization algorithm is able to generate optimal classification accuracy while minimizing the number of discrete intervals. It displays superiority especially when dealing with a decision table having a large attribute number.