Precorrected-FFT method for EM scattering from composite metallic-dielectric objects

The volume-surface integral equation(VSIE) ,the surface integral equation(SIE) and the volume integral equation(VIE) of EM scattering problem are converted into linear equations with the method of moment,then the precorrected-FFT method is used to solve the linear equations.To overcome the drawback of conventional stencil topology,two kinds of improved stencil topology,stencil topology B and stencil topology C,are presented,and the construction and actual performance of the three kinds of stencil topology a...     

Effects of typhoon Matsa on ionospheric TEC

The effects of typhoon Matsa on the ionosphere are studied by using GPS-TEC data observed at about 50 GPS stations.It is shown that the ionosphere has been already influenced and TEC tends to increase before the landing of Matsa,and the difference of TEC from its monthly median over the typhoon area is about 5 TECU.With the landing of Matsa,both the magnitude and the area of increased TEC decrease.One day after the landing of Matsa,TEC reaches its minimum and is lower than the monthly median.In comparison o...     

U-Pb dating of detrital zircons from the Wudangshan Group in the South Qinling and its geological significance

U-Pb dating was made by the LA-ICP-MS method for detrital zircons from the Wudangshan volcanic-sedimentary succession in the South Qinling. Samples comprise quartz sandstones of the Wudangshan Group collected from the base of the Yangping Formation and an upper layer of the Shuangtai Formation overlain its volcanic sequence, and two river-sand collections from the drainage systems cutting across the two formations, respectively. The results show that the Yangping detrital zircons are dominated by 830–780 Ma grains with a minor population of ~1.0–0.84 Ga and sporadic grains of ~2.6, ~2.4 and 2.0 Ga, whereas the Shuangtai zircons yield an upper intercept age of 763±33 Ma, identical to the timing of the Wudangshan volcanism within error, with few concordant grains of 1.9 and 0.86 Ga. Age spectra for the two river-sand samples are similar to those of the Yangping and Shuangtai Formations, respectively. It thus suggests that the Wudangshan strata are less than 780 Ma, whereas their major detrital zircon populations of 1.0–0.85 Ga and 830–780 Ma are consistent with timing of the Hannan magmatic activities along the northwestern margin of the South China Block. This suggests a Hannan or adjacent area provenance for the Wudangshan strata. The Wudang area is characterized by rift-related igneous events at ~755 and ~680 Ma, respectively, pointing to a tectono- magmatic history different from the Hannan area. It is inferred that the ~755 Ma magmatism is likely to indicate a separation of the South China Block from the supercontinent Rodinia, while the ~680 Ma event suggests a further split between the South Qinling and some unknown continent.     

单针-板电极电晕-介质阻挡放电特性研究

研究以玻璃纤维为填充介质的单针-板电极的电晕-介质阻挡放电特性,测量了放电电压、电流波形,计算了放电功率,比较了有、无玻璃纤维填充时放电电流的差别及放电功率随放电间隙距离、电容电流、放电电压的变化关系,分析了填充介质对针-板电极的电晕-介质阻挡放电特性的影响.研究结果表明:大气压条件下纯空气间隙与有玻璃纤维介质填充时的针-板电极的电晕-介质阻挡放电相比:①后者的放电的起始电压更低,放电功率更大;②后者连续放电电流显著减小,而放电脉冲数量和脉冲电流幅值显著增加;③后者负电晕放电有非常明显的放电脉冲,而前者则主要表现为连续的放电电流.     

台湾海峡及其邻近海域软水母亚纲二新种记述

记述了采自台湾海峡侧丝水母属(Helgicirrha Hartlaub,1909)——卵形侧丝水母,新种(H.ovalis sp.nov.)和采自邻近海域厦门同安湾似杯水母属(Phialella Brown,1902)——厦门似杯水母,新种(P.xiamenensis sp.nov.).这2种鉴别特征如下:卵形侧丝水母,新种,伞扁于半球形,伞薄;胃柄短;生殖腺卵圆形,位于辐管近中部;8条触手,每条触手有3对侧丝,无排泄乳突;每2条触手间1～2个缘疣,各具1对侧丝,其末端有黑色素.厦门似杯水母,新种,伞扁于半球形,伞薄;胃小,口方形;生殖腺球形或椭圆形,悬挂于辐管近伞缘,有中沟;16条空心触手,触手基部球形;8个平衡囊,在伞缘环管垫状疣突上.     

台湾海峡十盘水母属二新种记述(软水母亚纲,锥螅水母目)

根据2007年5月在台湾海峡(20.849°～27.056°N,114.920°～121.241°E)水域采集的标本分析结果,发现了软水母亚纲二新种,即粗手十盘水母,新种(Staurodiscus crassonema sp.nov.)和宽球十盘水母,新种(Staurodiscus latibulbussp.nov.).现将新种形态特征描述如下,为今后编写水螅水母动物志及海洋调查提供参考.     

基于移动性的功率感知路由协议

移动Ad-hoc网络中节点一般由电池提供能量,有效地节约能量显得尤为重要。在功率感知和AODV协议的基础上,提出了一种基于移动性的功率感知路由协议(M-PAR)。协议引入了可用邻居节点平均能量值和节点相对移动性值,选择可用邻居节点平均能量值高,且相对移动性值小的链路作为路由。仿真验证表明:与传统的PAR协议相比,M-PAR协议获得了较好的节能效果,网络生命周期提高了50%。同时,在包投送率、端到端延时取得了较好的改善。     

基于物源特征的白龙江流域泥石流易发性评价

白龙江流域是泥石流地质灾害的易发区和高发区,历史上曾发生过多次泥石流灾害。为探讨物源对泥石流的影响,对流域内泥石流物源数量、类型、分布进行了详细地调查分析,进而研究了物源转化泥石流的方式。在分析泥石流物源发育影响因素的基础上,采用确定性模型与灰色关联组合方法,筛选出物源敏感性、坡面侵蚀程度、沟床比降、沟壑密度四个因子,运用AHP模型进行区域泥石流易发性区划。得出以下认识：(1)白龙江流域泥石流物源分为重力侵蚀堆积型、坡面侵蚀汇集型、沟道侵蚀堆积型和弃渣侵蚀堆积型。其中物源量最多的为重力侵蚀堆积型,分布面积最广的是坡面侵蚀汇集型;(2)泥石流的物源多分布于坡度在15°~45°范围内的斜坡上,1 000~2 500 m的高程范围内,距离断裂500 m范围内,且物源量与植被覆盖率呈较好的负相关性;(3)流域内物源转化为泥石流的方式主要有崩落冲刷拉槽型、集中堵塞溃决型、沟道揭底铲刮型、坡面径流侵蚀溜滑型;(4)白龙江流域泥石流高易发区位于物源分布密集区,即泥石流流域中下游两岸。     

浅析排球副攻手的进攻打法、作用及效果

随着排球运动的发展,快变战术在排球运动技战术体系中的地位和作用越来越重要.排球副攻手作为快变战术的核心,其在排球比赛中作用的发挥越来越受到人们的关注.文章分析了排球副攻手的进攻打法,并对其进攻作用和效果进行了研究.