排序方式： 共有41条查询结果，搜索用时 234 毫秒
1.
Fu-Ping Liu Rui-Zhong Li Jin-yao Li Hui-Guo Chen Chang-Chun Yang 《Mathematical Geosciences》2008,40(7):813-829
The group time delay (GTD) formulae of quasi-total reflection of inhomogeneous P-polarized electromagnetic waves (P-PEW, whose electric field parallels to the plane of incidence), caused by the Goos–Hänchen effect, is derived by the phase shift of the wave. A numerical example where the frequency equals to 1 GHz is given. The curves of calculating results show that there are three discontinuous points at the critical angle of phase shift vector, the critical angle of attenuation vector and 90○. When the angle of incidence is equal to one of these three angles, the GTD will become infinite, and the electromagnetic wave will propagate along the interface. The GTD will be very large, when the angle of incidence is close to one of these three angles. The results indicate that there is an important relationship between the two critical angles and the conductivity and permittivity of the two strata, and that the GTD has an important relationship with the angle of incidence. These results can be used to determine the lithology of the strata and to delimit the interfaces of strata more effectively. It is suggested that this research may prove useful in electromagnetic logging analysis and, perhaps, in the design of logging instruments. 相似文献
2.
Regular measurements of the atmospheric ozone in the Brazilian sector were started at Cachoeira Paulista (22.7°S, 45.0°W), and Natal (5.8°S, 35.2°W) in May 1974 and November 1978, respectively. The results of the total ozone measurements carried out at these two stations up to 1981 are presented in this communication and compared with other low-and mid-latitude stations. Although Natal is an equatorial station, it presents a prominent annual variation, and the average total ozone content is high compared to satellite measurements. During 1977–78, abnormally low values of total ozone were observed at Cachoeira Paulista. Some preliminary results about the QBO 9quasi-biennial oscillation) during 1974–81 are also presented. 相似文献
3.
Debiprosad Duari 《Journal of Astrophysics and Astronomy》1997,18(4):441-447
There have been claims, from time to time that there are periodicities in the redshift distribution of quasistellar objects.
These claims are examined from various statistical angles for the 2164 QSO redshifts available in the latest compilation by
Hewitt& Burbidge (1990). The statistical tests reveal moderate to strong evidence for periodicities ξ = 0.0565 and 0.01270-0.129. 相似文献
4.
哈密头苏泉哈尔欣巴A型花岗岩厘定 总被引：1，自引：0，他引：1
初步研究表明新疆哈密头苏泉地区哈尔欣巴花岗岩为A型花岗岩.该岩体富硅(SiO2=71.87%~76.80%)和碱(K2O+N2O=7.39%~8.94%),贫铁、锰、镁(FeOt 0.67%~2.04%;MnO 0.03%~0.06%;MgO 0.10%~0.61%),具较高FeOt/MgO比值,A/NKC=0.78~1.02,属准铝质花岗岩石.在微量元素和稀土元素组成上,岩石富Zr,Rb,Ce等不相容元素,亏损Ni,Co,Cr等元素.10000×Ga/Al为3.12~4.1,大于A型花岗岩下限值(2.6).在Zr,Ce,Nb,Y与10000×Ga/Al,及(Nb+Zr+Ce+Y)/(FeOt/MgO)、SiO2/( FeOt/MgO)图解中大多数点都落在A型花岗岩区域.在A1-A2构造环境判别图上显示后造山花岗岩特征.对头苏泉地区哈尔欣巴A型花岗岩的厘定,为研究该区地壳物质组成及构造演化具重要意义. 相似文献
5.
6.
7.
青藏高原东北隅似三联点构造特征 总被引：27，自引：0，他引：27
在大陆内部,对于一定尺度的构造块体,似三联点构造是一种普通的构造形式。由于大陆内部块体旋转的普遍性,似三联点构造可形成顺旋型和逆旋型两种构造型式。 相似文献
8.
9.
二次曲面拟合法在区域似大地水准面精化中的应用 总被引：1，自引：0，他引：1
以某市为例,介绍了二次曲面拟合法在区域似大地水准面精化中的应用,拟合得到厘米级的似大地水准面模型,并给出有益结论. 相似文献
10.
利用电磁波在导电媒质界面反射系数的附加相角，导出了电场垂直于入射面的非均匀电磁波在导电介质界面的类全反射横向偏移，并对横向偏移进行了相关计算，绘出了横向偏移随入射角的变化曲线. 结果表明：入射角在相移常数临界角、衰减常数临界角和90°处，横向偏移曲线存在三个间断点. 当入射角等于这三个角时，横向偏移为无穷大，即电磁波将沿界面传播；当入射角在这三个角附近时，横向偏移变得非常大. 相似文献