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1.
柱形分布的电荷产生的电势   总被引:4,自引:0,他引:4  
李超  周云松 《大学物理》2006,25(5):60-63
将无限长线电荷看成二维平面上的一个“源”,利用电势叠加原理计算了无限长柱形均匀分布的电荷产生的电势.这些柱体的截面电荷分布包括可解析表示和不可求解表示两种,后者可以通过数值计算给出结果.因此这种方法实际上可以计算任意截面柱形电荷分布的电势.通过计算,展示了各种电荷分布所产生电场的特性和共同特征.  相似文献
2.
草地下垫面地表温度与近地面气温的对比研究   总被引:4,自引:0,他引:4  
地表温度是气候系统中的关键参数,它与近地面气温的差异极大地影响着地-气界面上能量和水汽通量的交换。根据大气辐射国际联合观测网合肥站2002年9月至2005年8月三年期间无云晴天的地面观测资料,研究了该地区草地下垫面的地表温度(辐射测温法)和近地面气温的年变化、季节变化和日分布特征。着重讨论了两者差值的变化情况以及两者的相关性,提出了基于近地面气温的地表温度的经验计算方法。研究发现,当地表比辐射率ε的取值范围为0.94~1.00时,ε每改变0.01,草地地表温度的平均变化小于0.2 K。该研究结果可为卫星资料的地面验证提供参考。  相似文献
3.
三棱镜顶角成像之剖析及其应用   总被引:2,自引:0,他引:2  
对分光计测三棱镜顶角实验中观察到的顶角成像进行了剖析,并指出它的简单应用。  相似文献
4.
ICP-AES测定铸铁中的硅、锰、磷、铜   总被引:2,自引:0,他引:2  
李超 《光谱实验室》2004,21(3):556-558
通过微波消解器处理样品 ,优化了实验条件 ,研究了 Si 2 5 1.6 nm、Mn 2 93.9nm、P 2 13.6 nm、Cu32 7.3nm等元素的谱线 ,由此测定铸铁中的硅、锰、磷、铜 ,取得了理想结果。  相似文献
5.
XRF法测定铁矿石中TFe、SiO2和P   总被引:2,自引:0,他引:2  
李超 《光谱实验室》2005,22(2):360-361
四硼酸锂为熔剂 ,钴为内标 ,高温熔融法对铁矿石进行均一处理 ,X射线荧光光谱法测定铁矿石中TFe、Si O2 和 P,取得满意结果。  相似文献
6.
<正>The electronic structures and optical properties of intrinsicβ-Ga2O3 and Zn-dopedβ-Ga2O3 are investigated by first-principles calculations.The analysis about the thermal stability shows that Zn-dopedβ-Ga2O3 remains stable. The Zn doping does not change the basic electronic structure ofβ-Ga2O3,but only generates an empty energy level above the maximum of the valence band,which is shallow enough to make the Zn-dopedβ-Ga2O3 a typical p-type semiconductor.Because of Zn doping,absorption and reflectivity are enhanced in the near infrared region.The higher absorption and reflectivity of ZnCa(2) than those of ZnCa(1)are due to more empty energy states of ZnCa(2)than those of ZnCa(1) near Ef in the near infrared region.  相似文献
7.
中红外超连续谱在氟化物光纤中的产生   总被引:1,自引:0,他引:1  
为获得高功率全光纤中红外超连续谱,采用自制的掺Er锁模光纤激光器作为种子源,激光经过两级放大至1.67W,泵浦氟化物光纤,获得光谱覆盖1000~2400nm的超连续光谱;光谱宽度随着泵浦功率的增加而展宽,当输出功率达到1.21W时,转换效率为72%,并且产生的超连续谱被强烈的调制,在多个波长点处谱功率密度调制到0mW/nm,但调制波长与泵浦功率无关。  相似文献
8.
李超  李芳 《中国物理快报》2006,23(2):470-473
The imaging quality of a lossy left-handed material (LHM) slab is studied. The exact solution is obtained for the interaction of a monochromatic source with a lossy LHM slab by Fourier integrals in wave number domain. It is found that a small amount of loss may have a strong suppression of the super-resolution ability. However, the resolution of a lossy slab can still be better than a conventional lens because the evanescent wave can still be partly restored if the loss is small enough. The localized field with large amplitude (surthce bright spots) near the interfaces of the slab is related to the resonance of the coupling between surface waves at the interfaces, The evanescent wave restoration and the surface bright spots are two relevant phenomena. The distance of the bright spots is close to the half of the resolution length.  相似文献
9.
Wedge-shaped left-handed materials (LHMs) with split ring resonators and wires structures are fabricated by photolithography and lift-off techniques, and the variation of left-handed frequency induced by substrates with different dielectric parameters is investigated. The Snell refraction experiments of the LHM samples are carried out on an angular resoled microwave spectrometer, and the results indicate that the left-handed frequencies of the LHMs shifted downward from 10.57 GHz to 9.74 GHz when the dielectric parameters of the LHM substrates increase from 3.7 to 4.8. Moreover, the finite difference time domain method is used to simulate the microwave transmission properties of the left-handed materials with different substrates, and the experimental results are in agreement with the numerical simulation results. In addition, the reason for the shifting of the left-handed frequency of the LHMs is discussed theoretically.  相似文献
10.
隋强  刘慈香  李超  李芳 《中国物理快报》2005,22(8):2073-2076
The verification and calculation of the negative refractive index of a meta-material is carried out by the finitedifference time-domain method. A slab and a prism of the meta-material are simulated. A genuine plane wave is generated by a two-direction periodic boundary condition (PBC) in the slab model. Based on an advanced phase extraction technique, the negative refractive index of the meta-material is verified by phase velocity measurement in the slab and prism measurement. From our results, not only the phenomenon of backward phase propagation but also the negative refraction is clearly observed. The index is also calculated precisely. The results from the two models are consistent.  相似文献
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