The effects of rain clutter on millimeter radar performance

The effects of rain clutter on millimeter radar performance are investigated at 35, 94 and 140GHz frequencies, including rain attenuation, radar reflectivity, maximum radar range and equivalent target cross section.     

The quantum Weyl group and the universal quantumR-matrix for affine lie algebraA1(1)

The universal quantumR-matrix is obtained in the case of the affine Kac-Moody Lie algebra sl(2).     

How to improve transmissive optics in the very far infrared?

Conclusion We have presented the possibility to make optical coatings on quartz in the FIR and we have got a transmission coefficient as high as 97% at room temperature. It will rise probably close to 100% at liquid helium temperature where the quartz two-phonon difference processes are frozen. The use of polyethylene or TPX is also possible to make plates and lenses. The reflectivity losses are smaller because the refractive index is much smaller, but they cannot be further reduced by any coating because there is no transparent material with n1.2 in the FIR. These lenses are very useful in the FIR (except around 60 cm^–1 if they are made of polyethylene). TPX is quite transparent over the whole FIR range, and also in the visible with nearly the same refractive index as in the FIR. Alignments can be made with visible light, and still work in the FIR.     

Microwave cavity perturbation technique: Part III: Applications

The resonant cavity perturbation method as described in the preceding two parts of this series is applied to study the electrodynamical properties of different materials in the microwave and millimeter wave spectral range. We briefly discuss the relevant uncertainties which are asociated with the different measurement techniques and we find that employing the amplitude technique it is possible to measure both the width and frequency to nearly the same precision. We then demonstrate the broad range of applicability of this technique by showing results obtained on several different materials, ranging from an insulator to a superconductor. The performance limitations of this technique are discussed in detail.     

The solution of the characteristic equation of circular-rectangular groove guide

Circular-rectangular groove guide is a new type of structure we have presented for coupling between circular groove guide and rectangular groove guide. In this paper, as the continuity of our previous work, the characteristic equation of circular-rectangular groove guide has been solved and the numerical results have been given and discussed.The Project Supported by National Natural Science Foundation of P. R. China     

STUDY OF OPTICAL PUMPING OF ALKALI ATOMIC BEAM IN STRONG MAGNETIC FIELDS

We have gained a very comprehensive set of results for infrared diffraction (10.6μm wavelength) from fabricated single grooves of reflection with widths in the range of 5μm to 65μm. The experimental results show that the diffraction can still occur when the groove width becomes comparable to or less than the wavelength of the probing light. Variations of the diffraction intensities have a very regular sinusoidal relationship with the polarization angle of the incident light; and the diffraction intensities are the when the incident light is TM polarized. However, the diffraction intensities will be a minimum when the incident light is TE polarized; and the biger the diffraction angle, the higher the rate of change of the diffractive intensity with increasing polarization angle of the incident light.     

ELECTRON-ELECTRON CORRELATION IN THE HELIUM 3De DOUBLY EXCITED STATES

The qualitative features of the electron-electron correlation in the helium ³D^e doubly excited states have been investigated via an example of the N = 3, n=4 series. The angular, radial-angular and radial-radial correlations have been shown in detail and the anisotropism of the electronic cloud has been found. The features of the ³D^e states have been compared with those of the L≤1 states.     

A STUDY ON ABSORPTION OF Na ATOMS ON Si(100) 2×1 SURFACES WITH DV-Xα METHOD

The Na absorption on Si(100) 2×1 surface is studied with quantum chemistry molecular cluster method. The calculated results show that the most favourable absorption site of Na is the cave site and the charge transfer of Na atom to Si is large when the Na coverage is smaller than 0.5 monolayer (ML). A Na chain is formed along the cave sites at the 0.5 ML Na coverage, the charge transfer then becomes small. The calculated density of states show that the Na atoms are metallic along the chain. At 1 ML coverage, the Na atoms occupy both the cave and pedestal sites and form a double-layer. There is a charge transfer of 0.5e from each Na atom to the Si surface. The calculated surface energy shows that the saturation absorption of Na on Si surface is 1 ML.     

层状材料中一个简单晶格模型的比热计算

本文采用Born势和简单立方结构计算了层状材料的晶格比热。发现当层伏材料层厚较小时(约在十几层以内),界面态对晶格比热有明显影响。但随层厚增大,比热下降,且基本与界面态及层厚无关。文中还比较了准周期超晶格与周期超晶格两者的晶格比热。 关键词：