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排序方式: 共有200条查询结果,搜索用时 15 毫秒
141.
本文报道了用熔融法由常规的单模通信光纤制造宽温工作的低损耗单模光纤定向耦合器.工作波长为1.52μm,分束比为50%的封装器件;工作温度在-30~+70℃范围,分束比容差小于±5%,插入损耗<0.2dB,隔离度>40dB.工作波长的变化对分束比影响十分明显,但入射光的偏振态对其无实际影响. 相似文献
142.
In this paper, we construct a new generalization of Hardy–Berndt sums which are explicit extensions of Hardy–Berndt sums. We express these sums in terms of Dedekind sums s r (h, k : x, y|λ) with x?=?y?=?0 and obtain corresponding reciprocity formulas. 相似文献
143.
We present a design of a low frequency ultra-thin compact and polarization-insensitive metamaterial absorber (MA). The designed MA is a two-layer structure, a periodic array of novel split-ring resonators (SRRs), which are constructed in an FR4 dielectric layer, and another ultra-thin grounded sheet is attached to the bottom. Numerical simulated results show that the proposed MA can realize effective absorption at the frequency 281.9 MHz, and its overall thickness is just only 0.29% of the resonant wavelength, the unit space is only 2.57%, and the absorbanee is kept well for a wide range of incident angles for different polarizations. In addition, the proposed MA is changed into a more compact one when the inter-digital structures are introduced in the SRRs. One convenient experiment is carried out in a rectangular waveguide simulator. 相似文献
144.
D.A. Chestnut C.J.S. De Matos P.C. Reeves-Hall J.R. Taylor 《Optical and Quantum Electronics》2002,34(10):1025-1030
A dual-wavelength, continuous wave, high efficiency fibre Raman ring laser for pumping U-band (1625–1675 nm) fibre Raman amplifiers is demonstrated. Two fibre Bragg gratings were used as wavelength-selective elements resulting in lasing lines at 1529.7 and 1558.7 nm with respective maximum powers of 209.0 and 390.9 mW. A simple U-band Raman amplifier was constructed to test the dual-wavelength pump laser and on:off gain with a peak of 7.3 dB and a 3-dB bandwidth of 73 nm was obtained. 相似文献
145.
A cDNA clone, p14--6, which has an antioncogene activity on the v--Ki--Ras oncogene-transformed malignant cell line DT, was found. This clone was recovered from the revertantR14 cells, which had been isolated by transfections of DT cells with a normal human fibro-blast cDNA library cloned in pcD2, an Okayama-Berg vector. When transfected into DT cells,p14--6 clone gave rise to phenotypical flat reversion in 5--15% of DT transfectant colo-nies. The p14--6--transfected flat cell line, RR, was proven to be a true revertant with signif-icantly reduced malignancy by in ritro and in riro malignancy tests. All other clones recov-ered from R14 cells were unable to cause this reversion. Molecular hybridizations showedthat the p14--6 was inserted into RR genome as tandem repeats, and no structural changewas found in the D--Ki--Ras oncogene in RR genome. These facts suggest that the antioncogeneactivity of the p14--6 clone on the DT cells may be exerted through expression of thecDNA contained in this clone. Possib 相似文献
146.
Gain flattening of an E-band (1360-1460-nm) fiber Raman amplifier was achieved by pump spectral broadening to a 16.3-nm linewidth by use of nonlinearity in a 6.2-km standard fiber. With the broadened pump, the characteristic Raman gain ripple was removed and the 3-dB gain bandwidth was increased by 10.6 nm relative to the nonbroadened pump case. The experimental results agreed well with a gain profile simulation. The use of a 100-m holey fiber for pump broadening was also investigated near 1.56 microm for U-band (1625-1675-nm) Raman amplifiers. Much less broadening was observed, which is believed to be a result of less four-wave mixing. 相似文献
147.
W.F.W. Schneider F. Pühlhofer R.P. Chestnut C. Volant H. Freiesleben W. Pfeffer B. Kohlmeyer 《Nuclear Physics A》1981,371(3):493-509
Mass and Z-distributions of the evaporation residues from compound-nucleus formation in the reaction 5.9 MeV/u 84Kr on 27Al were measured using a time-of-flight ΔE ? E telescope, which is described in detail. The high recoil velocity attained by choosing the heavy reaction partner as projectile made it possible to resolve the reaction products by mass and atomic number. Data were taken in the angular range from 1.5 to 6°. The residue distributions are compared to evaporation calculations assuming the statistical decay by fission and particle evaporation of the compound nucleus 111Mn formed at an excitation energy of 108 MeV with angular momenta up to . The data are consistent with the assumption of statistical equilibrium. Details of the de-excitation process, in particular the fission competition and the influence of nuclear deformations at high angular momenta, are discussed. 相似文献
148.
It is proved that a special case of Feynman identity is a consequence of the generalized Witt identity of some Lie algebra.
Mathematics Subject Classifications (2000): 82B20, 05A19, 17B01. 相似文献
149.
150.