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91.
92.
Based on straightening the free boundary, a qualocation methodis proposed and analysed for a single phase unidimensional Stefanproblem. This method may be considered as a discrete versionof the H1-Galerkin method in which the discretization is achievedby approximating the integrals by a composite Gauss quadraturerule. Optimal error estimates are derived in L(Wj,), j = 0,1,and L (Hj), j = 0,1,2, norms for a semidiscrete scheme withoutany quasi-uniformity assumption on the finite element mesh. 相似文献
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A simulation analysis of the impact that the nonlinear response of a semiconductor optical amplifier (SOA) has in a four-channel
WDM pre-amplified transmission system is presented in the framework of the recently proposed extended-reach (40-km, 4 × 25 Gb/s)
100 Gb Ethernet link. Channel spacing values ranging from 200 to 800 GHz, and fiber losses between 0 and −20 dB are considered.
A maximum power penalty of 4.5 dB is predicted for short fiber lengths and for the tightest channel plan. For short fiber
lengths, the penalty drops by about 0.8 dB when moving from 400 to 800 GHz; whereas for long fiber lengths, the penalty increases
by 0.2 dB, provided that an average dispersive fiber is utilized. The widely spaced channel plan then represents the best
choice in terms of the analyzed physical effects to implement the next-generation 100 GbE link. Further, our numerical investigation
includes a discrimination analysis that confirms cross-gain modulation as the main overall SOA nonlinear impairment in the
analyzed architecture, and establishes ultra-fast carrier heating-induced FWM as responsible for the system performance difference
observed as a function of channel spacing. The difference practically vanishes for fiber lengths above 30 km. Finally, the
proposal of an equation that fits the simulated power spectrum density of the first-order four-wave mixing-generated product
as a function of channel spacing is presented as an aid to validate our numerical results. 相似文献
95.
近20年来,随着卤化银微晶合成技术的进步,合成出了诸如T-颗粒、核壳乳剂和外延复合颗粒乳剂等性能优异的微晶体,极大地提高了乳剂的感光性能.但这些乳剂也有一个共同的缺点,即大量消耗贵金属银,且未成影像的银均随定影过程而浪费.为改善此类乳剂的不足,各国科... 相似文献
96.
Summary A capillary electrophoretic method for the determination of thiosulphate, bromide, Fe(III)-EDTA chelate and free EDTA in spent
fixing solutions has been developed. Free EDTA was complexed with Ni(II) ions prior to analysis. The optimised separations
were carried out in a fused silica capillary (57 cm×75 μm I.D.) filled with a borate buffer (100mmol L−1 borate, 0.2 mmol L−1 tetradecyltrimethylammonium hydroxide, pH 8.5; applied voltage, −30kV) using direct UV detection at 214 nm. All four anions
were well separated in less than 4 min. The method was applied to the rapid monitoring of spent fixing solutions. 相似文献
97.
采用3-烷基噻吩与对硝基苯甲醛和对二甲氨基苯甲醛的聚合反应得到了5种聚(3-烷基)噻吩取代苯甲烯衍生物:聚(3-丁基)噻吩对硝基苯甲烯(PBTNBQ)、聚(3-己基)噻吩对硝基苯甲烯(PHTNBQ)、聚(3-丁基)噻吩对二甲氨基苯甲烯(PBTDMABQ)、聚(3-己基)噻吩对二甲氨基苯甲烯(PHTDMABQ)和聚(3-辛基)噻吩对二甲氨基苯甲烯(POTDMABQ).计算其光学禁带宽度分别为PBTNBQ(1.82eV),PHTNBQ(1.85eV),PBTDMABQ(1.71eV),PHTDMABQ(1.78eV)和POTDMABQ(1.67eV).利用简并四波混频技术测量了5种聚合物薄膜的三阶非线性极化率,分别为1.74×10-8,1.82×10-8,5.62×10-9,8.64×10-9和1.22×10-8esu,均具有较大的三阶非线性光学性能.针对取代基结构对聚(3-烷基)噻吩取代苯甲烯衍生物的三阶非线性光学性能的影响从分子内极化程度和主链电子的离域程度两个方面进行了讨论. 相似文献
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100.
With the development of the ultra-high speed and large capacity, the channel crosstalk cause by nonlinear effects become more apparent. This paper research the crosstalk produced by refractive index fluctuation nonlinear effects, establish the corresponding mathematical models and physical monitoring models. The experiment simulation results show when the input power is less than 50 mW, the channel crosstalk caused by the nonlinear effects is low and can be ignored; when input power greater than 50 mW, the channel crosstalk caused by the nonlinear effects is more high and affect transmission quality; and with the further increase in power, the channel crosstalk caused by SPM and XPM gradual increase, when the input power is greater than 300 mW, the crosstalk caused by SPM and XPM morn than by FWM. 相似文献