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91.
Flat-top interleavers with chromatic dispersion compensator based on phase dispersive free space Mach-Zehnder interferometer 总被引:2,自引:0,他引:2
In this paper, novel interleavers using circular cavities (CC) in a Mach-Zehnder interferometer (MZI) has been presented and demonstrated for the first time, in which CCs act as phase dispersive mirrors which exhibit a periodic dependence on the frequency of light. Three implementation schemes have been proposed and investigated. Theoretical analysis shows the spectral characteristics of each scheme in a 50-GHz channel spacing application. Furthermore, the chromatic dispersion (CD) of each output comb can be flattened within passband by appending an additional CC. The result shows that the proposed designs with novel interferometer technique can simultaneously provide flat top passbands, high isolation stopband and low CD value as well. 相似文献
92.
半个世纪以来,对半导体技术的深入研究和广泛应用推动了电子工业和信息产业的迅速发展。目前半导体技术正向高速度、高集成化方向发展,但这也不可避免地引发了一系列问题,例如电路中能量损耗过大导致集成片发热,如何进一步将电子器件小型化等。人们由此感到半导体器件的能力已基本达到了极限,转而把目光由电子投向了光子,因为光子有着电子所不具备的优势:速度快,彼此间不存在相互作用,一旦实现用光子替代电子传递信息, 相似文献
93.
?engül Dilem Yard?mc? 《Tetrahedron》2006,62(46):10633-10638
The photooxygenation of the 1-methyl-, 2,3-dimethyl-, and 1,4-dimethylcyclohexa-1,4-dienes, which are readily available through Birch reduction, yielded the corresponding ene-products. The formed endocyclic dienes were trapped by the addition of singlet oxygen to give the corresponding bicyclic endoperoxy hydroperoxides. In the case of 1-methylcyclohexa-1,4-diene and 1,4-dimethylcyclohexa-1,4,-diene, the cis-effect determined the product distribution. Photooxygenation of 2,3-dimethylcyclohexa-1,4-dienes gave mainly exocyclic olefin, which was attributed to the lowered rotational barrier of the methyl group and increased reactivity of the methyl groups. 相似文献
94.
Cr-doped mullites were prepared from single-phase precursors containing up to 9.60 wt% Cr2O3 using a sol-gel technique followed by thermal treatment. Particle induced X-ray emission spectroscopy and X-ray powder diffraction were used to characterize the samples. Mullites were orthorhombic, space group Pbam. Cr doping caused the increase of unit-cell parameters. Strongest expansion was noticed along c-axis followed by a and b (Δc/c=0.089, Δa/a=0.061, Δb/b=0.045% per mole Cr2O3). A second phase, namely θ-(Al,Cr)2O3, was revealed by XRD in the sample containing 9.60 wt% Cr2O3. The structure of mullites was refined by the Rietveld method, location of Cr3+ was performed by the EPR spectroscopy. At low chromium doping level (Cr2O3 content less than ∼5 wt%) Cr3+ ions were substituted for Al3+ in the AlO6 octahedra of the mullite structure (M1 site). For higher doping level, Cr3+ ions were additionally substituted for Al3+ in the AlO6 octahedra of the second phase [θ-(Al,Cr)2O3 at 1400 °C, or α-(Al,Cr)2O3 at 1600 °C] which segregated in the system. Substitution of Cr3+ for Al3+ on M1 site in the mullite structure resulted in increase of average distances in (M1)O6 octahedron and decrease of average distances in T*O4 tetrahedron, while average distances in TO4 tetrahedron stayed almost constant. 相似文献
95.
考虑具常数特征拟线性双曲型方程,提出一个新的可化约方程组的方法,证明了具常特征方程组Cauchy问题经典解的整体存在性定理.同时构造一些例子说明一些有趣的现象. 相似文献
96.
Haitao Zhang Shuxin Ouyang Zhaosheng Li Lifei Liu Tao Yu Jinhua Ye Zhigang Zou 《Journal of Physics and Chemistry of Solids》2006,67(12):2501-2505
Bi2O3/SrTiO3 composite powders have been prepared and their photocatalytic activities were investigated by photooxidation of methanol. These powders were characterized by UV-Visible diffuse reflectance spectra, SEM and X-ray diffraction (XRD). The results revealed that all the Bi2O3/SrTiO3 composite powders exhibited higher photocatalytic activity than pure SrTiO3, Bi2O3 and TiO2 (P25) under visible light irradiation (λ>440 nm). The effects of the Bi2O3 contents on the photocatalytic activities of the composite powders were examined, the photocatalytic activities increased with the content of Bi2O3 increasing to a maximum of 83% and then decreased under visible light irradiation. The effects of the calcination temperatures on the photocatalytic activities of the composite powders were also investigated. 相似文献
97.
I Cserpan M Kalman M L Tj?rnhammar A Simoncsits 《Acta chemica Scandinavica (Copenhagen, Denmark : 1989)》1991,45(3):265-272
A general method to convert single-stranded, chemically synthesized oligonucleotides into cloned duplexes is described. Oligonucleotides supplied with 3'-terminal extensions that are complementary to 3'-protruding ends obtained by certain restriction enzymes can be cloned either directly or with the help of an adapter molecule into double-stranded vectors. Two methods have also been developed for consecutive cloning applications. According to these methods, the synthetic oligonucleotides (and their enzymatically prepared complementary strands) are joined, one after the other, inside a cloning vector, each joining requiring one cloning step. Synthetic genes are thus built up from oligonucleotides corresponding to only one strand of the DNA. The sequential assembly of the cloned duplex takes place in the 5' to 3' direction. Each oligonucleotide is supplied with a four-nucleotide-long 3'-terminal extension, but this sequence is eliminated when the joining takes place, leaving no limiting sequence between the oligonucleotides. The two consecutive cloning methods, the adapter and the polycloning site methods, are illustrated by the assembly of short artificial genes. 相似文献
98.
99.
I. G. Yudelevich B. I. Zaksas Ye. A. Petrova A. S. Cherevko 《Fresenius' Journal of Analytical Chemistry》1991,340(9):560-563
Summary A method for the atomic emission spectrometric analysis of air and water with inductively coupled and two-jet direct current plasmas has been developed. The method has been applied to the determination of impurity contents with good accuracy and sensitivity. 相似文献
100.
We give some sufficient conditions for proper lower semicontinuous functions on metric spaces to have error bounds (with exponents).
For a proper convex function f on a normed space X the existence of a local error bound implies that of a global error bound. If in addition X is a Banach space, then error bounds can be characterized by the subdifferential of f. In a reflexive Banach space X, we further obtain several sufficient and necessary conditions for the existence of error bounds in terms of the lower Dini
derivative of f.
Received: April 27, 2001 / Accepted: November 6, 2001?Published online April 12, 2002 相似文献