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141.
We propose optical fibre based filters employing dual-core resonant leaky structure for gain equalization of erbium doped fibre amplifier (EDFA). Spectral loss variation of the structure has been utilized to suppress gain peak and, thus, flatten overall gain profile in the C-band. We show 15.7 dB flat gain with ± 1.6 dB ripple in the wavelength range from 1525 nm to 1555 nm using a single filter and 18±0.7 dB gain using two cascaded filters. 相似文献
142.
Gaurav K. Rastogi B-Shriya Saikia Pallab Pahari Mohit L. Deb Pranjal K. Baruah 《Tetrahedron letters》2019,60(17):1189-1192
Cu(I)/Fe(III) promoted C4-dicarbonylation of 5-aminopyrazole is developed. The strategy involved radical triggered direct oxidative coupling of 5-aminopyrazoles with methyl ketones using aerial oxygen as a source of oxygen in newly generated carbonyl group. CuI is used as catalyst and FeCl3·6H2O is used as additive and the reaction proceeded at 120?°C in DMSO for 9–12?h. It is found that use of Cu(II) catalyst gives the thiomethylated product by reacting with DMSO instead of oxidative coupling. A plausible mechanism is also given. 相似文献
143.
Anand P. Santhanam Yugang Min Sudhir P. Mudur Abhinav Rastogi Bari H. Ruddy Amish Shah Eduardo Divo Alain Kassab Jannick P. Rolland Patrick Kupelian 《Comptes Rendus Mecanique》2010,338(7-8):461-473
A method to estimate the deformation operator for the 3D volumetric lung dynamics of human subjects is described in this paper. For known values of air flow and volumetric displacement, the deformation operator and subsequently the elastic properties of the lung are estimated in terms of a Green's function. A Hyper-Spherical Harmonic (HSH) transformation is employed to compute the deformation operator. The hyper-spherical coordinate transformation method discussed in this paper facilitates accounting for the heterogeneity of the deformation operator using a finite number of frequency coefficients. Spirometry measurements are used to provide values for the airflow inside the lung. Using a 3D optical flow-based method, the 3D volumetric displacement of the left and right lungs, which represents the local anatomy and deformation of a human subject, was estimated from 4D-CT dataset. Results from an implementation of the method show the estimation of the deformation operator for the left and right lungs of a human subject with non-small cell lung cancer. Validation of the proposed method shows that we can estimate the Young's modulus of each voxel within a 2% error level. 相似文献
144.
We design a multi-layer cladding large-core planar waveguide that supports a single guided mode. The waveguide works on the
principle of higher-order mode discrimination. The cladding of the waveguide is formed by alternate low- and high- index regions,
which helps leaking out of higher-order modes while retaining the fundamental mode over the entire length of the waveguide.
The structure is analyzed by the transfer-matrix method and the leakage losses of the modes have been calculated. We show
that a waveguide formed in silica with numerical aperture 0.24 and core width 10 μm can be designed to exhibit single-mode
operation at 1550-nm wavelength. Such a structure should find applications in high-power planar waveguide lasers and amplifiers. 相似文献
145.
A chemical spray pyrolysis technique for deposition of p-type Mg-doped CuCrO2 transparent oxide semiconductor thin films using metaloorganic precursors is described. As-deposited films contain mixed spinel CuCr2O4 and delafossite CuCrO2 structural phases. Reduction in spinel CuCr2O4 fraction and formation of highly crystalline films with single phase delafossite CuCrO2 structure is realized by annealing at temperatures ?700 °C in argon. A mechanism of synthesis of CuCrO2 films involving precursor decomposition, oxidation and reaction between constituent oxides in the spray deposition process is presented. Post-annealed CuCr0.93Mg0.07O2 thin films show high (?80%) visible transmittance and sharp absorption at band gap energy with direct and indirect optical band gaps 3.11 and 2.58 eV, respectively. Lower (∼450 °C) substrate temperature formed films are amorphous and yield lower direct (2.96 eV) and indirect (2.23 eV) band gaps after crystallization. Electrical conductivity of CuCr0.93 Mg0.07O2 thin films ranged 0.6-1 S cm−1 and hole concentration ∼2×1019 cm−3 determined from Seebeck analysis. Temperature dependence of conductivity exhibit activation energies ∼0.11 eV in 300-470 K and ∼0.23 eV in ?470 K region ascribed to activated conduction and grain boundary trap assisted conduction, respectively. Heterojunction diodes of the structure Au/n-(ZnO)/p-(CuCr0.93Mg0.07O2)/SnO2 (TCO) were fabricated which show potential for transparent wide band gap junction device. 相似文献
146.
Shiva K. Rastogi Robert A. Rogers Justin Shi Christopher T. Brown Cindy Salinas Katherine M. Martin Jacob Armitage Christopher Dorsey Gao Chun Peter Rinaldi William J. Brittain 《Magnetic resonance in chemistry : MRC》2016,54(2):126-131
We report through‐space (TS) 19F–19F coupling for ortho‐fluoro‐substituted Z ‐azobenzenes. The magnitude of the TS‐coupling constant (TSJFF) ranged from 2.2–5.9 Hz. Using empirical formulas reported in the literature, these coupling constants correspond to non‐bonded F–F distances (dFF) of 3.0–3.5 Å. These non‐bonded distances are significantly smaller than those determined by X‐ray crystallography or density functional theory, which argues that simple models of 19F–19F TS spin–spin coupling solely based dFF are not applicable. 1H, 13C and 19F data are reported for both the E and Z isomers of ten fluorinated azobenzenes. Density functional theory [B3YLP/6‐311++G(d,p)] was used to calculate 19F chemical shifts, and the calculated values deviated 0.3–10.0 ppm compared with experimental values. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
147.
148.
Alok Kumar Rastogi A. K. Tiwari 《International Journal of Infrared and Millimeter Waves》1993,14(9):1825-1845
A shielded suspended dielectric guide is a dielectric rectangular slab enclosed by regular metallic side walls from all the sides. This type of structure is used in dual mode phase shifter where the size of the normal rectangular wave guide is reduced at the ends, where a dielectric material is embeded in ferrite core. Hence impedance variation of a phase shifter at its transition may be easily calculated using shielded suspended dielectric guide which is a prime parameter for optimum efficiency of wave launching. 相似文献
149.
The dispersion characteristics of Insulated non-radiative dielectric guides are computed using mode matching technique. From the dispersion characteristics the dielectric loss conductor loss and wave impedances are derived. Effect of metallic walls on trapped insulated image guide are also discussed. The dimensions of Insulated non radiative dielectric guide are same as that of rectangular metallic wave guide at ka band. 相似文献
150.
M. Alcolea Palafox V. K. Rastogi Lalit Mittal 《International journal of quantum chemistry》2003,94(4):189-204
This work provides a short survey of the studies carried out on benzonitrile and its derivatives, with special attention on a spectroscopic point of view. The importance and main applications of these molecules are also briefly indicated. For an accurate assignment of their vibrational spectra, the scaling procedures for the wave numbers are described. For this purpose, the performance of semiempirical, ab initio, and density functional methods, with different basis sets, is determined. A “resume” of the main scaling factors to be used in the calculated wave numbers is shown. The results obtained for several benzene derivatives, and in particular for four benzonitriles, are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 189–204, 2003 相似文献