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排序方式: 共有298条查询结果,搜索用时 31 毫秒
281.
Subenoy Chakraborty Nabajit Chakravarty 《International Journal of Theoretical Physics》2000,39(1):153-157
For an FRW model with a minimally coupled scalar field having hyperbolic(exponential) potential we evaluate the wave function both by solving theWheeler-Dewitt (WD) equation and by evaluating the path integral. The WDequation is solved in configuration as well as in momentum space, while thepath integral is evaluated by dividing the lapse integral into a number of pieces. 相似文献
282.
Ablowitz MJ Biondini G Biswas A Docherty A Hirooka T Chakravarty S 《Optics letters》2002,27(5):318-320
The frequency and timing shifts associated with dispersion-managed solitons in a wavelength-division multiplexed system are computed by the numerically efficient Poisson sum technique. Analytical formulas are attainable by use of this approach with a Gaussian approximation for the soliton. The results are favorably compared with known results for the frequency shift. The method also applies to quasi-linear return-to-zero transmission formats. 相似文献
283.
Periodic-group-delay (PGD) dispersion-compensation modules were recently proposed as mechanisms to alleviate collision-induced timing shifts in dispersion-managed (DM) systems. Frequency and timing shifts in quasi-linear DM systems with PGDs were obtained, and it is shown that significant reductions are achieved when even a small fraction of the total dispersion is compensated for by PGDs. 相似文献
284.
A comparative study of the thermomagnetic memory effects of J
c in two weakly pinned low T
c superconductors, Ca3Rh4Sn13 (CaRhSn) and Yb3Rh4Sn13 (YbRhSn), is presented. In both the systems, the peak effect (PE) phenomenon appears as an order-disorder transformation
through stepwise amorphization of the flux line lattice (FLL). However, in CaRhSn. we can witness another disorder-driven
transition (Bragg glass (BG) to a vortex glass (VG) in a distinct manner as in a single crystal of high T
c YBa2Cu3O7-δ for H‖c. 相似文献
285.
A theoretical analysis of a downstream-mixing 16-μm CO2 gasdynamic laser revealed the possibility of utilizing the downstream-mixing scheme for the generation of 9.4-μm radiation using a CO2 gasdynamic laser. The flow-field has been analyzed using complete two-dimensional, unsteady laminar form of Navier-Stokes
equations coupled with the finite rate vibrational kinetic equations. The analysis showed that integrated small-signal gain
of 11.5m−1 for Lorentzian broadening and 4.8m−1 considering Voigt function can be obtained for N2 reservoir temperature of 2000°K and velocity ratio 1:1 between the CO2 and N2 mixing streams. These results (presented in graphs) clearly highlight the large potential of downstream-mixing CO2 gasdynamic laser for 9.4-μm laser generation. 相似文献
286.
Reaction of 2-(phenylazo)pyridine (pap) with [Ru(PPh3)3X2] (X = Cl, Br) in dichloromethane solution affords [Ru(PPh3)2(pap)X2]. These diamagnetic complexes exhibit a weakdd transition and two intense MLCT transitions in the visible region. In dichloromethane solution they display a one-electron
reduction of pap near − 0.90 V vs SCE and a reversible ruthenium(II)-ruthenium(III) oxidation near 0.70 V vs SCE. The [RuIII(PPh3)2(pap)Cl2]+ complex cation, generated by coulometric oxidation of [Ru(PPh3)2(pap)Cl2], shows two intense LMCT transitions in the visible region. It oxidizes N,N-dimethylaniline and [RuII(bpy)2Cl2] (bpy = 2,2′-bipyridine) to produce N,N,N′,N′-tetramethylbenzidine and [RuIII(bpy)2Cl2]+ respectively. Reaction of [Ru(PPh3)2(pap)X2] with Ag+ in ethanol produces [Ru(PPh3)2(pap)(EtOH)2]2+ which upon further reaction with L (L = pap, bpy, acetylacetonate ion(acac−) and oxalate ion (ox2−)) gives complexes of type [Ru(PPh3)2(pap)(L)]n+ (n = 0, 1, 2). All these diamagnetic complexes show a weakdd transition and several intense MLCT transitions in the visible region. The ruthenium(II)-ruthenium(III) oxidation potential
decreases in the order (of L): pap > bpy > acac− > ox2−. Reductions of the coordinated pap and bpy are also observed. 相似文献
287.
The paper is concerned with the derivation of a two dimensional theory of magneto-elasticity of anisotropic solids with cylindrical hole. The theory has been developed in complex variable formalism and illustrated by considering a particular type of magnetic field.Lastly, the authors are grateful to the Referee for his useful suggestions for the improvement of the paper. 相似文献
288.
289.
R.A. Ganeev A.I. Ryasnyanskiy U. Chakravarty P.A. Naik H. Srivastava M.K. Tiwari P.D. Gupta 《Applied physics. B, Lasers and optics》2007,86(2):337-341
A study of indium nanoparticles prepared by two laser ablation techniques is reported. The suspensions of indium nanoparticles
were prepared using the laser ablation of bulk indium in liquids. The prepared suspensions of indium nanoparticles were analyzed
by the X-ray fluorescence spectroscopy and absorption spectroscopy. The position of the surface plasmon resonance of In-containing
suspensions (350 nm) was consistent with the estimations taking into account the average size of In nanoparticles (43 nm)
measured using the X-ray fluorescence spectroscopy. The nonlinear optical parameters of indium nanoparticles-containing liquids
were studied by the z-scan technique using a picosecond Nd:YAG laser. We compare the laser ablation in liquids with the laser
ablation of indium in vacuum at the tight and weak focusing conditions of a Ti:sapphire laser and analyze the 60 nm indium
nanoparticles synthesized in the latter case.
PACS 42.65.An; 42.65.Hw; 42.65.Jx; 61.46.Df; 78.67.Bf 相似文献
290.
R. A. Ganeev P. A. Naik H. Singhal U. Chakravarty V. Arora J. A. Chakera R. A. Khan M. Raghuramaiah S. R. Kumbhare R. P. Kushwaha P. D. Gupta 《Optics and Spectroscopy》2007,103(5):831-838
The results of investigation of the higher harmonics (from the 21st to the 61st order) of radiation of a femtosecond laser (793 nm, 48 fs) that are generated in silver plasma are presented. The changes in the shape and spectra of harmonics for different chirps of the laser radiation are studied. It is found that the wavelengths of harmonics generated in the region of the plateaulike distribution of the converted radiation intensity can be tuned. It is shown that the conditions of phase matching between harmonics and laser radiation are different for different modulations of the femtosecond pulse spectrum. The tuning range of the spectrum of the converted radiation in the region of lower harmonics, which lie in the beginning region of the plateau, is shown to amount to 0.8 nm. 相似文献