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111.
J. Karátson 《Numerical Functional Analysis & Optimization》2013,34(5-6):590-611
The superlinear convergence of the preconditioned CGM is studied for nonsymmetric elliptic problems (convection-diffusion equations) with mixed boundary conditions. A mesh independent rate of superlinear convergence is given when symmetric part preconditioning is applied to the FEM discretizations of the BVP. This is the extension of a similar result of the author for Dirichlet problems. The discussion relies on suitably developed Hilbert space theory for linear operators. 相似文献
112.
S. Ravi Manoranjan Kar S. M. Borah P. S. R. Krishna 《Crystal Research and Technology》2008,43(12):1318-1322
Neutron powder diffraction patterns were recorded on CaMn1‐xCuxO3 (x = 0 and 0.20) compounds at different temperatures down to 11K. All the patterns were analyzed by employing Rietveld refinement technique and using the Fullprof program. The observed crystallographic peaks could be refined by using Pbnm space group and no structural transition has been observed down to 11K. An additional peak at 2θ = 16.7° has been observed with decrease in temperature below TN and its intensity was found to increase with decrease in temperature. It could be indexed to magnetic (101) plane. The magnetic ordering is found to be G‐type antiferromagnetic behaviour. The magnetic moment at 11K for the samples x = 0.0 and 0.20 are found to be 2.69 and 2.42μB. The doped Cu ions are found to be in Cu2+ state and take part antiferromagnetic interactions with Mn ions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
113.
T. Ghosh S. Bandyopadhyay K. K. Roy S. Kar A. K. Lahiri A. K. Maiti K. Goswami 《Crystal Research and Technology》2008,43(9):959-963
Thermally processed lead iodide (PbI2) thin films were prepared by the vacuum evaporation method in a constant ambient. Measured thickness of the film was verified analytically from the optical transmittance data in a wavelength range between 300 and 1600 nm. From the Tauc relation for the non‐direct inter band transition, the optical band gap of the film was found to be 2.58 eV for film thickness 300 nm. X‐ray diffraction analysis confirmed that PbI2 films are polycrystalline, having hexagonal structure. The low fluctuation in Urbach energy indicates that the grain size is quite small. The present findings are in agreement with the other results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
114.
S. Kar Y. K. Ho 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(2):157-165
We have investigated the bound states and resonance states of
plasma-embedded tdμ and ddμ molecular ions using accurate
correlated basis functions. The plasma effect has been taken care of by
considering the Debye shielding approach of plasma modeling which admits a
variety of plasma conditions. The density of resonance states are calculated
using the stabilization method. The ground and excited states energies, and
the S-wave resonance energies of tdμ and ddμ molecular ions
immersed in plasmas are reported for various shielding parameters, along
with the 1S and 2S threshold energies of the tμ and dμ atoms. 相似文献
115.
Melike Büşra Bayramoğlu Karşı Ercan Berberler 《International journal of environmental analytical chemistry》2019,99(5):428-443
The main aim of this study was to present the effects of barbecue smoke on a small-scale environment, a national park under the influence of intense barbecue smoke, and to scientifically support the sustainable usage of the park. Twelve-weekly bulk deposition samples were collected directly at the barbecuing area, and the samples were analysed for 16 US EPA’s priority PAH compounds and major ions. The mean concentrations of the individual PAHs in the bulk deposition samples ranged from 11.8 ng L?1 (Ane) to 1085 ± 581 ng L?1 (IcdP). The most frequently observed PAH compounds in the bulk deposition samples were Np, Anp, Flr, Phe, An, Flu, BkF, BaP and IcdP. The mean total PAH deposition fluxes were determined as 3.6 ± 5.6 µg m?2 day?1. The chloride, potassium and the sulphate fluxes were determined as 145.2 ± 267.8 µg m?2 day?1, 182.9 ± 291.9 µg m?2 day?1, and 111.9 ± 65.9 µg m?2 day?1, respectively. Dominant ions in the bulk deposition samples were potassium ion, chloride and sulphate which addressed as the fingerprint of barbecue grilling. 相似文献
116.
Karásek V Cizmár T Brzobohatý O Zemánek P Garcés-Chávez V Dholakia K 《Physical review letters》2008,101(14):143601
We create extended longitudinally optically bound chains of microparticles with the use of counterpropagating "nondiffracting" light fields, the so-called Bessel beams. The beam homogeneity and extended propagation range allow the creation of 200 microm long chains of organized microparticles. We observe short-range multistability within a single chain and long-range multistability between several distinct chains. Our observations are supported by theoretical results of the coupled dipole method. 相似文献
117.
Kar S Borghesi M Bulanov SV Key MH Liseykina TV Macchi A Mackinnon AJ Patel PK Romagnani L Schiavi A Willi O 《Physical review letters》2008,100(22):225004
Experimental evidence of plasma jets ejected from the rear side of thin solid targets irradiated by ultraintense (>10(19) W cm(-2)) laser pulses is presented. The jets, detected by transverse interferometric measurements with high spatial and temporal resolutions, show collimated expansion lasting for several hundreds of picoseconds and have substantially steep density gradients at their periphery. The role played by radiation pressure of the laser in the jet formation process is highlighted analytically and by extensive two-dimensional particle-in-cell simulations. 相似文献
118.
A. A. Serafetinides M. Makropoulou E. Fabrikesi E. Spyratou C. Bacharis R. R. Thomson A. K. Kar 《Applied Physics A: Materials Science & Processing》2008,93(1):111-116
The use of intraocular lenses (IOLs) is the most promising method to restore vision after cataract surgery. Several new materials,
techniques, and patterns have been studied for forming and etching IOLs to improve their optical properties and reduce diffractive
aberrations. This study is aimed at investigating the use of ultrashort laser pulses to ablate the surface of PMMA and intraocular
lenses, and thus provide an alternative to conventional techniques. Ablation experiments were conducted using various polymer
substrates (PMMA samples, hydrophobic acrylic IOL, yellow azo dye doped IOL, and hydrophilic acrylic IOL consist of 25% H2O). The irradiation was performed using 100 fs pulses of 800 nm radiation from a regeneratively amplified Ti:sapphire laser
system. We investigated the ablation efficiency and the phenomenology of the ablated patterns by probing the ablation depth
using a profilometer. The surface modification was examined using a high resolution optical microscope (IOLs) or atomic force
microscope—AFM (PMMA samples). It was found that different polymers exhibited different ablation characteristics, a result
that we attribute to the differing optical properties of the materials. In particular, it was observed that the topography
of the ablation tracks created on the hydrophilic intraocular lenses was smoother in comparison to those created on the PMMA
and hydrophobic lens. The yellow doped hydrophobic intraocular lenses show higher ablation efficiency than undoped hydrophobic
acrylic lenses. 相似文献
119.
Somnath Roy Tarak Nath Mandal Anil Kumar Barik Samik Gupta Ray J. Butcher Mohamed Salah El Fallah Javier Tercero Susanta Kumar Kar 《Polyhedron》2008
The synthesis and structure of a pyrazole-based orthogonal ferromagnetically coupled tetracopper(II) 2 × 2 homoleptic grid complex [Cu4(PzOAPyz)4(ClO4)2](ClO4)2 · 6H2O (1), formed by the reaction between the ditopic ligand PzOAPyz and Cu(ClO4)2 · 6H2O, are described. The ligand contains terminal pyrazole and pyrazine residues bound to a central flexible diazine subunit (N–N) as well as one potentially bridging alkoxo group. The two adjacent metal centers are linked by an alkoxo oxygen forming essentially a square Cu4(μ-O4) cluster. In the Cu4(μ-O4) core, out of the four copper centers, two copper centers are penta-coordinated and the remaining two are hexa-coordinated. In each case of hexa-coordination, the sixth position is occupied by one of the oxygen atoms of a coordinated perchlorate ion. Complex 1 has been characterized structurally and magnetically. Although the large Cu–O–Cu bridge angles (137–138°) and short Cu–Cu distances (3.964–3.970 Å) are suitable for the transmission of the expected antiferromagnetic coupling, the square-based Cu4(μ-O4) cluster exhibits an intramolecular ferromagnetic exchange (J = 7.47 cm−1) between the metal centers with an S = 2 magnetic ground state associated with the quasi orthogonal arrangement of the magnetic orbitals (dx2-y2). The exchange pathway parameters have been evaluated from density functional calculations. 相似文献
120.
Tan KT Vogt BD White CC Steffens KL Goldman J Satija SK Clerici C Hunston DL 《Langmuir : the ACS journal of surfaces and colloids》2008,24(17):9189-9193
The origins for abrupt adhesion loss at a critical relative humidity (RH) for polymeric adhesives bonded to inorganic surfaces have been explored using a model poly(methyl methacrylate) (PMMA) film on glass. The interfacial and bulk water concentrations within the polymer film as a function of D 2O partial pressure were quantified using neutron reflectivity. Adhesion strength of these PMMA/SiO 2 interfaces under the same conditions was quantified using a shaft loaded blister test. A drop in adhesion strength was observed at a critical RH, and at this same RH, a discontinuity in the bulk moisture concentration occurred. The moisture concentration near the interface was higher than that in the bulk PMMA, and at the critical RH, the breadth of the interfacial water concentration distribution as a function of distance from the SiO 2/PMMA interface increased dramatically. We propose a mechanism for loss of adhesion at a critical RH based upon the interplay between bulk swelling induced stress and weakening of the interfacial bond by moisture accumulation at the PMMA/SiO 2 interface. 相似文献