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101.
An 8-group cross section library is provided to augment a previously published 2-group 3D stylized half-core Canadian deuterium uranium (CANDU) reactor benchmark problem. Reference eigenvalues and selected pin and bundle fission rates are also included. This benchmark is intended to provide computational reactor physicists and methods developers with a stylized model problem in more than two energy groups that is realistic with respect to the underlying physics. In addition to transport theory code verification, the 8-group energy structure provides reactor physicist with an ideal problem for examining cross section homogenization and collapsing effects in a full-core environment. To this end, additional 2-, 4- and 47-group full-core Monte Carlo benchmark solutions are compared to analyze homogenization-free transport approximations incurred as a result of energy group condensation. 相似文献
102.
This paper presents a computational conformational study of side‐chain liquid‐crystal polymers to predict the optical and liquid‐crystalline properties of a series of polyepicholorohrdrin, polyacrylate, poly(methyl acrylate), and polystyrene‐based side‐chain polymers using a Monte Carlo simulation method. Some of the simulated side‐chain polymers were synthesised by chemical modification or polymerisation. The predictive capability of the orientational order parameter has been utilised to predict the liquid‐crystalline isotropic transition temperature of the investigated polymers, which was used to infer the type of distribution in the synthesised polymers. The predictive possibilities of this criterion are explored in the estimation of the nematic–isotropic transition temperatures of the simulated polymers. Evidence is presented to suggest that for side‐chain liquid‐crystalline polymer molecules the nematic to isotropic transition occurs when the order parameter reaches a value of 0.43 according to Maier–Saupe mean‐field theory. Copyright © 2006 Society of Chemical Industry 相似文献
103.
Synthesis and characterization of side-chain maleimide-styrene copolymers with new pendant azobenzene moieties 总被引:1,自引:1,他引:0
Florica Adriana Nicolescu Valentin Victor Jerca Ioan Dancus Adrian Petris Tanta Verona Nicolescu Ileana Brandusa Rau Valentin Ionel Vlad Dan Sorin Vasilescu Dumitru Mircea Vuluga 《Journal of Polymer Research》2011,18(5):1009-1016
Four side-chain maleimide-styrene polymers have been synthesized from maleimide-alt-styrene copolymer (MASt) and some original azo-moieties using polymer analogous reactions. The structures have been obtained
with good yields; remarkably, they showed a high chromophore load, up to ~100%. The polymers were characterized by means of
SEC, FT-IR, 1H-NMR, DSC-TGA, and elemental analysis. The side-chain polymers exhibited improved solubility and enhanced thermal stability
up to 320oC, while their glass transition temperatures have been found to be as high as 210oC. The third-order NLO refraction
(n2) and susceptibility χ(3) coefficients were measured by Z-scan technique. The results of Z-scan measurements showed that the polymers have only nonlinear
refraction, the nonlinear absorption being negligible. 相似文献
104.
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106.
Alexandra Ligia Balan Nicolae Dumitru Alexandru 《AEUE-International Journal of Electronics and Communications》2012,66(11):880-883
In this article a novel method for constructing a family of improved Nyquist filters is provided, as well as some guidelines on how the inter-symbol interference (ISI) problem can be approached. The proposed solution for the design of Nyquist pulses is based on a piece-wise rectangular-polynomial frequency characteristic using second and third degree polynomials. The characteristic property of the novel family of ISI-free pulses generated by the proposed filters is the asymptotic decay rate of t−2. By introducing this approach, comparable or better results are obtained in terms ISI performance as compared to several recently proposed pulses. 相似文献
107.
Samayan Narayanamoorthy Dumitru Baleanu Kalidas Thangapandi Shyam Sanjeewa Nishantha Perera 《IET systems biology》2019,13(6):277
Here, the authors analyse the fractional‐order predator–prey model with uncertainty, due to the vast applications in various ecological systems. The most of the ecological model do not have exact analytic solution, so they proposed a numerical technique for an approximate solution. In the proposed method, they have implemented the higher order term into the fractional Euler method to enhance the precise solution. Further, the present attempt is aimed to discuss the solutions of the FPPM with uncertainty (fuzzy) initial conditions. The initial conditions of the predator–prey model were taken as fuzzy initial conditions due to the fact that the ecological model highly depends on uncertain parameters such as growth/decay rate, climatic conditions, and chemical reactions. Finally, the numerical example manifest that the proposed method is authentic, applicable, easy to use from a computational viewpoint and the acquired outcomes are balanced with the existing method (HPM), which shows the efficiency of the proposed method.Inspec keywords: ecology, fuzzy set theory, predator‐prey systems, approximation theoryOther keywords: ecological model, fractional‐order predator–prey model, ecological systems, approximate solution, higher order term, fractional Euler method, uncertainty initial conditions, fuzzy initial conditions 相似文献
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109.
Tamara Slatineanu Alexandra Raluca Iordan Victor Oancea Mircea Nicolae Palamaru Ioan Dumitru Cristin Petrica Constantin Ovidiu Florin Caltun 《Materials Science and Engineering: B》2013,178(16):1040-1047
Nanocrystalline powders of Co substituted Zn ferrite with the chemical formula CoxZn1−xFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) were synthesized by sol–gel autocombustion method using tartaric acid as fuel agent. The samples were sintered in static air atmosphere for 7 h at 773 K, 7 h at 973 K and 10 h at 1173 K. The organic phase extinction and the spinel phase formation were monitored by means of Fourier transform infrared spectroscopy. The X-ray diffraction patterns analysis confirmed the spinel single phase accomplishment. Crystallite size, average grains size, lattice parameter and cation distribution were estimated. Magnetic behavior of the as-obtained samples by means of M-H hysteresis measurements was studied at room temperature. Permeability and dielectric permittivity at room temperature versus frequency was the subject of a comparative study for the CoxZn1−xFe2O4 series. In agreement with the proposed cation distribution the sample with Co0.8Zn0.2Fe2O4 formula exhibits the optimal magnetic and dielectric properties. 相似文献
110.
An insight on the effect of rubbing textile fiber on morphology of some semi-alicyclic polyimides for liquid crystal orientation 总被引:1,自引:0,他引:1
Andreea Irina Barzic Iuliana Stoica Dumitru Popovici Stelian Vlad Vasile Cozan Camelia Hulubei 《Polymer Bulletin》2013,70(5):1553-1574
Two semi-alicyclic PIs were prepared from bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BOCA) and the aromatic diamines: 4,4′-oxydianiline (ODA) or 4-(4-{[4-(4-aminophenoxy)phenyl]sulfonyl}phenoxy)aniline (pBAPS). The obtained films are transparent in visible domain, having a cut-off wavelength of 294 nm for poly(BOCA–ODA) and 264 nm for poly(BOCA– p BAPS), respectively. Atomic force microscopy images indicate a better surface organization after rubbing with cotton velvet (VC) comparatively with cellulose diacetate (VCD). Contact angle measurements reveal a slight increase of hydrophobicity after patterning as a result of dipolar forces intensification and geometrical constraints of the macromolecular chains. The alignment properties of both PIs, tested with N-(4-methoxybenzylidene)-4-butylaniline, are more obviously for processing with VC. Also, the contrast between the dark and bright states is higher for poly(BOCA– p BAPS)/VC comparatively with poly(BOCA–ODA)/VCD, since its larger surface malleability generates deeper microgrooves. 相似文献