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Cuprous oxide nanoclusters, microcubes and microparticles were successfully synthesized by a simple co-precipitation method. Phase purity and crystallinity of the samples were studied by using X-ray powder diffraction. Transmission electron microscopy (TEM) images show different morphologies like nanoclusters, microcubes and microparticles. For linear and nonlinear optical measurements, the as-synthesized Cu2O with different morphologies were dispersed in isopropanol solution. The absorption spectrum recorded in the visible regions shows peaks that depend on the morphology of the particles and the peak shifts towards red region as one goes from nanoclusters to microparticles. Simple open-aperture Z-scan technique is used to measure nonlinear optical properties of cuprous oxide at 532 nm, 30 ps excitation at 10 Hz repetition rate. Cuprous oxide nanoclusters show reverse saturable absorption (RSA) behaviour, the microcubes and microparticles at a similar concentration exhibit saturable absorption (SA) type of behaviour at lower peak intensities and exhibit RSA within SA at higher peak intensities. The results show that the transition from SA to RSA can be ascribed to the two-photon absorption (TPA) process. 相似文献
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Variational aspects of the rate problem in plasticity are discussed,the emphasis being on a unified treatment. Prominence is givento the penalty method; after showing its relationship to othervariational approaches, the question of convergence of penaltyapproximations is addressed, both in a Hilbert space (for theoriginal problem) and in a finite-dimensional subspace, thelatter relating to finite-element approximations. Finally, anexample is given which shows the viability of the penalty methodas a tool for the numerical solution of problems in plasticity. 相似文献
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The unsteady natural convective couple stress fluid flow over a semi-infinite vertical cylinder is analyzed for the homogeneous first-order chemical reaction effect. The couple stress fluid flow model ... 相似文献
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MAHENDRA K VERMA ANANDO CHATTERJEE K SANDEEP REDDY RAKESH K YADAV SUPRIYO PAUL MANI CHANDRA RAVI SAMTANEY 《Pramana》2013,81(4):617-629
Tarang is a general-purpose pseudospectral parallel code for simulating flows involving fluids, magnetohydrodynamics, and Rayleigh–Bénard convection in turbulence and instability regimes. In this paper we present code validation and benchmarking results of Tarang. We performed our simulations on 10243, 20483, and 40963 grids using the HPC system of IIT Kanpur and Shaheen of KAUST. We observe good ‘weak’ and ‘strong’ scaling for Tarang on these systems. 相似文献
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采用燃烧技术制备CuO纳米粒子:一种高效且环境友好的用于芳族醛合成芳族腈催化剂(英文) 总被引:1,自引:0,他引:1
Belladamadu Siddappa ANANDAKUMAR Muthukur Bhojegowd Madhusudana REDDY Chikka Nagaiah THARAMANI Mohamed Afzal PASHA Gujjarahalli Thimmanna CHANDRAPPA 《催化学报》2013,34(4):704-710
CuO nanoparticles were synthesized using an energy-efficient and rapid solution combustion technique with malic acid employed as a fuel. The combustion-derived CuO nanoparticles were used as catalysts in a one-pot synthesis of aromatic nitriles from aromatic aldehydes and hydroxylamine hydrochloride. The catalyst was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, and Brunauer-Emmett-Teller surface area analysis. The catalytic activity of the CuO nanoparticles in the synthesis of aromatic nitriles from aromatic aldehydes was evaluated. The present protocol offers the advantages of a clean reaction, simple methodology, short reaction duration (1-2 min), and high yield (85%-98%). The catalytic activity of the CuO nanoparticles was found to be higher than that of bulk CuO powder under the same conditions. The catalyst can also be recovered and reused up to four times with no significant loss of catalytic activity. The present approach is inexpensive and is a convenient technique suitable for industrial production of CuO nanoparticles and nitriles. 相似文献
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Strong differential subordination and superordination properties are determined for Phi-like functions in the open unit disk by investigating appropriate classes of admissible functions. New strong differential sandwich-type results are also obtained. 相似文献
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Control of fundamental and overtone transitions of a vibration are studied for the diatomic molecule, HCl. Specifically, the results of the effect of variation of the penalty factor on the physical attributes of the system (i.e., probabilities) and pulse (i.e., amplitudes) considering three different pulse durations for each value of the penalty factor are shown and discussed. We have employed the optimal control theory to obtain infrared pulses for selective vibrational transitions. The optimization of initial guess field with Gaussian envelope, phrased as maximization of cost functional, is done using the conjugate gradient method. The interaction of the field with the molecule is treated within the semiclassical dipole approximation. The potential and the dipole moment functions used in the calculations of control dynamics are obtained from high level ab-initio calculations. 相似文献