排序方式: 共有124条查询结果,搜索用时 15 毫秒
71.
Malihe Yousofzadeh 《代数通讯》2013,41(12):4277-4302
We introduce a new class of possibly infinite dimensional Lie algebras and study their structural properties. Examples of this new class of Lie algebras are finite dimensional simple Lie algebras containing a nonzero split torus, affine and extended affine Lie algebras. Our results generalize well-known properties of these examples. 相似文献
72.
M. Karami M. Raisee S. Delfani M. A. Akhavan Bahabadi A. M. Rashidi 《Optics and Spectroscopy》2013,115(3):400-405
Solar thermal collectors are applicable in the water heating or space conditioning systems in which surface-based absorption of incident solar flux cause high heat losses. Therefore, an enhancement in the efficiency of solar harvesting devices is a basic challenge which requires great effort. Adding nanoparticles to the working fluid in direct absorption solar collector, which has been recently proposed, leads to improvement in the working fluid thermal and optical properties such as thermal conductivity and absorption coefficient. This results certainly in collector efficiency enhancement. In this paper, the characteristics of nanofluids consisting carbon nanoball in water- and ethylene glycol-based suspensions in consideration of their use as sunlight absorber fluid in a DASC are investigated. It was found that by using of 300 ppm carbon nanoballs, the extinction coefficient of pure water and ethylene glycol is increased by about 3.9 cm?1 and 3.4 cm?1 in average, respectively. With these significantly promising optical properties, a direct absorption solar collector using carbon nanoball-based nanofluids can achieve relatively higher efficiencies, compared with a conventional solar collector. 相似文献
73.
The effect of three kinds of surfactants (anionic, cationic and nonionic) on the shape and size distribution of nanoparticles based on soluble starch fabricated under gamma irradiation was studied. Aqueous solution of soluble starch was irradiated with a dose of 20 kGy. The TEM micrograph and size distribution plots showed that when irradiations were made in presence of surfactants the smaller and more distinct nanoparticles were created in comparison to pure starch solution. 相似文献
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75.
Journal of Thermal Analysis and Calorimetry - In this paper, vortex-induced vibration of a circular cylinder with forced convection heat transfer and entropy generation in pulsating... 相似文献
76.
In this paper, orthogonal functions are constructed based on orthogonal polynomials using Kronecker product. In this regard, we present a general formulation for the two-dimensional orthogonal functions and their derivative matrices. These matrices are used in the fully discrete Tau method, on both space and time variables, to reduce the solution of the parabolic partial differential equation (heat conduction) subject to given initial and non-local boundary conditions to the solution of a system of algebraic equations. Illustrative examples are included to demonstrate the validity and applicability of the presented technique. 相似文献
77.
Malihe Yousofzadeh 《代数通讯》2017,45(10):4292-4320
We introduce the notion of locally finite root supersystems as a generalization of both locally finite root systems and generalized root systems. We classify irreducible locally finite root supersystems. 相似文献
78.
Saeed Balalaie Ali Poursaeed Malihe Javan Khoshkholgh Hamid Reza Bijanzadeh Eckardt Wolf 《Comptes Rendus Chimie》2012,15(4):283-289
Immobilized ZrO2-nanopowder (NP) in ionic liquid and different organic solvents was used as a suitable Lewis-acid for the synthesis of polycyclic heterocycles which contains pyran-based skeletons. Reaction of O-propargylated salicylaldehyde with active methylene compounds in the presence of ZrO2-NP in ionic liquid proceeds via domino Knoevenagel hetero Diels-Alder reaction of unactivated alkynes to construct the pyran skeleton. Comparison with different ionic liquids and organic solvents showed that the best results were obtained with 1-butyl-3-methylimidazolium nitrate [bmim][NO3] because of short reaction times and high yields. Carrying out the reaction under these conditions has advantages such as: high yields, short reaction times and easy work-up. 相似文献
79.
Density functional theory calculations were used to study the titanium (Ti) adsorption on perfect and defected (4, 0) BC3 nanotubes, considering Stone–Wales and vacancy defects. The binding energy values for these nanotubes were larger than the corresponding values for carbon nanotubes. The charge transfer from the Ti atom to nanotube was observed for all systems studied. The most exothermic binding process occurred for the Ti adsorption on a native VB defect, which showed minimum structural deformation with respect to a perfect BC3 tube. In the case of a nanotube with a reconstructed carbon vacancy, the adsorption of Ti generated a half-metallic anti-ferromagnet. The results obtained in this paper are relevant for spintronics and hydrogen adsorption applications. 相似文献
80.
This paper treats with K-shortest viable path problem in a transportation network including multiple modes. The considered modes are metro, rapid-bus, private and walking. In this network, a viable path is one that the number of mode changes is limited and the traverse time and also the walking, metro and private usage are restricted subjected to some constraints. The traverse time is defined dependent on congestion level. Because constrained shortest path is NP-hard, we extend two metaheuristic algorithms namely GASA and BACS for the given problem. GASA is a Greedy Algorithm Simulated Annealing and BACS is a bi-direction searching Ant Colony System made by two colonies of ants. We evaluate the validation of these algorithms applying several multimodal random networks. In addition, their results are compared with CPLEX 12.1. We find that GASA is appropriate for small networks and BACS has better performance in median and large-scale networks. Our results on Tehran network also demonstrate that BACS provides better objective values than BACS ones because Tehran public transportation is sparse. 相似文献