Current Issue : January - March Volume : 2016 Issue Number : 1 Articles : 6 Articles
The hydrodynamics and energetics of bioinspired oscillating mechanisms have received significant attentions by engineers and\nbiologists to develop the underwater and air vehicles. Undulating and pure heaving (or plunging) motions are two significant\nmechanisms which are utilized in nature to provide propulsive, maneuvering, and stabilization forces. This study aims to elucidate\nand compare the propulsive vortical signature and performance of these two important natural mechanisms through a systematic\nnumerical study. Navier-Stokes equations are solved, by a pressure-based finite volume method solver, in an arbitrary Lagrangian-\nEulerian (ALE) framework domain containing a 2D NACA0012 foil moving with prescribed kinematics. Some of the important\nfindings are (1) the thrust production of the heaving foil begins at lower St and has a greater growing slope with respect to\nthe St; (2) the undulating mechanism has some limitations to produce high thrust forces; (3) the undulating foil shows a lower\npower consumption and higher efficiency; (4) changing the Reynolds number (Re) in a constant St affects the performance of the\noscillations; and (5) there is a distinguishable appearance of leading edge vortices in the wake of the heaving foil without observable\nones in the wake of the undulating foil, especially at higher St....
Background. Compliance mismatch is a negative factor and it needs to be considered in arterial bypass grafting. Objective. A\ncomputational model was employed to investigate the effects of arterial compliance mismatch on blood flow, wall stress, and\ndeformation. Methods.The unsteady blood flow was assumed to be laminar,Newtonian, viscous, and incompressible.The vessel wall\nwas assumed to be linear elastic, isotropic, and incompressible.The fluid-wall interaction scheme was constructed using the finite\nelement method. Results. The results show that there are identical wall shear stress waveforms, wall stress, and strain waveforms\nat different locations. The comparison of the results demonstrates that wall shear stresses and wall strains are higher while wall\nstresses are lower at the more compliant section. The differences promote the probability of intimal thickening at some locations.\nConclusions. The model is effective and gives satisfactory results. It could be extended to all kinds of arteries with complicated\ngeometrical and material factors....
The effects of noncovalent bonding and mechanical interlocking of carbon nanotubes (CNT) coating on tensile and interfacial\nstrength of glass fiber were investigated. CNT were coated over glass fiber by a simple dip coating method. Acid treated CNT were\nsuspended in isopropanol solution containing Nafion as binding agent. To achieve uniform distribution of CNT over the glass fiber,\nan optimized dispersion process was developed by two parameters: CNT concentration and soaking time. CNT concentration was\nvaried from 0.4 to 2mg/mL and soaking time was varied from 1 to 180 min. The provided micrographs demonstrated appropriate\ncoating of CNT on glass fiber by use of CNT-Nafion mixture. The effects of CNT concentration and soaking time on coating\nlayer were studied by performing single fiber tensile test and pull-out test. The obtained results showed that the optimum CNT\nconcentration and soaking time were 1mg/mL and 60 min, respectively, which led to significant improvement of tensile strength\nand interfacial shear stress. It was found that, at other concentrations and soaking times, CNT agglomeration or acutely curly tubes\nappeared over the fiber surface which caused a reduction of nanotubes interaction on the glass fiber....
In order to produce nanophotonic elements for smart packaging, we investigated the influence of the parameters of screen and\noffset gravure printing plates on features of printed application of coatings with nanophotonic components and on parameters of\ntheir photoluminescence. To determine the dependence of luminescence intensity on the thickness of solid coating, we carried out\nthe formation of nanophotonic solid surfaces by means of screen printing with different layer thickness on polypropylene film.\nThe obtained analytical dependencies were used to confirm the explanation of the processes that occur during the fabrication of\nnanophotonic coverings with offset gravure printing plates. As a result of experimental studies, it was determined that the different\ncharacter of the dependency of total luminescence intensity of nanophotonic elements from the percentage of a pad is explained by\nthe use of different types of offset gravure printing plates, where the size of raster points remains constant in one case and changes\nin the other case, while the depth of the printing elements accordingly changes or remains constant. To obtain nanophotonic areas\nwith predetermined photoluminescent properties, the influence of investigated factors on changes of photoluminescent properties\nof nanophotonic printed surfaces should be taken into consideration....
FCC (Fluid Catalytic Cracking) catalyst iron poisoning would not only influence units� product slate; when the poisoning is serious,\nit could also jeopardize FCC catalysts� fluidization in reaction-regeneration system and further cause bad influences on units�\nstable operation. Under catalytic cracking reaction conditions, large amount of iron nanonodules is formed on the seriously iron\ncontaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate\nplenty of fines which severely influence units� smooth running. A dense layer could be formed on the catalysts� surface after iron\ncontamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on\ncatalyst�s heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry\nlargely. Research shows that catalyst�s reaction performance would be severely deteriorated when iron content in E-cat (equilibrium\ncatalyst) exceeds 8000 ...
This paper provides a comprehensive review of the use of nanotechnology in architecture that reflects the\nglobal technological movement towards a better built environment. It focuses on the applications and\nfunctions of nanomaterial in architecture. Many products involving nanotechnology are already available,\nand the future applications seem endless in various areas, including energy and material design. Together\nwith architecture, it makes up the nano architecture style, which is the use of nanotechnology in\narchitecture by either the new customized materials or the new shapes and forms of buildings. This paper\npresents some examples for the use of new nanomaterial in existing buildings, which show the limitless\nfeasibility of the application of the technological inventions of the nano sciences. The findings of this\nresearch indicate the importance of promoting the state-of-the-art technologies to the architects of the 21st\ncentury to make them aware of such contemporary issues, and to help maintain the currency and\nsustainability of newly designed buildings....
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