Current Issue : July - September Volume : 2017 Issue Number : 3 Articles : 6 Articles
The main purpose of this paper is to demonstrate a bionic design for the airfoil of wind turbines inspired by the morphology of\nLong-eared Owl�s wings. Glauert Model was adopted to design the standard blade and the bionic blade, respectively. Numerical\nanalysis method was utilized to study the aerodynamic characteristics of the airfoils as well as the blades. Results show that the\nbionic airfoil inspired by the airfoil at the 50% aspect ratio of the Long-eared Owl�s wing gives rise to a superior lift coefficient and\nstalling performance and thus can be beneficial to improving the performance of the wind turbine blade. Also, the efficiency of the\nbionic blade in wind turbine blades tests increases by 12% or above (up to 44%) compared to that of the standard blade.The reason\nlies in the bigger pressure difference between the upper and lower surface which can provide stronger lift....
To increase the sensitivity of biosensor a new approach using an optical fiber Bragg grating (FBG) coated with a suitable\nnanostructured metal oxide (NMO) is proposed which is costly effective compared to other biosensors. Bragg grating was written\non a D-shaped optical fiber by phasemask method using a 248 nmKrF excimer laser for a 5 min exposure time producing a grating\nwith a period of 528 nm. Titaniumdioxide (TiO2) nanostructured metal oxide was coated over the fiber for the purpose of increasing\nits sensing area. The etched D-shaped FBG was then coated with 312nm thick TiO2 nanostructured layer to ensure propagating\nthe radiation modes within the core. The final structure was used to sense deionized water and saline.The etched D-shaped FBG\noriginal sensitivity before coating to air-deionized water and to air-saline was 0.314 nm/riu and 0.142 nm/riu, respectively. After\ncoating the sensitivity became 1.257 nm/riu for air-deionized water and 0.857 nm/riu for air-saline....
Magnetic and dielectric materials can be blended to enhance absorption properties at\nmicrowave frequencies, although the materials may have relatively weak attenuation capabilities by\nthemselves. The specific goal of this work is to enhance microwave absorption properties of materials\nwith interesting dielectric behavior by blending them with magnetic materials based on transition\nmetals. The synthesized Mn1âË?â??xZnxFe2O4 (x = 0.0 and 1.0) spinel ferrite nanoparticles (MZF NPs)\nwere blended with commercial multi-walled carbon nanotubes (MWCNTs) in various proportions\nwith a binder matrix of paraffin. This simple and efficient process did not cause a significant\nvariation in the energy states of MWCNTs. MZF NPs were synthesized with a citric acid assisted\nsolââ?¬â??gel method. Their electromagnetic characteristics and microwave absorption properties were\ninvestigated. These properties were derived from the microwave scattering parameters measured\nvia the transmission line technique by using a vector network analyzer (VNA) in conjunction with\nan X band waveguide system. The return loss (RL) values of the samples were obtained from the\nelectromagnetic constitutive parameters (permittivity and permeability). The results indicate that the\nminimum RL value and the bandwidth change significantly with the amount of ferrite material in the\nblend. These results encourage further development of MWCNTs blended with ferrite nanoparticles\nfor broadband microwave applications....
Here, we investigate, through parametrically optimized macroscale simulations, the field\nelectron emission from arrays of carbon nanotube (CNT)-coated Spindts towards the development\nof an emerging class of novel vacuum electron devices. The present study builds on empirical data\ngleaned from our recent experimental findings on the room temperature electron emission from large\narea CNT electron sources. We determine the field emission current of the present microstructures\ndirectly using particle in cell (PIC) software and present a new CNT cold cathode array variant which\nhas been geometrically optimized to provide maximal emission current density, with current densities\nof up to 11.5 A/cm2 at low operational electric fields of 5.0 V/�¼m....
In this paper, a novel approach to the synthesis of the carbon nanotubes (CNTs) in reactors\noperating at atmospheric pressure is presented. Based on the literature and our own research results,\nthe most effective methods of CNT synthesis are investigated. Then, careful selection of reagents\nfor the synthesis process is shown. Thanks to the performed calculations, an optimum composition\nof gases and the temperature for successful CNT synthesis in the CVD (chemical vapor deposition)\nprocess can be chosen. The results, having practical significance, may lead to an improvement of\nnanomaterials synthesis technology. The study can be used to produce CNTs for electrical and\nelectronic equipment (i.e., supercapacitors or cooling radiators). There is also a possibility of using\nthem in medicine for cancer diagnostics and therapy....
A nano-patterning approach on silicon dioxide (SiO2) material, which could be used for\nthe selective growth of III-V nanowires in photovoltaic applications, is demonstrated. In this process,\na silicon (Si) stamp with nanopillar structures was first fabricated using electron-beam lithography\n(EBL) followed by a dry etching process. Afterwards, the Si stamp was employed in nanoimprint\nlithography (NIL) assisted with a dry etching process to produce nanoholes on the SiO2 layer.\nThe demonstrated approach has advantages such as a high resolution in nanoscale by EBL and good\nreproducibility by NIL. In addition, high time efficiency can be realized by one-spot electron-beam\nexposure in the EBL process combined with NIL for mass production. Furthermore, the one-spot\nexposure enables the scalability of the nanostructures for different application requirements by tuning\nonly the exposure dose. The size variation of the nanostructures resulting from exposure parameters\nin EBL, the pattern transfer during nanoimprint in NIL, and subsequent etching processes of SiO2\nwere also studied quantitatively. By this method, a hexagonal arranged hole array in SiO2 with a hole\ndiameter ranging from 45 to 75 nm and a pitch of 600 nm was demonstrated on a four-inch wafer....
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