Experimental study of the effect of slotted blades on the Savonius wind turbine performance

This study investigates the effect of Reynolds number on the performance of Savonius wind turbine with slotted blades. The turbine performance investigation was based on the torque coefficient( Ct), power coefficient( Cp), and tip speed ratio( TSR). The experiment used two number of blade configuration, blade overlap ratio of 10%, 12.5% and 20%, slotted position of 15%, 20%, 25% and 35%, and also slotted gap width of 3 mm, 5 mm, 7 mm, and 9 mm. The wind speed carried out in this experiment are 5.94 m/s, 6.46 m/s, 6.99 m/s, and 7.27 m/s, which are generated from the fan blowers as a wind source. The Savonius turbine with 10% overlap ratio shows the best performance. The highest Cp obtained is 0.138 by the variation of a 3 mm gap with Re of 1.44 × 10~4 and 0.526 TSR.     

Effect of Hall current on MHD mixed convection boundary layer flow over a stretched vertical flat plate

In this paper, the steady magnetohydrodynamic (MHD) mixed convection boundary layer flow of an incompressible, viscous and electrically conducting fluid over a stretching vertical flat plate is theoretically investigated with Hall effects taken into account. The governing equations are solved numerically using an implicit finite-difference scheme known as the Keller-box method. The effects of the magnetic parameter, the Hall parameter and the buoyancy parameter on the velocity profiles, the cross flow velocity profiles and the temperature profiles are presented graphically and discussed. Investigated results indicate that the Hall effect on the temperature is small, and the magnetic field and Hall currents produce opposite effects on the shear stress and the heat transfer at the stretching surface.     

(Ba<Subscript>0.93</Subscript>Nd<Subscript>0.07</Subscript>)TiO<Subscript>3</Subscript> thin films prepared by sol–gel method as a potential dielectric resonator antenna application

In this paper, we report the application of Neodymium (Nd) doped barium titanate thin films (Ba_1-xNd_x) TiO₃ with x = 0 and 0.07 as dielectric resonator antenna. The films were prepared using the sol–gel method and dip-coating technique. Barium acetate, titanium (IV) isopropoxide and neodymium (III) acetate hydrate were used as precursors while glacial acetic acid and acetylacetone were used as solvents. Si wafers were used as a substrate with dipping times varying from 10, 30, and 50 s. The 0.07 films were >800 nm thick and crystallized after being annealed at 800°C for 30 min. The films were tested as dielectric resonator antenna. It was found that, on the actual antenna circuit, the resonant frequency decreased as the (Ba_0.93Nd_0.07) TiO₃ films thickness increased (from 0.8379, to 5.4525 μm). All samples resonate in the range of 8.68–8.83 GHz with quasi omni-directional radiation patterns.     

Modelling of Marangoni convection using proper orthogonal decomposition

Proper orthogonal decomposition (POD) is applied to Marangoni convection in a horizontal fluid layer heated from below and cooled from above with non-deformable free surface. We investigate two-dimensional Marangoni convection for the case of free-slip bottom in the limit of small Prandtl number. The POD technique is then used to the velocity and temperature data to obtain basis functions for both velocity and temperature fields. When these basis functions are used in a Galerkin procedure, the low-dimensional of Marangoni convection are constructed with the smallest possible degree of freedom. The results based on this low-dimensional model are discussed.     

Tensile,Electrical Conductivity,and Morphological Properties of Carbon Black–Filled Epoxy Composites

This work investigates the effect of carbon black content on the tensile, electrical, and morphological properties of epoxy matrix. Carbon black–filled epoxy composites were obtained by mixing the desired amount of carbon black from bamboo stem (BS-CB), oil palm empty fruit bunch (EFB-CB), and coconut shell (CNS-CB) with the epoxy resin. Tensile and electrical properties of carbon black from three different sources (BS-CB, EFB-CB, and CNS-CB) used to fill epoxy composite with 5% filler loading were measured and the results indicated improvement in tensile and electrical properties. The diffraction patterns of X-ray diffraction (XRD) indicated nonlinear crystalline amorphous structure of the CB.     

Thermal behaviors and mechanical properties of halloysite nanotube-reinforced poly(lactic acid) nanocomposites

Poly(lactic acid)/halloysite nanotubes (PLA/HNTs) nanocomposites were prepared using melt compounding followed by compression molding. N,N′-ethylenebis(stearamide) (EBS) was used to improve the dispersion of HNTs and toughen the PLA nanocomposites. The thermal properties of PLA/HNTs nanocomposites were assessed by using differential scanning calorimeter and thermogravimetric analyzer (TG). The TG measurements were performed at both nitrogen and oxygen atmosphere. The mechanical properties of PLA/HNTs were characterized through tensile and impact tests. The morphological properties of the PLA/HNTs nanocomposites were investigated by using transmission electron microscopy and field emission scanning electron microscopy. The degree of crystallinity of PLA nanocomposites was increased slightly by the addition of EBS. The decomposition process of PLA/HNTs depends on the atmosphere reaction during TG test as well as the amount of EBS. The best mechanical properties of PLA/HNTs nanocomposites expressed by the impact strength and elongation at break were achieved by the addition of 5 mass% of EBS.     

Investigating morphological and performance deterioration of injection-molded rice husk–polypropylene composites due to various liquid uptakes

Systematic investigations for the tensile strengths, tensile moduli, flexural strengths, flexural moduli, and impact strengths of various reinforced conditions of rice husk–polypropylene composites under the effect of different liquids uptakes were carried out. Three different liquids, i.e., lubricant oil, sea water, and distilled water, were utilized in this work to investigate their effects on the composites’ mechanical performance. Moreover, morphological analysis of the designed composites was also carried out. Various fiber loadings at 35, 40, 45, 50, and 55 wt% have been designed and investigated. The rice husk–polypropylene composites have been prepared by injection molding, and struktol was used as an additive. The composites were immersed in three different liquids—lubricant oil, sea water, and distilled water—for 4 weeks. The water uptake of rice husk–polypropylene composites for distilled water was the highest compared to lubricant oil and sea water. Moreover, results have demonstrated that mechanical properties of composites immersed in sea water were the best, followed by those immersed in lubricant oil, and then those immersed in distilled water. In addition, it was observed that more voids and pull-out existed in composites immersed in lubricant oil, followed by those immersed in distilled water, and then those immersed in sea water. Tensile moduli showed a reduction trend for all composites with increasing filler loading. However, flexural moduli improved as the filler loading increased. Also, results here demonstrated an optimum filler loading condition for each particular mechanical property of rice husk–polypropylene composites.     

Temperature, salt and solvent effects on intramolecular general base-catalyzed methanolysis of ionized phenyl salicylate (PS?)

The kinetic characteristics of CO, HC and NO_x reaction on different kinds of three way catalysts (TWC) has been investigated by using a fixed bed reactor. It was concluded that the three-way reaction on noble metal catalysts is controlled by internal diffusion at high space velocity 16×10⁴ h^–1. On non-noble metal catalysts internal diffusion control prevails at space velocities (S.V.) <4×10⁴ h^–1 and kinetic control occurs at S.V.> 4×10⁴ h^–1. On non-noble metal catalysts containing a small amount of a noble metal, the kinetic control region of the three-way reaction shifts to higher space velocity.