Volume 3 Issue 1

Authors: Alok Srivastava; B. S. Bhadauria; I. Hashim

Abstract: The effect of internal heat source on double diffusive convection in a couple stress fluid saturated horizontal anisotropic porous layer was studied analytically by performing linear and nonlinear stability analyses. For linear stability analysis, normal mode technique was used, whereas for nonlinear stability analysis a minimal representation of Fourier series upto two terms was used. Effects of anisotropic parameter, couple stress parameter, solute Rayleigh number, Vadász number, Lewis number, internal heat source parameter on stationary, oscillatory and finite amplitude convection were obtained and shown graphically. Also the graphs for heat and mass transport, streamlines, isotherms, isohalines for steady and unsteady cases were drawn. It was found that internal heat source parameter had destabilizing effect on all modes of convection. Heat transport increased and mass transport decreased with the increase in internal heat source parameter.

Keywords: Internal Heat Source; Double-diffusive Convection; Porous Media; Anisotropic; Couple-stress


Authors: Xiaoping Li; Zhangkang Wu; Guanxia Yu

Abstract: Natural fibers are used to improve mechanical properties of composites materials; research into the influence of the mechanical properties of various fibers’ cell walls on the mechanical properties of composites is very important for producing high-quality composites. The aim of this research is to study the influence of the mechanical properties of tobacco stalk fiber cell wall on the mechanical properties of particle-based panels, comparing the properties of particleboards made with tobacco stalks from different parts of the stem (bottom, midpoint, and top) and treated tobacco stalks from the midpoint of the stem with 1% NaOH solution at 100℃ for 0, 30, 60, and 90 mins, respectively. The results show that the mechanical properties of tobacco stalk fiber cell walls from different parts of the stalk differ and are reduced after the tobacco stalk is treated with 1% NaOH solution. The mechanical properties of the tobacco stalk-based particleboard panels were negatively correlated with the mechanical properties of the tobacco stalk fiber cell wall. After the 1% NaOH treatments of 0-60 min, the middle lamellae were broken, and the mechanical properties of the particleboard were improved; after the 1% NaOH treatment of 90 min, the fiber cell walls were broken and the MOR and MOE of the panels were reduced. Thus, it was concluded that the mechanical properties of fiber cell wall can be reduced to improve the mechanical properties of particleboard panels. The improvement of the mechanical properties of particleboard with no-added- Formaldehyde resin by reducing the mechanical properties of fiber cell wall will be studied in future.

Keywords: Tobacco Stalk; Mechanical Properties of Fiber Cell Wall; NaOH Solution Treatment; Particle Board Panels; Nano-indentation


Authors: Ievgen V. Beliak; Vyacheslav V. Petrov; Dmytro Yu. Manko; Andriy A. Kryuchyn

Abstract: A method which allows separating of parasitic signal at readout system of photoluminescent multilayer disc was proposed. Photoluminescent recording medium based on nanostructured pyrazoline dyes was synthesized. Advanced capabilities for engineering of synthesized luminophors optical properties through laser annealing and doping were analyzed. Stability of synthesized luminophors photoluminescent spectrums was shown.

Keywords: Multilayer Photoluminescent Disc; Recording Medium; Pyrazoline Dye; White Zeolite; Quantum Yield


Authors: Jules Kouam; Abdelhakim Djebara; Victor Songmene

Abstract: In most drilling applications, pre-holes are often performed prior to the final hole drilling in order to obtain holes with good quality (dimensional accuracy, surface finish, and reduced burr). While this operation can improve the process stability, it might however also have an impact on process performance indicators such as dust emission, energy required for the drilling process, cycle time and chip breakability. This work investigates the effects of pre-holes on cutting forces, chip formation, surface finish and dust emission. Aluminum alloys (6061-T6 and 7075-T6) were drilled at different cutting speeds using uncoated HSS drills and the thrust forces, dust emissions and surface finish were analysed. It was found that drilling with pre-holes reduced the cutting forces, improved hole surface finish and chip breakability, and increased the total amount of metallic particle emission.

Keywords: Aluminium; Dry Drilling; Pre-hole; Thrust Forces; Surface Finish; Dust Emissions