Improving the quality of surface in the polishing process with the magnetic abrasive powder polishing using a high-frequency induction heating source on CNC table

In this research, polishing flat surfaces has been done by using a completely new and innovative method. In this method, rotary magnetic tool that carry magnetic abrasive powders, is placed in a very strong thermal induction field, and magnetic rotary tool frequently change its direction from clockwise (CW) to counterclockwise (CCW) and CCW to CW. The frequency of changing rotation direction is an important parameter of this innovation method. The intended pieces for polishing operations have been placed on a synchronic two-axis Cartesian CNC table, and the gap between rotary magnetic tool and the sheet surface can be controlled by a power transmission screw operating in the direction of the vertical axis. Several experiments have proved high performance of the new proposed method in the process of polishing.     

Improving the quality of surface in polishing process with the magnetic abrasive powder polishing (MAPP) by use of ultrasonic oscillation of work-piece on a CNC table

In this research work, polishing inside, outside and over the cylindrical parts has been done by using a completely new and innovative method. The work-pieces have been placed on a two-axis Cartesian CNC Table for polishing operations. The Magnetic Rotary Head continuously changes its rotation direction from CW to CCW and CCW to CW and meanwhile the part begin to oscillate up-and-down under a High Frequency (20 kHz) conditions. The Frequency of changing direction From CW to CCW and CCW to CW is one of the important parameters in this method. This method is a kind of Ultrasonic Assisted Polishing (UAP) and novelty of this research work is combining this method with motion of work piece under CNC trajectory with continuously changing direction of Magnetic Rotary Head. Gap between Rotary Magnetic Polishing Head and the Work piece Surface can be controlled by a power transmission screw which operates in the direction of the vertical axis. Several experiments have proved high performance of this new proposed method in the process of polishing in short times.     

Asymmetrical rolling analysis of bonded two-layer sheets and evaluation of outgoing curvature

A theoretical model based on slab method is proposed to analyze asymmetrical rolling of bonded two-layer sheets where the ingoing sheet is forced to horizontally enter the roll gap. Separate equilibrium equations as well as yield relations are derived for each layer by considering different stress fields for the two layers of any slab within the roll gap. A large angle of bite is considered in the governing equations as the experimental data used for verifying the results belong to the rolling conditions where small bite angle assumption is not reasonable. The curvature of the sheet at exit from the roll gap is estimated by studying variations of the normal and the shear strains within the whole roll gap. A very good agreement is shown to exist between the rolling force as well as the outgoing curvature predicted by the present model and the available analytical and experimental results reported by other investigators. By studying the outgoing curvature at different conditions, some practical suggestions to minimize the strip curvature at exit from the roll gap are proposed.     

Optimum lipid production using agro-industrial wastewater treated microalgae as biofuel substrate

Abundant wastewater discharges from palm oil industries in tropical nations being a valuable resource of biodiesel need proper exploration. Research hinted that such wastewater as economical nutrient source or substrate can support the cultivation of microalgae. In this experiment, we have tested the growth and lipid production of five different microalgal strains in palm oil mill effluent (POME). POME as a biofuel substrate is demonstrated to be lucrative for microalgae-assisted lipids production. POME is rich in macro- and micronutrients can be used as a growth medium for algal growth in order to reduce the growth medium cost and environmental pollutions. Among the five microalgal strains tested, Chlorella sorokiniana revealed optimum biomass and lipid production. The productivity was evaluated in terms of chlorophyll content, growth rate, biomass, and lipid content, which discerned to be 0.099/day, 8.0 mg/L day and 2.68 mg/mg cell dry weight (CDW). Furthermore, in this study, an optimization study was carried out to enhance the microalgae to produce high lipid content using carbon-to-nitrogen ratio and different light/dark periods. The presence of nitrogen combined glucose (with a carbon-to-nitrogen ratio 100:7) as an alternative source to carbon displayed higher lipid production of 2.68 (mg/mg CDW) by C. sorokiniana. This study confirms that 8:16 h light/dark condition at C:TN ratio of 100:7 supported to produce high lipid content of 17 mg lipid/mg CDW. The above results revealed that POME could be a suitable growth media for the alga C. sorokiniana to improve the maximum lipid yield for biofuels production.     

Solution of the second-order one-dimensional hyperbolic telegraph equation by using the dual reciprocity boundary integral equation (DRBIE) method

In this paper, we use a numerical method based on the boundary integral equation (BIE) and an application of the dual reciprocity method (DRM) to solve the second-order one space-dimensional hyperbolic telegraph equation. Also the time stepping scheme is employed to deal with the time derivative. In this study, we have used three different types of radial basis functions (cubic, thin plate spline and linear RBFs), to approximate functions in the dual reciprocity method (DRM). To confirm the accuracy of the new approach and to show the performance of each of the RBFs, several examples are presented. The convergence of the DRBIE method is studied numerically by comparison with the exact solutions of the problems.     

Adsorption of BSA onto hexagonal mesoporous silicate loaded by APTES and tannin: Isotherm,thermodynamic and kinetic studies

In the present study, hexagonal mesoporous silica (HMS) was synthesized and modified by tannic acid as a natural poly-phenol and amine (TA-A-HMS) and was applied for the adsorption of bovine serum albumin (BSA) from aqueous media. To investigate the structure of HMS and TA-A-HMS, SEM, TEM, XRD, BET and FTIR analysis were applied. The effects of pH, adsorbent dosage, contact time and temperature on the BSA adsorption were studied. After modification, BET surface area of HMS was reduced from 885?m²/g to 51?m²/g which confirms the presence of tannin and amine groups that inhibit the adsorption of nitrogen molecules. According to the results of equilibrium data, it is shown that Langmuir isotherm with maximum adsorption capacity of 1000?mg/g is the predominant model and adsorption is mono-layer. Kinetic and thermodynamic studies also reveal that adsorption kinetic followed by pseudo-second order model and the adsorption process is exothermic.     

Deposition of α-SiΜο12Ο40-[Ru(bipyridine)(terpyridine)Cl] multilayer film on single wall carbon nanotube modified glassy carbon electrode: Improvement of the electrochemical properties and chemical stability

A simple procedure was developed for the preparation of glassy carbon electrodes modified with single wall carbon nanotubes (SWCNTs) and multilayers of SiΜο₁₂Ο₄₀⁴⁻-[Ru(bpy)(tpy)Cl]⁺(byp; bipyridine, tpy; terpyridine). Layer-by-layer deposition technique was used for the multilayer formation of SiΜο₁₂Ο₄₀⁴⁻-[Ru(bpy)(tpy)Cl]⁺ onto SWCNTs films. Based on the strong electrostatic attraction of oppositely charged species a Ru-complex/poly oxometalate hybrid film strongly and irreversibly adsorbed on the glassy carbon electrode modified with single walled carbon nanotubes. The multilayer assembly exhibited good stability and excellent electrochemical reversibility for both redox systems in the pH range1-7. It was found that up to fifteen monolayers could be deposited onto a carbon nanotube film with well defined redox behavior. The modified electrode shows excellent electrocatalytic activity towards sulfite oxidation. Due to synergistic effect between SWCNTs and oppositely charged species the repeated alternate adsorption of anions and cations by this simple dipping method leads to molecular sandwiches with interesting redox activity and remarkable stability.     

Flow resistance in a compound gravel-bed bend

In this paper, the effect of a gravel-bed in a compound bend (similar to sinusoidal top view) of a natural river (Zayandehrud River flowing through Isfahan, Iran) has been investigated for flow resistance analysis, measuring the velocity with a micro current meter. The data were analysed and the following observations were made. In a compound bend, the law of the wall can be valid for up to 66% of the flow depth from the bed. The parabolic law is the most effective method for the determination of shear velocity. Based on the existing criteria for verifying the equilibrium boundary layer, the flow cannot be in equilibrium. The shear stress distribution and the sediment transport parameters have considerable influence on resistance to flow. Froude number and the flow depth relative to the representative gravel size have little effect on the flow resistance estimation.     

In situ synthesis of hydroxyapatite-grafted titanium nanotube composite

ABSTRACT

The present study is an investigation to demonstrate the effectiveness of in situ approach in the synthesis of hydroxyapatite-grafted titanium nanotube composite (HA-TNT). This method involves combining the process of HA sol–gel and rapid breakdown anodisation of titanium in a novel solution consisting of NaCl and N₃PO₄. This new synthesis approach produced a uniform dispersion of Anatase and Rutile phases of TiO₂ nanotubes with minimal agglomeration in the matrix of crystalline HA. The characterisation of homogenised HA-TNT composite was investigated via field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM) and X-ray diffraction (XRD). FESEM and TEM images indicated the nanostructure of composite with TiO₂ nanotube diameter of approximately 10 nm. XRD and EDS analyses confirmed the formation of HA crystalline with the Ca/P ratio of 1.58 and formation of Anatase and Rutile phase of TiO₂ nanotubes.     

Two-parameter TSCSP method for solving complex symmetric system of linear equations

We introduce a two-parameter version of the two-step scale-splitting iteration method, called TTSCSP, for solving a broad class of complex symmetric system of linear equations. We present some conditions for the convergence of the method. An upper bound for the spectral radius of the method is presented and optimal parameters which minimize this bound are given. Inexact version of the TTSCSP iteration method (ITTSCSP) is also presented. Some numerical experiments are reported to verify the effectiveness of the TTSCSP iteration method and the numerical results are compared with those of the TSCSP, the SCSP and the PMHSS iteration methods. Numerical comparison of the ITTSCSP method with the inexact version of TSCSP, SCSP and PMHSS are presented. We also compare the numerical results of the BiCGSTAB method in conjunction with the TTSCSP and the ILU preconditioners.