T. Deepan Bharathi Kannan, B. Suresh Kumar, G. Rajesh Kannan, M. Umar and Mohammad Chand Khan
This work is aimed at developing relations between the pertinent variables that affect drilling process of stainless steel using artificial neural network. The experiments were conducted on vertical CNC machining centre. The parameters used were spindle speed and feed rate. The effect of machining parameters on entry burr height, exit burr height and surface roughness was experimentally evaluated for different spindle speeds and feed rates. A model was established between the drilling parameters and experimentally obtained data using ANN. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the burr height and surface roughness in drilling of stainless steel. Genetic algorithm (GA) technique was used in this work to identify the optimized drilling parameters. Confirmation test was conducted with the optimized parameters and it was found that confirmation test results were similar to that of GA-predicted output values.
Nasar Ahmed, Abdul Majid, M.A. Khan, M. Rashid, Z.A. Umar and M.A. Baig
Self-assembled Zn/ZnO microspheres have been accomplished on selected sites of boron doped P-type silicon substrates using hydrothermal approach. The high density Zn/ZnO microspheres were grown on the Si substrates by chemical treatment in mixed solution of zinc sulfate ZnSO4·7H2O and ammonium hydroxide NH4(OH) after uniform heating at 95 °C for 15 min. The Zn/ZnO microspheres had dimensions in the range of 1 μm to 20 μm and were created only on selected sites of silicon substrate. The crystal structure, chemical composition and morphology of as-prepared samples were studied by using scanning electron microscope SEM, X-ray diffraction XRD, energy dispersive X-ray spectroscopy EDS, Fourier transform infrared spectroscopy FT-IR and UV-Vis diffuse reflectance absorption spectra DRS. The energy band gap Eg of about 3.28 eV was obtained using Tauc plot. In summary, this study suggests that interfacial chemistry is responsible for the crystal growth on indented sites of silicon substrate and the hydrothermal based growth mechanism is proposed as a useful methodology for the formation of highly crystalline three dimensional (3-D) Zn/ZnO microspheres.
Ahmad Nawaz, Bilal Islam, M. Zafar Ijaz, Umar Saleem, M. Sadiq Khattak, Shahid Nisar Ahmad, Nabeel Maqsood and Liaquat Ali
We propose an indirect method of ASTM D-1200 for measurement of viscosity from 0.1 to 30 stokes (St) using Ford cup 5 (range 2~ 12 St) by developing a statistical relation. General purpose low styrene content polyester resin (without adding initiator, hardener and accelerator) was used for viscosity measurement. In existing ASTM D 1200 standard, ford cups (1-4) are used to measure the viscosity up to 2 St, while fifth cup is used for measurement from 2 to 12 St. Viscosity above 12 St is not estimated using existing ASTM D- 1200 method. In contrast, our method and statistical relation proposed in this paper estimates viscosity in the flexible range of 0.1 to 30 St by using Ford cup 5 only. The estimated values were confirmed by existing ASTM D-1200 (0.1 to 12 St) and by using Ubbelohde viscometer (12 to 30 St). Values estimated above 12 St are from the proposed model are also in good conformance (percentage error ~ 5% or less) with experimental results. The satisfaction level of the estimated values with the experiments suggests that the model has also the potential for application to paints, polymer and oil industry.