Estimation of cutting forces and surface roughness for hard turning using neural networks

Metal cutting mechanics is quite complicated and it is very difficult to develop a comprehensive model which involves all cutting parameters affecting machining variables. In this study, machining variables such as cutting forces and surface roughness are measured during turning at different cutting parameters such as approaching angle, speed, feed and depth of cut. The data obtained by experimentation is analyzed and used to construct model using neural networks. The model obtained is then tested with the experimental data and results are indicated.     

Silver nanorods induced oxidative stress and chromosomal aberrations in the Allium cepa model

The production of different size and shape silver nanoparticles (AgNPs) has increased considerably in recent years due to several commercial and biological applications. Here, rod‐shaped AgNPs (SNRs) were prepared using the microwave‐assisted method and characterised by ultraviolet–visible spectroscopy, and transmission electron microscopy analysis. The present study aims to investigate the cyto–genotoxic effect of various concentrations (5, 10, and 15 µM) of SNRs using Allium cepa model. As a result, concentration‐dependent cyto–genotoxic effect of SNRs was observed through a decrease in the mitotic index, and an increase in the chromosomal aberrations such as chromosome break, disturbed metaphase, and anaphase bridge. To check the impact of Ag⁺ ions, 15 µM silver nitrate (AgNO₃) was prepared and tested in all the assays. Furthermore, cell viability and different reactive oxygen species assays were performed to test the cytotoxicity evaluation of SNRs. The authors found that in all the tested assays, SNRs at high concentrations (15 µM) and AgNO₃ (15 µM) were observed to cause maximal damage to the roots. Therefore, the current study implies that the cytotoxicity and genotoxicity of SNRs were dependent on the concentration of SNRs.Inspec keywords: ultraviolet spectra, biomedical materials, silver, cellular biophysics, nanorods, toxicology, visible spectra, nanoparticles, nanofabrication, transmission electron microscopy, nanomedicine, aberrations, microwave materials processingOther keywords: biological applications, rod‐shaped AgNPs, microwave‐assisted method, ultraviolet‐visible spectroscopy, transmission electron microscopy, chromosomal aberrations, chromosome break, silver nitrate, reactive oxygen species assays, cytotoxicity, genotoxicity, silver nanorods, oxidative stress, shape silver nanoparticles, concentration‐dependent cyto‐genotoxic effect, Allium cepa model, mitotic index, disturbed metaphase, anaphase bridge, cell viability, cytotoxicity evaluation, Ag     

Optical and electrical properties of hybrid photovoltaic devices from poly (3-phenyl hydrazone thiophene) (PPHT) and TiO2 blend films

Bulk heterojunction photovoltaic devices based on blends of a conjugated polymer poly (3-phenyl hydrazone thiophene) (PPHT) as electron donor and titanium dioxide (TiO₂) particles as an electron acceptor (n-type wide band gap semiconductor) have been studied. The blend films were spin coated from a common solvent mixture. The absorption peak and shape of the absorption spectra of PPHT:TiO₂ (40 vol%) indicate that it is a superposition of the absorption of PPHT and TiO₂. From the cyclic voltammetry measurements, we have estimated the values of levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) for PPHT. A strong fluorescence quenching indicates that the exciton dissociation and charge separation occurs successfully at PPHT:TiO₂ interfaces formed in the bulk. This also enhances the possibility that the separated charges will reach the electrodes before recombining. Experimentally observed current–voltage characteristics of this device has been explained employing the metal–insulator–metal (MIM) model, where the intimate mixture of electron accepting and hole accepting materials is treated as a homogeneous intrinsic semiconductor. In this device, holes are solely transported along the pure donor phase and electrons transported along the paths of acceptor phase. Effect of TiO₂ concentrations in the blend and thermal annealing of device has been described is detail. For low concentration of TiO₂ below 20% the device performance is poor than that for pure PPHT, while for higher concentration of TiO₂ significant improvement was obtained. The thermal annealing of the device also improves the photovoltaic response of the device, which may be due to the reduction in the recombination process.     

Preparation of a Porous Cermet SOFC Anode Substrate by Gelcasting of NiO–YSZ Powders

A porous NiO–YSZ substrate for anode-supported solid oxide fuel cells has been prepared by gelcasting of NiO–YSZ powders using urea–formaldehyde monomers, followed by humidity-controlled drying, binder removal, and sintering of the gelled bodies. The gelled bodies had sufficient strength to remove even 2-mm-thick samples from the mold immediately after gelation. A gelcast NiO–YSZ sample sintered at 1450°C for 2 h showed an open porosity of ∼53 vol%, and the porosity increased to ∼58% upon reduction with hydrogen. Pore sizes measured on the scanning electron microscopy photomicrograph of NiO–YSZ and Ni–YSZ cermet substrates are in the range of 2–5 μm. Urea–formaldehyde polymer, present in a high amount (∼13 wt%) in the gelcast body, acts as a template for pores.     

Free vibration studies on typical large flexible spacecraft appendages under vacuum conditions

This paper deals with theoretical and experimental investigations on the free vibration characteristics of representative large flexible solar array appendages used in spacecrafts under vacuum environmental conditions prevailing in space. Eight different configurations of solar panels with varied flexibility and surface area have been studied. The theoretical results, namely the modal parameters, have been correlated with results from experiments. These are performed on solar arrays of different configurations under varied parameters of panel flexibility, vacuum and amplitudes of vibration.     

Characterization and sintering of BaZrO3 nanoparticles synthesized through a single-step combustion process

Barium zirconate (BaZrO₃) nanoparticles synthesized by a self-sustained single-step combustion process is reported in this paper. In this process, a phase pure nanopowder of BaZrO₃ has been obtained by the combustion of an aqueous solution containing Ba and Zr ions by using citric acid as complexing agent and liquor ammonia as fuel, thus giving rise to phase pure BaZrO₃ nanopowder in a single-step combustion without any further calcination. The X-ray diffraction studies have shown that the as-prepared powder was single phase, crystalline, and has a cubic perovskite structure (ABO₃) with a lattice constant a = 4.19 Å. The average particle size calculated from FWHM is 30 nm. The phase purity of BaZrO₃ nanopowder has been examined using differential thermal analysis (DTA), thermo gravimetric analysis (TGA) and Fourier transform of infrared spectroscopy (FTIR). The transmission electron microscopic investigation has shown that the particle size of the as-prepared powder was in the range 30–50 nm with a mean size of 40 nm. The nano BaZrO₃ has been sintered to a density of 99% of the theoretical density at 1650 °C in 2 h without the use of any sintering aids. The morphology of the sintered pellets has been studied with scanning electron microscopy (SEM). The dielectric constant (_r) and loss factor (tan δ) values obtained at 10 MHz for a well-sintered barium zirconate pellet has been found to be 32.2 and 1 × 10⁻⁴, respectively, at room temperature.     

Effect of immobile water content on contaminant transport in unsaturated zone

The effect of immobile water content on contaminant advection and dispersion in unsaturated porous media has been studied using a formulation which assumes that even in the immobile liquid zone, there occurs minor liquid flow. An approach is proposed for computing this liquid velocity. One dimensional numerical simulation is carried out to study the effect of immobile water content on the time of appearance of contaminant at the bottom of an unsaturated column. The numerical model developed is verified using analytical solutions for simple advective-dispersive cases. From the simulations, it was observed that increase in the immobile water content leads to quicker appearance of contaminant.     

Use of micelles in photogalvanic cell for solar energy conversion and storage: Azur A-glucose system

Sodium lauryl sulphate (NaLS), tetradecyl trimethyl ammonium bromide (TTAB) and Brij-35 were used in a photogalvanic cell containing azur A as a photosensitizer and glucose as a reductant for solar energy conversion and storage. The photopotential and photocurrent generated by the cell in the presence of NaLS were 811.0 mV and 1470 μA, respectively. The effect of variation of the concentrations of the surfactants on the electrical output, the fill factor, the conversion efficiency and the performance of the cell in the dark was studied in detail.