Arc characterization study for submerged arc welding of HSLA (API X80) steel

Journal of Mechanical Science and Technology - The load bearing capacity of weld is highly influenced by the mode of metal transfer which in turn is dependent on welding current and arc voltage....     

Influence of annealing on p-type Cu2ZnSnS4 thin film by dip coating solution growth technique for the application of solar cell

Thin films of Cu₂ZnSnS₄ have been deposited by solution growth dip coating method. Different Cu/Zn/Sn/S molar ratios were applied, which tells the properties of copper, Zinc, Tin, and Sulfide using X-ray diffraction, UV–vis, Energy dispersive X-ray spectroscopy, and scanning electron spectroscopy. The pure CZTS thin film showed the phase transformation from Kesterite (tetragonal) to Kesterite (orthorhombic) crystal structure. Optical measurement analysis reveals that layers have relatively high absorption coefficient in the visible spectrum with a band gap reduction of 1.51–1.49?eV with an increase in the annealing temperature from room temperature to 300?°C for 1?h in hot air furnace without any presence of an inert gas. Optical conductivity was observed to increase from 10¹² to 10¹³ (sec)^?1 and electrical conductivity was of the order of 10² (Ω?cm)^?1.     

Electroanalytical studies on cadmium(II) selective potentiometric sensors based on t-butyl thiacalix[4]arene and thiacalix[4]arene in poly(vinyl chloride)

Cd²⁺-selective sensors have been fabricated from poly(vinyl chloride) (PVC) matrix membranes containing t-butyl thiacalix[4]arene (I) and thiacalix[4]arene (II) as electroactive materials. The addition of sodium tetraphenylborate and the plasticizer 2-nitrophenyl octyl ether has been found to improve the performance of the sensors substantially. The membranes of various compositions of the two thiacalixarenes have been investigated and it was found that the best performance was obtained for the membrane of composition II:PVC:NaTPB:NPOE in the ratio 5:120:3:150. The sensor shows a linear potential response for Cd²⁺ over a wide activity range 3.2 × 10⁻⁶ to 1.0 × 10⁻¹ M with Nernstian compliance (29.5 mV decade⁻¹ of activity) in pH range 4.5-6.5 and a fast response time of ∼8 s. The potentiometric selectivity coefficient values determined by matched potential method indicate excellent selectivity for Cd²⁺ ions over mono-, di- and trivalent interfering cations. The sensor exhibits adequate shelf life (∼3 months) with good reproducibility (S.D. ±0.2 mV) and can also be used in partially non-aqueous media having up to 20% (v/v) methanol, ethanol or acetone content with no significant change in the value of slope or working activity range. The sensor has been used in the potentiometric titration of Cd²⁺ with EDTA. The sensor could be successfully used for the quantification of cadmium in river water samples.     

Multi-objective optimization of electric-discharge machining process using controlled elitist NSGA-II

Parametric optimization of electric discharge machining (EDM) process is a multi-objective optimization task. In general, no single combination of input parameters can provide the best cutting speed and the best surface finish simultaneously. Genetic algorithm has been proven as one of the most popular multi-objective optimization techniques for the parametric optimization of EDM process. In this work, controlled elitist non-dominated sorting genetic algorithm has been used to optimize the process. Experiments have been carried out on die-sinking EDM by taking Inconel 718 as work piece and copper as tool electrode. Artificial neural network (ANN) with back propagation algorithm has been used to model EDM process. ANN has been trained with the experimental data set. Controlled elitist non-dominated sorting genetic algorithm has been employed in the trained network and a set of pareto-optimal solutions is obtained.

     

Natural circulation studies in a lead bismuth eutectic loop

Lead Bismuth Eutectic (LBE) is increasingly getting more attraction as the coolant for advanced reactor systems. It is also the primary coolant of the Compact High Temperature Reactor (CHTR), being designed at BARC. A loop has been set up for thermal hydraulics, instrument development and material related studies relevant to CHTR. Steady state natural circulation experimental studies were carried out for different power levels. Transient studies for start-up of natural circulation in the loop, loss of heat sink and step power change have also been carried out. An 1D code named LeBENC has been developed at BARC to simulate the natural circulation characteristics in closed loops. The salient features of the code include ability to handle non-uniform diameter components, axial thermal conduction in fluid and heat losses from the piping to the environment. This paper deals with the experimental studies carried out in the loop. Detailed validation of the LeBENC code with the experimental data is also discussed in the paper.     

Simple first-order translinear-C current-mode all-pass sections

A first-order translinear-C current-mode (CM) all-pass section (APS) using two current-controlled conveyors (CCCII) and a single capacitor is given. A canonical CM-APS using only one dual-output CCCII and one capacitor is also derived from the proposed configuration. The circuits are analysed for the non-idealities of CCCII and possess attractive sensitivity performance. The proposed circuits are electronically tunable over a wide frequency range. RSPICE simulation results for ac analysis, transient analysis and harmonic distortions are incorporated to verify the theory.     

Issues and strategies in composite fabrication via friction stir processing: A review

Friction stir processing (FSP) is an expeditiously emerging novel technique involving exterior layer modification, which enables one to successfully fabricate surface composites (SCs) as well as bulk composites of the metal matrix. SCs constitute an exclusive class of composites which exhibit improved surface properties while retaining the bulk properties unaltered. During initiative years, FSP was employed in development of SCs of light metal alloys like aluminum. But, nowadays, it has gained a shining role in the field of SC fabrication of various nonferrous alloys like aluminum, magnesium, copper, and even ferrous metals like steel etc. This article reviews the current trends, various issues, and strategies used to enhance the efficiency of the fabrication process of SCs. Factors involved in the process of SC fabrication are discussed and classified with a new approach. Also, variation of microstructural and mechanical characteristics with these factors is reviewed. In addition to a brief presentation on the interaction between various inputs and their effects on properties, a summary of literature on SC fabrication for different metals is tabulated with prominent results. Subsequently, shortfalls and future perspectives of FSP on SC fabrication domain are discussed.     

Polyelectrolyte mediated scalable synthesis of highly stable silver nanocubes in less than a minute using microwave irradiation

Silver nanocubes were synthesized for the first time in large quantities on gold seed in the presence of a polyelectrolyte using microwave heating for 60-120?s. Our experiment indicates that the polyelectrolyte directs the growth of the particle in a specified crystallographic direction resulting in the faceted particle, i.e.?a nanocube. The nanocubes are stable for at least 2 months in ambient conditions.     

A Light Harvesting,Self‐Powered Monolith Tactile Sensor Based on Electric Field Induced Effects in MAPbI3 Perovskite

Organolead trihalide perovskite MAPbI₃ shows a distinctive combination of properties such as being ferroelectric and semiconducting, with ion migration effects under poling by electric fields. The combination of its ferroelectric and semiconducting nature is used to make a light harvesting, self‐powered tactile sensor. This sensor interfaces ZnO nanosheets as a pressure‐sensitive drain on the MAPbI₃ film and once poled is operational for at least 72 h with just light illumination. The sensor is monolithic in structure, has linear response till 76 kPa, and is able to operate continuously as the energy harvesting mechanism is decoupled from its pressure sensing mechanism. It has a sensitivity of 0.57 kPa^?1, which can be modulated by the strength of the poling field. The understanding of these effects in perovskite materials and their application in power source free devices are of significance to a wide array of fields where these materials are being researched and applied.     

Investigation on condensation in presence of a noncondensable gas for a wide range of Reynolds number

A theoretical model has been developed to study the local heat transfer coefficient of a condensing vapour in the presence of a noncondensable gas, where the gas/vapour mixture is flowing downward inside a vertical tube. The two-phase heat transfer is analysed using an annular flow pattern with a liquid film at the tube wall and a turbulent gas/vapour core. The gas/vapour core is modeled using the analogy between heat and mass transfer. The model incorporates Nusselt equation with McAdams modifier and Blangetti model for calculating the film heat transfer coefficient, Moody and Wallis correlations to account for film waviness effect on gas/vapour boundary layer. The suction effect due to condensation, developing flow and property variation of the gas phase is also considered. A comparative study of heat transfer coefficient and vapour mass flow rate has been made with various models to account for condensate film resistance and condensate film roughness. Results show that for very high Reynolds number, the condensation heat transfer coefficient is higher than the film heat transfer coefficient.