Jadavpur University

About: Jadavpur University is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Population & Fuzzy logic. The organization has 10856 authors who have published 27678 publications receiving 422069 citations. The organization is also known as: JU & Jadabpur University.

Parametric analysis on electrochemical discharge machining of silicon nitride ceramics

Abstract: The electrochemical discharge machining (ECDM) process has a potential in the machining of silicon nitride ceramics. This paper describes the development of a second order, non-linear mathematical model for establishing the relationship among machining parameters, such as applied voltage, electrolyte concentration and inter-electrode gap, with the dominant machining process criteria, namely material removal rate (MRR), radial overcut (ROC) and thickness of heat affected zone (HAZ), during an ECDM operation on silicon nitride. The model is developed based on response surface methodology (RSM) using the relevant experimental data, which are obtained during an ECDM micro-drilling operation on silicon nitride ceramics. We also offer an analysis of variance (ANOVA) and a confirmation test to verify the fit and adequacy of the developed mathematical models. From the parametric analyses based on mathematical modelling, it can be recommended that applied voltage has more significant effects on MRR, ROC and HAZ thickness during ECDM micro-drilling operation as compared to other machining parameters such as electrolyte concentration and inter-electrode gap.

Unusual coordination mode of thiosemicarbazone ligands. A search for the origin.

Abstract: Twelve mixed-ligand thiosemicarbazone complexes of ruthenium and osmium, ten of general formula [M(bpy)2(bztsc-R)]ClO4, (M = Ru, Os; bpy = 2,2'-bipyridine, Hbztsc-R = benzaldehyde thiosemicacbazone) and two of type [M(bpy)2(actsc)]ClO4 (Hactsc = acetonethiosemicarbazone), have been synthesized and characterized. All the complexes are diamagnetic (low-spin d6, S = 0) and in acetonitrile solution show several intense metal-to-ligand charge-transfer (MLCT) transitions in the visible region. Structures of Hbztsc-OMe, [Ru(bpy)2(bztsc-NO2)]ClO4 and [Ru(bpy)2(actsc)]ClO4 have been determined by X-ray crystallography. Benzaldehyde thiosemicarbazone exists in the thione form with the phenyl group trans to the hydrazinic nitrogen. The benzaldehyde thiosemicarbazone ligand coordinates to the metals through the hydrazinic nitrogen and sulfur with a bite angle of approximately 67 degrees, forming a four-membered chelate ring. However, the actsc ligand coordinates through the imine nitrogen and sulfur, forming a five-membered chelate ring with a bite angle of approximately 81 degrees. The difference in coordination modes of two types of thiosemicarbazone ligands, viz., bztsc-R and actsc, appears to result from the difference in steric bulk of the aryl and methyl group trans to the hydrazinic nitrogen. In acetronitrile solution they all show a reversible metal(II)-metal(III) oxidation in the range 0.18-0.58 V vs SCE followed by an irreversible oxidation in the range 1.11-1.60 V vs SCE. Two successive one-electron reductions of the coordinated bipyridine are also observed in the range -1.53 to -1.96 V vs SCE.

Bee colony optimization for combined heat and power economic dispatch

Abstract: This paper presents a novel optimization approach to the combined heat and power economic dispatch problem by using bee colony optimization algorithm. The algorithm is a swarm-based algorithm inspired by the food foraging behavior of honey bees. The performance of the proposed algorithm is validated by illustration with a test system. The results of the proposed approach are compared with those of particle swarm optimization, real-coded genetic algorithm and evolutionary programing techniques. From numerical results, it is seen that bee colony optimization based approach is able to provide a better solution at a lesser computational effort.

The influence of hydrogen bonding on the dielectric constant and the piezoelectric energy harvesting performance of hydrated metal salt mediated PVDF films

Abstract: Polyvinylidene fluoride (PVDF) films are filled with various mass fractions (wt%) of hydrated metal salt (MgCl2·6H2O) (Mg-salt) to fabricate high performance piezoelectric energy harvesters (PEHs). They deliver up to 4 V of open circuit voltage by simply repeated human finger imparting (under a pressure of ∼4.45 kPa) and also generate sufficient power to turn on at least ten commercial blue light emitting diodes (LEDs) instantly. The enhanced piezo-response is attributed to the combined effect of the change in the inherent dipole moment of the electroactive phase containing PVDF itself and H-bonding arising between the Mg-salt filler and PVDF via electrostatic interactions. Furthermore, it also successfully charged the capacitors, signifying practical applicability as a piezoelectric based energy harvester power source. UV-visible optical absorption spectral analysis revealed the possibility to estimate a change in the optical band gap value at different concentrations of Mg-salt filler added PVDF films that possess a useful methodology where the Mg-salt can be used as an optical probe. In addition dielectric properties have been studied to understand the role of molecular kinetic and interfacial polarization occurs in H-bond PVDF films at different applied frequencies at room temperature.