Influence of Microalloying and Isothermal Treatment on Microstructure and Mechanical Properties of High Carbon Steel

Indrajit Dey,Rajib Saha,Swarup Kumar Ghosh 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The influence of isothermal holding (IH) near the pearlite start temperature (Ps≈610 °C) and above the martensite starttemperature (Ms≈245 °C) were studied in two hot-rolled (FRT≈1000 °C) high carbon steels, without (HC0) and with Nbmicroalloying (HC1). Optical microscopy (OM), field emission scanning electron microscopy (FESEM) and high-resolutiontransmission electron microscopy (HRTEM) were utilised for observing the microstructural constituents whereas, nanoindentationand microindentation were performed to estimate the average hardness and elastic modulus values of various phaseconstituents. It has been observed that hot deformation in the austenite region results in the formation of a dual phase-typemicrostructure consisting of fine pearlite lamella and ferrite grains with some amount of degenerated pearlite. IH at 570 °Cleads to a higher volume percentage of ferrite and coarsening of pearlite whereas, IH at 300 °C results in mixed phases comprisingbainite, a very low amount of martensite/retained austenite (M/RA), pearlite and some amount of ferrite. Hot rolledmicroalloyed steel when isothermally held near the Psresults in a significant enhancement of ductility than hot rolled andair-cooled condition while sacrificing tensile strength marginally, which may be attributed to a higher percentage of ferriteand refinement of pearlite due to Nb addition. The estimated yield strength values correlate well with those experimentalyield strength values, but a little discrepancy has been noticed for the ultimate tensile strength values. Possible interpretationsare suggested in this paper.

Maximum Scour Depth at Piers in Armor-Beds

Rajkumar V. Raikar,Subhasish Dey 대한토목학회 2009 KSCE JOURNAL OF CIVIL ENGINEERING Vol.13 No.2

The paper presents a design method to determine the maximum equilibrium scour depth at piers embedded in a sand-bed overlain by a thin armor-layer of gravels using the experimental data of Dey and Raikar and those of Ettema. The proposed equation is in terms of empirical relationships, termed K-factors, which account for the effects of flow depth, pier shape, flow intensity, bed sediment size and armor gravel size on scour depth for individual cases of scour holes as identified by Dey and Raikar. These Kfactors are determined by fitting envelope curves to the experimental data. The estimated largest possible scour depths that can occur at circular and square piers with an armor-layer are 3.15 and 3.47 times the pier width, respectively. The paper presents a design method to determine the maximum equilibrium scour depth at piers embedded in a sand-bed overlain by a thin armor-layer of gravels using the experimental data of Dey and Raikar and those of Ettema. The proposed equation is in terms of empirical relationships, termed K-factors, which account for the effects of flow depth, pier shape, flow intensity, bed sediment size and armor gravel size on scour depth for individual cases of scour holes as identified by Dey and Raikar. These Kfactors are determined by fitting envelope curves to the experimental data. The estimated largest possible scour depths that can occur at circular and square piers with an armor-layer are 3.15 and 3.47 times the pier width, respectively.

Application of Multivariate Adaptive Regression Spline-Assisted Objective Function on Optimization of Heat Transfer Rate Around a Cylinder

Prasenjit Dey,Ajoy K. Das 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.6

The present study aims to predict the heat transfer characteristics around a square cylinderwith different corner radii using multivariate adaptive regression splines (MARS). Further, the MARS-generated objective function is optimized by particle swarm optimization. The data for the prediction are taken from the recently published article by thepresent authors [P. Dey, A. Sarkar, A.K. Das, Development of GEP and ANN model to predictthe unsteady forced convection over a cylinder, Neural Comput. Appl. (2015) 1-13]. Further,the MARS model is compared with artificial neural network and gene expression programming. It has been found that the MARS model is very efficient in predicting the heattransfer characteristics. It has also been found that MARS is more efficient than artificialneural network and gene expression programming in predicting the forced convectiondata, and also particle swarm optimization can efficiently optimize the heat transfer rate.

Anilinolysis of Diethyl Phosphinic Chloride in Acetonitrile

Dey, Nilay Kumar,Lee, Hai-Whang Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.5

Pyridinolysis of Diethyl Phosphinic Chloride in Acetonitrile

Dey, Nilay Kumar,Kim, Chan-Kyung,Lee, Hai-Whang Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.2

Parameter estimation of four-parameter viscoelastic Burger model by inverse analysis: case studies of four oil-refineries

Dey, Arindam,Basudhar, Prabir Kr. Techno-Press 2012 Interaction and multiscale mechanics Vol.5 No.3

This paper reports the development of a generalized inverse analysis formulation for the parameter estimation of four-parameter Burger model. The analysis is carried out by formulating the problem as a mathematical programming formulation in terms of identification of the design vector, the objective function and the design constraints. Thereafter, the formulated constrained nonlinear multivariable problem is solved with the aid of fmincon: an in-built constrained optimization solver module available in MatLab. In order to gain experience, a synthetic case-study is considered wherein key issues such as the determination and setting up of variable bounds, global optimality of the solution and minimum number of data-points required for prediction of parameters is addressed. The results reveal that the developed technique is quite efficient in predicting the model parameters. The best result is obtained when the design variables are subjected to a lower bound without any upper bound. Global optimality of the solution is achieved using the developed technique. A minimum of 4-5 randomly selected data-points are required to achieve the optimal solution. The above technique has also been adopted for real-time settlement of four oil refineries with encouraging results.

A bioassay system for pharmacological standardization of Withania somnifera derived herbal remedies

Dey, Amitabha,Chatterjee, Shyam Sunder,Kumar, Vikas Cellmed Orthocellular Medicine and Pharmaceutical 2019 셀메드 (CellMed) Vol.9 No.1

Background: Contents of bioactive substances extractable from different parts of terrestrial plants vary enormously. Aim: To ascertain that parts of Withania somnifera other than its roots can also be used for prevention and cure of unavoidable stress triggered central hypersensitivity to pain. Material and Methods: Groups of male or female mice treated either with Withania somnifera extracts or with metformin, aspirin, imipramine, diazepam and niacin for 11 consecutive days were subjected to "foot-shock stress-induced hyperthermia" and "hot plate" tests on the 1st, 5th, 7th, and 10th days of the experiments. On the 11th day, they were subjected to tail suspension test and on 12th day pentobarbital hypnosis test. Results: Except for diazepam and imipramine, protective effects of all other tested drugs as well as of the Withania somnifera extracts against stress-induced central hypersensitivity to pain were accompanied by their preventive effects against foot-shock stress-induced body weight losses. All observed stress response suppressing effects of all test agents increased with increasing numbers of treatment days. However, mean duration of pentobarbital-induced sleep was shorter in the extracts treated groups and longer in the diazepam treated ones only. Conclusions: Reported observations reveal that pharmacological activity profile of Withania somnifera extracts in male and female mice are almost identical, and are not like those of several drugs currently often prescribed for the treatment of diabetes-associated comorbidities. Withanolides are not the only extractable bioactive constituents of Withania somnifera. The described bioassay system is well suited for pharmacological standardization of diverse types of Withania somnifera extracts.

Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction γ p → φ p (31 pages)

Dey, B.,Collaboration, CLAS THE AMERICAN PHYSICAL SOCIETY 2014 PHYSICAL REVIEW C - Vol.89 No.5

High-statistics measurements of differential cross sections and spin density matrix elements for the reaction gamma p -> phi p have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (v s) from 1.97 to 2.84 GeV, with an extensive coverage in the phi production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the f natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged-(phi -> K+ K-) and neutral( phi ->(KsKL0)-K-0) K (K) over bar decay modes of the phi Further, for the charged mode, we differentiate between the cases where the final K-track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed f mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide root s bins for the charged-and the neutral-modes, respectively. Possible effects from K+Lambda* channels with pK (K) over bar final states are discussed. These present results constitute the most precise and extensive phi photoproduction measurements to date and in conjunction with the omega photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.

Kinetics and mechanism of the aminolysis of dimethyl and methyl phenyl phosphinic chlorides with anilines

Dey, Nilay Kumar,Hoque, Md. Ehtesham Ul,Kim, Chan Kyung,Lee, Bon-Su,Lee, Hai Whang John Wiley Sons, Ltd. 2009 Journal of physical organic chemistry Vol.22 No.5

<P>The reactions of dimethyl phosphinic chloride (1) and methyl phenyl phosphinic chloride (2) with X-anilines have been studied kinetically in acetonitrile at 15.0 and 55.0 °C, respectively. The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC<SUB>6</SUB>H<SUB>4</SUB>ND<SUB>2</SUB>) are also reported for the same reactions. The obtained KIEs for 1 are secondary inverse (k<SUB>H</SUB>/k<SUB>D</SUB> = 0.703–0.899 < 1), while those for 2 are primary normal (k<SUB>H</SUB>/k<SUB>D</SUB> = 1.62–2.10 > 1). A concerted mechanism involving predominantly backside nucleophilic attack is proposed for the anilinolysis of 1. A concerted mechanism involving predominantly frontside attack via a hydrogen-bonded four-center-type transition state is proposed for the anilinolysis of 2. The degree of steric hindrance is the major factor that determines both the reactivity of the phosphinates and the direction of the nucleophilic attack on the phosphinates. Copyright © 2008 John Wiley & Sons, Ltd.</P> <B>Graphic Abstract</B> <P>Phosphoryl transfer reactions are known to proceed via two main types of mechanisms: a stepwise mechanism involving a trigonal bipyramidal pentacoordinate (TBP-5C) intermediate and a concerted mechanism via a single TBP-5C transition state (TS). When the nucleophile attacks the reaction center from the side opposite the leaving group (backside attack), the configuration is inversed. However, when the nucleophile attacks from the leaving group side (frontside attack), the configuration is retained. <img src='wiley_img/08943230-2009-22-5-POC1478-gra001.gif' alt='wiley_img/08943230-2009-22-5-POC1478-gra001'> </P>

Influence of an Anaerobic Fungal Culture (Orpinomyces sp.) Administration on Growth Rate, Ruminal Fermentation and Nutrient Digestion in Calves

Dey, Avijit,Sehgal, Jatinder Paul,Puniya, Anil Kumar,Singh, Kishan Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.6

The study was to see the effect of administration of ruminal fungi on feed intake, growth rate, rumen fermentation and nutrient digestion of calves (Tharparkar$\times$Holstein-Friesian, average age: 10 months, average body weight: 130 kg). The 6 calves in first group were fed a mixture consisted of 50% wheat straw and 50% concentrate (Maize 62%, Groundnut cake 35%, Mineral mix. 2% and Common salt 1%) along with 1 kg green oats $animal^{-1}$ $day^{-1}$ while second group calves were fed the above-mentioned diet in addition to a dose of 160 ml ($10^{6}$ CFU/ml) fungal culture $calf^{-1}$ $week^{-1}$. The average dry matter intake per day was slightly lowered in fungal fed calves yet feed conversion ratio was higher. The average daily weight gain was significantly higher (15.37%) in fungal administered group as compared to control. The nutrient digestibility was increased for crude fibre, NDF and ADF with fungal administration. Digestible energy value of straw-based diet in terms of percent TDN also increased. The pH and $NH_{3}$-N were lower whereas TVFA, total-N, TCA-N and number of zoospores were higher in rumen liquor in fungal administered group.