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Sintered eutectoid P/M steel behaviour during cold upsetting
(ABM, ABC, ABPol, 2008-01-03) Kannan, A. Rajesh; Pandey, K.S.; Shanmugam, S; Narayanasamy, R
Cold upsetting experiments were carried out on sintered Fe-0.8%C steel preforms in order to evaluate the technical relationship that exist between the applied stresses against continuous deformation and densification. Powder preforms of 86% theoretical density and 0.40 of initial aspect ratio were subjected to incremental compressive loading of 0.04 MN under three different friction conditions such as dry, graphite and zinc stearate employed during deformation until fracture appears at free surfaces. Experimental results revealed that the response of applied stresses with induced strain and attained densification exhibits a continuous enhancement but with three different stages. Irrespective of friction conditions the first and third stage shows steep rise. which offers high resistance to deformation, whereas the second stage shows virtually steady state; deformation needed gradual increase in applied stresses but with high rate of densification. Further. preform deformed under without lubricant exhibited maximum strain hardening as well as an enhanced rate of strain hardening through out the deformation in comparison with lubricants employed conditions.
5,7-Bis(benz-yloxy)-2-phenyl-4H-chromen-4-one
(International Union of Crystallography, 2008-11-29) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Jaswant, Buckle; Sulochana, Nagarajan
In the title compound, C29H22O4, the chromene ring is almost planar with a small puckering [0.143 (2) Å]. The crystal structure is stabilized by C - H⋯O and C - H⋯π inter-actions. Edge-to-face (centroid-centroid distances of 3.894 and 3.673 Å) and face-to-face (centroid-centroid distance of 3.460 Å) π-π-ring electron inter-actions are also observed. © 2008.
2-Phenyl-5,7-bis(prop-2-en-1-yloxy)-4H-chromen-4-one
(International Union of Crystallography, 2008-12-03) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
In the title compound, C21H18O4, tthe dihedral angle between the chromene ring system and the pendant phenyl ring is 6.1 (1)°. The crystal structure is stabilized by an intermolecular C - H⋯O and C - H⋯π inter-actions.
Dimethyl 2,2′-[(4-oxo-2-phenyl-4H-chromene-5,7-diyl)dioxy]diacetate: A more densely packed polymorph
(International Union of Crystallography, 2009-01-14) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Jaswant, Buckle; Sulochana, Nagarajan
The title mol-ecule, C21H18O8, crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o314-o315]. The mol-ecules of both polymorphs differ by the conformation of the oxomethyl-acetate groups. The title mol-ecules are rather planar compared to the mol-ecules of the other polymorph. In the title mol-ecule, one of the oxomethyl-acetate groups is disordered (occupancies of 0.6058/0.3942). The structures of both polymorphs are stabilized by C - H⋯O and C - H⋯π inter-actions. Due to the planarity of the title mol-ecules and similar inter-molecular inter-actions, the title mol-ecules are more densely packed than those of the other polymorph.
5,7-Dimeth-oxy-2-phenyl-4H-chromen-4-one
(International Union of Crystallography, 2009-02-11) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
The asymmetric unit of the title compound, C17H 14O4, contains two independent mol-ecules which differ in the relative orientations of the phenyl rings with repect to the essentially planar [maximum deviations of 0.029 (2) and 0.050 (2) Å in the two mol-ecules] chromene fused-ring system, forming dihedral angles of 10.3 (5) and 30.86 (5)° in the two mol-ecules. The crystal structure is stabilized by weak C - H⋯O and C - -H⋯π inter-actions, and π-π stacking inter-actions.
6,8-Dibromo-5-hydr-oxy-4-oxo-2-phenyl-4H-chromen-7-yl acetate
(International Union of Crystallography, 2009-02-21) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
In the title compound, C17H10Br2O5, the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) Å]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)°. The crystal structure is stabilized by intermolecular C - H⋯O inter-actions and an intramolecular O - H⋯O hydrogen bond also occurs.
Simulation of weld bead geometry in gta welded duplex stainless steel(DSS)
(John Wiley & Sons Ltd, 2009-07-22) Sathiya, P; Jinu, G.R.; Singh, Navjot
Temperature analysis of GTA welding of Duplex Stainless Steel material (2205) is simulated using ANSYS software by finite element technique taking in account the characteristics and advantage of GTAW than other sources. A travel heat source combined with body loads was designed by analyzing thermal physical parameters, latent heat of fusion of material. Modeling was carried out by using solid modeling and direct generation technique. A residual control method was taken for precise node selection, Simulation was done by varying the parameter of GTA, welding speed. The quasisteady state temperature field of GTA welding was simulated with the FEA softwareANSYS as well as tests. The objective of this work is to compare the experimentally obtained weld bead geometry of DSS material with simulated results from ANSYS software for various weld parameters. The higher the value of joining efficiency is, the less heat energy is spent on unnecessary heating-that is generating a heat affecting zone (HAZ) or distortion. Joining of two metals or alloys is important in every aspect of engineering which leads to welding in an effective manner and carrying out the analysis. The experimental analysis shows that the model is showing good agreement with the experimental results. Comparison of the experimental and simulated results shows the maximum deviation of 1.27 and 10 for calculating bead width and depth of penetration, respectively. Copyright © 2009 P. Sathiya et al.
An experimental study of thermal fatigue on ASTM A 213 grade T-23 steel tube
(Hindawi Limited, 2009-08-31) Jinu, G.R.; Sathiya, P; Ravichandran, G; Rathinam, A
Super heater tubes are subjected to alternate heating and cooling in power plants causes crack and eventually fail. This phenomenon is termed as thermal fatigue. In this paper, a laboratory simulation for reproducing thermal fatigue phenomenon is developed to determine the number of cycles of failure occurs in super heater tubes. Thermal fatigue tests are conducted in Non-Destructive Tested T23 base and SMAW welded tubes separately. The tubes are subjected to thermal cycles from 800∘C (accelerated temperature) to room temperature (28∘C). In this work 800∘C is selected in order to achieve the crack much earlier. The selected temperature is just below the Ac1 temperature. The tubes are subjected to heat by Oxy-acetylene flame and subsequently quenched with water. The tests are carried out until open cracks are identified. Surface cracks are identified in the base and weld tubes after 120 and 80 cycles respectively. The tubes are then sectioned and subjected to optical microscopy. The causes of failures are thoroughly investigated using Scanning Electron Microscope (SEM). This study reveals that localised heating and cooling causes thermal fatigue which initiates cracks in the tubes.
1-Benzoyl-3,3-bis(propan-2-yl)thiourea
(International Union of Crystallography, 2010-07-24) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
Two independent thiourea derivatives comprise the asymmetric unit of the title compound, C14H20N2OS. The major difference between the mol-ecules relates to a twist in the relative orientation of the benzene rings [torsion angles = 4.5 (2) and -19.9 (2)° for the two independent mol-ecules]. The thio-carbonyl and carbonyl groups lie to opposite sides of the mol-ecule as there are twists about the central N - S bond [torsion angles = 83.90 (15) and 81.77 (15)°]. Supra-molecular chains extending parallel to [101] with a stepped topology and mediated by N - H⋯O hydrogen bonding feature in the crystal structure. C - H⋯O and C - H⋯π inter-actions are also present.
Image Segmentation using Euler Graphs
(CCC Publications, 2010-09-01) Janakiraman, T.N.; Chandra Mouli, P.V.S.S.R.
This paper presents a new algorithm for image segmentation problem using the concepts of Euler graphs in graph theory. By treating image as an undirected weighted non-planar finite graph (G), image segmentation is handled as graph partitioning problem. The proposed method locates region boundaries or clusters and runs in polynomial time. Subjective comparison and objective evaluation shows the efficacy of the proposed approach in different image domains. © 2006-2010 by CCC Publications.
3-Benzoyl-1,1-dibenzylthiourea
(International Union of Crystallography, 2010-09-18) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
Two independent thio-urea molecules comprise the asymmetric unit of the title compound, C22H20N2OS. The central N-C(=S)N(H)C(=O) atoms in each molecule are virtually superimposable and each is twisted [C - N - C - S torsion angles = 121.3 (3) and -62.3 (4)°]. The molecules differ only in terms of the relative orientations of the benzyl benzene rings [major difference between the C - N - C - C torsion angles of -146.6 (3) and -132.9 (3)°]. The presence of N - H⋯S hydrogen bonding leads to the formation of supra-molecular chains along the a axis. These are consolidated in the crystal packing by C - H⋯O interactions. The crystal was found to be a combined non-merohedral and racemic twin (twin law 1̄00/01̄0/001), with the fractional contribution of the minor components being approximately 9 and 28%.
1-Benzoyl-3,3-dibutylthiourea
(International Union of Crystallography, 2010-09-25) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
The title molecule, C16H24N2OS, is twisted about the central N(H) - C bond with a C - N(H) - C - N torsion angle of -62.67 (15)°. The carbonyl group is twisted out of the plane of the benzene ring, forming a C - C - C=O torsion angle of -25.06 (17)°. In the crystal, molecules related by centres of symmetry are linked by pairs of inter-molecular N - H⋯S hydrogen bonds, forming eight-membered {⋯HNCS}2 synthons. These are further connected by weak via C - H⋯O contacts, forming a two-dimensional array in the bc plane.
1-Benzoyl-3,3-bis-(2-methylpropyl)thiourea
(International Union of Crystallography, 2011-02-12) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R.T.
The title compound, C16H24N2OS, is twisted about the central N(H) - C bond with the C - N - C - S torsion angle being 119.6 (3)°. The carbonyl O and thione S atoms are directed to opposite sides of the molecule, a conformation that allows for the formation of a linear supramolecular chain comprising alternating eight-membered {⋯HNCS} 2 and 14-membered {⋯HCNCNCO}2 synthons.
{4-Bromo-2-[(2-sulfidophenyl)iminomethyl]phenolato-k3 S,N,O}(triphenylphosphane-kP)nickel(II)
(International Union of Crystallography, 2011-03-12) Muthu Tamizh, M.; Karvembu, R; Varghese, B; Tiekink, Edward R. T.
The NiII atom in the title complex, [Ni(C13H 8BrNOS)(C18H15P)], is coordinated by the N, O and S atoms of he dianionic tridentate ligand, and its square-planar geometry is completed by a phosphane P atom. The dihedral angle between the aromatic rings in the 4-bromo-2-[(2-sulfidohenyl)imino-meth-yl]phenolate ligand is 2.01 (14)°. The most prominent feature of the packing is the presence of supramolecular chains aligned along the a axis, mediated by C - H⋯S interactions.
1-Benzoyl-3-methyl-3-pentylthiourea
(International Union of Crystallography, 2011-04-16) Gunasekaran, N; Jerome, P; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
Two independent molecules comprise the asymmetric unit of the title compound, C14H20N2OS. These differ in the relative orientations of the pentyl chains [C-C-C-C torsion angles = 176.7 (3) and 176.4 (3)°]. Significant twists are evident in each molecule, the dihedral angles formed between the thiourea and amide residues being 53.47 (17) and 55.81 (17)°. In the crystal, each molecule self-associates via a centrosymmetric eight-membered {⋯HNC S}2 synthon, and these are connected into a supramolecular chain along [110] via C-H⋯O contacts. Disorder is noted for one of the independent molecules in that two orientations (50:50) were resolved for its benzene ring.
Bis(3-benzoyl-1,1-disecbutyl-thioureato- 2 O,S)palladium(II)
(International Union of Crystallography, 2011-09-17) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
The complex molecule of the title complex, [Pd(C 16H 23N 2OS) 2], is completed by crystallographic twofold symmetry with the metal atom lying on the rotation axis. The Pd II atom exists within a slightly distorted squareplanar geometry defined by a cis-O 2S 2 donor set. The dihedral angle formed between the mean planes of the symmetry-related six-membered chelate rings is 12.88 (7)° and the bond lengths within the rings are indicative of significant electron delocalization. In the crystal, molecules aggregate into dimers linked by four C-H⋯O interactions.
Dicyclohexylammonium thiocyanate: Monoclinic polymorph
(International Union of Crystallography, 2011-10-05) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
The title salt, C12H24N+·NCS -, represents a monoclinic polymorph of the previously reported ortho-rhom-bic form [Khawar Rauf et al. (2008). Acta Cryst. E64, o366]. Two independent formula units comprise the asymmetric unit with the major difference in their mol-ecular structures relating to the relative dispositions of the cyclohexyl rings [dihedral angles = 79.88 (6) and 67.72 (5)°]. Further, the independent anions form distinctive patterns of hydrogen-bonding interactions, i.e. 2 × N - H⋯N versus N - H⋯N and N - H⋯S. The resulting supra-molecular architecture is a supra-molecular chain along the c axis based on a square-wave topology. © Selvakumaran et al. 2011.
Dibenzylazanium chloride
(International Union of Crystallography, 2012-02-04) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
In the title salt, C 14H 16N +·Cl -, the complete cation and complete anion are generated by the application of mirror symmetry. The molecule is nonplanar, as seen in the dihedral angle between the terminal phenyl rings [70.92 (5)°]. In the crystal, N - H⋯Cl hydrogen bonds involving both azanium H atoms link the ions into a zigzag supramolecular chain along [100].
Kinetics and equilibrium studies for the removal of heavy metals in both single and binary systems using hydroxyapatite
(Springer Verlag, 2012-03-21) Ramesh S.T.; Rameshbabu, N; Gandhimathi, R; Nidheesh, P.V.; Srikanth Kumar, M
Removal of heavy metals is very important with respect to environmental considerations. This study investigated the sorption of copper (Cu) and zinc (Zn) in single and binary aqueous systems onto laboratory prepared hydroxyapatite (HA) surfaces. Batch experiments were carried out using synthetic HA at 30 °C. Parameters that influence the adsorption such as contact time, adsorbent dosage and pH of solution were investigated. The maximum adsorption was found at contact time of 12 and 9 h, HA dosage of 0. 4 and 0. 7 g/l and pH of 6 and 8 for Cu and Zn, respectively, in single system. Adsorption kinetics data were analyzed using the pseudofirst-, pseudosecond-order and intraparticle diffusion models. The results indicated that the adsorption kinetic data were best described by pseudosecond-order model. Langmuir and Freundlich isotherm models were applied to analyze adsorption data, and Langmuir isotherm was found to be applicable to this adsorption system, in terms of relatively high regression values. The removal capacity of HA was found to be 125 mg of Cu/g, 30. 3 mg of Zn/g in single system and 50 mg of Cu/g, 15. 16 mg of Zn/g in binary system. The results indicated that the HA used in this work proved to be effective material for removing Cu and Zn from aqueous solutions. © 2012 The Author(s).
ANN model of RF MEMS lateral SPDT switches for millimeter wave applications
(PubMed ID, 2012-07-16) Suganthi, S; Murugesan, K; Ragavan, S
his paper presents Artificial Neural Network (ANN) implementation for the Radio Frequency (RF) and Mechanical modeling of lateral RF Micro Electro Mechanical System (MEMS) series micro machined Single pole double through (SPDT) switch. We propose an efficient approach based on ANN for analyzing the losses in ON and OFF state of lateral RF MEMS series switch by calculating the S-parameters. The double beam structure has been analyzed in terms of its return, isolation and insertion losses with the variation of its passive circuit component values. The effect of design parameters has been analyzed and the lateral switch was realized with low insertion loss, high return and isolation losses. ANN model were trained with five different training algorithms namely Levenberg-Marquart (LM), Bayesian Regularization (BR), Quasi - Newton (QN), Scaled Conjugate Gradient (SCG) and Conjugate Gradient of Fletcher - Powell (CGF) to obtain better performance and fast convergence. The results from the neural model trained by Levenberg-Marquardt back propagation algorithm are highly agreed with the theoretical results available in the literature. The neural networks shows the better results with the highest correlation coefficient which measures the strength and direction of linear relation between two variables (actual and predicted values) (0.9998) along with lowest root mean square error (MSE) of (0.0039).

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