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91.
A. Biswas R. Srinivasan P. Chellapandi S. C. Chetal 《Transactions of the Indian Institute of Metals》2010,63(2-3):653-656
In Prototype Fast Breeder Reactor, the core is immersed in a sodium pool contained within the main vessel (MV). There is an argon cover gas space over the sodium. Top Shield supports the control plug which houses important components such as Control and Safety Rod Driving Mechanism. A core support structure welded to the bottom of MV carries the Grid plate which in turn supports the fuel subassemblies. MV is a cylindrical shell with a bottom dished end and supported at the top. Double ended guillotine rupture of MV will lead to downward movement of the core, which is in effect equivalent to withdrawal of control and safety rod and thus causing a series safety concern. It is essential to demonstrate Leak Before Break (LBB) argument for MV. LBB argument is justified if leak detection is ensured with adequate margin on critical crack length corresponding to failure by tearing instability. The material of construction of MV is SS316 LN. Towards assuring the justification of LBB argument, an isolated 5 mm deep X 200 mm long semi elliptical flaw is taken as the initial flaw and analysed under fatigue loading. A through wall crack in the argon space can be detected by sampling the nitrogen in the annular space between MV and safety vessel surrounding it. Accordingly the detectable crack length is arrived at. The critical crack length is obtained considering stable tearing. More details of the analysis and justification of LBB argument as per RCC-MR Appendix A16 are presented in the paper. 相似文献
92.
93.
In order to develop zein fibers with improved physical properties and solvent resistance, formaldehyde was used as a crosslinking reagent before spinning. The crosslinking reaction was carried out in either acetic acid or ethanolic HCl where the amount of crosslinking reagent was between 1 and 6%. Reactions were carried out at various times and temperatures. When carried out in acetic acid, the maximum amount of formaldehyde that could be used was 1.5% as gelation occurred at higher levels. In ethanolic HCl, 6% formaldehyde could be incorporated into zein. All solutions were successfully electrospun, producing predominantly ribbon and round fibers; the morphology was strongly dependent on solvent and spinning solids. The formaldehyde‐crosslinked zein fabrics had double the tensile strength of control fabrics. SDS‐PAGE analysis clearly showed crosslinking had occurred. Electrospun fabrics from all formaldehyde‐treated zein solutions required an additional heating step in order to be resistant to dissolution in acetic acid, a known very good solvent for zein. Copyright © 2011 Society of Chemical Industry 相似文献
94.
95.
Swapnil Y. Dhumal Tyrone L. Daulton Jingkun Jiang Bamin Khomami Pratim Biswas 《Applied catalysis. B, Environmental》2009,86(3-4):145-151
Titanium dioxide is a wide band gap (3.2 eV) semiconductor which is photo-active when irradiated with UV light. For wider scale use of TiO2 as a photocatalyst, its activity needs to be extended to the visible light region (constituting 45% of total incident solar energy). A diffusion flame aerosol reactor (FLAR) with an oxygen lean environment in the particle formation zone has been used to synthesize oxygen deficient titanium suboxide (TiOx with x < 2) nanoparticles. Using a standard-based electron energy loss spectroscopy (EELS) technique, the non-stoichiometry (x in TiOx) in the flame synthesized particles has been quantified with high accuracy (uncertainty less than 3%). Under an oxygen lean environment in the particle formation zone, the non-stoichiometry in the TiOx particles is a function of the flame temperature. The value of x in the flame synthesized TiOx nanoparticles is in the range of 1.88 < x < 1.94. Diffuse reflectance spectra confirmed that the oxygen deficient TiOx particles absorbed visible light. Visible light activity of the TiOx particles is demonstrated by photocatalytic degradation of methyl orange solution under visible light illumination. 相似文献
96.
Asit K. Biswas 《国际水》2013,38(3):489-491
97.
Submerged arc welding is well-known for its very high deposition rate and thus the capability to join very high thickness metal pieces in large structural applications. Fillet joints are mostly used in structural applications which can be extensively seen in shipbuilding, bridge construction, house buildings, automobile or any other large structures. Thermal stresses generates in a fusion welded joint due to high temperature gradient, which is the cause of the residual stresses upon cooling followed by the angular deformation and failure of the welded structure. As an effect of the thermal gradient, the induced longitudinal, transverse residual stress & angular distortion can vary in single sided and double sided submerged arc welded fillet joints, during designing & manufacturing welded structures which should be taken into account. The main objective of this paper is to quantify the amount of residual stresses and angular deformation in a fillet welding joint. An elasto-plastic thermomechanical model has been developed for predicting residual stresses. A comparison of the residual stress and angular deformation between single and double sided fillet weld joint has been made. The simulation results reveal that the amount of residual stress present in the single sided fillet weld is more and unbalanced in both side of the center of weld line compared to the double sided fillet weld and the predicted results have been matched with the experiments as well as published literatures. 相似文献
98.
99.
100.
A. Biswas S. K. Roy J. B. Singh K. Madangopal N. Prabhu 《Journal of Materials Science》2002,37(6):1189-1195
The technique of Self-propagating High-temperature Synthesis (SHS) was used to prepare NiAl from compacts using elemental powder mixtures in stoichiometric amounts under vacuum and argon atmosphere. Considerable changes in the oxygen contents of the specimen before and after the SH-synthesis were not observed. But, unusual occurrence of an impurity phase was noticed in the product as second phase precipitate. The sparsely distributed precipitates could be detected only in the Transmission Electron Microscope and was characterized to be an oxide of aluminium (-Al2O3) containing nickel oxide (NiO), whose solubility in -Al2O3 at room temperature has not been reported earlier. The occurrence of this phase could be traced to the oxygen on the surface of the reactant particles. 相似文献