Large deflection analysis of clamped skew sandwich plates by parametric differentiation

The differential equations governing the large deflection behavior of skew sandwich plates are highly complex in nature and do not lend themselves for easy solution. In the study reported herein, this problem is solved by a numerical technique known as “parametric differentiation”. The non-linear differential equations in terms of displacements are transformed into a set of linear differential equations with variable coefficients. These are solved to give the gradients of the displacements in the load direction. The subsequent solution of a set of initial value problems yield the displacements proper. The results obtained by this method are compared with available results of other investigators and the agreement is found to be good. Load deflection characteristics have been presented for clamped skew sandwich plates.     

Equilibrium constants and thermodynamics of ionization of aqueous hydrogen sulfide

First (K₁) and second (₂) ionization constants for aqueous hydrogen sulfide reported by various investigators have been reviewed, along with results of related calorimetric measurements leading to corresponding enthalpies of ionization. Following critical analysis of the published results, we have selected what we regard as “best” values for the ionization constants and related thermodynamic quantities. We call particular attention to significant uncertainties in these quantities for the higher (above 25°C) temperatures that are generally most important in hydrometallurgy.     

In-vitro enzymic hydrolysis of the storage proteins of japanese barnyard millet (Echinochloa frumentacea)

To assess the nutritional quality of Japanese barnyard millet ( JBN , Echinochloa frumentacea Link), its protein content, quality and digestibility were studied. The proximate composition of the millet resembles that of other millets/cereals. The protein content had a mean value of 36.7 g kg^?1. Solubility fractionation showed glutelins to be the major storage protein (60.8%). Contents of phenolics and tannins were estimated and found to be low. The protein digestibility of JBN flours was high (84%). The digestibilities of the different protein fractions varied from 50.9% to 68.4% with pepsin and from 26.6 mg g^?1 to 55.8 mg g^?1 (α-amino N liberated) with trypsin. These differences have been discussed relative to differences in amino acid composition of the protein fractions as well as to the possible presence of antinutritional factors in the fractions.     

Effect of acid treatment on the formation of SiC whiskers from raw rice husks

Raw rice husks have been treated by boiling for 1 h in 5 N hydrochloric acid. The washed and dried acid-treated raw rice husks (TRRH) and untreated raw rice husks (RRH) were directly pyrolysed (without precoking) in argon atmosphere at different temperatures between 1050 and 1600 °C. Silica obtained from TRRH has a lower level of impurities than that obtained from RRH. Acid treatment has been found to decrease the degree of crystallization of silica and carbon in rice husks. The whisker formation has been decreased in TRRH. As the carbon loss due to the formation of CO was high, the SiC content in the pyrolysed TRRH was higher than that in pyrolysed RRH.     

Hydromagnetic convection flow through a porous medium in axially varying pipe

The hydromagnetic mixed convection flow through a porous medium in a pipe of varying radius in a uniform axial magnetic field is analyzed. The pipe wall is maintained at a prescribed nonuniform temperature. The governing equations are solved analytically to obtain the velocity, temperature, and induced magnetic field. Their behaviors are evaluated for different variations in the governing parameters. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 4, pp. 96–104, July–August, 2006.     

Color tuning of Y3Al5O12:Ce phosphor and their blend for white LEDs

Gadolinium or lanthanum co-doped (0.5 mole) yttrium aluminum garnet doped with cerium phosphors were synthesized by a citric acid gel method and the effect of co-dopants on the structural and luminescent properties were studied. A significant peak shift in the photoluminescence spectra of yttrium aluminum garnet doped cerium was observed from 535 to 556 and 576 nm for gadolinium or lanthanum co-doped phosphors, respectively. The color tuned phosphor were blended with yttrium aluminum garnet doped cerium which showed a considerable improvement in the Commission International De Eclairage chromaticity co-ordinate values of gallium nitride based blue light emitting diode pumped white light. White light emitted from yttrium aluminum garnet doped cerium shows a Commission International De Eclairage value of (0.229, 0.182) whereas the yttrium aluminum garnet doped cerium phosphor blended with gadolinium or lanthanum co-doped phosphor shows (0.262, 0.243) and (0.295, 0.282), respectively. These results demonstrate the possibility to use these phosphor blends to enhance the white light generation in the field of white-light emitting diode solid-state lighting.     

A model of secondary electron imaging in the helium ion scanning microscope

A combination of the ‘semi-empirical’ model for secondary electron production and the TRIM routines which describe ion stopping power, scattering, and transport, has been used to construct a Monte Carlo simulation (IONiSE) that can quantitatively interpret the generation of secondary electrons (SE) from materials by fast helium ions. This approach requires that the parameters of the semi-empirical model be determined by fitting to experimental yield data but has the merit that, unlike more fundamental models, it can be applied with equal ease to both pure elements and complex compounds. The application of the model to predict the topographic yield variation of helium generated SE as a function of energy and material, and to investigate the ratio between SE generated by incident and backscattered ions, is demonstrated.     

Numerical modelling of light gauge cold-formed steel compression members subjected to distortional buckling at elevated temperatures

Fire safety design of building structures has received greater attention in recent times due to continuing loss of properties and lives during fires. However, fire performance of light gauge cold-formed steel structures is not well understood despite its increased usage in buildings. Cold-formed steel compression members are susceptible to various buckling modes such as local and distortional buckling and their ultimate strength behaviour is governed by these buckling modes. Therefore a research project based on experimental and numerical studies was undertaken to investigate the distortional buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. Lipped channel sections with and without additional lips were selected with three thicknesses of 0.6, 0.8, and 0.95 mm and both low and high strength steels (G250 and G550 steels). More than 150 compression tests were undertaken first at ambient and elevated temperatures. Finite element models of the tested compression members were then developed by including the degradation of mechanical properties with increasing temperatures. Comparison of finite element analysis and experimental results showed that the developed finite element models were capable of simulating the distortional buckling and strength behaviour at ambient and elevated temperatures up to 800 °C. The validated model was used to determine the effects of mechanical properties, geometric imperfections and residual stresses on the distortional buckling behaviour and strength of cold-formed steel columns. This paper presents the details of the numerical study and the results. It demonstrated the importance of using accurate mechanical properties at elevated temperatures in order to obtain reliable strength characteristics of cold-formed steel columns under fire conditions.     

Postbuckling analysis of cross-ply laminated cylindrical shell panels under parabolic mechanical edge loading

Postbuckling equilibrium paths of simply supported cross-ply laminated cylindrical shell panels subjected to non-uniform (parabolic) inplane loads are traced in this paper. Love's shell theory with higher order shear deformation theory and von Kármán nonlinear strain–displacement relations are used in the mathematical formulation of the problem. In the first step, the plate membrane problem is solved to evaluate the stress distribution within the prebuckling range as the applied inplane edge load is non-uniform. The governing shell panel postbuckling equations are derived from the principle of minimum total potential energy using the above stress distributions. Adopting multi-term Galerkin's approximation, the governing equations are reduced into a set of non-linear algebraic equations. Newton–Raphson method in conjunction with Riks approach is employed to plot the postbuckling paths through limit points. Numerical results are presented for symmetric (0/90/0) crossply laminated cylindrical shell panels under parabolic inplane load, lateral distributed load and initial imperfections. Limit loads and snap-through behavior of shell panels are studied.     

Cobalt Schiff base complexes: Synthesis characterization and catalytic application in Suzuki–Miyaura reaction

3-Methoxysalicylaldehyde was condensed with the amines 4-aminoacetophenone and 2-amino-5-bromopyridine to obtain Schiff base ligands, 1 and 2, which were coordinated to cobalt salts as complex 1 and complex 2, respectively. The synthesized ligands and complexes were characterized by spectroscopic (FT-IR, UV-Vis, ¹H-NMR and mass spectrometry), thermal (TGA) and elemental analysis. The structures of the complexes were verified by evaluating their magnetic susceptibility and spectroscopic evidences. Synthesized complexes were studied for their catalytic activity in the Suzuki-Miyaura cross-coupling of aryl halides with phenylboronic acid. Optimized reaction yields 90% of the cyanobiphenyl for complex 1 and 91% for complex 2 with 0.1 mmol of catalyst loading thereby substantiating the C-C coupling efficiency of the synthesized complexes, 1 and 2.