Design and operation characteristics of a high power transverse flow pulser sustained cw CO2 laser

A transverse flow, transverse discharge cw CO₂ laser in which de discharge is sustained by employing high repetition rate high voltage pulses has been developed. Pulser sustained discharge through electrodes of innovative design provided uniform excitation at electrical input power densities more than 10 W/cc. Laser output power more than 2.5 kW was obtained in a laser gas mixture consisting of 0.5 mbar of CO₂, 16 mbar of N₂ and 38.5 mbar of He. Design details and operational characteristics of this laser are presented.     

Conductivity and dielectric properties of sol–gel derived porous zirconia

The 8-mol percentage Y₂O₃-stabilized Porous Zirconia was prepared using sol–gel method. Zirconium oxalate gel was prepared by the addition of appropriate amount of oxalic acid solution into the 1 M aqueous solution of zirconium-oxy chloride. A cubic phase zirconia powder was obtained by calcination and milling of the zirconium oxalate gel. Crystallization temperature was found about 450 °C from the Differential thermal analysis. The phase analysis by X-ray diffraction shows the presence of cubic phase. Pellets sintered at 1,350 °C were highly porous, and the electrical conductivity was found with lower value due to the porosity, and the hardness was about 8.0 GPa. Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006.     

Simultaneous approximation for the Bézier variant of Baskakov-Beta operators

In the present paper, we study the rate of convergence in simultaneous approximation for the Bézier variant of the Baskakov-Beta operators by using the decomposition technique of functions of bounded variation.     

HPTLC Determination of Swertiamarin and Amarogentin in Swertia Species from the Western Himalayas

JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatographic (HPTLC) method has been established for simple and rapid quantification of two...     

Construction of spiro[5.5]undecanes containing a quaternary carbon atom adjacent to a spirocentre via an Ireland ester Claisen rearrangement and RCM reaction sequence. Total syntheses of (±)-α-chamigrene, (±)-β-chamigrene and (±)-laurencenone C

Starting from cyclohexanecarboxylic acid, a combination of an Ireland ester Claisen rearrangement and RCM reactions was exploited for an efficient construction of spiro[5.5]undecanes containing a quaternary carbon atom adjacent to the spirocentre and the methodology was extended to complete total syntheses of three chamigrenes.     

“Optimization of aircraft maintenance/support infrastructure using genetic algorithms—level of repair analysis”

Level of repair analysis (LORA) is an approach used during the design stage of complex equipment for analysis of the cost effectiveness of competing maintenance strategies. LORA is carried as a part of the life cycle cost and cost of ownership analysis and plays a significant role in minimizing the life cycle cost and cost of ownership of the capital equipment. Since many purchasing decisions of complex equipment are based on cost of ownership, it has become essential to carry out LORA to compete in the market. In this paper, we develop a mathematical model for LORA and propose a solution methodology based on genetic algorithms. The concept is illustrated using a hypothetical aircraft engine.     

Buckling of laminated plates - A simple finite element based on higher-order theory

A four-noded rectangular element with seven degrees of freedom at each node is developed for buckling analysis of laminated plate structures having any number of layers with a constant thickness of individual layers. The displacement model is so chosen that it can explain adequately the parabolic distribution of transverse shear stresses and the non-linearity of in-plane displacements across the thickness. A geometrical stiffness matrix is developed using in-plane stresses. A wide range of plates from thick to thin are examined under uniaxial loading conditions. The results are compared with the existing analytical and numerical solutions. The present formulations confirm its applicability for buckling analysis of a wide range of plates.     

Effects of saturation on optical bistability with coupled surface plasmons

We present exact numerical results for a symmetric layered medium (prism/Ag film/nonlinear dielectric/Ag film/prism) where the middle dielectric slab is assumed to have a saturation-type nonlinearity. We show bistable behaviour in the power dependence of the reflectivity ofp-polarized light under the condition when coupled surface modes are excited in the structure. Moreover, we study the effect of saturation on the bistable behaviour to show that multivalued character is inhibited by saturation effects. The field distributions corresponding to the minimum reflectivity states of the nonlinear structure are also presented.     

Effect of the three-body force on triton asymptotic normalization constants by the hyperspherical harmonics expansion method

We investigate the change in the calculated value of asymptotic normalization constant (ANC) by the hyperspherical harmonics expansion method with the inclusion of three nucleon force (3BF) in addition to two nucleon force. We see that ANC does not change very much with the inclusion of 3BF indicating that the 3BF does not alter the asymptotic behaviours of HHE wavefunction significantly.     

Laser induced air breakdown using 0.355, 0.532, and 1.06 µm radiation

Studies of breakdown threshold intensity for air at various pressures in the range of 24–760 torr using 0.355, 0.532 and 1.06 μm radiation are reported. We observep ^−0.8 scaling ofI _th at 1.06 μm and a weak scaling ofp ^−0.4 at 0.532 and 0.355 μm radiation. Strong dependence of breakdown spot size on laser power but weak dependence on air pressure is observed.