Structural efficiency studies of corrugated compression panels with curved caps and beaded webs

Curved cross-sectional elements are employed in structural concepts for minimum-mass compression panels. Corrugated panel concepts with curved caps and beaded webs are optimized by using a nonlinear mathematical programming procedure and a rigorous buckling analysis. These panel geometries are shown to have superior structural efficiencies compared with known concepts published in the literature. Fabrication of these efficient corrugation concepts became possible by advances made in the art of superplastically forming of metals. Results of the mass optimization studies of the concepts are presented as structural efficiency charts for axial compression

Analysis Of Mechanical Properties And Free Vibration Response Of Composite Laminates

The Word composite consisting of two or more distinct materials, having two or more distinct phases with different physical properties are noticeable different from the constituent properties. Of all composite materials the fabric type has evoked the most interest among embedded in matrix materials to form laminated composites. These have been used for centuries and today industrial innovation improved energy planning. Uncertain availability and ever increasing cost have created a greater interest in composites. The engineering importance of a composite material is that two or more distinctly different materials with dissimilar characteristics combine together to form a composite that is either superior or important in some other manner to the properties of the individual materials. Most of the composites have been created to improve combinational of mechanical characteristics such stiffness, wear resistance and mechanical properties

Sensitizing Efficiency of Some Added Metal Salts on the Thermal and Explosive Characteristics of Hydrazenium Monoperchlorate and Hydrazenium Diperchlorate

Sensitivity to heat, impact and friction of hydrazenium-monoperchlorate and hydrazenium-diperchlorate have been investigated and the sensitizing efficiency of some added metal salts evaluated. The thermal sensitizing efficiency of the additives follow the order CuCrO/sub 4/ > CuCl/sub 2/ >NiO > Fe/sub 2/O/sub 3/ > MgO. The activation energy values obtained from explosion delay time are comparable with the values reported for thermal decomposition studies and are close to the activation energy value for thermal decomposition studies and are close to the activation energy value for thermal decomposition of anhydrous perchloric acid. The F of I values for these compounds are in the range reported for common initiatory explosives and are of the same order as that for mercury fulminate

Magnetic spectrum of the two-dimensional antiferromagnet La2CoO4 studied by inelastic neutron scattering

We report measurements of the magnetic excitation spectrum of the layered antiferromagnet La2CoO4 by time-of-flight neutron inelastic scattering. In the energy range probed in our experiments (0-250 meV) the magnetic spectrum consists of spin-wave modes with strong in-plane dispersion extending up to 60 meV, and a nearly dispersionless peak at 190 meV. The spin-wave modes exhibit a small (~1 meV) dispersion along the magnetic zone boundary. We show that the magnetic spectrum can be described very well by a model of a Heisenberg antiferromagnet that includes the full spin and orbital degrees of freedom of Co2+ in an axially-distorted crystal field. The collective magnetic dynamics are found to be controlled by dominant nearest-neighbour exchange interactions, strong XY-like single-ion anisotropy and a substantial unquenched orbital angular momentum.Comment: 8 pages, 7 figure

High temperature onset of field-induced transitions in the spin-ice compound Dy2Ti2O7

We have studied the field-dependent ac magnetic susceptibility of single crystals of Dy2Ti2O7 spin ice along the [111] direction in the temperature range 1.8 K - 7 K. Our data reflect the onset of local spin ice order in the appearance of different field regimes. In particular, we observe a prominent feature at approximately 1.0 T that is a precursor of the low-temperature metamagnetic transition out of field-induced kagome ice, below which the kinetic constraints imposed by the ice rules manifest themselves in a substantial frequency-dependence of the susceptibility. Despite the relatively high temperatures, our results are consistent with a monopole picture, and they demonstrate that such a picture can give physical insight to the spin ice systems even outside the low-temperature, low-density limit where monopole excitations are well-defined quasiparticles

4-Aminoantipyrine Complexes of Fe(II)

134-13

Magnetic & Spectral Studies on Ni(II) & Cu(II) Complexes of N-(Salicylidene)phenylhydrazine

536-53