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The author has studied several failures in the field of bent and branched copper-nickel pipelines exposed to marine environments contaminated by ammoniacal byproducts. The cause of the failures was investigated by laboratory tests on the Cu-5.37 wt-%Ni alloy used for the failed pipes. The tests were conducted under slow strain rate testing (SSRT) conditions, in aqueous ammonia and ammoniacal sea water environments. These studies revealed that the presence of ammonia in sea water impairs the load bearing capacity of the alloy, and the aqueous ammonia environments tend to cause brittle stress corrosion cracking failures, which are often premature and/or catastrophic. However, in addition to induced residual stresses from manufacturing/processing, the operating conditions in marine environments subject these pipes to external forces and widely varying pressures and fluid flow rates, which can cause both static and cyclic stresses. Experiments conducted under SSRT conditions, however, could not predic...

The test results from an earlier investigation by the author on the mechanical behaviour of a low nickel nickel-copper alloy exposed to a solution of 3·5%NaCl + 10%MgCl2 with and without ammonia indicated that the presence of 1% ammonia alters the failure mode and affects the load bearing capacity of the material. In the present investigation, further tests have been conducted on the same alloy to study its mechanical/corrosion behaviour on exposure to an aqueous solution of ammonia in comparison with exposure to a similar solution of ammonia containing 3·5%NaCl + 10%MgCl2. A constant displacement rate of 9·6 × 10-3 μ m s-1 was used and the concentration of ammonia was maintained at 5%. On exposure to the 5% aqueous ammonia solution, the mechanical properties of the alloy were degraded significantly and the material exhibited a brittle stress corrosion type of failure. However, on exposure to 5% ammonia in the presence of 3·5%NaCl + 10%MgCl2, there was less change in failure mode relative to that ...

A low nickel copper alloy commonly used in the plumbing/drainage pipelines on ships was investigated under slow strain rate conditions in air, and in solution containing 3·5%NaCl + 10%MgCl2, with and without 1% ammonia. The tests were conducted at ambient temperature (28 ± 1°C) at strain rates corresponding to a crosshead speed of 5·76 × 10-5cm min-1, without a passivation current. The results obtained did not show any significant deterioration in the mechanical properties of the alloy in the tests conducted in air or in solution without ammonia. However, with the introduction of 1% ammonia, a reduction in the material strength and a change in the mode of failure were observed. This paper discusses the results obtained in the present investigation and in particular the load bearing capacity of the material and the modes of failure in Cu–Ni alloys exposed to sea water.

The paper deals with the theory of Whistler propagation in a weakly drifting magnetoplasma. The equation for the refractive index (n) for this type of propagation has been derived. It is found that the complex value of the refractive index (n) for this type of propagation is independent of the drift velocity.

The paper deals with oblique wave propagation in inhomogeneous compressible electron plasmas. The refractive index equation has been derived for arbitrarily directed oblique waves in inhomogeneous compressible plasma. The q factor obtained in the present investigation obeys a general third order algebraic equation.

This paper deals with the studies of the mode conversion problems involved in the H-plane semicircular waveguide bent. Expressions for the conversion coefficient for different modes have been derived and calculated as a function of bent angle and the radius of the waveguide.

The paper deals with some aspects of electromagnetic wave propagation in the Martian ionosphere. Using recent data, the effective collision frequency and high frequency conductivity have been calculated for all the three models, namely F2, F1 and E. The real part of the complex refractive index is then calculated for νeff = 0 and νeff ≠ 0. The results are then discussed in some detail and it is concluded that propagation of electromagnetic waves below 100 kHz range is not possible through the Martian ionosphere.

The paper deals with the lateral deviation of radio waves reflected from ionosphere and specifically the effect of collisions on it has been studied for frequency range 1–9 kc/s. It is shown that collisions have negligible effect on the lateral deviation of magnetoionic components.

The paper deals with the propagation of elf and vlf waves in abnormally ionized lower atmosphere. The absorption of these waves in whistler mode propagation has been calculated for three disturbed conditions (PCA event, solar flares and nuclear explosion) and ambient condition of the lower ionosphere. It is found that due to enhanced ion density, elf waves suffer more absorption than that suffered by vlf waves.

This paper deals with the study of light transmission through multi-layered dielectric slab. It is Seen that W type structure is quite suitable. Some important computations for such a structure are presented.

The equation of refractive index for whistler mode propagation in drifting magnetoplasma derived by Agarwal1 is considered for large values of Z, an expression for the complex refractive index being derived. To a first approximation, it is found that the imaginary part of the refractive index is unaffected by the imposed magnetic field, while the real part depends on the longitudinal component of the field.

The effect of large values of Zi = νi/ω and Ze = νe/ω (where νi and νe are the frequency of collisions of ions and electrons respectively and ω is the angular frequency of the propagating wave) on the general refractive index (n = μ—iχ) of the ionosphere has been studied. The complex value of n has been evaluated taking into account the effects of magnetic field, ion and temperature using McLaurin's expansion. For the particular case of no magnetic field, the imaginary component of n is found to be independent of temperature effects.