Mineralogical changes and geotechnical properties of an expansive soil interacted with caustic solution

The type and amount of clay mineral plays an important role in the behaviour of fine-grained soils. Clay minerals are the primary source and moisture is often the external agent of swelling in soils. Also soils may exhibit increased/reduced swelling due to interaction with chemicals. Alkalis used in industrial operations are one such example. Concentrations of alkali and mineral type are the key factors in such interactions. The present paper reports the changes in the properties of an expansive Black Cotton soil containing a mixed layer mineral, rectorite upon interaction with high concentration caustic solutions. X-ray diffraction studies have shown that the rectorite present in the soil undergoes changes with increase in the concentration of alkali. Saponite gets transformed to nantronite. Small amount of kaolinitic mineral present in the soil also reacts with alkali producing some changes in its mineralogy. Many hydroxides are produced. Differential thermal analysis studies have been supportive of these changes. Consequent of these changes, the soil-specific surface increases, changes its Atterberg limits and free swell volume increases. The results have been supported by the characteristics and behaviour of samples contaminated in the field with alkali from an alumina extraction plant.

Analysis of continuous beams—a three dimensional elasticity solution

A three dimensional elasticity solution for the analysis of beams continuous over an infinite number of equally spaced supports has been given. The beam has been subjected to normal tractions on its two opposite faces and these loads are identical over each span. The other two faces are traction free. Numerical results have been given for different cases when the beam is loaded on its bottom face. The results obtained have been compared with the results of two dimensional elasticity solution.

A general treatment of two dimensional plane flows, for a micropolar fluid

In this paper we have studied the flow of a micropolar fluid, whose constitutive equations were given by Eringen, in two dimensional plane flow. In two notes, we have discussed the validity of the boundary condition v=a ω and its effect on the entire flow field. We have restricted our study to the case when Stokes' approximation is valid, i. e. slow motion for it is difficult to uncouple the equations in the most general case.

A class of one-dimensional steady-state flows in radiation-gas-dynamics

The study of steady-state flows in radiation-gas-dynamics, when radiation pressure is negligible in comparison with gas pressure, can be reduced to the study of a single first-order ordinary differential equation in particle velocity and radiation pressure. The class of steady flows, determined by the fact that the velocities in two uniform states are real, i.e. the Rankine-Hugoniot points are real, has been discussed in detail in a previous paper by one of us, when the Mach number M of the flow in one of the uniform states (at x=+∞) is greater than one and the flow direction is in the negative direction of the x-axis. In this paper we have discussed the case when M is less than or equal to one and the flow direction is still in the negative direction of the x-axis. We have drawn the various phase planes and the integral curves in each phase plane give various steady flows. We have also discussed the appearance of discontinuities in these flows.

A three-dimensional solution for plates and laminates

A general three-dimensional solution is presented for statics and dynamics of plates, homogeneous or laminated, of orthotropic materials. The solution is in series form. Using parts of the general solution a variety of problems, especially of rectangular configurations, can be solved. As Mindlin's approximate analysis for vibration of thick plates is often adequate for specific practical purposes, a general solution for Mindlin's analysis is also given.

Oligarchs, political regime changes, and firm valuation

This paper examines the impact of a regime shift on the valuation of politically powerful oligarch firms. Focusing on the Yeltsin-Putin regime shift in Russia, we find that the valuations of outside shareholders claims are significantly higher under the Putin regime than under the Yeltsin regime after controlling for industry and time effects. The findings suggest that the increasing cost of extracting private benefits outweigh the reduction in the value of political connections following the political regime change. The results are also consistent with changes in the risk of state expropriation. Our results show that effects driven by the political regime change complement the traditional view stating that increased ownership concentration improved the performance of Russian oligarch firms.

Three-Dimensional simulation of deformation fields underneath vickers indenter:Effects of power-law Plasticity

The effects of power-law plasticity (yield strength and strain hardening exponent) on the plastic strain distribution underneath a Vickers indenter was systematically investigated by recourse to three-dimensional finite element analysis, motivated by the experimental macro-and micro-indentation on heat-treated Al-Zn-Mg alloy. For meaningful comparison between simulated and experimental results, the experimental heat treatment was carefully designed such that Al alloy achieve similar yield strength with different strain hardening exponent, and vice versa. On the other hand, full 3D simulation of Vickers indentation was conducted to capture subsurface strain distribution. Subtle differences and similarities were discussed based on the strain field shape, size and magnitude for the isolated effect of yield strength and strain hardening exponent.

Anomalous behavior of hydrodynamic modes in the two dimensional shear flow of a granular material

The growth rates of the hydrodynamic modes in the homogeneous sheared state of a granular material are determined by solving the Boltzmann equation. The steady velocity distribution is considered to be the product of the Maxwell Boltzmann distribution and a Hermite polynomial expansion in the velocity components; this form is inserted into them Boltzmann equation and solved to obtain the coeificients of the terms in the expansion. The solution is obtained using an expansion in the parameter epsilon =(1 - e)(1/2), and terms correct to epsilon(4) are retained to obtain an approximate solution; the error due to the neglect of higher terms is estimated at about 5% for e = 0.7. A small perturbation is placed on the distribution function in the form of a Hermite polynomial expansion for the velocity variations and a Fourier expansion in the spatial coordinates: this is inserted into the Boltzmann equation and the growth rate of the Fourier modes is determined. It is found that in the hydrodynamic limit, the growth rates of the hydrodynamic modes in the flow direction have unusual characteristics. The growth rate of the momentum diffusion mode is positive, indicating that density variations are unstable in the limit k--> 0, and the growth rate increases proportional to kslash} k kslash}(2/3) in the limit k --> 0 (in contrast to the k(2) increase in elastic systems), where k is the wave vector in the flow direction. The real and imaginary parts of the growth rate corresponding to the propagating also increase proportional to kslash k kslash(2/3) (in contrast to the k(2) and k increase in elastic systems). The energy mode is damped due to inelastic collisions between particles. The scaling of the growth rates of the hydrodynamic modes with the wave vector I in the gradient direction is similar to that in elastic systems. (C) 2000 Elsevier Science B.V. All rights reserved.