Quantification of microcrack anisotropy in quartzite — a comparison between experimentally undeformed and deformed samples

In this paper, microcrack patterns in a quartzite are quantified using fractal geometry based methods. Since the quartzite does not show a mesoscopic foliation, the fabric was recognized using anisotropy of magnetic susceptibility (AMS) analysis. Microcracks were investigated in thin sections prepared along the three principal planes of the AMS ellipsoid. Point load tests were performed on cores drilled parallel as well as perpendicular to the magnetic foliation. After experimental deformation, thin sections were prepared in two orientations — (a) parallel to the plane of failure (i.e., parallel to the direction of loading), (b) perpendicular to the plane of failure (i.e., perpendicular to the direction of loading), and microcrack patterns in these sections were investigated. The box-counting method of fractal analysis was first applied to microcracks traced from SEM images from each thin section of the experimentally undeformed as well as deformed samples to establish the fractal nature of the microcrack pattern. It was found that in thin sections perpendicular to the direction of loading, the box (fractal) dimension tends to marginally increase. This is inferred as a manifestation of the increase in complexity of the pattern. The software AMOCADO, which is based on the modified Cantor Dust method of fractal analysis, was applied to microcrack pattern from each thin section in order to quantify the pattern anisotropy. It is noted that the anisotropy significantly reduces in sections perpendicular to the loading direction. SEM data are presented to demonstrate that this reduction in anisotropy is on account of generation and/or growth of new cracks in random orientations. It is envisaged that the approach adopted in this investigation maybe useful in rock mechanics and mineral-resource applications in future.     

Analytical solutions for Euler–Bernoulli beam on visco‐elastic foundation subjected to moving load

Analytical solutions for the steady‐state response of an infinite beam resting on a visco‐elastic foundation and subjected to a concentrated load moving with a constant velocity are developed in this paper. The beam responses investigated are deflection, bending moment, shear force and contact pressure. The mechanical resistance of the foundation is modeled using two parameters k_s and t_s — k_s accounts for soil resistance due to compressive strains in the soil and t_s accounts for the resistance due to shear strains. Since this model represents the ground behavior more accurately than the Winkler spring model, the developed solutions produce beam responses that are closer to reality than those obtained using the existing solutions for Winkler model. The dynamic beam responses depend on the damping present in the system and on the velocity of the moving load. Based on the study, dynamic amplification curves are developed for beam deflection. Such amplification curves for deflection, bending moment, shear force and contact pressure can be developed for any beam‐foundation system and can be used in design. Copyright © 2012 John Wiley & Sons, Ltd.     

Absorption features of QSOs

Absorption features shown by QSOs may be identified and measured as reported absorption redshift systems, or may remain unidentified and not measured. The features are believed to be observed in objects with high emission redshifts (z _em), although no quantitative analysis exists to examine any such preferential trend, except that by Basu (1982). However, redshift data have since increased enormously both in range of the redshift spectrum and in number. Furthermore, the earlier analysis was based on only the reported absorption redshifts while unidentified absorption features were not dealt with. The present paper analyses the updated data, both identified and unidentified features. It is found that absorption features may be expressed as exponential function ofz _em, and upper limits are set for the percentage of QSOs showing absorption features. Finally, an entirely new method of analysis confirms the earlier conclusion of Basu (1982) that the appearance of absorbing clouds is closely associated with the creation of the QSOs, the two may be having a common cause. It is suggested that absorption QSOs may be a separate class of QSOs whose birth is accompanied with creation of absorbing clouds.     

New technologies, old divides: linking internet access to social and locational characteristics of US farms

Access to new information and communication technologies is widely viewed as a prerequisite for participation in the global economy, so that inequalities in such access have become a significant policy concern. Rural areas are especially underserved in terms of internet providers, and this is true in both developed and less developed economies. This article focuses on access to the internet within farming operations in the US as an important aspect of understanding the digital divide within rural areas. Using county level data from the 2007 US Census of Agriculture and multivariate regression analysis, our study examines the statistical relationship between farm internet access and a set of explanatory factors which include demographic characteristics of operators, economic characteristics of farms, and geographic location (region and metropolitan status) of the farm. Further, it seeks to understand whether access to the internet can be socially and locationally differentiated from access to high speed internet. Our findings indicate that existing social divides are replicated in terms of the digital divide, so that social inequalities are potentially a more pressing problem than infrastructural gaps in terms of rural access to the internet in the US.     

Possible solar cycle variations in the convection zone

Using data from the Global Oscillations Network Group (GONG) that covers the period from 1995 to 1998 we study the change in frequencies of solar oscillations with solar activity. From these frequencies we attempt to determine any possible variation in solar structure with solar activity. We do not find any evidence of a change in the convection zone depth or extent of overshoot below the convection zone during the solar cycle.     

Temporal variation of large scale flows in the solar interior

We attempt to detect short-term temporal variations in the rotation rate and other large scale velocity fields in the outer part of the solar convection zone using the ring diagram technique applied to Michelson Doppler Imager (MDI) data. The measured velocity field shows variations by about 10 m/s on the scale of few days.     

Eddy Detection Over Southern Indian Ocean Using TOPEX/POSEIDON Altimeter Data

Field biological and geomorphological observations in certain East Asia coasts permit definition of Mean Sea Level (MSL) with an accuracy of ～10 cm, that is, a vertical geodetic datum, as well as recognition of the MSL of fossil shorelines, up to a few thousand years old, mainly associated with tectonic/seismic effects. Subsidence produced by compaction of nearly-surficial strata seems also to be a usual effect. These data indicate that datum variability is a widespread effect in East Asia, time-dependent even at time scales affecting engineering works, but only in a few cases fully predictable.     

Numerical simulation of the marine boundary layer characteristics over the Bay of Bengal as revealed by BOBMEX-98 Pilot experiment

An attempt has been made to study the marine boundary layer characteristics over Bay of Bengal using BOBMEX (Bay of Bengal and Monsoon Experiment) pilot experiment data sets, which was conducted between 23rd October and 12th November 1998 on board ORV Sagar Kanya. A one-dimensional multilevel atmospheric boundary layer with TKE-ε closure scheme is employed to study the marine boundary layer characteristics. In this study two synoptic situations are chosen: one represents an active convection case and the other a suppressed convection. In the present article the marine boundary layer characteristics such as temporal evolution of turbulent kinetic energy, height of the boundary layer and the airsea exchange processes such as sensible and latent heat fluxes, drag coefficient for momentum are simulated during both active and suppressed convection. Marine boundary layer height is estimated from the vertical profiles of potential temperature using the stability criterion. The model simulations are compared with the available observations.     

Effect of soil interaction on the performance of liquid column dampers for seismic applications

The effects of soil–structure interaction (SSI) while designing the liquid column damper (LCD) for seismic vibration control of structures have been presented in this study. The formulation for the input–output relation of a flexible‐base structure with attached LCD has been presented. The superstructure has been modelled by a single‐degree‐of‐freedom (SDOF) system. The non‐linearity in the orifice damping of the LCD has been replaced by equivalent linear viscous damping by using equivalent linearization technique. The force–deformation relationships and damping characteristics of the foundation have been described by complex valued impedance functions. Through a numerical stochastic study in the frequency domain, the various aspects of SSI on the functioning of the LCD have been illustrated. A simpler approach for studying the LCD performance considering SSI, using an equivalent SDOF model for the soil–structure system available in literature by Wolf (Dynamic Soil–Structure Interaction. International Series in Civil Engineering and Engineering Mechanics. Prentice‐Hall: Englewood Cliffs, NJ, 1985) has also been presented. Copyright © 2005 John Wiley & Sons, Ltd.