Stresses and displacements in an elastic mass due to distributed loading by discretization technique

Numerical solutions have been obtained for stresses and displacements in a linear elastic half space due to distributed loads of circular, rectangular and elliptical shapes. The technique primarily involves use of a multi-dimensional numerical integration technique to integrate point load solutions over the distributed loading after discretizing the area into a finite number of elements. Both uniform vertical and shear loads have been considered as well as vertical conical loads and inward shear loads. The technique evolved facilitates the determination of stresses and displacements by the use of mini-computers and is neither as tedious and cumbersome as the use of tables and charts nor as costly as FEM solutions. A detailed comparison has been presented between the results obtained by the numerical solutions and those of the existing analytical solutions wherever they are available. It is found that the agreement between the two is within one per cent for displacements at all depths for the different cases studied. The matching is also good in the case of stresses, except at shallow depths.     

Thermal plasma enhancements in the topside ionosphere and their relationship to the auroral electrojets

Data from the Topside sounder aboard ISIS II are used to calculate the latitudinal distribution of thermal plasma at 1400 km when the satellite moves along a line of constant geographic longitude. The distribution of thermal plasma is related to the latitudinal regime of the auroral electrojets as inferred from data from a meridian line of magnetometers. It is found that thermal plasma at high altitude tends to be found above the poleward portion of the auroral electrojet. This finding is explained in terms of the spectrum of precipitating electrons across the auroral oval. It is found that the thermal plasma distribution in the post-noon sector is distinctly different from that in the premidnight sector despite the fact that both quadrants feature clear latitudinally confined eastward current flow. This difference can be used to define whether or not the polar cleft penetrates into the local time sector traversed by the satellite. On the nightside, the peak in thermal plasma poleward of the ionospheric trough can be used to identify the magnetic field lines which map to the boundary between the tail lobe and the plasma sheet.     

Correlation of studies of surface-level carbon monoxide concentrations and sodar-observed thermal structures

Measured concentration levels of carbon monoxide present in the atmosphere near the ground surface have been studied in relation to atmospheric stability inferred from acoustic sounder vis-à-vis the density of motor-vehicular traffic responsible for the emission of carbon monoxide gas. It has been seen that concentration levels of carbon monoxide during peak traffic hours depend on the prevailing stability of the atmosphere. The need for continuous monitoring of atmospheric stability at a place using acoustic sounder to assess air quality has been emphasized.     

Temperature dependence of CO2 solubility in high pressure quenched glasses of diopside composition

The temperature dependence of carbon dioxide solubility in glasses of diopside composition, quenched from 20 kbar, has been investigated using a combination of high-temperature mass spectrometry and Raman spectroscopy.CO₂-charged diopside glasses were synthesized in a piston-cylinder apparatus. Because of diffusion of hydrogen through the platinum capsules, significant amounts of H₂O, CH₄ and CO were detected along with CO: in the diopside glasses. All three carbon species show a bimodal release pattern in the mass pyrograms. The CO₂ solubility shows a linear and negative temperature dependence. We do not observe any maxima in the solubility curve as was reported previously (Mysen and virgo, 1980a).None of the additional bands observed in Raman spectra of CO₂-charged diopside glasses compared to those in the spectrum of diopside glass can be assigned to molecular CO₂. These bands are caused by CO^?2₃ ions and indicate that the physical solubility of molecular carbon dioxide is negligible. The bimodal release pattern observed for CO₂ in the mass pyrograms, is consistent with the Raman data which strongly suggests that CO^?2₃ ions are present in at least two distinct sites in the glass.     

Streamflow forecasting in remote areas

Forecasts of runoff volumes are required in order to maximize the utility of water-supply sources. In remote areas where hydrologic and land-use data are sparse, forecast models are needed; such models should be conceptually rational so they can be transferred to remote watersheds where data are sparse. A series of models were calibrated for a large watershed in India. A spatially-distributed seasonally-varying model having a structure similar to the rational method was found to provide precise, unbiased estimates of 10-day streamflow volumes. The model was tested on a watershed that was not used for calibration, with the results indicating a high correlation between the observed and measured streamflow. Thus, the model should provide good estimates of streamflow volumes on other ungaged watersheds.     

Analyses and settlement study of a group of two,three and four partially stiffened floating granular piles

ABSTRACT

Use of granular pile as a ground improvement technique in case of soft soils is one of the reliable and economic options. Analysis of a partially stiffened group of granular floating piles has been numerically assessed and presented here. Partial stiffening simply means that instead of using conventional material for making the granular pile (GP) in its full length, top region is replaced partially by some suitable material, having better mechanical properties, i.e. higher deformation modulus. Various normalised parameters like settlement influence factor for top of GP, settlement interaction factor, settlement reduction factor, percentage load shared by the base and shear stress distribution along the length of the granular pile are evaluated. The settlement influence factor for top of GP is found to decrease with the increase in the values of the stiffening parameters. The interfacial shear stresses get redistributed along the length of the granular pile.     

Computation of regional gravity anomaly — A novel approach

A new scheme is put forward based on the shape function concept of finite element approximation to compute regional gravity anomaly. The uniqueness of this approach is that excepting eight (or twelve) discrete gravity measurements coinciding with the eight (or twelve) nodes of a quadratic (or cubic) isoparametric element superimposing the map space, often very large, no other observed gravity data are invoked to compute the regional. Tests on two Bouguer gravity fields, an oil prospect and a rift valley confirmed better resolution by this approach. This technique is straight forward, uses simple mathematics to be easily automated and yields repeatable results.     

Selection of a kernel bandwidth for measuring dependence in hydrologic time series using the mutual information criterion

  Mutual information is a generalised measure of dependence between any two variables. It can be used to quantify non-linear as well as linear dependence between any two variables. This makes mutual information an attractive alternative to the use of the correlation coefficient, which can only quantify the linear dependence pattern. Mutual information is especially suited for application to hydrological problems, because the dependence between any two hydrologic variables is seldom linear in nature. Calculation of the mutual information score involves estimation of the marginal and joint probability density functions of the two variables. This paper uses nonparametric kernel density estimation methods to estimate the probability density functions. Accurate estimation of the mutual information score using kernel methods requires selection of appropriate smoothing parameters (bandwidths) for use with the kernels. The aim of this paper is to obtain a practical method for bandwidth selection for calculation of the mutual information score. In this paper, the lag-one dependence structures of several autocorrelated time series are analysed using mutual information (note that this produces the lag-one auto-MI score, the analog of the lag-one autocorrelation). Empirical trials are used to select appropriate bandwidths for a range of underlying autoregressive and autoregressive-moving average models with normal or near-normal parent distributions. Expressions for reasonable bandwidth choices under these conditions are proposed.