Pre-processing of TerraSAR-X Data for Speckle Removal: An Approach for Performance Evaluation

Measures to select despeckling filter to remove speckles from TerraSAR-X image have been evaluated for an area having varied land cover classes. Gamma, Lee, Sigma, Mean, Median and Frost filters were applied in different window sizes. These images are visually compared and four parameters viz. Noise Mean Value (NMV), Noise Variance (NV), Mean Square Difference (MSD) and Equivalent Numbers of Looks (ENL) are calculated. These parameters were well implemented to compare results of various despeckling filters on TerraSAR-X image recorded in high resolution spot mode and checked for the constraints. Median 7x7 filter was found most suitable among other filters to despeckle the images.     

MODFLOW based groundwater resource evaluation and prediction in Mendha sub-basin,NE Rajasthan

A direct approach to designing MODFLOW finite difference model is tedious and less intuitive, specifically for complex boundary and initial conditions. Therefore, a MODFLOW model can be developed either using a grid or conceptual model approach. The conceptual model is created using Geographic Information System (GIS) objects including points, arcs and polygons so that it can more accurately represent real world condition. It is a simplified representation of the site to be modelled including the model domain, boundary conditions, sources, sinks and material zones. Advantage of conceptual model is that most of the input can be in terms of physical objects, such as wells, lakes, recharge zones etc which can then be converted to a grid based mathematical model with the help of preprocessor software. This paper presents the results of a mathematical groundwater model developed for the northern part of Mendha sub-basin in the semi arid region of northeastern Rajasthan, employing conceptual groundwater modelling approach. For this purpose, Groundwater Modelling Software (GMS) was used which supports the MODFLOW-2000 code. For the purpose of modelling the Source/ Sink Coverage, Recharge Coverage, Extraction Coverage, Return Flow Coverage and Soil Coverage were considered. The model was calibrated against the historical and observed water level data for periods 1998 to 2003 and 2003 to 2005 respectively.     

Effect of non-aqueous drilling fluid and its synthetic base oil on soil health as indicated by its dehydrogenase activity

Drilling fluids are used for drilling natural gas, oil and water wells. These spill over into the surrounding soil at the point of drilling, which may impair soil health. A laboratory investigation was carried out to determine the effect of non aqueous drilling fluid (NADF) and synthetic base oil used with it on soil health as indicated by the dehydrogenase activity. A non-sterile sandy loam soil was treated with different amounts of NADF and base oil at a rate of 800, 8,000 and 16,000 mg kg⁻¹. Initially, reduction in dehydrogenase activity was observed, but it increased with the incubation time. On the 60th day of incubation dehydrogenase activity in untreated control was 1.04 mg TPF g⁻¹ h⁻¹ whereas in the soil samples treated with NADF and the base oil (16,000 mg kg⁻¹), the activity was 1.53 mg TPF h⁻¹ and 1.90 mg TPF h⁻¹, respectively, which was 72 and 82% more than in untreated control. Base oil-treated soil showed more dehydrogenase activity than that observed with NADF. Both NADF and base oil stimulated the soil dehydrogenase activity.     

Inelastic seismic response of one-storey,asymmetric-plan systems: Effects of stiffness and strength distribution

The effects of plan-wise distribution of stiffness and strength-as determined by the number, location, orientation and yield deformations of resisting elements-on the inelastic response of one-storey systems are evaluated. In particular, various systems are investigated for wide ranges of parameters involved, with the objective of establishing how the response is influenced by: (i) the presence of resisting elements perpendicular to the direction of ground motion; (ii) the number of resisting elements along the direction of ground motion; (iii) the overstrength typical of code-designed buildings; (iv) the relative values of strength and stiffness eccentricities; and (v) whether the asymmetry of the system is due to eccentricity in stiffness or in mass. The results presented for a simple excitation make it possible to explain the inconsistencies in conclusions from various earlier investigations, and to evaluate their applicability to actual buildings.     

Undrained Triaxial Behavior of Cement Treated Marine Clay

Clays treated with lower cement contents often exhibit behaviour similar to stiff clays with planar failure surface under triaxial compression. In the present work the behaviour of a marine clay treated with 5 % cement, subjected to undrained triaxial compression tests is studied. The pre-consolidation pressure of the cemented clay due to the cementation bonding is observed to be very high. It is attempted to model the behaviour of cement treated clay using a bounding surface plasticity formulation as the plastic behaviour of the cemented clays within the yield surface has to be considered. The effect of cementation is included in the model as the pre-consolidation pressure obtained from consolidation tests. The tensile strength due to cementation bonds is included in the equation of the bounding surface. Simulations of the undrained triaxial compression tests on cemented clays are carried out and the results are validated with the experimental results.     

Safety Concerns of Ancient Temple due to Blasting in Adjacent Mines

Directives from the Hon’ble Supreme Court of India led to the banning of mining activities within a radius of 2 km of the Sri Jambunatheswara ancient temple in Hospet taluk of Karnataka State of India. On recommendation of the Department of Archaeology & Museums, Government of Karnataka, CSIR-CIMFR undertook extensive investigations wherein the ground vibration and air overpressure due to blasting in nearby iron ore mines were monitored to assess their damage and annoyance potentials. The magnitudes of blast-induced ground vibration and air-overpressure recorded in the temple were found to be within the standard safe limits stipulated by the Directorate General of Mines Safety, India when trial blasts were carried out at a distance greater than 290 m from the temple. When blasts were conducted at a distance of beyond 845 m from the temple, neither vibration nor sound of blasting could be recorded or heard at the temple premises, indicating it a safe zone for blasting. After thorough analyses of the recorded data, precise blast design parameters were recommended for blasting at distances beyond 200 m from the temple and allowing this distance to be demarcated as the safe zone where controlled blasting could ensure safety of the ancient temple.     

3D building model-assisted snapshot positioning algorithm

GPS Solutions - A method for constructively using non-line-of-sight GNSS signals from a snapshot of signal samples for positioning of users in urban areas is presented here. Using a 3D building...     

Properties of filaments in solar cycle 20-23 from McIntosh Archive

A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection(CME), which has an adverse effect on space weather. Hence,research on filaments has attracted much attention in the recent past. The tilt angle of active region(AR)magnetic bipoles is a crucial parameter in the context of the solar dynamo, which governs the conversion efficiency of the toroidal magnetic field to poloidal magnetic field. Filaments always form over polarity inversion lines(PILs), so the study of tilt angles for these filaments can provide valuable information about generation of a magnetic field in the Sun. We investigate the tilt angles of filaments and other properties using McIntosh Archive data. We fit a straight line to each filament to estimate its tilt angle. We examine the variation of mean tilt angle with time. The latitude distribution of positive tilt angle filaments and negative tilt angle filaments reveals that there is a dominance of positive tilt angle filaments in the southern hemisphere and negative tilt angle filaments dominate in the northern hemisphere. We study the variation of the mean tilt angle for low and high latitudes separately. Investigations of temporal variation with filament number indicate that total filament number and low latitude filament number vary cyclically, in phase with the solar cycle. There are fewer filaments at high latitudes and they also show a cyclic pattern in temporal variation. We also study the north-south asymmetry of filaments with different latitude criteria.