Behaviour of square footing on sand reinforced with coir geocell

The use of geosynthetics as a ground improvement technique offers the advantages such as space saving, environmental sensitivity, material availability, technical superiority, higher cost savings and less construction time. Coir geotextiles can be considered as an efficient replacement to its synthetic counterparts due to its economy and excellent engineering properties. The present study aims at exploring the possibilities of utilising coir geocells as a potential reinforcement material for shallow foundations and thereby increasing the load carrying capacity of soil. Geocells were fabricated from coir geotextiles with the aim of providing an additional confinement to the soil. An enumerated parametric study was conducted by varying the relative density, depth of the first layer, width and height of coir geocell. The surface displacement profiles of the non-reinforced and coir geocell-reinforced soil indicate that the footing rotation and heave are considerably reduced with the provision of geocell. The results of the relative density study indicate that bearing capacity characteristics increase with denseness of the soil sample. It was also observed that geocell arrangement and configuration play a pivotal role in the performance characteristics of reinforced soil.     

Investigating CO<Subscript>2</Subscript>-enhanced oil recovery potential for a mature oil field: a case study based on Ankleshwar oil field,Cambay Basin,India

CO₂-enhanced oil recovery (EOR) is an upcoming technology in India. At present, no Indian field is under CO₂-EOR and implementation of this technique to a mature oil field needs a rigorous study. In the present work, we made an attempt to investigate the CO₂-EOR potential of a mature oil field, situated in Cambay Basin, India. The field was put on production in 1961, and it has produced approximately 65.36 MMt oil during massive water flooding, leading to residual oil reserves of 6.49 MMt. The operator of the field is interested in incremental oil recovery from this field by injecting CO₂. This requires estimation of incremental oil recovery potential of the field by carrying out systematic study. We, therefore, developed a conceptual model inspired by Ankleshwar oil field of Cambay Basin using available information provided by the field operator and carried out systematic studies to establish an optimized strategy for CO₂ injection. To achieve this goal, we investigated the effect of various operational parameters on oil recovery efficiency of our conceptual model and selected optimum parameters for reservoir simulations. Simulation results clearly indicate that the field can be a good candidate for CO₂-EOR, and an additional oil recovery of 10.4% of hydrocarbon pore volume is feasible. Major outcome of the study is an optimized black-oil simulation model, which is in good agreement with the fine grid compositional model of high accuracy. The proposed black-oil model can easily be implemented and updated compared with compute intensive finer compositional simulation model.     

Response of arid northeast Mexico to global climate changes during the late Pleistocene to the middle Holocene

Anthropogenic global warming might cause expansion of the drylands and trigger socio-economic challenges in the water-deficit subtropical regions. Changes in hydroclimate during the intervals of variable global temperature over the recent geological past, however, could provide useful information about the possible responses of these arid ecosystems to the near future warmer conditions. We evaluated hydroclimates of two different parts of subtropical North America by generating new records of surface processes and regional vegetation from drought-prone northeast Mexico and subsequently compared them with the paleoclimate of the central-southern United States. Our study suggests that congruent changes occurred in both parts during ~13.5–9.5 cal ka BP, an interval with no warm pool in the northern Gulf of Mexico. The precipitation and erosion responded to temperature-modulated variations in positions of the Inter-Tropical Convergence Zone (ITCZ). Conditions were wetter than today in the subsequent warmer interval (~9.5–8.2 cal ka BP) with generally stable ITCZ and the highest summer insolation. Hydroclimate changes of both parts lacked congruency during ~8.2–6.8 cal ka BP as the northern Gulf of Mexico began hosting a warm pool. Similar to the modern conditions, this warm pool might have modified trajectories of the tropical storms. Erosion and abundance of C₃ plants decreased in northeast Mexico. Higher wetness in the Mississippi River Basin and the southern Great Plains during this interval suggested that the storms made landfall more frequently in the central-southern United States. © 2019 John Wiley & Sons, Ltd.     

A Search for Periodicities in F10.7 Solar Radio Flux Data

The radio frequency emission at 10.7 cm (or 2800 MHz) wavelength (considered as solar flux density) out of different possible wavelengths is usually selected to identify periodicities because of its high correlation with solar extreme ultraviolet radiation as well as its complete and long observational record other than sunspot related indices. The solar radio flux at 10.7 cm wavelength plays a very valuable role for forecasting the space weather because it is originated from lower corona and chromospheres region of the Sun. Also, solar radio flux is a magnificent indicator of major solar activity. Here in the present work the solar radio flux data from 1965 to 2014 observed at the Domimion Radio Astrophysical Observatory in Penticton, British Columbiahas been processed using Date Compensated Discrete Fourier Transform (DCDFT) to identify predominant periods within the data along with their confidence levels. Also, the multi-taper method (MTM) for periodicity analysis is used to validate the observed periods. Present investigation exhibits multiperiodicity of the time series F10.7 solar radio flux data around 27, 57, 78, 127, 157, 4096 days etc. The observed periods are also compared with the periods of MgII Index data using same algorithm as MgII Index data has 99.9% correlation with F10.7 Solar Radio Flux data. It can be observed that the MgII index data exhibits similar periodicities with very high confidence levels.Present investigation also clearly indicates that the computed results are very much confining with the results obtained in different communication for the similar data of 10.7 cm Solar Radio Flux as well as for the other solar activities.

     

Groundwater prospects evaluation-based on hydrogeomorphological mapping: A case study in Kancheepuram district,Tamil Nadu

Water is the most important natural resource which forms the core of the ecological system. The advent of remote sensing has opened up new vistas in groundwater prospect evaluation, exploration and management. The role of hydrogeomorphological units in tile storage of groundwater from the Kancheepuram distict has been investigated using IRS P6 LISS-III data. The Kancheepuram district exhibits diverse hydrogeomorphological conditions where the groundwater regime is controlled mainly by topography and geology. The extent of various water prospectus zones in terms of percentage includes, maximum area, particularly the north-western, and central part which is characterized by good potential occupying about 43% of total area. The moderate potential is marked by only 35%, and is scattered along the northern and southern side of the study area, the remaining 12% is of poor prospectus, which is falling in the coastal region of the study area.     

Determination of Mercury in Thirty‐three International Stream Sediment and Soil Reference Samples by Direct Mercury Analyser

Mercury was determined in thirty‐three international stream sediment and soil reference samples (eleven Chinese soils, GSS‐1 to GSS‐11; twelve Chinese stream sediments, GSD‐1A to GSD‐12; four Canadian stream sediments STSD‐1 to STSD‐4; South African stream sediments, SARM‐42, SARM‐46 and SARM‐47; Japanese stream sediments, JSd‐1 to JSd‐3) by direct mercury analyser. Samples were taken in 500 μl quartz boats, placed in an auto sampler and processed (drying time 60 s at 300 °C; decomposition time 120 s at 850 °C; waiting time 45 s). The instrument was calibrated in the low (0‐50 ng) and high ranges (50‐500 ng) with two reference materials GSS‐5 and GXR‐2 (USGS). Using the calibration line, reference samples were analysed for Hg. The results of the determinations agreed with the recommended values of RMs in all cases except JSd‐1. The RSD calculated for the RMs was found to be within 20%. The detection limit was 1 ng g^?1.     

On the relative roles of El Nino and Indian Ocean Dipole events on the Monsoon Onset over Kerala

Interannual variations of the monsoon onset over Kerala (MOK) have been studied using data from over 60?years (1948?C2009) of NCEP/NCAR reanalysis and outgoing long-wave radiation. The sea surface temperature fields over the North Indian Ocean associated with the MOK have been examined in association with El Nino and Indian Ocean Dipole (IOD) events which originate in the Pacific and Indian Ocean, respectively. An analysis of the tropical convective maximum showed significant differences in its strength and location during the El Nino, IOD, early, normal, and delayed MOK composites. Further, we also looked into the role of the convective systems formed over the Arabian Sea and Bay of Bengal on MOK. The most significant features during early (delayed) MOK years is the abnormal persistence of westerlies (easterlies) several days prior to MOK and enhanced (suppressed) deep convection over the southeastern Arabian Sea and the southern Bay of Bengal. Moisture builds up over peninsular India several pentads prior to MOK during La Nina, negative IOD, and concurrent La Nina and negative IOD years as compared to the El Nino, positive IOD, and concurrent El Nino and positive IOD years, indicating its significant role on MOK. The monsoon Hadley cell and Walker circulations are weaker (stronger) during a delayed (early) MOK. Further, the sea surface temperature anomalies in the western Pacific are negative (positive) during delayed (early) MOK.     

Source apportionment and health risks assessment of black carbon Aerosols in an urban atmosphere in East India

Journal of Atmospheric Chemistry - Black carbon (BC) along with PM2.5 (fine particular matters) plays an important role in the assessment health effect of human beings. Winter season campaign...     

First record of three giant marine Bathynomids (Crustacea, Isopoda, Cirolanidae) from India

Three species,Bathynomus decemspinosus,B.doederleini and B.kensleyi (Crustacea,Isopoda,Cirolanidae),are reported for the first time from the Parangipettai coastal waters,Southeast coast of India.Several Trilasmis (Temnaspis) tridens (Cirripedia Thoracica,Lepadomorpha) were attached to the pleopods of some individuals.So,five bathynomid species are currently reported from India.     

Hydromorphogeology and Remote Sensing applications for groundwater exploration in agnigundala mineralised belt, Andhra Pradesh, India

Hydromorphogeological studies have been carried out around Agnigundala mineralised belt (longitude 70°.39′ - 16°.51′ and latitude 16°.2′ - 16°.15′) using remote sensing IRS-IB and SPOT data for ground water exploration. Based on erosional and depositional characters of various geomorphic units like Hills (Structural and denudational) Pediment, Buried pediment, plains and valley fills have been identified in various lithologies like granite, granite gneiss, biotite schist, phyllite,. quartzite and dolomite. The acclamations of individual geomorphic units through visual interpretation are verified from field data. The groundwater potentials of the individual geomorphologic units have been evaluated to obtain a complete hvdrogcological picture of the area. The field data have further helped in quanlifying various geomorphological units with reference to their potential for ground water occurrence.