Petrography and mineral chemistry of neovolcanics occurring between Pacific and Nazca Plate boundaries

Mid-Oceanic Ridge Basalt (MORB) samples collected from southern East Pacific Rise (SEPR) have been investigated. These highly phyric plagioclase basalts (HPPB) and moderately phyric plagioclase basalts (MOPB) show rare cumulate and vitrophyric textures with plagioclase (>10% as phenocryst) and abundant glass (>72%). Electron Probe Micro Analysis (EPMA) showed large compositional variations in the megacrysts as well as microcrysts of plagioclase (An₆₂ to An₈₂), olivine (Fo₇₈ to Fo₈₇), pyroxene (ferroaugite to augite) and iron oxides, mostly titaniferous magnetite. Olivine grains show high Mg# (>80%) and distinctly low in NiO (0.01–0.2%). Ferroan trevorite (NiO =16.22 and FeO_(t) =83.06) a characteristic meteoritic mineral has been identified from the olivine megacrysts of MORB, possibly attributed to Ni-enrichment, resulted from heterogeneity of the lower mantle. Wide range of An composition in plagioclase is indicative of large pressure range of crystal nucleation under decompression at a depth of ∼70 km (An₈₂) up to the ocean spreading centre. Absence of zoning observed in all the minerals present in the MORB samples, possibly attributed to unmixing and dominant fractionation process.     

Wind-driven estuarine turbidity maxima in Mandovi Estuary,central west coast of India

Systematic studies on the suspended particulate matter (SPM) measured on a seasonal cycle in the Mandovi Estuary, Goa indicate that the average concentrations of SPM at the regular station are ∼20mg/l, 5mg/l, 19mg/l and 5mg/l for June–September, October–January, February–April and May, respectively. SPM exhibits low-to-moderate correlation with rainfall indicating that SPM is also influenced by other processes. Transect stations reveal that the SPM at sea-end stations of the estuary are at least two orders of magnitude greater than those at the river-end during the monsoon. Estuarine turbidity maximum (ETM) of nearly similar magnitude occurs at the same location in two periods, interrupted by a period with very low SPM concentrations. The ETM occurring in June–September is associated with low salinities; its formation is attributed to the interactions between strong southwesterly winds (5.1–5.6ms⁻¹) and wind-induced waves and tidal currents and, dominant easterly river flow at the mouth of the estuary. The ETM occurring in February–April is associated with high salinity and is conspicuous. The strong NW and SW winds (3.2–3.7ms⁻¹) and wind-driven waves and currents seem to have acted effectively at the mouth of the estuary in developing turbidity maximum. The impact of sea breeze appears nearly same as that of trade winds and cannot be underestimated in sediment resuspension and deposition     

Response of low latitude ionosphere to the geomagnetic storm of May 30

Response of low latitude ionosphere to the geomagnetic storm of May 30, 2005 in the Indian longitude sector has been investigated by using the GPS data recorded at three stations namely, Udaipur, Hyderabad and Bengaluru. The event is noteworthy due to the fact that the Z component of interplanetary magnetic field (IMF Bz) remained southward for about 10 hours, coincident with the local day time for the Indian longitude sector, along with significantly higher values of AE and ASY-H indices. However, we neither found any evidence for the presence of long lasting storm time electric fields nor could we infer episodes of eastward-westward penetration of electric fields under steady southward IMF Bz and unsteady ring current conditions. On the storm day, the maximum enhancement in the total electron content has been found to be about 60%. The ionosonde observations also showed increased critical frequency (foF₂) and the height (h_PF₂) of the F layer. The foF₂ was enhanced by ∼60% which is consistent with the enhancement in total electron content. The slow rise and long duration enhancement of h_PF₂ and foF₂ have been attributed to the upwelling by the meridional neutral winds, caused by continuous energy inputs at higher latitudes. The poleward expansion of the equatorial ionization anomaly has also been observed on May 30. On May 31, the following day of the storm, significantly suppressed anomaly with near absence of its northern crest in the Indian longitude sector, revealed the effect of storm induced disturbance dynamo electric fields.     

Solution of Lane-Emden type equations using Bernstein operational matrix of differentiation

The purpose of this paper is to propose an efficient numerical method for solving Lane-Emden type equations arising in astrophysics using Bernstein polynomials. First Bernstein operational matrix of differentiation is derived using Bernstein polynomials and then applied to solve the linear and nonlinear differential equations of Lane-Emden type. Some illustrative examples are given to demonstrate the efficiency and validity of the proposed algorithm.     

Numerical Study of Discharge-Head Relationship of Piano Key Weirs for Low Heads

Water Resources - Piano Key Weirs (PKW) is a free-flowing weir, and an improvement over the labyrinth weir family. PKW has higher discharge for the same head as compared to other types of weirs....     

Experimental assessment and prediction of temporal scour depth around a spur dike

Spur dikes are river training structures that have been extensively used worldwide for towards enhancing flood control and the stability of embankments and riverbanks.However,scour around spur dikes can be a major problem affecting their stability and hydraulic performance.The precise computation of temporal scour depth at spur dikes is very important for the design of economical and safe spur dikes.This study focuses on experimentally assessing the temporal variation of scour depth around a vertical wall spur dike and identifying the parameters,which mostly influence spur dike performance for a channel bed surface comprised of sand-gravel mixtures.In the current study,the authors did physical experiments in a flume based study to obtain new data,aimed at deriving a new predictive model for spur dike scour and comparing its performance to others found in the literature.It was found that the dimensionless temporal scour depth variation increases with an increase in(i)the threshold velocity ratio,(ii)the densimetric Froude number of the bed surface sediment mixture,(iii)the flow shallowness(defined as the ratio of the approach flow depth,y,to the spur dike’s transverse length,l),and(iv)the flow depth-particle size ratio.It is also concluded that the temporal scour depth variation in the sediment mixture is influenced by the non-uniformity of sediment and decreases with an increase in the non-uniformity of the sediment mixture.A new mathematical model is derived for the estimation of temporal scour depths in sand-gravel sediment mixtures.The proposed equation has been calibrated and validated with the experimental data,demonstrating a good predictive capacity for the estimation of temporal scour depth evolution.     

The Armagh Observatory Meteor Camera Cluster: Overview and Status

Armagh Observatory installed a sky monitoring system consisting of two wide angle (90° × 52°) and one medium angle (52° × 35°) cameras in July 2005. The medium angle camera is part of a double station setup with a similar camera in Bangor, ∼73 km ENE of Armagh. All cameras use UFOCapture to record meteors automatically; software for off-line photometry, astrometry and double station calculations is currently being developed. The specifications of the cameras and cluster configuration are described in detail. 2425 single station meteors (1167, 861 and 806 by the medium-angle and the wide-angle cameras respectively) and 547 double station meteors were recorded during the months July 2005 to Dec 2006. About 212 double station meteors were recorded by more than one camera in the cluster. The effects of weather conditions on camera productivity are discussed. The distribution of single and double station meteor counts observed for the years 2005 and 2006 and calibrated for weather conditions are presented.     

Application of semi‐distributed hydrological model for basin level water balance of the Ken basin of Central India

In the present study, a semi‐distributed hydrological model soil and water assessment tool (SWAT) has been employed for the Ken basin of Central India to predict the water balance. The entire basin was divided into ten sub basins comprising 107 hydrological response units on the basis of unique slope, soil and land cover classes using SWAT model. Sensitivity analysis of SWAT model was performed to examine the critical input variables of the study area. For Ken basin, curve number, available water capacity, soil depth, soil evaporation compensation factor and threshold depth of water in the shallow aquifer (GWQ_MN) were found to be the most sensitive parameters. Yearly and monthly calibration (1985–1996) and validation (1997–2009) were performed using the observed discharge data of the Banda site in the Ken basin. Performance evaluation of the model was carried out using coefficient of determination, Nash–Sutcliffe efficiency, root mean square error‐observations standard deviation ratio, percent bias and index of agreement criterion. It was found that SWAT model can be successfully applied for hydrological evaluation of the Ken basin, India. The water balance analysis was carried out to evaluate water balance of the Ken basin for 25 years (1985–2009). The water balance exhibited that the average annual rainfall in the Ken basin is about 1132 mm. In this, about 23% flows out as surface run‐off, 4% as groundwater flow and about 73% as evapotranspiration. Copyright © 2013 John Wiley & Sons, Ltd.     

Applications of generalized additive model (GAM) to satellite-derived variables and fishery data for prediction of fishery resources distributions in the Arabian Sea

This study aims to illustrate how remotely sensed oceanic variables and fishing operations data can be used to predict suitable habitat of fishery resources in Geographic Information System. We used sea surface height anomaly (SSHa), sea surface temperature (SST), chlorophyll concentration (CC), photosynthetically active radiation (PAR) and fishing depth as predictor variables. Fishery data of Indian squid (Loligo spp.) and catfish (Tachysurus spp.) for study period (1998–2004) were segregated randomly to create training and validation. Catch was normalized into Catch per unit Effort (kg h^?1). Generalized additive modelling was performed on training data and then tested on validation data. Suitable ranges of SST, CC, SSHa and PAR for different species distributions were derived and integrated to predict their spatial distributions. Results indicated good match between predicted and actual catch. Monthly probability maps of predicted habitat areas coincide with high catch of the particular month for the study period.