Analytical investigations on loop-manoeuvre of underwater towed cable-array system

The paper reports on analytical case studies on the loop manoeuvre of an underwater towed cable-array system to give an insight into the tactical aspects of their naval applications. The analytical formulation and the solution procedure adopted for this three dimensional dynamic problem is also described. The case studies have been carried out for different loop radii, tow lengths, tow speeds and truncated loops. The resulting X,Y,Z co-ordinates of the towed cable-array and tow-point tensions have been computed. Based on these results, the tow-length to loop radii ratio, leading to cable-array system looping, has been found. The values of speed reduction and turning radius, causing dangerous relaxation in tow-point tension have been worked out. After exit from the loop, the timing required for realignment of the cable-array system with the ship's heading can be obtained from plots of the results. These timings help to plan ship manoeuvres to optimise reestablishment of stable listening conditions during underwater surveillance.     

Assessment of groundwater potential zone using remote sensing,GIS and multi criteria decision analysis techniques

The sustainable development and management of groundwater resource needs quantitative assessment, based on scientific principle and recent techniques. In the present study, groundwater potential zone is being determined using remote sensing, Geographical Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) techniques using various thematic layers viz. geomorphology, geology, drainage density, slope, rainfall, soil texture, groundwater depth, soil depth, lineament and land use/ land cover. The Analytic Hierarchy Approach (AHP) is used to determine the weights of various themes for identifying the groundwater potential zone based on weights assignment and normalization with respect to the relative contribution of the different themes to groundwater occurrence. Finally, obtained groundwater potential zones were classified into five categories, viz. low, medium, medium-high, high and very high potential zone. The result depicts the groundwater potential zone in the study area and found to be helpful in better development and management planning of groundwater resource.     

Construction and Characterization of Transportable Calibration Pads for Calibration of Portable and Airborne Gamma Ray Spectrometers in India

Characterization of the Panandhro lignite deposits from western Indian state of Gujarat, based on the geochemical and palynological evidences, has been performed to assess the floral composition, maturity and hydrocarbon potential of the sequence. Elementally, the lignites consist of moderate carbon, low hydrogen and moderate sulfur contents. The samples are characterized by high TOC contents (lignite: av. 46.43 wt.%, resin: 62.47 wt.%). The average HI values for the lignite is 136 mg HC/g TOC, and that of the associated resin is 671 mg HC/g TOC. The highest T_max is recoded in lignite (422°C) and lowest in the resin (39°C) samples. The FTIR spectrum of lignite is characterized by highly intense OH stretching peak ~3350 cm^-1, aliphatic CH_x stretching peaks between 3000-2800 cm^-1, aromatic C=O stretching and an aromatic C=C stretching. The spectrum of resin shows strongest absorption due to aliphatic CHx stretching between 2940-2915 cm^-1 and 2870-2850 cm^-1, and deformation by the medium peak between 1450 and 1650 cm^-1. The recovered palynofloral assemblage indicates the dominance of angiosperm pollen grains with maximum abundance of Arecaceae family, and subdominant pteridophytic spores. Marine influence is indicated by the presence of abundant dinoflagellate cysts. The occurrence of flora from a variety of ecological niches suggests a luxuriant diverse vegetation pattern existed in the vicinity of depositional site under humid tropical conditions. The overall characteristics of the lignite deposits point towards their ability to generate (upon maturation) hydrocarbons as they have types III–II admixed kerogen (organic matters).     

Comparison of AMSR-2 wind speed and sea surface temperature with moored buoy observations over the Northern Indian Ocean

The Northern Indian Ocean (NIO) is unique due to seasonal reversal of wind patterns, the formation of vortices and eddies which make satellite observations arduous. The veracity of sea surface wind (SSW) and sea surface temperature (SST) products of sun-synchronous AMSR-2 satellite are compared with high-temporal moored buoy observations over the NIO. The two year-long (2013–2014) comparisons reveal that the root-mean-square-error (RMSE) of AMSR-2 SST and SSW is \(<0.4{^{\circ }}\hbox {C}\) and \(<1.5\hbox { ms}^{-1}\), respectively, which are within the error range prescribed for the AMSR-2 satellite (\(\pm 0.8{^{\circ }}\hbox {C}\), \(\pm 1.5\hbox { ms}^{-1})\). The SST–wind relation is analyzed using data both from the buoy and satellite. As a result, the low-SST is associated with low-wind condition (positive slope) in the northern part of the Bay of Bengal (BoB), while low SST values are associated with high wind conditions (negative slope) over the southern BoB. Moreover, the AMSR-2 displayed larger slope for SST–wind relation and could be mainly due to overestimation of SST and underestimation of wind as compared to the buoy. The AMSR-2 SSW exhibited higher error during post-monsoon followed by monsoon season and could be attributed to the high wind conditions associated with intense oceanic vortices. The study suggests that the AMSR-2 products are reliable and can be used in tropical air–sea interactions, meso-scale features, and weather and climate studies.     

Early Cambrian Ichnofossils from the Mussoorie Syncline and revision of Trace Fossil Biozonation of the Lesser Himalaya,India

A new locality bearing ichnofossils of the Cruziana Assemblage Zone-Ⅲ from the Mussoorie syncline,Lesser Himalaya,is located in rocks of Member-B of the Dhaulagiri Formation,Tal Group,exposed along the Maldewta-Chhimoli fresh road cut section.The site yielded ichnofossils Bergaueria perata,Cochlichnus anguineus,？Diplocraterion isp.,Dimorphichnus obliquus,diplichnitiform Cruziana bonariensis,Diplichnites gouldi,Glockeria isp.,Helminthopsis isp.,Monomorphichnus lineatus,Phycodes palmatum,Palaeophycus striatus,Planolites beverleyensis,Planolites montanus,Treptichnus cf.T.pedum,scratch marks and an undetermined worm impression.An Early Cambrian age （Cambrian Series 2） is assigned to the ichnofossil-bearing strata based on the stratigraphic position between the Drepanuroides and Palaeoolenus trilobite zones.A revised Cambrian ichnofossil zonation is presented for the Tal Group of the Mussoorie syncline.Together with their occurrence on rippled surfaces,and the lateral displacement of some trackways （due to current action）,a sub-aqueous shallow-marine depositional setting is proposed for the rocks of Member-B.     

Gauribidanur Low-Frequency Solar Spectrograph

A new radio spectrograph, dedicated to observe the Sun, has been recently commissioned by the Indian Institute of Astrophysics (IIA) at the Gauribidanur Radio Observatory, about 100 km North of Bangalore. The instrument, called the Gauribidanur Low-frequency Solar Spectrograph (GLOSS), operates in the frequency range≈40?–?440 MHz. Radio emission in this frequency range originates close to the Sun, typically in the radial distance range r≈1.1?–?2.0 R_⊙. This article describes the characteristics of the GLOSS and the first results.     

Rhodophycean algae from the Lower Cretaceous of the Cauvery Basin,South India

The present paper records eight Rhodophycean taxa from the Kallakudi limestone of the Uttatur Group (Lower Cretaceous) exposed in the quarries at Kallakudi and Olaipadi near Govindarajapatnam of the Cauvery Basin, south India. Of these, four species (Melobesioideae gen. et sp. indet 1, Melobesioideae gen. et sp. indet 2, Lithophyllum alternicellum and Pseudoamphiroa propria) belong to corallinaceae family, one species (Polystrata alba) is assigned to Peyssonneliaceae family, two species (Solenopora urgoniana and Parachaetetes asvapatii) are placed under Solenoporaceae; and one species (Sporolithon sp.) is referable to Sporolithaceae family. Among these, three taxa (Solenopora urgoniana, Lithophyllum alternicellum and Pseudoamphiroa propria) are recorded for the first time from India. The study also includes observations on ultrastructural morphological features of Parachaetetes asvapatii. The observations reveal absence of cell fusions, which confirms its affinities with Solenoporaceae. Palaeoecological data indicate that the assemblage from the sequence at the Kallakudi quarry is characteristic of lagoonal to reefal environment, whereas the Olaipadi quarry sequence near Govindarajapatnam points to 20 m to 30 m deep environment characterized by high- to moderate energy conditions.     

Planetary waves in the mesosphere lower thermosphere during stratospheric sudden warming: observations using a network of meteor radars from high to equatorial latitudes

Climate Dynamics - In the present communication, characteristics of mean winds and planetary waves in the mesosphere lower thermosphere (MLT) region during sudden stratospheric warming (SSW) events...     

A Comprehensive Review on Microalgae-Based Biorefinery as Two-Way Source of Wastewater Treatment and Bioresource Recovery

In the past few years, microalgae have gained huge recognition from the scientific community due to their potential applications in the production of a broad array of bio-based products varying from biofuels to nanoparticles. Due to their elevated growth rate, high tolerance to various types of abiotic stresses, and complex metabolic capacity, microalgae can be used as promising tools for the attainment of a circular bioeconomy. Moreover, they can simply utilize nutrients from wastewater for biorefinery purposes, resulting in resource recovery coupled with wastewater treatment. However, due to their sub-optimal yields and high production costs, microalgae-based bio-products have not yet been commercialized. This review provides insights into the employment of microalgae as an efficient bioresource for the treatment of wastewater with simultaneous enactment as a biorefinery to produce biofuels, biochar, bioplastic, fertilizers, and other high-value bioproducts. Furthermore, the application of microalgal nanoparticles in wastewater treatment and prospects for genetic modification of microalgae for enhanced biorefinery capabilities have also been briefly highlighted.     

MST radar investigation on inertia-gravity waves associated with tropical depression in the upper troposphere and lower stratosphere over Gadanki (13.5°N, 79.2°E)

Continuous measurements of 3-dimensional winds, spectral parameters, and tropopause height for ～114 h during the passage of a tropical depression using mesosphere–stratosphere–troposphere (MST) radar at Gadanki (13.5°N, 79.2°E) are discussed. The spectral analysis of zonal and meridional winds shows the presence of inertia-gravity wave (IGW) with the dominant periodicity of 56 h and intrinsic period of 27 h in the upper troposphere and lower stratosphere (UTLS). The strengthening of easterly jet and associated wind shears during the passage of the depression is one of the causative mechanisms for exciting the IGW. A well-established radar method is used to identify the tropopause and to study its response to the propagating atmospheric disturbances. The significance of the present study lies in showing the response of tropopause height to the IGW during tropical depression for the first time, which will have implications in stratosphere–troposphere exchange processes.