Development of a hard x-ray focal plane compton polarimeter: a compact polarimetric configuration with scintillators and Si photomultipliers

X-ray polarization measurement of cosmic sources provides two unique parameters namely degree and angle of polarization which can probe the emission mechanism and geometry at close vicinity of the compact objects. Specifically, the hard X-ray polarimetry is more rewarding because the sources are expected to be intrinsically highly polarized at higher energies. With the successful implementation of Hard X-ray optics in NuSTAR, it is now feasible to conceive Compton polarimeters as focal plane detectors. Such a configuration is likely to provide sensitive polarization measurements in hard X-rays with a broad energy band. We are developing a focal plane hard X-ray Compton polarimeter consisting of a plastic scintillator as active scatterer surrounded by a cylindrical array of CsI(Tl) scintillators. The scatterer is 5 mm diameter and 100 mm long plastic scintillator (BC404) viewed by normal PMT. The photons scattered by the plastic scatterer are collected by a cylindrical array of 16 CsI(Tl) scintillators (5 mm × 5 mm × 150 mm) which are read by Si Photomultiplier (SiPM). Use of the new generation SiPMs ensures the compactness of the instrument which is essential for the design of focal plane detectors. The expected sensitivity of such polarimetric configuration and complete characterization of the plastic scatterer, specially at lower energies have been discussed in [11, 13]. In this paper, we characterize the CsI(Tl) absorbers coupled to SiPM. We also present the experimental results from the fully assembled configuration of the Compton polarimeter.     

Prediction of flow rate of karstic springs using support vector machines

Complex void space structure and flow patterns in karstic aquifers render behaviour prediction of karstic springs difficult. Four support vector regression-based models are proposed to predict flow rates from two adjacent karstic springs in Greece (Mai Vryssi and Pera Vryssi). Having no accurate estimates of the groundwater flow pattern, we used four kernels: linear, polynomial, Gaussian radial basis function and exponential radial basis function (ERBF). The data used for training and testing included daily and mean monthly precipitation, and spring flow rates. The support vector machine (SVM) performance depends on hyper-parameters, which were optimized using a grid search approach. Model performance was evaluated using root mean square error and correlation coefficient. Polynomial kernel performed better for Mai Vryssi and the ERBF for Pera Vryssi. All models except one performed better for Pera Vryssi. Our models performed better than generalized regression neural network, radial basis function neural network and ARIMA models.     

Compressed History Matching: Exploiting Transform-Domain Sparsity for Regularization of Nonlinear Dynamic Data Integration Problems

In this paper, we present a new approach for estimating spatially-distributed reservoir properties from scattered nonlinear dynamic well measurements by promoting sparsity in an appropriate transform domain where the unknown properties are believed to have a sparse approximation. The method is inspired by recent advances in sparse signal reconstruction that is formalized under the celebrated compressed sensing paradigm. Here, we use a truncated low-frequency discrete cosine transform (DCT) is redundant to approximate the spatial parameters with a sparse set of coefficients that are identified and estimated using available observations while imposing sparsity on the solution. The intrinsic continuity in geological features lends itself to sparse representations using selected low frequency DCT basis elements. By recasting the inversion in the DCT domain, the problem is transformed into identification of significant basis elements and estimation of the values of their corresponding coefficients. To find these significant DCT coefficients, a relatively large number of DCT basis vectors (without any preferred orientation) are initially included in the approximation. Available measurements are combined with a sparsity-promoting penalty on the DCT coefficients to identify coefficients with significant contribution and eliminate the insignificant ones. Specifically, minimization of a least-squares objective function augmented by an l ₁-norm of DCT coefficients is used to implement this scheme. The sparsity regularization approach using the l ₁-norm minimization leads to a better-posed inverse problem that improves the non-uniqueness of the history matching solutions and promotes solutions that are, according to the prior belief, sparse in the transform domain. The approach is related to basis pursuit (BP) and least absolute selection and shrinkage operator (LASSO) methods, and it extends the application of compressed sensing to inverse modeling with nonlinear dynamic observations. While the method appears to be generally applicable for solving dynamic inverse problems involving spatially-distributed parameters with sparse representation in any linear complementary basis, in this paper its suitability is demonstrated using low frequency DCT basis and synthetic waterflooding experiments.     

Radioactivity monitoring in the vicinity of Jawalamukhi thrust NW Himalaya,India for tectonic study

Natural Hazards - This work reports radon-thoron monitoring at two depths (60 and 90 cm) and at 82 sites around Jawalamukhi thrust of NW Himalaya, India using Solid State Nuclear Track...     

Water logging and drainage Assessment in Ravi-Tawi irrigation command (J&K) using remote sensing approach

Water logging is one of the major land degradation processes that restricts the economic and efficient utilisation of soil and land resources in command areas. Since independence, various irrigation schemes, for providing water for agriculture and drinking have been taken up by Central and State agencies in India. In most of these schemes very little efforts have been made for proper drainage. Obstruction of natural drainage by way of construction of roads, railways, aerodrome, various structures, etc., causes the ponding of monsoon runoff on the upstream of the structures. Periodic monitoring of command areas helps in analysing the extent of water logging, and should help in taking suitable remedial measures. Remote sensing and GIS are powerful tools, which could be effectively used to study the dynamic behaviour of waterlogged areas. In this study, waterlogged and salt-affected areas have been estimated in the command area of Ravi-Tawi Irrigation Complex in Jammu region. About 14% of the total command area is water logged/ salt-affected. Being a new project, this area is likely to grow in future when the project runs with its installed capacity, and as the distributaries expand in the command area. Plausible causes of water logging have been discussed, and remedial measures suggested for reclaiming operations.     

Regional diversity in some aspects of Indian demography

Regional variations in the demography of India are explored using official data for the period 1971-1981. Socioeconomic and cultural determinants of such differentials, particularly female education and economic diversification, are addressed.     

Utilization of remotely sensed data for soil resource mapping and its interpretation for landuse planning of Bhiwani district,Haryana

Visual interpretation of IRS-1A LISS-II (October 1988 & Feb. 1989) FCC (spectral bands 2, 3 & 4) at 1:50,000 scale was carried out for soil resource mapping of Bhiwani district (Haryana State) covering on area of 5099 sq. kim. Based on image characteristics, element analysis (landform, vegetation & erosion) and field traverses, physiography-soil relationship was established. Major physiographic units identified in the area are: Aeolian plain, Fluvio-acolian plain, Transitional plain, Alluvial plain, Hills and Pediments. Area was divided into 34 subunits. Final physiography-soil map on 1:50,000 scale was prepared. Taxonomically, the soils of each unit were classified and are found as: In aeolian plain—Typic Torripsamments/coarse loamy, Typic Camborthios; Fluvio-aeolian plain-Aridic Ustipsamments/coarse loamy/fine loamy Typic/Udic Ustochrepts; Alluvial plain—Typic Ustipsamments/coarse loamy/fine loamy Typic/Udic Ustochrepts; Hills and Pediments—fregmental Lithic Torriorthents/Typic Torripsamments. Interpretation for each subunit was made regarding land suitability for various land utilisation types. It was found that hills and pediments, dunal ridges, dunal complexes and serub-lands are best suitable for forestry and horiculture plantations. Dunal plains and inter-dunal depressions are best suitable for gram/bajra/oilseeds/guar, very gently sloping dunal plain and low lying plain are suitable for wheat/arhar/cotton/sunflower.     

Application of remote sensing technique in the study of distribution of micronutrients in relation to landforms in the Sahibi river basin of Haryana

A study on the profile distribution of DTPA extractable iron, manganese, copper and zinc and physicochemical properties in ten delineated landforms of the Sahibi river basin of Haryana was underaken. Mean values for available Fe, Mn, Cu and Zn were 9.0, 11.6, 2.3 and 0.35 ppm, respectively. The soils of this area are potentially deficient in zinc. The soils of various landforms were adequately supplied with available Fe, Mn and Cu at present. In most of the soil pedons distribution of micronutrients did not follow any typical pattern neither with depth nor with landforms perhaps due to their weak pedogenic manifestation. Based on multiple regression analysis 68, 70, 71 and 16% of the variations in contents of available Fe, Mn, Cu and Zn, respectively were accountable to the simultaneous influence of various soil parameters studied.     

Bedrock gorges in the central mainland Kachchh: Implications for landscape evolution

Kachchh possesses a fault-controlled first-order topography and several geomorphic features indicative of active tectonics. Though coseismic neotectonic activity is believed to be the major factor in the evolution of the landscape, detailed documentation and analysis of vital landscape features like drainage characteristics, bedrock gorges and terraces are lacking. The present study is a site-specific documentation of gorges developed in the central part of the mainland Kachchh. We analyzed and interpreted four gorges occurring on either side of Katrol Hill Fault (KHF). The Khari river gorge is endowed with six levels of bedrock terraces, some of which are studded with large potholes and flutings. Since no active development of potholes is observed along the rivers in the present day hyper-arid conditions, we infer an obvious linkage of gorges to the humid phases, which provided high energy runoff for the formation of gorges and distinct bedrock terraces and associated erosional features. Development of gorges within the miliolites and incision in the fluvial deposits to the south of the KHF indicates that the gorges were formed during Early Holocene. However, ubiquitous occurrence of gorges along the streams to the south of KHF, the uniformly N40‡ E trend of the gorges, their close association with transverse faults and the short length of the exceptionally well developed Khari river gorge in the low-relief rocky plain to the north of KHF suggests an important role of neotectonic movements