Effectiveness of 3D Geoelectrical Resistivity Imaging using Parallel 2D Profiles

Acquisition geometry for 3D geoelectrical resistivity imaging in which apparent resistivity data of a set of parallel 2D profiles are collated to 3D dataset was evaluated. A set of parallel 2D apparent resistivity data was generated over two model structures. The models, horst and trough, simulate the geological environment of a weathered profile and refuse dump site in a crystalline basement complex respectively. The apparent resistivity data were generated for Wenner–alpha, Wenner–beta, Wenner–Schlumberger, dipole–dipole, pole–dipole and pole–pole arrays with minimum electrode separation, a (a = 2, 4, 5 and 10 m) and inter-line spacing, L (L = a, 2a, 2.5a, 4a, 5a and 10a). The 2D apparent resistivity data for each of the arrays were collated to 3D dataset and inverted using a full 3D inversion code. The 3D imaging capability and resolution of the arrays for the set of parallel 2D profiles are presented. Grid orientation effects are observed in the inversion images produced. Inter-line spacing of not greater than four times the minimum electrode separation gives reasonable inverse models. The resolution of the inverse models can be greatly improved if the 3D dataset is built by collating sets of orthogonal 2D profile

Occurrence of elevated nitrate in groundwaters of Krishna delta, India

Nitrate concentrations were measured in the groundwater samples of Krishna delta, India. The results indicate a large variation of nitrate from 10 - 135 mg/l. In 79 groundwater samples, about 39% shows high nitrate contents (>50 mg/l), which is more than the permissible limits in drinking water. In north Krishna delta 49% and in south Krishna delta 26% water samples were found to exceed the permissible limits. This study indicates that groundwater of north Krishna delta is more polluted than south. Nitrate pollution level is found more in dug wells compared to hand pumps/bore wells. In this region 49% dug wells and 31% hand pumps have exceeded the desirable limits. The possible sources for the high nitrate level in groundwater were identified as excessive utilization of nitrogenous fertilizers for agricultural purposes.Key words: Nitrate pollution, groundwater, Krishna delta, India

Effect of planting techniques and weed control treatments on growth and yield of wheat

A field experiment was conducted to study the effect of different planting techniques (conventional drill sowing at 16, 18 and 20 cm row spacing and bed planting with two and three rows in main plots) and weed control treatments (pinoxaden 50 g/ha, ready-mix (RM) of carfentrazone and metsulfuron 25 g/ha and pinoxaden 50 g/ha + RM of carfentrazone and metsulfuron 25 g/ha in subplots) on growth and productivity of wheat. The grain yield under row spacing 18 cm (53.30 q/ha), and 20 cm (52.02 q/ha), and three rows bed planting (51.96 q/ha) were recorded statistically at par with each other and significantly higher than 16 cm (49.37 q/ha) row spacing and two row bed planting (48.53 q/ha). Gross returns (Rs. 95637/ha) and net returns (Rs. 43929/ha) and B:C ratio (1.85) were record-ed higher under 18 cm row spacing compared to other planting techniques. Tank mixed application of pinoxaden 50 g/ha + RM of carfentrazone and metsulfuron 25 g/ha applied at 35 days after sowing (DAS) controlled both grassy and broad leaved weeds effectively with lower values of weed dry matter accumulation (7.67 g/ha) and produced growth parameters, yield attributes and yield (53.16 q/ha) at par with weed free treatment. In light of the results to maximise productivity, 18 cm row spacing may be practiced and tank mix application of pinoxaden (50 g/ha) + RM of carfentrazone and metsulfuron (25 g/ha) is recommended to reduce losses due to complex weed flora in wheat

Dynamics of a camphoric acid boat at the air–water interface

We report experiments on an agarose gel tablet loaded with camphoric acid (c-boat) spontaneously set into motion by surface tension gradients on the water surface. We observe three distinct modes of c-boat motion: harmonic mode where the c-boat speed oscillates sinusoidally in time, a steady mode where the c-boat maintains constant speed, and an intermittent mode where the c-boat maintains near-zero speed between sudden jumps in speed. Whereas all three modes have been separately reported before in different systems, controlled release of Camphoric Acid (CA) from the agarose gel matrix allowed the observation of all the three modes in the same system. These three modes are a result of a competition between the driving (surface tension gradients) and drag forces acting on the c-boat. Moreover we suggest that there exist two time scales corresponding to spreading of CA and boat motion and the mismatch of these two time scales give rise to the three modes in boat motion. We reproduced all the modes of motion by varying the air–water interfacial tension using Sodium Dodecyl Sulfate (SDS)

Effect of different dates of sowing on yield attributes, yield and quality of Barley (Hordeum vulgare L.) cultivars

A study was conducted during rabi2013-14 at Barley Research Area of CCS Haryana Agricultural University, Hisar with the objective to study the effect of different date of sowing on growth, yield and quality characters of barley cultivars. The experiment was laid out in a split plot design with five date of sowing (30th October, 10th, 20th, 30th November and 10th December) in main plots and four cultivars (BH 902, RD 2552, DWRUB 52 and RD 2668) kept in sub plots replicated thrice. Crop sown on 30th October produced significantly higher values of growth parameters, yield attributes (115 productive tillers per meter row length, no. of grains per spike- 37 and test weight -46.90) and yield (grain yield- 4733 kg ha-1 and straw yield- 8368 kg ha-1). But it was statistically at par with 10th November sowing date. Grain protein content, hectoliter weight and bold grains percentage decreased significantly with delay in sowing while malt content percentage was recorded significantly higher (89.53%) in 10th December date of sowing. Among the cultivars DWRUB 52 produced significantly higher grain yield (4516 kg ha-1) and quality attributes like malt content (86.25%) than other cultivars

Prediction of Storage Life of Propellants having Different Burning Rates using Dynamic Mechanical Analysis

Propellants, visco-elastic in nature, show time and temperature dependent behaviour on deformation. Hence, the time–temperature superposition principle may be applied to the visco-elastic properties of propellants. In the present study, dynamic mechanical analyser (DMA) was used to evaluate the dynamic mechanical properties and quantify the storage life of four different propellants based on hydroxyl terminated polybutadiene, aluminium and ammonium perchlorate having different burning rates ranging from 5 mm/s to 25 mm/s. Each sample was given a multi-frequency strain of 0.01 per cent at three discrete frequencies (3.5 Hz, 11 Hz, 35 Hz) in the temperature range - 80 °C to + 80 °C. The storage modulus, loss modulus, tan delta and glass transition temperature (Tg) for each propellant samples have been evaluated and it is observed that all the propellants have shown time (frequency) and temperature dependent behaviour on deformation. A comparison of the log aT versus temperature curves (where aT is horizontal (or time) shift factor) for all four propellants indicate conformance to the Williams–Landel–Ferry (WLF) equation. The master curves of storage modulus (log É versus log ω plots) were generated for each propellant. A plot of É versus time for all propellants was generated up to 3 years, 6 years, and 10 years of time, respectively. The drop in the storage modulus below the acceptable limit with time may be used to predict the shelf life of the propellant.Defence Science Journal, 2012, 62(5), pp.290-294, DOI:http://dx.doi.org/10.14429/dsj.62.248