Harnessing the sun for an evergreen revolution: a study of solar-powered irrigation in Bihar,India

In 2012, the government of Bihar revived 34 non-functioning public tubewells using solar panels. The performance of 16 of these wells over 12 months was tracked and analyzed using data from tubewell operators and 240 farmers. Access to affordable irrigation from solar pumps led to a 9–10% increase in productivity of rice and wheat. Furthermore, in a severe drought, farmers could grow paddy in the entire area irrigated by solar pumps, when nearly 40% of other land was left fallow. Solar pumps can help increase crop productivity, reduce the cost of irrigation, and make agriculture more resilient to climate change.     

An analysis of surface erosion in electrical discharge machining

An analytical model for the computation of metal erosion by a single spark in electrical discharge machining is presented. The effect of plasma channel growth on metal removal was examined and good correlation was found between theoretical and experimental results. The model was further developed to study the effects of non-rectangular current pulse shapes on metal removal and relative electrode wear to establish the optimum current pulse form required to minimize relative electrode wear.     

Analysis of startup oscillations in natural circulation boiling systems

The aim of the present work is to get an insight of the phenomena behind the low-pressure low-power transients that occur during startup of a natural circulation boiling system. A RELAP5 model developed for a test facility and its prototype is used to record additional system parameters that were not included in the data obtained from experiments. The flow oscillations observed during experimental and numerical studies are analyzed and classified. It is inferred that the low amplitude oscillations are not condensation induced geysering instabilities, but a density wave instability supported by flashing. The similarity between the nature of startup transients observed in the test facility and the prototype is also examined. The effect of flashing is more pronounced in the prototype due to the strong variation of saturation temperature as the length scale is 4 times that of the model. The time series data obtained from experimental observations and numerical simulations are analyzed to identify the structural nature of flow oscillations. The power spectral density estimated using fast Fourier transform (FFT) algorithm illustrates the chaotic nature of the signals. The nonlinear time series analysis (TISEAN) package has been used for the estimation of Lyapunov exponent and the Poincaré section. The Poincaré section and the Lyapunov exponent confirm the chaotic nature of the flow oscillations.     

Dielectric relaxation studies on [PEO–SiO<Subscript>2</Subscript>]:NH<Subscript>4</Subscript>SCN nanocomposite polymer electrolyte films

Present work deals with findings on dielectric relaxation behaviour and a.c. conduction in a SiO₂-doped polymer nanocomposite electrolyte system, namely, [(100 − x)PEO + xSiO₂]:yNH₄SCN. The formation of nanocomposite has been ascertained by XRD measurements. The effect of salt and filler (SiO₂) on conductivity response of PEO-based nanocomposite polymer electrolyte has been investigated by impedance spectroscopy. The variation of dielectric permittivity, dielectric loss and modulus spectra with frequency and temperature was carried out from impedance spectroscopy data. The a.c. conductivity seems to follow the universal power law.     

Attenuation of ultrasonic waves in V, Nb and Ta at low temperatures

Variation of ultrasonic attenuation and velocities with temperature have been evaluated in the temperature range 5-50 K due to electron-phonon interaction mechanism in transition metals vanadium, niobium and tantalum for longitudinal and shear waves. For this evaluation, we have also computed the second order elastic constants using Morse potential. Behaviour of acoustical phonons in these bcc metals is different from other normal metals, intermetallics, semimetallics and alloys. Some characteristic features of these materials connected to ultrasonic parameters are discussed.     

Selection of metal salts for alkaline phosphatase production using response surface methodology

Response surface methodology was used to optimize the concentration of important metal salts screened by Placket–Burman design. Eight metal salts such as CaCl₂, CoCl₂, CuSO₄, FeCl₃, MgSO₄, MnSO₄, NaCl and Pb(NO₃)₂ were tested by using Placket–Burman design criterion and four salts viz. CaCl₂, MgSO₄, MnSO₄ and NaCl showed significant effect (P < 0.05) on alkaline phosphatase production. The metal salts concentration was optimized by applying central composite design (CCD) and the most suitable metal salts composition for alkaline phosphatase production in 100 ml medium was CaCl₂ – 0.083 g; MgSO₄ – 0.041 g; MnSO₄ – 0.037 g and NaCl – 0.34 g. At these optimum levels of metal salts, alkaline phosphatase production of 2778.92 U/ml was obtained. 1.53-fold increase in the alkaline phosphatase yield was observed after selection and optimization of metal salts for alkaline phosphatase production by response surface methodology.     

An Unbiased Method for Probabilistic Fire Safety Engineering,Requiring a Limited Number of Model Evaluations

The rise of Performance Based Design methodologies for fire safety engineering has increased the interest of the fire safety community in the concepts of risk and reliability. Practical applications have however been severely hampered by the lack of an efficient unbiased calculation methodology. This is because on the one hand, the distribution types of model output variables in fire safety engineering are not known and traditional distribution types as for example the normal and lognormal distribution may result in unsafe approximations. Therefore unbiased methods must be applied which make no (implicit) assumptions on the PDF type. Traditionally these unbiased methods are based on Monte Carlo simulations. On the other hand, Monte Carlo simulations require a large number of model evaluations and are therefore too computationally expensive when large and nonlinear calculation models are applied, as is common in fire safety engineering. The methodology presented in this paper avoids this deadlock by making an unbiased estimate of the PDF based on only a very limited number of model evaluations. The methodology is known as the Maximum Entropy Multiplicative Dimensional Reduction Method (ME-MDRM) and results in a mathematical formula for the probability density function (PDF) describing the uncertain output variable. The method can be applied with existing models and calculation tools and allows for a parallelization of model evaluations. The example applications given in the paper stem from the field of structural fire safety and illustrate the excellent performance of the method for probabilistic structural fire safety engineering. The ME-MDRM can however be considered applicable to other types of engineering models as well.     

Geospatial technology applied to spatiotemporal assessment of Harike Wetland,Punjab

The Harike Wetland situated in Punjab is a Ramsar site and a wetland of national importance. The present study was undertaken to assess the spatiotemporal dynamics of the wetland on the basis of geospatial technology and ground‐based studies. Landsat images for the years 2002 and 2014 were acquired from the United States Geological Survey and classified digitally to generate landuse/land cover maps involving four classes (water, grassland (including water hyacinth), agriculture, built‐up (settlement), barren land). The total area of the Harike Wetland was found to be 8023.68 ha. Water sampling at eleven sites was carried out and evaluated for physicochemical parameters. The water quality at several sampling points was found to be severely degraded. Change detection analysis revealed the submerged area (area under water) and grassland (including water hyacinth) had decreased over the past 12 years, whereas that area under agriculture and built‐up land has increased, indicating a shrinkage in the total wetland area. The present study also indicated that the near‐infrared band is a good indicator of water quality parameters, as indicated by the significant positive correlation between the near‐infrared band and relevant water parameters. Because the wetland is important from both an ecological perspective and economic perspective, regular monitoring is recommended, for which geospatial technology has proven to be very useful.     

Studies on chemically modified cotton. V. Effect of zinc chloride solutions on swelling and other properties of cotton

This paper describes the effect of zinc chloride solutions of different molarity at different temperatures, viz., 10°, 25°, 36°, 55°, and 75°C, on various properties of cotton fiber such as degree of swelling, accessibility to water vapor and iodine absorption, infrared ratio, barium activity number (BAN), and leveling-off degree of polymerization (LODP). Zinc chloride solution caused inter- and intrafibrillar swelling in cotton fiber depending on conditions of treatment, viz., concentration of solution and temperature employed. Fibers treated in 10.07 moles/1. (M) solution of zinc chloride in slack state showed rapid increase in degree of swelling up to 2 hr, followed by a slow increase, reaching the maximum after 3 hr of treatment. Fibers swollen with fixed ends without allowing shrinkage showed gradual increase with maximum swelling after 6 hr of treatment. Cotton fibers treated in different molar solutions of zinc chloride at 55°C showed varying degrees of swelling (inter- and intrafibrillar) and a somewhat different trend compared to that observed at 10°C. Electron micrographs revealed mostly intercrystalline swelling in case of samples treated with 9.26M at 10°C, while the same concentration produced intracrystalline swelling at 55°C. Accessibility to water vapor, iodine absorption, and BAN of treated samples showed specific effect of temperature with regard to effectiveness of concentrations of zinc chloride solutions. Similar effects of temperature with regard to concentrations of reagent were observed on infrared ratio and LODP. Accessibility by iodine absorption and LODP correlate with BAN; also, the accessibility by iodine absorption correlates with the LODP.