Statistical Analysis of Long Term Trends of Rainfall During 1901–2002 at Assam,India

Rainfall is a principal element of the hydrological cycle and its variability is important from both the scientific as well as socio-economic point of view. This study presents an analysis based on the precipitation variation in Assam, India over 102 years from 1901 to 2002. Precipitation data from 21 stations have been collected. These data have been analyzed for both annual and seasonal variation. For trend analysis, Mann-Kendell and Sen’s slope estimator test were used. To compare seasonal variations, three seasons of winter, summer and monsoon have been considered. Mean annual precipitation varied from 2,074 mm (at Tinsukia) to 3,538 mm (at North Chahar Hills). The most probable year of change was 1959 in annual precipitation. Time series of the Standardized Precipitation Index (SPI) depict that near normal occurs in about 68 years out 102 years, and in 2.48 years out of 102 years there was an extreme wet. All these findings can help provide rational regulatory and policy in relation to water resources to maintain the health of the various ecosystems that make up Assam, India.     

Evaluation of Optimal River Training Work Using GA Based Linked Simulation-Optimization Approach

Use of structural measures for controlling a river to minimize its devastating effect and to utilize it for the benefit of mankind is a common practice all over the world. Because of high investment, such measures require prior investigation through model study. As lab based physical model study is very expensive and time consuming, mathematical modeling is generally used for investigating different alternatives of river training works. In this study, a new approach is proposed for deciding appropriate river training measure in a particular reach of a river or channel. In this methodology, an optimization model is linked with the hydrodynamic model for obtaining cost effective combination of groynes which will maintain a user defined flow speed in a pre-decided portion of a river reach. The optimization model is developed using binary coded Genetic Algorithm (GA) and the flow simulation model uses the Beam and Warming scheme for solving the two dimensional (2D) hydrodynamic equations of unsteady flow. The performance of the model is tested by applying the methodology in a rectangular channel for attaining different target speed values at a pre-defined portion of the channel and logical results have been obtained for all the tested scenarios.     

Inhibition of lipase from rice (Oryza sativa) by diethyl-p-nitrophenyl phosphate

The inhibition of rice bran lipase (RBL) by diethyl-p-nitrophenyl phosphate was studied with reference to kinetics, nature of inhibition and also elucidate the effect of the inhibitor on the structure—function of the enzyme. Enzyme activity measurements shows that the inhibitor is more effective at 0.050 mM concentration of diethyl-p-nitrophenyl phosphate and the activity is 50% at this level of inhibitor concentration. The affinity of substrate for the enzyme was observed by the increase in the velocity of the reaction with increase in the substrate concentrations and double reciprocal plot indicates that the inhibition followed a competitive in nature and inhibition constant K _i is found to be 0.016 mM at pH 7.0. The decrease in apparent thermal denaturation temperature to 4 °C compared to control indicates the destabilization of enzyme in the presence of inhibitor. Fluorescence spectral measurements suggests that pronounced quenching of fluorescence intensity of RBL occurs at higher concentrations of diethyl-p-nitrophenyl phosphate and ‘K _a’ value was found to be 2.4 × 10⁴ M⁻¹ with free energy change ΔG^o—26 kJ/mol at 30 °C suggesting strong binding between the enzyme and the inhibitor with microenvironmental changes occur at the active site or in the neighbourhood of active site. The far UV-CD data suggest that there is no significant changes in the conformation of the enzyme as a result of binding of diethyl-p-nitrophenyl phosphate. These results indicate that diethyl-p-nitrophenyl phosphate is a inhibitor of RBL and binds to the enzyme in brining about inhibition without any structural alterations.     

Molecular interactions of pesticides at the soil-water interface

High-resolution magic angle spinning (HR-MAS) NMR spectroscopy combined with saturation-transfer double difference (STDD) NMR can be used to analyze the molecular-level interactions of pesticides and whole soils occurring at the soil-water interface. Here 1H HR-MAS STDD NMR has been applied to some common pesticides (trifluralin, acifluorfen, and (4-nitro-3-(trifluoromethyl) phenol) and a pesticide degradation product (1-naphthol). Results indicate that dipolar interactions, H-bonding, hydrophobic associations, and potentially pi-pi interactions are the predominant sorption mechanisms for these molecules at the soil-aqueous interface. It is evident that the physical and chemical characteristics of soil are highly influential in determining the mechanisms of pesticide sorption, as they significantly affect soil conformation. In particular, different binding mechanisms were observed for 1-naphthol in soil swollen using a buffer versus D2O, indicating that the K(oc) alone may not be enough to accurately predict the behavior of a molecule in a real soil environment. Preliminary kinetic-based studies suggest that both the swelling solvent and soil moisture content significantly influence the sequestration of trifluralin. These studies demonstrate that HR-MAS and STDD NMR are powerful and versatile tools which can be applied to expand our knowledge of the mechanistic interactions of agrochemicals at the molecular level.     

Evapotranspiration Modeling Using Different Tree Based Ensembled Machine Learning Algorithm

Water Resources Management - The present study investigates and evaluate the scope and potential of modern computing tools and techniques such as ensembled machine learning methods in estimating...     

Improving power conversion efficiency in polythiophene/fullerene-based bulk heterojunction solar cells

In the present work, we have studied photovoltaic devices fabricated from a blend of regioregular poly (3-hexlthiophene) (P3HT) and Buckminster fullerene. The solvent and composite ratio have been selected to obtain best morphology and minimum degradation. Buffer layers of poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT:PSS) at the anode and of LiF at the cathode were used to improve the device performance. It was further found that post-annealing of the devices for an optimum duration and temperature improves the solar cells, and the power conversion efficiency of the devices increases to 2.1% at AM1.5. Though the efficiency using [6,6]-phenyl C60 butyric acid methyl ester (PCBM) as the composite acceptor instead of C₆₀ can be higher, it was not used because of its very high cost as compared to C₆₀.     

Surface modification of semiconductor photoelectrode for improved solar cell performance

The investigation is focused on the synthesis of nanostructured TiO₂–CuO admixed photoelectrode and its use as a photoelectrode of high-efficiency PEC solar cells for hydrogen production. TiO₂, in the nanostructured form, has been prepared by hydrolysis of titanium(IV) isopropoxide solution. An improvement in the nanostructured TiO₂ photoelectrode carried out in the present work corresponds to admixing CuO to improve the spectral response. In the present study, photo-electrochemical (PEC) and hydrogen evolution characteristics of new types of ns-TiO₂–CuO admixed/Ti septum-based semiconductor septum photo-electrochemical (SC-SEP PEC) solar cell has been studied. The CuO admixed ns-TiO₂ exhibited a high photocurrent and photovoltage of 18.6 mA/cm² and 680 mV, respectively. The ns-TiO₂–CuO electrode exhibited a higher hydrogen gas evolution rate of 14.00 l/h m².     

Turbulent natural convection in an enclosure with localized heating from below

This study reports the results of a numerical investigation of turbulent natural convection in a square enclosure with localized heating from below and symmetrical cooling from the vertical side walls. The present study simulates the case of an accidental heat generation due to fire in a typical isolated building of a nuclear reactor or electronic components cabin. The source of fire is considered to be centrally located at the bottom wall with different heated widths, which is assumed to be either isothermal or with isoflux. For the purpose of the analysis, the source length is varied from 20 to 80% of the total width of the bottom wall. The top wall and the unheated portion of the bottom wall are considered to be adiabatic, whereas sidewalls are isothermal. Steady as well as transient forms of two-dimensional Reynolds–Averaged-Navier–Stokes equations and conservation equations of mass and energy, coupled with the Boussinesq approximation, are solved by the control volume based discretisation method employing the SIMPLE algorithm for pressure–velocity coupling. Turbulence is modeled using the standard k–ε model. Rayleigh number, Ra, based on the enclosure height is varied from 10⁸ to 10¹². Stream lines and isotherms are presented for various combinations of Ra and the heated width. A double cell flow pattern is observed with marginal loss in symmetry as Ra increases. The results are reported in the form of local and average Nusselt number on the heated floor. Correlations are developed to predict the heat transfer rates from the enclosure as a function of dimensionless heated width of the bottom wall and Ra, by least square linear regression analysis.     

Electricity consumption in G7 countries: A panel cointegration analysis of residential demand elasticities

This article applies recently developed panel unit root and panel cointegration techniques to estimate the long-run and short-run income and price elasticities for residential demand for electricity in G7 countries. The panel results indicate that in the long-run residential demand for electricity is price elastic and income inelastic. The study concludes that from an environmental perspective there is potential to use pricing policies in the G7 countries to curtail residential electricity demand, and thus curb carbon emissions, in the long run.