Systems Analysis of Tank Irrigation: II. Delayed Start and Water Deficit

Tank irrigation systems in the semiarid regions of India are discussed in this paper. To optimize the grain yield of rice, it is essential to start the agricultural operations in the second week of July so that favorable climatic conditions will prevail during flowering and yield formation stages. Because of low inflow during the initial few weeks of the crop season, often farmers are forced to delay planting until sufficient sowing rain and inflow have occurred or to adopt deficit irrigation during this period. The delayed start affects the grain yield, but will lead to an improved irrigation efficiency. A delayed start of agricultural operations with increased irrigation efficiency leads to the energy resources becoming critical during the peak requirement week, particularly those of female labor and animal power. This necessitates augmenting these resources during weeks of their peak use, either by reorganizing the traditional methods of cultivation or by importing from outside the system.

Comparison of ANN models for predicting water quality in distribution systems

Deterministic models have been widely used to predict water quality in distribution systems, but their calibration requires extensive and accurate data sets for numerous parameters. In this study, alternative data-driven modeling approaches based on artificial neural networks (ANNs) were used to predict temporal variations of two important characteristics of water quality chlorine residual and biomass concentrations. The authors considered three types of ANN algorithms. Of these, the Levenberg-Marquardt algorithm provided the best results in predicting residual chlorine and biomass with error-free and ``noisy'' data. The ANN models developed here can generate water quality scenarios of piped systems in real time to help utilities determine weak points of low chlorine residual and high biomass concentration and select optimum remedial strategies.

Potential-distance relationships of clay-water systems considering the Stern theory

This paper deals with the use of Stem theory as applied to a clay-water electrolyte system, which is more realistic to understand the force system at micro level man the Gouy-Chapman theory. The influence of the Stern layer on potential-distance relationship has been presented quantitatively for certain specified clay-water systems and the results are compared with the Gouy-Chapman model. A detailed parametric study concerning the number of adsorption spots on the clay platelet, the thickness of the Stern layer, specific adsorption potential and the value of dielectric constant of the pore fluid in the Stern layer, was carried out. This study investigates that the potential obtained at any distance using the Stern theory is higher than that obtained by the Gouy-Chapman theory. The hydrated size of the ion is found to have a significant influence on the potential-distance relationship for a given clay, pore fluid characteristics and valence of the exchangeable ion.

Sensitivity of polarization fluctuations to the nature of protein-water interactions: Study of biological water in four different protein-water systems

Since the time of Kirkwood, observed deviations in magnitude of the dielectric constant of aqueous protein solution from that of neat water (similar to 80) and slower decay of polarization have been subjects of enormous interest, controversy, and debate. Most of the common proteins have large permanent dipole moments (often more than 100 D) that can influence structure and dynamics of even distant water molecules, thereby affecting collective polarization fluctuation of the solution, which in turn can significantly alter solution's dielectric constant. Therefore, distance dependence of polarization fluctuation can provide important insight into the nature of biological water. We explore these aspects by studying aqueous solutions of four different proteins of different characteristics and varying sizes, chicken villin headpiece subdomain (HP-36), immunoglobulin binding domain protein G (GB1), hen-egg white lysozyme (LYS), and Myoglobin (MYO). We simulate fairly large systems consisting of single protein molecule and 20000-30000 water molecules (varied according to the protein size), providing a concentration in the range of similar to 2-3 mM. We find that the calculated dielectric constant of the system shows a noticeable increment in all the cases compared to that of neat water. Total dipole moment auto time correlation function of water < dM(W) (0)delta M-W (t) > is found to be sensitive to the nature of the protein. Surprisingly, dipole moment of the protein and total dipole moment of the water molecules are found to be only weakly coupled. Shellwise decomposition of water molecules around protein reveals higher density of first layer compared to the succeeding ones. We also calculate heuristic effective dielectric constant of successive layers and find that the layer adjacent to protein has much lower value (similar to 50). However, progressive layers exhibit successive increment of dielectric constant, finally reaching a value close to that of bulk 4-5 layers away. We also calculate shellwise orientational correlation function and tetrahedral order parameter to understand the local dynamics and structural re-arrangement of water. Theoretical analysis providing simple method for calculation of shellwise local dielectric constant and implication of these findings are elaborately discussed in the present work. (C) 2014 AIP Publishing LLC.

Optimal hydrothermal load flow: Formulation and a successive approximation solution for fixed head systems

This paper deals with the optimal load flow problem in a fixed-head hydrothermal electric power system. Equality constraints on the volume of water available for active power generation at the hydro plants as well as inequality constraints on the reactive power generation at the voltage controlled buses are imposed. Conditions for optimal load flow are derived and a successive approximation algorithm for solving the optimal generation schedule is developed. Computer implementation of the algorithm is discussed, and the results obtained from the computer solution of test systems are presented.

Sacrificial photolysis of water on TiO2 fine powders prepared by the hydrothermal method

The often discussed role of surface hydroxylation of TiO2 particles as an essential characterestics for their photocatalytic activity can be verified by preparing TiO2 powders by hydrothermal method since hydroxylated surface layers will be better retained on these particles formed in superheated water. Thus, fine powders of TiO2 (rutile) with high degree of crystallinity are formed from titanium oxychloride in the mixed solvent of water and 2-propanol at 160–230°C and 20–120 atm. The anatase phase is produced from the same medium when sulfate ion impurity is present, with Image . TiO2 powders are washed free of anions and 2-propanol by ultrafiltration and are Pt mounted by a photochemical method. Aqueous suspensions of both forms of TiO2 neither as such nor after Pt-loading, do not produce H2 on band gap illumination whereas, H2 is generated in presence of hole scavengers such as EDTA, TEOA, sulfite or hypophosphite. The effects of hole scavenger concentration, Pt : TiO2 ratio, particulate suspension density and the nature of hole scavengers on H2 production are presented. Platinised rutile powders are equally active as anatase in sacrificial systems.

Metallomicelles as potent catalysts for the ester hydrolysis reactions in water

Synthetic amphiphiles have been employed for the investigation of diverse topics, e.g. membrane mimetics, drug delivery, ion sensing and even in certain separation processes. Metal-complexing amphiphiles comprise an interesting class of compounds possessing multiple utilities. Upon solubilization in water they form metallomicelles. For achieving specific catalysis of a variety of reactions, metallomicelles were utilized by applying the principles of coordination chemistry and self-organizing systems. Because of their certain similarities with the natural enzymes, metallomicelles were synthesized as catalysts for many reactions. In particular the metallomicelles play a catalytic role in reactions involving the hydrolysis of activated carboxylate esters, phosphate esters and amides at ambient conditions near neutral pH. Apart from the hydrolysis reactions, these were exploited to play pertinent role as Lewis acid catalysts in cycloaddition reactions, and in other reactions such as phenolic oxidation in presence of hydrogen peroxide. In this review we emphasize with the help of assorted examples, the design, synthesis of metal-complexing amphiphiles and their aggregation behavior leading to catalytic hydrolysis reactions in aqueous media.

Comparative study of lead-acid batteries for photovoltaic stand-alone lighting systems

The lead-acid battery is often the weakest link in photovoltaic (PV) installations. Accordingly, various versions of lead-acid batteries, namely flooded, gelled, absorbent glass-mat and hybrid, have been assembled and performance tested for a PV stand-alone lighting system. The study suggests the hybrid VRLA batteries, which exhibit both the high power density of absorbent glass-mat design and the improved thermal properties of the gel design, to be appropriate for such an application. Among the VRLA-type batteries studied here water loss for the hybrid VRLA batteries is minimal and charge-acceptance during the service at high temperatures is better in relation to their AGM counterparts.

A Fair Contract for Managing Water Scarcity

In public utilities, under supply constraints, fairness considerations lead to a market failure. This paper characterizes a two-period principal-agent contract for demand management, that mitigates this market failure in urban water systems. The contract is designed as an extensive form mechanism using subgame perfect Nash equilibrium (SPNE) as the solution concept. The contract is fair; and is shown to be economically efficient if, in case of deviation by the agent, the gain to the agent and the loss to the principal are small. It is shown that the assumption can be avoided in an infinite horizon contract.

Drop formation studies in liquid—liquid systems

Benzene drops were formed in continuous media of water and glycerine of varying physical properties. The effect on drop volumes of variables like volumetric flow-rate, interfacial tension, continuous phase viscosity and capillary diameter was studied. An equation has been developed, based on a two stage drop formation mechanism, which predicts drop volumes within an average error of 7 per cent for the range of physical properties employed in this investigation.

Evaluation of solute-solvent interactions from solvent blue-shifts of n → π* transitions of C=O, C=S, NO2 and N=N groups: hydrogen bond energies of various donor-acceptor systems

Effects of non-polar, polar and proton-donating solvents on the n → π* transitions of C=O, C=S, NO2 and N=N groups have been investigated. The shifts of the absorption maxima in non-polar and polar solvents have been related to the electrostatic interactions between solute and solvent molecules, by employing the theory of McRAE. In solvents which can donate protons the solvent shifts are mainly determined by solute-solvent hydrogen bonding. Isobestic points have been found in the n → π* bonds of ethylenetrithio-carbonate in heptane-alcohol and heptane-chloroform solvent systems, indicating the existence of equilibria between the hydrogen bonded and the free species of the solute. Among the different proton-donating solvents studied water produces the largest blue-shifts. The blue-shifts in alcohols decrease in the order 2,2,2-trifluoroethanol, methanol, ethanol, isopropanol and t-butanol, the blue-shift in trifluoroethanol being nearly equal to that in water. This trend is exactly opposite to that for the self-association of alcohols. It is suggested that electron-withdrawing groups not merely decrease the extent of self-association of alcohols, but also increase the ability to donate hydrogen bonds. The approximate hydrogen-bond energies for several donor-acceptor systems have been estimated. In a series of aliphatio ketones and nitro compounds studied, the blue-shifts and consequently the hydrogen bond energies decrease with the decrease in the electron-withdrawing power of the alkyl groups. It is felt that electron-withdrawing groups render the chromophores better proton acceptors, and the alcohols better donors. A linear relationship between n → π* transition frequency and the infrared frequency of ethylenetrithiocarbonate has been found. It is concluded that stabilization of the electronic ground states of solute molecules by electrostatic and/or hydrogen-bond interactions determines the solvent shifts.

Metabolism of glycerol by an Arthrobacter species

An Arthrobacter species (tentatively identified as A. citreus), isolated by the enrichment culture method with glycerol as the sole source of carbon, was studied with a view to elucidate its pathway of glycerol breakdown. Evidence has been obtained against the functioning of the phosphorylative pathway by the study of (1) oxygen uptake with phosphorylated intermediates, (2) uptake of inorganic phosphorus by intact resting cells, (3) action of inhibitors like sodium fluoride, sodium azide, sodium arsenite, sodium iodoacetate, and parachloromercurybenzoate on oxygen uptake with resting cell suspensions and cell-free extracts in some cases. Evidence presented for the functioning of a non-phosphorylative pathway includes studies on the oxidation of glycerol, D-glyceraldehyde, glycerate, glycolic aldehyde, glycolic acid, glyoxylic acid, and formic acid to carbon dioxide and water. Further, the possibility of glyoxylate metabolism through the tricarboxylic acid cycle by its formation of malate was shown. The significance of the above pathway is that it has pointed to an alternative route of carbohydrate metabolism and entry into the tricaboxylic acid cycle without the intervention of pyruvate or the condensing enzyme.

COMMON-Sense net:Improved water management for resource-poor farmers via sensor networks

We describe the on-going design and implementation of a sensor network for agricultural management targeted at resource-poor farmers in India. Our focus on semi-arid regions led us to concentrate on water-related issues. Throughout 2004, we carried out a survey on the information needs of the population living in a cluster of villages in our study area. The results highlighted the potential that environment-related information has for the improvement of farming strategies in the face of highly variable conditions, in particular for risk management strategies (choice of crop varieties, sowing and harvest periods, prevention of pests and diseases, efficient use of irrigation water etc.). This leads us to advocate an original use of Information and Communication Technologies (ICT). We believe our demand-driven approach for the design of appropriate ICT tools that are targeted at the resource-poor to be relatively new. In order to go beyond a pure technocratic approach, we adopted an iterative, participatory methodology.

Ab initio molecular orbital calculations on ion pair-water complexes of metal halides and oxides

Ab initio MO calculations are performed on a series of ion-molecular and ion pair-molecular complexes of H2O + MX (MX = LiF, LiCl, NaCl, BeO and MgO) systems. BSSE-corrected stabilization energies, optimized geometrical parameters, internal force constants and harmonic vibrational frequencies have been evaluated for all the structures of interest. The trends observed in the geometrical parameters and other properties calculated for the mono-hydrated contact ion pair complexes parallel those computed for the complexes of the individual ions. The bifurcated structures are found to be saddle points with an imaginary frequency corresponding to the rocking mode of water molecules. The solvent-shared ion pair complexes have high interaction energies. Trends in the internal force constant and harmonic frequency values are discussed in terms of ion-molecular and ion-pair molecular interactions.

Magneto-structural correlation in (mu-alkoxo/hydroxo)(mu-carboxylato)dicopper(II) systems: Synthesis, X-ray structure and magnetic properties of aquo(mu-hydroxo) (mu-arylcarboxylato)bis(N,N,N ',N '-tetramethylethane-1,2-diamine)dicopper(II) diperchlorate

Asymmetrically dibridged dicopper(II) complexes, [Cu-2(OH)(O2CC6H4-p-Me)(tmen)(2)(H2O)](ClO4)(2) (1) and [Cu-2(OH)(O2CC6H4-p-OMe)(tmen)(2)(H2O)](ClO4)(2) (2) (tmen = N,N,N',N'-tetramethylethane-1,2-diamine), were prepared and structurally characterized. Complex 1 crystallizes in the monoclinic space group P2(1)/a with a = 17.718(2), b = 9.869(1), c = 19.677(2) Angstrom, beta = 115.16(1)degrees, V = 3114.3(6) Angstrom(3) and Z = 4. The structure was refined to R(wR(2)) = 0.067(0.178). Complex 2 crystallizes in the monoclinic space group P2(1)/a with a = 17.695(3), b = 9.574(4), c = 20.104(2) Angstrom, beta = 114.18(1)degrees, V = 3107(1) Angstrom(3) and Z = 4. The final residuals are R(wR(2)) = 0.067(0.182). The complexes have a [Cu-2(mu-OH)(mu-OH)(mu-O2CAr)](2+) core with tmen Ligands occupying the terminal sites of the core. In addition, one copper is axially bound to a water molecule. The Cu ... Cu distances and the Cu-OH Cu angles in the core are 3.394(1) Angstrom, 124.4(2)degrees for 1 and 3.374(1) Angstrom, 123.3(3)degrees for 2. The complexes show axial X-band EPR spectral features in methanol glass at 77 K giving g(perpendicular to) = 2.02, g(parallel to) = 2.3 (A(parallel to) = 165 x 10(-4) cm(-1)) and a visible band near similar to 630 nm in methanol. The complexes are weakly antiferromagnetic. A theoretical fit of the magnetic susceptibility data in the temperature range 40-295 K gives -J = 10 cm(-1), g = 2.05 for 1 and -J = 10 cm(-1), g = 2.0 for 2. Plots of -2J versus the Cu-OH-Cu angle (phi) in this class of asymmetrically dibridged dicopper(II) complexes having d(x2-y2)-d(x2-y2) magnetic orbitals show a linear magneto-structural correlation: -2J(cm(-1)) = 11.48 phi(deg) - 1373.