Studies on Preparation, Characterization and Ammoxidation Functionality of Zirconium Phosphate-Supported V2O5 Catalysts

Zirconium pyrophosphate (ZrP₂O₇) was synthesized from zirconyl chloride and phosphoric acid. A series of ZrP₂O₇-supported V₂O₅ catalysts, with the oxide loading ranging from 2 to 8 wt.%, was prepared by wet impregnation method. These catalysts were characterized by various techniques like X-ray diffraction, BET surface area, pore size distribution, FT-IR spectroscopy, acidity measurements and X-ray photoelectron spectroscopy. Their catalytic functionality was evaluated in the ammoxidation of 2-methyl pyrazine (MP) to 2-cyano pyrazine (CP). The V₂O₅/ZrP₂O₇ catalysts are found to be highly active and selective. FT-IR profiles of used catalysts indicate the interaction of ammonia with vanadia. The physico-chemical properties of the catalysts are correlated with their activity and nitrile selectivity. IICT Communication No. 050602.     

Effect of P/Fe ratio on the structure and ammoxidation functionality of Fe-P-O catalysts

Bulk FePO₄ catalysts, with varying P/Fe atomic ratio in the range of 1–1.6, were prepared and characterized by XRD, FT-IR, TPR, Potentiometric titration, Laser Raman, TEM, XPS and TG/DTA techniques in order to study the influence of P/Fe atomic ratio on the nature and extent of the active phase formation. The data obtained from XRD and Laser Raman techniques suggested predominant formation of the quartz type iron phosphate at close to stoichiometric P/Fe ratio, but as the ratio increased beyond 1.4 a progressive transformation of monomeric phosphate into its polymeric form was observed. XPS spectra reflected the presence of iron in its 3+ state when P/Fe ≤ 1.2 and exists as Fe²⁺ and Fe³⁺ when P/Fe ≥ 1.4. The catalytic properties of these iron phosphates were studied in the vapor phase ammoxidation, taking 2-methylpyrazine (MP) to 2-cyanopyrazine (CP) as an example. The ammoxidation activity of the catalysts was found to be proportional to the extent of quartz phase formed which in turn was proportional to the redox property, as observed by the oxidation functionality of the catalysts in benzyl alcohol transformation. However, the selectivity to nitrile was found to be dependent on the acid strength of the catalysts.     

A polypyrrole based gas sensor for detection of volatile organic compounds (VOCs) produced from a wheat bread

Early detection of contamination in food items is the current interest of research. Changes in concentration of volatile organic compounds emitted by the food items can provide valuable information about its contamination. Hence, a polypyrrole based gas sensor is developed for the detection and monitoring the organic volatiles produced from wheat bread during storage. Gas chromatography?Cmass spectroscopy results show that 1-heptanol, 1-pentanol, 1-octanol are the predominant volatiles produced from wheat bread during storage. Multifrequency impedance measurement technique is used to monitor the changes in electrical properties, mainly capacitance of the developed sensor over a frequency range 10 Hz?C2 MHz upon exposure to the above organic volatiles produced from the bread during storage of 120 h. Electrical property data show that the quantitative change in the above volatiles has influence on the change in capacitance of the developed sensor.     

GaAs/Ge and silicon solar cell capacitance measurement using triangular wave method

The capacitance of GaAs/Ge and silicon (BSFR) solar cells are measured at different temperature ranging from 288 to 338 K under dark condition using triangular wave method. It is a frequency domain technique. In the proposed method, the solar cells are biased externally using DC voltage at the desired operating voltage and the AC triangle wave small signal of desired amplitude with variable frequencies are applied. The resultant AC current of the device is measured and the cell capacitance is calculated. GaAs/Ge solar cell has shown only transition capacitance throughout its operating voltage while silicon (BSFR) solar cell exhibited both transition and diffusion capacitances. It is a direct and simple measurement technique in comparison to impedance spectroscopy and other bridge methods.     

Entropy Generation Analysis of the MHD Flow of Couple Stress Fluid between Two Concentric Rotating Cylinders with Porous Lining

An attempt has been made to study the entropy generation analysis of couple stress fluid flow in an annulus between two concentric rotating vertical cylinders. There is a porous lining attached to the inside of an outer cylinder. The flow is under the influence of a radial magnetic field. The flow in the annular gap is caused by rotation of the cylinders. The Stokes couple stress flow model is employed. The flow in the porous sleeve is governed by Darcy's law. The velocity, temperature, entropy generation number, Bejan number, wall shear stress and heat transfer rate at the inner and outer cylinders are obtained numerically by employing a finite difference scheme with vanishing of couple stresses on the boundary. The effect of relevant parameters on the flow and entropy generation rate are discussed and depicted through graphs.     

PC-Based Management Game for Irrigated Farming

Abstract: Irrigated farming is a complex activity influenced by a large number of interacting and random factors. A sufficiently realistic gaming simulation model can be used as an effective tool for training in decision making under such a setting. This paper describes a microcomputer-based game model CASIMBOL (Computer Aided Simulation of Irrigation Management Below OutLet) that deals with the problems faced by a typical farmer in a water-deficient region in southern India. The model is built in a spreadsheet environment. Menu-driven macros are developed for automating the gaming session, with provision for selective revision of random variable values. A case-specific synthetic knowledge base is made available for consultation at selected stages during the progress of the game. The advantages, limitations and further possibilities of this model have been brought out during trial sessions involving academic and field personnel. The spreadsheet-based game model linked to a mini expert system demonstrates that this methodology can be adopted for similar situations.     

A simple control technique for single-SEPIC converter based multiple output SMPS with fully regulated and isolated outputs

Switched mode power supplies (SMPS) with multiple outputs are commonly used for powering up personal computers and many other consumer electronic appliances. Multiple output SMPS circuits normally employ several DC/DC converters for regulating the voltage in each of the outputs. In this paper, a single single ended primary inductance converter (SEPIC) is used to obtain multiple isolated and regulated DC outputs from a single unregulated DC input, so that the reliability and cost effectiveness of the system can be enhanced. Considering that a large number of SMPS are being used in various applications, it is essential to maintain good power quality at the AC mains side of the SMPS circuit adhering to the international standards. Average current control mode has been used in this paper to achieve unity power factor and sinusoidal current at the input side. A novel weighted error approach has been proposed to achieve excellent voltage regulation at all the outputs of the SMPS irrespective of the load variations and input supply fluctuations. The proposed system has been designed and simulated in a PSIM environment and implemented in hardware. The results obtained show an enhanced performance of the power supply in terms of its output voltage regulation and input power quality.     

Resistivity imaging of a reconfigurable phantom with circular inhomogeneities in 2D-electrical impedance tomography

Resistivity imaging of a reconfigurable phantom with circular inhomogeneities is studied with a simple instrumentation and data acquisition system for Electrical Impedance Tomography. The reconfigurable phantom is developed with stainless steel electrodes and a sinusoidal current of constant amplitude is injected to the phantom boundary using opposite current injection protocol. Nylon and polypropylene cylinders with different cross sectional areas are kept inside the phantom and the boundary potential data are collected. The instrumentation and the data acquisition system with a DIP switch-based multiplexer board are used to inject a constant current of desired amplitude and frequency. Voltage data for the first eight current patterns (128 voltage data) are found to be sufficient to reconstruct the inhomogeneities and hence the acquisition time is reduced. Resistivity images are reconstructed from the boundary data for different inhomogeneity positions using EIDORS-2D. The results show that the shape and resistivity of the inhomogeneity as well as the background resistivity are successfully reconstructed from the potential data for single or double inhomogeneity phantoms. The resistivity images obtained from the single and double inhomogeneity phantom clearly indicate the inhomogeneity as the high resistive material. Contrast to noise ratio (CNR) and contrast recovery (CR) of the reconstructed images are found high for the inhomogeneities near all the electrodes arbitrarily chosen for the entire study.     

Studies on glass transition and starch re-crystallization in wheat bread during staling using electrical impedance spectroscopy

Bread staling is a very complex phenomenon that is not yet completely understood. The present work explains how the electrical impedance spectroscopy technique can be utilized to investigate the effect of staling on the physicochemical properties of wheat bread during storage. An instrument based on electrical impedance spectroscopy technique is developed to study the electrical properties of wheat bread both at its crumb and crust with the help of designed multi-channel ring electrodes. Electrical impedance behavior, mainly capacitance and resistance, of wheat bread at crust and crumb during storage (up to 120 h) is investigated. The variation in capacitance showed the glass transition phenomenon at room temperature in bread crust after 96 h of storage with 18% of moisture in it. The resistance changes at bread crumb showed the starch recrystallization during staling.Industrial relevanceSimultaneous measurement of moisture content, glass transition and starch recrystallization is possible with the designed instrument without disturbing the experimental set-up. Thus, the present work is going to help manufacturers and researchers to understand the bread staling phenomenon at crust and crumb without opting very complex instrumental procedures.     

Assessment of groundwater quality and its suitability for agricultural usage in and around Rangampeta area,Andhra Pradesh,south India

The aim of this study is to assess the groundwater quality of Rangampeta area for irrigation and domestic purposes. The groundwater samples were analyzed for distribution of chemical elements Ca, Mg, Na, K, Si, HCO₃, CO₃, Cl and SO₄. It also includes pH, electrical conductivity, total hardness, non carbonate hardness and total alkalinity. The parameters like sodium absorption ratio, adjusted sodium absorption ratio, sodium percentage, potential salinity, permeability index and residual sodium carbonate were calculated. The dominant hydrochemical facies of groundwater are Ca–Mg–Cl and Na–Cl Water Types. The Gibbs’s diagram plots suggest that the chemical weathering of rock forming minerals is the major driving force controlling water chemistry in this area. The positive chloro-alkaline indices revealed that the groundwater has suffered ion exchange between Na and K of water with Ca and Mg of soil during its flow.