Electrochemical incineration of wastes

The novel technology of waste removal in space vehicles by electrochemical methods is presented to convert wastes into chemicals that can be eventually recycled. The important consideration for waste oxidation is to select a right kind of electrode (anode) material that should be stable under anodic conditions and also a poor electrocatalyst for oxygen and chlorine evolution. On the basis of long term electrolysis experiments on seven different electrodes and on the basis of total organic carbon reduced, two best electrodes were identified. The effect of redox ions on the electrolyte was studied. Though most of the experiments were done in mixtures of urine and waste, the experiments with redox couples involved 2.5 M sulfuric acid in order to avoid the precipitation of redox ions by urea. Two methods for long term electrolysis of waste were investigated: (1) the oxidation on Pt and lead dioxide electrodes using the galvanostatic methods; and (2) potentiostatic method on other electrodes. The advantage of the first method is the faster rate of oxidation. The chlorine evolution in the second method is ten times less then in the first. The accomplished research has shown that urine/feces mixtures can be oxidized to carbon dioxide and water, but current densities are low and must be improved. The perovskite and Ti4O7 coated with RuO2 are the best electrode materials found. Recent experiment with the redox agent improves the current density, however, sulphuric acid is required to keep the redox agent in solution to enhance oxidation effectively. It is desirable to reduce the use of acid and/or find substitutes

Electric power demand forecasting: A case study of Lucknow city

The study of forecasting identifies the urgent need for special attention in evolving effective energy policies to alleviate an energy famine in the near future. Since power demand is increasing day by day in entire world and it is also one of the fundamental infrastructure input for the development, its prospects and availability sets significant constraints on the socio-economic growth of every person as well as every country. A care full long-term power plan is imperative for the development of power sector. This need assumes more importance in the state of Uttar Pradesh where the demand for electrical energy is growing at a rapid pace. This study analyses the requirement of electricity with respect to the future population for the major forms of energy in the Lucknow city in Uttar Pradesh state of India. A model consisting of significant key energy indicators have been used for the estimation. Model wherever required refined in the second stage to remove the effect of auto-correlation. The accuracy of the model has been checked using standard statistical techniques and validated against the past data by testing for 'expost' forecast accuracy

Modulated structure in the martensite phase of Ni1.8Pt0.2MnGa: a neutron diffraction study

7M orthorhombic modulated structure in the martensite phase of Ni1.8Pt0.2MnGa is reported by powder neutron diffraction study, which indicates that it is likely to exhibit magnetic field induced strain. The change in the unit cell volume is less than 0.5% between the austenite and martensite phases, as expected for a volume conserving martensite transformation. The magnetic structure analysis shows that the magnetic moment in the martensite phase is higher compared to Ni2MnGa, which is in good agreement with magnetization measurement

Control of bow shock induced three-dimensional separation using bleed through holes

The unsteady three-dimensional separated flow on a wall induced by a square protrusion (approximately twice the local boundary layer thickness in width and height), and its control by means of passive suction through holes, is investigated using wind tunnel experiments at Mach $2.87$. The baseline flow without any control was characterized and compared against the cases with bleed. A bow-shaped separation line on the wall with a mid-span separation length of $5.57\delta$ from protrusion face was traced from oil-flow visualization. The averaged pressure distribution surveyed using static pressure ports placed on the wall has mapped plateau, high-pressure, and a low-pressure region in the separated flow, distinctive to three-dimensional interactions. Ten control configurations were tested with suction holes placed along mid-span in the different pressure zones. Significant spanwise `Mean Reduction in Separation Length' of up to $0.93\delta$ was observed from oil-flow visualization. A comparison of observations from various control configurations suggested that bleeding the flow from the high-pressure region could in general delay the separation and reduce the bubble size. Further, time-resolved schlieren visualizations have confirmed reduction in both `mid-span separation length' and `shock-intermittent-region' with the introduction of suction in high-pressure region. Fourier and Proper Orthogonal Decomposition analysis done on the schlieren data has confirmed the presence of low-frequency separation-shock oscillations at Strouhal Numbers of order $10^{-2}$, both with and without control. Furthermore, the amplitudes of separation-shock oscillations in the spectrum were reduced with the introduction of suction simultaneously from two holes placed in high and low-pressure regions

Spatial distribution of Brevicoryne brassicae (L.) in Cabbage in mid-hills of Himachal Pradesh, India

Investigations were carried out during two consecutive Rabi seasons of 2014 and2015 at the Experi-mental Farm of the Department of Seed Science and Technology, Dr Y S Parmar University of Horticulture and For-estry, Nauni, Solan, Himachal Pradesh, India to study the spatial distribution of Brevicoryne brassicae in cabbage. One month old cabbage seedlings were planted in the field in the month of November during both the years. Distri-bution pattern of any insect population is an important aspect as it represents the interaction between individuals of the species and their habitat. Spatial distribution is useful for designing efficient sampling programmes for population estimation and development of population models. Spatial distribution is also important to understand the bioecology of the pest and to determine the sampling protocol for that species. In the present study variance to mean ratio (s2/X),mean crowding (X*), ratio of mean crowding to mean (X*/X), ‘k’ of negative binomial, Taylor’s power equation(s2 = 0.9099X1.55 during 2014 and s2 = 2.9861X1.1949 during 2015), Iwao’s patchiness regression and optimum number of samples (Nopt) required to achieve the desired precision were calculated for different densities. Cabbage aphid, B. brassicae appeared in the fourth standard week i.e last week of January( 26.2 aphids/ plant during 2014 and 0.30 aphids/ plant during 2015) and persisted upto thirteenth standard week i.e last week of April ( 18.4 aphids/ plant during 2014 and 18.2 aphids/ plant during 2015) and followed a negative binomial distribution during both years. Optimum number of samples (Nopt) required varied with mean density as well as precision level. The present study will serve as basic information to develop a sampling plan of B. Brassicae in cabbage for its monitoring and management

Graphene boosts thermoelectric performance of a Zintl phase compound

The concept of nanocomposites derived by incorporating a second minor phase in bulk thermoelectric materials has established itself as an effective paradigm for optimizing high thermoelectric performance. In this work, this paradigm is for the first time extended to bulk Zintl phase Mg3Sb2 and its isoelectronically Bi-doped derivative Mg3Sb1.8Bi0.2 system. Herein, we report the synthesis, microstructural details, electronic structure and thermoelectric properties of (Mg3Sb2, Mg3Sb1.8Bi0.2)/ graphene nanosheet (GNS) nanocomposites with different mass ratios. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) investigation reveals that Mg3Sb2 nanoparticles are homogenously anchored on the surface of GNS. We demonstrate that Mg3Sb2-based materials incorporated with a small content of graphene outperform optimally, resulting in potential p-type thermoelectric materials. The present nanocomposite additive of GNS deriving such a novel nanocomposite of (Mg3Sb2, Mg3Sb1.8Bi0.2)/GNS, enhances the electrical conductivity significantly, thereby resulting in a substantially large increase in the power factor. The enhanced electrical conductivity of these nanocomposites is attributed to the increase in the carrier concentration and high carrier mobility owing to the ultra high mobility of graphene. X-ray photoelectron spectroscopy (XPS) core level spectra confirm weak bonding between GNS and Mg3Sb2. Increase in carrier concentration is reflected in XPS valence band spectra and change in spectral weight near valence band maxima is indicative of increased electrical conductivity in the nanocomposite material. The thermal conductivity of these nanocomposites is noted to be reduced at high temperature. These favorable conditions lead to enhanced thermoelectric figure-of-merit (ZT) = 0.71 at 773 K for Mg3Sb2/GNS and a ZT = 1.35 at 773 K for Mg3Sb1.8Bi0.2/GNS nanocomposites with the mass ratio of 80 : 1 which are similar to 170% and similar to 125% higher values compared to bare Mg3Sb2 and bare Mg3Sb1.8Bi0.2 respectively. We strongly believe that the present novel strategy of fabricating such a nanocomposite of a Zintl compound by utilizing GNS as a nanocomposite additive, may provide an emerging path for improving thermoelectric properties of various Zintl phase compounds

Study of Unsteadiness due to 3-D Shock-Boundary Layer Interaction in Flow over a Square-faced Protuberance

The dynamics of shock-induced unsteady separated flow past a three-dimensional square-faced protuberance is investigated through wind tunnel experiments. Time-resolved schlieren imaging and unsteady surface pressure measurements are the diagnostics employed. Dynamic Mode Decomposition (DMD) of schlieren snapshots, and analysis of spectrum and correlations in pressure data are used to characterize and resolve the flow physics. The mean shock foot in the centreline is found to exhibit a Strouhal number of around 0.01, which is also the order of magnitude of the Strouhal numbers reported in the literature for two-dimensional shock-boundary layer interactions. The wall pressure spectra, in general, shift towards lower frequencies as we move away from (spanwise) centreline with some variation in the nature of peaks. The cross-correlation analysis depicts the strong dependence of the mean shock oscillations to the plateau region, and disturbances are found to travel upstream from inside the separation bubble. Good coherence is observed between the spanwise mean shock foot locations till a strouhal number of about 0.015 indicating that the 3-D shock foot largely moves to-and-fro in a coherent fashion.Comment: 16 pages, 21 figure

Structural and Electronic Properties of HfN: ab initio calculation

The structural and electronic properties of HfN from an electronic structure calculation have been presented.  The calculation is performed using self-consistent tight binding linear muffin tin orbital (TB-LMTO) method within the local density approximation (LDA).     The calculated equilibrium structural parameters are in good agreement with the available experimental results.  It is found that this compound shows metallic behavior under ambient condition.  The electronic structures of HfN in B1 phase are investigated.  It is found that HfN have strong metallization and the hybridizations of atoms in B1 phase. Keywords: Bulk modulus, band structure, density of states