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Yadava, P.S.,A. Sarjubala Devi 한국생태학회 2004 Journal of Ecology and Environment Vol.27 No.4
The impact of slash and burning on microbial biomass C, N and P in soils of semi-evergreen tropical deciduous forest were studied from February 1999 to January 2000. The experimental sites were located near Moreh town in the Chandel district of Manipur state (India) along the Indo-Myanmar border between 23°49′ N ~ 24°28′N latitude and 93°45′E ~ 94°16′E longitude. Microbial biomass C ranged from 319.50 μg g-1 to 905.50 μg g-1 in the slash and burnt site and from 209.50 μg g-1 to 708.80 μg g-1 soil in the forest site. Microbial N ranged from 19.30 μg g-1 to 99.45 μg g-1 in the slash and burnt site and from 16.08 μg g-1 to 88.90 μg g-1 in the forest site. Microbial P varied from 10.90 μg g-1 to 32.21 μg g-1 in the slash and burnt site and from 2.50 μg g-1 to 17.60 μg g-1 in the forest site in different months throughout the year. Microbial biomass C, N and P were recorded to be higher in the slash and burnt site compared to the forest site .The conversion of forest into slash and burnt site for agriculture - the traditional shifting cultivation practiced by tribal people in the north- eastern India leads to addition of large amount of organic matter in the soil thereby exhibiting higher values of microbial biomass C, N and P in the recent slash and burnt site than that of the forest site. Relationship between the soil moisture, soil organic C and microbial biomass C, N and P were found to be correlated significantly in both the sites.
Viscosities of binary mixtures of ethanenitrile with benzene and several substituted benzenes
Sarvanand Singh Yadava,Shrinath Singh,Rati Bhan,Neetu Yadav 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.1
Viscosities (η) and densities (ρ) of five binary mixtures of ethanenitrile with benzene and several substituted benzenes viz methylbenzene, 1,4-dimethylbenzene, chlorobenzene and 1,2-dichlorobenzene have been experimentally determined at 308.15 K. Viscosity deviations (Δη) from the linear blending rule have been evaluated for all the mixtures studied. These are small with a maximum negative deviation of about 6% for binary mixture with benzene and maximum positive deviation of about 3% for mixture with 1,4-dimethylbenzene. Δη Values are fitted into Redlich -Kister equation and standard deviations in Δη values, σ (Δη) have been evaluated. The correlating performance of several viscosity models such as Grunberg - Nissan, Katti and Chaudhari, Hind-McLaughlin - Ubbelohde and Sedgwick has been evaluated. Grunberg-Nissan viscosity model is suitable for viscosities of several binary systems studied. The results are discussed in terms of molecular interactions between the components of binary mixtures.
Singh, L.,Yadava, S. S.,Sin, B. C.,Rai, U. S.,Mandal, K. D.,Lee, Y. Springer Science + Business Media 2016 Journal of electronic materials Vol.45 No.6
<P>The dielectric and ferroelectric characteristics of Bi0.5Na0.5TiO3 (BNT), CaCu3Ti4O12 (CCTO), and 0.5Bi(0.5)Na(0.5)TiO(3)-0.5CaCu(3)Ti(4)O(12) (BNT/CCTO) ceramics are compared. X-ray diffraction patterns confirmed the formation of single phase of all the ceramics after sintering at 950A degrees C for 15 h. Scanning electron microscopy images of the sintered ceramics reveal average grain sizes in the range from 200 nm to 2.5 mu m. Energy-dispersive x-ray mapping and x-ray photoelectron spectroscopy show the presence of the elements Bi, Na, Ca, Cu, Ti, and O with uniform distribution in the ceramics. BNT/CCTO exhibits high dielectric constant (epsilon (r) similar to 6.9 x 10(4)) compared with BNT (epsilon (r) similar to 0.13 x 10(4)) and CCTO (epsilon (r) similar to 1.68 x 10(4)) ceramics at 1 kHz and 503 K. The high dielectric constant of BNT/CCTO compared with BNT and CCTO is associated with a major contribution from grain boundaries, as confirmed by impedance and modulus analyses. The P-E hysteresis loop of all the ceramics measured at room temperature and 50A degrees C exhibited typical ferroelectric nature. The remanent polarization (P (r)) of BNT (1.58 mu C/cm(2)) and CCTO (0.654 mu C/cm(2)) ceramics are higher than that of BNT/CCTO (0.267 mu C/cm(2)) ceramic.</P>
Pallvita Yadav,Vinod Yadava,Audhesh Narayan 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1
Alumina epoxy nanocomposite (AENC) is an emerging class of composites with a wide range of functionality and applicability; however, managing AENC using a machine is difficult because of its special mixed characteristics. The presence of extremely hard alumina particles in soft epoxy matrix enhances material properties. The present work investigates the kerf characteristics of a straight cut made in AENC through Wire electrochemical spark cutting (WECSC) process. The kerf characteristics, such as kerf deviation and taper, are used to measure the cut quality. The applied voltage, electrolyte concentration, wire velocity, pulse on-time and pulse off-time are varied, and their effects on the kerf characteristics are experimentally investigated in a developed setup. Influencing parameters for straight cutting of AENC are applied voltage, concentration of electrolyte and wire velocity.
Gyanendra Kumar Singh,Vinod Yadava,Raghuvir Kumar 한국정밀공학회 2010 International Journal of Precision Engineering and Vol.11 No.4
Electro-discharge machining (EDM) characteristics of tungsten carbide-cobalt composite are accompanied by a number of problems such as the presence of resolidified layer, large tool wear rate and thermal cracks. Use of combination of conventional grinding and EDM (a new hybrid feature) has potential to overcome these problems. This article presents the face grinding of tungsten carbide-cobalt composite (WC-Co) with electrical spark discharge incorporated within face of wheel and flat surface of cylindrical workpiece. A face grinding setup for electro- discharge diamond grinding (EDDG) process is developed. The effect of input parameters such as wheel speed, current, pulse on-time and duty factor on output parameters such as material removal rate (MRR), wheel wear rate (WWR) and average surface roughness (ASR), are investigated. The present study shows that MRR increases with increase in current and wheel speed while it decreases with increase in pulse on-time for higher pulse on-time (above 100 μs). The most significant factor has been found as wheel speed affecting the robustness of electro- discharge diamond face grinding (EDDFG) process.
Experimental Study of Erosion and Abrasion based Hybrid Machining of Hybrid Metal Matrix Composite
Ravindra Nath Yadav,Vinod Yadava 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
Machining of metal matrix composites (MMCs) are still a challenge for manufacturing industries. Among various machining processes, electrical discharge machining (EDM) and diamond grinding (DG) are more acceptable processes for machining of the MMCs. In this paper, a new compound wheel (CW) is developed in such a way that both processes (EDM and DG) occur in alternate way due to the rotation of wheel. The performance of erosion and abrasion based hybrid machining (EAHM)process has been tested on hybrid aluminium-silicon carbide-graphite (Al/SiC/Gr) composite in terms of material removal rate (MRR) and average surface roughened (Ra). The experiments have been conducted on EDM machine with application of CW for effective spark erosion and abrasive abrasion machining. The effects of pulse current, pulse duration, pulse interval and wheel speed on MRR and Ra has been experimentally investigated and discussed.