248 research outputs found
Brownian dynamics simulations of planar mixed flows of polymer solutions at finite concentrations
Periodic boundary conditions for planar mixed flows are implemented in the
context of a multi-chain Brownian dynamics simulation algorithm. The effect of
shear rate , and extension rate , on the size of
polymer chains, \left, and on the polymer contribution to
viscosity, , is examined for solutions of FENE dumbbells at finite
concentrations, with excluded volume interactions between the beads taken into
account. The influence of the mixedness parameter, , and flow strength,
, on \left and , is also examined, where
corresponds to pure shear flow, and
corresponds to pure extensional flow. It is shown that there exists a critical
value, , such that the flow is shear dominated for , and extension dominated for .Comment: 18 pages, 12 figures, to appear in Chemical Engineering Scienc
Performance Evaluation of \u3cem\u3eKharif\u3c/em\u3e and \u3cem\u3eRabi\u3c/em\u3e Fodder Sorghum in Namsai District of Arunachal Pradesh
Deficiency of feed and fodder accounts for half of the total loss in dairy farming therefore, forages are called as backbone of livestock industry. The scarcity of green forages and grazing resources in the country has made the livestock to suffer continuously with malnutrition resulting in their production potentiality at sub-optimum level as compared to many developed nations (Anonymous, 2012). Arunachal Pradesh is well known for its ever green vegetation and biodiversity under hilly ecosystem. Though, it is situated at remotest part of country but possess huge scope of livestock farming. Namsai district of Arunachal Pradesh is a bordering district of Assam and having huge potential of milk production and its marketing which may help to improve the economic condition and poverty eradication of rural people. Cow is a major dairy animal here, however, the milk production capacity is very low as compared to other parts of the country. Dairy cow are reared in century old traditional way therefore, there are several areas of dairy management which needs improvement. Scarcity of feed and fodder is one of the major bottleneck which needs to be addressed urgently. Namsai district has very limited number of fodder crop and farmers mainly depend on non-conventional, public grazing land and forest vegetation. KVK Lohit (Namsai district) has introduced fodder sorghum in rainy and winter season for the first time in the district purposefully to improve the fodder availability under organized dairy farming in Namsai district
The Synthesis and Characterization of LiFeAs and NaFeAs
The newest homologous series of superconducting As-pnictides, LiFeAs (Li111)
and NaFeAs (Na111) have been synthesized and investigated. Both crystallize
with the layered tetragonal anti-PbFCl-type structure in P4/nmm space group.
Polycrystalline samples and single-crystals of Li111 and Na111 display
superconducting transitions at ~ 18 K and 12-25 K, respectively. No magnetic
order has been found in either compound, although a weak magnetic background is
clearly in evidence. The origin of the carriers and the stoichiometric
compositions of Li111 and Na111 were explored.Comment: submitted for publication in Physica C special issue on Fe-pnictide
Real Time Power System and Sub Synchronous Inter Harmonics
Real time Power system is associated with different types of abnormalities which percolate into the system thus generating various spurious signals, which ultimately results in massive breakdown of the same. In this scope of work, we have intended to design a real time power system using MATLAB (Version7.8.0.347) (R2009a) and incorporating Continuous Wavelet Transform and also we have developed a program for effective identification of sub-harmonics, generated or carried into the system due to the power system behavioral nature
The Unusual Superconducting State at 49 K in Electron-Doped CaFe2As2 at Ambient
We report the detection of unusual superconductivity up to 49 K in single
crystalline CaFe2As2 via electron-doping by partial replacement of Ca by
rare-earth. The superconducting transition observed suggests the possible
existence of two phases: one starting at ~ 49 K, which has a low critical field
~ 4 Oe, and the other at ~ 21 K, with a much higher critical field > 5 T. Our
observations are in strong contrast to previous reports of doping or
pressurizing layered compounds AeFe2As2 (or Ae122), where Ae = Ca, Sr or Ba. In
Ae122, hole-doping has been previously observed to generate superconductivity
with a transition temperature (Tc) only up to 38 K and pressurization has been
reported to produce superconductivity with a Tc up to 30 K. The unusual 49 K
phase detected will be discussed.Comment: 11 pages, 8 figure
Evidence for multiple gaps in specific heat of LiFeAs crystals
The zero-field specific heat of LiFeAs was measured on several single
crystals selected from a bulk sample. A sharp Delta Cp/Tc anomaly of
approximately 20 mJ/(mole x K^2) was observed. The value appears to be between
those of SmFeAs(O0.9F0.1) and (Ba0.6K0.4)Fe2As2, but bears no clear correlation
with their Sommerfeld coefficients. The electronic specific heat below Tc
further reveals a two-gap structure with the narrower one only on the order of
0.7 meV. While the results are in rough agreement with the Hc1(T) previously
reported on both LiFeAs and (Ba0.6K0.4)Fe2As2, they are different from the
published specific-heat data of a (Ba0.6K0.4)Fe2As2 single crystal.Comment: 19 pages, 5 figure
Lower Critical Field, Anisotropy, and Two-Gap Features of LiFeAs
The magnetic properties of LiFeAs, as single crystalline and polycrystalline
samples, were investigated. The lower critical field deduced from the vortex
penetration of two single crystals appears to be almost isotropic with a
temperature dependence closer to that of two-gap superconductors. The
parameters extracted from the reversible magnetizations of sintered
polycrystalline samples are in good agreement with those from the single
crystal data.Comment: 19 pages, 5 figure
Structural study on hole-doped superconductors Pr1-xSrxFeAsO
The structural details in Pr1-xSrxFeAsO (1111) superconducting system are
analyzed using data obtained from synchrotron X-ray diffraction and the
structural parameters are carefully studied as the system is moving from
non-superconducting to hole-doped superconducting with the Sr concentration.
Superconductivity emerges when the Sr doping amount reaches 0.221. The linear
increase of the lattice constants proves that Sr is successfully introduced
into the system and its concentration can accurately be determined by the
electron density analyses. The evolution of structural parameters with Sr
concentration in Pr1-xSrxFeAsO and their comparison to other similar structural
parameters of the related Fe-based superconductors suggest that the interlayer
space between the conducting As-Fe-As layer and the insulating Pr-O-Pr layer is
important for improving Tc in the hole-doped (1111) superconductors, which
seems to be different from electron-doped systems.Comment: 17 pages, 7 figures, 1 tabl
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