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11.
MK Bhide RM Kadam MD Sastry Ajay Singh Shashwati Sen Manmeet Kaur DK Aswal SK Gupta VC Sahni 《Pramana》2002,58(5-6):799-802
Microwave absorption studies have been carried out on MgB2 superconductor using a standard X-band EPR spectrometer. The modulated low-field microwave absorption signals recorded for
polycrystalline (grain size ∼ 10 μm) samples suggested the absence of weak-link character. The field dependent direct microwave
absorption has been found to obey a ✓H dependence with two different slopes, which indicated a transition from strongly pinned lattice to flux flow regime. 相似文献
12.
Epitaxial La1−x
Pb
x
MnO3 (LPMO) thin films, grown on (100) SrTiO3 substrates by laser ablation technique at different temperatures between 600 and 850°C, have been characterized for electrical
and magnetic properties. The temperature dependence of resistivity showed that the metal-insulator transition temperature
(T
MI) decreases with increasing substrate temperature, which has been attributed to decrease in Pb content in the filsm. The YBa2Cu3O
x
/La1−x
MnO3 heterostructures, exhibiting both superconductivity and ferromagnetism, have been fabricated. 相似文献
13.
The dielectric relaxation phenomena of rigid polar liquid molecules chloral and ethyltrichloroacetate (j) in benzene, n-hexane and n-heptane (i) under 4.2, 9.8 and 24.6 GHz electric fields at 30°C are studied to show the possible existence of double relaxation times τ 2 and τ 1 for rotations of the whole and the flexible parts of molecules. The probability of showing double relaxation is more in aliphatic solvents indicating their nonrigidity. The symmetric and asymmetric distribution parameters γ and δ are obtained from X ij ′ /X 0ij and X ij ″ /X 0ij and w j →0 where X ij ′ and X ij ″ are real and imaginary parts of the complex orientational susceptibility X i * and X 0ij is the low frequency susceptibility which is real. X ij ’s are involved with the measured dielectric relative permittivities ε ij ′ , ε in ″ , ε 0ij and ε ∞ij of solutions. The theoretical weighted contributions c 1 and c 2 towards dielectric dispersions by Fröhlich’s method are compared with the experimental ones obtained from the graphical variation of X ij ′ /X 0ij and X ij ″ /X 0ij with weight fractions w j ’s at w j → 0. The measured dipole moments μ 2 and μ 1 of the whole and the flexible part of a polar molecule in terms of the linear coefficients β’s of X ij ′ ’s with w j ’s and the estimated τ 2 and τ 1 reveal their associations with aliphatic solvents. The theoretical dipole moments μ theo’s from the available bond angles and bond moments of the substituent polar groups of the molecules with the estimated μ’s suggest the mesomeric, inductive and electromeric effects in them under GHz electric field. 相似文献
14.
15.
S Chopra N S Pawar M P Singh Rakesh Kumar J Prasad V P Patel Raj Pal B Kumar S Ojha K Devarani T Nandi M Sota P Barua S Gargari R Joshi D Kanjilal SK Datta 《Pramana》2002,59(5):753-759
The 15 UD pelletron at NSC has been operational and performed well during the last 11 years. There have been major modifications
performed for upgradation of pelletron system over this period. Major upgradations which have been implemented are new resistor
network system for voltage gradient, doublet to singlet unit conversion for accelerator units, turbopump based gas stripper
system etc. In addition accelerator mass spectroscopy program has also been started. A new multi-cathode source, Wien filter
etc. have been procured and will be added soon in the system. An overview of the most significant upgradations undertaken
and other activities for the system are being reported in the present paper. 相似文献
16.
Provably secure dynamic identity-based three-factor password authentication scheme using extended chaotic maps 总被引:1,自引:0,他引:1
SK Hafizul Islam 《Nonlinear dynamics》2014,78(3):2261-2276
With the aim of guaranteeing secure communication through public networks, three-factor password authentication (TF-PWA) scheme plays a key role in many internet applications. Since in TF-PWA scheme, the communicating entities can mutually authenticate each other and generate a shared session key, which will be used for secure exchange of messages in succeeding communication among them. As a result, the TF-PWA schemes gain enormous consideration in recent years. More recently, due to light-weight features of the extended chaotic map, it is also extensively applied in designing of public key encryption, key agreement, image encryption, S-box, hash function, digital signature, password authentication, etc. The aim of this paper was to design a dynamic identity-based three-factor password authentication scheme using extended chaotic map (ECM-TF-PWA) in the random oracle model. The proposed scheme is provably secure based on the intractability assumption of chaotic map-based Diffie–Hellman problem. The informal security analysis gives the evidence that our scheme protects all attacks and provides functionality attributes that are needed in a three-factor authentication system. Besides, the performance discussion shows that our scheme performs better than others in respect of computation and communication cost. 相似文献
17.
SK. Musharaf Ali 《Molecular physics》2013,111(4):387-393
We propose a simple hybrid model for the shear viscosity of isotopic fluid mixtures by coupling the contribution of the Stokes–Einstein relation with the existing linear model of Roults's law for the shear viscosity. The calculated values of shear viscosity using this simple hybrid model are found to be in excellent agreement with the molecular dynamics (MD) simulation results. The calculated value of the shear viscosity obtained from the theoretical model as well as the MD simulation increases with increasing mass ratio. 相似文献
18.
The effect of Nd3+ concentration on the CW and Q-switched laser performances at 1064 nm from Nd: YVO4 has been studied under diode laser pumping in identical laser configuration. The Nd3+ concentrations used were 1, 2 and 3 at.% in YVO4 crystals. Under the CW operations we have compared the thermal lensing effect, slope efficiencies and also the beam quality
at the fourth-order degeneracy configuration. Q-switching was done with the help of an acousto-optic modulator and we have
compared the pulses obtained from Nd: YVO4 laser with different doping concentration. It was found that the 1 at.%-doped crystal is the best, offering highest optical-to-optical
conversion efficiency (55%), lowest fractional heat load (24%), highest pulse energy (80 μJ) and shortest pulse width (20 ns). It was also found that there was not much difference in performances for 2 and 3 at.%-doped
crystals both in CW and Q-switched configurations. 相似文献
19.
SHA. Hashemi Kachapi Rao V. Dukkipati S.Gh. Hashemi K. S.Mey. Hashemi K. S.Meh. Hashemi K. SK. Hashemi K. 《Nonlinear Analysis: Real World Applications》2010,11(3):1431-1441
An analytical approach is developed for areas of nonlinear science such as the nonlinear free vibration of a conservative, two-degree-of-freedom mass–spring system having linear and nonlinear stiffnesses. The main contribution of this research is twofold. First, it introduces the transformation of two nonlinear differential equations for a two-mass system using suitable intermediate variables into a single nonlinear differential equation and, more significantly, the treatment of a nonlinear differential system by linearization coupled with Newton’s method. Secondly, the major section is the solving of the governing nonlinear differential equation where the displacement of the two-mass system can be obtained directly from the linear second-order differential equation using a first-order variational approach. The aforementioned approach proposed by J.H. He, who actually developed the method, is exactly He’s variational method. This approach is an explicit method with high validity for resolving strong nonlinear oscillation system problems. Two examples of nonlinear two-degree-of-freedom mass–spring systems are analyzed, and verified with published results and exact solutions. The method can be easily extended to other nonlinear oscillations and so could be widely applicable in engineering and science. 相似文献
20.
Sungwon Choi Andrew P. Janisse Changhua Liu Elliot P. Douglas 《Journal of polymer science. Part A, Polymer chemistry》2011,49(21):4650-4659
In this study, the effect of water addition on cure kinetics in an epoxy‐amine thermoset was investigated. Near FTIR spectra demonstrated that a small amount of water addition significantly accelerated the cure reaction in terms of epoxide conversion, with water acting as a catalyst for the reaction. Use of a modified mechanistic model allowed direct comparison of the effect of hydroxyl groups generated from water addition to those generated from the polymer chain. The comparison of those kinetic parameters shows that the two effects are very close, in which difference in the logarithmic value of the reaction constant is less than one order of magnitude over all the reaction conditions. The kinetic study also confirmed a strong negative substitution effect for this system. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献