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101.
This paper presents the influence of magnetic field on heat due to viscous and electrical dissipations for an incompressible, viscous, electrically conducting fluid through a circular pipe in the presence of an applied (transverse) uniform magnetic field. The walls of the pipe are assumed to be non-conducting and kept at uniform temperature gradient in one case and at a constant temperature gradient in another case. The heat equation governing the present problem is solved exactly in hypergeometric series. The temperature at the centre of the pipe Te, unweighted mean temperature Tm and weight mean temperature TM are calculated. The temperature profiles are shown graphically for different values of Hartmann number M, Brinkman number Br and a non-dimensional number S. Numerical calculations are made for the Nusselt number and are entered in the table. 相似文献
102.
Non-isothermal studies of the dehydration of double salt hydrates of the type K2AB4·M(II)SO4·6H2O where AB4BeF2?4 or SeO2?4 and M(II)Mg(II), Co(II), Ni(II), Cu(II) or Zn(II) and their D2O analogues were carried out. Thermal parameters like activation energy, order of reaction, enthalpy change, etc., for each step of dehydration were evaluated from the analysis of TG, DTA and DTG curves. These parameters were compared with the corresponding double sulphate, i.e., K2SO4·M(II)SO4·6H2O and their D2O analogues. The role of divalent cation on the thermal properties of dehydration of the salt hydrates and also the effect on the thermal properties due to deuteration were discussed. The order of reaction was always found unity. The values of ΔH were within ~11-~19 kcal mol?1 相似文献
103.
Condensation of bis(2-furanthiocarboxyhydradatometal(II), M(fth)2; [M (II) = Mn, Fe, Co, Ni, Cu and Zn] with pyridine-2- and -4-carboxaldehydes gave complexes of the formula M(pfth)2 [pfth? = pyridine-2-carboxaldehyde-2-furanthiocarboxyhydrazonato], Ni(Ifth)2, Zn(Ifth)2, Cu(Ifth) and Co(Ifth)3, (Ifth? = pyridine-4-carboxaldehyde-2-furanthiocarboxyhydrazonato). The magnetic and electronic spectral studies coupled with photoacoustic or Mössbauer spectra suggested octahedral geometry for the M(II) complexes with low-spin states for Co(Ifth)3 and Fe(pfth)2. IR and 1H NMR spectral studies of diamagnetic complexes suggested bonding through “azomethine” nitrogen and “thiolo” sulphur. IR spectra also showed the involvement of pyridine ring nitrogen in coordination in all the complexes except Cu(Itfh), Co(Ifth)3, and Zn(Ifth)2. Some of the compounds possessed antimicrobial activity. 相似文献
104.
105.
Radio pulses from extensive air showers (EAS) at 30, 44, and 60 MHz frequencies have been studied, using wide band broad-side
arrays of half-wave dipole antenna systems. The experimental results support the theoretical prediction that the field strength
of radio emission depends on the shower size. An asymmetry has been noticed in the pulse height distributions of radio pulses
detected by North-South and East-West directed arrays. These observations are in agreement with the theory that the charge
separation mechanism is predominant in generating radio pulses from EAS and radio emission is polarised in the East-West direction.
Experimental data are compared with those of earlier workers. 相似文献
106.
107.
The structure of129Ba is investigated through the beta decay of129La, whose half-life is measured to be 11.6±0.2 m. The decay properties are studied by means of beta, gamma and conversion electron spectroscopy techniques. Many transitions are observed and a level scheme of129Ba with deduced129Ba values is proposed. The total decay energy of129Ba is measured to be 3.72±0.05 MeV, which is compared with predictions of mass formulae. Low-lying structure of129Ba is discussed in terms of collective models. 相似文献
108.
Claudia Mattheis Martin C. Schwarzer Gernot Frenking Seema Agarwal 《Macromolecular rapid communications》2011,32(13):994-999
The first example of phantom ring‐closing condensation polymerization for the synthesis of oligoguanidines is presented. A new oligoguanidine with a ring structure was achieved in one step by the condensation reaction of a triamine, like diethylenetriamine, with guanidine hydrochloride. The condensation reaction proceeded by selective ring‐closure towards the formation of five‐membered rings in the oligomer backbone. The resulting polymer repeat unit structure was different from the starting monomers (phantom polymer) and was formed by elimination of three molecules of ammonia per repeat unit. The inter‐, intra‐, and inter‐molecular reaction sequences led to the new structure as proved by different spectroscopic techniques (atmospheric pressure chemical‐ionization mass spectrometry, and one‐dimensional and two‐dimensional homo‐ and heteronuclear correlation NMR experiments) as well as supported by quantum chemical investigations. Preliminary results regarding antibacterial use of the resulting oligoguanidine were also promising and showed its effect within 15–30 min as an antibacterial material.
109.
Charged analogue of Whittaker’s interior solution is derived which possess constant gravitational mass density (ρ+3p). The solution joins smoothly to Nordstörm solution at the pressure free interface. The solution has increasing energy density away from the center which is unphysical however such model can very well represent the situations when density undergoes abrupt changes during the tug of war between the gravitational attraction and electrostatic repulsion. 相似文献
110.
Chitra Shukla Anindita Banerjee Anirban Pathak 《International Journal of Theoretical Physics》2013,52(6):1914-1924
Recently, Hwang et al. (Eur. Phys. J. D 61:785, 2011) and Yuan et al. (Int. J. Theor. Phys. 50:2403, 2011) have proposed two efficient protocols of secure quantum communication using 3-qubit and 4-qubit symmetric W state respectively. These two dense coding based protocols are generalized and their efficiencies are considerably improved. Simple bounds on the qubit efficiency of deterministic secure quantum communication (DSQC) and quantum secure direct communication (QSDC) protocols are obtained and it is shown that dense coding is not essential for designing of maximally efficient DSQC and QSDC protocols. This fact is used to design maximally efficient protocols of DSQC and QSDC using 3-qubit and 4-qubit W states. 相似文献