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81.
Electron spin resonance studies have been carried out on Cu2+ ion doped in single crystals of cadmium maleate dihydrate at 303 and 77K. It has been found that Cu2+ enters this lattice interstitially. The spin Hamiltonian parameters have been evaluated and the ground state wave function
is found to be predominantly |X
2 −Y
2〉 with a slight admixture of |3Z
2 −r
2〉. 相似文献
82.
83.
U. Dadwal R. Scholz M. Reiche P. Kumar S. Chandra R. Singh 《Applied Physics A: Materials Science & Processing》2013,112(2):451-456
GaN epitaxial layers were implanted by 100 keV H+ ions at different implantation temperatures (LN2, RT and 300 °C) with a fluence of 2.5×1017 cm?2. The implanted samples were characterized using Nomarski optical microscopy, AFM, XRD, and TEM. Topographical investigations of the implanted surface revealed the formation of surface blistering in the as-implanted samples at 300 °C and after annealing at higher temperature for the implantation at LN2 and RT. The physical dimensions of the surface blisters/craters were dependent on the implantation temperature. XRD showed the dependence of damage-induced stress on the implantation temperature with higher stress for the implantation at 300 °C. TEM investigations revealed the formation of a damage band in all the cases. The damage band was filled with large area microcracks for the implantation at 300 °C, which were responsible for the as-implanted surface blistering. 相似文献
84.
Influence of power-law index on transitional Reynolds numbers for flow over a semi-circular cylinder
In this work, the governing partial differential equations (continuity and Cauchy’s momentum equations) describing the flow of power-law type non-Newtonian fluids across a semi-circular cylinder (oriented with its curved surface in the upstream direction) have been solved numerically. In particular, consideration has been given to the delineation of the critical Reynolds numbers denoting the onset of flow separation from the surface of the cylinder and the onset of the laminar vortex shedding regime. This information is germane to establish the scaling of the macroscopic characteristics like drag coefficient and Strouhal number on the governing parameters, namely, Reynolds number and power-law index. The present results clearly suggest that the transitional Reynolds numbers show a strong dependence on the type (shear-thinning and shear-thickening) of fluid behavior as well as on the severity of the shear-dependence of the viscosity. With reference to the behavior seen in Newtonian fluids, the flow remains not only attached to the surface up to higher Reynolds numbers, but shear-thinning behavior also delays the onset of the laminar vortex shedding regime. As expected, shear-thickening fluids, of course, display the opposite characteristics. 相似文献
85.
Sayantani Das Alo Dutta Binita Ghosh Sourish Banerjee T.P. Sinha 《Journal of Physics and Chemistry of Solids》2014
Nanoparticles of cadmium selenide (CdSe) have been synthesized by soft chemical route using mercaptoethanol as a capping agent. X-ray diffraction and transmission electron microscope measurements show that the prepared sample belongs to sphalerite structure with the average particle size of 25 nm. The band gap of the material is found to be 2.1 eV. The photoluminescence (PL) emission spectra of the sample are measured at various excitation wavelengths. The PL spectra appear in the visible region, and the emission feature depends on the wavelength of the excitation. Impedance spectroscopy is applied to investigate the dielectric relaxation of the sample in a temperature range from 323 to 473 K and in a frequency range from 42 Hz to 1.1 MHz. The complex impedance plane plot has been analyzed by an equivalent circuit consisting of two serially connected R-CPE units, each containing a resistance (R) and a constant phase element (CPE). The dielectric relaxation of the sample is investigated in the electric modulus formalism. The temperature dependent relaxation times obey the Arrhenius law. The Havriliak–Negami model is used to investigate the dielectric relaxation mechanism in the sample. The frequency dependent conductivity spectra are found to obey the power law. 相似文献
86.
Arun Aravind K. Hasna M. K. Jayaraj Mukesh Kumar Ramesh Chandra 《Applied Physics A: Materials Science & Processing》2014,115(3):843-849
Phase pure Zn1?x Co x O thin films grown by pulsed laser deposition have transmittance greater than 75 % in the visible region. Raman studies confirm the crystalline nature of Zn1?x Co x O thin films. Zn0.95Co0.05O thin films show room temperature ferromagnetism with saturation magnetization of 0.4μ B /Co atom. The possible origin of paramagnetism at higher Co doping concentrations can be attributed to the increased nearest-neighbor antiferromagnetic interactions between Co2+ ions in ZnO matrix. XPS confirms the substitution of Co2+ ions into the ZnO host lattice. 相似文献
87.
A study of damping in fiber-reinforced composites 总被引:1,自引:0,他引:1
Damping contributions from the viscoelastic matrix, interphase and the dissipation resulting from damage sites are considered to evaluate composite material damping coefficients in various loading modes. The paper presents the results of the FEM/Strain energy investigations carried out to predict anisotropic-damping matrix comprising of loss factors η11, η22, η12 and η23 considering the dissipation of energy due to fiber and matrix (two phase) and correlate the same with various micromechanical theories. Damping in three phase (i.e., fiber-interphase-matrix) composite is also calculated as an attempt to understand the effect of interphase. The contribution of energy dissipation due to sliding at the fiber-matrix interface is incorporated to evaluate its effect on η11, η22, η12 and η23 in fiber-reinforced composite having damage in the form of hairline debonding. Comparative studies of the various micromechanical theories/models with FEM/Strain energy method for the prediction of damping coefficients have shown consistency when both the effect of variable nature of stress and the fiber interaction is considered. Parametric damping studies for three phase composite have shown that the change in properties of fiber, matrix and interphase leads to a change in the magnitude of effectiveness of interphase, but the manner in which the interphase would affect the various loss factors depends predominately upon whether the hard or soft interphase is chosen. Analysis of the effect of damage on composite damping indicates that it is sensitive to its orientation and type of loading. 相似文献
88.
89.
Reshma Khemchandani Nishil Gupta Arpit Chaudhary Suresh Chandra 《Optimization Letters》2013,7(3):575-592
In this paper, we develop optimal trading strategies for a risk averse investor by minimizing the expected cost and the risk of execution. Here we consider a law of motion for price which uses a convex combination of temporary and permanent market impact. In the special case of unconstrained problem for a risk neutral investor, we obtain a closed form solution for optimal trading strategies by using dynamic programming. For a general problem, we use a quadratic programming approach to get approximate dynamic optimal trading strategies. Further, numerical examples of optimal execution strategies are provided for illustration purposes. 相似文献
90.
Subhash Chandra S. Annapoorni R. G. Sonkawade P. K. Kulriya Fouran Singh D. K. Avasthi J. M. S. Rana R. C. Ramola 《Indian Journal of Physics》2009,83(7):943-947
High-energy ion beam irradiation of the polymers is a good technique to modify the properties such as electrical conductivity,
structural behaviour and mechanial properties. Polyaniline thin films doped with hydrochloric acid (HCl) were prepared by
oxidation of ammonium persulphate. The effect of Swift Heavy Ions irradiation on the electrical and structural properties
of polyaniline has been measured in this study. Polyaniline films were irradiated by oxygen ions (energy 80 MeV, charge state
O+7) with fluence varying from 1 × 1010 to 3 × 1012 ions/cm2. The studies on electrical and structural properties of the irradiated polymers were investigated by measuring V-I using
four probe set-up and X-ray diffraction (XRD) using Bruker AXS, X-ray powder diffractometer. V-I measurements shows an increase
in the conductivity of the film, XRD pattern of the polymer shows that the crystallinity improved after the irradiation with
Swift Heavy Ions (SHI), which could be attributed to cross linking mechanism.
相似文献