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41.
Ijaz A. Bhatti Shahid Adeel M. Asghar Jamal Muhammad Safdar Muhammad Abbas 《Radiation Physics and Chemistry》2010,79(5):622-625
The effect of gamma radiation on the dyeing of cotton with extract of turmeric (Curcuma longa L.) powder has been investigated. Cotton fabric and turmeric powder were irradiated to absorbed doses of 1, 2, 3, 4 and 6 kGy using Co-60 gamma irradiator. Dyeing parameters such as temperature, pH and mordant concentration were optimized. Dyeing was performed using un-irradiated and irradiated cotton with the extracts of un-irradiated and irradiated turmeric powder in order to investigate the effect of radiation treatment on the colour strength of dyed fabric. The reported data of un-irradiated and irradiated fabrics dyed with un-irradiated and irradiated dyes were obtained using the spectraflash SF-650. The colourfastness to light, rubbing- and washing-fastness properties showed that gamma irradiation has improved the dyeing characteristics from fair to good. 相似文献
42.
The lifetime of electrostatically trapped indirect excitons in a field-effect structure based on coupled AlGaN/GaN quantum wells has been theoretically studied. Within the plane of a double quantum well, indirect excitons are trapped between the surfaces of the AlGaN/GaN heterostructures and a semitransparent metallic top gate. The trapping mechanism has been assumed to be a combination of the quantum confined Stark effect and local field enhancement. In order to study the trapped exciton lifetime, the binding energy of indirect excitons in coupled quantum wells is calculated by finite difference method in the presence of an electric field. Thus, the lifetime of trapped excitons is computed as a function of well width, AlGaN barrier width, the position of double quantum well in the device and applied voltage. 相似文献
43.
Fission cross sections strongly depend on the ratio of the level density parameter in fission to neutron emission, af/an. In this work, a cascade-exciton model implemented in the code CEM95 has been used to observe this effect for proton induced fission cross sections of tungsten, lead and bismuth. The method was employed using different level density parameter ratios for each fission cross section calculation. The calculated fission cross sections are compared with the available experimental data in the literature. It has been observed that a change of the ratio of the level density parameter, af/an, is necessary with the incident energy of the proton, to best estimate the fission cross sections in CEM95. 相似文献
44.
Jeroen D.C. Codée Asghar Ali Herman S. Overkleeft Gijsbert A. van der Marel 《Comptes Rendus Chimie》2011,14(2-3):178-193
Protecting groups play a pivotal role in carbohydrate chemistry. This review describes a selection of protecting groups and protecting group strategies that have been introduced since the beginning of this century. 相似文献
45.
The multigrid method is one of the most efficient techniques for convergence acceleration of iterative methods. In this method, a grid coarsening algorithm is required. Here, an agglomeration scheme is introduced, which is applicable in both cell‐center and cell‐vertex 2 and 3D discretizations. A new implicit formulation is presented, which results in better computation efficiency, when added to the multigrid scheme. A few simple procedures are also proposed and applied to provide even higher convergence acceleration. The Euler equations are solved on an unstructured grid around standard transonic configurations to validate the algorithm and to assess its superiority to conventional explicit agglomeration schemes. The scheme is applied to 2 and 3D test cases using both cell‐center and cell‐vertex discretizations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
46.
The heat transfer analysis on the laminar flow of an incompressible third grade fluid through a porous flat channel is examined. The lower plate is assumed to be at a higher temperature than the upper plate. Analytical solution for temperature distribution is obtained for various values of the controlling parameters and discussed. The obtained analytical solution is also compared with the numerical solution. The comparison shows the fact that the accuracy is remarkable. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
47.
J. P. Bocquet R. Brissot H. R. Faust M. Fowler J. Wilhelmy M. Asghar M. Djebara 《Zeitschrift für Physik A Hadrons and Nuclei》1990,335(1):41-48
The mass and nuclear charge distributions of fission fragments from229Th(nth, f) have been measured at several kinetic energies with the mass spectrometer Lohengrin (ILL-Grenoble). The average proton e-o effect, which reaches 41%, induces large oscillations in the parameters of the isotopic charge distribution. A comparison of the data from different fissile nuclei shows the importance of the last stage of the process for intrinsic excitations. 相似文献
48.
Flow and heat transfer over a permeable sensor surface placed in a squeezing channel is analyzed. A constant transpiration
through the sensor surface is assumed. Locally non-similar momentum and energy equations are solved by three different methods,
against the transpiration parameter τ, for different values of the squeezing parameter b, and Prandtl number Pr. From the investigation, it is found that when the channel being squeezed, the skin-friction reduces but the heat transfer
coefficient increases. Increase in the value of the squeezing parameter onsets reverse flow at the sensor surface when fluid
is being injected and the affect is enhanced with the increase of injection through the surface. It is further observed that
increase of suction of fluid through the sensor thins the thermal and the momentum boundary layer regions, whereas injection
of fluid leads to thickening of both the thermal and the momentum boundary layer regions. Heat transfer from the surface of
the sensor increases with the increase of the value of Pr for the entire range of surface mass-flux parameter τ.
M. A. Hossain is on leave of absence from University of Dhaka. 相似文献
49.
The convective instability of a horizontal liquid layer confined in an annular Hele–Shaw cell subject to a constant rotation and submitted to a centrifugal gradient of temperature is investigated. Using a linear stability analysis, we study the effects of both Coriolis forces and curvature aspect on the stationary convective threshold when the Prandtl number is of the order of unity or larger than unity. We show that the Coriolis forces have a stabilizing effect, and the wave number is independent of these forces. However, a multicellular regime in the radial direction is observed for small Ekman numbers. The results related to the influence of the curvature are also shown. To cite this article: S. Ramezani et al., C. R. Mecanique 330 (2002) 633–640. 相似文献
50.
Arash Bahrami Asghar Nosier 《International Journal of Solids and Structures》2007,44(25-26):8119-8142
Within the elasticity formulation the most general displacement field for hygrothermal problems of long laminated composite plates is presented. The equivalent single-layer theories are then employed to determine the global deformation parameters appearing in the displacement fields of general cross-ply, symmetric, and antisymmetric angle-ply laminates under thermal and hygroscopic loadings. Reddy’s layerwise theory is subsequently used to determine the local deformation parameters of various displacement fields. An elasticity solution is also developed in order to validate the efficiency and accuracy of the layerwise theory in predicting the interlaminar normal and shear stress distributions. Finally, various numerical results are presented for edge-effect problems of several cross-ply, symmetric, and antisymmetric angle-ply laminates subjected to uniform hygrothermal loads. All results indicate high stress gradients of interlaminar normal and shear stresses near the edges of laminates. 相似文献