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91.
D. N. Elsheakh H. A. Elsadek E. A. Abdallah M. F. Iskander H. Elhenawy 《Applied Physics A: Materials Science & Processing》2011,103(3):541-545
Three novel shapes of mushroom-like electromagnetic bandgap (EBG) structures are presented in this paper. The three shapes
are based on a rectangular metal strip with different combinations. The performances of the three-shape structures are studied
by using both an incident plane wave method and transmission coefficient approach. The effect of height and via location is
also studied to achieve multi or wide bandgap. These shapes are embedded in microstrip patch antenna substrates. The performance
of the MPA is improved as increasing the antenna gain by 5 dBi, decreasing the surface current so improving the antenna radiation
pattern as well as reducing the antenna size by more than 70% compared to the original size. The new shapes of EBG structures
are integrated with MPA as a ground plane, where the conducting ground plane is replaced by a high impedance surface EBG layer.
Parametric studies are conducted to maximize their impedance bandwidth and gain. It is found that the antenna bandwidth increased
by approximately four times than the original band and its gain is similarly increased. Sample of these antennas are fabricated
and tested to verify the designs. 相似文献
92.
In the electronic industry, dissipating the heat load becomes a critical factor for highly developed designs. These require higher power transfer in a more compact size. In the current study, a new microcooling system was developed and tested. It utilizes the enhancement in heat transfer characteristics associated with implementing a vortex promoter in the evaporator segment of a water-based heat pipe. The test evaporator was a cavity of 4-mm diameter and 23-mm length in an electrically heated aluminum block. A helical coil (of various diameters, namely 500, 300, and 250 μm) was introduced to the evaporator segment to act as a vortex promoter. Configurations of a new microcooling system based on a modified heat pipe technology were built and tested. The presented system proves to work efficiently in situations where a closed-loop thermosyphon encounters film boiling limitation. The most efficient configuration has a flow modifier diameter about one-tenth of the evaporator chamber gap, while the diameter of the return line was three-quarters of the evaporator gap. This configuration shows a stable operation characteristic and possesses high thermal efficiency. The maximum heat flux obtained by such a configuration was 305 W/cm2 when it runs at 103°C saturated temperature and 0.01°C/W thermal resistance. A uniform temperature distribution along the system was noticed. 相似文献
93.
Marat Faizrahmanov Asher Kach Iskander Kalimullin Antonio Montalbn Vadim Puzarenko 《Mathematical Logic Quarterly》2019,65(1):37-45
It is proved that for every countable structure and a computable successor ordinal α there is a countable structure which is ‐least among all countable structures such that is Σ‐definable in the αth jump . We also show that this result does not hold for the limit ordinal . Moreover, we prove that there is no countable structure with the degree spectrum for . 相似文献
94.
Kerehalli Vinayaka Prasad Hanumesh Vaidya Fateh Mebarek Oudina Khalid Mustafa Ramadan Muhammad Ijaz Khan Rajashekhar Choudhari Rathod Kirankumar Gulab Iskander Tlili Kamel Guedri Ahmed M. Galal 《印度化学会志》2022,99(8):100617
Due to the illuminating function of nanoliquids in several technological and medicinal domains, particularly in liquid transport processes known as peristalsis, inquisitive researchers have investigated the flow of peristaltic nanofluids. Consequently, the current study investigates the entropy production and magnetic influence on the peristaltic transport of heat and mass transport of Casson nanofluid in a non-uniform channel under convective circumstances. Utilizing the perturbation approach, fields of concentration, temperature, and velocity are derived from non-linear coupled partial differential equations (PDE). Entropy generation studies have been done. In addition, the influence of associated factors via specific physical terms, including the Sherwood number, the skin-friction coefficient, and the Nusselt number, for both Casson and Newtonian liquids, as well as the trapping phenomena, is visually examined. 相似文献
95.
Abdelmalek Zahra Khan Sami Ullah Awais Muhammad Mustfa Muhammad Salman Tlili Iskander 《Journal of Thermal Analysis and Calorimetry》2021,144(3):1051-1063
Journal of Thermal Analysis and Calorimetry - A fundamental interest has been developed in the twenty-first century toward the significance of nanoparticles due to decisive applications in various... 相似文献
96.
A. V. Golenishchev-Kutuzov V. A. Golenishchev-Kutuzov R. I. Kalimullin A. V. Semennikov 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(5):515-517
Using tightly focused laser beams, features of space charge fields (~107 V/m) are studied through the photoionization of doped Jahn–Teller Fe2+ ions in LiNbO3 single crystals. These fields can be used for selective formation of the inverse domain state following the additional application of a field with a strength below the coercive field. The characteristics of laser-induced domains and periodic domain structures are studied by laser-acoustic means. 相似文献
97.
George Iskander 《Tetrahedron letters》2009,50(32):4613-4615
A versatile method for the synthesis of novel brominated 4-alkyl-2(5H)-furanones under mild reaction conditions is described. This synthetic strategy requires only one chromatographic separation over six steps and employs the cyclodehydration of brominated levulinic acid as the key transformation. 相似文献
98.
Samuel K. Kutty George Iskander Renate Griffith Naresh Kumar 《Tetrahedron letters》2010,51(37):4856-3016
A series of novel fimbrolide disulfanes is synthesized and a crystal structure analysis reveals interesting inter-molecular halogen-bonding and CO?CO (carbonyl-carbonyl) dipolar interactions. Molecular modelling studies with the target protein display significant halogen-bonding interactions in the ligand -binding site. 相似文献
99.
David K. Chalmers Sharon L. A. Munro Magdy N. Iskander David J. Craik 《Journal of computer-aided molecular design》1992,6(1):19-31
Summary The antiarrhythmic drug amiodarone has recently been characterized as the first known thyroid hormone antagonist. Its mode of interaction with the thyroid hormone receptor is therefore of interest. A computational analysis of the conformational flexibility of amiodarone using molecular mechanics and the semiempirical molecular orbital method AM1 has been performed. The molecular mechanics studies show that the low-energy conformations of the benzoylbenzofuran portion of amiodarone can be grouped into 4 distinct classes, while the diethylaminoethoxy side chain is extremely flexible. Conformers representative of the 4 low-energy classes were fitted to an extended thyroid hormone receptor model. Four independent modes in which amiodarone could bind to the thyroid hormone receptor site were evaluated. 相似文献
100.