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141.
142.
Tarek Agag Carlos R. Arza Frans H. J. Maurer Hatsuo Ishida 《Journal of polymer science. Part A, Polymer chemistry》2011,49(20):4335-4342
Two types of main‐chain type polybenzoxazines with amide and benzoxazine groups as repeating units in the main chain, termed as poly(amide‐benzoxazine), have been synthesized. They have been prepared by polycondensation reaction of primary amine‐bifunctional benzoxazine with adipoyl and isophthaloyl dichloride using dimethylacetamide as solvent. Additionally, a model reaction is designed from the reaction of 3,3′‐(4,4′‐methylenebis(4,1‐phenylene))bis(3,4‐dihydro‐2H‐benzo[e][1,3]oxazin‐6‐amine) with benzoyl chloride. The structures of model compound and polyamides are confirmed by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopies. Differential scanning calorimetry and FTIR are also used to study crosslinking behavior of both the model compound and polymers. Thermal properties of the crosslinked polymers are also studied by thermogravimetric analysis. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
143.
Tarek R. Sheltami Anas A. Al-Roubaiey Ashraf S. Hasan Mahmoud 《Wireless Networks》2016,22(6):2049-2070
Publish/subscribe (Pub/Sub) interaction paradigm is receiving more attention in commercial and academic research nowadays. It is an effective interaction scheme for large-scale distributed systems due to its ability of decoupling communicating entities in time, space, and synchronization. The decoupling properties are well-suited for Wireless Sensor Network (WSN) applications because of their special characteristics such as data-centricity, dynamicity, and many-to-many communications. Many studies have been conducted to adapt Pub/Sub communication model to WSN. In this paper, we review the Pub/Sub interaction paradigm in the context of WSN. Moreover, we classify, analyze and synthesize different Pub/Sub based solutions proposed recently for WSN and discuss the open problems and new research directions in this area. Also, we propose a new reference model for pub/sub middleware in wireless sensor and actuator networks. To the best of our knowledge this is the first survey on this specific subject. 相似文献
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Combinations of N-halosuccinimide and tetrachlorosilane in acetonitrile were found to be efficient systems for the selective α-monohalogenation of carbonyl compounds as well as for benzylic halogenation under mild conditions. 相似文献
147.
Lutful Karim Nidal Nasser Tarek Sheltami 《Wireless Communications and Mobile Computing》2014,14(2):175-185
Energy efficiency in specific clustering protocols is highly desired in wireless sensor networks. Most existing clustering protocols periodically form clusters and statically assign cluster heads (CHs) and thus are not energy efficient. Every non‐CH node of these protocols sends data to the CH in every time slot of a frame allocated to them using the time division multiple access scheme, which is an energy‐consuming process. Moreover, these protocols do not provide any fault tolerance mechanism. Considering these limitations, we have proposed an efficient fault‐tolerant and energy‐efficient clustering protocol for a wireless sensor network. The performance of the proposed protocol was tested by means of a simulation and compared against the low energy adaptive clustering hierarchy and dynamic static clustering protocols. Simulation results showed that the fault‐tolerant and energy‐efficient clustering protocol has better performance than both the low energy adaptive clustering hierarchy and dynamic static clustering protocols in terms of energy efficiency and reliability. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
148.
Siham Benkouda Mounir Amir Tarek Fortaki Abdelmadjid Benghalia 《Journal of Infrared, Millimeter and Terahertz Waves》2011,32(11):1350-1366
The dual-frequency behavior of stacked high T
c
superconducting rectangular microstrip patches fabricated on a two-layered substrate is investigated using a full-wave spectral
analysis in conjunction with the complex resistive boundary condition. Using a matrix representation of each layer, the dyadic
Green’s functions of the problem are efficiently determined in the vector Fourier transform domain. The stationary phase method
is used for computing the radiation electric field of the antenna. The proposed approach is validated by comparison of the
computed results with previously published data. Variations of the lower and upper resonant frequencies, bandwidth and quality
factor with the operating temperature are given. Results showing the effects of the bottom patch thickness as well as the
top patch thickness on the dual-frequency behavior of the stacked configuration are also presented and discussed. Finally,
for a better comprehension of the dual-frequency operation, a comparison between the characteristics of the lower and upper
resonances is given. 相似文献
149.
Abd El‐Wareth A. O. Sarhan Shams H. Abdel‐Hafez Hassan El‐Sherief Tarek Aboel‐Fadl 《合成通讯》2013,43(8):987-996
The utilities of the Mannich reaction in synthetic organic chemistry are reviewed. The behaviors of Mannich reactions on several bifunctional heterocyclic compounds have been reported. A new class of heterocyclic compounds, thiadiazino[1,3,5][3,2‐a]benzimidazoles 12a–g, were obtained by reaction of 2‐mercaptobenzimidazole with primary aliphatic amines in a one‐step synthesis. An attempt to apply this reaction using primary aromatic amines lead to the formation of the well‐known Mannich bases 11a–g rather than the N‐substituted thiadiazines 13. 相似文献
150.
Shafeek A.R. Mulla Tarek A. Salama Mohsinkhan Y. Pathan Suleman M. Inamdar Santosh S. Chavan 《Tetrahedron letters》2013,54(7):672-675
A solvent-free, environmentally clean, mild, and simple one-pot multi-component protocol has been developed for the efficient synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols in excellent yields via one-pot three-component condensation of various aldehydes, amides/carbamates/urea, and naphthols/phenols using ethylammonium nitrate (EAN) as a reusable ionic liquid catalyst under neat reaction condition at ambient temperature. 相似文献