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排序方式: 共有258条查询结果,搜索用时 15 毫秒
1.
Neural Computing and Applications - This paper presents an adaptive fuzzy fault-tolerant tracking control for a class of unknown multi-variable nonlinear systems, with external disturbances,... 相似文献
2.
We propose a new position regulation strategy for VTOL-UAVs using IMU and GPS measurements. Since there is no sensor that measures the attitude, our approach does not rely on the knowledge (or reconstruction) of the system orientation as usually done in the existing literature. Instead, IMU and GPS measurements are directly incorporated in the control law. An important feature of the proposed strategy, is that the accelerometer is used to measure the apparent acceleration of the vehicle, as opposed to only measuring the gravity vector, which would otherwise lead to unexpected performance when the vehicle is accelerating (i.e. not in a hover configuration). 相似文献
3.
JanP.K. Reynhardt Yong Yang Abdelhamid Sayari Howard Alper 《Advanced Synthesis \u0026amp; Catalysis》2005,347(10):1379-1388
Polyamidoamine (PAMAM) dendrimers up to the third generation were grown for the first time on the surface of a large‐pore (18 nm) Davisil silica support. The supported dendrimers of generations 0, 1, 2 and 3 were phosphinomethylated and complexed with rhodium. All the generations were found to be very active for the hydroformylation of olefins. The hydroformylation of 1‐octene was accomplished with a turnover frequency of 1700 h−1 at 70 °C. The G(1) material was found to be the most active when the different generations were compared at 50% conversion at 70 °C 相似文献
4.
This work presents a valorization of a solid waste originating from an edible oil refinery called spent bleaching earth (SBE). The SBE material is first impregnated with an ammonium chloride solution (3 M), then treated directly in furnace at 400 °C during an hour followed by a washing in the cold by HCl 1 M. To elucidate the changes in its crystalline structure, induced by the regeneration method, the obtained material (RSBE) is characterized by several physicochemical methods (X-ray diffraction, FTIR, thermal analysis, BET and SEM). The characterization results show that the heat treatment in furnace and the chemical treatment (decomposition of NH4Cl) don’t affect the structure of montmorillonite of regenerated material (RSBE). The study of porous texture by the nitrogen adsorption technique at −196 °C shows that the specific surface area SBET and the pore volume increased in the RSBE material compared to those of virgin bleaching earth VBE (unused) and their values are respectively of 145.68 against 115.5 m2 g−1 and of 0.287 against 0.234 cm3 g−1. Calculations by the adsorption equations using BJH method, applied to both materials, show that the treatment generate an increase in the micropores in the RSBE material. We belonged the values of the micropores area of Smic = 41.98 cm2 g−1 and of Vmic = 0.074 cm3 g−1 for the volume. 相似文献
5.
Hikmat El Ajaltouni Azzedine Boukerche Abdelhamid Mammeri 《Mobile Networks and Applications》2013,18(6):814-830
One of the most challenging issues facing vehicular networks lies in the design of an efficient MAC protocol due to the mobile nature of nodes and the interference associated with the dynamic environment. Moreover delay constraints for safety applications add complexity and latency requirements to the design. Existing MAC protocols overcome some challenges however don’t provide an integrated solution. Hence, the merit if this work lies in designing an efficient MAC protocol that incorporates various VANet’s challenges in a complete end-to-end solution. In this work, we propose an efficient Multichannel QoS Cognitive MAC (MQOG). MQOG assesses the quality of channel prior to transmission employing dynamic channel allocation and negotiation algorithms to achieve significant increase in channel reliability, throughput and delay constraints while simultaneously addressing Quality of Service. The uniqueness of MQOG lies in making use of the free unlicensed bands. The proposed protocols were implemented in OMNET++ 4.1, and extensive experiments demonstrated a faster and more efficient reception of safety messages compared to existing VANet MAC Protocols. Finally, improvements in delay, packet delivery ratios and throughput were captured. 相似文献
6.
Sheng-Zhen Zu Li-Juan Mao Abdelhamid Sayari Bao-Hang Han 《Journal of Porous Materials》2012,19(5):745-749
We here report a facile synthesis route to monodispersed platelet-like SBA-15 mesoporous silica employing kinetically controlled micelles as templates. In previous preparations of SBA-15 silica, it was believed that thermodynamically equilibrated micelles were used as templates. The kinetically controlled micelle has never been used before to generate periodic mesoporous materials with unique morphology. Monodispersed hexagonal platelet-like SBA-15 microparticles were prepared via a very facile synthesis route by tuning the micelle formation process, i.e. the stirring rate and the time of dissolution of the triblock copolymer and formation of the micelles. Shorter micelle formation time and faster stirring are essential to generate platelet-like SBA-15 silica particles. It is expected to apply in the synthesis of a wide variety of mesophase materials. 相似文献
7.
Unexploited Thapsia garganica,Orlaya maritima,and Retama raetam Seeds: Potential Sources of Unsaturated Fatty Acid and Natural Antioxidants 下载免费PDF全文
Nizar Tlili Houda Mejri Houda Ben Lajnef Anouer Feriani Abdelhamid Khaldi Nizar Nasri 《Journal of the American Oil Chemists' Society》2015,92(8):1175-1181
Total lipid contents, fatty acid compositions, phenolic profiles and antioxidants activities of seeds from Thapsia garganica, Orlaya maritima, and Retama raetam were investigated. The oil values were more than 26 %, except seeds of R. raetam (ca. 3 %). Unsaturated fatty acids accounted for the majority of the fatty acids (more than 75 %). Oleic and linoleic acid were the predominant fatty acids. Total phenolic compounds (24–104 mg GAE g?1 DR), total flavonoids (4–102 mg QE g?1g DR), total tannins (28–85 mg GAE g?1 DR) and condensed tannins (0.62–131 mg CE g?1 DR) were also determined. The antioxidant activities using different assays were evaluated. The predominant detected classes were the phenolic acids (42–85 %) and the flavonoids (11–48 %). The major phenolic acids were caffeic, trans‐4‐hydroxy‐3‐methoxycinnamic, p‐coumaric, and gallic acid. The predominant flavonoids were quercetin, luteolin, naringin, apigenin, and kaempferol. This study brings attention to the medicinal importance of these species as a source of oil and antioxidant molecules. 相似文献
8.
Blast furnace slags as functional fillers on rheological,thermal, and mechanical behavior of thermoplastics 下载免费PDF全文
Abdelhamid Mostafa Stephan Laske Gernot Pacher Clemens Holzer Helmut Flachberger Elke Krischey Bertram Fritz 《应用聚合物科学杂志》2016,133(8)
Blast furnace slags (BFS) is a secondary byproduct of iron industry, which has a combination of acidic and basic oxides and show a complex, multiphase structure. If appropriately tailored, BFS could be an effective functional filler, improving the property profile of thermoplastics such as polypropylene (PP) and polystyrene (PS). As a raw material, the proposed filler may introduce both economic and ecological advantages, as it is considered an inexpensive secondary product rather than a natural resource. The current study aims at investigating the effect of incorporating BFS as a micro‐sized filler on the rheological, thermal, and mechanical behavior of PP and PS. BFS types in this study are air‐cooled, crystalline, and amorphous, grounded types. Both types are ground into 71, 40, and 20 μm batches and introduced in 10, 20, and 30 weight fractions via melt kneading. Mixtures are then formed into 4‐mm and 2‐mm thick plates via compression molding. Slight increase in rheological factors is observed with increasing filler loading. BFS hinders the crystallization of PP, resulting in slight increase of crystallization temperatures (Tc) and lowering of crystallization enthalpy (ΔHc). No significant effect of filler on transition temperatures (Tg) is reported. Mechanically, BFS increases the tensile modulus of PP, but decreases its strength. For PS formulations, a modest toughening effect is observed by slag filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43021. 相似文献
9.
10.
Abdou O. Abdelhamid Abdalla M. Negm Ikhlass M. Abbas 《Advanced Synthesis \u0026amp; Catalysis》1989,331(1):31-36
Phenacylmalononitriles 2 react with hydrazines, acetic-hydrochloric acid and with diazotised primary aromatic amines to afford phenacylpyrazole ( 5a,b ), aminofurans ( 6a,b ) and aminopyrazole derivatives ( 3a,d ) respectively. The synthesised derivatives ( 3d, 6a ) were the key materials for the synthesis of isoindolinedione, ( 7a – c ) pyrazolopyrimidine ( 9, 10 ), and pyrazolopyridazine derivatives ( 11 ). The structures of the newly synthesised heterocycles were established on the basis of elemental analyses and spectral data besides synthesis via other routes. 相似文献