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61.
In the last few years, the development of wireless local area networks (WLANs) has become a major goal in the field of computer and wireless communications. The Network Technologies Research group at the Communications Research Center in Canada has been working on a project to develop a high speed outdoor WLAN. In contrast to many existing WLANs, the new WLAN supports multimedia traffic such as voice, data and video; and will be used mainly in an outdoor environment with a cell coverage range of approximately 20 km. In this paper the physical layer design alternatives for the outdoor WLAN with a speed of 10 to 20 Mbps are described. Simulation results for some of the techniques considered to be used for the WLAN system are presented. The study is concluded by proposing two possible systems that one may consider for the implementation of a high speed outdoor WLAN. Although this study was primarily focused on WLAN applications, the results presented in this paper are applicable to several high speed wireless networks. 相似文献
62.
A. Smida R. Ghayoula N. Nemri H. Trabelsi A. Gharsallah D. Grenier 《International Journal of Communication Systems》2014,27(12):4449-4466
Phased antenna array design is one of the most important electromagnetic optimization problems. This research combined the Taguchi method and artificial intelligence methods, used them as the prediction tool in designing parameters for the communication system, and then constructed a set of the optimal parameter analysis flow and steps. In this paper, we present an application of artificial neural networks in the electromagnetic domain. We particularly look at the multilayer perceptron network, which has been the most used of artificial neural networks architectures both in the electromagnetic domain and in the Taguchi optimization technique and describes the Taguchi method to optimize the excitations elements of the linear array to produce a radiation pattern with minimum side lobe level and null placement control. This paper investigates how the implementation of the signal processing in hardware affects the performance of the adaptive array antenna. The investigation is confined to uplink or receive antenna array only. Results of a prototype of antenna array with feeding values designed using the proposed techniques are also presented. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
63.
64.
A Greffard N Trabelsi H Terzidis J Bignon MC Jaurand Y Pilatte 《Canadian Metallurgical Quarterly》1997,1334(2-3):140-148
Sulfated glycosaminoglycans are known to inhibit mammalian acid-active sialidase. Although the inhibition depends clearly on the presence of sulfate groups on these macromolecules, there was no information on the intrinsic inhibitory potency of inorganic sulfate. In this study, we demonstrate that inorganic sulfates inhibit acid-active Mu-Neu5Ac sialidase of U937 cells. This inhibition was found to be reversible and it appeared to be of the mixed competitive type. Sulfate-induced inhibition was also observed in other cells as well as with other substrates such as sialyl lactose and bovine mixed brain gangliosides. We conclude that the intrinsic inhibitory potency of sulfate groups may be significantly involved in the inhibition of acid-active sialidase by sulfated glycosaminoglycans. In addition, inorganic sulfate by its apparent potency to selectively inhibit acid sialidases might constitute an interesting tool for the characterisation of the minor forms of sialidases occurring in mammalian cells. 相似文献
65.
H. Trabelsi E. Kannatey-Asibu Jr. 《The International Journal of Advanced Manufacturing Technology》1991,6(3):220-231
Pattern-recognition analysis of sound radiation was developed as a basis for monitoring the metal-cutting process. The sound-pressure
signals radiated during cutting under fixed conditions were recorded using a sharp tool, a worn tool and a broken tool. A
round bar of heat-treated AISI 4340 steel was machined in cylindrical turning, using a titanium-carbide-coated cutting tool.
The spectral components in the 0–10 kHz range were used as features. Using resubstitution, signals coming from sharp and worn
tools were easily distinguished, resulting in a 100% classification with just two features, being the average of the low (0–5
kHz) and high (5–10 kHz) frequency ranges. With tool breakage, two acceptable classifications were obtained using independent
testing, the first with a performance of 100%, 75% and 100% for sharp, worn and breakage signals respectively, using nine
features, and the second with 80%, 88% and 80%, using eight features. 相似文献
66.
Wireless Networks - Using efficiently the wireless sensor networks based on IEEE 802.15.4/zigbee remains a real challenge for the forest fire detection and monitoring applications. The most... 相似文献
67.
68.
Trabelsi Youssef Ali Naim Ben Alsaif Haitham Kahouli Omar Kanzari Mounir 《Journal of Superconductivity and Novel Magnetism》2022,35(9):2311-2317
Journal of Superconductivity and Novel Magnetism - In this numerical simulation, we study a new optical device based on semiconductor-superconductor structures, showing narrower broadband... 相似文献
69.
khemakhem Olfa Naceur Jamila Ben Ayadi Firas Cheikhrouhou-Koubaa Wissem Koubaa Mohamed Nachbaur Virginie Chtourou Radhouane Cheikhrouhou Abdelwaheb 《Journal of Superconductivity and Novel Magnetism》2022,35(11):3371-3378
Journal of Superconductivity and Novel Magnetism - Hard hexagonal barium ferrite BaFe12O19 (BaM), as well as core–shell structure BaFe12O19-TiO2 composite nanoparticles, was successfully... 相似文献
70.
Salah Selmi Nawzet Bouriga Mourad Cherif Mohsen Toujani Monia Trabelsi 《International Journal of Food Science & Technology》2010,45(6):1161-1168
Changes in biochemical and microbiological quality of silverside during two drying process were investigated. Total fatty acid and amino acid contents in silverside were 5.42 and 10.9 g 100 g?1 fresh sample, respectively, in which, palmitic acid and glutamic acid were the most abundant. N‐3 and n‐6 polyunsaturated fatty acids (PUFA) levels were 0.59 and 0.62 g 100 g?1 fresh silverside respectively. After hot air and solar drying treatments, Peroxide value and thiobarbituric acid reactive substances of the total lipids increased significantly (P < 0.05) to reach 2.58 and 3.41 meq active O2 kg?1 oil and 0.87 and 1.27 mg MA kg?1 oil, respectively. Fatty acid profile of non‐polar lipid remains unchanged during experimental drying process. However, PUFA (% of total fatty acids) of polar lipid decreased significantly (P < 0.05) during both drying process with lower levels in solar drying process. Drying conditions had a significant effect on the microbiological quality. Therefore, mesophiles and total coliforms increased within drying treatment with higher counts in solar drying process. 相似文献