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61.
Haithem Ben Chikha Slim Chaoui Iyad Dayoub Jean-Michel Rouvaen Rabah Attia 《Wireless Personal Communications》2012,67(4):951-969
In this paper, we investigate a coded cooperation diversity scheme suitable for L-relay channels operating in the soft-decode-and-forward (soft-DF) mode. The proposed scheme is based on parallel concatenated convolutional codes (PCCC). To improve the overall performance through diversity, the coded cooperation operates by sending the systematic and the first parity outputs via L?+?1 independent fading paths. Instead of using only a centralized turbo code system at the source node, we have proposed a DCC scheme, where the first recursive systematic coding is done at both source and relay nodes. At the destination, the received replicas are combined using the maximal ratio combining (MRC). The entire codeword, comprising the MRC sequence and the second parity part, is decoded via the maximum a-posteriori (MAP) algorithm and turbo decoding principle. We analyze the proposed scheme in terms of bit error rate (BER). In fact, we define the explicit upper bounds for error rate assuming Binary phase shift keying (BPSK) transmission for fully interleaved channels with channel state information (CSI). We use the Rayleigh fading channels with independent fading. Our study shows that the full diversity order is achieved when the source-relay link is more reliable than the other links. Otherwise, the diversity decreases. However, in both cases, it is shown that significant performance improvements are possible to achieve over non-cooperative coded systems. Theorical and simulation results are presented to demonstrate the efficacy of the proposed scheme. 相似文献
62.
M. S. Attia A. O. Youssef Abdel-Sattar S. H. Elgazwy Samia A. El Abady Samia M. Agami Safaa I. Elewa 《Journal of fluorescence》2014,24(3):759-765
The sensitization of the excited triplet state of a novel symmetrical Bis(dialkylamino)phenoxazinium salt was developed in the presence of Hg2+. This effect was used to determine the concentration of Hg2+ in different water samples. The phenoxazinium salt sensor was characterized by different spectroscopic tools such as: UV, FTIR, NMR and fluorescence spectra. The sensor has an emission band at 347 nm in DMSO. Hg2+ in DMSO at pH 5.6 can remarkably quench the fluorescence intensity of the sensor at 347 nm and a new band was appeared at 436 nm due to the strong complex formation between Hg2+ and sensor. The quenching of the band intensity at 347 and the enhancement of the intensity of the new band at 436 were used to determine the Hg2+ in different waste water samples. The dynamic range found for the determination of Hg2+ concentration is 8.7?×?10-10 – 1.4?×?10-6 mol L?1 with a detection limit of 5.8?×?10?10 mol L?1 and quantification detection limit of 1.8?×?10-9 mol L-1. 相似文献
63.
Consider an \({\mathbb{R}^d}\) -valued branching random walk (BRW) on a supercritical Galton Watson tree. Without any assumption on the distribution of this BRW we compute, almost surely and simultaneously, the Hausdorff and packing dimensions of the level sets E(K) of infinite branches in the boundary of the tree (endowed with its standard metric) along which the averages of the BRW have a given closed connected set of limit points K. This goes beyond multifractal analysis, which only considers those level sets when K ranges in the set of singletons \({\{\alpha\}, \alpha \in \mathbb{R}^d}\) . We also give a 0–∞ law for the Hausdorff and packing measures of the level sets E({α}), and compute the free energy of the associated logarithmically correlated random energy model in full generality. Moreover, our results complete the previous works on multifractal analysis by including the levels α which do not belong to the range of the gradient of the free energy. This covers in particular a situation that was until now badly understood, namely the case where a first order phase transition occurs. As a consequence of our study, we can also describe the whole singularity spectrum of Mandelbrot measures, as well as the associated free energy function (or L q -spectrum), when a first order phase transition occurs. 相似文献
64.
65.
Biofouling or adsorption of biomolecules onto surfaces in microfluidic devices limits the type of samples which can be handled. In this paper, we take advantage of the high adsorption capacity of graphene oxide (GO) for proteins as a strategy to limit biofouling, while preserving their activity for droplet-based lab-on-chip applications. 相似文献
66.
Perry G Coffinier Y Thomy V Boukherroub R 《Langmuir : the ACS journal of surfaces and colloids》2012,28(1):389-395
This study reports on liquid-repellency of zinc oxide nanostructures (ZnO NS). The ZnO NS are synthesized by an easy and fast chemical bath deposition technique. Three different nanostructured surfaces consisting of nanorods, flowers, and particles are prepared, depending on the deposition time and the presence of ethanolamine in the reaction mixture. Chemical functionalization of the ZnO NS with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (PFTS) in liquid (PFTS L) and vapor phase (PFTS V) or through octafluorobutane (C(4)F(8)) plasma deposition led to the formation of superomniphobic surfaces. A comprehensive characterization of the wetting properties (static contact angle and contact angle hysteresis) has been performed using liquids composed of deionized water and various concentrations of ethanol (surface tension between 35 and 72.6 mN/m). Depending on the nanostructures morphology, coating nature and liquid employed, high static apparent contact angles θ ≈ 150-160°, and low contact angle hysteresis Δθ ≈ 0° are obtained. The different ZnO NS are characterized using scanning electron microscopy (SEM) and contact angle measurements. The results reported in this work permit preparation of sliding omniphobic surfaces using a simple and low cost technique. 相似文献
67.
Wang Q Kromka A Houdkova J Babchenko O Rezek B Li M Boukherroub R Szunerits S 《Langmuir : the ACS journal of surfaces and colloids》2012,28(1):587-592
In this article, we report on the low-level detection of hydrogen peroxide, a key player in the redox signaling pathway and a toxic product in the cellular system, using a colorimetric solution assay. Amine-terminated undoped nanocrystalline diamond thin films were grown on glass using a linear-antenna microwave plasma CVD process. The diamond surface consists mainly of -NH(2) termination. The aminated diamond surface was decorated with horseradish peroxidase (HRP) enzyme using carbodiimide coupling chemistry. The success of the HRP immobilization was confirmed by X-ray photoelectron spectroscopy (XPS). The enzymatic activity of immobilized HRP was determined with a colorimetric test based on the HRP-catalyzed oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sufonic acid (ABTS) in the presence of hydrogen peroxide. The surface coverage of active HRP was estimated to be Γ = 7.3 × 10(13) molecules cm(-2). The use of the functionalized diamond surface as an optical sensor for the detection of hydrogen peroxide with a detection limit of 35 nM was demonstrated. 相似文献
68.
M.S. Attia A.O. Youssef Amr A. Essawy M.S.A. Abdel-Mottaleb 《Journal of luminescence》2012,132(10):2741-2746
Highly luminescent complexes of Eu and Tb ions with norfloxacin (NFLX) and gatifloxacin (GFLX) were prepared in sol–gel matrix. The red and green emissions of Eu and Tb ions were obtained by the energy transfer from the triplet state of (NFLX) and (GFLX) to the excited emitting states (5D0 and 5D4) of Eu and Tb, respectively. The intensity of the electric field emission bands (5D0→7F2, 617 nm and 5D4→7F5, 545 nm) of Eu and Tb ions were proportional to the concentration of (NFLX at pH 6.0) and (GFLX at pH 3.5) in acetonitrile with excitation wavelengths (λex) (340 and 395) and (370 and 350 nm) for Eu and Tb ions, respectively. The monitored luminescence intensity of the system showed a good linear relationship with the concentration of NFLX within a range of 5×10?9–5.8×10?6 and 5×10?8–1.0×10?6 mol L?1 with a correlation coefficient of 0.990, and for GFLX within a range of 2.4×10?9–3.2×10?5 and 5×10?8–8.0×10?6 mol L?1 with a correlation coefficient of 0.995. The detection limit (LOD) was determined as 3.0×10?9 and 1.0×10?8 mol L?1 for NFLX and 1.6×10?10 and 2.0×10?8mol L?1 for GFLX. The limit of quantification (LOQ) is 9×10?9 and 3.0×10?8 and 4.8×10?10 and 6.0×10?8 in case of Eu and Tb, respectively. 相似文献
69.
Research on Chemical Intermediates - In this study, a facile and rapid method was developed to synthesize intensely organoselenium compounds, namely ethylseleno[2,3-b]pyridine carboxylate,... 相似文献
70.
Rahal Rabah Amara Korba Abdelaziz Ghoualmi-Zine Nacira 《Wireless Personal Communications》2020,115(2):1415-1444
Wireless Personal Communications - Vehicular ad-hoc networks (VANETs) present security vulnerabilities, which make them prone to diverse cyberattacks. Denial of Service (DoS) is one of the most... 相似文献