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21.
Thanks to advances in the computing capabilities and added functionalities of modern mobile devices, creating and consuming digital media on the move has never been so easy and popular. Most of the DTN routing protocols proposed in the literature to enable content sharing have been exploiting users’ mobility patterns, in order to maximise the delivery probability, while minimising the overall network overhead (e.g., number of message replicas in the system, messages’ path length). Common to all these protocols has been the assumption that devices are willing to participate in the content distribution network; however, because of battery constraints, participation cannot be taken for granted, especially if the very same subset of devices are continuously selected as content carriers, simply because of their mobility properties. Indeed, we demonstrate that state-of-the-art DTN routing protocols distribute load in a highly unfair manner, with detrimental effects on delivery once the assumption of unconditional participation is lifted. To overcome this limitation, we propose a load-balancing mechanism whereby nodes maintain local estimates of network workload, and use them to direct traffic towards the least loaded portion of the network. We implement the mechanism on top of a source-based DTN routing protocol, and demonstrate, by means of simulation using a variety of real mobility traces, that high delivery is now achieved without compromising fairness. 相似文献
22.
Dayu Huang Pingyi Fan Ben Letaief K. 《Wireless Communications, IEEE Transactions on》2008,7(4):1134-1139
This paper addresses the antenna assignment problem for distributed multiple-antenna architecture that enables wireless communication between onboard and ground in subway and railway. We propose a class of algorithms that match the assignment pattern to the large scale fading. Such algorithms are not constrained by short coherence time inherited in subway and railway. We will then derive an optimal antenna assignment strategy employing maximum ratio combining. Simulation results will be provided to demonstrate the advantages of the proposed strategy, which can also be applied to the recently proposed information raining system. 相似文献
23.
In this paper, a new antenna for satellite applications is proposed. This antenna is designed to operate at any frequency desired. It consists of a circular microstrip patch antenna which incorporates concentric annular slits, and it is printed on a grounded substrate. The details of the proposed antenna design and numerical results are presented and discussed. The wave concept iterative procedure in cylindrical coordinates is used to analyze this new antenna. Using the proposed procedure, less computing time and memory are needed to calculate the electromagnetic parameters of the annular multi-slits antenna. 相似文献
24.
O. Godoy-Cabrera R. López-Callejas J. S. Benítez-Read J. O. Pacheco-Sotelo A. de la Piedad-Beneitez 《International Journal of Electronics》2013,100(6):327-340
In this paper, the design and construction of a high-voltage high-frequency serial resonant bridge inverter endowed with a fast resonant frequency following capability, using the digital phase locked loop (DPLL) technique, is described. The main characteristics of this inverter are: high voltage (10?kV), high frequency (94.3?kHz), and low losses in the commutation devices. This inverter is used for the excitation of a dielectric barrier discharge cell (DBDC) for cold plasma generation. The system has been applied in hazardous organic compound degradation. In particular, benzene has been degraded to the order of 99.85%, according to measurements obtained by gas chromatography. 相似文献
25.
本文提出了一种新型的耦合器-全息发光二极管-光纤耦合器,进行了理论设计,给出了设计方法及设计结果。结果表明:这种新型的耦合器可显著增加耦合效率。 相似文献
26.
Martínez Viedma P Sobrino López A Ben Omar N Abriouel H Lucas López R Valdivia E Martín Belloso O Gálvez A 《International journal of food microbiology》2008,128(2):244-249
The effect of the broad spectrum cyclic antimicrobial peptide enterocin AS-48 combination with high-intensity pulsed-electric field (HIPEF) treatment (35 kV/cm, 150 Hz, 4 micros and bipolar mode) was tested on Salmonella enterica CECT 915 in apple juice. A response surface methodology was applied to study the bactericidal effects of the combined treatment. The process variables were AS-48 concentration, temperature, and HIPEF treatment time. While treatment with enterocin AS-48 alone up to 60 microg/ml had no effect on the viability of S. enterica in apple juice, an increased bactericidal activity was observed in combination with HIPEF treatments. Survival fraction was affected by treatment time, enterocin AS48 concentration and treatment temperature. The combination of 100 micros of HIPEF treatment, 30 microg/ml of AS-48, and temperature of 20 degrees C resulted in the lowest inactivation, with only a 1.2-log reduction. The maximum inactivation of 4.5-log cycles was achieved with HIPEF treatment for 1000 micros in combination with 60 microg/ml of AS-48 and a treatment temperature of 40 degrees C. Synergism between enterocin AS-48 and HIPEF treatment depended on the sequence order application, since it was observed only when HIPEF was applied in the presence of previously-added bacteriocin. The combined treatment could improve the safety of freshly-made apple juice against S. enterica transmission. 相似文献
27.
Giuseppa Di Bella Elisabetta Russo Angela Giorgia Potortì Emanuele Saija Hedi Ben Mansour 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2018,35(2):282-291
Farmed European sea bass (Dicentrarchus labrax, Linnaeus, 1758) were collected during 2016 from one Sicilian fish farm that uses two different rearing systems – sea cage and concrete tank – for determination of polychlorinated biphenyls (PCB), organochlorine pesticides (OCP) and polycyclic aromatic hydrocarbons (PAH) residues by HRGC-MS/MS. Moreover, commercial feed was analysed. This study aimed to determine whether the different rearing systems affect the concentration of these compounds, and to assess the safety of cultured fish. PCBs represent the pollutants with the highest concentration; in particular, PCB138 and 153 have the highest concentration in almost all samples. Among OCPs, only 4,4′-DDE, 4,4′-DDD and 4,4′-DDT residues have been detected. Concerning PAHs, only fluorene and phenanthrene were detected, in both rearing systems. Although some residues of organic pollutants were found in the analysed samples, they were always below the MRLs, so the results suggest that farmed sea bass are safe for human consumption. 相似文献
28.
Effects of Extraction Solvents and Provenances on Phenolic Contents and Antioxidant Activities of Cumin (Cuminum cyminum L.) Seeds 总被引:1,自引:0,他引:1
Iness Bettaieb Rebey Soumaya Bourgou Imen Ben Slimen Debez Iness Jabri Karoui Ibtissem Hamrouni Sellami Kamel Msaada Ferid Limam Brahim Marzouk 《Food and Bioprocess Technology》2012,5(7):2827-2836
Polyphenol contents and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity of cumin (Cuminum cyminum L.) seed extracts were compared depending on their geographical origin (Tunisia and India: TCS and ICS, respectively) and the extraction solvent polarity. The ??-carotene bleaching assay, the chelating ability and the reducing power of the most promising solvent extracts were also assessed. In addition, TCS and ICS extracts were acid-hydrolyzed and the phenolics identified by reversed-phase high-performance liquid chromatography (HPLC). Seed phenolic contents and antioxidant activity appeared to be accession and solvent dependent. Extraction with 80% acetone led to the highest polyphenol (18.60 and 16.50?mg gallic acid equivalents (GAE)/g dry weight (DW)), flavonoid (5.91 and 4.99?mg catechin equivalents (CE)/g DW) and tannin (83.23 and 80.23?mg CE/g DW) contents, respectively for TCS and ICS. DPPH scavenging activity, ??-carotene bleaching assay, chelating ability and reducing power were maximal in 80% acetone for both TCS and ICS. HPLC analysis revealed several phenolic compounds in C. cyminum seeds, with p-coumaric (4.83 and 2.33?mg/g DW), trans-2-dihydrocinnamic (1.09 and 1.20?mg/g DW) and rosmarinic (0.70 and 1.04?mg/g DW) acids as major phenolics in TCS and ICS, respectively. Thus, phenolic composition of cumin seeds is also origin dependent. Taken together, our findings indicate that cumin might constitute a rich and novel source of natural antioxidants as food additives in food industry and that acetone 80% would be the most appropriate solvent for seed extraction. 相似文献
29.
This paper illustrates how hidden details in garment design may reveal important clues about the motives of the wearer or designer that are of considerable cultural relevance. We suggest these hidden design features may reflect key psychological factors previously not considered. We illustrate this by doing a multilevel analysis of two important sixteenth century examples of Ottoman court clothing from the Topkapi Palace Museum. We show that these garments contain early examples of the use of “enclothed cognition” where the designs themselves are likely to have influenced the mind of the wearer. We suggest that the historical-social analysis of clothing may benefit from considering the concealed, as well as the explicit, psychologically relevant design features. We suggest that psychosocial interpretations of clothing may help further our understanding of textile and apparel design more generally, even within an historical context. 相似文献
30.
Pilar Martínez Viedma Hikmate Abriouel Angel Sobrino López Nabil Ben Omar Rosario Lucas López Eva Valdivia Olga Martín Belloso Antonio Gálvez 《Food microbiology》2009
Enterocin AS-48 was tested in apple juice against the cider-spoilage, exopolysaccharide-producing strain Lactobacillus diolivorans 29 in combination with high-intensity pulsed-electric field (HIPEF) treatment (35 kV/cm, 150 Hz, 4 μs and bipolar mode). A response surface methodology was applied to study the bactericidal effects of the combined treatment, with AS-48 concentration and HIPEF treatment time as process variables. At subinhibitory bacteriocin concentrations, microbial inactivation by the combined treatment increased as the bacteriocin concentration and the HIPEF treatment time increased (from 0.5 to 2.0 μg/ml and from 100 to 1000 μs, respectively). Highest inactivation (4.87 logs) was achieved by 1000 μs HIPEF treatment in combination with 2.0 μg/ml AS-48. While application of treatments separately did not protect juice from survivors during storage, survivors to the combined treatment were inactivated within the following 24 h of storage, and the treated samples remained free from detectable lactobacilli for at least 15 days at temperatures of 4 °C as well as 22 °C. The combined treatment could be useful for inactivation of exopolysaccharide-producing L. diolivorans in apple juice. 相似文献