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111.
The authors focus on a wireless mesh network, that is, an ad hoc IEEE 802.11-based network whose nodes are either user devices or Access Points providing access to the mesh network or to the Internet. By relying on some work done within the IEEE 802.11s TG, the network nodes can use one control channel and one or more data channels, each on separate frequencies. Then, some problems related to channel access are identified and a MAC scheme is proposed that specifically addresses the problem of hidden terminals and the problem of coexisting control and data traffic on different frequency channels. An analytical model of the MAC scheme is presented and validated by using the Omnet++ simulator. Through the developed model, we show that our solution achieves very good performance both in regular and in very fragmented mesh topologies, and it significantly outperforms the standard 802.11 solution. 相似文献
112.
Olivier Malek Jef Vleugels Yeczain Perez Patrick De Baets Junhu Liu Sven Van den Berghe Bert Lauwers 《Materials Chemistry and Physics》2010
The interrelationships between the dispersion of the ZrO2 phase and the electrical discharge machining (EDM) behaviour of WC based composites with 0, 5 or 10 vol% of ZrO2 are investigated. Special attention was given to the homogeneity of the ultrafine WC – nanometric ZrO2 powder based composites which were fully densified by means of pulsed electric current sintering (PECS). X-ray photoelectron spectroscopy (XPS) measurements revealed the presence of a nanometric WO3 layer on the EDM surface, confirming oxidation as the major material removal mechanism (MRM). The surface roughness after the final EDM finishing regime was strongly influenced by the composite homogeneity and could be reduced down to 0.15 μm (Ra) on agglomerate-free composites. Residual stress measurements indicated that EDM did not introduce a significant amount of surface stresses, especially not after the final finishing regime. XRD measurements of EDM surfaces however indicated surface depletion of ZrO2 by the formation of ZrC and W2C during spark erosion. 相似文献
113.
The synthesized zeolite NaY from rice husk ash (RHA) and the commercial zeolite NaY both modified with surfactants in amounts equal to 50%, 100% and 200% of their external cation exchange capacity (ECEC) were used to remove chromate and arsenate anions from aqueous solutions. While the unmodified zeolite Y had little or no affinity for the Cr(VI) and As(V) anionic species, the surfactant-modified zeolite Y (SMZY) showed significant ability to remove of these anions from the aqueous solutions. The highest chromates and arsenates adsorption efficiency was observed from solutions of pH values 3 and 8, respectively because of the dominance of the univalent species of both anions. The adsorption equilibrium data were best fitted with the Langmuir isotherm model with the highest removal capacities observed for the SMZY initially prepared considering the hexadecyltrimethyl ammonium (HDTMA) amount equal to the 100% of the ECEC of zeolite Y. Synthesized SMZY remove Cr(VI) and As(V) more than the corresponding commercial one due to its lower silica to alumina ratio. Thus, the HDTMA-covered modified zeolite Y synthesized using RHA can be used to remove Cr(VI) and As(V) from water. 相似文献
114.
Ryan Fitzgerald Andrew Olsen Jessica Nguyen Winifred Wong Malek El Muayed Joshua Edwards 《International journal of molecular sciences》2021,22(1)
Cadmium (Cd) is an anthropogenic as well as a naturally occurring toxicant associated with prediabetes and T2DM in humans and experimental models of Cd exposure. However, relatively few studies have examined the mechanism(s) of Cd-induced hyperglycemia. The purpose of this study was to examine the role of pancreatic islets in Cd-induced hyperglycemia. Male Sprague–Dawley rats were given daily subcutaneous doses of Cd at 0.6 mg/kg over 12 weeks. There was a resulting time-dependent increase in fasting blood glucose and altered insulin release in vitro. Islets isolated from control (saline-treated) and Cd-treated animals were incubated in low (0.5 mg/mL) or high (3 mg/mL) glucose conditions. Islets from 12 week Cd-treated animals had significantly less glucose-stimulated insulin release compared to islets from saline-treated control animals. The actual Cd content of isolated islets was 5 fold higher than the whole pancreas (endocrine + exocrine) and roughly 70% of that present in the renal cortex. Interestingly, islets isolated from Cd-treated animals and incubated in high glucose conditions contained significantly less Cd and zinc than those incubated in low glucose. These results show that within whole pancreatic tissue, Cd selectively accumulates in pancreatic islets and causes altered islet function that likely contributes to dysglycemia. 相似文献
115.
Silicon - In this paper a novel structure is proposed for silicon on insulator MOSFETs which improves DC and RF characteristics by three vertical layers of 4H-SiC. Vertical layers are in parallel... 相似文献
116.
Frontiers of Information Technology & Electronic Engineering - Unfortunately the second author’s name has been misspelt. It should be read: Abbas NIKNAFS. 相似文献
117.
Abraham Shaun Al-Khatib Obada Abdul Malek Mohamed Fareq 《Telecommunication Systems》2020,73(1):131-142
Telecommunication Systems - The latest mobile applications, such as GPS, games, virus scanning, and face detection and recognition, are compute-intensive applications consuming a lot of energy when... 相似文献
118.
Chronic hepatitis caused by the hepatitis C virus (HCV) is a common condition that leads to cirrhosis and hepatocellular carcinoma. Current treatment with interferon is unsatisfactory, with a low percentage of patients who respond and uncertain high-term significance; in addition, it is associated with sometimes severe side effects. The increasing sophistication of molecular biology has enabled viral characteristics such as viral load, genotypes, and quasi-species to be identified, which may help predict a patient's response to interferon treatment. We suggest that interferon therapy for hepatitis C virus should be restricted to referral centers in the context of controlled trials. 相似文献
119.
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