In Ambient Assistant Living(AAL) systems, it is a fundamental problem to ensure prompt delivery of detected events, such as irregular heart rate or fall of elderly, to a central processing device(e.g. gateway node). M...In Ambient Assistant Living(AAL) systems, it is a fundamental problem to ensure prompt delivery of detected events, such as irregular heart rate or fall of elderly, to a central processing device(e.g. gateway node). Most of recently proposed MAC protocols for low-power embedded sensing systems(e.g. wireless sensor networks) are designed with energy efficiency as the first goal, so they are not suitable for AAL systems. Although some multi-channel MAC protocols have been proposed to address the problem, most of those protocols ignore the cost of channel switching, which can have reverse effect on network performance, especially latency of data delivery. In this paper, we propose a Delay-Sensitive Multi-channel MAC protocol(DS-MMAC) for AAL systems, which can provide high packet delivery ratio and bound low latency for data delivered to the gateway node. The novelty of the protocol is that an efficient distributed time slot scheduling and channel assignment algorithm is combined with the process of route establishment, which takes the channel switching cost into account and reduces endto-end delay to meet the required delay bound of each data flow. The performance of the proposed protocol is evaluated through extensive simulations. Results show that DS-MMAC can bound low latency for delivering detected events in AAL system to the gateway, while providing high delivery reliability and low energy consumption.展开更多
A new carrier containing three hydrophobic octadecyls was employed to improve the yield and purity of the synthesized oligosaccharides, and the applicability of hydrophobic carrier for HASP （hydrophobically assisted ...A new carrier containing three hydrophobic octadecyls was employed to improve the yield and purity of the synthesized oligosaccharides, and the applicability of hydrophobic carrier for HASP （hydrophobically assisted switching phase） was also explored. High performance liquid chromatography （HPLC） was used to analyze the purity of oligosaccharides and improve the elution efficiency. Elution system was optimized and replaced by isopropyl alcohol and water, in which the excess donor and other impurities had a better solubility than that in methanol.展开更多
基金supported by the International S&T Cooperation Program of China (ISTCP) under Grant No. 2013DFA10690the National Science Foundation of China (NSFC) under Grant No. 61100180
文摘In Ambient Assistant Living(AAL) systems, it is a fundamental problem to ensure prompt delivery of detected events, such as irregular heart rate or fall of elderly, to a central processing device(e.g. gateway node). Most of recently proposed MAC protocols for low-power embedded sensing systems(e.g. wireless sensor networks) are designed with energy efficiency as the first goal, so they are not suitable for AAL systems. Although some multi-channel MAC protocols have been proposed to address the problem, most of those protocols ignore the cost of channel switching, which can have reverse effect on network performance, especially latency of data delivery. In this paper, we propose a Delay-Sensitive Multi-channel MAC protocol(DS-MMAC) for AAL systems, which can provide high packet delivery ratio and bound low latency for data delivered to the gateway node. The novelty of the protocol is that an efficient distributed time slot scheduling and channel assignment algorithm is combined with the process of route establishment, which takes the channel switching cost into account and reduces endto-end delay to meet the required delay bound of each data flow. The performance of the proposed protocol is evaluated through extensive simulations. Results show that DS-MMAC can bound low latency for delivering detected events in AAL system to the gateway, while providing high delivery reliability and low energy consumption.
基金supported by the grants from the National Natural Science Foundation of China(No. 21232002)the National Basic Research Program of China(No. 2012CB822100)
文摘A new carrier containing three hydrophobic octadecyls was employed to improve the yield and purity of the synthesized oligosaccharides, and the applicability of hydrophobic carrier for HASP （hydrophobically assisted switching phase） was also explored. High performance liquid chromatography （HPLC） was used to analyze the purity of oligosaccharides and improve the elution efficiency. Elution system was optimized and replaced by isopropyl alcohol and water, in which the excess donor and other impurities had a better solubility than that in methanol.
