Security is always a hot topic in wireless sensor networks (WSNs). Privacy-preserving data aggregation has emerged as an important concern in designing data aggregation algorithm. This paper proposes a precision-enhanced and encryption-mixed privacy-preserving data aggregation (PEPDA). The objective is to reduce collision during data transmission and energy consumption and to compensate loss caused by the collision. Based on the Slice-Mix-AggRegaTe (SMART) scheme, it optimizes data slicing by using small data packet, node classifying, and positive and negative data slicing techniques. It also describes a randomized time slot and a data compensation algorithm. Theoretical analysis and simulation show that PEPDA demonstrates a good performance in terms of accuracy, complexity, and security.
In recent years, we have seen many applications of secure query in two-tiered wireless sensor networks. Storage nodes are responsible for storing data from nearby sensor nodes and answering queries from Sink. It is critical to protect data security from a compromised storage node. In this paper, the Communication-efficient Secure Range Query (CSRQ)—a privacy and integrity preserving range query protocol—is proposed to prevent attackers from gaining information of both data collected by sensor nodes and queries issued by Sink. To preserve privacy and integrity, in addition to employing the encoding mechanisms, a novel data structure called encrypted constraint chain is proposed, which embeds the information of integrity verification. Sink can use this encrypted constraint chain to verify the query result. The performance evaluation shows that CSRQ has lower communication cost than the current range query protocols.
The heterogeneous hydrogenation of α,β-unsaturated compounds requires understanding of the structure−activity relationship of metallic catalysts in consideration of solvent-mediated processes. In this work, a CoAl hydrotalcites (CoAl-HTs)-supported Pt nanoparticle catalyst is employed to study the effect of solvent water and HTs interlayer water on the aqueous-phase selective hydrogenation of cinnamaldehyde (CALD). Pt/Co 2 Al 1 -HTs catalyst displays 5075 h −1 of specific reaction rate and 89% of CO hydrogenation selectivity at 80 °C under 20 bar of H 2 . Combined results of isotope-labeling experiments and theoretical DFT calculations demonstrate that the water-mediated hydrogen-exchange pathway exists in the reaction with a relatively lower-energy barrier in comparison to the direct H 2 -dissociated hydrogenation pathway. The results also reveal that the interlayer water species of HTs support participate in the hydrogen-exchange reaction. Based on the H 2 −D 2 exchange results, these HTs interlayer water species can promote H 2 activation and dissociation processes and thus accelerate the CALD hydrogenation reaction even under solvent-free conditions.
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