The implementation of IP technology in wireless sensor networks has promoted the development of many smart scenarios. To enhance secure access in IP-enabled wireless sensor networks, access control to sensor nodes is a necessary process. However, access control currently faces two challenges, feasibility and preservation of user access privacy. In this paper, we propose eHAPAC, a novel privacy-preserving access control model for IP-enabled wireless sensor networks. The contributions of our paper include three parts. First, this paper integrates the Hidra access control protocol and APAC privacy-preserving model, addressing the issue of privacy-preserving access control in resource-constrained devices. Second, this paper proposes an enhanced Hidra protocol to implement the unlinkability of protocol message exchanges. Third, to solve the problem of third party credibility, this paper improves the group signature-based APAC model and utilizes blockchain technology to manage the storage and publication of public group signature keys. Security analysis and performance evaluation prove that our protocol is secure and effective.

Incomplete preferences of agents may render service selection ineffective. We address this problem by proposing a set of collaborative approaches to complementing agents' incomplete preferences in a qualitative way. For an agent, the approaches first find its similar agents, and then base the similar agents' qualitative preferences to complement this agent's missing preferences. We analyze and compare these approaches and provide experimental results to justify our arguments. We also compare our approach with the classic collaborative filtering and show the competitive advantages of our approach in service selection. Our work thus serves as an important step towards effective service selection.

Here, we obtained the whole-genomes of six H5N1 viruses from dead or rescued wild birds in Hubei Province. These viruses were divided into two genotypes and had different evolutionary trajectories from previously reported H5N1 viruses in China.