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In Mobile Social Networks (MSNs), people contact each other through mobile devices, such as smartphones and tablets, while they move freely. The communication takes place on-the-fly by the opportunistic contacts between mobile users via local wireless bandwidth, such as Bluetooth or WiFi without a network infrastructure. Social Multicast is an important routing service in MSNs where data transmission is addressed to a group of users according to their social features. The aim of this paper is to find and recommend mobile nodes that can efficiently relay and consume messages based on their social features. Efficiency in this context is to achieve high delivery ratio while reducing considering resources constraints and limitations such as power and space. The proposed algorithm, TESS, measures social similarity based on Time-based Encounter of Socially Similar nodes. We compare the proposed algorithm with the known social multicast algorithms: Multi-CSDO, EncoCent and Epidemic. Simulations results show that the proposed algorithm outperforms others in terms of delivery ratio and network overhead.

Connecting mobile computing devices, such as smartphones and tablets, anytime and anywhere has been the target of mobile networks in recent decades. Nowadays, this concept is extended to connecting selected people, which requires knowing the social profile of the device users, and therefore created the Mobile Social Network (MSN).Multicast routing in MSNs is concerned with finding and selecting people to deliver a message. Traditional multicast routing protocols do not consider the users’ profile. Recently, some social multicast protocols have emerged. These protocols consider the social behavior and relationships of the users to decide which nodes can act as relays and which ones can be considered destinations.The aim of this paper is to experimentally compare and analyze the performance of three known protocols in MSNs. The performance measures used are: delivery ratio, relay count, overhead ratio, hop count and dropped packets. The experiments are run with different network sizes, variable buffer capacities and packets Time-To-Live (TTL). The paper is concluded with a summarized analysis of the compared protocols.

This paper is aimed at calculating the onset voltage of a sliding discharge established between two electrodes at the upper and bottom surfaces of a dielectric barrier plate; named sliding dielectric barrier discharge (SDBD) driven by AC voltage during negative half cycle. The onset voltage is based on the condition of self-sustenance of avalanche growth in the vicinity of the stressed electrode. This calls at first for calculation of the electric field in the vicinity of stressed electrode. The dependency of onset voltage on the thickness and permittivity of the dielectric barrier as well as the thickness of the stressed electrode and the inter-electrode spacing between the stressed and ground electrodes is investigated. The obtained results are discussed in the light of gas discharge physics.