Sharif Digital Repository

Data aggregation is a key, yet time-consuming functionality introduced to conserve energy in wireless sensor networks (WSNs). In this paper, to minimize time latency, we focus on aggregation scheduling problem and propose an efficient distributed algorithm that generates a collision-free schedule with the least number of time slots. In contrast to others, our approach named FAST mainly contributes to both tree construction, where the former studies employ Connected 2-hop Dominating Sets, and aggregation scheduling that was previously addressed through the Competitor Sets computation. We prove that the latency of FAST under the protocol interference model is upper-bounded by 12R+Δ-2, where R... 

The surface area which is defined as the number of vertices at a given distance from a base vertex of a graph is considered to be as one of the most useful yet abstract combinatorial properties of a graph. The applicability of surface area spans many problem spaces such as those in parallel and distributed computing. These problems normally involve combinatorial analysis of underlying graph structures (e.g., spanning tree construction, minimum broadcast algorithms, efficient VLSI layout, performance modeling). In this paper, we focus on the problem of finding the surface area of a class of popular graphs, namely the family of WK-recursive and swapped networks. These are attractive networks... 

This study presents a passive model to detect islanding conditions of synchronous distributed generation resources in a distribution network or a microgrid. The proposed approach uses the classification and regression tree algorithm for distinguishing between islanding and non-islanding situations. It utilises the rate of change of frequency (ROCOF) and harmonic content of the equivalent reactance seen at the location of distributed generation as input features for decision tree construction. Indeed the thresholds of the proposed input features are extracted by the decision tree algorithm. The output if-then rules of the decision tree algorithm are then utilised to make a new relay logic for...