The airport gate assignment problem (AGAP) is one of the most important problems operations managers face daily. Many researches have been done to solve this problem and tackle its complexity. The objective of the task is assigning each flight (aircraft) to an available gate while maximizing both conveniences to passengers and the operational efficiency of airport. This objective requires a solution that provides the ability to change and update the gate assignment data on a real time basis. In this paper, we survey the state of the art of these problems and the various methods to obtain the solution. Our survey covers both theoretical and real AGAP with the description of mathematical formulations and resolution methods such as exact algorithms, heuristic algorithms, and metaheuristic algorithms. We also provide a research trend that can inspire researchers about new problems in this area.

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Multi-Agent Systems (MAS) have been widely used in many areas like modeling and simulation of complex phenomena, and distributed problem solving. Likewise, MAS have been used in cyber-security, to build more efficient Intrusion Detection Systems (IDS), namely Collaborative Intrusion Detection Systems (CIDS). This work presents a taxonomy for classifying the methods used to design intrusion detection systems, and how such methods were used alongside with MAS in order to build IDS that are deployed in distributed environments, resulting in the emergence of CIDS. The proposed taxonomy, consists of three parts: 1) general architecture of CIDS, 2) the used agent technology, and 3) decision techniques, in which used technologies are presented. The proposed taxonomy reviews and classifies the most relevant works in this topic and highlights open research issues in view of recent and emerging threats. Thus, this work provides a good insight regarding past, current, and future solutions for CIDS, and helps both researchers and professionals design more effective solutions.

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We investigate three aspects of dynamicity in ad hoc and wireless sensor networks and their impact on the efficiency of intrusion detection systems (IDSs). The first aspect is magnitude dynamicity, in which the IDS has to efficiently determine whether the changes occurring in the network are due to malicious behaviors or or due to normal changing of user requirements. The second aspect is nature dynamicity that occurs when a malicious node is continuously switching its behavior between normal and anomalous to cause maximum network disruption without being detected by the IDS. The third aspect, named spatiotemporal dynamicity, happens when a malicious node moves out of the IDS range before the latter can make an observation about its behavior. The first aspect is solved by defining a normal profile based on the invariants derived from the normal node behavior. The second aspect is handled by proposing an adaptive reputation fading strategy that allows fast redemption and fast capture of malicious node. The third aspect is solved by estimating the link duration between two nodes in dynamic network topology, which allows choosing the appropriate monitoring period. We provide analytical studies and simulation experiments to demonstrate the efficiency of the proposed solutions.