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Yayın Modeling and simulation support to the defense planning process(Sage Publications Inc, 2017-04-01) Çayırcı, Erdal; Özçakır, LütfüDefense planning is a crucial part of the defense process. It identifies the capabilities required for the future defense environment, analyzes the capability shortfalls, prioritizes them, and provides the fundamental inputs for their development. Modeling and simulation may significantly contribute to the success of defense planning. However, neither the theory nor the tools are mature enough to fulfill the defense planning requirements. Various types of simulation tools, such as static, dynamic, deterministic, stochastic, closed, discrete, continuous, and symbiotic, in multiple levels of resolution and fidelity are needed to support the different stages and phases. The verification and validation of the models and the analysis of the input and output data are critical. Yet another challenge is that the uncertainties related to the contemporary defense scenarios are mostly not in aleatory but in the epistemic domain. In this paper, we briefly present a new computer-assisted defense planning process. Then, we introduce the service-oriented cloud approach for the modeling and simulation support to the process.Yayın Querying sensor networks by using dynamic task sets(Elsevier B.V., 2006-05-15) Çayırcı, Erdal; Coşkun, Vedat; Çimen, ÇağhanA data querying scheme is introduced for sensor networks where queries formed for each sensing task are sent to task sets. The sensor field is partitioned into subregions by using quadtree based addressing, and then a given number of sensors from each subregion are assigned to each task set by using a distributed algorithm. The number of nodes in a task set depends on the task specifications. Hence, the sensed data is retrieved from a sensor network in the level of detail specified by users, and a tradeoff mechanism between data resolution and query cost is provided. Experiments show that the dynamic task sets scheme systematically reduces the number of sensors involved in a query in the orders of magnitude in the expense of slight reduction in the event detection rate.Yayın Quarantine region scheme to mitigate spam attacks in wireless sensor networks(IEEE, 2006-08) Coşkun, Vedat; Çayırcı, Erdal; Levi, Albert; Sancak, SerdarThe Quarantine Region Scheme (QRS) is introduced to defend against spam attacks in wireless sensor networks where malicious antinodes frequently generate dummy spam messages to be relayed toward the sink. The aim of the attacker is the exhaustion of the sensor node batteries and the extra delay caused by processing the spam messages. Network-wide message authentication may solve this problem with a cost of cryptographic operations to be performed over all messages. QRS is designed to reduce this cost by applying authentication only whenever and wherever necessary. In QRS, the nodes that detect a nearby spam attack assume themselves to be in a quarantine region. This detection is performed by intermittent authentication checks. Once quarantined, a node continuously applies authentication measures until the spam attack ceases. In the QRS scheme, there is a trade-off between the resilience against spam attacks and the number of authentications. Our experiments show that, in the worst-case scenario that we considered, a not quarantined node catches 80 percent of the spam messages by authenticating only 50 percent of all messages that it processes.Yayın A model to describe hybrid conflict environments(Dime University of Genoa, 2016) Çayırcı, Erdal; Bruzzone, Agostino G.; Longo, Franceso; Gunneriusson, HakanThis article focuses on the definition, implementation and testing of a model to describe Hybrid Conflict Environments. Without the need of citing specific cases or countries, it is clear that hybrid strategy and warfare are becoming more important. A hybrid strategy can affect policy makers, military operations, economics and financial trends, intelligence and legal activities as well as information and media. A conceptual model is introduced to define and to gain further insight into hybrid environments. The model is then implemented and tested by running experiments to provide evidence on its relevance. Finally, results are presented and discussed.
