Nikos Tziritas

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In a cloud computing paradigm, energy efficient allocation of different virtualized ICT resources (servers, storage disks, and networks, and the like) is a complex problem due to the presence of heterogeneous application (e.g., content delivery networks, MapReduce, web applications, and the like) workloads having contentious allocation requirements in terms(More)
In this survey, we review different text mining techniques to discover various textual patterns from the social networking sites. Social network applications create opportunities to establish interaction among people leading to mutual learning and sharing of valuable knowledge, such as chat, comments, and discussion boards. Data in social networking(More)
Grid is a distributed high performance computing paradigm that offers various types of resources (like computing, storage, communication) to resource-intensive user tasks. These tasks are scheduled to allocate available Grid resources efficiently to achieve high system throughput and to satisfy user requirements. The task scheduling problem has become more(More)
In this paper we tackle the problem of virtual machine (VM) placement onto physical servers to jointly optimize two objective functions. The first objective is to minimize the total energy spent within a cloud due to the servers that are commissioned to satisfy the computational demands of VMs. The second objective is to minimize the total network overhead(More)
Recent embedded middleware initiatives enable the structuring of an application as a set of collaborating agents deployed in the various sensing/actuating entities of the system. Of particular importance is the incurred cost due to agent communication which in terms depends on agent positions in the system. In this paper we present GRAL a grouping algorithm(More)
Given two replication schemes X<sup>old</sup> and X<sup>new</sup>, the replica transfer scheduling problem (RTSP) aims at reaching X<sup>new</sup>, starting from X<sup>old</sup>, with minimal implementation cost. In this paper we generalize the problem description to include special cases, where deadlocks can occur while in the process of implementing(More)
Embedded applications can be structured in terms of mobile agents that are flexibly installed on available nodes. In wireless systems, such nodes typically have limited battery and memory resources; therefore it is important to place agents judiciously. In this paper we tackle the problem of placing a newcomer agent in such a system. The problem has two(More)
This paper describes middleware-level support for agent mobility, targeted at hierarchically structured wireless sensor and actuator network applications. Agent mobility enables a dynamic deployment and adaptation of the application on top of the wireless network at runtime, while allowing the middleware to optimize the placement of agents, e.g., to reduce(More)
In the large-scale parallel computing environment, resource allocation and energy efficient techniques are required to deliver the quality of services (QoS) and to reduce the operational cost of the system. Because the cost of the energy consumption in the environment is a dominant part of the owner’s and user’s budget. However, when considering energy(More)