University of Piraeus

About: University of Piraeus is a education organization based out in Piraeus, Attiki, Greece. It is known for research contribution in the topics: Context (language use) & Computer science. The organization has 1731 authors who have published 6209 publications receiving 106699 citations.

The Emergence of Electronic Communications Networks in the U.S. Equity Markets

Abstract: Recent regulatory and technological changes have spurred the development of automated trading systems known as ECNs, or electronic communications networks. Proponents of the networks contend that ECNs can cut transaction costs, accelerate trade execution, and expand the price information available to investors. While some critics have questioned the effects of the ECNs on market integration, it is clear that the networks are poised to play an increasingly important role in the new electronic environment.

Semantic-aware aircraft trajectory prediction using flight plans

Abstract: Aircraft trajectory prediction (TP) is a challenging and inherently data-driven time-series modeling problem Adding annotation or enrichment parameters further increases the search space complexity, especially when ‘blind’ optimization algorithms are employed In this paper, flight plans, localized weather and aircraft properties are introduced as trajectory annotations that enable modeling in a space higher than the typical 4-D spatio-temporal A multi-stage hybrid approach is employed for a new variation of the core TP task, the so-called Future Semantic Trajectory Prediction, including clustering the enriched trajectory data using a semantic-aware similarity function as distance metric Subsequently, a separate predictive model is trained for each cluster, using a nonuniform graph-based grid that is formed by the waypoints of each flight plan In practice, flight plans constitute a constrained-based training of each predictive model, one for each waypoint, independently The proposed method is formulated and experimentally validated with real aviation dataset (flight plans and IFS radar tracks) and localized weather data for a 1-month time frame of flights in the Spanish airspace Various types of predictive models are tested, including hidden Markov model (HMM), linear regressors, regression trees and feed-forward neural networks The results show very narrow confidence intervals for the per-waypoint TP errors in HMM, while the more efficient linear and nonlinear regressors exhibit 3-D spatial accuracy much lower than the current state of the art, up to a factor of five compared to ‘blind’ TP for complete flights, in the order of 2–3 km compared to the actual flight routes

Technology selection from alternatives: a scoring model for screening candidates in equipment purchasing

Abstract: This paper presents a technique to aid decision-making in certain technology selection projects. It describes a scoring model for screening and selecting candidates, suitable for simple cases such as equipment purchase projects. This model considers for each possible alternative its technological performance together with commercial aspects, and analyzes the results on a single "score". The main advantage of the proposed technique is that it is easy to understand and use, while not very time and effort consuming. An example of a real technology selection project from the iron and steel industry is also presented to illustrate the proposed framework.

Wireless World 2020: Radio Interface Challenges and Technology Enablers

Abstract: Future pervasive communication system requirements for two to three orders of magnitude capacity improvement, flexible, fast deployment, and cost/energy efficiency are expected to revolutionize the way we design and use wireless networks. From a network infrastructure perspective, the emphasis is placed on achieving ubiquitous, real-time high data rate communications ?anytime-anywhere,? including at cell-edge, through Small Cell Network architectures and Heterogeneous Cellular Networks (HetNets). From a pervasive systems? perspective, the vision of the Internet of Things suggests the integration between ubiquitous computing and wireless communications targeting a reliable connectivity of things, i.e., computers, sensors, and everyday objects equipped with transceivers. From a backhaul bandwidth, network resource sharing, and optimization perspective, cloud-based processing and radio access network virtualization provide a revolutionary approach toward balancing the degree of centralization of physical and virtual resources management. In this article we analyze these three trends, present key technology enablers, and assess suitable performance merits in an effort to set the scene for the wireless evolution in the era beyond 2020.