1,244 research outputs found

    Regional Specialization of Greek Prefectures for the Time Period 1981-2001

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    Intense regional inequalities are considered to be widespread in Greece. Indeed, Athens mainly, and Thessaloniki consist the two poles in Greece, Thessaloniki in a lower degree though. In these two cities the larger part of industrial activity, as well as, tertiary sector activities, is assembled. On the contrary, in the other Greek regions not only the economic activities but also the infrastructures have been developed in smaller degree. Moreover, as it is well known, two Greek regions (Northern Aegean, Epirus) are among the poorest in the European Union. This fact constitutes a reluctant factor to the effort of Greece to increase the standard of living of the citizens. In addition, the last two decades, a significant decrease of the contribution of primary sector to the GDP with simultaneous increase of the contribution of the tertiary sector is observed. The particular change involves significant repercussions to the national economy. The aim of this paper is the study of the specialization of Greek prefectures as well as spatial distribution of 13 sectors of economic activity using employment data and methods of regional analysis such as Gini – Hirschman coefficient, Location Quotient Coefficient (LQ), Coefficient of Location (CL), Coefficient of Specialization (CS) and analysis of variation – participation.

    Large scale musical instrument identification

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    In this paper, automatic musical instrument identification using a variety of classifiers is addressed. Experiments are performed on a large set of recordings that stem from 20 instrument classes. Several features from general audio data classification applications as well as MPEG-7 descriptors are measured for 1000 recordings. Branch-and-bound feature selection is applied in order to select the most discriminating features for instrument classification. The first classifier is based on non-negative matrix factorization (NMF) techniques, where training is performed for each audio class individually. A novel NMF testing method is proposed, where each recording is projected onto several training matrices, which have been Gram-Schmidt orthogonalized. Several NMF variants are utilized besides the standard NMF method, such as the local NMF and the sparse NMF. In addition, 3-layered multilayer perceptrons, normalized Gaussian radial basis function networks, and support vector machines employing a polynomial kernel have also been tested as classifiers. The classification accuracy is high, ranging between 88.7% to 95.3%, outperforming the state-of-the-art techniques tested in the aforementioned experiment

    Pauesia silana Tremblay, 1969 a parasitoid of Cinara-aphids on Conifers in Malta (Hymenoptera: Braconidae: Aphidiinae)

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    Pauesia silana is recorded for the first time from Malta and the Lefkada and Meganissi islands in Greece. From Malta, the species was reared from Cinara palaestinensis on Pinus halepensis from material collected from Buskett. From the Greek islands, the species was collected on Cinara sp. on the same mentioned hostplant. The new record contributes to the information on its distribution, hosts and plant associations in the Mediterranean area.peer-reviewe

    Centrifuge modeling of rocking-isolated inelastic RC bridge piers

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    Experimental proof is provided of an unconventional seismic design concept, which is based on deliberately underdesigning shallow foundations to promote intense rocking oscillations and thereby to dramatically improve the seismic resilience of structures. Termed rocking isolation, this new seismic design philosophy is investigated through a series of dynamic centrifuge experiments on properly scaled models of a modern reinforced concrete (RC) bridge pier. The experimental method reproduces the nonlinear and inelastic response of both the soil-footing interface and the structure. To this end, a novel scale model RC (1:50 scale) that simulates reasonably well the elastic response and the failure of prototype RC elements is utilized, along with realistic representation of the soil behavior in a geotechnical centrifuge. A variety of seismic ground motions are considered as excitations. They result in consistent demonstrably beneficial performance of the rocking-isolated pier in comparison with the one designed conventionally. Seismic demand is reduced in terms of both inertial load and deck drift. Furthermore, foundation uplifting has a self-centering potential, whereas soil yielding is shown to provide a particularly effective energy dissipation mechanism, exhibiting significant resistance to cumulative damage. Thanks to such mechanisms, the rocking pier survived, with no signs of structural distress, a deleterious sequence of seismic motions that caused collapse of the conventionally designed pier. © 2014 The Authors Earthquake Engineering & Structural Dynamics Published by John Wiley & Sons Ltd

    Sedimentological, geomorphological and geochronological studies on Holocene tsunamis in the Lefkada / Preveza area (NW Greece) and their implications for coastal evolution

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    Research on palaeo-tsunami and palaeo-extreme wave events aims to provide new data about former events and is of remarkable importance in the eastern Mediterranean. In general, coastal geomorphology and fine-grained near-coast geological archives store information about coastal changes over medium to long timescales, as well as short, episodic processes such as palaeo-tsunami events. In the eastern Mediterranean and particularly for the Ionian Sea and the Lefkada / Preveza coastal zone (NW Greece), strong seismic activity and a high tsunamigenic potential are evident. Thus, comprehensive geo-scientific investigations were carried out in the Lefkada / Preveza coastal zone in order to decipher coastal change throughout time, and thereby detect, verify and date the influence of tsunami events on the coastal system and coastal evolution. Herein, particular focus was set on the distinguishability of event deposits in the geological record and the evaluation of event recurrence rates - an issue of major importance in extreme wave event research. In a first step, detailed analysis of the geomorphological and geomorphodynamic situation in the study area revealed several major disturbances of the coastal system, which mark episodically occurring major impulses of coastal evolution, entailing the recurrent reorganization of coastal balance. In a second step, comprehensive geo-scientific investigations on the main near-coast geological archives provided insight into the palaeogeographical evolution and the palaeo-event history of the Lefkada / Preveza area. In the sedimentary record of the Phoukias sand spit and the washover-dominated northern Lefkada Lagoon, distinct event deposits were identified. These event deposits provide a linkage to the inferred disturbances of the coastal system and allow the dating of the main impulses in coastal evolution. Detailed analyses of the event deposits - comprising sedimentological, microfaunal and geochemical investigations as well as the interpretation of the regional geomorphologic and geographic context - strongly suggest a tsunamigenic origin of the encountered event deposits, proving the significant impact of tsunamis on the coastal system. Moreover, numerous block and boulder fields were mapped along the coastline and equally point to the impact of high energy wave events. Altogether, four major tsunamigenic disturbances were identified throughout the late Holocene. These disturbances were dated to ~1000 BC, to at around or after 300 BC and, for the main washover structures in the northern Lagoon of Lefkada, to at around or after 300 AD, the latter event most likely triggered by the 365 AD earthquake off western Crete and the related tsunami. During the younger history of coastal evolution a fourth disturbance occurred sometime before 1850 AD. In addition to the detected 365 AD event, the presented findings fit well to previous investigations in adjacent coastal zones. From a geomorphological and geomorphodynamic point of view, the major tsunami events involved the breakdown of former coastlines (the Plaka), the formation of the Phoukias sand spit and the onset of intense coastal erosion in western Aktium Headland. Moreover, the inferred tsunami events contributed to the formation of block and boulder fields, induced the evolution of ridge structures in the northern part of the Phoukias sand spit and triggered the formation of at least one, probably two washover generations in the northern Lefkada Lagoon. The episodic occurrence of tsunami events was thus responsible for the formation of major geomorphological structures and modifications of the coastal system, which are recurrently masked and mimicked by long term, gradually operating coastal processes. These marked geomorphic changes provide clear evidence that tsunami-induced disturbances exert a major control on the evolution of the coastal system in the study area. In conclusion, this study presents new geo-scientific evidence of extreme wave event deposits and will thereby expand the regional and global data pool of palaeo-event and particularly palaeo-tsunami deposits. Moreover, it contributes to ongoing research concerned with the detection of extreme wave event deposits in near-coast geological archives, ultimately enabling an improved understanding of type and degree of their impact on the evolution of coastal systems