Showing papers by "University of the Aegean published in 2006"
TL;DR: A review in the related literature presented in this paper reveals that better performance has been reported, when limitations in distance, angle of view, illumination conditions are set, and background complexity is low.
Abstract: In this paper, a new algorithm for vehicle license plate identification is proposed, on the basis of a novel adaptive image segmentation technique (sliding concentric windows) and connected component analysis in conjunction with a character recognition neural network. The algorithm was tested with 1334 natural-scene gray-level vehicle images of different backgrounds and ambient illumination. The camera focused in the plate, while the angle of view and the distance from the vehicle varied according to the experimental setup. The license plates properly segmented were 1287 over 1334 input images (96.5%). The optical character recognition system is a two-layer probabilistic neural network (PNN) with topology 108-180-36, whose performance for entire plate recognition reached 89.1%. The PNN is trained to identify alphanumeric characters from car license plates based on data obtained from algorithmic image processing. Combining the above two rates, the overall rate of success for the license-plate-recognition algorithm is 86.0%. A review in the related literature presented in this paper reveals that better performance (90% up to 95%) has been reported, when limitations in distance, angle of view, illumination conditions are set, and background complexity is low
740 citations
TL;DR: In this article, the authors examined the relationship between transformational leadership and organizational cultural orientations, as well as the joint effect of Transformational Leadership and organizational culture on business unit performance.
Abstract: Purpose – The aim of the study was to examine the relationship between transformational leadership and organizational cultural orientations, as well as the joint effect of transformational leadership and organizational culture on business unit performance.Design/methodology/approach – About 300 employees of a large financial organization in Greece filled in a number of questionnaires measuring organizational culture orientations and transformational leadership. The measurement of business unit performance was obtained by the organization under study.Findings – A path analysis showed that the achievement and adaptive cultural orientations had a direct effect on performance. Moreover, transformational leadership and humanistic orientation had an indirect positive impact on performance via achievement orientation.Research limitations/implications – A research limitation is that the causal direction of the relations between the predictors and the criteria has been partially established by controlling for the ...
337 citations
TL;DR: It is found that the three plant invaders had an impact on plant community structure not entirely concordant with changes in soil properties, suggesting that impact of invaders is context-specific.
Abstract: Aims Although biological invasions occur throughout the world, and some invaders are widespread in many habitats, few studies on the ecological impact of invaders have examined multiple sites. We tested how the impact of three widespread plant invaders changed depending on the identity of the species and the invaded island. We also tested whether relative species loss was lower in species-rich communities than in species-poor ones.
Location We conducted floristic surveys and soil analyses in eight Mediterranean Basin islands: Crete and Lesbos (Greece), Sardinia (Italy), Corsica, Bagaud and Porquerolles (France), and Mallorca and Menorca (Spain).
Methods We compared native species richness and diversity, proportion of life forms, soil percentage nitrogen, percentage organic carbon, C/N, and soil pH in nearby paired plots of 2 × 2 m: one control and one invaded by either the deciduous tree Ailanthus altissima, the succulent subshrubs Carpobrotus spp. or the annual geophyte Oxalis pes-caprae, across eight Mediterranean Basin islands.
Results On average, the presence of invaders reduced species diversity, Carpobrotus spp. exhibiting the largest impact and Oxalis the least. However, the relative impact was island-dependent, and was positively but weakly associated with the species richness of the recipient community. Therophytes were the life form that experienced the largest decrease across islands. The effects of invasion on soil properties were very variable. Total N changed (increased) only in plots invaded by Ailanthus, significantly decreasing the C/N ratio. The presence of this tree increased soil pH, whereas the opposite was found in plots invaded by the other two species. Organic C increased in plots invaded by Ailanthus and Carpobrotus species.
Main conclusions By conducting an analysis at multiple sites, we found that the three plant invaders had an impact on plant community structure not entirely concordant with changes in soil properties. The impacts depended on the identity of the species and of the invaded island, suggesting that impact of invaders is context-specific. The impact in terms of species loss was not lower in species-rich than in species-poor communities.
267 citations
TL;DR: In this article, a methodological framework is developed to provide insights regarding the suitability of multi-criteria techniques in the context of renewable energy planning, and a comparative matrix is created with the various appropriate multicriteria techniques and their performance.
Abstract: This article develops a methodological framework to provide insights regarding the suitability of multi-criteria techniques in the context of renewable energy planning. The second section presents main characteristics of the particular decision-making process. The third section presents the main multi-criteria analysis methods, and the fourth section reveals the requirements of the techniques for renewable energy planning and the main attributes under which these methods should be evaluated. Subsequently, in the fifth section, a comparative matrix is created with the various appropriate multi-criteria techniques and their performance. Finally in the sixth sec tion, we present our conclusions.
244 citations
12 Sep 2006
TL;DR: The authors proposed a variable-length n-gram approach inspired by previous work for selecting variable length word sequences for authorship identification, using a subset of the new Reuters corpus, consisting of texts on the same topic by 50 different authors.
Abstract: Automatic authorship identification offers a valuable tool for supporting crime investigation and security. It can be seen as a multi-class, single-label text categorization task. Character n-grams are a very successful approach to represent text for stylistic purposes since they are able to capture nuances in lexical, syntactical, and structural level. So far, character n-grams of fixed length have been used for authorship identification. In this paper, we propose a variable-length n-gram approach inspired by previous work for selecting variable-length word sequences. Using a subset of the new Reuters corpus, consisting of texts on the same topic by 50 different authors, we show that the proposed approach is at least as effective as information gain for selecting the most significant n-grams although the feature sets produced by the two methods have few common members. Moreover, we explore the significance of digits for distinguishing between authors showing that an increase in performance can be achieved using simple text pre-processing.
210 citations
TL;DR: The HCOME methodology aims to empower knowledge workers to continuously manage their formal conceptualizations in their day-to-day activities and shape their information space by being actively involved in the ontology life cycle.
Abstract: The fast emergent and continuously evolving areas of the Semantic Web and Knowledge Management make the incorporation of ontology engineering tasks in knowledge-empowered organizations and in the World Wide Web more than necessary. In such environments, the development and evolution of ontologies must be seen as a dynamic process that has to be supported through the entire ontology life cycle, resulting to living ontologies. The aim of this paper is to present the Human-Centered Ontology Engineering Methodology (HCOME) for the development and evaluation of living ontologies in the context of communities of knowledge workers. The methodology aims to empower knowledge workers to continuously manage their formal conceptualizations in their day-to-day activities and shape their information space by being actively involved in the ontology life cycle. The paper also demonstrates the Human Centered ONtology Engineering Environment, HCONE, which can effectively support this methodology.
205 citations
TL;DR: It is concluded that the three habitats of greatest overall value for plant-pollinator communities and provision of the healthiest pollination services are pine forests, oak woodland and managed olive groves.
198 citations
TL;DR: In this paper, the consequences for agricultural land use, combining models of crop growth and farm decision making to predict profitability over the whole of Europe, driven solely by soil and climate at each location.
191 citations
TL;DR: In this paper, the authors measured air temperature, relative humidity and solar radiation in the sun and shade of the trees in urban parks in Thessaloniki, Greece, to assess the correlation between parameters that affect the microclimate of parks during the summer.
Abstract: Trees in cities have an important positive effect on people’s lives. One such positive effect is the amelioration of microclimate. The aim of this research is to assess the correlation between parameters that affect the microclimate of parks during the summer. We measured air temperature, relative humidity and solar radiation in the sun and shade of the trees in urban parks in Thessaloniki, Greece. The results indicate that: the air (A) temperature reduction percentage (dTair%), air relative humidity increase (dTRh%), discontent index reduction percentage (DI%) (cooling effect) and solar radiation (L) percentage that passes through the trees’ foliage to their shade creates an exponential function of dA% = a.e-bL. These functions are also applicable to the limiting variation values of the parameters. If we use L = 0 (meaning Lightsh = 0, which is the case for an extremely dense tree), then the values that we expect from this particular parameter are the maximum possible. These maximum values are a characteristic feature of the parameter variation for this particular research area. These maximum values for the trees in the parks of Thessaloniki are: maxdTair% ≈ 24%, maxdRh% ≈ 41% and maxdDI% ≈16%.
178 citations
TL;DR: Although measured levels of the downward flux of suspended particulate matter and suspended solids were well within "normal" levels recorded in the literature, it was the proportion of benthic space, generic coral composition, and site history that offered compelling evidence of chronic exposure to increased sediment load.
154 citations
TL;DR: In this article, taxonomic-free descriptors are proposed to provide relevant information for each of the four main biotic compartments in coastal lagoons, including fish, benthos and macrophyte.
Abstract: 1.
Transitional waters, described as critical transition zones because of their position at terrestrial, freshwater and marine interfaces, provide essential goods and services to the biosphere including human populations. These ecotones face increasing human influence mainly due to population density increase in coastal areas.
2.
Transitional water bodies have, to date, received little attention in the development of ecological status indicators; this is a critical deficiency when trying to meet the Water Framework Directive objective of all significant water bodies achieving good ecological status by the year 2015.
3.
In order to assess changes in transitional water communities many taxonomic-based indicators have already been proposed but there are a number of concerns for their use such as taxonomic classification difficulties, their unsuitability for multi-site comparisons and their inconsistent relationships with disturbance or stress.
4.
Alternative methods based on body size, abundance distribution among functional groups, functional diversity and productivity descriptors are proposed. These methods offer the opportunity to compare sites with different taxonomic compositions and allow derivation of indicators related to ecological status of communities under scrutiny.
5.
Finally, the suitability of these taxonomic-free descriptors to provide relevant information for each of the four main biotic compartments in coastal lagoons is discussed. The use of biomass distribution among functional groups for fish, benthos and macrophyte and to use body-size distribution for benthos and plankton is proposed.
Copyright © 2006 John Wiley & Sons, Ltd.
TL;DR: The most recent major explosive eruption of the Santorini volcano in Greece, referred to as the Minoan eruption, is one of the largest volcanic events known in historical time and has been the subject of intense volcanological and archeological studies as discussed by the authors.
Abstract: The most recent major explosive eruption of the Santorini volcano in Greece—around 3600 years before present (B.P.), often referred to as the Minoan eruption—is one of the largest volcanic events known in historical time and has been the subject of intense volcanological and archeological studies [Druitt et al., 1999]. The submarine volcano Kolumbo, located seven kilometers northeast of Santorini and associated with Santorini's tectonic system, erupted explosively in 1650 A.D., resulting in fatalities on the island of Thera [Fouque, 1879]. A large fraction of the erupted products from the Minoan eruption has been deposited in the sea but, up to now, only has been studied in distal marine sediments.
As part of a collaborative project between the University of Rhode Island (Narragansett), the Hellenic Centre of Marine Research (Athens, Greece), and the Institute of Geology and Mineral Exploration (Athens), a marine geological survey was conducted around Santorini from April to June 2006. he new work now shows that the volume of the Minoan eruption may be comparable to that of the largest known historical eruption, the 1815 eruption of Tambora in Indonesia [Sigurdsson and Carey, 1989]; provides insights into the depositional processes and size of the Minoan eruption; and led to the discovery of important submarine hydrothermal vents with active mineralization.
TL;DR: The level of human involvement required for mapping concepts of the source ontologies to their intended meanings is explored and it is concluded that, although an effective fully automated process is not attainable, the process can be carried out efficiently with minimum human involvement.
TL;DR: In this article, the authors present an in-depth understanding of bank customers' buying behavior in relation to the selection process, and provide bank managers with useful insight into the development of high quality relationships with customers.
Abstract: Purpose – This project aims to offer an in‐depth understanding of bank customers' buying behaviour in relation to the selection process, and provide bank managers with useful insight into the development of high quality relationships with customers.Design/methodology/approach – The research involved a review of available literature on bank choice criteria, the fieldwork, the identification of factors that affect customers' choice, and the development of related managerial implications. A research questionnaire was administered by personal interviews to 1,092 bank customers in the greater area of Athens.Findings – Four distinct factors were identified as the main choice criteria that influence consumers' bank choice. Bank service quality is the most important element that customers consider in order to select their mortgage providers and establish a long‐term relationship with them. The other three refer to product attributes, access, and communication.Research limitations/implications – Limitations relate...
28 May 2006
TL;DR: The SCAP approach is language independent and that n-gram author profiles are better able to capture the idiosyncrasies of the source code authors, and is able to deal surprisingly well with cases where only a limited amount of very short programs per programmer is available for training.
Abstract: Source code author identification deals with the task of identifying the most likely author of a computer program, given a set of predefined author candidates This is usually based on the analysis of other program samples of undisputed authorship by the same programmer There are several cases where the application of such a method could be of a major benefit, such as authorship disputes, proof of authorship in court, tracing the source of code left in the system after a cyber attack, etc We present a new approach, called the SCAP (Source Code Author Profiles) approach, based on byte-level n-gram profiles in order to represent a source code author's style Experiments on data sets of different programming-language (Java or C++) and varying difficulty (6 to 30 candidate authors) demonstrate the effectiveness of the proposed approachA comparison with a previous source code authorship identification study based on more complicated information shows that the SCAP approach is language independent and that n-gram author profiles are better able to capture the idiosyncrasies of the source code authors Moreover, the SCAP approach is able to deal surprisingly well with cases where only a limited amount of very short programs per programmer is available for training It is also demonstrated that the effectiveness of the proposed model is not affected by the absence of comments in the source code, a condition usually met in cyber-crime cases
TL;DR: In this paper, the authors investigated the relationship between trait Neuroticism, state anxiety and intelligence and found that trait Neurotics were more likely to be affected by test anxiety and by induced anxiety.
TL;DR: In this article, the authors analyzed the mass customisation strategies developed by mobile phone operators and identified the types of customer value perceived by mobile users that customise services to their profiles.
Abstract: Purpose – To analyse the mass customisation strategies (MC) developed by mobile phone operators and to identify the types of customer value perceived by mobile phone users that customise services to their profiles.Design/methodology/approach – A customer‐centre approach was adopted for analyzing MC strategies that enhance both extrinsic and intrinsic customer value. A convenience sample was surveyed for gathering data regarding the customer value dimensions perceived by users of customised mobile phone services in Greece.Findings – Findings revealed that MC strategies that are customer centred are vital as, users of customised mobile phone services perceive both “give” and “get” customer value dimensions. As MC does not come for free, to persuade customers to get involved and invest time and effort in value chain operations for designing customised services, companies need to identify and provide enhanced customer values.Research limitations/implications – Research findings have great implications in the ...
TL;DR: In this paper, the dynamics of the changes are examined on a specific Greek island, Lesvos, which has an economic and landscape history typical of many Mediterranean cases, and the examination of these changes with a descriptive modelof landscape transformation offers some insightsin the dynamicsof landscapes and their characteristics in the Mediterranean today for present and future developments.
TL;DR: In this article, the impact of the three main airline business models (traditional scheduled, charter and low-cost) on regional airports using Britain as a case study is highlighted by focusing on the relationship between tourism and air transport.
TL;DR: In this paper, the authors investigate the response of society to the most extreme yet not implausible scenario, a five-metre sea level rise within a century, starting in 2030.
Abstract: There is an unknown but probably small probability that the West- Antarctic Ice Sheet (WAIS) will collapse because of anthropogenic climate change. A WAIS collapse could cause a 5-6 metre global sea level rise within centuries. In three case studies, we investigate the response of society to the most extreme yet not implausible scenario, a five-metre sea level rise within a century, starting in 2030. The case studies combine a series of interviews with experts and stakeholders with a gaming workshop. In the Rhone delta, the most likely option would be retreat, with economic losses, perhaps social losses, and maybe ecological gains. In the Thames estuary, the probable outcome is less clear, but would probably be a mix of protection, accommodation and retreat, with parts of the city centre turned into a Venice of London. A massive downstream barrier is an alternative response. In the Rhine delta (the Netherlands), the initial response would be protection, followed by retreat from
TL;DR: An atomistic-based progressive fracture model for simulating the mechanical performance of carbon nanotubes by taking into account initial topological and vacancy defects is proposed in this article, where the model has been applied to defected single-walled zigzag, armchair, and chiral nanotsubes subjected to axial tension.
Abstract: An atomistic-based progressive fracture model for simulating the mechanical performance of carbon nanotubes by taking into account initial topological and vacancy defects is proposed. The concept of the model is based on the assumption that carbon nanotubes, when loaded, behave like space-frame structures. The finite element method is used to analyze the nanotube structure and the modified Morse interatomic potential to simulate the non-linear force field of the C–C bonds. The model has been applied to defected single-walled zigzag, armchair and chiral nanotubes subjected to axial tension. The defects considered were: 10% weakening of a single bond and one missing atom at the middle of the nanotube. The predicted fracture evolution, failure stresses and failure strains of the nanotubes correlate very well with molecular mechanics simulations from the literature.
TL;DR: A new method for performing a risk analysis study of health information systems by exploiting the results of the CRAMM-based risk analysis for developing a Bayesian Network model, which presents concisely all the interactions of the undesirable events for the system.
TL;DR: In this article, the applicability of corporate social responsibility in the context of the European maritime sector and examines its application in the case of the Greek-owned short sea shipping companies is examined.
TL;DR: In this article, the authors investigated the aerosol optical properties, namely aerosol extinction optical thickness (AOT), Angstrom parameter and size distribution over the Eastern Mediterranean Basin, using spectral measurements from the recently established FORTH (Foundation for Research and Technology-Hellas) AERONET station in Crete, for the two-year period 2003-2004.
Abstract: In this study, we investigate the aerosol optical properties, namely aerosol extinction optical thickness (AOT), Angstrom parameter and size distribution over the Eastern Mediterranean Basin, using spectral measurements from the recently established FORTH (Foundation for Research and Technology-Hellas) AERONET station in Crete, for the two-year period 2003–2004. The location of the FORTH-AERONET station offers a unique opportunity to monitor aerosols from different sources. Maximum values of AOT are found primarily in spring, which together with small values of the Angstrom parameter indicate dust transported from African deserts, whereas the minimum values of AOT occur in winter. In autumn, large AOT values observed at near-infrared wavelengths arise also from dust transport. In summer, large AOT values at ultraviolet (340 nm) and visible wavelengths (500 nm), together with large values of the Angstrom parameter, are associated with transport of fine aerosols of urban/industrial and biomass burning origin. The Angstrom parameter values vary on a daily basis within the range 0.05–2.20, and on a monthly basis within the range 0.68–1.9. This behaviour, together with broad frequency distributions and back-trajectory analyses, indicates a great variety of aerosol types over the study region including dust, urban-industrial and biomass-burning pollution, and maritime, as well as mixed aerosol types. Large temporal variability is observed in AOT, Angstrom parameter, aerosol content and size. The fine and coarse aerosol modes persist throughout the year, with the coarse mode dominant except in summer. The highest values of AOT are related primarily to southeasterly winds, associated with coarse aerosols, and to a less extent to northwesterly winds associated with fine aerosols. The results of this study show that the FORTH AERONET station in Crete is well suited for studying the transport and mixing of different types of aerosols from a variety of sources, especially those associated with major dust events from the Sahara.
01 Jan 2006
TL;DR: In this paper, the authors present a description of the major features of the large-scale Mediterranean Sea circulation and the most important changes that have been observed in the physical oceanography of the basin.
Abstract: Publisher Summary This chapter presents a description of the major features of the large-scale Mediterranean Sea circulation and the most important changes that have been observed in the physical oceanography of the basin. It describes the basic circulation of the Mediterranean Sea that has long been recognized to be that of a concentration basin. The transformation of the inflowing Atlantic water to outflowing Mediterranean water is made through a thermohaline cell that involves the whole basin and leads to the formation of the Levantine Intermediate Water (LIW). The chapter discusses the oceanographic changes within the Mediterranean Basin concentrating mainly on the internal processes of the basin in relation to the regional forcing. It focuses on the large-scale thermohaline circulation of the Mediterranean and examines sub-basin processes when these are directly linked with deep water formation. It discusses two other key factors that are linked to the oceanic circulation, sea level variations and the wind–wave field.
TL;DR: The paper demonstrates the efficient use of hybrid intelligent systems for solving the classification problem of bankruptcy by means of genetic programming, and presentsicative classification results in terms of both, classification accuracy and solution interpretability.
Abstract: The paper demonstrates the efficient use of hybrid intelligent systems for solving the classification problem of bankruptcy. The aim of the study is to obtain classification schemes able to predict business failure. Previous attempts to form efficient classifiers for the same problem using intelligent or statistical techniques are discussed throughout the paper. The application of neural logic networks by means of genetic programming is proposed. This is an advantageous approach enabling the interpretation of the network structure through set of expert rules, which is a desirable feature for field experts. These evolutionary neural logic networks are consisted of an innovative hybrid intelligent methodology, by which evolutionary programming techniques are used for obtaining the best possible topology of a neural logic network. The genetic programming process is guided using a context-free grammar and indirect encoding of the neural logic networks into the genetic programming individuals. Indicative classification results are presented and discussed in detail in terms of both, classification accuracy and solution interpretability.
TL;DR: In this article, the similarities and differences between the traditions of naturalistic decision making and organizational decision making are examined, highlighting an area where these two pragmatic research paradigms overlap.
Abstract: This article examines the similarities and differences between the traditions of naturalistic decision making and organizational decision making Illustrative examples of successful NDM inquiry in healthcare organizations are reviewed, highlighting an area where these two pragmatic research paradigms overlap Not only do researchers in these areas aim to improve our understanding of decision making, they provide practical and realistic alternatives to laboratory-based research on decision making The article presents a number of propositions for future research on NDM and organizations
TL;DR: The authors evaluated the spelling of derived words by dyslexic adolescents and verified whether this was associated with lack of vocabulary and/or morphological knowledge, and found that dyslexics exhibited lower levels of morphology knowledge than age-matched controls but were equivalent with the reading level controls.
Abstract: This exploratory study aimed to evaluate the spelling of derived words by dyslexic adolescents and to verify whether this is associated with lack of vocabulary and/or morphological knowledge. A cross-sectional reading level-design was employed in order to determine differences in spelling, derivational morphology and vocabulary tasks between dyslexic students aged 13+ and age-matched and reading level matched control groups. The study confirmed a profound spelling impairment of dyslexic students in comparison with two control groups but this was not associated with poor vocabulary in relation with their age-peers. In contrast, they exhibited lower levels of morphological knowledge than age-matched controls but equivalent with the reading level controls. These results are interpreted in the light of current developmental models of spelling that support a reciprocal interaction between spelling and metamorphology.
Journal Article•
TL;DR: Under a suitable cost structure it is shown that, for fixed age of the installation and fixed buffer level, the optimal policy is of control-limit type.
Abstract: In this paper we consider a model consisting of a deteriorating installation that transfers a raw material to a production unit and a buffer which has been built between the installation and the production unit. The deterioration process of the installation is considered to be nonstationary, i.e. the transition probabilities may depend not only on the working conditions of the installation but on its age as well. The problem of the optimal preventive maintenance of the installation is considered. Under a suitable cost structure it is shown that, for fixed age of the installation and fixed buffer level, the optimal policy is of control-limit type. When the deterioration process is stationary, an efficient Markov decision algorithm operating on the class of control-limit policies is developed. There is strong numerical evidence that the algorithm converges to the optimal policy. Two generalizations of this model are also discussed.
TL;DR: In this article, the authors considered a model consisting of a deteriorating installation that transfers a raw material to a production unit and a buffer which has been built between the installation and the production unit.