Showing papers by "University of the Aegean published in 1991"
TL;DR: In this paper, the authors investigated the behavior of the stock market prices for a small capital market, as is the case of the Greek market, and found that the behaviour of stock market index is mainly related to alternative investment opportunities and socio-political factors, as compared to companies' profits and economic activity.
Abstract: This paper investigates the behaviour of the stock market prices for a small capital market, as is the case of the Greek market. The results suggest that the behaviour of the stock market index is mainly related to alternative investment opportunities and socio-political factors, as compared to companies' profits and economic activity.
47 citations
TL;DR: The longitudinal dynamics of protons in hydrogen-bonded chains is described with a one-component, one-dimensional model with a two-parameter doubly periodic on-site potential to well understand the microscopic behavior of the proton interbond and intrabond transfer.
Abstract: The longitudinal dynamics of protons in hydrogen-bonded chains is described with a one-component, one-dimensional model with a two-parameter doubly periodic on-site potential. Ionic and bonding defects are described as soliton solutions of this model. Their energy, momentum, mass, width, and charge are calculated in the continuum limit. Small-amplitude oscillating solutions of breather and envelope (or dark) soliton type have also been calculated. Exact kink-antikink solutions for the discrete system are obtained numerically using a very efficient technique based on well-known minimization procedures. Producing such accurate initial conditions, the defect dynamics are explored numerically for some realistic sets of the physical parameters of the model. The microscopic behavior of the proton interbond and intrabond transfer is thus well understood for the conservative, nondriven hydrogen-bonded chain.
38 citations
TL;DR: The difficulties arising from the use of statistical methodology, and particularly the limited goodness-of-fit of the regression models, are discussed in relation to the suitability of oligotrophic waters as ‘control sites’ in eutrophication studies.
Abstract: Standard statistical tests of nutrient variability in the euphotic layer of an oligotrophic system in the S.E. Aegean Sea were performed. Practical problems resulting from data handling, such as high errors associated with low concentrations, nonlinearity and interaction among variables were examined. The practical problems in the analysis of environmental data, arising from statistical limitations were considered: linear correlations between chlorophyll α and nutrients were found to be significant only for ammonia, and the multiple regression model was found to be of limited value as a tool for a description of the system. By contrast, principal component analysis contributed significantly to the interpretation of each variable. The difficulties arising from the use of statistical methodology, and particularly the limited goodness-of-fit of the regression models, are discussed in relation to the suitability of oligotrophic waters as ‘control sites’ in eutrophication studies.
30 citations
TL;DR: The parallel implementations of two well-known linear state-space filtering algorithms, namely the Kalman and the Lainiotis filters, in MIMD machines are studied from a computational standpoint and indicate that these algorithms can be implemented in parallel using a comparatively small number of processors.
18 citations
TL;DR: In this work, the most recent wind-discrete models and solution methods are presented and analyzed and their limitations are identified and a new simulation-aided wind-continuous model is introduced capable of remedying the above limitations.
Abstract: The present paper regards the location of obnoxious facilities in the context of a realistic environment. Efforts have been made in the past towards this direction, without much success as fas as the modeling is concerned. The prevailing meteorological conditions of the area under consideration, that evidently play an important role in the dispersion of pollution, either were completely ignored or inadequately considered. In this work, the most recent wind-discrete models and solution methods are presented and analyzed and their limitations are identified. A new simulation-aided wind-continuous model is introduced capable of remedying the above limitations. Finally, a generalization is proposed and discussed, regarding the introduction of the stack height as a decision variable in the relative model.
In dieser Arbeit werden zunachst die in neuerer Zeit entwickelten wind-diskreten Modelle und Verfahren zur Standortplanung fur unerwunschte, umweltbelastende Anlagen analysiert und die Grenzen dieser Ansatze fur die Losung praktischer Problemstellungen aufgezeigt. Basierend auf diesen Erkenntnissen wird ein simulations-basiertes Verfahren fur ein neues wind-stetiges Modell vorgestellt, das diese Schwachstellen uberwindet. Abschlieβend wird das Basis-Standortmodell durch Einbeziehung der Emissionshohe als Entscheidungsvariable erweitert.
11 citations
TL;DR: In this paper, the authors deal with the historical plausibility and analytical validity of what has come to be termed the corn model and suggest that a definite answer should be based on the logic of the material-produce comparisons.
Abstract: This paper deals with the historical plausibility and analytical validity of what has come to be termed the corn model. The ongoing debate is firstly reviewed. It is suggested that a definite answer should be based on the logic of the material-produce comparisons. Although these do not lead invariably to a sound application of the corn model neither do they constitute per se a sign of classicism. However, it is shown that before and after Ricardo, corn models of various sorts and logical stringency were developed in order to cope with the problem of (1) the determination of the rate of profit in the only basic sector of the economy, agriculture, independent of any valuation and (2) its primacy over the overall economy. Copyright 1991 by Oxford University Press.
9 citations
TL;DR: Initial results of an attitude survey on the security of medical information systems in Greece are reported, indicating a need to adopt methods, techniques and legislation providing sufficient security guarantees.
9 citations
TL;DR: In this article, it was shown that the complex Lorenz equations are algebraically integrable with respect to the Lie theory of extended groups and for the parameter values σ = 1 2, b = 1, r 1 = e 2 /2, r 2 = e/2, e arbitrary.
9 citations
TL;DR: The surface density of nitrates on the columns of the Parthenon, Greece, was determined at the end of the Athenian dry season as discussed by the authors, which is highly probable that this is a measure of the corrosion of marble by photochemically formed nitric acid and nitrates in the atmosphere of Athens.
7 citations
TL;DR: In this article, the proton transport in hydrogen-bonded chains is investigated for a one-component system in a doubly periodic on-site potential, where Ionic and bonding defects have been considered as soliton solutions of this model.
6 citations
01 Jan 1991
TL;DR: In this article, the effects of HNO 3 and NO 3 on Pentelic marble were investigated by drawing air through a bed of coarse and graded marble powder, washing the marble with deionized water, analyzing the ions in the wash by ion chromatography and using thermodynamic data from the literature.
Abstract: The low sulphur fuels burned in Athens and the high photochemical activity (high [NOs≥]/[NO] ratios, but low Q 3 concentrations because of a 20 hour per day traffic peak) could mean that the molar ratio of [NO 3 - /[SO 4 - ] in the atmosphere of Athens is often greater than one. This in turn, could mean that the adverse effects of HNO 3 and NO 3 - on marble monuments are relatively important. Nitric acid, nitrates, sulphates, chlorides etc. in the atiiAjtsphere of the Acropolis were sampled with a transition flow reactor and analysed by ion chromatography. Their effects on Pentelic marble are being investigated by drawing air through a bed of coarse and graded Pentelic marble powder, washing the marble with deionized water, analyzing the ions in the wash by ion chromatography and using thermodynamic data from the literature
TL;DR: In this article, a generalization of the method of rational Fourier-series approximations for nonlinear ordinary differential equations in galactic dynamics is presented, which describes simple families of periodic orbits with very good accuracy.
Abstract: We present the generalization of the method of rational Fourier-series approximations for nonlinear ordinary differential equations in galactic dynamics. In previous papers we presented the formulae which describe simple families of periodic orbits with very good accuracy. In this Letter we generalize our formulae to describe periodic orbits of any resonancem:n.
01 Jan 1991
TL;DR: In this article, the authors discuss the meaning of the emancipation in the labour mouvement tradition, and the emergence of apathy of the working people towards it, and apply critical systems methodologies with the objective of arousing emancipation interest.
Abstract: This paper deals with the prerequisite of active participation of stakeholders in an organization, in order to apply critical systems methodologies with the objective of arousing emancipatory interest. It discusses the meaning of the emancipation in the labour mouvement tradition, and the emergence of apathy of the working people towards it. The critical systems thinking is obliged to face this apathy in its attempt to motivate the emancipation interest.