Technological Educational Institute of Western Macedonia

About: Technological Educational Institute of Western Macedonia is a based out in . It is known for research contribution in the topics: Catalysis & Symplectic geometry. The organization has 291 authors who have published 522 publications receiving 7682 citations. The organization is also known as: TEI of West Macedonia & TEI of Western Macedonia.

Assessing productivity change with SFA in the sheep sector of Greece

Abstract: The objective of this paper is to measure total factor productivity growth in a panel of sheep farms in Greece and assess the relative contribution of technical change, technical efficiency change and scale efficiency change in observed productivity growth. Such decomposition can be useful in planning well defined policies which can support the sector’s sustainable development via the optimization of input/output use. A stochastic frontier production function approach is adopted and maximum likelihood is used to estimate the parameters. The data used for the econometric estimation are obtained from the Greek Farm Accounting Data Network for the period 1997–2002. TFP has been growing in the sector but at a diminishing rate. The major determinant of productivity growth is technical change, which has been shifting the frontier by 2.4% on average during this period, but is counteracted to some extent by technical and scale inefficiency each reducing TFP growth by about 0.3% p.a.

Attack, Interact, and Mobilize: Twitter Communication Strategies of Greek Mayors and their Effects on Users’ Engagement

Abstract: The aim of the present study is to examine the communication strategies used by Greek mayors in Twitter across different periods of an electoral cycle (pre-campaign, campaign, and post-campaign). Moreover, this study tries to delineate the effects of Twitter strategies on users’ engagement and identify the most effective ones. To that end, a content analysis is performed on 32,810 tweets of Greek mayors for a six-year period. Moreover, quantitative metrics such as the number of favorites and retweets are also obtained for each tweet. Results suggest that Greek mayors mainly use Twitter as a press release bulletin board for dissemination of information about the main events taking place in municipality. Moreover, they also use impression management strategies to promote a distinct personal, political and professional image. Results also show that during different periods of an electoral cycle mayors utilize a different mix of Twitter strategies. Furthermore, aggressive (attacking opponents), interactive (direct communication), and mobilization (requesting feedback) strategies are found to be the most effective in enhancing followers’ attitude expression (favorites) and advocacy behavior (retweets). The present study provides valuable practical implications for social media political marketers as well as politicians.

Numerical Solution of the two-dimensional time independent Schrödinger Equation by symplectic schemes†

Abstract: The solution of the two-dimensional time-independent Schrodinger equation is considered by partial discretization. The discretized problem is treated as an ordinary differential equation problem and solved numerically by asymptotically symplectic methods. The problem is then transformed into an algebraic eigenvalue problem involving real, symmetric matrices. The eigenvalues of the two-dimensional harmonic oscillator and the twodimensional Henon-Heils potential are computed by the application of the methods developed. The results are compared with the results produced by full discretization. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Coupled approach VIM-BEM for efficient modeling of ECT signal due to narrow cracks and volumetric flaws in planar layered media

Abstract: Rapid and accurate modeling of Eddy Current Testing (ECT) signal is required in many industrial areas. For example, crack detection via ECT is widely employed in aeronautics and aerospace industry to inspect riveted planar multilayered structures. In these structures, small narrow cracks (e.g. micro-cracks) may initiate at the edge of rivet holes (which can be considered as large volumetric flaws) and propagate through the PMS. This paper proposes a new and efficient model, based on a coupled approach between Volume Integral Method (VIM) and Boundary Element Method (BEM), simulating ECT probe signals due to the presence of both narrow cracks located near volumetric flaws within a given PMS. Simulation results are compared with experimental and simulated signals obtained with a numerical code. The performance of the method, in terms of accuracy and computational time, is discussed and the perspectives opened are presented.

Sustainable operation of a biological wastewater treatment plant

Abstract: The sustainable operation of a biological wastewater treatment plant is significantly linked to its removal efficiency, cost of sludge management, energy consumption and monitoring cost. The biological treatment offers high organic removal efficiency, it also entails significant sludge production, which contains active (live) and inactive (dead) microorganisms and must be treated prior to final disposal, in order to prevent adverse impact on public health and environment. The efficiency of the activated sludge treatment process is correlated to an efficient solid-liquid separation, which is strongly depended on the biomass settling properties. The most commonly encountered settling problems in a wastewater treatment plant, which are usually associated with operating conditions and specific microorganisms growth, are sludge bulking, floating sludge, pin point flocs and straggler flocs. Sustainable management of sludge and less energy consumption are the two principal aspects that determine the operational cost of wastewater treatment plants. Sludge treatment and management accumulate more than 50% of the operating cost. Aerobic wastewater treatment plants have high energy requirements for covering the needs of aeration and recirculations. In order to ensure wastewater treatment plants' effective operation, a large number of physicochemical parameters have to be monitored, thus further increasing the operational cost. As the operational parameters are linked to microbial population, a practical way of wastewater treatment plants' controlling is the microscopic examination of sludge, which is proved to be an important tool for evaluating plants' performance and assessing possible problems and symptoms. This study presents a biological wastewater treatment plant with almost zero biomass production, less energy consumption and a practical way for operation control through microbial manipulation and microscopic examination.