Showing papers by "Technological Educational Institute of Western Macedonia published in 2014"

Financial, governance and environmental determinants of corporate social responsible disclosure

Abstract: Purpose – The purpose of this paper is to investigate the vital determinants on the extent of corporate social responsibility (CSR) disclosure in a US context. The selected variables are CEO duality, the presence of women in the board, greenhouse gas (GHG) emissions, emission reduction initiatives, company's risk premium, financial leverage and industry's profile. Design/methodology/approach – The environmental, social and governance (ESG) disclosure score is used as a proxy for the extent of CSR disclosure calculated by Bloomberg. The influence of plausible variables on the ESG disclosure score and its sub-categories was examined by using the least squares dummy variable model (LSDV) incorporating 100 companies listed on Standard & Poor's 500 Index for the period 2009-2012. Findings – The results show that the emission reduction initiatives and GHG emissions influence positively the extent of ESG score. In addition, slight differences exist concerning the determinants of different types of disclosures. F...

Effect of Nanoclay Hydrophilicity on the Poly(lactic acid)/Clay Nanocomposites Properties

Abstract: In order to improve poly(lactic acid) (PLA) mechanical, thermal, and barrier properties, different layered silicate nanoclays are added. This work deals with the study of the effect of the type of nanoclays with different hydrophilicity on the preparation procedure and properties of PLA nanocomposites. Six kinds of clays have been loaded in PLA whose hydrophilicity varies in the following order of increased hydrophilicity: modified Dellite 67G (67G) < Cloisite 15A (C15A) < C20A < C93A < C30B < hydrophilic smectite clay (HPS). Resultant nanocomposites have been characterized both with respect to bulk and surface properties by mechanical, rheological, thermal analyses, X-ray diffraction study, Fourier transform infrared spectroscopy, gas permeability tests, contact angle measurements, scanning electron microscopy, and atomic force microscopy. Antimicrobial properties have been also tested. Evidenced was the dependence of most properties on the hydrophilicity/hydrophobicity of the clays. The nanocomposites c...

Foreign Direct Investments, Exports, and Economic Growth in Croatia: A Time Series Analysis☆

Abstract: This paper studies the relationship between foreign direct investments, exports, and economic growth in Croatia using annual time series data for the period 1994-2012. Several econometric models are applied including the bounds testing (ARDL) approach and the ECM-ARDL model. The results confirm a bidirectional long run and short run causal relationship between exports and growth. These results offer new perspectives and insight for a new policy in Croatia for a sustainable economic growth.

Construction of exponentially fitted symplectic Runge-Kutta-Nyström methods from partitioned Runge-Kutta methods

Abstract: In this work we derive exponentially fitted symplectic Runge-Kutta-Nystrom (RKN) methods from symplectic exponentially fitted partitioned Runge-Kutta (PRK) methods methods (for the approximate solution of general problems of this category see [18] - [40] and references therein). We construct RKN methods from PRK methods with up to five stages and fourth algebraic order.

A Simple Route for Purifying Extracellular Poly(3-hydroxybutyrate)-depolymerase from Penicillium pinophilum

Abstract: This work proposes the purification of an active and efficient enzyme, extracellular poly(3-hydroxybutyrate) (PHB)-depolymerase, suitable for industrial applications. This is achieved by the application of an easy, fast, and cheap route, skipping the chromatography step. Chromatography with one or two columns is a common step in the purification procedure, which however renders the isolation of the enzyme a time consuming and an expensive process. A strain of the fungus Penicillium pinophilum (ATCC 9644) is used for the isolation of extracellular PHB-depolymerase. The molecular weight of the purified enzyme is about 35 kDa and is estimated by gel electrophoresis (SDS-PAGE, 12% polyacrylamide). The enzymatic activity of the isolated enzyme is determined to be 3.56-fold similar to that found by other researchers that have used chromatography for the isolation. The as-isolated enzyme disintegrates the poly(3-hydroxybutyrate) (PHB) films successfully, as it is demonstrated by the biodegradation test results provided here.

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.

The Role of Agriculture in Economic Growth: A Comparison of Mediterranean and Northern Views in Europe

Abstract: The main objective of this paper is to identify the causal relationship that exists between agricultural value added per worker and Gross Domestic Product per capita in Europe. More specifically, the role of agriculture in economic growth is examined with special emphasis to the differences and similarities among Mediterranean and Northern countries. In order to examine short-run and long-run relationships, recent methods of linear co-integration are employed while the role of agricultural value added in economic growth is also examined by Granger causality tests. Results show a bi-directional relationship between agricultural value added and economic growth in the northern EU countries and only in one Mediterranean country. From a policy point of view, this relationship is of crucial importance since it can facilitate successful economic decisions. Taking into consideration that the role of agriculture in economic growth is an issue that always attracts the interest of scholars, this research could be prove extremely interesting and useful. Especially for this period of economic crisis, when the whole growth approach is reexamined and reevaluated, the research findings provide evidence that agriculture can lead as an engine of growth in several EU countries and can play stabilizer's role in the whole EU economy.

Exploring Student Viewing Behaviors in Online Educational Videos

Abstract: Online video use in education is an expanding trend and research that focuses on how students view educational videos becomes of particular interest. In our previous work, we argued that in order to conduct a detailed analysis of the learner viewing behavior we have to deploy tools that log the learner activity and assist statistical analysis and data mining. Working towards this direction, a framework for recording and analyzing learner behavior was presented. This paper presents findings of applying this framework into educational settings.

A Comparative Study of Pigments from the Wall Paintings of Two Greek Byzantine Churches

Abstract: The goal of this study was to characterize pigments used in the murals of two Byzantine churches, from Kastoria, northern Greece. The identification of the iconographer was also investigated by comparing the pigments applied in the wall paintings of the churches. Pigment microsamples of various colors were collected and analyzed by environmental scanning electron microscopy coupled with an energy dispersive system to characterize the elemental composition. Raman spectroscopy was employed to collect molecular spectra for characterization of mineralogical phases. Hematite, cinnabar, and minium were identified in red surfaces. Brown and yellow colors were assigned to mixtures of iron oxides, iron hydroxides, and calcite. Mixtures of iron, lead, and mercury compounds were used to produce different hues in the murals. Black tones were prepared primarily using charcoal and bone black. Grey colors were produced by a mixture of black carbon with calcite; blue hues, by a mixture of iron oxides, calcite, and black ...

A fuzzy controller for rate adaptation in MPEG-DASH clients

Abstract: The MPEG-Dynamic Adaptation Streaming over HTTP (MPEG-DASH) tries to improve the quality perceived by the user by allowing the user's centric access to different resolutions of the video content via the Hypertext Transfer Protocol (HTTP). However, although it eliminates data packet loss, depending on the rate adaptation strategy adopted by the user, as well as, the network conditions, there may be playback interruptions. In this paper a novel MPEG-DASH adaptation scheme, the FDASH, is proposed, which, by employing fuzzy logic to control the buffering time and the resolution achieves the following: a) distributes the best possible resolution of video segments, b) delivers undisrupted video playback as a result of buffer underflows at the client, c) avoids unnecessary changes of video resolution owing to frequent fluctuations of the available connection throughput. Simulation results showed that the FDASH in comparison with other schemes succeeds in various network scenarios in providing the client with the best possible video rates avoiding buffer underflows and frequent changes of video resolution.

Biopolyester-based nanocomposites: Structural, thermo-mechanical and biocompatibility characteristics of poly(3-hydroxybutyrate)/montmorillonite clay nanohybrids

Abstract: In this work, the structural, thermal, mechanical, and biocompatibility characteristics of biopolyester-based nanocomposites with phyllosilicate clays, namely those of poly(3-hydroxybutyrate) (PHB) with octadecylamine-modified montmorillonite (C18MMT), are reported. PHB/clay nanocomposites with various loadings were prepared by melt mixing. X-ray diffraction measurements and transmission electron microscopy images revealed the coexistence of intercalated and exfoliated states in the produced nanocomposites. Atomic force microscopy imaging also shed light to the morphological characteristics of the pure PHB and the prepared nanocomposites. The thermal stability of the nanohybrid materials was improved with the 5 wt % loading nanocomposite to show the best improvement. In addition, the nanohybrids have lower melting point compared to pure PHB and enhanced storage modulus (E′). Finally, the biocompatibility of pristine PHB and the 5 wt % nanocomposite was assessed by studying the morphology and proliferation of osteoblast cells attached on their surfaces. The results after 3 and 7 days of cell culturing indicate the incorporation of nanoclays does not change the cell adhesion and spreading as compared to those on pure PHB. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41628.

Valorization of Mill Scale Waste by its Incorporation in Fired Clay Bricks

Abstract: The mill scale (MS) waste is produced in steel industry during the milling process from the rapid oxidization of the hot iron products, and is mainly consisted of iron oxides (>95%). The aim of this work is to evaluate the utilization of MS (known in Greece as “kalamina”) as an admixture in clay bricks manufacturing by applying extrusion and sintering processes. For that purpose, specimens were formed from various clay/MS mixtures (up to 9 wt% MS) and then fired at different temperatures (up to 1100°C). Shrinkage and weight loss upon firing as well as density, porosity, bending strength and thermal conductivity of sintered specimens were determined and studied as a function of the % MS content and the firing temperature for optimization. The experimental results show that the incorporation of MS in clay bricks production is feasible, as an efficient secondary resource, thus turning waste from one industry into useful feedstock for another one. Specifically, the mechanical performance and thermal conductivity are not significantly affected with increasing the mineral admixture percentage and the sintering temperature.

The Contribution of Industrial Minerals to Sustainable Recovery of Greek Economy

Abstract: Industrial Minerals and Rocks are the raw materials of economic value that are not classified as metallic minerals, fossil fuels or precious stones. The production and export potential of domestic perlite reveal Greece as a leader both at European and at global level as well as other industrial minerals such as bentonite and magnesite, which also could contribute by a distinctive manner to the economic development of the country. The quality, however, and the processing expertise are important factors in producing special products to meet the needs and market requirements for specific end uses, specifically rare earth elements (REE) as critical strategic minerals in high-tech products. Occurrences and industrial mineral deposits, primarily in North Greece, are examined in relation to their uses, such as feldspars, pozzolan, pumice, kaolin, zeolites, quartz, gypsum, white carbonates.

A Benchmark Problem for Eddy Current Nondestructive Evaluation

Abstract: Currently, there are three TEAM Workshop benchmark problems involving eddy current nondestructive evaluation configurations, Nos. 8, 15, and 27. Regarding the first two, they have ceased to constitute challenging problems since they can be routinely solved with existing commercial software. In this paper, we present precision impedance measurements in a configuration involving a system of plates with through holes and a crack and propose them for benchmarking numerical codes. The benchmark represents a simplified version of eddy current inspection of fastener holes in aircraft structures, provides a lot of experimental data, and overall constitutes a more challenging problem.

Nanocomposites of poly(3‐hydroxybutyrate)/organomodified montmorillonite: Effect of the nanofiller on the polymer's biodegradation

Abstract: Poly(3-hydroxybutyrate) (PHB) is a biopolymer that can be degraded by extracellular PHB depolymerase. This enzyme is secreted by various microorganisms, but bacterial PHB depolymerases are the most widely studied. The biodegradability rate depends on various factors. By controlling them, the biodegradability rate can change and be customized, and thus, the applications of the polymer can increase and become more diverse. In this work, the role of organomodified montmorillonite (OMMT) on PHB biodegradation was investigated. Using the melt-mixing method, nanocomposites of PHB and OMMT as the nanofiller were prepared. The enzyme was isolated from the fungus Penicillium pinophilum and the enzymatic degradation was studied for both pure polymer and its nanocomposites. It was found that, after 25 days of enzymatic degradation, the mass loss was very low, while the polymer's average molecular weight as measured by gel permeation chromatography was significantly reduced (more than 50%). Additional peaks corresponding to PHB oligomers (from pentamers to nonamers) appeared after biodegradation. This behavior was observed for pure PHB and the hybrid materials. Scanning electron microscopy imaging of the biodegraded surfaces and analysis of these images showed that the higher amount of nanoclay (10 wt %) resulted in larger biodegraded area of the specimens. The results presented here demonstrate that the presence of the nanoclays enhances the biodegradation rate of pure PHB polymer and provide quantitative data for the biodegradation of PHB/organoclay hybrid materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41656.

Asymmetric Velocity Distributions from Halo Density Profiles in the Eddington Approach

Abstract: In the present paper we show how obtain the energy distribution f(E) in our vicinity starting from WIMP density profiles in a self consistent way by employing the Eddington approach and adding reasonable angular momentum dependent terms in the expression of the energy. We then show how we can obtain the velocity dispersion and the asymmetry parameter {\beta} in terms of the parameters describing the angular momentum dependence. From this expression for f(E) we proceed to construct an axially symmetric WIMP velocity distributions, which for a gravitationally bound system automatically has an velocity upper bound and is characterized by the the same asymmetries. This approach is tested and clarified by constructing analytic expressions in a simple model, with adequate structure. We then show how such velocity distributions can be used in determining the event rates, including modulation, both in the standard as well directional WIMP searches. find that some density profiles lead to approximate Maxwell-Boltzmann distributions, which are automatically defined in a finite domain, i.e. the escape velocity need not be put by hand. The role of such distributions in obtaining the direct WIMP detection rates, including the modulation, is studied in some detail and, in particular, the role of the asymmetry is explored.

Application of μRaman Microscopy to the Identification of Individual Airborne Particles: Preliminary Results from Kozani's Area, Northern Greece

Abstract: In the present study, Raman spectroscopy combined with a con-focal microscope has been applied for the identification of airborne particulate matter collected from Kozani's area, northern Greece. This technique provided a rapid and accurate identification of the molecular composition of micrometer sized (down to 2 µm) airborne particles. Different experimental conditions (laser excitation wavelength of 532 and 780 nm, slit and pinhole aperture, 50× and 100× objectives, number of exposures, and time of each exposure) were employed in order to obtain the optimal analytical parameters. The slit aperture and the 532 nm laser source were preferable. Removal of the background interference caused by the blank Teflon filter was performed for the acquisition of Raman spectra of minute ( 10 µm). Several distinct mineral phases were determined, such as: the common geogenic minerals calcite, gypsum, anhydrite, titanium ox...

The European Banking System Before and After the Crises

Abstract: The European banking system is not isomorphic. The differences can be traced to the differences in their local economy development, legal origin, ownership status, corporate governance system, etc. The 2008 crises has found the banking system of Europe in a transition status. The adoption of Euro, the establishment of the European Central Bank, the Basil III initiative, the adoption of legal isomorphism as policy in E.U., and finally the crises have been creating a unique environment for the banking system. The paper will address the issue of convergence of the banking system in Europe using a set of data from 27 countries of Europe. The analysis shows that the banks haven't changed their financial and ownership structure. Some changes in strategy are not adequate to formulate the opinion that the banking sector in Europe is different than the one before it.

Post–acquisition performance of European cross–border bank M&As

Abstract: The banking industry has been alleged to be at the epicentre of mergers and acquisitions (M&As) for several decades. Though the short–term wealth effects of M&As have been extensively explored in the last decades, the long–term share price and operating performance is relatively under–researched. The current study attempts to investigate the post–event share price behaviour of a sample of acquiring firms involved in cross–border bank mergers. Using financial ratios, we also probe into the long–term operating performance of acquiring firms up to five years following the acquisition. The results show that acquiring firms experience a gradual positive price reversal up to two years subsequent to mergers. In addition, the financial performance seems to be improved in parallel to the market value. We conclude that cross–border bank mergers seem partially to benefit the acquiring firms in the long–term when synergistic gains from consolidation come to reality.

S.A.T.E.P. : Synchronous-Asynchronous Tele-education Platform

Abstract: S.A.T.E.P. means Synchronous Asynchronous Tele education Platform is a software application for educational purposes, with a lot of parametrizing features written entirely from scratch. It aims at the training and examination of computer skills, a platform that can be adjusted to the needs of each lesson. In the application the trainer and the administrator can define the number of the lectures and upload files for each one of them. Furthermore, he can insert, modify and delete questions which are used for evaluation tests but also for the trainees examinations. The trainee can read and download the files of each lesson and also test his knowledge on what he has studied through a series of questions. A chat module where registered users as well as system administrator can discuss and solve questions is also developed.

Automated drawing system of quantum energy levels

Abstract: The purpose of this work is to derive an automated system that provides advantageous drawings of energy spectra for quantum systems (nuclei, atoms, molecules, etc.) required in various physical sciences. The automation involves the development of appropriate computational code and graphical imaging system based on raw data insertion, theoretical calculations and experimental or bibliographic data insertion. The system determines the appropriate scale to depict graphically with the best possible way in the available space. The presently developed code operates locally and the results are displayed on the screen and can be exported to a PostScript file. We note its main features to arrange and visualize in the available space the energy levels with their identity, taking care the existence in the final diagram the least auxiliary deviations. Future improvements can be the use of Java and the availability on the Internet. The work involves the automated plotting of energy levels in molecules, atoms, nuclei and other types of quantized energy spectra. The automation involves the development of an appropriate computational code and graphical imaging system.

A Floating-Point Paradigm for High-level Synthesis

Abstract: The current difficulty to deliver complex digital integrated circuits (ICs) on time in the market has created the need for formal, fully automated and rapid methods for designing and developing such products. These methods exploit approaches such as compiler technology, High-level Synthesis (HLS) and Electronic System Level (ESL) flows to handle such complexity. Designing custom VLSI hardware units motivate for developing large arithmetic blocks such as floating-point units, using HLS tools. Here, the formal and automated CCC high-level synthesis tools are used in the floating-point paradigm. The CCC tools generate provably-correct floating-point blocks due to the formality of the method, in order to avoid time-consuming RTL and gate-level simulations. The floating-point operations are coded in the ADA programming language and competitive hardware performance is delivered from the rapid CCC compiler experiment, therefore the presented approach is proven useable.

LTE-A interworking for seamless service provisioning

Abstract: Following the Always Best Connection (ABC) principle of the 4th generation wireless networks users of mobile services would be provided with connectivity to the best access technology all the time. In such a context mobile devices are equipped with multiple radio interfaces allowing connectivity to the most suitable network environment based on users requirements and operators policies. Seamless vertical handover plays the key role for mobility across various access networks offering service continuity to users. In this paper seamless handover solutions are presented between 3GPP (Third Generation Partnership Project) and non-3GPP wireless access technologies utilizing functionalities of the Evolved Packet Core (EPC) network of the LTE-A, as well as, of the IEEE 802.21 standard. The schemes presented provide low latencies while supporting services QoS constraints, as well as, user requirements and provider policies.

Establishing an assessment framework for energy sustainability in prisons: The E-SEAP project

Abstract: Prison sites are a special type of public buildings or facilities in general that are overlooked by policy makers. The prison size and constant energy use results in excessive energy consumptions, which implies that a focus on such sites is necessary. Most authorities rather focus on the security aspects of prison estates than their energy efficiency, and this is transferred naturally to all members of the prison community, i.e. staff and their families, prisoners and their families and wider community. In this context, the European Sustainable Energy Award for Prisons (E-seaP) is an Intelligent Energy Europe project that deals with the sustainable energy behavior of prison sites in 8 European regions. The main goal is to devise an assessment framework for energy sustainability in prisons using a holistic approach, which takes into consideration not only the building energy management but also the provision for education and training and the wider community impact. This paper presents the adopted assessment framework along with a comparison of energy consumption in 17 prison sites in Europe. The assessment procedure may be adapted for use also in other types of public buildings.

Enhanced Visual Analytics Services for the Optimal Planning of Renewable Energy Resources Installations

Abstract: This paper presents an integrated and novel service environment for real-time interactions between users, as well as enhanced visualization and decision support services over extremely large volumes of heterogeneous Renewable data sources. The integrated visual analytics methods, allow energy analysts to incorporate their expert knowledge into the analysis, so as to dynamically investigate the observed events and locations, and accurately identify the preferable results. The goal of visual analytics research is to turn the information overload into an opportunity by enabling decision-makers to examine this massive amount of information to make effective decisions.