Showing papers by "Technological Educational Institute of Western Macedonia published in 2011"
TL;DR: Microalgae are promising sources for novel products and applications and they can be used in the diet of humans and animals as natural foods with health benefits and can find use in the protection of the environment, as well as in pharmaceuticals, biofuel production and cosmetics.
Abstract: Microalgae are known for centuries, but their commercial large-scale production started a few decades ago. They can be grown in open-culture systems such as lakes or highly controlled close-culture systems, have higher productivity than the traditional crops and can be grown in climatic conditions and regions where other crops cannot be grown, such as desert and coastal areas. The edible microalgae are the green algae (chlorophyta) and the cyanobacteria. Microalgae contain substances of high biological value, such as polyunsaturated fatty acids, proteins, amino acids, pigments, antioxidants, vitamins and minerals. They are promising sources for novel products and applications and they can be used in the diet of humans and animals as natural foods with health benefits. Moreover, they can find use in the protection of the environment, as well as in pharmaceuticals, biofuel production and cosmetics.
214 citations
TL;DR: In this paper, three series of polymer nanocomposites, based on poly(d,l lactic acid) (PDLLA) and organically modified montmorillonite, were prepared by the melt and the solution intercalation technique.
Abstract: Three series of polymer nanocomposites, based on poly(d,l lactic acid) (PDLLA) and organically modified montmorillonite, were prepared by the melt and the solution intercalation technique. The first series was prepared by extrusion using different clay loadings. The second series of nanohybrids was obtained using montmorillonite modified with different types of alkylammonium surfactants in terms of carbon-chain lengths (i.e., 4, 8, 12, 16 and 18). In the third series of nanocomposites, the organic cation concentration of the surfactant was varying. Microcellular porous materials were, afterwards, fabricated from these three series of nanocomposites. The porous structures of pure and nanocomposite PDLLA were prepared by isothermal pressure quench using supercritical CO2 as foaming agent. The morphology of the produced porous materials was investigated by scanning electron microscopy (SEM). Image processing of the samples revealed that the final cellular structure is strongly related to clay loading and, both, the type and the organic cation concentration of the alkylammonium used for the modification of the clay. The results suggest that the size of the pores decreases and the cell density and bulk foam density increase with the increase of clay loading or the surfactant's carbon chain length or the cation concentration in clay. Clay dispersion seems to be enhanced by the supercritical treatment upon foaming.
48 citations
TL;DR: In this article, two new symplectic Partitioned Runge-Kutta (SPRK) methods with phase-lag of order infinity are derived, which are tested on numerical integration of Hamiltonian problems and on the estimation of the eigenvalues of the Schrodinger equation.
Abstract: New symplectic Partitioned Runge–Kutta (SPRK) methods with phase-lag of order infinity are derived in this paper. Specifically two new symplectic methods are constructed with second and third algebraic order. The methods are tested on the numerical integration of Hamiltonian problems and on the estimation of the eigenvalues of the Schrodinger equation.
46 citations
TL;DR: In this paper, a wide-angle X-ray diffraction was used to characterize poly(3-hydroxybutyrate) (PHB)/organically modified clay nanocomposites and their thermal degradation kinetics was investigated using thermogravimetric analysis at various heating rates.
40 citations
TL;DR: In this article, the incidence and levels of pesticide residues in peaches grown using Integrated Crop Management (ICM) methods in Pella and Imathia, districts of Macedonia, Northern Greece, are presented.
33 citations
TL;DR: In this paper, the wall paintings of post-Byzantine monuments from Kastoria town, northern Greece were analyzed by simultaneous thermal analysis (TG-DTG/DTA) and X-ray diffraction and supplementary by electron microscope (ESEM-EDX) and Raman spectroscopy.
Abstract: Several plaster samples were collected from the wall paintings of post-Byzantine monuments from Kastoria town, northern Greece. They were analysed mainly by simultaneous thermal analysis (TG-DTG/DTA) and X-ray diffraction and supplementary by electron microscope (ESEM-EDX) and Raman spectroscopy. Whitish and dark plaster layers were evident in most cases. Calcite, micas, and quartz were the dominant minerals, while dolomite, gypsum, and feldspar were detected as minor phases in most of the samples. Hydromagnesite and chlinochlore were also determined in a few samples. The utilisation of the results for chronological purposes (i.e. for assignment of different painting periods) was also suggested and the presence of dolomite and hydromagnesite could be characteristic for the provenance of the raw material. Gypsum was regarded mainly as a weathering product due to sulfation process, and secondly as a binding material of the plaster. The thermoanalytical results are in good agreement with the mineralogical data. The white plasters are categorized as hydraulic lime mortars, while the dark ones as natural pozzolanic mortars. Calcite and gypsum correlates well with their respective mass losses at certain temperature ranges and their Raman spectra are clearly detected. ESEM-EDX revealed fine calcareous components with aluminolisilicate aggregates and the application of the fresco technique either as a multi-layer or a single-layer plaster. The deterioration caused by salts (gypsum, halite, and nitratine) and micro-organisms was also determined. The detrimental effect of the salt crystallization and dissolution was also confirmed using the so-called Peltier-stage experiment.
29 citations
TL;DR: The determined compounds are: calcite, dolomite, gypsum, halite, nitratine, natron and mirabilite, all of which are related to temperature and humidity changes and moisture fluctuations inside the wall paintings of Kastoria.
25 citations
01 Jan 2011
TL;DR: In this work specially tuned Symplectic Partitioned Runge-Kutta (SPRK) methods have been considered for the numerical integration of problems with periodic or oscillatory solutions and methods with corresponding order up to fifth have been constructed.
Abstract: In this work specially tuned Symplectic Partitioned Runge-Kutta (SPRK) methods have been considered for the numerical integration of problems with periodic or oscillatory solutions. The general framework for constructing exponentially/trigonometrically fitted SPRK methods is given and methods with corresponding order up to fifth have been constructed. The trigonometrically-fitted methods constructed are of two different types, fitting at each stage and Simos’s approach. Also, SPRK methods with minimal phase-lag are derived as well as phase-fitted SPRK methods. The methods are tested on the numerical integration of Kepler’s problem, Stiefel-Bettis problem and the computation of the eigenvalues of the Schrodinger equation.
25 citations
TL;DR: In this article, a study was conducted to determine the flora of Mt Varnoudas pastures in NW Greece and to evaluate the seasonal and altitudinal variations in the chemical composition and energy content of herbage, during the years 2004 and 2005.
16 citations
TL;DR: In this article, an application of numerical modelling and experimental study as a means of the quantitative non-destructive evaluation (QNDE) of defects in conductive samples was investigated.
Abstract: Eddy current testing is one of the most widely used methods in non-destructive testing for the inspection of conductive materials. Numerical modelling of eddy current testing has emerged as an important approach alongside experimental studies. This paper investigates an application of numerical modelling and experimental study as a means of the quantitative non-destructive evaluation (QNDE) of defects in conductive samples. There are two methods of measuring eddy current response, more commonly by measuring the change in impedance of the eddy current probe coil, or as used in this work, by measuring the change in magnetic field directly using magnetic field sensors such as superconducting quantum interference devices, giant magneto resistance, or as in this case Hall sensors. Specifically, measurements made using an eddy current probe containing an excitation coil and a Hall sensor, experimentally obtained using an X–Y scanner table, are compared with a numerical (finite element method) model. The discrepancies between the experimental tests and the numerical models have been analysed and explained, which is an important factor in engineering applications of QNDE.
16 citations
TL;DR: In this article, the jets in a microquasar are modelled using a three-dimensional relativistic hydrocode (PLUTO), with the aim of investigating the appearance of equatorial radio emission.
Abstract: The jets in a microquasar are modelled using a three-dimensional relativistic hydrocode (PLUTO), with the aim of investigating the appearance of equatorial radio emission. A dynamical mechanism is explored whereby the bow shocks of the jets strongly affect the equatorial regions. The presence of an extended disc is assumed and its role proves to be important in producing equatorial emission. As a concrete example, we focus on the SS 433 microquasar, one of the most intensively studied objects in the Galaxy, for which equatorial emission has been repeatedly detected during the last decade.
TL;DR: In this paper, a full factorial design of experiments was used for that purpose and scanning electron microscopy was employed for dimensional characterization and determination of the chosen responses, which revealed that solution concentration and clay loading of nanocomposite were the most important parameters affecting the morphology of the fibrous webs.
Abstract: Electrospun mats of biodegradable polymer/clay nanocomposites were prepared in order to investigate the qualitative and quantitative correlations between electrospinning-related parameters and the fibrous morphology of the mats. A full factorial design of experiments was used for that purpose and scanning electron microscopy was employed for dimensional characterization and determination of the chosen responses. Statistical analysis revealed that solution concentration and clay loading of nanocomposite were the most important parameters affecting the morphology of the fibrous webs. This, subsequently, allowed prediction of the domain of these two parameter settings where purely fibrous morphology can be achieved and further allowed optimization of the process in the framework of response surface methodology (RSM). The structure and thermal behaviour of the nanocomposites were also characterized before and after electrospinning using X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. A multi-analyte platform is provided by the combination of RSM results for improving the nanofibrous quality and post-spinning characterization for predicting the overall performance of the electrospun web. Copyright © 2011 Society of Chemical Industry
TL;DR: This work develops a simple methodology that can be utilized to evaluate the uncertainty and errors control on routine methods used both by academic researchers or the industrial sector.
TL;DR: The grazing activities of indigenous sheep of the greek breed »Serres« was investigated in a typical lowland, and in a mountainous pasture in northern Greece during the vegetative period of 2008 and it was remarked significant effect of the pasturing month on grazing time, and resting time of sheep.
Abstract: The grazing activities of indigenous sheep of the greek breed »Serres« was investigated in a typical lowland, and in a mountainous pasture in northern Greece during the vegetative period (April-October) of 2008. Grazing time, resting and ruminating time, distance travel and air temperature in relation to pasturing month and altitude were examined. It was remarked significant effect (P<0.001) of the pasturing month on grazing time, and resting time of sheep. Mean grazing time was greater in the lowland (315.71 min/day ±4.57) than in the mountainous pasture (283.57 min/day ±4.79). On the contrary, the resting time and the distance travel of sheep were shorter in the lowland pasture. The resting time had significant (P<0.01) positive relationship to air temperature (r=0.777).
Proceedings Article•
01 Jan 2011
TL;DR: The acquired results indicate that the proposed modelling approach could be effectively used to predict the kerf geometry and the surface roughness in AWJM, thus supporting the decision making during process planning.
Abstract: This work presents a hybrid approach based on the Taguchi method and the Artificial Neural Networks (ANNs) for the modeling of surface quality characteristics in Abrasive Water Jet Machining (AWJM). The selected inputs of the ANN model are the thickness of steel sheet, the nozzle diameter, the stand-off distance and the traverse speed. The outputs of the ANN model are the surface quality characteristics, namely the kerf geometry and the surface roughness. The data used to train the ANN model was selected according to the Taguchi’s design of experiments. The acquired results indicate that the proposed modelling approach could be effectively used to predict the kerf geometry and the surface roughness in AWJM, thus supporting the decision making during process planning.
TL;DR: In this paper, a rare renal calculus with cystine and a common Ca-oxalate-apatite calculus was used to explore the applicability of these techniques.
Abstract: Micro-Raman and spatially resolved cathodoluminescence (CL) coupled to environmental electron microscope (ESEM) with energy dispersive spectrometry (EDS) are nondestructive techniques scarcely employed on renal calculi studies. This study used these techniques together with Electron Probe Micro-Analysis (EPMA), X-Ray diffraction (XRD), and Thermogravimetry (TG) to study a rare renal calculus with cystine and a common Ca-oxalate-apatite calculus in order to explore the applicability of these techniques. TG and XRD effectively determined the renal calculi, while ESEM and μ Raman provided useful information. The backscattering probe (BS) differentiates calculi with elements of dissimilar atomic masses such as P, S, and C. The authors inferred that the CL emission peaks at 325 (L-cystine-apatite) and 310 nm (Ca-oxalate) could be associated to oxygen hole center emission defects coupled with C—OH precursor bonds, while the CL spectral emission from the collagen proteins mask the hydroxyl-apatite spectra.
30 Sep 2011
TL;DR: A new open source SNMP manager application called SETH is presented, which includes MIB file parsing capabilities, automatic discovery of network topology and variable up to real-time probing frequency of network equipment in order to extract useful statistical information regarding network conditions.
Abstract: In this paper authors present a new open source SNMP manager application called SETH. This application includes the following major attributes over existing management tools: MIB file parsing capabilities, automatic discovery of network topology and variable up to real-time probing frequency of network equipment in order to extract useful statistical information regarding network conditions. Network information is acquired from network devices using real-time SNMP probes close to agent systems clock granularity. Then re-configurable network metrics are calculated and visualized. Additionally, SNMP trap or notification messages send by routers, indicating cases of network emergencies, are also recorded. Graphical visualization of metric values, network correlation functions and support for all SNMP protocol versions is also provided by the tool.
06 Apr 2011
TL;DR: A prototype high level synthesis framework is presented here, that automatically generates synthesizable RTL code from unaltered, high level programs, and it utilizes a patented intermediate compilation format to retain the algorithmic semantics of the source programs and allow for compiler transformations.
Abstract: The complexity of the contemporary digital circuits and systems, determines the need for higher specification abstraction and automatic circuit synthesis techniques to be adopted. A prototype high level synthesis framework is presented here, that automatically generates synthesizable RTL code from unaltered, high level programs. The framework is developed using compiler-generator and logic programming (thus formal) techniques, and it utilizes a patented intermediate compilation format to retain the algorithmic semantics of the source programs and allow for compiler transformations. The synthesis framework is evaluated via statistics from a number of real-life applications. The performance optimization of the compiled applications, including an MPEG engine, underlines the quality of the prototype design framework.
30 Sep 2011
TL;DR: The tool applies formal techniques to transform behavioral ADA specifications into RTL micro-architectures which then can be easily implemented by commercial RTL synthesizers.
Abstract: In this contribution, behavioral synthesis tools are used for hardware implementation of a cellular neural network with the ability to accomplish image processing tasks in real time. Behavioral synthesis tools such as the CCC HLS framework can deliver correct-by-construction RTL VHDL implementations of computation-intensive applications such as image processing and cellular neural networks. The tool applies formal techniques to transform behavioral ADA specifications into RTL micro-architectures which then can be easily implemented by commercial RTL synthesizers. Example applications such as, edge-detection, half toning and morphological operations, validate the presented contribution.
TL;DR: A meta-search third-party result ranking mechanism is proposed, which is capable of adapting over the continuous changes that occur on the web, providing in parallel personalized information acquisition considering the user's navigation behaviour.
Abstract: The aim of this paper is, in accordance with efficient web search service operation objectives, to propose enhancements to the sophistication of the functionality that can be offered by search engine services A meta-search third-party result ranking mechanism is proposed, which is capable of adapting over the continuous changes that occur on the web, providing in parallel personalized information acquisition considering the user's navigation behaviour Transparency is achieved for both personalization and web evolution adaptation mechanisms, requiring virtually none effort from the user's part In essence, the proposed meta search engine rates, re-organises and combines the results acquired from search services for a specific user information resource request in accordance with a weighted combination of a performance related factor (tightly related to the ranking of the web result as given by the search engine service) and a reliability related factor (corresponding to the user satisfaction stemming from the specific web result that he/she browses), while the performance of each search engine with respect to adequately adapting to the web evolution is taken into account For the evaluation of the web results reliability, a collaborative reputation mechanism is utilized, which helps estimating their quality and predicting their future usability, taking into account their past performance in consistently satisfying user expectations A set of results indicative of the efficiency of our proposed scheme is provided The Internet search services used were Google, MSN and Yahoo!
01 Jan 2011
TL;DR: The water quality assessment revealed that the concentrations of heavy and toxic metals and trace elements are, for most of the samples; bellow the allowable limits specified by the existing regulatory framework as discussed by the authors.
Abstract: Ground water samples collected from 21 wells located in the hydrogeological, coal-bearing basin of Sarigiol, Western Macedonia, Greece have been analysed for determining trace elements concentrations. The water quality assessment reveals that the concentrations of heavy and toxic metals and trace elements are, for most of the samples; bellow the allowable limits specified by the existing regulatory framework. The trace elements As, Cd, Cu, Zn, V, Co, Be, B and Al are detected in very low concentrations, while Τi and Sn are detected in very low to negligible concentrations. The elements Pb, Hg, Ni, Mo, Crtot and Ba are present in low concentrations. This is also the case for Sr, Te and Bi. For these elements the legal framework does not specify allowable limits. Concentrations closed to or above the allowable limits have been determined for Sb and Tl. In addition, samples of water that have been collected from certain parts of Sarigiol basin show concentrations above the allowable limits for Al, Be, Ni, Cr, Sr and Se. However, the enrichment ratio, compared to the allowable limits determined by laws and regulations, is very low. Based on the results presented and evaluated in this contribution, it is concluded that adverse impacts to the human and natural environment are not probable. The water pumped from the wells of the area can be used safely for irrigation and water supply.
19 May 2011
TL;DR: In this paper, the authors present field measurements for the electrical consumption for different buildings in a University Campus in Greece and compare the recorded data are analyzed and compared for a specific building with the corresponding obtained by an EPA software.
Abstract: The European Energy Performance of Buildings Directive (EPBD) requires a certain Energy Performance Assessment (EPA) to be conducted for each building, to obtain an Energy Performance Certificate. For this purpose several software tools have been developed enabling the audit and assess of either residential, or tertiary buildings and the calculation of the energy needs and energy consumption in line with EPBD. In practice, however, significant differences between the calculated results and measurements are usually recorded, especially for the electrical consumption, since most of the EPA tools calculate only part of the electric energy consumption in a building. Scope of the paper is to present field measurements for the electrical consumption for different buildings in a University Campus in Greece. The recorded data are analyzed and compared for a specific building with the corresponding obtained by an EPA software. Differences between the two approaches are discussed, while interesting remarks are made concerning the electrical load profiles of University buildings and the rational use of lighting and air-conditioning systems during non-working hours. From the analysis of the results proper electric consumption control strategies of the electrical loads can be proposed, utilizing intelligent control systems.