Evaluation of polyesters from renewable resources as alternatives to the current fossil-based polymers. Phase transitions of poly(butylene 2,5-furan-dicarboxylate)

Poly(butylene 2,5-furan dicarboxylate) (PBF) is an alipharomatic polyester that can be prepared using monomers derived from renewable resources such as 2,5-furan dicarboxylic acid and 1,4-butanediol. In the present work the thermal behavior of PBF was studied. Multiple melting was observed during heating traces of samples isothermally crystallized from the melt using differential scanning calorimetry (DSC). The wide angle X-ray diffraction (WAXD) patterns did not reveal the presence of a second crystal population, or a crystal transition upon heating. DSC study showed that the phenomena are closely related to recrystallization. Temperature modulated DSC (TMDSC) tests indeed evidenced enhanced recrystallization. The equilibrium melting point was estimated to be 184.5 °C using the linear Hoffman–Weeks extrapolation. The heat of fusion of the pure crystalline polymer was found equal to 129 J/g or (27.35 kJ/mol), a little lower than that of PBT. The Lauritzen–Hoffman secondary nucleation theory was used and the surface energy values and the work of chain folding were found to be comparable to those of PBT, but quite lower than those of poly(ethylene terephthalate) (PET). The non-isothermal crystallization on cooling and the cold-crystallization of quenched samples were also studied. Condensed spherulites were observed on isothermal crystallization under large supercoolings by using polarized optical microscopy (POM), while the spherulites turned to ring-banded morphology at higher temperatures. In every case the nucleation density was high.     

Synthesis of ferronickel slag-based geopolymers

This paper deals with the synthesis of geopolymers utilizing ferronickel slag as raw material. The utilized slag is produced in the Greek plant LARCO during the pyrometallurgical treatment of laterites for the production of ferronickel, specifically at the step of the reductive smelting in electric arc furnaces. The performed work includes the optimization of the slag-based geopolymeric system through the study of the effect of the synthesis parameters on the mechanical properties of the produced materials. The structure of geopolymers was determined with X-ray diffractometry (XRD), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The obtained results showed that the ferronickel slag is an excellent raw material for the production of inorganic polymers using the geopolymerization technology. The materials produced under the optimum synthesis conditions were compact and rigid and presented high compressive strength (118 MPa), as well as extremely low water absorption (0.7–0.8%).     

Derivation of algorithms for cutwidth and related graph layout parameters

In this paper, we investigate algorithms for some related graph parameters. Each of these asks for a linear ordering of the vertices of the graph (or can be formulated as such), and constructive linear time algorithms for the fixed parameter versions of the problems have been published for several of these. Examples are cutwidth, pathwidth, and directed or weighted variants of these. However, these algorithms have complicated technical details. This paper attempts to present ideas in these algorithms in a different more easily accessible manner, by showing that the algorithms can be obtained by a stepwise modification of a trivial hypothetical non-deterministic algorithm. The methodology is applied to rederive known results for the cutwidth and the pathwidth problem, and obtain new results for several variants of these problems, like directed and weighted variants of cutwidth and modified cutwidth.     

Unveiling the underlying relationships over a network for monitoring purposes

Nowadays traffic monitoring and analysis tools provide poor information about traffic volume without giving any clear view of what the hidden rules and relationships that govern these flows are. Since the majority of flows is generated by services (web browsing, email, p2p) and most of these applications are dependent on many network assets (servers and databases) we should discover the underlying relationships of every application. We present a technique that discovers the hidden relationships among components of a network that consist of parts of specific applications. From time information and flow attributes, such as IP addresses and service ports, our method using a novel hybrid genetic algorithm produces a small set of fuzzy rules that can reveal the underlying relationships over a network without any guidance. These dependencies build a service graph which can become a useful tool for fault localization, monitoring service performance, designing changes and anomaly detection. Copyright © 2009 John Wiley & Sons, Ltd.     

A knowledge-based approach to user interface adaptation from preferences and for special needs

Moving between devices is omnipresent, but not for people with disabilities or those who require specific accessibility options. Setting up assistive technologies or finding settings to overcome a certain barrier can be a demanding task for people without technical skills. Context-sensitive adaptive user interfaces are advancing, although migrating access features from one device to another is very rarely addressed. In this paper, we describe the knowledge-based component of the Global Public Inclusive Infrastructure that infers how a device shall be best configured at the operating system layer, the application layer and the web layer to meet the requirements of a user including possible special needs or disabilities. In this regard, a mechanism to detect and resolve conflicting accessibility policies as well as recommending preference substitutes is a main requirement, as elaborated in this paper. As the proposed system emulates decision-making of accessibility experts, we validated the automatic deduced configurations against manual configurations of ten accessibility experts. The assessment result shows that the average matching score of the developed system is high. Thus, the proposed system can be considered capable of making precise decisions towards personalizing user interfaces based on user needs and preferences.     

Geotechnical Problems of Cultural Heritage due to Floods

Flood events demonstrate devastating effects not only on materials and structures in contact with flowing surface water. Equally important is the behavior of foundations in interaction with subsoil. This contribution gives an overview of different phenomena which arise in subsoil and at the foundation level during the groundwater rise accompanied by several case histories related to cultural heritage. Possible geotechnical measures are discussed as well.     

Renewable energy sources (RES) projects and their barriers on a regional scale: The case study of wind parks in the Dodecanese islands, Greece

The increasing energy challenges faced, in particular, by isolated communities, such as insular communities, call for an integrated, flexible and easy-to-apply methodology aiming at providing a list of renewable energy sources) (RES) projects capable to reduce green house gas (GHG) emissions, satisfy future energy forecasts and reach the objectives of international/national energy directives and obligations, as, for example, the ones set by the Kyoto Protocol by 2010. The EU project EMERGENCE 2010 developed such a methodology that is implemented here in the case study of wind parks in the Dodecanese islands in Greece. The results obtained consist of a final list of financially viable RES wind projects, for which various barriers have been previously identified and assessed. The additional advantages of the proposed methodology is that besides providing as an end result a comprehensive list of RES projects adopted to specific criteria and regional priorities, it also allows space for involving – from early stages – the local community and stakeholders in the decision-making process (participatory planning); in this way, the EMERGENCE 2010 methodology may assist towards the RES promotion and public acceptance, the profitability of RES investments and the regional sustainable development.     

Monitoring Charge Exchange in P3HT-Nanotube Composites Using Optical and Electrical Characterisation

Charge exchange at the bulk heterojunctions of composites made by mixing single wall nanotubes (SWNTs) and polymers show potential for use in optoelectronic devices such as solar cells and optical sensors. The density/total area of these heterojunctions is expected to increase with increasing SWNT concentration but the efficiency of solar cell peaks at low SWNT concentrations. Most researchers use current–voltage measurements to determine the evolution of the SWNT percolation network and optical absorption measurements to monitor the spectral response of the composites. However, these methods do not provide a detailed account of carrier transport at the concentrations of interest; i.e., near or below the percolation threshold. In this article, we show that capacitance–voltage (C–V) response of (metal)-(oxide)-(semiconducting composite) devices can be used to fill this gap in studying bulk heterojunctions. In an approach where we combine optical absorption methods with C–V measurements we can acquire a unified optoelectronic response from P3HT-SWNT composites. This methodology can become an important tool for optoelectronic device optimization.     

The Lost Value of Groundwater: The Case of Asopos River Basin in Central Greece

Due to the unique nature of the environmental damage, mainly by Cr(VI), the pollution of the Asopos river basin aquifer in Greece has been recently characterized as an ‘environmental crisis’. This paper presents the results of the first attempt in Greece to value the environmental damage to groundwater and to estimate its total economic value using environmental economics. Towards this direction a Contingent Valuation study was conducted, covering the settlements mostly affected in the area. The results indicate that local households are willing to pay an extra monthly charge in voluntary basis for ten years, in order to restore the aquifer under investigation. Different household profiles show different willingness to pay, depending on attitudes against the environmental damage, population age and place of residence. The elicited estimates seem to reflect mostly non-use values and, although smaller than actual private and public expenses for the replacement of the lost public good, the findings are promising and may serve as a spark for future research.