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Lykidis C.,Institute of Mediterranean Forest Ecosystems and Forest Products Technology | Nikolakakos M.,Technological Educational Institute of Athens | Sakellariou E.,Technological Educational Institute of Athens | Birbilis D.,Technological Educational Institute of Athens
Materials and Structures/Materiaux et Constructions | Year: 2016

Purpose of this study was to assess a modification to the hardness determination method in order to mitigate the effect of visual measurements on the consistency of Brinell method and accuracy of the results. The amendment has been previously proposed by other researchers and refers to the automated determination of indentation diameter and relies on the ability of modern testing machines to accurately measure indentation depth, through which the calculation of indentation diameter is possible. From the results of this study it was shown that the hardness values acquired by the proposed modification presented statistically significant difference compared to those acquired using the visual method described in EN1534 (Wood and parquet flooring—determination of resistance to indentation (Brinell)—test method, 2000). Moreover, compared to the standard methodology, the application of the proposed amendment led to hardness values which are better correlated to density as well as Janka hardness for the six different solid wood species tested. Furthermore, the proposed modification resulted to hardness values which seem to be less affected by the presence of varnish coatings. © 2015, RILEM. Source

Willems W.,FirmoLin Technologies BV | Willems W.,University of Gottingen | Lykidis C.,Institute of Mediterranean Forest Ecosystems and Forest Products Technology | Altgen M.,University of Gottingen | Clauder L.,Eberswalde University Of Applied Sciences
Holzforschung | Year: 2015

Thermally modified wood (TMW) is currently produced commercially by a range of processes across many countries. A prerequisite of the commercial success is an efficient quality control (QC), and methods with this regard are discussed in this review. When direct measurement of the key attribute of the material is not feasible, QC is based on a suitably chosen physical or chemical "marker". A critical evaluation of currently applied markers reveals that most of them only provide data for comparative purposes for a particular species and/or over a narrow process range. Such markers do not allow making an objective judgment of quality, which is independent of process information or reference samples provided by the manufacturer. On the other hand, they can be very useful for monitoring product variability in the TMW factory and wood during the heat treatment. Recommendations for future development are the general validation of (combinations of) known TMW markers for different wood species and processes, resulting in (1) a reliable and fast laboratory QC method for given samples of unknown origin, (2) a simple and fast indicative QC test for end users, and (3) in-line product markers for feedback-controlled production. © 2015 by De Gruyter. Source

Karma S.,National Technical University of Athens | Zorba E.,National Technical University of Athens | Pallis G.C.,National Technical University of Athens | Statheropoulos G.,National Technical University of Athens | And 7 more authors.
International Journal of Disaster Risk Reduction | Year: 2015

Search and Rescue (SaR) in forest fires is usually applied in a broad area, under foggy or smoky conditions. It mostly involves location of entrapped fire crew or people in between fire fronts, as well as, safely removing them away from the dangerous zone. Moreover, SaR is applied in evacuation of rural residential areas due to heavy smoke impacts, or fire front approaching. Experiences achieved during a field trial, in which unmanned aerial and ground vehicles were deployed and used in a simulated forest fire SaR scenario, are presented. For planning and running the field trial a number of parameters were taken into consideration; logistics, safety plan, contingency plan, different agencies cooperation, time frames and ethical issues. Advantages of using unmanned aerial and ground vehicles in SaR operations include capability of planning and monitoring the operations, integration with the manned resources, connectivity with command and control centers, as well as, coordination of the different unmanned aerial and ground vehicles' platforms. Significant increase of personnel safety is possible through the capabilities of air quality monitoring and search over dangerous areas. Current limitations include limited heat resistance of vehicles and limited flying capability in strong winds and turbulence. Failure of communications is also possible due to rough terrain (autonomy limitations). Against all the limitations, a number of unmanned vehicles already exist that can be adapted successfully for SaR operations in forest fires. © 2015 Elsevier Ltd. Source

Koutsias N.,University of Ioannina | Xanthopoulos G.,Institute of Mediterranean Forest Ecosystems and Forest Products Technology | Founda D.,Institute for Environmental Research and Sustainable Development | Xystrakis F.,University of Ioannina | And 4 more authors.
International Journal of Wildland Fire | Year: 2013

Historical fire records and meteorological observations, spanning more than 1 century (1894-2010), were gathered and assembled in a database, to provide long-term fire-weather associations. We investigated the relationships between forest fire activity and meteorological parameters and sought to find temporal patterns and trends in these historical records and to identify any linkages between meteorological parameters and fire occurrence in the eastern Mediterranean region. Trend analysis of the time series revealed a statistically significant increase in the number of fires and air temperature, particularly after the mid-1970s. Fire occurrence, expressed as the annual number of fires and total burnt area, was strongly correlated with the mean maximum and the absolute maximum air temperature which, in turn, was related to the occurrence of summer heat waves. Total burnt area was also strongly negatively correlated with fire-season precipitation, and positively correlated with 2-year-lagged annual and summer precipitation, underlying the effect of precipitation in controlling fuel production and moisture. These findings support the argument that although annually lagged precipitation totals may have a marginal effect on fire risk by influencing biomass production and accumulation, the lag0 weather parameters are the main drivers of fire spread by directly controlling fuel moisture. © 2013 IAWF. Source

Daskalakou E.N.,Institute of Mediterranean Forest Ecosystems and Forest Products Technology | Albanis K.,Institute of Mediterranean Forest Ecosystems and Forest Products Technology | Skouteri A.,Institute of Mediterranean Forest Ecosystems and Forest Products Technology | Thanos C.A.,National and Kapodistrian University of Athens
New Forests | Year: 2014

A regeneration predictor (RP) has been elaborated to forecast the minimal inter-fire period, required for full recovery (assumed at 1,000 mature stems ha-1, a typical value for a dense pine forest) of an even-aged, postfire regenerating Pinus halepensis population after a subsequent wildfire, in the future. The study has been conducted in three Aleppo pine forests of northern Euboea Island, Greece. Postfire field surveys of sapling growth, sapling density and reproductive dynamics (cone-bearing population fraction, annual cone and seed production per sapling, canopy seed bank build-up) were carried out for three, consecutive growing seasons (years). Additional postfire parameters, with values estimated from literature data, have been also included in order to devise the RP. In the cases of the three populations studied, the application of this RP provides time-windows for full recovery after a recurrent fire, as short as 10-15, 8-11 and 7-11 years, respectively (values corresponding to best and worst scenarios). It is suggested that in even-aged, postfire regenerating Aleppo pine populations, the minimal inter-fire period required for full recovery can be predicted by monitoring a few selected variables, namely (a) sapling density, (b) vegetative to reproductive shift dynamics, and (c) cones/sapling and germinable seeds/cone, for at least 2 years (either consecutive or 2-3 years apart) at a postfire age of 7-12 years. © 2013 Springer Science+Business Media Dordrecht. Source

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