Chainsaw vibrations, a useful parameter for the automatic tree volume estimations and production assessment of felling operations

An innovative approach for the automatic operational monitoring of motor-manual felling activities with chainsaw is here described and discussed. This new system of assessment can be considered as a solution for Precision Forestry (PF) applications and can be employed as a ICT tool for the management of the forest companies. Aim of the proposed system is to manage operational information such as: a) positioning of each felling operation inside the forest, b) measurement of the time spent to carry out the felling, c) estimation of the size of every felled tree, and in the end, d) the analysis of the productivity of the felling operations. This experience is based on the operative principle which considers that the lumberjack, during the actual cutting, drives the chainsaw with the engine at the highest number of rpm. During this action, the generated vibrations reach the maximum amplitude. Some preliminary experiments were conducted during thinning operations in a spruce stand (Picea abies), where a dedicated device composed by a triaxle accelerometer (sampling frequency of 10Hz) and a GNSS module were installed on the filter cover of a professional chainsaw (Husqvarna 560 XP). During the test, for each cut, the duration of the vibration with the maximum amplitude and the section cut area were measured and collected, with the assumption that a strong positive correlation exists between these two parameters. The test objectives were to validate such a correlation and to provide a methodology to estimate the volume of each cut plant. To this aim, once entered the diameter of each plant (derived from the estimated section), the volume for each felled tree was estimated through a specific single entry table commonly used by forestry manager. During two consecutive days of thinning operations, 30 trees were felled and monitored and all the operative parameters through the proposed automatic system were recorded. Simultaneously, a manual time study and diameter measurement using respectively watch and calliper, were performed. 20 of these records were used to create a mathematical model for the volume estimation, while the other 10 were used for its validation. Comparing the results obtained by the automatic time study with those from the manual survey, and with the identification of the felling location, very good correlation values were obtained (R2 >0.75). Beside this, a difference lower than 5% resulted by the comparison between the estimation volume carried out through the new approach and the classic one

Italy-Austria GIL in the new planned railway galleries Fortezza-Innsbruck under Brenner Pass

The paper deals with the possibility of installing a double-circuit Gas Insulated transmission Line (GIL) in the pilot tunnel of the new planned railway galleries Fortezza-Innsbruck. The high GIL power ratings with very low power losses would allow a strong and highly efficient energy exchange particularly useful for the future European Market and could represent a new fundamental step in reconstructing the European interconnection network. Two separate railway tunnels (\u3a6 48 9,6 m) will run under the Brenner Pass from Fortezza (Italy) to Innsbruck (Austria) but will be preceded by the construction of a continuous pilot tunnel (\u3a6 48 4,3 m) useful for work logistics and chiefly for detection of the rock stratigraphy. Once the whole work will be over, the pilot tunnel will be used as a service gallery (drainage of water) where a double-circuit GIL can be efficiently installed. The paper gives the main characteristics of planned galleries, several details on the transmission line and its performance, the electro-magnetic field impact considering the proximity effects and the earthing arrangement in order to zero the touch-voltages in case of phase-to-enclosure short-circuit. The chief features of GIL solution are the lowest transmission power losses and the absence of shunt reactive compensation for this line length (appr. 65 km) but mostly the safety of personnel in case of short-circuit and the possibility of usual re-closure cycles for operation continuity. This paper gives an overview of other analysis: GIL no-load regime, electromagnetic interferences between railway and GIL system, pilot tunnel ventilation and GIL thermal regime. In order to achieve satisfying power flows, the new link requires both Italian/Austrian regional grids (380 kV\uf7110 kV) to be restructured and rationalised. This research is supported by European Community in the framework of TEN-ENERGY programme for analysing both, technical and environmental issues of integrating 380 kV Gas Insulated transmission Line and Rail Transport in tunnel between Italy and Austria entitled "Studies for a new 380 kV transmission line between Italy and Austria through the Brenner pass: Integration of Electricity and Rail Transport in Tunnel". The project leader is TERNA (Italian TSO) whereas the associated beneficiaries are the University of Padova and TIWAG-Netz AG (Tyrol TSO) with support of Graz University of Technology

Diet of the Eurasian otter ( Lutra lutra

Prey preference and seasonal variation in the diet of the Eurasian otter, Lutra lutra (Linnaeus, 1758), were examined by the analysis of 789 spraint samples collected along a 10-km section of a small lowland salmonid river in Serbia, with a trout farm situated in its lower part, from June 2009 to March 2012. Of particular interest was any possible impact of the otter on brown trout, which is important to investigate for preventing and managing any potential conflicts with fishers and fish farmers. Fish were by far the most important otter prey, followed by crayfish. Cottus gobio Linnaeus, 1758 (the European bullhead) was the most common prey species, probably because of the combination of its abundance and easy catchability. Other prey contributed very little to the diet of the otters. Of 11 fish species present in the river, five were found in the otter diet: the European bullhead, Salmo trutta Linnaeus, 1758 (brown trout), Squalius cephalus (Linnaeus, 1758) (chub), Barbus balcanicus Kotlik, Tsigenopoulos, Rab & Berrebi, 2002 (the Danube barbel), and Phoxinus phoxinus (Linnaeus, 1758) (the Eurasian minnow). The bullhead was the only positively selected species, however. The share of fish prey in the otter diet was stable throughout the year, except for a decrease noticed during the summer. The results suggest that otters on the River Gradac target smaller, sedentary, and less nutritious prey. Owing to a small percentage of brown trout in otter spraints, we surmise that otters do not represent a major biological or economic threat, either to the native trout population in the river or to the trout from the nearby fish farm. Although there are no reports of otters causing damage to the trout population in the local fish farm, it is advisable to establish mechanisms for the compensation of fish farmers in case such damage does occur. The data presented in this paper can be used to contribute to the conservation of the otter in stream habitats, especially because there are no published studies on the dietary requirements of otter in Serbia