Efficiency of small-scale firewood processing operations in Southern Europe

The study determined the performance of small-scale commercial firewood processing operations under the typicalwork conditions of Southern Europe. In particular, five unitswere tested, fedwith the same 2.1-mlong beech (Fagus sylvatica L.) logs. Allmachineswere testedwith sorted and unsorted logs. Productivity varied between 1.1 and 2.1 t h−1, and cost between 20 and 39 € t−1. There were significant differences between machines, which may partly be attributed to operator effect. Feeding the machines with sorted logs had a significant effect on the productivity of all machines on test, increasing productivity by 40% and reducing cost by 34%. Fuel use varied between 1.3 and 2.8 l t−1. The energy balance was always very favorable. The ration between output and input was never smaller than 59 to 1 and peaked at 130 to 1. In otherwords, processing required about 1% of the energy contained in the firewood — or 1.7% in the worst case. The productivity figures reported in this experiment were much lower than reported for Northern Europe, which seems to confirm the significant effect of regional work conditions – especially different wood species – on firewood processing performance

Trends and Perspectives in the Design of Mobile Wood Chippers

Mobile wood chippers represent a mature technology now available in a wide range of sizes and configurations. Different types exist, but the most widespread are disc and drum chippers. The latter have enjoyed wider popularity in recent years because they are best suited to processing logging residue and other low-quality wood. Drum chippers can be fitted with screens, designed to re-circulate oversize particles. In general, industrial chippers offer high productivity and high fuel efficiency, especially if settings are properly adjusted. Chippers are highmaintenance equipment and require proper care. Maintenance cost increases with machine age and can be predicted quite accurately, and so can chipping productivity and cost. Reliable models exist for estimating both maintenance cost and productivity, based on dedicated userentered assumptions. All things being equal, there are no substantial productivity and maintenance differences between tractor-powered and independent-engine chippers

Effect of Chipper Type, Biomass Type and Blade Wear on Productivity, Fuel Consumption and Product Quality

The study determined the time consumption, fuel consumption and chip size obtained with two different industrial chippers, working with logging residues (tops and branches), thinning material and pulpwood. Specific time consumption per oven dry tons (odt) was 83% higher for the less powerful disc chipper, and chipping forest residues resulted in a 35% increase in specific time consumption compared to chipping thinning material. What is more, the interaction between the two factors pointed at a different suitability of the two machines to chip different materials, since the difference in specific time consumption between the drum and the disc chipper was larger when chipping forest residues rather than thinning. Specific time and fuel consumption of the more powerful drum chipper increased by 30% and 39%, respectively, when working with dull blades compared to working with sharp blades. The best product quality was obtained when applying the disc chipper to pulpwood material. However, the same machine produced more fines when fed with forest residues

The value of privacy: concerns, attitudes, behaviors online, and information protection measures

2012 - 2013Most of our lives takes place on-line. Our on-line activities, affect directly or indirectly the way other people perceive us. One have to careful decide what to expose and what not. There are a lot of personal and sensitive information that people could unintentionally disclose. Indeed an enormous amount of data is being generated and can be disclosed by an increasing number of people on the Web, often without know who is recording what about them. The odds of being tracked without full acknowledge is growing mainly because of two reasons: the exorbitant number of company in the behavioral advertising field and a market overfilled with free services to attract users. This thesis focus on the study of the value of privacy, as intended by people. Learning the value of privacy is of great importance. How people value their own privacy affects the way relationships among individuals are created and maintained. Not only, it have implications on how an individual relates himself with the world, it influences user behaviors and attitudes. The mechanisms responsible for how people value their own privacy are bounded to the perception of risks and perceived level of fairness of the outside world. That component is the awareness. The way an individual perceives the risks around him/her, represent one of the big challenge in order to fully understand the way people value their privacy. A better understand of those mechanisms and an increased awareness will help to design and build privacy by design systems. Increased awareness can help users to understand how and why their privacy is mined, and to become more informed about what silently happens during their navigation. Learning from disclosure of personal information may help to discriminate potential harmful activities from daily and regular activities that can be performed. Awareness could help people to make informed decision about privacy online, and adopt countermeasures if necessary. Protecting users on-line from privacy risks is a difficult task. Task made even more difficult by users’ attitudes. Users are not fully aware of the risks of privacy leaks, even after the increasingly number of press reports about privacy leakage and personal information disclosure on the Web. They ignore that their data can be collected, aggregated and linked with ambient information for various purposes. Anyway, even if awareness is not the only mechanism involved in evaluating privacy, it can be used to study if a privacy tool can help users to make informed decision to reduce their exposure while on the Web. To this aim, we conducted a study to analyze general perceptions, attitudes, and beliefs about privacy online, with a focus on the mutual influence with users skills. We discovered mechanisms responsible for how a person value its own privacy: a) skills influence the perception of privacy risks b) privacy is worth the price if it is a side effect of another well-recognized benefit. [edited by author]XII n.s

The Effect of New Silvicultural Trends on Mental Workload of Harvester Operators

Close-to-nature (CTN) forestry offers many advantages, but makes management more complex and generally results in lower harvesting productivity and higher harvesting cost. While the higher harvesting cost of CTN is widely acknowledged, few ever consider the potential impact on operator workload, as the harvesting task becomes more complex. This study aimed to determine the mental workload of harvester operators under two silvicultural regimes: »pure conifer« stand and »mixwood« stand. In total, 13 harvester operators with varying experience levels were monitored for work performance and mental workload when operating a harvester simulator in two virtual stands designed according to the above-mentioned silvicultural regimes. Mental workload was assessed using the NASA Task Load Index (NASA-TLX) interview method and heart rate variability measurements, during two 30-minute test sessions performed in the »pure conifer« and the »mixwood« stand, respectively. As expected, operating in a more diversified »mixwood« stand resulted in a marked productivity loss, estimated between 40 and 57%. The study also confirmed the increased aggravation of mental demand, effort and frustration experienced by the operators when passing from the »pure conifer« stand to the »mixwood« stand. Such increase in mental workload was independent of the age and experience of the operators. Results can be used to paint a more holistic picture of CTN forestry and its implications for harvester operators. Besides increasing the number of subjects being monitored, future studies should focus on live forest operations

Operational Trials of Cut-To-Length Harvesting of Poplar in a Mixed Wood Stand

Cut-to-length harvesting systems offer an alternative to conventional mechanical systems for thinning mixedwood stands. We evaluated the performance of a single-grip harvester and forwarder in a poplar-dominated mixedwood stand in Southern Ontario to quantify the effect of tree size and tree form on harvester productivity and harvesting cost, and to assess the damage caused by the harvesting operation to advance regeneration and residual trees. A single-tree selection silvicultural system was used. Individual trees were assigned a form index based on their visual estimates of limb size and stem form. The cut-to-length harvester produced 23.1 m3 per productive machine hour (PMH). Forwarder productivity was 17.2 m3/PMH. The results indicate a significant and positive relationship between harvester productivity and tree size (dbh) and tree form. Tree size (dbh) has the greatest influence on the unit cost of harvesting. At an average 27 cm dbh and extraction distance of 200 m, the stump-to-landing cost was approximately 10 US$/m3. As tree size increased, the unit cost of wood produced decreased. Damage to residual trees and advance regeneration was minimal. The results suggest that single-grip cut-to-length harvesting systems can be effective in managing poplar-dominated mixedwood stands

Evaluating Efficiency, Chip Quality and Harvesting Residues of a Chipping Operation with Flail and Chipper in Western Australia

Roadside chipping is a common harvesting system in Australian plantations, which utilizes a mobile chipper stationed at the field edge to produce high-quality pulp chips for export. The studied harvesting system included a feller-buncher, two grapple skidders, a flail-debarker and a disc chipper. The study goals were to determine machine productivity, operation costs, fuel consumption, chip quality and measure the amount of slash left in the field after harvesting. The average productivity for feller buncher and skidder were about 97.26 GMt/PMH0 and 60.22 GMt/PMH0, respectively. The productivity of flail and chipper averaged at 57.80 GMt/ PMH0 and 58.18 GMt/PMH0 in this case study. The transportation productivity averaged about 57.34 GMt/PMH0. Time studies and regression analysis were used to model machine productivity. Tree size had significant impact on the feller-buncher productivity, while skidding distance was a significant variable affecting skidding productivity. Operation costs were evaluated using the ALPACA (Australian logging productivity and cost appraisal) model. This paper offers valuable information about the impact of different factors on feller-buncher and skidder productivity. Application of two skidders resulted in high total operating cost. Extracting whole trees to roadside yielded a very small amount of remaining slash distributed on the site