1,721,063 research outputs found
Insights on motor-manual tree felling in Germany, recent developments to ensure efficient operations in singletree selection harvest
No full textApplication of spiroergometry to determine work metabolism related strain in the course of cable work with a mini forestry crawler
No full textEvaluation of a new pruning and tending system for young stands of Douglas fir
No full textIn Germany, management restrictions for Norway spruce ( (L.) H. Karst.) due to climate change lead to increasing interest in Douglas fir ( (Mirb.) Franco) as a potential substituting species. However, Douglas fir requires cost-intensive silvicultural treatments, such as periodic thinnings and, in particular, pruning. In order to improve the efficiency of such treatments, a new tending system with an adapted two-step work system was analyzed. The new system, using electric pruning shears and the backpack clearing saw Husqvarna 535FBX â Spacerâ , was compared to the conventional three-step work system, using handsaw and chainsaw and characterized by tree selection previously conducted as an independent work step. Time and motion studies to determine productivity and costs, as well as ergonomic analysis through heart rate measurements and posture analysis were conducted. Overall, the new system was found to be more productive and to have lower costs, with 8.9 trees per scheduled system hour (4.17 â ¬ tree), compared to the conventional system with 8.1 trees per scheduled system hour (4.44 â ¬ tree). Ergonomic improvements with the new system could be mainly observed during the felling of competing trees, when the level of heart rate reserve was reduced by 9.3 percent points, compared to the conventional system. However, significant advantages in reducing unfavorable body postures expected for the â Spacerâ could not be confirmed. Since time savings within the new system were mainly attributed to the adaptation of workflow and the use of the electric shears during pruning, it should be considered to replace the â Spacerâ within the new system by light chainsaws for best results under the conditions investigated. Picea abies Pseudotsuga menziesii â 1 â 1In Germany, management restrictions for Norway spruce ( (L.) H. Karst.) due to climate change lead to increasing interest in Douglas fir ( (Mirb.) Franco) as a potential substituting species. However, Douglas fir requires cost-intensive silvicultural treatments, such as periodic thinnings and, in particular, pruning. In order to improve the efficiency of such treatments, a new tending system with an adapted two-step work system was analyzed. The new system, using electric pruning shears and the backpack clearing saw Husqvarna 535FBX â Spacerâ , was compared to the conventional three-step work system, using handsaw and chainsaw and characterized by tree selection previously conducted as an independent work step. Time and motion studies to determine productivity and costs, as well as ergonomic analysis through heart rate measurements and posture analysis were conducted. Overall, the new system was found to be more productive and to have lower costs, with 8.9 trees per scheduled system hour (4.17 â ¬ tree), compared to the conventional system with 8.1 trees per scheduled system hour (4.44 â ¬ tree). Ergonomic improvements with the new system could be mainly observed during the felling of competing trees, when the level of heart rate reserve was reduced by 9.3 percent points, compared to the conventional system. However, significant advantages in reducing unfavorable body postures expected for the â Spacerâ could not be confirmed. Since time savings within the new system were mainly attributed to the adaptation of workflow and the use of the electric shears during pruning, it should be considered to replace the â Spacerâ within the new system by light chainsaws for best results under the conditions investigated. Picea abies Pseudotsuga menziesii â 1 â 1Open-Access-Publikationsfonds 202
Adapting Chinese Forest Operations to Socio-Economic Developments: What is the Potential of Plantations for Strengthening Domestic Wood Supply?
No full textOver recent decades, China’s forestry sector went through a transition phase characterized by a management and institutional reform process, with a constant rethinking of the ecological and societal role of forests within a unique political system. Nevertheless, despite impressive achievements in forest restoration and conservation efforts, the enhancement of ecosystem services and forest area expansion through plantation development, China was not able to improve its domestic timber supply capacities according to its demands. Consequently, the continually growing wood processing industry is facing a severe demand-and-supply gap, causing high dependencies on timber imports. Outdated forest operations practices, dominated by manual labour, are not able to meet supply demands or to implement new silvicultural strategies for enhancing forest quality and productivity and are a widely unnoted disruption of a sustainable development. Therefore, this review presents the status quo of China’s forest operations sector, how it is shaped by forest policy reforms and recent socio-economic developments. In addition, suggestions are developed how the sector can progress through policy adaptations in order to develop sustainable timber supply capacities based on a domestic plantation sector
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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