1,720,994 research outputs found
Influence of Saturated Organic Matter on the Accuracy of In-Situ Measurements Recorded with a Nuclear Moisture and Density Gauge
Full text linkThe impact of machines on forest soils is regularly assessed and quantified using absolute bulk density, which is most frequently obtained by soil cores. However, to allow for repeated measurements at the exact same locations, non-destructive devices are increasingly being used to determine soil bulk density and moisture content in field studies. An example of such a device is a nuclear moisture and density gauge (NMDG), originally designed as a control measurement for soil bulk density and moisture content in geotechnical applications. Unlike road construction or foundation projects that use mineral soil or gravel, forest soils have complex structures and the presence of organic matter, which can skew moisture and density readings from a NMDG. To gain further knowledge in this respect, we performed controlled tests in a sandbox to quantify the influence of varying amounts of saturated organic matter (3, 5, 10, and 15%) mixed with mineral soil in different layers (0–5, 0–10, 0–20 and 0–40 cm) on the accuracy of soil moisture content obtained by a NMDG and soil theta probe at varying depths. Main results illustrated that the presence of saturated organic matter per se was not problematic but moisture content overestimations and related underestimation of dry bulk density occurred when the tested measurement depth was below the created organic layer. Since forest soils often exhibit higher organic matter contents in the upper horizon, correction factors are suggested to minimize the moisture content variations between NMDG and reference method. With the use of correction factors, NMDG can present a non-destructive, fast, and accurate method of measuring soil moisture and bulk density in forestry applications
The role of brush mats in mitigating machine-induced soil disturbances: an assessment using absolute and relative soil bulk density and penetration resistance
No full textSoil displacement during ground-based mechanized forest operations using mixed-wood brush mats
No full textEffect of Season and Machine Type on Performance of Semi- and Fully Mechanized Harvesting Systems in Beech-Dominated Stands
Full text linkIt is common to have large trees in mature hardwood-dominated stands. This is especially true for European beech (Fagussylvatica L.), which can also have a complex architecture. Such trees have predominantly been harvested using motor-manual operations. However, in an effort to increase occupational safety and allow for a more continuous wood flow to processing facilities, fully-mechanized systems are also being employed more frequently. This study was established to determine the effect of season (Fall or Winter) and harvester type (wheeled or tracked) on the performance of semi- and fully- mechanized harvesting systems deployed in beech-dominated stands. Time-and-motion analysis was conducted on a total of 927 trees located in two forest sites in Germany. The study indicated that new silvicultural prescriptions make it impossible to harvest all trees exclusively with mechanized systems, even in the case of the tracked harvester with its 14.5 m boom. Motor-manual intervention was needed with trees that were too large, malformed or out of reach. Motor-manual intervention was significantly more frequent for the wheeled (30%) than for the tracked harvester (18%). Once again, tree size had the strongest effect on time consumption in a linear model, which varied from 0.5 to over 6 min per tree. Season and machine effect were also significant but could only account for a small fraction of the total variability. For the same tree size, time consumption was higher with the wheeled harvester and during the fall. The model also indicated a significant relationship between tree form and time consumption, even though the explanatory contribution of this independent variable was relatively small, too. Good stem form resulted in a lower time consumption. The larger tracked harvester was generally more efficient, but also more expensive to own and operate: its higher costs must be weighed against the higher revenues. New silvicultural trends make it difficult to achieve full mechanization, but the results of this study may guide managers towards technical solutions that minimize motor-manual intervention to the advantage of higher productivity and better occupational safety
Skyline tension and dynamic loading for cable yarding comparing conventional single-hitch versus horizontal double-hitch suspension carriages
Full text linkWire rope used in cable logging, where a series of cables facilitate the extraction of timber on steep terrain, experiences high tensions that must be managed to ensure safety. Innovations change practices over time and double-hitch carriages, which allow trees to be extracted horizontally, are a recent example. This makes it feasible to harvest across terrain with limited deflection, increases the recovery of biomass, and potentially reduces high-dynamic load events associated with ground contact. In this study, a standard single-hitch carriage was compared against a new double-hitch carriage under controlled conditions. Tension was measured continuously and specific elements, such as tension when the carriage was at midspan, maximum tension at breakout and inhaul, and magnitude of cyclic tension during inhaul were identified, measured and compared against payload. While payload was similar in the treatments, the additional weight of the double-hitch carriage resulted in higher skyline tensions. In both treatments, payload and skyline tension when the carriage was at midspan were strongly correlated. Cyclic tension was reduced by the double-hitch carriage system. While a number of unique high-dynamic loads were identified that were not part of the normal extraction, they represented only 6% of the cycles and the maximum tension was similar to that experienced during break-out and inhaul. This study increased the understanding of skyline tension during logging operations and the effect of carriage type. It showed that, though tension often exceeds the safe working load of the cable, it does not exceed the endurance limit for a well-designed and operated system
Integration of Harvester Production Data in German Wood Supply Chains: Legal, Social and Economic Requirements
No full textDigitalization and its associated technology are shaping the world economy and society. Data collection, data exchange, and connection throughout the wood supply chain have become increasingly important. There exist many technologies for the implementation of Industry 4.0 applications in forestry. For example, the integration of harvester production data throughout the wood supply chain seems to have strong optimization potential but it is faced with several challenges due to the high number of stakeholders involved. Therefore, the objective of this article is to analyze the legal, social, and economic conditions surrounding the integration of harvester production data integration in Germany. For analysis of the legal and economic conditions, a narrative literature analysis was performed with special consideration of the relevant German and European legal references. For determination of the social conditions, a qualitative content analysis of 27 expert interviews was performed. Results showed that legal ownership of harvester production data cannot be clearly defined in Germany, but there exist several protection rights against misuse, which can define an ownership-similar data sovereignty. Furthermore, harvester data use can be restricted in the case where personal data are traceable, based on European data protection law. From a social perspective, the stakeholders interviewed in the study had different opinions on data ownership. Stakeholders require specific criteria on the data (interfaces) and other factors for the acceptance of new structures to allow successful harvester data integration. From an economic perspective, harvester production data are tradeable through varying transaction forms but, generally, there is no accepted and valid formula in existence for calculating the value or price of harvester data. Therefore, the authors advise discussing these issues with key stakeholders to negotiate and agree on data ownership and use in order to find a suitable solution to realize optimization potentials in the German wood supply chain
Estimation de la matière ligneuse marchande non utilisée à l'aide de données provenant d'ordinateurs de bord d'abatteuse-façonneuse à tête multifonctionnelle
No full textLe régime forestier du Québec aspire à un aménagement forestier durable sur les terres publiques. De ce fait, une entente entre le gouvernement et l'industrie forestière pratiquant des activités d'aménagement forestier a été prise concernant le bois marchand laissé sur le parterre de coupe, s'appelant Matière Ligneuse Non Utilisée (MLNU). Cette entente vient avec l'obligation d'effectuer un inventaire terrain, considéré comme particulièrement coûteux par l'industrie forestière. En plus du coût élevé de l'inventaire, la pénurie de main-d'œuvre pour ce type d'inventaire technique ne permet pas de maintenir la fréquence requise demandée par le ministère, entraînant une diminution de la précision de la quantification de la matière ligneuse non utilisée. Considérant l'important manque de main-d'œuvre, particulièrement dans la région de la Gaspésie, et des marges de profit généralement faible des compagnies privées, l'objectif général de la recherche est d'estimer le volume de MLNU laissé à la suite des opérations de récolte mécanisée en bois tronçonnés à l'aide des données des ordinateurs de bord (ODB) des abatteuses-façonneuses à tête multifonctionnelle pour réduire le coût associé à l'inventaire conventionnel et pallier au manque de main-d'œuvre. Cinq sites ont été sélectionnés et récoltés par cinq différentes abatteuses-façonneuses munies d'une tête multifonctionnelle différente. La sélection des têtes multifonctionnelles a été faite en évaluant la proportion de chaque marque, suivant un sondage effectué chez les entrepreneurs en Gaspésie. Trois têtes Ponsse avec le système d'information OPTI4G, et deux têtes LogMax, l'une sous le système Log Mate 500 et l'autre Log Mate 510, ont été sélectionnées. Trois inventaires distincts ont été effectués : (1) inventaire avant coupe de caractérisations du peuplement forestier; (2) inventaire avant coupe des arbres études; et (3) inventaire après coupe des produits et de la matière ligneuse non utilisée des arbres études. La reconstruction de 970 arbres études (460 épinettes blanches et 510 sapins baumiers) a été effectuée pour en premier lieu développer les algorithmes de volume nécessaires pour évaluer la section au-delà des produits tronçonnés par l'abatteuse-façonneuse, soit la tête de l'arbre, jusqu'à un diamètre de 9,1 cm (diamètre minimum marchand). En combinant le modèle de Varjo et une régression linéaire, il a été possible d'estimer la longueur de la section supérieure par arbre pour l'épinette blanche et le sapin baumier. Un biais de prédiction de 0.0245 m et 0.1748 m a été évalué respectivement la section marchande de la tête pour l'épinette blanche et le sapin baumier. Un outil de spatialisation utilisant les rapports de production de StanForD (.pri) et StanForD 2010 (.hpr), les données de GPS ainsi que le contour des secteurs de coupe, a été développé pour permettre la localisation du volume de MLNU par secteur de coupe. Les fichiers de production .pri (StanForD) n'ont pas d'information d'horodatage (timestamp), contrairement aux fichiers de production .hpr. Ainsi, lorsque l'outil utilise un fichier .pri, le volume de MLNU est évalué à l'hectare pour l'ensemble d'un secteur de coupe, alors qu'avec le fichier .hpr, il est possible de localiser par tige le volume de matière ligneuse et ensuite, une sommation par hectare est effectuée, en regroupant chaque tige située à l'intérieur d'un quadrillé de 100 m x 100 m, obtenant ainsi une spatialisation plus précise de la MLNU. Finalement, une comparaison exploratoire de la méthode de l'inventaire MLNU traditionnel et de la méthode avec les données d'ODB a mis en évidence l'opportunité d'économies de coûts (environ 36,80 $/ha) liée à l'utilisation des données OBD pour estimer la MLNU, tout en permettant un temps de réponse plus rapide pour apporter des corrections en ciblant les zones problématiques. De plus, l'utilisation d'un tel outil pourrait permettre de réduire le temps de déplacement en forêt des techniciens forestiers et ainsi, prévenir des accidents de travail courants
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
- …
