Substantiating optimum parameters and efficiency of rotary brush cutters

The problem of untimely forest thinning is quite common in today's society. It leads to the emergence of the underbrush, which negatively impacts the growth and development of young trees. Therefore, this work aims to estimate the feasibility of applying a new rotary brush cutter model to eliminate excessive vegetation. The dependence of the tractor's speed when removing underbrush with different diameters of tree trunks was established by performing mathematical modeling to optimize the brush cutter parameters. Three types of flexible inertia cutting devices were investigated: flat knives, sprocket chains, and knife chains. Knife chains are the most optimal choice as they cut plants most efficiently (94.61% and 92.5% for two-year and three-year underbrush, respectively). They also show the lowest energy consumption for underbrush with a trunk between 1 and 2.4 cm in diameter. Further experiments are required to determine if the developed mathematical model can be used for more neglected forestry stands. © 2022 Institut za Istrazivanja. All rights reserved

Improving the efficiency of forest companies by optimizing the key indicators of sustainable forest management: a case study of the Far East

Forest plantations provide a wide range of products. Therefore, it is vital to ensure the sustainable growth and adequate management of forest resources. This study aims to examine the current challenges facing the forest industry, such as the depletion of forest resources, the increasing cost of wood processing products, and intensifying competition in the timber market (caused by the tropical wood supply). These challenges force the world’s leading forest countries to intensify forest cultivation, to consult forest industries in the Far East and to optimize the sustainable use of forest resources. It was found that current distribution of cutting practices threatens the forest ecosystem. The study suggests a scheme where 10–30% of forest area is clear-cut, 70–90% is selectively logged, and 20–35% is exposed to gradual felling. Factors, such as harvesting time, exhaust emissions, the loss of young trees, topsoil degradation, load on the soil surface, and the slope angle are essential for building mathematical models of forest sustainability. The intensity of wood transportation is also a critical factor influencing the above indicators. The study proposes a model for reorganizing regional wood harvesting companies to improve their profitability. The theoretical model is adapted to the Far Eastern context, but is suitable for use in other parts of the world. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group

Modeling the effect of wheeled tractors and skidded timber bunches on forest soil compaction

An increasing demand for forest products incites a large number of log transportation operations, which may lead to negative consequences for the soil and the ecosystem as a whole. This paper is focused on establishing a mathematical model to estimate the soil deformation and compaction processes under tires of wheeled forest machines and individual components of the skidding system such as forwarder, limbs, butts, and tops of tree-lengths in high latitudes, permafrost soil and forests. The method applied is based on simulating the impact processes of elastic tires and the skidding system on the soil through a mathematical device for the measurement of the compaction parameters for different types of soil and the size of the shelterbelt. The effectiveness of the proposed models was evaluated according to experimental results. The influence of the rheological (elastic, viscous, and plastic) properties of soil were studied. The elasticity of tires and the running speed of forest machines can help to control the performance of forest machines. This can be done by reducing the pressure exerted on the soil and increasing the number of skidder passes 1.5-2-fold. Comparative analysis showed that the calculated data differ from the experimental ones by no more than 10%. The obtained results and the developed model will allow for a qualitative and quantitative assessment of technological impact on the soil during the projecting maps for logging operations. © 2021 Institut za Istrazivanja. All rights reserved

Predicting the Passability of Wheeled Tractors

Assessment of the tractor's passability plays an essential role in determining its capability to move under certain conditions. However, the operation of forest machinery may lead to soil deformation and degradation of its mechanical properties. Consequently, this study aims to develop a mathematical model for the tractor's crosscountry capability assessment and its impact on the soil. A predictive model was created as part of the study, which depends on the soil and the forwarder parameters. Some high-correlation dependencies of deformation modulus and cone index, specific tractive force, internal friction angle, and shear modulus on these parameters were established. The developed model can be used to analyze changes in rut depth and soil compaction factors after multiple tractor passages. Soil moisture content and temperature can influence the deformation rate, as drier and warmer soils tend to deform much faster. Furthermore, the proposed model can analyze the impact of forestry and agricultural machinery on soils. © 2022, Mathematical Modelling of Engineering Problems. All Rights Reserved

The Mathematical Model of Forestry Machines Impact on Cryolitozone Forest Soils

In the Russian Federation, the permafrost zone are gaining increasing importance due to wood procurement operations. Active timber harvesting, accompanied by the simultaneous development of wood processing enterprises in the Far Eastern Federal District, leads to the depletion of available and exploitable forests in southern and central Siberia, Buryatia, and Khabarovsk territory. The exploitation of modern forestry machines, wheeled forwarders, in particular, broadens the question of their effectiveness. In specific production and geotechnical conditions, the cross-country ability and technological productivity of wheeled forwarders are of particular relevance. These circumstances, combined with the need to minimise technological pressure on the ecological environment raise the problem of optimisation of the forest machines. We developed a mathematical model for calculating parameters of the defrosting soil destruction process occurring at the border with the permafrost zone. The mathematical model allows assessment of the possible value depth of the induced track at the stage of the project design. The assessment is conducted with the account of the forest machine's technical and maneuvering capabilities in specific natural and industrial conditions. © 2020 - IOS Press and the authors. All rights reserved

Modeling of the processes of the modification of the current volume warming by drainage and pressing

This work creates and verifies a mathematical model for modifying soft-leaved wood by impregnation and compaction. The relevance of this work is because due to global climate change, recently there has been a change in the average formula of the species composition of many forests of the temperate zone of Eurasia: soft-leaved wood species replace the coniferous forests of natural generation. The change in species composition is aggravated by the active spread of plantation growing of forests, because soft-leaved wood species are more suitable for plantation growing. One of the most promising areas for processing soft-leaved wood, including those grown by plantation, is the modification of such wood by impregnation and compaction. The main technological processes of obtaining modified wood with the achievement of specified parameters and properties is the dehydration of samples impregnated with various compositions with simultaneous pressing and drying. As a result of the implementation of the developed mathematical model, an equation of linear multiple regression is obtained depending on the sample processing time on the required values of their compaction and humidity in a given temperature field, which forms a reliable theoretical basis for solving various optimization problems of the technological parameters of the pressing and dewatering plasticized wood samples. © 2019, Agricultural Academy, Bulgaria. All rights reserved