Resources and Technology

To implement an economically profitable initial and main timber rafting in raft units, the development of modern flat-raft units with high transport and operational performance is required. A highly efficient flat raft unit with a simple design and a high coefficient of raft section density is considered. The above advantages of a flat raft unit are formed due to the specific design of round timber laying in the rows of a flat unit, when each round timber of the upper row is stacked between two round timbers of the lower row with internal and external transverse gaskets. The use of the considered highly efficient flat-flow unit, regardless of its operating conditions, necessarily requires the correct calculation of its overall dimensions. The method to substantiate geometric parameters of the developed flat raft unit is proposed, where the emphasis is placed on determining the design and actual length, width and height of the raft unit. The geometric parameters of the flat raft unit were justified by taking into account the design features of the raft unit, the design of round timber laying in rows, the minimum width and depth of the floating road. The obtained dependences for calculating the design width, length and height of a flat raft unit allow the authors to determine the maximum possible overall dimensions of a flat unit. In turn, the obtained dependences for calculating the actual length, width and height of a flat raft unit are working formulas that take into account the maximum possible laying of round timber in a row and the number of stacked rows, and are used in calculating the overall dimensions of the manufactured flat raft unit for specific navigation conditions. The use of the proposed highly efficient flat-flow unit for the initial and main timber rafting will make it possible to ensure cost-effective delivery of wood to consumers from hard-to-reach places that lack a developed network of roads and railways.

More strict environmental performance requirements for fuels and power plants in recent decades have led to a large-scale search for new, cost-effective, environmentally friendly energy carriers. The increased demand for energy carriers has heightened interest in alternative sources of fuels including hydrogen to be used for electricity generation and in transportation business. The article discusses and analyzes the issues of production and use of hydrogen, which is currently considered a priority and promising energy carrier in many regions of the world. The main ways and technologies for producing hydrogen, its most important physical and chemical properties, operational and environmental characteristics are considered. It can be assumed that hydrogen and hydrogen energy may gain an impetus for wide commercialization under favorable economic conditions and compete with fossil fuels in certain regions of Europe and the world. The potential benefits from expanding the use of hydrogen and the development of hydrogen economy are seen primarily in healing the environment and enhancing the energy security of a number of regions and countries. It can be expected that future technological advances will promote the mid-term hydrogen competitiveness. Currently, European countries are considering increasing hydrogen production as a way to reduce dependence on Russian oil and gas import, as well as to reduce greenhouse gas emissions. Keywords: hydrogen; fuel cell; hydrogen energy

In the development of wooden house construction, it is very important to use environmentally friendly materials with economic and technical characteristics that satisfy both the housebuilder’s and tenant’s needs. Recently more attention has been paid to wood panels, which in many respects surpass their counterparts. When using wooden panels of various designs their characteristics are very important, one of the most important of which is sound insulation. During the patent search, inventions were found to determine the sound insulation of materials, but they are not aimed at determining the sound insulation of panels or are intended for large-sized panels, which makes it difficult to use them in laboratory conditions. The article is focused on the installation design to determine the sound insulation of wooden panels (wood slabs) from the air noise. The proposed installation consists of acoustic sound-proofing chambers of high and low pressure levels allowing the installation to be used in ambient noise conditions up to 75 dB and to place a 327x327 mm test panel between them (the active test area with a diameter of 315 mm). The proposed design makes it possible to study samples up to 150 mm thick, both single- and multi-layered ones. Panels made from foam, polyurethane foam, three-layer plywood, isover whose sound insulation properties are known were used as test samples. When comparing the obtained results with the known sound insulation characteristics of these materials the deviation was no more than 8%. which confirms the operability of the installation. The tests were also performed on three-layer wood panels assembled from a pine furniture board with a thickness of 18 mm. The proposed installation characteristics comply with the interstate standard GOST 27296-2012 "Buildings and structures. Methods for measuring sound insulation of enclosing structures". This installation can be effectively used to determine the sound insulation of various panels, including wooden ones. This will allow us to determine the possibilities of their application in various conditions of wooden house construction.

Currently, the interest deepens in the differentiated use of planting material characterized by different biometric characteristics in order to increase its survivability when planting on a cultural area. To develop programs for growing planting material under the specified conditions of the cultural area, a database should be created to identify the influence of different sets of factors on the habitus and vitality of seedlings. Prerequisites for its creation arise in the absence of control and compliance with the growing seedlings technological schemes recommended for specific forest-growing areas. For example, a fallow field is introduced into nursery rotation only in 80 % of field permanent nurseries surveyed in the Northwest. The aim of the study was to assess the effect of fallow in nursery rotation on the quality of seedlings. Two-year-old pine and spruce seedlings were evaluated in a field permanent nursery of the Baltic-Belozersky forest district where a traditional work performance technology is applied. Unless fallow was included in the technological scheme of growing, a low yield of seedlings was noted. The density of seedlings was 3.4 times less compared to the fallow field. The inclusion of fallow fields in nursery rotations allowed shortening the period of growing seedlings, especially those of pine. The number of seedlings that reached the standard size in the second year of development on a fallow field increased by 76 % in pine and by 30 % in spruce. The fallowing of fields contributed to the greater development of the aboveground part of seedlings in both pine and spruce. So the mass of the aboveground part of the pine increased by 65 % and of the spruce — by 125 %. This worsened the ratio of the mass of thin roots and the aboveground part of pine seedlings. Seedlings grown in fields without fallowing and characterized by the low degree of hardiness and the ratio of the length of the aboveground and underground parts when they reach the standard sizes can be recommended for planting in arid conditions.