Studies of aspen and birch wood interaction with pulsed exposure to microwave energy have been carried out. A method for determining the effect of microwave energy on the temperature inside the test specimen has been developed. It includes experimental setup for studying heat and mass transfer during drying and heat treatment of wood with microwave energy. Moisture content inside wood specimens has been determined by a new method using a laboratory installation for studying the mechanical properties of wood under the influence of microwave energy. This energy influences on the drying speed of the tested wood specimens. The research enables to select the optimal mode of wood heating by pulsed exposure to microwave energy. The results of wood tests for strength and hardness, obtained under the influence of microwave energy, have revealed the effect of wood hardening. The research has shown that microwave treatment of specimens reduces drying time of aspen and birch wood by five times in comparison with convective treatment.

One of the main difficulties in combating forest fires with conventional water-based methods is the difficult topography and the fact that there are usually no accessible roads to bring firefighting techniques closer to the fire site. Today, a large number of scientific teams are working on the topic of extinguishing the edge of a forest fire with soil. The aim of the study is to increase the efficiency of forest fire prevention and extinguishing by ground-throwing machines by removing the upper combustible layer of forest soil, the formation of a loosened soil shaft from the mineralized layers of forest soil and throwing soil into the edge of a forest ground fire. The paper briefly describes the technical means for extinguishing forest fires using soil. The analysis of the structures of soil-throwing machines has been carried out. The promising directions for improving the technology and working bodies of fire-fighting ground launchers are described, the advantages and disadvantages of its designs are revealed, and ways of further improvement are outlined. A promising design of a strip-laying soil gun with a hydraulic drive of working bodies for preventing and extinguishing forest fires is presented. A distinctive feature of the developed design of the strip-laying soil launcher is the use of an auger to remove the upper fire-hazardous cover, consisting of plant residues, and cut spherical discs to improve the quality of loosening the soil shaft. As a result of the conducted studies of the working process of the strip-laying machine, it was found that the share of the soil covers with combustible materials in the soil flow decreased from 40 to 7%, and the quality of soil shaft loosening increased by 17%, due to which the average distance of soil ejection increased from 10 to 15 m and the power consumption of the rotor-thrower is reduced from 12 to 10 kW.

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The paper provides an overview of the research of the working processes of the screw working bodies of technological machines. It is shown that at present such an issue in the theory of auger working bodies as the number of auger turns is necessary, what position of the auger spiral should be in relation to the center, etc. is not completely solved, the solution of these issues can provide increased productivity. In modern conditions, caused by global climatic changes in the world, the requirements for the conditions for the protection of forest zones have increased, which makes it necessary to increase funds for fighting fire in forests and increase the raw material and financial base of specialized forest protection services, which is due to the constant search for new and improvement of old methods of forest fire elimination. Special ground-throwing machines have the greatest efficiency, but they do not have working equipment for pushing combustible materials in the form of a ground cover, dead wood, and felling residues. For these purposes, in our opinion, the most suitable auger working bodies installed in front of the rotor-throwers. Modeling of the working process of screw working bodies is based on the particle dynamics method. In the process of modeling, the forest litter is made in the form of a set (about 5000) spherical elements in diameter, which interact with each other and with the working surfaces of the auger working bodies. The working surfaces of the screw drum are represented from the lateral surface of the cylinder, modeled as a separate geometric figure, and 200 triangles forming a helical surface. It was found that the optimal cutting depth is 8-10 cm, at which the auger almost completely cleans the working strip from the soil layer, but at the same time is not too deeply buried to cause large power losses. The identified main parameters of the auger working bodies will be used to create an effective forest fire ground-throwing machine.

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