DEPENDENCE OF GERMINATION OF SEEDS OF FODDER CROPS ON THE DURATION OF STORAGE IN A GAS ENVIRONMENT

The research was carried out in the laboratory conditions of the Federal Williams Research Center of Forage Production and Agroecology on the seed material of nineteen varieties of the selection of VIC, stored since 1986 in a gas environment. The viability of the seeds was determined after 33 years of storage. The laboratory germination rate of the samples after storage varied from 0.7 to 90.3%. Aging of cereal grasses is faster. After storage in a gas environment for 33 years germination of more than 80% was observed in four samples of the legume family and one of the cereals. After being removed from the CSG and placed in normal conditions for a year, most of the samples retained their economic validity, with the exception of forage cereals: brome grass, meadow and reed fescue, and cocksfoot.

Stroboscopic operando spectroscopy of the dynamics in heterogeneous catalysis by event-averaging

Heterogeneous catalyst surfaces are dynamic entities that respond rapidly to changes in their local gas environment, and the dynamics of the response is a decisive factor for the catalysts’ action and activity. Few probes are able to map catalyst structure and local gas environment simultaneously under reaction conditions at the timescales of the dynamic changes. Here we use the CO oxidation reaction and a Pd(100) model catalyst to demonstrate how such studies can be performed by time-resolved ambient pressure photoelectron spectroscopy. Central elements of the method are cyclic gas pulsing and software-based event-averaging by image recognition of spectral features. A key finding is that at 3.2 mbar total pressure a metallic, predominantly CO-covered metallic surface turns highly active for a few seconds once the O2:CO ratio becomes high enough to lift the CO poisoning effect before mass transport limitations triggers formation of a √5 oxide.

Calculation of the main parameters of the ultrasonic oscillatory system for the intensification of gas nitriding processes

The paper studies the matters of designing an ultrasonic oscillatory system taking into account the peculiarities of the impact on the gas environment. Calculations of the elements of an ultrasonic oscillatory system are presented. The types of membrane emitters for influencing the saturating medium during gas nitriding are analyzed.

Computer Modeling and Calculation of the Ventilation Systems for Workplaces and Premises of Electric Welding Production

The most important means of protecting the labor of electric welders is local exhaust ventilation, if required supplemented by general exchange ventilation of electric welding rooms, which contributes to maintaining the normalized state of the air environment. In real conditions, the dust-gas environment of the welding station is influenced by a combination of factors such as the location of welders breathing zone, the relative location of the welding point, and the suction opening of the exhaust device, and the air mobility associated with the aerodynamic interaction of the supply and exhaust devices. The desire to reduce the productivity and energy consumption of exhaust devices usually leads to a change in their effect on the state of the air environment. Therefore, along with the design features of the air extract, it is of great importance that the designs of the exhaust devices correspond to the nature of the welding work performed, as well as the space-planning solution for the mutual arrangement of welding posts and supply and exhaust devices, especially in the rooms with a limited volume. The article is devoted to the analysis of the effect of these factors on the dust and gas environment of the electric welding stations, and the search for their rational combination by the method of computer modeling using the Ansys Fluent hydrodynamic package. To approximate the complex dependence of the carryover into the room, and the concentration in the breathing zone of harmful impurities on the main influencing factors, it is proposed to use a neural network of direct propagation. The architecture and results of testing a neural network model of one of the types of exhaust devices are presented.

COMBINED METHOD OF INTEGRAL TRANSFORMS FOR THE SPHERICALLY SYMMETRIC DROPLET HEATING PROBLEM

In this paper, we analysed the spherically symmetric heat diffusion equation, which governs the temperature distribution inside a heated but non-evaporating droplet. The spherical droplet, with an initial uniform temperature, is assumed at rest in an unsteady gas environment. The classical Fourier sine integral transform (FSIT) and the unilateral Laplace integral transform (LIT) are successively used to solve the resulting initial-boundary value problem, first reduced in a dimensionless form. An explicit solution in the Laplace domain is obtained for the temperature inside the droplet. Then, depending on the time-varying temperature of the gas environment at the immediate vicinity of the droplet, an exact series solution and an approximate analytical solution in short time limits are derived for the droplet internal temperature. In the case of steady gas environment at constant temperature, the standard series solution obtained in the literature for the symmetrical problem of heating or cooling of a solid spherical body, is recovered. The results may be useful for time step analysis in droplets and sprays vaporization models.