Transactions of the Tambov State Technical University

A new approach to the development of a methodology for the integrated design of cyclic adsorption processes and units for separating multicomponent gas mixtures in the presence of uncertainty in some of the initial design data is proposed. The paper describes a composition of a problem-oriented complex for conducting pre-design scientific research and substantiating the adoption of design solutions for the hardware and technological design of cyclic adsorption processes and units (for separating multicomponent gas mixtures and concentrating gases (oxygen, hydrogen, nitrogen, etc.) widely used in technology and the social sphere). The general formulation of the problem of the dynamics of cyclic sorption processes and methods for solving it, a generalized procedure for constructing a mathematical model of the dynamics of sorption in cyclic adsorption processes of separating gas mixtures are presented. The procedure for preparing the initial data for designing and substantiating design solutions in the hardware and technological design of cyclic processes of adsorption separation of multicomponent gas mixtures is given as part of a problem-oriented hardware and software complex.

The kinetic model of the curing process is an integral part of the modeling and optimization of the technological process for the production of polymer composites articles. The kinetic characteristics of the model are determined empirically based on calorimetric measurements and have a significant impact on the results of calculations of cure cycles. The paper discusses a method for calculating the kinetic characteristics of polymer composites cure. Graphical dependences of heat generation power and kinetic characteristics are shown. Estimates of root-mean-square errors were obtained and an analysis of the sources of errors in kinetic characteristics was carried out. Recommendations have been developed for planning an experiment to determine the kinetic characteristics of the polymer composites curing process with minimal errors.

The article presents the results of a study of the minimum time for measuring the frequency responses (FR) of low-pass filters (LPF) when exposed to a digitally method generated fragment of a signal with a limited equal-amplitude complex spectrum (LEACS). A comparative analysis of the processes for measuring the frequency response of a Chebyshev low-pass filter of the sixth order showed that the time to establish the spectrum of the low-pass filter response to the SRCS is significantly less than the sweep time when using a chirp-signal.

In this paper, the principles of constructing linear automation systems designed to move their parameter under study in circuits with different time constants are considered. Modeling of such systems is based on realizations of electrical circuits that allow one to obtain the required time constants. To do this, on the basis of differential equations that describe the behavior of the circuits under study, characteristic equations are formed. The roots of these equations make it possible to determine the mode of operation of the circuits under study and the time constants. Electrical circuits are selected as the circuits, in which the parameter under study is the voltage on the capacitor.

For typical fibrous cotton materials, the equilibrium in the fibrous material-sodium hydroxide solution system was studied and analyzed. Sorption characteristics are necessary when calculating the process of alkali extraction after mercerization of cotton fibrous materials. The curves of sorption and desorption kinetics for typical light and medium density cotton flat fibrous materials are presented. The results obtained make it possible to determine the equilibrium constants during sorption and desorption of alkali from the studied processing objects.

The results of a study of the kinetics of solid-phase enzymatic hydrolysis of cellulose-containing raw materials in a static-dynamic mode using a culture of the Trichoderma viride microscopic fungus depending on the fractional composition of the substrate are presented. Variants of the process organization with a solid substrate of fine (0–1 mm), moderate (1–3 mm) and coarse (3–5 mm) dispersion are investigated. It was found that the highest concentration of growth factors is achieved in an enzymatic medium prepared using a solid substrate of moderate dispersion. The use of such a substrate provides favorable conditions for intensive volumetric aeration of the enzymatic medium and diffusion contact of the components of the enzyme-substrate complex. The degree of cellulose bioconversion achieved during four days of fermentolysis on a substrate with moderate dispersion is 20 % higher than on finely and coarsely dispersed substrates.

In isolated objects, oxygen sources are usually inorganic superoxides, chlorates and metal perchlorates. Chemical oxygen generators are made from them, mainly in the form of chlorate candles, which release oxygen when burning. The morphology of sodium chlorate samples from different manufacturers and the features of thermal decomposition of sodium chlorate and perchlorate with different particle sizes were studied to develop a technology for the production of a thermochemical oxygen generator.

Samples of modified multilayer carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) were obtained by treatment in vapor and isopropanol solutions of iodine at different ratios of components. The physical and chemical parameters of the modified CNTs and GNPs were determined by X-ray phase analysis and Raman spectroscopy. It was found that liquid-phase processing promotes more efficient iodine incorporation into the materials than gas-phase processing. At exposure of CNTs in iodine vapor, removal of amorphous phase from the material and production of surface defects due to the formation of bonds with iodine are observed. When treated in isopropanol solutions of I₂, changes in the surface structure of nanotubes are less significant. Thermal treatment of liquid-phase iodinated CNTs at 620 °С contributes to the removal of most of the iodine, but 0.2–0.3 wt. % of the doping element is retained in the material composition.