A model predictive controller of the blowing mode during basic oxygen furnance process

Today in Ukraine and the world, the problem of energy saving and reducing the cost of smelted steel is state of art. Metallurgical enterprises are developing in conditions of fierce competition, the main reason is that Ukrainian products are extremely energy-intensive due to the depreciation of fixed assets and outdated technological processes. The basic oxygen furnace process is a process of producing steel from liquid cast iron with the addition of steel scrap to the converter and blowing oxygen from above through a water-cooling lance. Nowadays, the production of steel by BOF process is the most popular in the world and is becoming increasingly common. The main disadvantage of the basic oxygen furnace is the need to provide the initial amount of heat (in the form of liquid cast iron) and as a consequence - restrictions on the processing of scrap metal. Reducing the cost of basic oxygen furnace steel is achieved by increasing the share of scrap metal by increasing the degree of afterburning of CO to CO2 in the cavity of the converter, by optimal control of the parameters of the blast mode using model-predictive control. The principle of model-predictive control is based on a mathematical model of the plant. This approach minimizes the functional that characterizes the quality of the process. The linear-quadratic functional was chosen. A forecasting model is proposed taking into account the constraint on changing the position of the lance and the pneumatic oxygen supply valve. It was found that the change in the rate of decarburization of the metal depends on the distance of the lance to the level of the quiet bath and affects the degree of afterburning of CO to CO2. The decarburization process is non-stationary, described by a first-order inertial model, the transfer coefficient and time constant of which depends on the melting period and the duration of the purge. The mathematical model of the blast mode of oxygen-converter melting has been improved, taking into account the influence of the blast intensity on the decarburization process of the bath, which allowed to increase the accuracy and quality of blast control in terms of changing oxygen flow during purging. The simulation results of the automatic control system show that the model-predictive regulator provides the required level of carbon dioxide in the converter gases when the flow rate of oxygen for purge changes.

Analysis of the frequency characteristics of the control system for the processes of fuel supply to the cylinders of the power unit

The idea of monitoring the identity of the cylinder capacities of an internal combustion engine under conditions of incomplete information is proposed and a computer system is built on its basis. The signal of the instantaneous rotation speed of the crankshaft of the power unit was used as input information. In the development of the hardware architecture, injectors with piezoelectric actuators, the principle of direct digital control, and the principle of control with feedback on the state of fluctuations of the crankshaft rotation speed were used. The Laplace transform was used as a mathematical apparatus for analyzing the structural diagram of a computer system for programmed control of the processes of supplying fuel and air to the cylinders of the power unit. Mathematical models of the components of the hardware for controlling the processes of supplying the fuel-air mixture were constructed, and as a result of the analysis of the structural diagram of the computer system, the transfer function was obtained. Using the capabilities of the Matlab software environment, the transient and impulse transient characteristics of the system are obtained, the Nyquist hodograph is constructed, and the logarithmic amplitude-frequency characteristics of the hardware are established. It was found that the frequency characteristics of the mathematical model of a computer system have the necessary dynamic characteristics. Using the method of expansion into simple fractions, an expression is obtained for a discrete transfer function, the coefficients of the power polynomials of which are established using the method of determinants and computational capabilities of the Mathcad software environment. On the basis of a discrete transfer function, a scheme for computer modeling of the process of processing the signal of the instantaneous speed of rotation of the crankshaft by hardware is constructed. The output signal was obtained by computer simulation, as a result of the analysis of which the speed of the hardware for processing the input information was established.

Weight loss and commodity evaluation of pear fruits during storage depending on the packaging method

Pear fruits have a high biological and nutritional value; however, they are perishable products, storage of which is accompanied by certain difficulties. You can preserve the quality of fresh pears through the use of various packaging methods, among which the use of polyethylene liners is effective. The article presents the results of studies of weight loss and yield of pears during storage, depending on the variety and method of packaging. Conferencia, Noiabrska, and Osnovianska pears of the highest and first commodity varieties were pre-cooled and packed in wooden boxes №3, with a capacity of up to 25 kg (“control” option) and in boxes with a plastic bag liner inserted inside the package 45–50 μm followed by sealing (option “box with a polyethylene liner”). Pear fruits were stored for four months at a temperature of 0 ... + 3 ± 1 ºС and relative humidity of 92% ± 2%. Fruit weight losses were determined by the method of weighing fixed samples, the yield of marketable products - according to DSTU 8326:2015. It was found that during the storage period of pear fruits, their weight loss was 2.3–5%, depending on the variety and method of packaging. In terms of pomological varieties, according to average data, the highest weight loss was pears of the Osnovianska variety – 2.6%. The use of polyethylene liners during the storage of pears helped to reduce losses by 0.5–2.3% depending on the variety and duration of storage. It was found that in the conditions of free air access the share of standard products was 78.6–88.3% with the minimum value in the fruits of Conference and the maximum in the fruits of Noiabrska Moldova. It is proved that packing pear fruits in wooden boxes with polyethylene inserts caused an increase in the yield of marketable products to 90.2–98.4%, a decrease in the share of non-standard products to 1.6–7.0%, and waste to 2.8%. The weight loss of pear fruits of the Noiabrska Moldova variety was 0.3–1.5 lower compared to similar indicators of other varieties. The fruits of the same variety recorded a higher yield of marketable products – 88.3–98.4% depending on the method of storage.

The usage of niche seeds flour in cupcake production technology

Flour confectionery products occupy an important place in the diet of the population of our country, and the world and are in great demand. A significant disadvantage of this group of products is the low content of vital essential substances, such as vitamins, minerals, dietary fiber, etc., and the high content of carbohydrates and lipids. Demand for these products necessitates the need to adjust the chemical composition of these foods. One of the most famous representatives of flour confectionery is cupcakes. In the recipes of cupcakes, the largest share occupies such types of refined raw materials like wheat flour, granulated sugar, fats, which cause an imbalance in their chemical composition, low nutritional value, and high caloric content. As biologically active additives of plant origin, flour from the seeds of various niche crops (flax, hemp, sesame, amaranth, etc.) can be added to the cupcake recipe. After all, this type of raw material is valuable for its composition (the content of proteins, fats, essential amino acids, and fatty acids, vitamins, minerals, etc.) and health properties. The recipe for cupcakes enriched with flour from the seeds of niche crops has been developed. The prototype for the study was chosen recipe for the cake “Stolychnyi”. Hemp, flax, pumpkin, and sesame flour were chosen as raw materials. Organoleptic, physicochemical quality indicators, nutritional, and energy value of finished products are determined. Based on the results of the organoleptic evaluation of cupcake samples, determination of their physicochemical quality indicators, comparison with the production sample, we recommended the introduction of a cupcake enriched with low-fat hemp flour. The protein content in this sample was 8.85 g/100 g, fat – 17.83 g/100 g, carbohydrates – 51.8 g/100 g, energy value – 396.85 kCal / 100 g of product. Due to the functional properties of hemp flour, the resulting product can be attributed to health products.

Properties of interval type-2 fuzzy sets in decision support systems

Definitions and methods of designing interval type-2 fuzzy sets in fuzzy inference systems for control problems of complex technical objects in conditions of uncertainty are considered. The main types of uncertainties, that arise when designing fuzzy inference systems and depend on the number of expert assessments, are described. Methods for assessing intra-uncertainty and inter-uncertainty are proposed, taking into account the different number of expert assessments at the stage of determining the types and number of membership functions. Factors influencing the parameters and properties of interval type-2 fuzzy during experimental studies are determined. Such factors include the number of experiments performed, external factors, technical parameters of the control object, and the reliability of the components of the computer system decision support system. The properties of the lower and upper membership functions of interval type-2 fuzzy sets are investigated on the example of the Gaussian membership function, which is one of the most used in the problems of fuzzy inference systems design. The main features and differences in the methods of determining the lower and upper membership functions of interval type-2 fuzzy sets for different types of uncertainties are taken into account. Methods for determining the footprint of uncertainty, as well as the dependence of its size on the number of expert assessments, are considered. The footprint of uncertainty is characterized by the lower and upper membership functions, and its size directly affects the accuracy of the obtained solutions. Methods for determining interval type-2 fuzzy sets using regulation factors of membership function parameters for intra-uncertainty and weighting factors of membership functions for inter-uncertainties have been developed. The regulation factor of the function parameters can be used to describe the lower and upper membership functions while determining the size of the footprint of uncertainty. Complex interval type-2 sets are determined to take into account inter-uncertainties in the problems of fuzzy inference systems design.

Improving the productivity of Pini-Kay fuel briquettes by modernizing the working part of the PSH-250 press

The research related to the productivity of production of fuel briquettes of the "Pini-Kay" type, due to the modernization of the working part of the press line for the production of fuel briquettes with a capacity of 250 kg / h (LVB - 250) was carried out. It is known that the press used on this line is PSH-250, it is the main working equipment of this line, as it serves to press the briquette under temperature and is the closing link in the whole briquette process. In the presented study, the main criterion of productivity was considered to be the number of manufactured products before the break of the splined auger, because the breakdown forces to stop the equipment and replace it. This in turn reduces the number of manufactured products. The paper states that the modernization was carried out as follows: the slot screw, which is the main working body of the press PSH - 250, made of structural steel (steel 45) by casting, was replaced by a slotted screw made by machining on CNC machines, high-quality structural alloy steel 40HMFA. This steel is used to make splined shafts, connecting rods and rods, and is best suited for making a splined auger. In addition, to increase the structural strength, the workpiece of the auger, was made heat treatment - normalization. The proposed technological solution allowed to increase the productivity of fuel briquettes, by reducing the downtime of equipment for repair and replacement of working parts of the press PSH-250. This in turn reduced the company's financial costs for spare parts and affected the cost of finished products. The obtained results show that the slotted augers proposed by the authors allowed to increase the productivity of fuel briquettes production almost 10 times in comparison with the previous results.

The viscoelastic properties of a halogen-free polymer composition, for cable products

The viscoelastic properties of a halogen-free polymer composition for cable products have been investigated. The influence of temperature parameters, shear rate on the die-swell ratio of the polymer composition has been determined; the dependence of the melt density on a temperature was investigated. The polymer matrix is a mixture of polyolefins (linear low density polyethylene; polyolefin elastomer and maleic anhydride modified linear low density polyethylene) as a flame retardant filler for the polymer composition is trihydrate alumina. The content of flame retardant filler in the polymer composition is 60 %. The polymer composition was manufactured on the compounding line of X-Compound, Switzerland. The investigation of both melt density and die-swell ratio of the polymer composition has been conducted with help of capillary viscometer type IIRT-AM. To determine the density of the melt the ratio of capillary length to diameter L/D=8/2 was used. The results of the study of the dependence of the melt density of the polymer matrix from a temperature of 150–190 °C at different loads showed that this parameter decreases from 789 to 744 kg/m3 and for polymer composition from 1309 to 1268 kg/m3. The die-swell ratio in the case of an increase of the shear rate at temperatures of 150–190°C for the polymer matrix increases from 1,102 to 1,520, and for the polymer composition decreases from 1,056 to 1,018. The investigation results of the dependence of both die-swell ratio of the polymer matrix and the polymer composition on the ratio of the length of the forming tool to the diameter indicates that the die-swell ratio for the polymer matrix was reduced from 1,296 to 1,152, and for the polymer composition from 1,045 to 1,01. It was established that the viscoelastic properties of the halogen-free polymer composition are significantly influenced by: processing temperature, shear rate, melt density, the ratio of the length of the forming tool to the diameter. The research results give a possibility for a reasonable approach for the determination of technological parameters of an insulation, sheathing of power cables and optical cables of microtube construction. It will also allow to quickly adjust the geometrical parameters of the forming tool of cable heads.

Improving of the vector control system structure of the active controlled rectifier

The vast majority of electricity is used by industrial facilities in a converted form. At the same time, the use of semiconductor converters to obtain the required load parameters is intensively increasing. Current trends in the development and improvement of semiconductor converters are aimed at energy saving by improving their quality of work and reducing the impact on the power supply, load, and related consumers. Frequency converter with DC insert has become widespread and widely used. Its scheme is mainly based on an uncontrolled diode rectifier and an autonomous voltage inverter. Uncontrolled rectifiers are simple and reliable, but have two main disadvantages: the impossibility to recover electricity to the supply network and distortions of the source current shape. We can get rid of these disadvantages by using an active rectifier made according to the voltage source scheme instead of an uncontrolled rectifier. The operation of an active rectifier significantly depends on the type of its control system structure. This article aims to to improve the structure of the switches control system of the active rectifier scheme – voltage source built using a vector calculation algorithm; creation of a MatLab model of a three-phase active-controlled rectifier operating with a fixed modulation frequency and analysis of the influence of the input inductance value on the quality of its operation. The simulation results confirm that the improved structure of the vector control system proposed by the authors ensures high-quality operation of the active rectifier and electromagnetic compatibility of the frequency converter with the power supply network at the level allowed by the standards; simplification of the representation mathematical apparatus of the generalized vectors of currents and voltages at the construction of a vector control system of the active rectifier – voltage source practically did not influence qualitative indicators of the converter work in any way; a network filter must be used to eliminate the final distortions introduced into the source voltage by an additional nonlinear load.

Application and schemes of induction preliminary heating in magnetic-pulse treatment of metals

The features of the processes of magnetic-pulse processing of metals in traditional schemes of technological processes of modern industrial production are highlighted. The work is a brief description of the state, application, and also proposed induction pre-heating schemes in industrial magnetic-pulse processing of metals. A method for increasing the efficiency of performing specified production operations is considered. The use of preheating leads to a significant improvement in the quality of production operations while reducing energy consumption. New directions of magnetic-pulse processing of metals are noted, implying the transformation of the natural repulsive forces of the metal of the processed object into the forces of magnetic-pulse attraction with a decrease in the operating frequencies of the acting fields. A significant decrease in operating frequencies makes it possible not only to go from repulsion to attraction, but also to go from working with ferromagnetic metals to non-ferromagnetic ones. For example, it becomes possible to attract aluminum blanks. Examples of the use of induction heating of metal blanks in modern industry are given. Various devices used for these operations, offered on the modern market, by both domestic and foreign manufacturers, are considered. The physics of Lenz-Joule heat release is described, the result of which is the induction heating of conductors by Foucault currents in the external electromagnetic field of the instrument. Schemes are proposed for the practical implementation of preliminary induction heating during magnetic-pulse processing of metal blanks, allowing the use of both autonomous devices for exciting eddy currents and a stationary connection, for the same purpose, of an additional source of electricity. As a result of the work, the possibility of increasing the efficiency by increasing the plasticity of the metal when heating the workpiece, as well as possible limitations of the described technology associated with an increase in the active resistance of metals with an increase in the Lenz-Joule heat release is noted.

Sustainable eating behavior

With the growing impact of agriculture and modern food processing on the natural environment and growing concerns about all aspects of their sustainability, urgent solutions are required to promote healthy, low-impact diets. Sustainable diets are those with low environmental impact and high availability that ensure food and nutritional security. A comprehensive overview of different approaches to the analysis of sustainable eating behavior is provided. It is argued that preserving the environment is critical, including in designing programs to improve health, address inequalities in affordability, food access and availability in food system models. However, dietary advice and food policy should not be based solely on the environmental aspect of sustainability and should be carefully formulated. Economy, culture and other sociological factors should be taken into account in appropriate policies when planning ways to provide adequate nutrition to the population. It is emphasized that building sustainable food systems that support healthy communities requires a multidimensional, interdisciplinary approach. A sustainable healthy diet is based on improving the energy balance and changing the diet towards a predominantly plant-based diet, which is in line with the data on healthy eating. Updating national guidelines to reflect the latest data on healthy diets may in itself be important for improving health and reducing environmental impact, and may not only clearly define but expand the criteria for sustainability. Key principles of environmental sustainability and well-being are applied in shaping a national sustainable food strategy and are directly related to food production and consumption. To implement an integrated health and environment modeling framework, it is necessary to take different approaches to sustainable nutrition, motivating environmental, food security and public health goals. To develop a methodology for assessing indicators of sustainable nutrition, it is important to simultaneously take into account all aspects: nutritional value of products, indicators of environmental impact, availability of products, climatic, geographic and national characteristics. This methodology will allow to make competent decisions in the field of food production and consumption, will help to minimize the negative impact on the natural environment through sustainable eating behavior.