Automated air pressure control system in a motorised breathing apparatus

The relevance of the study is to develop an effective system for controlling the pressure in the air supply in motorised breathing apparatus to ensure effective protection of employees from dangerous aerosols and improve their health. The goal was to create an automated air pressure control system in a motorised breathing apparatus using a proportional-integral-derivative controller. For this purpose, the simulation method was used. In order to avoid unforeseen situations of deterioration of the level of protection, the structure of the pressure control system of a motorised respirator has been developed with the selection of the appropriate controller based on the obtained dependences of the influence of the parameters of the breathing mode and the amount of pressure in the under-mask space of the respirator, which ensures an appropriate comfortable mode of operation. This allowed developing a simulation model with a PID controller that would provide the appropriate pressure values within the permissible limits (50-370 Pa). It is proved that the proportional-integral-derivative controller maintains the pressure in the respirator mask within certain limits both with an increase and with a decrease in the control signal, preventing excessive fluctuations in the controlling variable, which leads to an extension of the service life of the filter elements and a reduction in electricity consumption for the operation of the fan motor. Based on modelling the operation of the pressure control system in different modes of operation, it is shown that when using a PID controller with defined parameters, the system provides compensation for changes in air pressure in the under-mask space of the respirator in different breathing modes of the user. The results can find practical applications in the field of safety and health, in industrial environments where workers are at risk of inhaling dangerous aerosols, such as toxic particles, gases, or other harmful substance

Probabilistic estimation of risk of acute professional disease (poisoning) of workers of agriculture at handling poisonous chemicals

Проведена вероятностная оценка риска острого профессионального заболевания (отравления) работников сельского хозяйства, использующих в технологическом процессе различные ядовитые химические вещества. Определены наиболее значимые производственные факторы, влияющие на возникновение опасной ситуации, связанной с возможностью отравления работников, применяющих данные вещества.The probabilistic estimation of risk of the sharp professional disease (poisoning) of workers of agriculture, using different poisonous chemicals in a technological process, is conducted. The most meaningful productive factors, influencing on the origin of the nearaccident, related to possibility of poisoning of workers applying these substances, are certain

Зв’язок функціональної активності клітин-попередників кісткового мозку при хронічній мієлоїдній лейкемії з індивідуальною відповіддю на терапію

Показано ефективність застосування культуральних методів дослідження клітин-поперед­ників кісткового мозку для моніторингу індивідуальної відповіді пацієнтів із хронічною мієлоїдною лейкемією на терапію інгібіторами тирозинкіназ (ТКі). Аналіз особливостей росту гемопоетичних клітин при хронічній мієлоїдній лейкемії показав, що функціональна активність кровотвірних клітин-попередників у осіб, які демонструють повну відповідь на терапію ТКі, була достовірно нижчою (р < 0,05) ефективності колонієутворення для зразків кісткового мозку осіб із відсутністю відповіді на терапію. Виявлено кореляцію між показниками колонієутворення та відсотком клітин із філадель­фійською хромосомою у кістковому мозку, що була позитивною для групи осіб, які отримували альтер­нативне лікування гідроксисечовиною, та негативною для групи осіб із резистентністю до терапії ТКі

Establishing Regularities in the Insulating Capacity of A Foaming Agent for Localizing Flammable Liquids

Designing environmentally friendly protective materials for flammable liquids makes it possible to influence the processes of heat resistance and the physical-chemical properties of a protective coating over a certain time until the emergency is eliminated. Therefore, there is a need to study the conditions that form a barrier for thermal conductivity and to define a mechanism for decelerating the transfer of heat to a flammable liquid by using a foaming agent. Given this, a mathematical model has been built for the process of changing the concentration of a foaming agent when used as a coating. Based on the experimental data, it was established that the foaming layer destruction process took place over 618 s until the achieved critical thickness of the foaming layer made the conductivity cease. According to the derived dependences, the concentration value was calculated at which the critical value of the foaming layer thickness is achieved, which leads to the ignition of a flammable liquid, and is about 25 %. It has been proven that the process of decelerating the temperature involves the decomposition of a foaming agent under the influence of the temperature, with heat absorption and foam release, the insulation of heat at the surface of the flammable liquid. Given this, it has become possible to define the conditions for protecting flammable liquids using foaming agents by forming a barrier to thermal conductivity. Experimental studies have confirmed that under the influence of water evaporation and foaming agent diffusion into a layer of the flammable liquid, the critical amount of the foaming agent reached a minimum in 606 s and only then the flammable liquid ignited. Thus, there is reason to argue about the possibility of using foaming agents to protect the leaks of flammable liquids, capable of forming a protective layer at the surface of the material. It also becomes possible to establish methods for assessing the insulating capacity of a foaming agent that could inhibit the rate of temperature penetration and the release of flammable liquids' vapor

Defining the Features of Structural and Phase Transformations in the Recycling of Anthropogenic Metallurgical Waste Containing Refractory Elements

This paper reports a study into the features of the phase composition and microstructure of a master alloy obtained by using the reduction melting of oxide man-made waste. That was necessary to define those technological indicators that provide for an increase in the degree of extraction of alloying elements during the recycling of anthropogenic raw materials and the subsequent use of the alloying material. It has been determined that the phase composition of the alloy at a Si:C ratio in the charge of 0.11 mainly consisted of a solid solution of elements in α-Fe, as well as carbides Fe3C and Fe3W3C. At the Si:C ratios in the charge of 0.28 and 0.52, along with a solid solution of the elements in α-Fe, Fe8Si2C, Fe5Si3, and FeSiC, FeSi2 manifested themselves, respectively. The microstructure of the alloy demonstrated a clear manifestation of several phases with different content of alloying elements. Changing a Si:C ratio in the charge from 0.11 to 0.28 and 0.52 led to an increase in the residual silicon content (wt %) in the studied areas, from 0.00–0.25 to 0.12–1.79 and 0.20–2.11, respectively. At the same time, the carbon content (wt %) in the examined areas varied from 0.25–2.12 to 0.24–2.52 and 0.45–2.68, respectively. The content of alloying elements in the investigated areas varied within (wt %): W – 0.00–43.06, Mo – 0.00–32.72, V – 0.19–20.72, Cr – 0.69–33.94, Co – 0.00–3.96. Analysis of the study's results reveals that the most acceptable ratio of Si:C in the charge is 0.52. In this case, there is a certain content of residual silicon along with carbon in the form of carbosilicide and silicide compounds. Such indicators of the alloy provide sufficient reducing capacity of the alloy when used. The properties of the alloy make it possible, when smelting steels, to replace part of those standard ferroalloys that do not have strict carbon restrictions

Production of slow extracted beams for CERN's East Area at the Proton Synchrotron

Since the upgrade and renovation of the East Experimental Area at CERN during Long Shutdown 2 (LS2: 2019 - 2021), demand has increased for slowly extracted beam from the CERN Proton Synchrotron (PS). The East Area is a multi-user facility carrying out a diverse experimental physics programme. It requires a wide range of slowly extracted beams to be delivered by the PS. This contribution summarises the gained understanding, progress and improvements made since LS2 in the slow extraction of both proton and ion beams. Furthermore, it describes the production of low intensity, variable energy, heavy-ion beams for a collaboration between CERN and the European Space Agency, striving to establish a novel and flexible high-energy heavy-ion radiation test facility

Identification of Patterns in the Structural and Phase Composition of the Doping Alloy Derived From Metallurgical Waste Processing

This paper reports a study into the structural-phase composition of the doping alloy made by processing metallurgical anthropogenic waste involving reduction smelting. This is required for determining the technological parameters that ensure an increase in the level of extraction of target elements during the processing of anthropogenic waste and for the further use of the doping alloy. It was revealed that the phase composition of the doping alloy manifested a solid solution of the doping elements and carbon in α-Fe. Cementite Fe3C and silicides Fe5Si3, FeSi, and FeSi2 were also identified. In this case, the doping elements were more likely to act as substitution atoms. It has been determined that the microstructure of the alloy consisted of several phases of different shapes and contents of the basic doping elements. Sites with an elevated iron level of up to 95.87 % by weight in the composition could be represented by the solid solution phase of the doping elements and carbon in α-Fe. The sites with a relatively high (% by weight) content of carbon (0.83‒2.17) and doping elements ‒ W, up to 39.41; Mo, up to 26.17; V, to 31.42; Cr, to 9.15 ‒ were apparently of a carbide nature. The sites with a silicon content of 0.43‒0.76 % by weight likely included silicide compounds. The alloy's characteristics make it possible to smelt steel grades without strict carbon restrictions, replacing some of the standard ferroalloys. Neither phases nor compounds with a relatively high propensity for sublimation were identified in the material produced. Therefore, there is no need to provide conditions to prevent evaporation and loss in the gas phase of the doping elements. That could increase the degree of extraction of the doping element

Determining the Thermal Mode of Bio-based Raw Materials Composting Process in A Rotary-type Chamber

One of the promising methods to dispose of agricultural bio-based raw materials is to produce compost by aerobic fermentation in rotary chambers. High efficiency of the composting process is achieved when a proper temperature mode is maintained at each phase of the process. Changes in temperature are directly related to the effective transformation of organic substrates by microorganisms and are the reason for the low quality of produced compost in terms of its agrochemical and microbiological parameters. It was established that a high-temperature regime is achieved on the condition that the amount of heat released during the biodegradation of raw materials by microorganisms is greater than the heat loss associated with the substrate aeration and surface cooling. Therefore, the time during which the fermented mass remains warm depends entirely on the substrate's physical-chemical characteristics, the parameters of the equipment, and the modes of its operation. To describe the established conditions, based on the equation of thermal balance, a mathematical model has been built. The model relates the thermal costs necessary to maintain the optimal temperature regime of the process to the substrate's moisture content and specific active heat generation, as well as to such an important thermal physical parameter of the chamber as the coefficient of heat transfer of the wall material. A rotary chamber was manufactured to investigate the thermal mode of the bio-based raw materials composting process. It has been experimentally established that the chamber walls' heat transfer coefficient of 1.6 W/(m2·°C), a value of the substrate's specific active heat generation of 9.2 W/kg, and a moisture content of 58 % provide for the thermal needs for the process with the release of 140 MJ of excess heat. The reported study could be the basis for the modernized methodology of thermal calculations of the bio-based raw materials composting process in closed fermentation chamber