Рассмотрена структура энергетических потерь за счет трения кинематических пар. Определены основные причины выхода из строя аппаратов, имеющих пары трения. Показаны преимущества и недостатки автоматических централизованных систем смазывания, приведена их классификация и области применения. Приведены результаты сравнения ресурсных и временных затрат для машин (карьерные экскаваторы, троллейбусы) с использованием автоматических централизованных смазочных систем и без. Предложены направления по улучшению процесса смазывания и повышению ресурса промышленного оборудования.

Визначено вплив вмісту тканинного інгібітора металопротеїнази-1 (ТІМП-1) на рецидивування фібриляції передсердь (ФП) після процедури катетерної радіочастотної абляції (КРА). ТІМП-1 бере участь у ремоделюванні позаклітинного матриксу, який вважається маркером регуляції активності матриксних металопротеїназ. За допомогою імуноферментного аналізу до процедури КРА вимірювали сироватковий вміст ТІМП-1 у 210 пацієнтів: 80 пацієнтів без анамнезу ФП і 130 з ідіопатичною формою ФП (пароксизмальна-30, персистуюча-32, тривало-персистуюча-35 і хронічна-33). Оцінювали їх зв'язок з інтраопераційною ефективністю і рецидивом ФП протягом усього періоду спостереження, який становив 22,2 +- 7,9 міс. Вміст ТІМП-1 був вище в контрольній групі (103,6 +- 14,7 нг/мл), у пацієнтів з ФП - 131,51 +- 36,40, 149,5 +- 42,7, 151,5 +- 42,7 і 155,9 +- 44,7 нг/мл для пароксизмальної, персистуючої, тривалої і постійної форм відповідно. З прогресування ФП цей показник збільшувався. Багатофакторний аналіз показав, що вміст ТІМП-1, анамнез ФП і об'єм лівого передсердя були незалежними предикторами відновлення синусового ритму і рецидиву після процедури КРА. ТІМП-1 є прогностичним критерієм рецидиву аритмії після КРА.

This paper reports the principles of design and the examined protective properties of liquid materials for shielding the electric, magnetic, and electromagnetic fields over a wide frequency range. The materials were made on the basis of iron ore concentrate and a pigment additive, with water-dispersed and geopolymer paints used as a matrix. The tests of protective properties for the electrical and magnetic components of the electromagnetic field of industrial frequency showed that the electric field shielding coefficients at a concentration of the screening substance of 15 - 60 % (by weight) equaled 1,1 - 8,6; magnetic field - 1,2 - 5,3. The shielding coefficients of the material based on a water-dispersed paint are lower than those of a geopolymer one, which can be explained by the oxidation of an iron-containing component and a decrease in electrical conductivity. The shielding coefficients of the electromagnetic field with a frequency of 2,45 GHz are 1,2 - 7,9. The highest coefficients are inherent in the material with filler made of iron ore concentrate and titanium-containing pigment powder in a ratio of 1:1. To design materials with the required (predictable) protective properties, the relative magnetic, dielectric permeability of materials was calculated. It is shown that the obtained data are acceptably the same as the results from direct measurements of magnetic and dielectric permeability and could be used to calculate the wave resistance of the material and the predicted reflection coefficient of electromagnetic waves. Thus, there is reason to assert the need to build a database on the frequency dependence of effective magnetic and dielectric permeability in order to automate the design processes of composite materials with predefined protective properties.

This paper reports a study into the levels of magnetic fields induced by arc welding equipment in various ways in order to assess their impact on the body of welders. It is known that welders are exposed to a magnetic field of high intensity. Depending on the welding technique and the type of welding equipment, it may exceed the maximum permissible levels (MPL). Note that new Ukrainian sanitary standards for magnetic fields have been introduced, which regulate their levels depending on the frequency range. Therefore, it became necessary to carry out their hygienic assessment according to the new standards in order to devise appropriate methods for protecting welders. To this end, it was required to choose a new generation of devices to determine the intensity of magnetic fields induced by welding equipment. Based on the analysis of the constructed oscillograms and spectrograms of magnetic fields, it was found that semiautomatic welding with a metal electrode in carbon dioxide is characterized by an increased level of magnetic field in the frequency range of 50 - 1000 Hz. With automatic arc welding under the flux, there are no excess of the maximum permissible levels of individual harmonics of the magnetic field but there is an excess of the total value of all harmonic components of the magnetic field. Manual arc welding with direct current involving a non-melting electrode in argon is characterized by a moderate level of magnetic field in workplace. During manual arc welding with coated electrodes, the exceeded level of the magnetic field is observed only on the electrode cable itself. It is shown that the spectral composition of the magnetic field signal is determined mainly by the welding technique itself, the peculiarities of arc combustion, and the nature of the transfer of electrode metal in the arc gap, as well as the initial parameters of the power supplies of the welding arc.

The object of this study is the quantitative characteristics of magnetic fields induced during electric contact welding in various ways: contact point, arc-butt, capacitor point, contact-butt continuous, and pulsating fusion. The problem to be solved is the lack of necessary information regarding the electromagnetic safety of these welding techniques. A description of the proposed methodological approaches to determining the levels of magnetic fields, their measurement tools, and methods for assessing their impact on the welder's body is given. Based on the analysis and processing of the acquired oscillograms and spectrograms of magnetic fields, their quantitative characteristics were measured. To determine the general level of the polyfrequency magnetic field arising at contact welding, the proposed generalized indicator of the level of the magnetic field was used. It was established that during contact point welding by a stationary machine, the level of the magnetic field exceeds the maximum permissible value at the workplace in the range of 50 - 1000 Hz at a distance of 0,3 m from the welding electrodes. When manually welding in this way, the magnetic field level exceeds the permissible level in the frequency bands of 5 - 50, 50 - 1000 Hz directly near the electrical cable. Capacitor spot welding with direct current is characterized by exceeding the maximum permissible MP at the workplace in the high-frequency range of 1000 - 10 000 Hz. During arc-butt welding, no excess of the maximum permissible levels of the magnetic field was detected at the workplace. It is shown that the spectral composition and magnitude of the magnetic field signal is determined by the welding technique and the initial parameters of power supplies. Orimani results can be used in the field of welding production and labor protection.